• Clinical Abstracts

    Clinical Abstracts on Transesophageal Electrophysiology

    A gastroesophageal electrode for electrophysiological studies. McEneaney DJ, Escalona O, Anderson JA, Adgey AA. Regional Medical Cardiology Centre, Royal Victoria Hospital, Belfast. Pacing Clin Electrophysiol 1999 Mar;22(3):487-99. A novel gastroesophageal electrode has been developed capable of atrial and ventricular pacing. We performed electrophysiological studies using the gastroesophageal electrode (Esothoracic) and compared the results with the standard endocardial approach. The flexible polythene gastroesophageal electrode was passed into the stomach under light sedation. Five ring electrodes, now positioned in the lower esophagus were used for bipolar atrial pacing and recording. Ventricular pacing was performed using a cathodic point source on the gastroesophageal electrode tip; the indifferent electrode (anode) was a high impedance chest pad. Parameters of sinus and AV nodal function were obtained by atrial pacing. Programmed ventricular stimulation was performed using a standard protocol. These electrophysiological parameters were subsequently determined using the endocardial approach. There was close correlation between measurements of sinus and AV node function using the two approaches in 48 subjects: sinus node recovery time (SNRT) r2 = 0.70, corrected sinus node recovery time (CSNRT) r2 = 0.87, AV Wenckebach cycle length (AVWCL) r2 = 0.97. The degree of agreement between the two approaches was estimated by the mean difference delta and standard deviation of the difference sigma (SNRT delta = 40 ms, sigma = 257 ms; CSNRT sigma = 14 ms, delta = 164 ms; AVWCL sigma = 7 ms, delta = 16 ms). Programmed ventricular stimulation was performed in 15 of 48 subjects with known or suspected ventricular tachyarrhythmias. Seven had ventricular tachycardia induced using both esothoracic and endocardial programmed ventricular stimulation. One subject was noninducible using esothoracic programmed ventricular stimulation, but inducible at endocardial electrophysiological studies. Another subject was inducible at esothoracic electrophysiological studies, but noninducible using endocardial programmed ventricular stimulation. Six subjects were noninducible using both endocardial and esothoracic programmed ventricular stimulation. The gastroesophageal electrode permits reliable atrial and ventricular pacing without transvenous catheterization or fluoroscopy. Electrophysiological parameters determined using this electrode are similar to those obtained using endocardial stimulation.

    Supraventricular paroxysmal reentry tachycardia. Empirical and guided therapy. Piccolo E, Bonso A, Raviele A, Delise P. Divisione di Cardiologia, Ospedale Umberto I, Mestre-Venezia. Cardiologia 1991 Aug;36(8 Suppl):87-97. The empirical therapy of reentrant supraventricular tachycardias (A-V and junctional tachycardia) is based on a preliminary diagnosis through standard ECG to evaluate, whenever possible, the relationship between P wave and QRS. In order to distinguish atrial tachycardias from other types, we must employ vagal manoeuvres or drugs. Often we use methods of recording and stimulation such as Holter monitoring and transesophageal technique which can provide useful information about the electrophysiological mechanisms and therefore can better guide our choice of drugs. The decision of undertaking pharmacologic treatment takes into account frequency, duration and tolerability of the crises and the patient's compliance. The most commonly used drugs are verapamil, diltiazem, propafenone, flecainide, sotalol and amiodarone. The percentage of success at 1 year ranges from 30 to 60%. Particularly in the Wolff-Parkinson-White (WPW) therapy must follow an accurate evaluation of the electrophysiological pattern through effort test, drugs test, transesophageal (ETS) or endocavitary (EPS) electrophysiological study. Indeed therapy aims not only at reducing arrhythmic relapses, but also preventing the potential risk of either death or severe damage. The useful drugs must have the property of acting at the same time upon at least one branch of the A-V circuit, on the atrium reducing its vulnerability and finally modifying the conductive anterograde capacity of the Kent bundle. They are quinidine, procainamide, propafenone (group I) sotalol and amiodarone (group III). The limitations of the empirical therapy are a high percentage of relapses and the difficulty in foreseeing the pro-arrhythmic effects. The guided by serial electrophysiologic testing implies artificial induction of spontaneous arrhythmia by repeating the test after acute or chronic assumption of drugs. Is this way it can be evaluated the efficacy as well as the tolerability of an antiarrhythmic drug which later will be taken for chronic prophylaxis. The percentage of inducibility of clinical arrhythmias is next to 100% both for EPS and TES. The number of patients for whom we can find an effective pharmacologic regimen through acute testing ranges from 30 to 100%, but is influenced by several factors such as aggressiveness of therapeutic protocol and type and dosage of drugs. The predictive value is high as it approaches 100% for a positive acute test. The elective indications for serial electrophysiologic study are: failure of empirical therapy; disabling and very frequent arrhythmias; arrhythmias provoking major disturbances (lipothymia, syncope, hypotension, shock); symptomatic WPW.

    Comparative study of auricular stimulation by transesophageal and endocavitary approach for evaluating sinus and atrioventricular node function. Cebron JP, Brugada J, Gallay P, Puech P. Arch Mal Coeur Vaiss 1987 Feb;80(2):170-5. The purpose of this study was to find out whether non-invasive transoesophageal pacing could effectively replace right intra-atrial pacing for the indirect evaluation of sinus node and atrioventricular (AV) node function. In a population of 17 patients the corrected sinus node recovery time (CSRT), the atrio-sinu-atrial conduction time (ASACT) and Wenckebach's point (W) were calculated by intracavitary pacing, then by transoesophageal pacing. There was no significant difference between the two methods in pre-pacing sinus cycle. With right intra-atrial pacing, mean CSRT value was 365 +/- 54 ms (with 5 values greater than 520 ms), mean ASACT value was 229 +/- 29 ms (with 8 values greater than 220 ms), and W occurred at a mean cycle length of 425 +/- 29 ms. With transoesophageal pacing, mean CSRT value was 406 +/- 87 ms (with 5 values greater than 520 ms), mean ASACT value was 222 +/- 17 ms (with 8 values greater than 220 ms), and W occurred at a mean cycle length of 408 +/- 26 ms. The two methods correlated very closely for CSRT and W (r = 0.97) and relatively well for ASACT (r = 0.84). The number of CSRT and ASACT values regarded as prolonged was the same with the two methods; 4% of recorded (i.e. maximal) CSRT values occurred with the same length of pacing cycle. There was no statistically significant difference between the two methods in the calculation of CSRT and ASACT, but W occurred at a slightly shorter cycle (p less than 0.05) with transoesophageal pacing. Thus, transoesophageal pacing is a non-invasive, easy to perform method for indirect exploration of sinus node and AV node function in patients who do not require subnodal conduction studies.

    Diagnostic and therapeutic use of transesophageal atrial pacing in children. Janousek J. Center of Pediatric Cardiology and Cardiac Surgery, Prague. Int J Cardiol 1989 Oct;25(1):7-14. Transesophageal atrial pacing was used in 29 consecutive patients aged 1 day to 16.5 years (mean 8.04 years) to replace the following procedures: intracardiac electrophysiologic study in patients with selected arrhythmias (21 patients), intracardiac overdrive or synchronized direct current cardioversion of supraventricular tachyarrhythmias or drug administration in patients with acute reciprocating supraventricular tachycardia (9 patients). Atrial capture was achieved without discomfort in 27 patients (93.1%). The diagnostic or therapeutic goal of the procedure was achieved in 26 children (89.7%). Transesophageal atrial pacing may replace intracardiac pacing procedures, direct current cardioversion and drug administration in patients with selected cardiac arrhythmias and has proved appropriate as a first diagnostic or therapeutic step.

    The study of acute clinical electrophysiological effects of propafenone on paroxysmal supraventricular tachycardia using transesophageal atrial pacing technique. Li Q, Wang Z, Peng D. Department of Cardiology, Second Affiliated Hospital, Hunan Medical University, Changsha. Hunan I Ko Ta Hsueh Hsueh Pao 1997;22(2):123-6. Trans-esophagus atrial pacing (TEAP) was employed to evaluate the acute electrophysiological effects of propafenone administrated intravenously in 50 patients with SVT. Forty three of the subjects are patients with atrial ventricular reciprocating tachycardia (AVRT). Seven of them were involved in atrioventricular nodal reentry tachycardia (AVNRT). The results indicate that propafenone exerts an obvious inhibitory effect on both the dual atrioventricular node pathways and the accessory pathways, with the latter one being markedly affected. In addition, propafenone can deter the antegrade and retrograde conduction and prolong the refractory period of the accessory pathways. Still more, it results in preceding of the Wenchebach and 2 to 1 block point of the atrioventricular node conduction. All these promise the potential terminating effect on tachycardia. Propafenone has little effects on sinus node. Prolongation of sinus node recovery time (SNRT) to 3600 ms following drug administration was observed in only one patient who has a history of sinus bradycardia. 

    The role of an electropharmacological transesophageal test in the prevention of paroxysmal atrial fibrillation. Experience with flecainide. De Sisti A, Matteucci C, Patrissi T, Accogli S, Di Lorenzo M, Sasdelli M, Ciolli A, Lo Sardo G, Palamara A. Divisione di Cardiologia, Ospedale Sandro Pertini, Roma. G Ital Cardiol 1998 Dec;28(12):1391-9. BACKGROUND: The management of patients with paroxysmal atrial fibrillation (AF) is unsuccessful, because AF recurs in about 50% of patients despite an antiarrhythmic treatment. Usefulness of non-pharmacological strategies is available in a limited subset of patients and it does not present a global solution to the problem. At present, treatment with antiarrhythmic agents is the only available tool in patients with AF recurrence. The aim of this study was to assess the predictive value of the electropharmacological transesophageal (TE) test in the management of patients with paroxysmal AF treated by flecainide. METHODS: In 32 patients, ranging in age from 38 to 70 years (mean: 59 +/- 12 years), with documented episodes of paroxysmal AF (mean: 5.6 +/- 3.7 episodes/last year), we performed an electrophysiological transesophageal (TE) test following pharmacological wash-out. An aggressive protocol was used: step A: 10 sec atrial burst at Wenckebach point + 10 bpm, 200 and 250 bpm; step B: 10 sec atrial bursts at 300, 400, 500 and 600 bpm; step C: 8 sec increasing rate burst from 200 to 800 bpm. Induction of sustained AF (> 1 min) was considered the end-point. Patients were treated with flecainide 100 mg bid and a second TE test was performed at the steady-state, with an identical induction protocol and end-point. Based on the response of the second test, patients were divided into responders (R Group: non-inducible AF) and non-responders (NR Group: inducible, sustained AF). Patients were followed-up by periodical controls and contacted by telephone to confirm their clinical status. RESULTS: Sustained AF was induced in 30 patients (94%) at the first TE study. Eight of them dropped-out at the time of the second TE test (6 patients for lack of consent, 1 patient for side-effects and another one for proarrhythmic effects). In the mean follow-up of 15 +/- 6 months, among patients who underwent a second TE test, AF recurrence was documented in 2 out of 14 patients from the R Group and in 7 out of 10 patients from the NR Group (p < 0.01). There were 4 AF episodes in the R Group and 19 in the NR Group (p < 0.001). We did not find significant statistical differences between the two groups in terms of age, sex, body weight, AF episodes/past year, P-wave duration, left atrial dimension, structural heart disease, AF duration at the first TE test and follow-up duration. In five patients from the NR Group with induced AF lasting > 5 min, the percentage of recurrence was 100% and there were 16 AF episodes. Global percentage of patients with recurrence was 37%. CONCLUSIONS: Flecainide is effective in reducing the incidence of AF and results are similar to other antiarrhythmic agents generally used. The electropharmacological TE test might be a useful tool to predict the response to an antiarrhythmic treatment. 

    Study of sinus function and nodal conduction using transesophageal recordings. Le Heuzey JY, Khaznadar G, Guize L, Carcone P, Weissenburger J, Lavergne T, Ourbak P, Valty J. Arch Mal Coeur Vaiss 1987 Jan;80(1):28-35. Transoesophageal pacing is mainly used for treatment of supraventricular tachycardias and assessment of refractory periods of accessory pathways. It has been proposed for the study of sinus node function and A-V nodal conduction. The aim of this study was to know if transoesophageal pacing could modify the vago-sympathetic tone, therefore the results of the tests, knowing it can be discomfortable and that endodigestive procedures can induce vagal responses. Furthermore, the stimulation is elicited near the left atrium, and not in the right atrium as during endocavitary tests. We have compared in 20 patients (age 68 +/- 12) the results obtained by both endocavitary and transoesophageal pacing (tension 21.2 +/- 4.5 V, duration 16 msec, interelectrode spacing 30 mm). We measured sino-atrial conduction time (SACT), sinus node recovery time (SNRT), Wenckebach's point and nodal refractory periods. After introduction of the oesophageal lead we observed a significant (p < 0.01) but slight and transitory tachycardia. The results of A-V nodal conduction parameters were not significantly different and were significantly correlated (r = 0.94 for Wenckebach's point and effective refractory period). For the sinus node function, there was no significant difference between the parameters if the oesophago-atrial delay (mean 104.4 +/- 25.9 msec) is taken into account. The correlation is poor for sino-atrial conduction time (corrected SACT, r = 0.55), tighter for sinus node recovery time (maximal corrected SNRT, r = 0.92).

    Transesophageal stimulation in the treatment of atrial flutter and tachysystole. Factor influencing immediate results.Girardot C, Diebold H, Morelon P, Dentan G, Fraison M, Eicher JC, Bouhey J, Louis P. Hopital du Bocage, Dijon. Arch Mal Coeur Vaiss 1988 Nov;81(11):1379-84. The effectiveness and safety of transoesophageal atrial pacing in the treatment of atrial flutter and tachycardia have been well demonstrated. The purpose of this study was to determine the factors that could influence the results of this method at the end of the procedure. Seventy-seven transoesophageal atrial pacings were performed in 62 unselected consecutive patients with either flutter or atrial tachycardia. The following parameters could be evaluated in 55 patients: date of onset of the arrhythmia, echocardiographic diameter of the left atrium, maximum amplitude of oesophageal atrial potentials, voltage and frequency of stimuli in the last stage of pacing. Our results can be summarized as follows: In both flutter and atrial tachycardia taken globally, conversion to sinus rhythm was obtained in 37% of the cases, and conversion to atrial fibrillation in 46.7% of the cases. The failure rate was 19.4%; all failures were due to lack of atrial capture during pacing. The main factor or transoesophageal atrial capture is voltage. Patients must be able to tolerate the voltage needed for capture. In the case of flutter, when capture was achieved a normal-sized left atrium and a high maximum amplitude of oesophageal atrial potentials were factors indicating that conversion to sinus rhythm could be expected. This, however, did not apply to atrial tachycardia. -- Whatever the type of tachyarrhythmia, the more recent its onset the easier its reduction.

    Diagnostic transesophageal atrial stimulation as a sinus node function test. I. Normal values and comparison with right atrial stimulation. Volkmann H, Paliege R. Z Gesamte Inn Med 1981 May 1;36(9):287-94. For the non-invasive functional analysis of the sinus node diagnostic transoesophageal atrial stimulations were performed. By means of transoesophageal premature individual stimulation we succeeded in a calculation of the so-called sinuatrial conduction time in 112 of 118 normal persons (ESACT = 103 +/- 23.5 ms). In comparison to the results in right-atrial stimulation the transoesophageally established times were 20 to 30 ms longer. By means of transoesophageal atrial stimulation with higher frequency in 64 healthy test persons the recreation time of the sinus node was determined in 64 healthy test persons (ESNRT = 968 +/- 218 ms). Taking into consideration the double standard deviation in an upper limit of 1,400 ms was the result which corresponds to the limit in intraatrial stimulation. In the direct comparison of the transoesophageal and right-atrial stimulation technique in patients with and without syndrome of the sinus node for the sinuatrial conduction time (r = 0.81, n = 51) as well as for the recreation time of the sinus node (r = 0.90, n = 36) relatively good correspondences were found. In the transoesophageal stimulation, however, the larger distance of the place of stimulation from the marginal area of the sinus node, the conduction of the impulse over the left to the right atrium as well as a possible vagal irritation are to be taken into consideration.

    Diagnostic transesophageal atrial stimulation for sinus node function testing. II. Results in patients with and without sinus node syndrome. Volkmann H, Paliege R. Z Gesamte Inn Med 1981 Feb 15;36(4):93-102. By means of transoesophageal atrial stimulation of higher frequency in patients with sinus node syndromes (n = 78) in about 60% of the cases a prolonged sinus node recovery time could be proved. After the end of the stimulation secondary stops appeared in about half of the patients, so that in 81% of the cases at least one pathological result was established. By means of premature individual transoesophageal stimulation (n = 99) in 2/3 of the patients with sinus node syndrome we contrived to perform a calculation of the sinuatrial conduction time. Half of all calculable values were above the normal. In 1/3 of the examined persons pathological stimulation patterns were found. Altogether 90% of the patients showed at least one pathological result, when apart from prolonged sinus node recovery times and sinuatrial conduction times at the same time secondary stops after serial stimulation with higher frequency and abnormal behaviour patterns of the post-extrasystolic stops after individual stimulation were taken into consideration. In patients with different cardiovascular diseases without clinical or electrocardiographic reference to a sinus node dysfunction in 25% of the cases at least one pathological result was found, in which case cannot be clarified, whether latent functional sinus node disturbances or falsely positive results are in question or not. Altogether the non-invasive transoesophageal stimulation technique leads to on principle diagnostic evidences of the same value as the up to now usual stimulation of the right atrium. Methodical problems which arise from the stimulation of the right atrium in transoesophageal approach are to be taken into consideration in the interpretation of the results.

    Esophageal approach in rythmology. Diagnostic and therapeutic applications. Moustaghfir A, van de Walle JP, Deharo JC, Djiane P, Touze JE. Service de Pathologie Cardio-vasculaire, HIA Laveran, Marseille Armees. Ann Cardiol Angeiol (Paris) 1996 Nov;45(9):539-44. The oesophageal route is a simple technique, which is easy to perform. It allows precise assessment of supraventricular arrhythmias without using the endocavitary route. There is a perfect correlation between the two methods for the study of sinus function and the Wenckebach point. This technique makes a considerable contribution to the diagnosis of junctional tachycardia and the evaluation of Wolff-Parkinson-White syndrome. It can reduce approximately 65% of flutters and 50% of atrial tachyarrythmias. It can also be used to monitor antiarrhythmic treatment or in the assessment of radiofrequency resection, especially in nodal tachycardias and left atrioventricular accessory pathways. Its limitations concern the sometimes painful nature of the investigation and the impossibility of recording the electrical activity of the His bundle.

    Programmed atrial stimulation via the esophagus for management of supraventricular arrhythmias in infants and children. Rhodes LA, Walsh EP, Saul JP. Children's Hospital, Harvard Medical School. Am J Cardiol 1994 Aug 15;74(4):353-6.  This report describes the use of programmed atrial stimulation via the esophagus to predict the clinical efficacy of various management strategies for supraventricular arrhythmias in infants and children. A total of 203 transesophageal electrophysiologic studies were performed in 132 patients. Therapies evaluated included medications from each antiarrhythmic class, the Valsalva maneuver, follow-up of radiofrequency ablation, and no therapy. The transesophageal technique appeared to be adequate for inducing tachycardia, yielding a low false-negative rate. Overall, the predictive value of a negative study was high (89%), and increased to 96% when stimulation was performed in the presence of isoproterenol. However, the positive predictive value was significantly lower both with (72%, p < 0.00001) and without (60%, p < 0.0001) isoproterenol. These results were due in part to a very low positive predictive value when evaluating either digoxin and/or beta-blocker therapy, 62% vs 82% for the remaining studies. When clinical tachycardia cannot be induced with therapy, transesophageal techniques can be used to predict freedom from many supraventricular tachycardias for most therapies in children. However, induction of tachycardia may not predict treatment failure. Transesophageal pacing to evaluate arrhythmia therapy may be most useful when managing either severe symptoms, multiple recurrences, or the results of radiofrequency ablation.

    The diagnosis and management of supraventricular tachycardia by transesophageal cardiac stimulation and recording. Harte MT, Teo KK, Horgan JH. Saint Laurence's Hospital, Dublin, Ireland. Chest 1988; 93(2):339-44. Twenty-two consecutive patients underwent esophageal stimulation and recording for the diagnosis and management of supraventricular tachycardia. In 13 of these patients, the resting electrocardiogram was normal and in nine it showed pre-excitation. Of the 13 patients with a normal resting electrocardiogram, supraventricular tachycardia was initiated in all. Seven patients had a ventricular-to-atrial interval greater than 70 ms during supraventricular tachycardia suggesting the presence of a concealed accessory pathway, and six patients had a ventricular-to-atrial interval less than 70 ms during supraventricular tachycardia suggesting reentry within the atrioventricular node. Supraventricular tachycardia was initiated in four of nine patients with pre-excitation on the resting electrocardiogram and the accessory pathway was confirmed by a ventricular-to-atrial interval of greater than 70 ms during supraventricular tachycardia in these four patients. Atrial fibrillation was initiated in eight of the nine patients with pre-excitation on the resting electrocardiogram and the shortest R-R interval during atrial fibrillation was measured. The response to therapy was assessed in seven of these nine patients by further measurement of the shortest R-R interval during atrial fibrillation following treatment. Esophageal stimulation and recording provides a simple noninvasive procedure which can be utilized as a screening technique to identify patients with intranodal reentry and those with reentry utilizing an accessory pathway. Sequential assessment of the response to therapy, especially in those patients with pre-excitation, is of considerable value in treatment.

    Role of transesophageal pacing in evaluation of palpitations in children and adolescents. Pongiglione G, Saul JP, Dunnigan A, Strasburger JF, Benson DW Jr. Children's Memorial Hospital, Chicago. Am J Cardiol 1988 Sep 15;62(9):566-70. Transesophageal atrial pacing was used to evaluate the cause of palpitations in 28 patients ages 3 to 18 years (mean 11). Palpitations were defined as the sustained (seconds to minutes) sensation of rapid heart beating. Each patient had had greater than 2 episodes of palpitations. No patient had other evidence of heart disease. Standard electrocardiogram was normal (23 of 28 patients), demonstrated ventricular preexcitation (3 of 28 patients) or demonstrated short PR interval (2 of 28 patients). In selected patients, ambulatory monitoring (11 patients) or exercise testing (3 patients) was performed but failed to demonstrate a cause of palpitations. In an effort to initiate tachycardia, a similar transesophageal atrial pacing protocol was performed in each patient. The protocol consisted of: (1) single extrastimuli at progressively closer intervals during sinus rhythm and after an 8-beat pacing train at greater than or equal to 1 cycle lengths and (2) incremental atrial pacing to the point of second-degree atrioventricular block. If this pacing regimen failed to initiate tachycardia, it was repeated during isoproterenol infusion (0.02, 0.05 and 0.1 micrograms/kg/min) and then following intravenous atropine (0.04 mg/kg) administration. During the study, tachycardia was initiated in 20 of 28 patients (71%) (14 of 15 patients greater than 10 years, 6 of 13 patients less than or equal to 10 years; p < 0.01, Fisher's exact test). Electrophysiologic characteristics of induced tachycardia suggested reentry within the atrioventricular node (8 of 20 patients) or orthodromic reciprocating tachycardia (12 of 20 patients). In 3 of 12 patients with orthodromic reciprocating tachycardia, a transition to atrial fibrillation was observed.

    Clinical value of transesophageal atrial stimulation and recording in patients with arrhythmia-related symptoms or documented supraventricular tachycardia--correlation to clinical history and invasive studies. Pehrson SM, Blomstrom-Lundqvist C, Ljungstrom E, Blomstrom P. University Hospital, Lund, Sweden. Clin Cardiol 1994 Oct;17(10):528-34. The main objective of the present study was to evaluate the clinical applicability of transesophageal atrial stimulation (TAS) and recording with regard to inducibility of supraventricular tachycardia (SVT) in patients with either an ECG-documented paroxysmal SVT or a clinical history of palpitations suggesting this disease. A further objective was to assess the inducibility of SVT and to compare the inducibility by TAS with that obtained by an invasive electrophysiologic study (EPS). A total of 64 patients (aged 13-74 years) with ECG-documented paroxysmal SVT (n = 50) or only a history of palpitations (n = 14) was referred for TAS. Preexcitation was present in 35 patients. The study protocol included single and double extrastimuli delivered at a basic paced interval of 500 ms, and incremental atrial stimulation until a cycle length of 275 ms or a second-degree AV block appeared. In 10 patients atropine intravenously was required for induction. The same protocol was used in 34 of the patients who also underwent invasive EPS. TAS was completed in 56 of 64 patients (88%). In this group SVT was induced during TAS in 84% (47/56). Of patients with ECG-documented tachycardia, clinical tachycardia was induced in 90% (35/39) with ECG-documented regular paroxysmal SVT and in 67% of patients (4/6) with ECG-documented atrial fibrillation. In patients without ECG-documented tachycardia, clinically relevant arrhythmia was induced in 73% (8/11). In 30 of 32 patients (94%) with an inducible tachycardia during invasive EPS, it was also possible to induce the tachycardia by TAS.

    Transesophageal study of infant supraventricular tachycardia: electrophysiologic characteristics. Benson DW Jr, Dunnigan A, Benditt DG, Pritzker MR, Thompson TR. Am J Cardiol 1983 Nov 1;52(8):1002-6. Programmed electrical stimulation of the heart to initiate and terminate tachycardia and analysis of the temporal relation between ventricular and atrial activation during tachycardia have been useful in the evaluation of supraventricular tachycardia (SVT). Such techniques have rarely been applied to evaluate infants with SVT. We used a silicone rubber-coated bipolar electrode catheter (15 or 22 mm interelectrode spacing), positioned in the esophagus, for electrical stimulation of the heart and recording of electrograms for the evaluation of 14 infants aged 1 to 84 days with SVT. Three infants had electrocardiographic features of Wolff-Parkinson-White syndrome, and no infant had other manifestations of congenital heart disease. Tachycardia cycle lengths ranged from 180 to 295 ms and ventriculoatrial intervals recorded from the esophagus were 80 to 220 ms. In 12 infants, transesophageal atrial stimulation was used to terminate and initiate SVT using stimuli of 9.9 ms and 10 to 20 mA. Initiation and termination of SVT by electrical stimulation suggest that SVT in infants is due to reentry, and the presence of ventriculoatrial intervals greater than 70 ms further suggests that accessory atrioventricular connections (usually concealed) constitute a portion of the reentry circuit.

    Evaluation of electrophysiological diagnosis of concealed accessory pathway (CAP) during transesophageal atrial pacing. Li Q, Wang Z, Zhou S. Cardiology Division, Second Affiliated Hospital, Hunan Medical University, Changsha. Hunan I Ko Ta Hsueh Hsueh Pao 1997;22(1):49-52. CAP were diagnosed by TEAP using RPE intervals in 55 cases of paroxysmal supraventricular tachycardia (PSVT). There were no obvious CAP manifestations of ECG in those cases, the mean RPE interval during tachycardia was 140 +/- 29 ms, and the lower limit of x +/- 2 s was 82 ms. Among them, the VA intervals were measured by electrocardiophysiological examination in 21 cases. The mean value was 130 +/- 25 ms, and the lower limit of x +/- 2 s was 80 ms. The results suggest that RPE over 82 ms may be an important diagnostic threshold cut off point of atrioventricular reciprocation. 

    Standard of transesophageal atrial pacing to diagnose dual atrioventricular node pathway. Fu H, Lang EP. Hua Hsi I Ko Ta Hsueh Hsueh Pao 1989 Mar;20(1):99-102. In order to assess the diagnostic methods of dual atrioventricular node pathway (DAVNP), we performed transesophageal atrial pacing in 58 patients with palpitation. These patients were classified into two groups, group A comprising 40 patients without broken A-V conduction curve during pacing, compared with group B of 18 patients with broken A-V conduction curve. In our study, both atypical Wenckebach cycle and 3:2 A-V conduction during the increment atrial pacing (IAP) had no significant difference between the two groups (P greater than 0.05). The maximum increments of SR interval in Wenckebach cycle of group A and B during pacing (Wenckebach delta SRmax) were 83.59 +/- 20.92 ms and 125.00 +/- 32.52 ms respectively (P less than 0.001) and at the cut-off point of Wenckebach delta SRmax at 120 ms the specificity and positive predicative value were very high (96.88% and 90.91%), but sensitivity was not so high (71.43%). The minimum increments of RS interval (delta RSmin) in a greater change of SR interval showed a significant difference between the two groups and the specificity and positive predicative value were also high, but the sensitivity was not so high, either (78.57%). We conclude that the diagnostic value of both Wenckebach delta SRmax and delta RSmin, when the SR interval is of greater change during pacing to the DAVNP, is rather significant. As the sensitivity is very low, isolated atypical Wenckebach phenomenon is not as reliable a diagnostic criterion to the DAVNP as previously supposed.  

    Transesophageal versus intracardiac atrial stimulation in assessing anterograde conduction properties of the accessory pathway in Wolff-Parkinson-White syndrome. Favale S, Minafra F, Massari V, Tritto M, Rizzon P.Univ of Bari, Italy. Int J Cardiol 1991 Feb;30(2):209-14. Electrophysiologic intracardiac and noninvasive transesophageal testing, used to evaluate parameters of anterograde conduction across the accessory pathway, the refractory period and shortest atrial cycle length with 1:1 conduction over the pathway, were compared to assess the reliability of the noninvasive technique in identifying patients with Wolff-Parkinson-White syndrome, at risk of rapid ventricular response during atrial fibrillation when this arrhythmia is not inducible. Sixteen patients with Wolff-Parkinson-White syndrome were submitted both to invasive and transesophageal atrial stimulation. We evaluated both the functional and effective refractory periods of the accessory pathway, using the same drive cycle length, and the shortest cycle length with 1:1 atrioventricular conduction over the accessory pathway. There were no differences between the parameters obtained by intracardiac atrial stimulation and by transesophageal atrial stimulation. The two approaches correlated well: mean functional refractory periods of the accessory pathway were 285 +/- 42 msec and 289 +/- 32 msec, respectively (NS, r = 0.88); mean effective refractory periods of the accessory pathway were 267 +/- 41 msec and 271 +/- 32 msec, respectively (NS, r = 0.89); mean shortest cycle lengths with 1:1 conduction over the accessory pathway were 255 +/- 48 msec and 255 +/- 44 msec, respectively (NS, r = 0.94). These data demonstrate the reliability of transesophageal atrial stimulation in estimating the parameters for anterograde conduction across an accessory pathway. These results, and the already documented ability of transesophageal atrial stimulation to induce atrial fibrillation, suggest this noninvasive technique should be taken as a first approach in screening patients with Wolff-Parkinson-White syndrome.

    Transesophageal versus intracardiac atrial stimulation in assessing electrophysiologic parameters of the sinus and AV nodes and of the atrial myocardium. Blomstrom-Lundqvist C, Edvardsson N. Sahlgren's Hospital, Gothenburg, Sweden. Pacing Clin Electrophysiol 1987 Sep;10(5):1081-95. Electrophysiological parameters of the sinus and AV nodes and of the atrial myocardium were assessed with both transesophageal atrial stimulation (TAS) and intracardiac atrial stimulation (ICS) in the same patient during the same study. The study group was comprised of nine men and seven women, aged 45 to 79 years, referred for the evaluation of syncope of possible arrhythmogenic origin. Twelve patients were included for analysis. Autonomic inhibition (AI) was obtained in five patients. The most striking result was the significantly longer AERP with TAS (mean 286 +/- 9 ms) than with ICS (mean 244 +/- 12 ms; p than 0.02). After AI, the AERP was even more prolonged with TAS (mean 332 +/- 20 ms) than with ICS (mean 237 +/- 8 ms; p less than 0.01). Intraatrial and AV nodal conduction times assessed at multiple paced cycle lengths were significantly shorter with TAS than with ICS. There was no difference between TAS and ICS with regard to AVERP, Wenckebach periodicity and H-V intervals. Although a tendency towards shorter sinus node recovery time (SNRT) and sinoatrial conduction time (SACT) was observed with TAS, the difference was not statistically significant. Possible mechanisms of the differences are discussed. It seemed clear that the site of origin of an atrial impulse can have definite effects upon excitability and conduction properties of atrial and AV nodal fibers. Enhanced sympathetic activity during TAS was also suggested. The electrophysiological properties inherent in the TAS technique warrant further elucidation.

    Transesophageal electrocardiography and atrial pacing in acute cardiac care: diagnostic and therapeutic value. Twidale N, Roberts-Thomson P, Tonkin AM. Department of Medicine, Flinders Medical Centre, Bedford Park, SA. Aust N Z J Med 1989 Feb;19(1):11-5. The utility of transesophageal electrocardiography using a bipolar 'pill electrode' was assessed in 17 consecutive patients with tachycardia presenting to our casualty department. Standard 12-lead electrocardiography showed regular narrow QRS tachycardia in 12 patients, and five patients had wide QRS tachycardia. Esophageal atrial electrogram recordings were obtained in 14 patients (82%), and these were helpful in determining the mechanism of tachycardia in 11 patients (78%). Of these 11, seven patients fulfilled criteria for atrioventricular junctional (AVJ) tachycardia based on measurement of the minimum interval between the onset of ventricular depolarisation and earliest atrial (esophageal) activity. One of these patients had presented with a wide QRS tachycardia. The other four patients were diagnosed as having ventricular tachycardia (VT) following diagnosis of AV dissociation. Atrial overdrive pacing, via the pill electrode, successfully reverted four of the nine patients (44%) with narrow QRS tachycardia but no patient with VT. Esophageal recording during tachycardia is a simple, relatively non-invasive technique which is helpful in suggesting the mechanism of tachycardia both in patients with narrow and wide QRS tachycardia, and may have a therapeutic role in patients with AVJ tachycardia. 

    Induction of supraventricular tachycardia (paroxysmal junctional tachycardia and atrial tachycardia) by esophageal stimulation. Brembilla-Perrot B, Spatz F, Khaldi E, Terrier de la Chaise A, Suty-Selton C, Le Van D, Cherrier F, Pernot C. CHU Brabois, Vandoeuvre. Arch Mal Coeur Vaiss 1998;83(11):1695-702. Transesophageal stimulation is tending to replace endocavitary electrophysiological studies in the investigation and treatment of supraventricular tachyarrhythmias. The aim of this study was to determine the sensitivity of this technique in the evaluation of paroxysmal junctional tachycardia (PJT) and atrial tachycardia (AT). Fifty-eight patients with these arrhythmias (PJT, n = 23; AT, n = 35) were investigated under basal conditions and then during Isoproterenol infusions with a protocol using incremental atrial stimulation and programmed atrial stimulation delivering one and two extra-stimuli on two paced rhythms (400-600 ms). It was possible to induce the arrhythmia in the 23 patients with PJT either under basal conditions (n = 16) or during Isoproterenol (n = 7). A reentrant mechanism was suggested in 22 patients by the following findings: position of the auriculogramme with respect to the ventriculogramme, presence or absence of a delaying branch block, situation and morphology of the P wave in lead V1 compared with atrial activation recorded by the esophageal catheter. Atrial tachycardia was induced in 26 patients (74 %), 19 under basal conditions, 6 with Isoproterenol and once after carotid sinus massage. As a conclusion, we can say that the sensitivity of transesophageal stimulation is the same as for endocavitary stimulation.

    Transesophageal study in the diagnostic evaluation of pre-excitation. Favale S, Pitzalis MV, Totaro P, Di Biase M, Rizzon P. Universita degli Studi, Bari. Cardiologia 1991 Aug;36(8 Suppl):75-80. Electrophysiologic non-invasive transesophageal testing is compared to intracardiac study in the management of patients with Wolff-Parkinson-White (WPW) syndrome. Transesophageal study can be reliably used to identify the participation of the accessory pathway in reciprocating supraventricular tachycardia and to determine the anterograde conduction properties of the accessory pathway. Using the shortest pre-excited interval during induced atrial fibrillation, or programmed and continuous atrial transesophageal stimulation can markedly reduce the need of intracardiac evaluation. The greater safety and economy of transesophageal compared to the intracardiac technique justify its wider use in preliminary screening of all WPW patients, unless ablative treatment has been clinically indicated, and in evaluating long-term drug protection against a potential deleterious ventricular response during atrial tachyarrhythmias.

    Evaluation of the informative value and safety of the transesophageal atrial electric stimulation test in patients with unstable stenocardia and myocardial infarction (data of 24-hour ECG monitoring). Merkulova IN, Khakimov AG, Chikvashvili DI, Karpov I. Kardiologiia 1987 Oct;27(10):69-74. Kardiologiia 1987 Oct;27(10):69-74. The effect of the transesophageal pacing test (TEPT) on the occurrence of ventricular arrhythmias and ischemic episodes was examined on the basis of 24-hour ECG monitoring in patients with unstable angina (UA) and myocardial infarction (MI). It is demonstrated that TEPT is a relatively safe test for UA and MI patients (to be performed on day 10-14), which does not provoke severe arrhythmias during and after the testing, but for short paroxysms of ventricular tachycardia seen in 2-4% of the cases. Both painful and painless ST displacements were recorded during the test; ST elevation was only noted in MI patients. The time of ECG baseline recovery was longer in painful ischemic episodes, as compared to painless ones. The TEPT test is a valuable instrument for detecting latent atrioventricular conductivity disorders in UA and MI patients.

    Use of esophageal investigation in the mid-term outcome after radiofrequency ablation of intranodal reentrant tachycardia. Deharo JC, Moustaghfir A, Macaluso G, Le Tallec L, Djiane P. Service de cardiologie, hopital Sainte-Marguerite, CHU Marseille. Arch Mal Coeur Vaiss 1996 Nov;89(11):1375-9. The aim of this prospective study was to assess the medium term results of radio-frequency ablation of intranodal tachycardias by transoesophageal stimulation and recordings. Transoesophageal stimulation was performed on average 9 months after ablation. The anterograde Wenckebach point, the presence of dual nodal conduction and inducibility of nodal tachycardias were determined under basal conditions and after isoproterenol. The follow-up period after ablation was 16.1 +/- 10.2 months. At the time of the oesophageal investigation 25 patients were asymptomatic and 5 had a recurrence of palpitations. The investigation was carried out without complications in all patients and lasted 34.8 +/- 14 minutes. The anterograde Wenckebach point was 340 +/- 78.2 ms and was unchanged compared with the value recorded by endocavitary left atrial stimulation before ablation (332 +/- 63.2 ms). Dual nodal conduction was observed in 19 patients. Nodal tachycardia was inducible in only 2 of the 5 patients with palpitations. Of the asymptomatic patients, 3 had inducible nodal tachycardias after isoproterenol. The authors conclude that oesophageal electrophysiological studies are a simple means of assessing the medium-term results of radiofrequency ablation of intranodal tachycardias. In those patients with a recurrence of symptoms but without documented arrhythmias, failure of radiofrequency ablation may be identified. In addition, the possibility of inducing nodal tachycardias in asymptomatic patients may be detected.

    The diagnostic and treatment characteristics of cardiac arrhythmias in patients with the premature ventricular excitation syndrome. Lipnitskii TN, Otkalenko IuK, Randin AG, Stepaniuk AV. Vrach Delo 1991 Oct;(10):83-6. Studied were 24 patients with the syndrome of premature excitation of the ventricles. In 18 of them transesophageal electrophysiological examination was carried out. Reciprocal paroxysmal tachycardia was revealed in 16 patients (orthodromic form--in 14, antidromic--in 2 patients). Cardiac fibrillation with a cardiac contraction rate of 320-340 per minute was noted in 2 patients. Difficulties are noted in the differential diagnosis of antidromic form with ventricular paroxysmal tachycardia and risk of development of ventricular fibrillation in auricular fibrillation. The authors propose a method of diagnosis of latent forms of the syndrome of premature excitation of the ventricles using short-term pharmacological block of atrioventricular conduction in intravenous administration of ATP.

    Transesophageal atrial stimulation in 168 patients.Arribada A; Alfaro M; Kuhne W; Valdivia L. Hospital Clinico San Borja-Arriaran. Rev Med Chil (Chile), Apr 1992, 120(4) p383-9. Transesophageal atrial stimulation was performed in 168 patients, 95 males and 73 males, 20 to 81 years of age. The indication for atrial stimulation was the study of some bradyarrhythmia in 109 and ischemic heart disease in 59. An esophageal catheter was introduced through the nose and placed at a spot where a bimodal P wave was obtained. Stimulation was performed using a baby Medtronic stimulator coupled to a Vygon amplifier delivering an output of 30 volt. Sinus node recovery time was measured after 2 to 3 min of stimulation at different rates. Wenckebach and 2:1 A-V block as well as ST deviation were determined. Sick sinus syndrome was diagnosed in 41 cases through altered sinus node recovery time and/or secondary pauses; 35 patients showed Wenckebach rhythm at a stimulation rate over 120 per min; 2: 1 A-V block appeared in 22. Ischemic ST-T changes were produced in 20 subjects. No complications were observed, confirming this approach as a simple and effective way to achieve atrial stimulation for diagnostic purposes.

    Esophageal pacing in children. 38 consecutive cases. Lucet V, Do Ngoc D, Denjoy I, Saby MA, Toumieux MC, Batisse A. Centre de Cardiologie Infantile. Arch Fr Pediatr 1990 Mar;47(3):185-9. On the occasion of a preliminary series of 38 cases, the authors review the esophageal pacing technique and its main indications. On the therapeutic level, the esophageal lead may be successfully used to decrease supraventricular tachycardias due to reentry (typical or atypical flutter, reciprocating nodal tachycardia with or without WPW). As a means of investigation, esophageal pacing is overall useful to diagnose undocumented paroxysmal tachycardia fits (palpitations), to evaluate the refractory stage of an accessory pathway (WPW) or to assess the refractory stage of antiarrhythmia medications. This investigation may also be used to assess the sinusal function, the atrioventricular conduction (Wenckebach point) and the spontaneous rhythm of atrioventricular blocks after pacemaker insertion. Due to the technical improvements achieved, esophageal pacing may be used presently in pediatric units taking care of children with arrhythmias.

    Efficacy and risks of medical therapy for supraventricular tachycardia in neonates and infants. Weindling SN, Saul JP, Walsh EP. Children's Hospital, Boston, Mass., USA. Am Heart J 1996 Jan;131(1):66-72. To assess the efficacy and safety of current pharmacologic therapy for supraventricular tachycardia (SVT) in infants, we reviewed 112 infants treated between July 1985 and March 1993. The SVT mechanism was determined by esophageal electrophysiologic study and involved an accessory pathway in 86, atrioventricular (AV) node reentry in 10, atrial muscle reentry in 11, and an ectopic atrial tachycardia in 5 patients. Of six infants not treated, none had clinical recurrences of SVT. Of the 106 patients treated, 70% remained free of tachycardia while receiving digoxin, propranolol, or both. Class I antiarrhythmic agents were necessary for 13 patients, and class III agents were required for another 13 infants. Verapamil was used in one infant with AV node reentry tachycardia. Nine infants with complex clinical presentations were believed to have failed medical management and underwent radiofrequency ablation. Five patients died, four of complications related to structural heart disease and one shortly after radiofrequency ablation was performed. No deaths appeared to be related to antiarrhythmic medications. No drug-related side effects requiring medication change occurred, and no proarrhythmia was observed. Thus medical therapy appears to be effective and safe in infants with SVT. Radiofrequency ablation should be reserved for rare infants who fail aggressive medical regimens or when the situation is complicated by ventricular dysfunction, severe symptoms, or complex congenital heart disease.

    Transesophageal electropharmacologic test in a newborn with familial Wolff-Parkinson-White syndrome. Colloridi V, Boscioni M, Patruno N, Pulignano G, Critelli G. University of Rome La Sapienza, Italy. Pediatr Cardiol 1990 Oct;11(4):213-5. A newborn infant with familial Wolff-Parkinson-White (WPW) syndrome presented with a supraventricular tachycardia of 300 beats/min, refractory to digoxin and flecainide administration. Serial electropharmacologic tests were performed via the esophagus before and during oral therapy with verapamil at 40, 80, and 60 mg daily. Before treatment, tachycardia could be induced with programmed stimulation. A regimen of verapamil at 60 mg daily, which resulted in the initiation of nonsustained (less than 10 s) reciprocating tachycardia only, without clinical recurrences, was identified as suitable long-term oral therapy. The efficacy of this drug regimen in preventing episodes of tachycardia was confirmed during a 1-month follow-up period. It is concluded that transesophageal atrial pacing is a useful, noninvasive means of selecting treatment in neonates with supraventricular tachycardia, when nonconventional drugs are considered for prophylaxis.

    The esophageal approach in rhythmology. Mabo P, Gras D, Leclercq C, Daubert C. CHRU, 2, Rennes. Arch Mal Coeur Vaiss 1995 Dec;88 Spec No 5:43-7. The possibility of detecting the electrical activity of the heart from the oesophageus has been recognised for nearly a century. On the other hand, transesophageal pacing has only been really developped in the last fifteen years, which explains the recent interest for this technique in clinical practice. Easily put into practice, but not always well tolerated, the oesophageal approach has many uses in rhythmology. The principal diagnostic applications are in unlabelled tachycardias whether with narrow or wide QRS complexes, the evaluation of the Wolff-Parkinson-White syndrome, the study of sinus node function or nodal conduction. The therapeutic applications are dominated by the reduction of supraventricular tachycardias especially atrial flutter, with a success rate similar to that of endocavitary stimulation. The facility of realisation, especially at the patient's bedside, without need for fluoroscopie control, makes it a useful tool in emergencies, especially if the endocavitary approach cannot be used. The only reserve is the painful character of pacing in some patients.

    The diagnostic value of esophageal ECG and transesophageal atrial stimulation in paroxysmal supraventricular tachycardia. Pehrson SM, Blomstrom P.Kardiologkliniken, Lunds Lasarett, Sverige. Ugeskr Laeger 1991 Nov 25;153(48):3403-7. Paroxysmal supraventricular tachycardia (PSVT) includes a group of common arrhythmias. The diagnosis should be based on 12-lead ECG. Oesophageal ECG, which registers mainly left-sided posterior atrial activity may be of value for further assessment of the arrhythmic mechanism in determination of the time relationship between atrial and ventricular signals. A ventriculoatrial interval during PSVT measured by oesophageal ECG of under 70 ms is evidence of atrioventricular nodal re-entry tachycardia while an interval of over 70 ms suggests orthodromic reciprocating tachycardia with participation of an accessory atrioventricular pathway. Transoesophageal atrial stimulation (TAS) via an electrode catheter is possible in approximately 90% of the patients with PSVT. TAS requires greater quantities of energy than endocardial stimulation and is associated with slight to moderate retrosternal discomfort. The method renders possible both programmed stimulation with the object of inducing arrhythmia and in stopping the majority of cases PSVT, with the exception of atrial fibrillation. The method is relatively simple, non-invasive, requires few resources and can be carried out on outpatients.

    Transesophageal electric heart stimulation in the diagnosis of paroxysmal supraventricular tachycardias. Smetnev AS, Grosu AA, Sokolov SF, Golitsyn SP. Kardiologiia 1983 Nov;23(11):13-8. Thirty-one patients with paroxysms of supraventricular tachycardia (SVT) were examined using trans-esophagus electrical stimulation of the left atrium. SVT paroxysms were provoked in 23 patients. An analysis of the esophagus electrogram recorded revealed SVT paroxysms in the presence of the latent Wolff-Parkinson-White (WPW) syndrome in 12 patients, orthodromic SVT in the presence of the WPW syndrome in seven, and paroxysmal reciprocal atrioventricular node tachycardia in four patients. Paroxysms were also induced in three out of 8 patients with atrial fibrillation. Two patients displayed a fall in the ST segment.

    Induction of ventricular tachycardia by esophageal stimulation. Apropos of 2 cases. Kieny JR, Roul G, Sachs D, Mossard JM, Bareiss P, Sacrez A/ CHU Hautepierre, Strasbourg. Arch Mal Coeur Vaiss 1991, 84(11):1587-90. The utility of transesophageal atrial pacing in sustained left ventricular tachycardia is reported in two cases. A 46 year old man without any apparent cardiac disease presented with invalidating but undocumented palpitations. Transesophageal atrial pacing with isoproterenol infusion induced wide complex tachycardia with a right bundle branch block morphology and left axis deviation. Atrio-ventricular dissociation was observed and it was possible to reduce the ventricular complex width by rapid transesophageal atrial pacing: the tachycardia was terminated by an injection of verapamil. It was not possible to reinduce the tachycardia after treatment with atenolol 100 mg/day, introduced because of the catecholinergic nature of the arrhythmia. The patient is symptom free after 2 years of treatment with this drug. Regular wide complex tachycardia with right bundle branch block and left axis deviation without any detectable atrial activity was recorded in a 50 year old man without known cardiac disease. Transesophageal atrial pacing with isoproterenol infusion induced an identical tachycardia. The tachycardia started after a normally conducted atrial extrastimulus followed by ventriculo-atrial dissociation and it was possible to overdrive with atrial pacing. The tachycardia could not be reinduced after treatment with atenolol and the patient is asymptomatic 12 months later. These reports show that it is possible to study certain ventricular tachycardias by transesophageal atrial pacing. The efficacy of antiarrhythmic therapy can be controlled simply by this non-invasive technique.

    Diagnostic and therapeutic potential of transesophageal cardiac pacing in the management of patients with arrhythmias. Behulova R; Margitfalvi P; Hatala R. Bratisl Lek Listy (Slovakia), Nov 1997, 98(11) p589-93 BACKGROUND: Transoesophageal cardiostimulation is a semiinvasive method of stimulation of atrii enabling the performance of the programmed atrial stimulation without the inevitability of an invasive vascular approach. This method was used in 124 patients with the following indication spectrum. Diagnostic indications: total 82%, paroxysmal supraventricular tachycardia (SVT), and WPW sy-22%, tachycardia with wide QRS-complex-8%. SSS syndrome and bradycardia-20%, sycopes and collapses with unclear etiology-13%, palpitations-11%, control of antiarrhythmic therapy-4%, and other states-6%. Therapeutic indications: total-18%, versions of paroxysmal SVT and flutter of atrii. RESULTS: The patients with SVT were assumed to develop the arrhythmogenic mechanism--AV nodal re-entry tachycardia in 80%, orthodrome AV-re-entry tachycardia in 30%, and flutter of atrii in 20%. All patients with WPW-syndrome were stratified by the use of this method. The origin of this state from ventricular arrhythmia was verified in 40% of patients with tachycardia with a wide QRS complex. In coincidence with other indications, the diagnostic benefit of transoesophageal cardiostimulation was evaluated as follows: syncopes-68%, palpitations-64%, syndrome SSS and bradycardia-48%. The therapeutic indication of SVT version and flutter of atrii, was totally successful in 40%, partly successful in 45% and unsuccessful in 15% of patients. CONCLUSION: Transoesophageal cardiostimulation has contributed to the assessment of the diagnosis in 69% of patients and has acutely managed arrhythmia in 85% of cases. According to our experience, this method is effective in the initial management of patients with arrhythmia. Its low technical and economic demands make its wider utilisation appropriate in clinical practice of internal medicine.

    Transesophageal atrial stimulation. Origgi MS, Gallo Junior L, Godoy RA, Marin-Neto JA, Maciel BC. Universidad de Sao Paulo, Brasil. Arch Inst Cardiol Mex 1990;60(3):241-51. (Published erratum appears in Arch Inst Cardiol Mex 1991;61(1):91). Considering that catheterization of the esophagus is a relatively easy procedure, we studied the electrical transesophageal atrial stimulation in ninety patients (age range 15 to 75 years (mean 42 +/- 9 years). A multipolar electrode catheter was introduced through the nose into the esophagus of each patient and fixed in position at a site where the simultaneous recording of intraesophageal unipolar electrocardiographic derivations showed the greatest P wave potentials. Electrical atrial capture through the esophagus was obtained at frequency values higher than that of the heart, with lower voltages needed for atrial stimulation at the site in which the unipolar recording of the intraesophageal P wave was of highest amplitude. The difference of potential used was between 6 and 30 volts, with the highest values corresponding to patients with megaesophagus, whereas values below 15 volts were tolerated without major discomfort. Electric pulses of more than 10 ms duration did not significantly reduce the intensity of electric current needed to produce the atrial command. The stimulation bipole (area to be stimulated per pole, 0.72 cm2) had an interpolar distance of 22 or 30 mm, our overall experience showing that distances up to 44 mm did not require higher voltages. No cases of esophageal damage or severe arrhythmia were reported due to stimulation. In the present study, programmed transesophageal stimulation proved to be a good option for the evaluation of sinus node function and for the study and reversal of paroxysmal supraventricular tachycardia attacks by a reentry mechanism, representing in some cases an alternative approach for the study of atrioventricular conduction.

    Clinical and prognostic value of evaluation of atrial vulnerability in an electrophysiological endocavitary and transesophageal study. Delise P, Bonso A, Allibardi P, Millosevich P, Zerio C, D'Este D, Rigo F, Gasparini G, Coro L, Raviele A.G Ital Cardiol 1990 Jun;20(6):533-42. Atrial fibrillation or flutter is frequently inducible during endocavitary or transesophageal electrophysiologic study. However, its clinic and prognostic significance has not yet been clarified. We studied 443 patients: 276 underwent endocavitary electrophysiologic study, 228 underwent transesophageal electrophysiologic study and 61 underwent both methods. In 343 of them a satisfactory echocardiogram was obtained. Patients were divided in three groups: gr. I, 93 patients with documented episodes of paroxysmal atrial fibrillation or flutter; gr. II, 257 patients with or without heart disease without clinical atrial fibrillation or flutter; gr. III, 93 symptomatic or asymptomatic Wolff-Parkinson-White patients without clinical atrial fibrillation or flutter. Gr. I included patients without overt heart disease (20), with WPW (11), mitral valve prolapse (4), and miscellaneous (58). Gr. II included patients without overt heart disease (49), with concealed Kent bundles (7), Mahaim (1) or James fibers (1) mitral valve prolapse (6), sick sinus syndrome (40), miscellaneous (91), or syncope of an unknown origin (62). Atrial vulnerability was evaluated both by endocavitary and transesophageal electrophysiologic study using two different protocols; the first protocol was moderately aggressive (prot. A), while the second was aggressive (prot. B). Endocavitary electrophysiologic study. Prot. A: single and double extrastimuli at the three heart rates (sinus, 100 and 150/m'), 10/m' incremental atrial pacing from 160 to 250/m; prot. B: prot. A + incremental atrial pacing from 260/m' up to 2:1 St-A block. Transesophageal electrophysiologic study. Prot. A: 10" atrial burst at 100-600/m' prot. B: prot. A + 6-9" increasing rate bursts from 200 to 800/m'. End point of all protocols: initiation of greater than 1' atrial fibrillation or atrial flutter. RESULTS: Endocavitary electrophysiologic study. A greater than 1' atrial fibrillation or atrial flutter was induced with the two protocols respectively in 67% (52/78) and 85% (51/60) of gr. I, in 17% (26/150) and 36% (38/105) of gr. II and in 35% (17/48) and 44% (21/48) of gr. III (gr. I vs gr. II p less than 0.001 for prot. A and p less than 0.01 for prot. B; gr. II vs gr. III p less than 0.001 for prot. A and NS for prot. B). Induced atrial fibrillation or atrial flutter using the two protocols had a greater than 5' duration respectively in 83 and 78% of gr. I, 62 and 42% of gr. II and in 41 and 38% of gr. III.

    Heart rate variability. Is it influenced by disturbed sinoatrial node function? Sosnowski M, Petelenz T. III Clinic of Cardiology, Silesian Medical School, Silesian Heart Center, Katowice, Poland. J Electrocardiol 1995 Jul;28(3):245-51 Analysis of heart rate variability (HRV) is commonly used to assess the influences of the autonomic nervous system on the heart; however, its relation to the sinoatrial node function has not been clearly defined. In this study, the authors performed HRV investigations in 150 patients (51 women and 99 men; mean age, 49 years; range, 17-80 years) in whom clinical observation and electrophysiologic transesophageal studies proved sinoatrial node dysfunction (SAND) and in 50 healthy control subjects (19 women and 31 men; mean age, 37 years; range, 15-60 years). All examined subjects underwent transesophageal left atrial overdrive pacing for the evaluation of sinus node recovery. The HRV analysis was based on 1-minute esophageal electrocardiographic recordings. Two time-domain HRV variables were measured: variability range ([VR]) the difference between the longest and the shortest sinus cycle length, divided by basic sinus cycle length) and beat-to-beat variability ([DSCL]--the maximum difference between any two consecutive sinus cycle lengths) during a 1-minute recording. Because of the known effects of age and basic sinus cycle, statistically adjusted means of VR and DSCL were compared. In patients suffering from SAND, DSCL was significantly higher than in the control subjects (198 +/- 206 vs 98 +/- 89 ms, respectively), as was VR (30.3 +/- 23.3% vs 20.9 +/- 121.1%).

    Evaluation of electrophysiologic properties of the heart atrium in patients with electrically induced atrial fibrillation. Owczarek I, Banasiak W, Metner E, Fuglewicz A, Telichowski A, Lacheta W, Klaniewski T. Pol Arch Med Wewn 1997;98(9):197-205. Paroxysmal palpitation is a frequent non-specific symptom observed in clinical practice. It is not always possible to identify the arrhythmogenic cause of this complaint. The induction of paroxysmal atrial fibrillation (PAF) during transoesophageal pacing (TEP) was found to be particularly useful when arrhythmia paroxysms were not evidenced by standard electrocardiography or by 24-hour Holter monitoring. The objective of the present study was a comparative assessment of the electrophysiological parameters obtained from a patient group with PAF induced during TEP and from a patient group with no arrhythmia, in order to determine the hazard of spontaneous PAF occurrence. The study included 116 patients complaining of palpitations who underwent TEP. Of these, 53 were selected (34 males and 19 females; mean age, 47.6 +/- 13.1) in whom a sustained PAF episode (> 30 sec) had been induced during TEP. These patients are referred to Group I. Group II (control) comprised the remaining 63 patients (38 males and 25 females; mean age 45.5 +/- 8.5) in whom no PAF episode had been induced during TEP. All patients (Group I and Group II) underwent echocardiography, 24-hour Holter monitoring, exercise test and TEP. During TEP the following parameters were evaluated: left atrial effective refractory period (AERP), sinoatrial conduction time (SACT), maximal and corrected sinus node recovery time (SNRT and CNRT), Wenckebach periodicity (WP) and mean cycle duration (CD). Thus, the AERP value amounted to 299.8 +/- 42.4 msec and 259.5 +/- 54.9 msec (p < 0.001) for Group I and Group II, respectively. The SACT and SNRT values totalled 132.3 +/- 45.1 msec and 1011.1 +/- 165.6 msec in Group I, and 103.2 +/- 29.9 msec and 838.3 +/- 172.7 msec in Group II, respectively (p < 0.001). Compared to the control (235 +/- 95.7 msec; 200.3 +/- 64.9 msec, respectively), the group of patients with electrically-induced PAF (Group I) showed significantly longer CNRT (383.4 +/- 172.5 msec, p < 0.001) and WP (350.8 +/- 59.3 msec, p < 0.001). The study had led to the following finding: patients with electrically-induced PAF had significantly longer left effective refractory periods, sinoatrial conduction times, maximal and corrected sinus node recovery times and Wenckebach periodicities.

    Wolff-Parkinson-White syndrome. Value of transesophageal atrial stimulation coupled with exercise test for the study of anterograde conduction in the accessory pathway. Cebron JP, Le Marec H, Victor J, Chevallier JC, Borgat C, Godin JF. Hopital Laennec, Nantes. Arch Mal Coeur Vaiss 1989 Feb;82(2):159-66. In patients with Wolff-Parkinson-White syndrome the anterograde conduction properties of the accessory pathway determine the ventricular rate in case of atrial fibrillation (AF). Anterograde conduction in the accessory pathway was evaluated in 20 patients (mean age 31 years) by means of transoesophageal atrial pacing with increasing frequency (up to 460 per minute), first at rest, then during exercise on an ergometric bicycle and upon immediate recovery. The exploration was completed by a search for the disappearance of pre-excitation during exercise and after an intravenous injection of ajmaline 1 mg/kg. The shortest cycle (SC) of atrial pacing with 1:1 conduction by the accessory pathway regularly decreased by 80 +/- 26 ms (n = 18), i.e. 27 p. 100 of its value at rest. At immediate recovery SC increased by 40 +/- 53 ms (n = 9). Atrial fibrillation was induced at rest and/or during exercise in 12 patients. The shortest interval (SI) between two pre-excited ventricular complexes was 290 +/- 80 ms (n = 8) at rest and 244 +/- 53 ms (n = 8) during exercise. With a substantial group of values (n = 12) there was good correlation between SC and SI both at rest and during exercise. With a smaller group of values (n = 3) SI was clearly greater than SC, suggesting a concealed conduction in the accessory pathway during atrial fibrillation. Disappearance of pre-excitation during exercise was observed in 4 patients, 3 of whom had a short (less than 250 ms) SC and/or SI.

    Usefulness of transesophageal electrophysiological study during the ergometric test in the evaluation of supraventricular paroxysmal tachycardia occurring during exertion. Delise P, D'Este D, Bonso A, Allibardi P, Raviele A, Di Pede F, Piccolo E. Ospedale di Mestre, Venezia. G Ital Cardiol 1989 Dec;19(12):1094-104. Transesophageal electrophysiologic study has recently been proposed for the evaluation of supraventricular arrhythmias. In this report we present 13 cases, with palpitations occurring only during effort, due to a suspected supraventricular tachycardia, in which the usefulness of the transesophageal electrophysiologic study performed during stress test was evaluated. Of these 13 patients, nine were male and four were female, mean age was 29 yrs. Twelve cases had no heart disease, one had a moderate mitral valve insufficiency. Nine cases had a normal ECG, four had a WPW pattern. In 9/13 cases no significant arrhythmia was ever documented, in 1/13 ventricular premature beats were present in the basal ECG, in 1/13 a atrial fibrillation and in 2/13 a supraventricular reciprocating tachycardia was recorded. In all cases a maximal exercise test and a 24-hour Holter monitoring were performed. In all pts a transesophageal electrophysiologic study was performed both at rest and during extra-stimuli and incremental atrial pacing. The end point of transesophageal study was the induction of a sustained (greater than 30") supraventricular tachycardia. RESULTS. Maximal exercise test was negative in 11/13 cases; it showed ventricular premature beats in one case and initiated a supraventricular tachycardia in one. The 24 hour Holter monitoring was negative in 12/13 cases while it showed frequent ventricular premature beats in one. Resting transesophageal electrophysiologic study revealed dual A-V nodal pathways in six pts: in one of them a junctional re-entry was induced; in two a single echo beat was observed, while in three no reentry was observed. In three cases a supraventricular tachycardia was induced which was sustained in one and unsustained (7" and 24") in two cases. In 4 cases transesophageal electrophysiologic study gave no information. Transesophageal stimulation during exercise induced a greater than 30" reciprocating tachycardia in all patients, at work loads of 30-180 watts. Six pts had an intranodal tachycardia (V-A less than 70 msec) a further six pts had a atrioventricular tachycardia involving a Kent bundle (V-A greater than or equal to 70 msec), which was concealed in two, and one had a atrial tachycardia. In four cases (3 with intranodal and 1 with atrioventricular tachycardia), exercise transesophageal study was repeated after chronic therapy with betablockers (sotalol 240 mg/die or metoprolol 200 mg/die). In all cases, after therapy, the induced tachycardia had a longer cycle and in two cases it was induced at a higher work load. In a further two cases flecainide (200 mg/die) was tested. In one case (with atrial tachycardia), the arrhythmia was no longer inducible after therapy, in another case (with intranodal tachycardia) the drug had no effect. CONCLUSIONS. In patients with paroxysmal supraventricular tachyarrhythmias occurring during effort the basal ECG is normal or shows a WPW pattern. The maximal exercise test and 24 hour Holter monitoring give no information in over 90% of cases.

    Induction of supraventricular tachyarrhythmia at rest and during exercise with transoesophageal atrial pacing in the electrophysiological evaluation of asymptomatic athletes with Wolff-Parkinson-White syndrome. Vergara G, Furlanello F, Disertori M, Inama G, Guarnerio M, Bettini R, Cozzi F. Division of Cardiology and Arrhythmologic Centre, S. Chiara Hospital, Trento, Italy. Eur Heart J 1988 Oct;9(10):1119-25. Even today there is controversy as regards the best approach to asymptomatic or slightly symptomatic athletes with the WPW syndrome as regards fitness for sports activity, especially in some countries where the doctor is responsible for certifying sports fitness. This study concerns 84 asymptomatic or slightly symptomatic athletes (66 males, 18 females, mean age 21.7 years, range 12-44 years) who underwent a stimulation protocol the end-point of which was the induction of atrial fibrillation (or, if not possible, atrial tachyarrhythmia) in the basal state and during bicycle stress test with transesophageal atrial pacing. The 81 athletes in whom the end-point was reached were divided into two groups: Group I includes the 32 athletes with the shortest R-R interval between pre-excited beats less than or equal to 240 ms in the basal state and/or less than or equal to 210 ms during bicycle ergometer test, Group II includes the other 49 patients. The evaluation during exercise was not carried out in four athletes because of serious haemodynamic compromise due to the arrhythmia induced in the basal state. Only 21/32 athletes would have been included in Group I if only evaluated in the basal state. In 30/81 athletes (37%), there was discrepancy between the result of stimulation and the result of the usual non-invasive evaluation (Holter monitoring, ergometric stress test, ajmaline test). On average, 40 min are required for the performance of the study protocol except when the induced arrhythmia lasts more than 5 min.

    Outcome of Wolff-Parkinson-White syndrome in children. Transesophageal study of anterograde permeability of the accessory pathway and of atrial vulnerability. Villain E, Attali T, Iserin L, Aggoun Y, Kachaner J. Hopital Necker-Enfants Malades, Paris. Arch Mal Coeur Vaiss 1994 May;86(5):649-52. Twenty-nine children with the Wolff-Parkinson-White syndrome (WPW) were evaluated by transoesophageal electrophysiological studies to determine the quality of anterograde-conduction in the accessory pathway and the atrial vulnerability. The study group included 15 neonates, 1 to 30 days old, and 14 children from 5 to 15 years of age; Anterograde conduction through the bundle of Kent was tested by incremental transoesophageal atrial pacing and by the determination of the shortest conducted cycle with preexcited RR waves; bursts of atrial pacing were then used to try to trigger an atrial arrhythmia. In the group of the 15 neonates, 11 had accessory pathways capable of conduction to the ventricules at frequencies > 300/min (stimulation cycle < or = 2.00 ms) but no atrial arrhythmias could be induced. The older children had slower conduction in the accessory pathways with the shortest conducted cycle length > 200 ms in 11/14 cases; on the other hand, atrial fibrillation was easily induced in 4 children, all over 12 years of age. The risk of syncope by rapid conduction of an atrial arrhythmia through the accessory pathway is negligeable in young children, including those on digoxin. This study suggests that this low risk is explained more by the absence of atrial vulnerability than by the electrophysiological properties of the accessory pathways.

    Transesophageal stimulation of the left atrium in children with arrhythmia. Bieganowska K, Kubicka K, Stopczyk M, Oficjalska B. Pediatr Pol 1989 May;64(5):295-303. The conduction system of the heart was studied in 41 patients with cardiac arrhythmias by oesophageal stimulation of the left atrium. 31 children had a history of paroxysmal supraventricular tachycardia, 5 supraventricular or/and ventricular premature beats and 5 were studied because of suspected bradycardia-tachycardia syndrome. In all patients stimulation of the left atrium was well tolerated. There were no side effects or complications. The results showed that oesophageal stimulation of the left atrium was a faithful noninvasive method in diagnostic studies of the conduction system of the heart. This method was effective in studying the mechanism of supraventricular arrhythmias.

    Cardiovascular collapse in infants: association with paroxysmal atrial tachycardia. Gikonyo BM, Dunnigan A, Benson DW Jr. Pediatrics 1985 Dec;76(6):922-6. Four infants, aged 16 to 28 days (mean 23 days), were seen in the emergency room with acute cardiovascular collapse and with normal heart rate and rhythm. During evaluation for cardiovascular collapse, no infant had sepsis; cardiac assessment revealed normal intracardiac anatomy but global cardiac chamber enlargement and poor left ventricular systolic function, which resolved with supportive treatment. However, three of the four infants demonstrated ventricular preexcitation on their surface electrocardiogram and, subsequently, two infants had transient episodes of tachycardia. During a transesophageal pacing study to evaluate inducibility and electrophysiologic characteristics of tachycardia, sustained tachycardia was initiated in all four infants. Reentrant tachycardia used an accessory atrioventricular connection as evidenced by the presence of preexcitation during sinus rhythm (three infants), the ability to initiate and terminate tachycardia by programmed electrical stimulation (four infants), minimum ventriculoatrial interval recorded in the esophagus (V-Aeso) exceeded 70 ms (four infants), transient bundle branch block during tachycardia prolonged the cycle length and the V-Aeso by 30 to 50 ms (three infants). Findings in these infants suggested prior episodes of prolonged tachycardia as the probable etiology of the cardiovascular collapse.

    Transesophageal atrial stimulation in hypothyroidism. 1. Studies of cardiac automatism. Kocot E, Jonderko G, Marcisz C. Z Gesamte Inn Med 1983 Jan 1;38(1):12-5. Electrophysiologic investigations of the heart with the aid of transoesophageal atrium stimulation (extra-stimulus technique and overdriving stimulation) have been performed in 19 patients with primary hypothyroidism and a normal electrocardiogram in standard linkages. The control group comprised 34 healthy persons. In 68% of patients with hypothyroidism there have been stated a prolonged refraction time of the atrium-ventricular and intraventricular conductivity system while in the case of healthy persons an analogic type of changes has been observed only in 12%. Atrium overdriving stimulation has shown a decrease of the atrium-ventricular conductibility at a frequency below 130/min and in 74% of the patients with hypothyroidism the blocking assumed a shape of Wenckebach's periodic.

    Transesophageal atrial stimulation in hypothyroidism. II. Effect of hypothyroidism therapy on cardiac automatism. Jonderko G, Kocot E, Marcisz C. Z Gesamte Inn Med 1983 Jan 1;38(1):15-7. Investigations of the heart automatism were carried out in 8 persons with primary hypothyroidism before therapy and after euthyroid status procurement. In order to determine the electrophysiologic parameters there has been applied the transoesophageal atrium extrastimulus technique and the overdriving stimulation. There has been stated a positive effect of the thyroid function compensation upon the atrium refractory period, the atriumventricular conductibility and the refractory time of the total conductivity system. The authors suggest, that investigation, in which transoesophageal atrium stimulation has been applied, may belong to the methods of tracing the effect of hypothyroidism therapy.

    Long-term follow-up of patients with inducible supraventricular tachycardia treated with flecainide or propafenone: therapy guided by transesophageal electropharmacologic testing. Furlanello F, Guarnerio M, Inama G, Vergara G, Del Greco M, Bertoldi A, Dallago M. Divisione di Cardiologia e Centro Aritmologico, Ospedale S. Chiara, Trento, Italy. Am J Cardiol 1992 Aug 20;70(5):19A-25A. We report our experience with flecainide and propafenone therapy for inducible supraventricular tachycardias and paroxysmal supraventricular tachycardias due to atrioventricular (AV) nodal reentry or the Wolff-Parkinson-White syndrome. We performed an electropharmacologic test (ET) that consisted of first inducing a clinical arrhythmia by transesophageal atrial pacing (TAP) protocol. This was followed by intravenous drug administration and TAP reevaluation, either after acute intravenous administration or in oral steady-state. We used ET with flecainide and/or propafenone to study 2 groups of patients at least 3 years before the long-term clinical observation period. The first group was comprised of 58 patients with reciprocating tachycardias--due to AV node reentry in 17 (29.3%) and anomalous pathway in 41 (70.7%). Twelve (29.3%) of the latter had reciprocating tachycardias, 15 (36.6%) had atrial fibrillation, and 14 (34.2%) had both arrhythmias. During ET, flecainide was administered to 42 patients, and the ET was considered positive in 28 (66.7%). Propafenone was administered to 32 patients, with positive results in 15 (46.9%). In 15 patients, both flecainide and propafenone were tested, 8 receiving flecainide after a negative ET with propafenone, and 7 receiving propafenone after a negative ET with flecainide. In the first group, the ET was positive in 7 (87.5%), and in the second group, it was positive in 3 (42.9%). In a follow-up of 40.1 +/- 11 months, 38 (65.5%) patients had positive outcomes, 5 (8.6%) had to stop receiving the drugs because of side effects, 3 (5.2%) stopped because of inefficacy, and 12 (20.7%) dropped out. 

    Asymptomatic pre-excitation. Identification of potential risk using transesophageal pacing. Patruno N, Critelli G, Pulignano G, Urbani P, Villanti P, Reale A. Cardiologia 1989 Sep;34(9):777-81. Noninvasive assessment of the conducting capability of the accessory pathway (AP) in asymptomatic patients with a preexcitation ECG pattern is desirable, since life-threatening arrhythmias and sudden death may be the first manifestation of the Wolff-Parkinson-White (WPW) syndrome. To investigate whether in patients with preexcitation ECG pattern the absence of clinical arrhythmias excludes the potential for rapid ventricular responses, transesophageal atrial pacing (TAP) was performed in 11 subjects (9 male, 2 female), aged 5 to 43 years. The extrastimulus technique was used in order to define the refractory periods and in the attempt to induce reciprocating tachycardia. Incremental TAP up to the occurrence of block in the AP was instituted, and attempts to induce atrial fibrillation (AF) with rapid burst pacing were made. One to one atrioventricular conduction over the AP at progressively increased cycle lengths (CLs), and the shortest R-R interval between pre-excited beats during induced AF were evaluated. The following findings were considered predictors of potential life-threatening arrhythmias: 1) anterograde refractory period of the AP equal to or shorter than 250 ms; 2) one to one AP conduction at CLs shorter than 300 ms; 3) shortest R-R interval, during induced AF, less than 250 ms. Sustained reciprocating tachycardia could not be induced in all patients in spite of the use of the use of an aggressive stimulation protocol. The anterograde refractory period of the AP could not be defined in 9 patients. In the remaining 2 this parameter was longer than 250 ms. In 8 patients (72%), the shortest CL maintaining 1:1 AP conduction ranged from 220 to 280 ms (mean 253 +/- 19).

    Potential of the method of transesophageal stimulation of the left atrium. Zhdanov AM, Gukov AO, Shanaeva NS. Ter Arkh 1989;61(4):67-74. The authors provide the results of examining the conduction system of the heart in 623 patients with different disorders of heart conduction and rhythm by means of transesophageal pacing (TEP). The non-invasive electrophysiological examination of patients with sick sinus syndrome with latent disorders of atrioventricular (AV) conduction, and with supraventricular tachyarrhythmias turned out to be of high diagnostic value, inducing no complications. Application of programmed TEP (scanning extrastimulus on basis pacemaking) employed by the authors for the first time during TEP considerably widens the diagnostic possibilities of the technique permitting the measurement of the refractory periods of the conduction system (the refractory periods of the sinus node, atria, and AV-conduction system along normal and additional pathways), the performance of the trigger and removal of supraventricular arrhythmias with diagnostic and treatment purposes in view. The use of TEP for the treatment of patients with the syndrome of the prolonged QT interval and ventricular premature heart beat accelerates the choice of adequate antiarrhythmic therapy and raises its efficacy.

    Electrophysiological significance of QRS alternans in narrow QRS tachycardia. Pulignano G, Patruno N, Urbani P, Greco C, Critelli G. Univ of Rome. Pacing Clin Electrophysiol 1990;13(2):144-50  To investigate the electrophysiological significance of QRS alternans during narrow QRS tachycardia, transesophageal atrial pacing and recording was performed in 24 patients with a history of paroxysmal supraventricular tachycardia. Standard electrocardiograms showed ventricular preexcitation in 15 patients and normal QRS pattern in nine patients. The ventriculoatrial interval during tachycardia, as defined by means of transesophageal electrogram, allowed tentative diagnosis of the tachycardia mechanism. A 12-lead ECG was recorded either during spontaneous or induced tachycardia, as well as during transesophageal atrial pacing at increasing rates. Electrical alternans occurred spontaneously in eight patients (33%, group A): five with accessory pathway reentry (mean VA: 136 +/- 43 msec), and three with AV nodal reentry (mean VA: 48.3 +/- 12 msec). Tachycardia rate ranged between 170 and 230 beats/min (mean 200.7 +/- 16). In two patients, alternation of the QRS occurred only in the presence of a heart rate exceeding 180 and 190 beats/min, respectively. The amplitude of QRS remained stable during tachycardia in 16 patients (67%, group B): 14 had accessory pathway reentry (mean VA: 137.5 +/- 32 msec), and two had AV nodal reentry (mean VA: 45 +/- 7 msec). In this group, the tachycardia rate ranged from 150 to 210 beats/min (mean 175 +/- 12). Incremental transesophageal atrial pacing up to rates equal to that of tachycardia was performed in five patients from group A and in five patients from group B. Electrical alternans could not be induced in both groups with pacing at progressively increasing rates.

    Transesophageal pacing in the diagnosis of accelerated atrioventricular conduction. Patruno N, Pulignano G, Urbani P, Greco C, Critelli G. Cardiologia 34(1):87-91, 1989. The term "enhanced atrioventricular nodal conduction" (EAVN) is used to indicate an electrophysiologic condition characterized by subnormal conduction delay with reduced decremental properties in the AV node, which can be responsible for rapid ventricular rates in the event of fast atrial rhythms. Although identification of such an entity usually requires definition of the AV conduction intervals, some authors have suggested that EAVN can be diagnosed, by means of atrial pacing only, when 1:1  conduction with narrow QRS complexes occurs during atrial pacing at rate higher than 200 bpm. The use of incremental transesophageal atrial pacing (TAP) as a noninvasive tool for identification of EAVN was investigated in 19 patients. Fifteen had a history of supraventricular tachyarrhythmias (11 Wolff-Parkinson-White syndrome; 2 Lown-Ganong-Levine syndrome; 1 intranodal AV reentry tachycardia; 1 sick sinus syndrome); 4 patients exhibited an electrocardiographic pattern of preexcitation without a history of tachyarrhythmias. Analysis of AV conduction at fast induced rates was hampered in 5 patients because of the easy occurrence of reciprocating tachycardia and/or atrial fibrillation during TAP, as well as because of the persistence of delta wave at cycle lengths (CL) shorter than 300 ms. Among the remaining patients, in 7 (50%, Group A), 1:1 AV conduction was present at pacing CL shorter than 300 ms. In 7 patients (50%, Group B), AV block occurred at pacing CL longer than 300 ms. 

    Transesophageal pacing for prognostic evaluation of preexcitation syndrome and assessment of protective therapy. Critelli G, Grassi G, Perticone F, Coltorti F, Monda V, Condorelli M. Am J Cardiol 1983 Feb;51(3):513-8. An esophageal lead was used to perform decremental atrial pacing and elective induction of atrial fibrillation (AF) in 5 patients with the Wolff-Parkinson-White (W-P-W) syndrome before and after amiodarone therapy. In the control state, 1:1 atrioventricular (AV) conduction over the accessory pathway ranged from 220 to 260 ms (mean 232). The shortest R-R interval during AF ranged from 190 to 210 ms (mean 198). The ventricular rate ranged from 175 to 212 beats/min (mean 196). After amiodarone therapy, the shortest cycle length with 1:1 AV conduction increased in all patients, ranging from 290 to 540 ms (mean 370); during AF, no preexcited beat was present in 2 patients, whereas the minimal preexcited R-R interval in the remaining 3 was 290, 240, and 370 ms, respectively. The ventricular response during AF decreased in all patients. Thus, esophageal pacing is a useful method for identifying patients at risk with the W-P-W syndrome and for assessing appropriate management in individual patients. Amiodarone provides protection against life-threatening arrhythmias in these patients.

    Electropharmacological test with class-I C drugs in paroxysmal supraventricular re-entrant tachycardia: is a negative result with a drug predictive of the ineffectiveness of other drugs of the same class? Inama G, Furlanello F, Braito G, Guarnerio M, Vergara G. Divisione di Cardiologia, Ospedale S. Chiara, Trento. G Ital Cardiol 1991, 21(2):131-8. Propafenone and flecainide, both I C class drugs, are first choice in the treatment of paroxysmal supraventricular reciprocating tachycardia. The aim of this study was to check whether a negative or paradoxical electropharmacological test with one of the two drugs was predictive of an equally negative or paradoxical test with the other drug. Thirty patients with disabling paroxysmal supraventricular reciprocating tachycardia, 16 M, 14 F, mean age 30.6 +/- 16 years, were studied with serial electropharmacological tests using esophageal approach. The reentry circuit was sustained by an anomalous pathway in 25 patients (83.5%) whereas it was idionodal in the other 5 (16.5%). Propafenone was tested in 13 patients (43.5%, group A) after flecainide had resulted negative or paradoxical in the first test. In 17 patients (56.5%, group B) flecainide was tested after propafenone had resulted negative or paradoxical. The second drug tested was also ineffective in 14 of the 30 patients (group A + group B) while it had positive results in 16 patients. Specifically, propafenone was positive in 6 of the 13 patients (group A) in whom flecainide had been negative, and flecainide was positive in 10 of the 17 patients (group B) with acute negative or paradoxical propafenone test. These "acute" results were confirmed in steady-state with esophageal study and in the follow-up (21.9 +/- 9.3 months). Conclusions: 53.5% of the patients who are "non responders" to the electropharmacological test with one of the two drugs (propafenone or flecainide) may be "responders" to the other drug. Thus the ineffectiveness of one of the two drugs is not predictive of ineffectiveness of the other. 

    Electrophysiological evaluation of tachycardias using transesophageal pacing and recording. Volkmann H, Kuhnert H, Dannberg G. Friedrich Schiller University, Jena, East Germany. Pacing Clin Electrophysiol 1990, 13(12 Pt 2):2044-7. Programmed electrical stimulation of the heart to initiate and terminate tachycardia has been useful in the evaluation of supraventricular and ventricular tachyarrhythmias. A wide use of these procedures, however, failed because of the expense of the invasive approach as well as the lack of physician experience in smaller hospitals. These disadvantages of the invasive proceeding can be abolished by transesophageal pacing. In our study, supraventricular tachycardias were initiated by programmed transesophageal atrial stimulation in 251 patients (AV node reentry in 75 patients, orthodromic AV reciprocating tachycardia using accessory pathway in 97 patients, antidromic AV reciprocating tachycardia in 11 patients, and atrial reentry in 39 patients). The stimulation protocol included one and two extrastimuli during sinus rhythm and after a pacing drive at different cycle lengths. The electrophysiological mechanism of tachycardias was determined by surface ECG, VA interval (esophageal lead), initiation mode at programmed transesophageal stimulation and by behavior of AV conduction and refractoriness. In 29 patients the mechanism of tachycardia was not clear. Invasive electrophysiological study was done in 219 of these 251 patients. In only nine patients, the supposed mechanism of tachycardia was not confirmed by invasive investigation. In 11 patients, the electrophysiological mechanism remained uncertain. In conclusion, the noninvasive transesophageal pacing is an appropriate method for evaluation of supraventricular tachycardia. It allows serial drug testing in a simple manner for finding an effective antiarrhythmic treatment.

    Comparative study of the effects of verapamil, ethmozin and ethacizine on provoked attacks of atrioventricular nodal reciprocal tachycardia. Smetnev AS, Islam MN, Sokolov SF, Golitsyn SP, Bankuzov VA, Malakhov VI. Kardiologiia 1990 Feb;30(2):32-7. 27 patients underwent serial electrophysiological studies by using transesophageal atrial stimulation. A-V nodal reciprocal tachycardia was documented by intracardiac electrophysiological examinations. Sustained tachycardia was induced in all the patients before drug administration. On day 4 after oral verapamil, 320 mg/day, ethmosine, 800 mg/day, and ethacizine, 150 mg/day, the patients were subjected to transesophageal atrial stimulation. An antiarrhythmic effect was regarded to be reached if the authors failed to induced sustained tachycardias again. Verapamil, ethmosine, and ethacizine were found to be beneficial in 21 (78%), 13 (48%) and 21 (78%) patients, respectively. A comparative analysis demonstrated that ethacisine was not inferior to verapamil, but ethmosine produced less effects than verapamil and ethacizine. The crossover and individual efficacy shown by each drug suggests that it is necessary to use the technique of serial testing and to choose beneficial drugs from a possibly wide range of medicaments for each patient.

    An evaluation of transesophageal atrial pacing for studying the use-dependence effect of anti-arrhythmia drugs. Vernero A, Cuba J, Lazzari JO. Hospital Pirovano, Buenos Aires, Argentina. Medicina (B Aires) 1992;52(4):303-10. Use-dependent effect is characteristic of certain antiarrhythmic drugs, mainly those included in Group I of Vaughan-Williams classification. There is an increasing interest in the study of this phenomenon in order to correlate it with the potential arrhythmogenic effect of currently used antiarrhythmic drugs. Use-dependent effect produces widening of the QRS ECG complex as the heart rate is increased. Thus, to produce the necessary changes in heart rate to clinically disclose this phenomenon, endocardial stimulation of the right ventricle is usually done both in control condition and under the effect of the tested drug. As this is an invasive method, the amount of information collected on this important aspect of the antiarrhythmic drug effects has been limited. Hence, we decided to confirm whether transesophageal cardiac pacing is a suitable method to produce controlled changes of the heart rate in order to analyse the use-dependent phenomenon. In this study we included 14 patients, 9 women and 5 men aged 47.85 +/- 13.91 years and ejection fraction of 54.64 +/- 7.19%. Transesophageal stimulation was performed up to the Wenckebach point and the previous rate producing 1:1 A-V response was considered. ECG was recorded in an ink-jet three-channel electrocardiograph at 100 mm/sec chart speed and QRS duration was measured. All patients were studied in the basal unsedated state, free of any medication and after the administration of 3.13 +/- 0.74 mg/kg of flecainide during 4.07 +/- 1.4 days. Atrial capture was obtained with pulses of 15 mA and 18 msec. Heart rate attained before treatment was 150 +/- 21.83 bpm and 144.28 +/- 19.88 bpm under the effect of flecainide (p = NS).

    Electrophysiological evaluation of the sodium-channel blocker carbamazepine in healthy human subjects. Kenneback G, Bergfeldt L, Tomson T. Huddinge University Hospital, Sweden. Cardiovasc Drugs Ther 1995 Oct;9(5):709-14. Carbamazepine (CBZ) is a sodium-channel blocker used mainly for the treatment of epileptic seizures and neuralgias. It may impair the function of the cardiac conduction system in susceptible patients, but its electrophysiological effects have not been thoroughly assessed in the normal heart, which was the aim of the present study. Ten healthy volunteers, mean age 32 years, underwent two electrophysiological investigations at baseline and three at different dose levels of CBZ. The transesophageal atrial stimulation technique was used to evaluate sinus node function, refractoriness of the atrial myocardium, atrioventricular conduction, and ventricular depolarization and repolarization (as reflected by the QRS, JT, and QT intervals) at spontaneous rhythm and after atrial pacing. Atropine was administered to facilitate 1:1 conduction and assessment of rate-dependent effects. At the highest CBZ dose (800 mg/day), which gave plasma concentrations within the upper therapeutic range, the PQ interval was mildly prolonged (151 vs. 159 msec; p < 0.01). In addition, the shortening of the JT interval normally seen at higher pacing rates was counteracted by high-dose CBZ, as demonstrated by a lower mean slope of the regression line after atropine and CBZ than after atropine alone (0.17 vs. 0.20; p < 0.05). No other effects were detected. At therapeutic levels CBZ had minimal effects on the healthy conduction system, supporting its safe use in the absence of cardiac disease.

    Sotalol in the Wolff-Parkinson-White syndrome: an electrophysiological and clinical study. Inama G, Furlanello F, Vergara G, Guarnerio M, Braito G, Nassivera E. Divisione di Cardiologia, Ospedale S. Chiara, Trento. G Ital Cardiol 1992 Jun;22(6):701-13. Distinctly different from the other beta-blocking agents, sotalol prolongs action potential duration in myocardial and Purkinje fibers, and increases atrial as well as ventricular effective refractory periods. Similarly, antegrade and retrograde accessory pathway refractory periods are increased by sotalol. The electrophysiologic and clinical effects of sotalol were studied in 40 patients (31 male and 9 female, mean age 32 +/- 14 years) with Wolff-Parkinson-White Syndrome (WPW). All patients had disabling episodes of supraventricular tachyarrhythmias (ST). Of the 40 patients, 15 (37%) had spontaneous recurrence of paroxysmal supraventricular reciprocating tachycardia (PSRT), 14 (35%) of atrial fibrillation (AF) and 11 (28%) of both PSRT and AF. All of the patients were non responders to serial transesophageal electropharmacological tests using I C class drugs. Sotalol 252 +/- 73 mg daily was administered, and, in steady-state, a new transesophageal study (TS) was performed to observe the re-induction of PSRT and/or AF. 34 patients (85%) were responders to TS (noninducibility of ST, or nonsustained ST or AF inducibility with an increase of 30% in the minimum R-R interval between pre-excitated beats during AF) and the results were confirmed during a follow-up of 17 +/- 9 months. In the non-responder group (5 patients), a I C class drug was associated with sotalol. One patient, who was a "non responder" to sotalol, sotalol + I C class drug, and to amiodarone, underwent surgical therapy. In the 26 patients (65%) who had episodes of PSRT (37%) or episodes of PSRT and AF (28%), it was impossible to reinduce PSRT in 85% of the cases. AF was induced at baseline in all of the studied patients, but after sotalol administration in 15 patients, it was impossible to reinduce AF. The rate of induced AF decreased from 208 +/- 39 beats/min to 156 +/- 36 beats/min (p < 0.001). The mean shortest R-R interval between pre-excitated beats increased from 214 +/- 35 (baseline) to 293 +/- 97 msec (sotalol steady state) (p < 0.001). No side effects were observed. A significant prolongation (p < 0.001) of the QTc interval was observed in all the patients after sotalol administration (from 0.39 +/- 0.2 to 0.42 +/- 0.02 sec.). On the basis of our results, we may conclude that sotalol has a potent effect on the antegrade refractoriness of the anomalous pathway and, in WPW syndrome at risk, is also effective in patients who don't respond to I C class drugs.

    The value of transesophageal atrial pacing in predicting the efficacy of antiarrhythmic drugs in patients with paroxysmal narrow QRS complex tachycardia. Kulakowski P, Dluzniewski M, O'Nunain S, Camm AJ, Wardzynska M,Ceremijzynski L (Grochowski Hospital. Warsaw and St. George's Hospital Medical School. London. Pacing Clin Electrophysiol 1992 Jun;15(6):895-904. Transesophogeal atrial pacing (TAP) is used in the diagnosis and treatment of paroxysmal narrow QRS complex tachycardia (NQT). The aim this study was to assess the value of this technique in predicting the efficacy of antiarrhythmic therapy. The study group consisted of 30 consecutive patients with spontaneous NQT whose clinical tachycardia was inducible by TAP. Baseline TAP was performed off all antiarrhythmic medication and repeated during oral antiarrhythmic drug therapy. The pacing protocol consisted three stages: a single extrastimulus introduced at progressively shorter coupling intervals during sinus rhythm, pacing at incremental rates to the point of second-degree AV block, and bursts of rapid pacing. On repeat stimulation while on oral antiarrhythmic therapy (37 pacing studies) NQT was still inducible in 12 cases. During the follow-up period ten patients developed a recurrence of NQT: nine cases out of 12 (75%), in whom NQT was inducible while on antiarrhythmic therapy, and one case out of 25 (4%), in whom NQT was not inducible (P < 0.001). The sensitivity of TAP in predicting the outcome of the patients with NQT was 90% and the specificity 89%. The negative predictive value of TAP (prediction of no recurrence of NQT) was 96%, and the positive predictive value (prediction of recurrence of NQT) was 75%. We conclude that TAP is a simple and accurate method for predicting the efficacy of antiarrhythmic treatment in patients with NQT. 

    Phase image analysis in Wolff-Parkinson-White syndrome. Role of transesophageal pacing. Santinelli V, Fazio S, Turco P, De Paola M, Santomauro M, Chiariello M. University of Naples, Italy. Acta Cardiol 1991;46(1):43-50 Phase image analysis (first Fourier harmonic transformation) has been performed in 5 men with WPW syndrome to define the abnormal patterns of ventricular emptying during sinus rhythm and transesophageal pacing at different rates. All patients but one showed basal ventricular preexcitation. Of the 4 patients with basal ventricular preexcitation the earliest ventricular emptying occurred in the left ventricular free-wall in 1 patient and in the right ventricular free-wall in 3 patients. In the patient without ventricular preexcitation at rest transesophageal pacing at a rate of 100 bpm induced first ventricular activation in the left lateral ventricular free-wall while at a rate of 120 bpm it returned to normal. In the patients with ventricular preexcitation at rest, the basal image abnormalities become more evident as preexcitation was augmented. Of interest, in 1 patient with basal type B ventricular preexcitation the sequential phase image analysis, at a rate of 100 bpm confirmed the earliest ventricular activation in the right ventricular free-wall while at a rate of 120 bpm showed the earliest emptying in left ventricular free-wall suggesting the presence of 2 accessory connections. We conclude that phase mapping combined with transesophageal pacing may be a useful and reliable method to localize single as well as multiple accessory pathways in patients with ventricular preexcitation.

    Reproducibility of transesophageal pacing in patients with Wolff-Parkinson-White syndrome. Fenici R, Ruggieri MP, di Lillo M, Fenici P. Catholic University of Rome, Italy. Pacing Clin Electrophysiol 1996 Nov;19(11 Pt 2):1951-7  The purpose of this study was to assess, in patients with ventricular preexcitation, the time dependent physiological variation of antegrade conduction properties in the AV node and in accessory pathways (Aps) as a function of autonomic tone variation induced by posture and physical effort, using noninvasive transesophageal atrial pacing. In 74 WPW patients (mean age 21.31 +/- 9.46 yrs), AV node and Kent antegrade effective refractory periods (at pacing cycle lengths 600, 400, and 320 ms), Wenckebach point, shortest preexcited RR intervals during sustained atrial fibrillation (AF) or atrial pacing, as well as the inducibility of AV reentry tachycardia (AVRT) and AF/flutter (AFL) were assessed. All measurements were carried out at rest, in supine and upright positions, and during effort. A second study was carried out approximately 3 months after the first study. The coefficient of variation (CVs) and reproducibility (CRs) were calculated. For each parameter, the differences between the mean of the two studies were not statistically significant. The CVs and CRs ranged between 0.4% and 4% and between 2 and 28 ms, respectively. AF was induced in 40 (54%) of 74 patients at the first study and in 30 (40.5%) of 74 patients at the second study. AVRT was induced in 33 (45%) of 74 patients at the first study and in 38 (51.3%) of 74 patients at the second study. The reproducibility was 45% for AF/AFL and 65% for reentry tachycardia. Transesophageal atrial pacing is a reliable method for noninvasive reproducible evaluation of antegrade electrophysiological properties of both the AV node and APs in WPW patients. However, the effect of autonomic balance variation has to be taken into account and precisely defined because it may significantly affect the inducibility of supraventricular arrhythmias and the estimation of the absolute values of the vulnerable parameters.

    Factors affecting the vulnerability of the left atrium during rapid transesophageal atrial stimulation. Stancak B, Misikova S, Schroner Z, Pella J. Kosice. Vnitr Lek 1994 Jan;40(1):3-8. Atrial fibrillation (AF) is associated with a higher morbidity and mortality because of the risk of systemic or pulmonary embolism as well as the negative impact on cardiac function. The authors investigate in the submitted paper factors influencing the vulnerability of atria during transoesophageal atrial stimulation (TESP). The group comprised 68 patients with a sinus rhythm, mean age 56.9 +/- 17.9 years. Depending on the response to rapid atrial stimulation, the patients were divided into three groups. In group I (small disposition to AF) they revealed a significantly lower age, the relative thickness of the left ventricular wall assessed by echocardiography and the dimension of the left atrium, as compared with groups with a medium increased (II) and high disposition (III) for AF. In group III hypertonic changes on the fundus were found more frequently, as well as anamnestic data on hypertension, diabetes and pathological values of the recovery period of the sinoatrial node. At the same time significantly lower values of the rate of the E wave were observed and of the ratio of amplitudes and E/A integrals from the Doppler record of the mitral valve. The weight of the left ventricle and its index by groups increased, however the changes did not attain statistical significance. Indicators of left ventricular systolic function did not differ. The authors conclude that the main independent factors which determine the response to provoked AF by the TESP method are the diastolic left ventricular function documented by the Doppler method, the diameter of the left atrium, the automation of the SA node. Less important factors are left ventricular hypertrophy and age.

    Atrial disorders of the heart rhythm in hypertension.Nikulin IA, Iurenev AP, Fofanova TV. Kardiologiia 1993;33(6):62-4. A total of 57 males with stage-II hypertensive disease were studied to diagnose latent atrial disturbances of cardiac rhythm. Holter monitoring showed that latent atrial arrhythmias were diagnosed in 82.4% of patients. There was a significant correlation between the incidence of atrial arrhythmias and the left atrial dimension defined at echocardiography. A dilatation of the left atrium of greater than 4.0 cm serves a factor that predisposes to frequent atrial extrasystoles and atrial tachycardias. The electrical instability of a dilated left atrium was evidenced by diagnostic transesophageal cardiac pacing which readily induced persistent paroxysms of atrial fibrillations in patients with enlarged left atrium. The simultaneous use of Holter monitoring and diagnostic transesophageal cardiac pacing in the outpatient setting enhances their diagnostic value in detecting latent atrial arrhythmias in patients with hypertensive disease.

    Comparison of anti-arrhythmic therapy guided by the transesophageal electropharmacologic test and emperic therapy in the prophylaxis of atrial fibrillation recurrence. Fera MS, Carunchio A, Burattini M, Mazza A, Coletta C, Galati A, Ceci V. Ospedale S. Spirito, Roma. G Ital Cardiol 1997 Feb;27(2):152-63. BACKGROUND: There is no written data about the efficacy of transesophageal electropharmacologic test (TEPT) to guide antiarrhythmic therapy in the prophylaxis of paroxysmal atrial fibrillation (PAF) recurrences. Aim of this study was to assess the efficacy of TEPT compared to empiric treatment in the prophylaxis of PAF. METHODS: One-hundred-sixty patients (pts) with previous episodes of PAF were randomized in two groups: Gr A (90 pts) was submitted to basal transesophageal electrophysiologic study (BTES); Gr B (70 pts) was submitted to randomized empiric antiarrhythmic therapy with flecainide (F), propafenone (P) and sotalol (S). The end-points of stimulation protocol in Gr A were the induction of sustained atrial fibrillation (SAF)- > or = 1 min duration- or the end of protocol. SAF was inducible in 68/90 pts (Gr A1) while it was not in 22/90 pts (Gr A2). Pts in Gr A1 were subsequently submitted to TEPT at steady-state of F, P or S randomized in first choice. Pts responders (R) (SAF non inducible) were submitted to TEPT with other antiarrhythmic drugs randomized in second choice: R were followed-up with the same drug in chronic oral assumption, while non responders (NR) were submitted to TEPT with the last drug and followed-up with the same drug both in R and NR case. The same stimulation protocol was employed in TEPT as in BTES. Pts in Gr A2 withdrew from the study. During follow-up all-pts were submitted to periodic specialist examinations every three months. In case of PAF recurrence pts withdrew from the study. RESULTS: Mean follow-up duration in the study population was 17.5 +/- 8.5 months. One-hundred-eight TEPT were performed in Gr A1: 36 tests with F, 40 with P and 32 with S. Twenty pts were R with F (55% of tests) and 17 finished the follow-up, 22 pts were R with P (55% of tests) and 16 finished the follow-up, 19 pts were R with S (59% of tests) and 15 finished the follow-up; 3 pts with F, 2 pts with P and 2 pts with S were NR in last choice and finished the follow-up. In Gr A1 61/68 pts (90%) were R and 55/68 (81%) finished the follow-up (13 pts withdrew from the study). In Gr B (70 pts) 23 pts were randomized to F and 20 finished the follow-up, 24 pts were randomized to P and 20 finished the follow-up, 23 pts were randomized to S and 20 finished the follow-up (10 pts withdrew from the study). PAF recurrences during follow-up in Gr A1 were in 15/55 pts (27%): 9/48 pts (19%) R and 6/7 pts (86%) NR, and in Gr B in 41/60 pts (68%). Gr A1 vs Gr B p < 0.001. Univariate and multivariate statistical analysis showed the empiric treatment as the only variable with high predictive value for PAF recurrences (risk ratio 1.53). PPV and NPV of TEPT were respectively 86 and 81%. CONCLUSIONS: TEPT-guided antiarrhythmic therapy in the prophylaxis of PAF recurrences seems to be an effective method in predicting the efficacy of the chronic antiarrhythmic therapy, when compared to the empiric treatment. The non inducibility of SAF at TEPT would have a high predictive value for event-free follow-up.

    Usefulness of invasive and non-invasive electrophysiologic studies in the selection of antiarrhythmic drugs for the patients with paroxysmal supraventricular tachyarrhythmia. Satake S, Hiejima K, Moroi Y, Hirao K, Kubo I, Suzuki F, Suzuki F. Jpn Circ J 1985 Mar;49(3):345-50. A comparison of the effects of several antiarrhythmic agents was made in a study of 70 patients - 15 with manifest Wolff-Parkinson-White (WPW) syndrome, 17 with concealed WPW syndrome, 18 with AV nodal re-entrant tachycardia, 14 with paroxysmal atrial fibrillation and 6 with paroxysmal atrial flutter - employing intracardiac stimulation and esophageal pacing. For the termination of paroxysmal supraventricular tachycardia, intravenous administration of verapamil or aprindine was more effective than that of disopyramide or procainamide. In AV nodal re-entrant tachycardia, verapamil was the most effective for termination. In the manifest WPW syndrome, disopyramide or aprindine was indicated especially for patients with the accessory pathways of the short antegrade refractory period, because these drugs lengthened the refractory period of the accessory pathways. For the purpose of converting atrial fibrillation or flutter to the sinus rhythm, type IA drugs such as disopyramide were indicated. However, verapamil was effective for slowing down the ventricular rate in atrial fibrillation or flutter except in cases of manifest WPW syndrome. A 6-month follow-up study showed that oral administration of verapamil was also useful for putting a stop to the attacks in 24 out of 32 patients with paroxysmal supraventricular tachycardia, while oral disopyramide prevented the recurrence of atrial fibrillation in only 4 of 10 patients.

    Role of transesophageal pacing in recurrent atrial fibrillation. Experience with propafenone. Turco P, Guarino P, Parente A, Viola V, Candelmo F, Bellizzi G, Foffa A, Morella A, Martino DF. Electrophysiology Laboratory, Ospedale Civile Ariano-AV, Irpino-AV, Italy. Angiology 1994 Feb;45(2):95-100. To assess the role of transesophageal pacing (TP) at very high rates in the follow-up of patients with recurrent and sustained paroxysmal atrial fibrillation (AF) on therapy, the authors studied 15 patients (10 women, 5 men; aged forty-four to seventy-seven years old). Of them only 1 had a mild mitral regurgitation; none had hyperthyroidism or acute ischemic heart disease. They tested propafenone (P) at a dose of 1.4-2 mg/kg over ten minutes as an intravenous bolus and 0.5 mg/minute as intravenous maintenance for two hours and then 300 mg twice daily orally and chronically. Serial TPs at very rapid rates (up to 600 bpm) were performed to test the long-term efficacy of P to prevent paroxysmal AF. The mean follow-up was fifteen months (nine to twenty-four months). RESULTS: Intravenous P converted AF in five to ninety minutes (mean twenty-one minutes) in 9/15 patients (conversion rate of 60%); in an additional 4 patients oral P converted AF in two to fifteen hours. In the other 2 patients P failed to convert AF. Three patients experienced recurrence of AF in the early follow-up. Of the 10 patients who completed the entire protocol, only 1, who had mild mitral prolapse regurgitation and AF induction by TP, experienced new episodes of AF during follow-up. No significant side effects were noted during P therapy. CONCLUSIONS: Propafenone appears safe and effective for controlling and preventing recurrent and sustained AF. Transesophageal pacing is a valid tool for predicting the efficacy of long-term therapy in the follow-up of patients with paroxysmal atrial fibrillation.

    Propafenone in Wolff-Parkinson-White syndrome at risk. Santinelli V, Turco P, De Paola M, Smimmo D, Giasi M, Santinelli C, Chiariello M, Condorelli M. University of Naples, Italy. Cardiovasc Drugs Ther 1990 Jun;4(3):681-5. We present our experience on the efficacy of propafenone in ten symptomatic patients with Wolff-Parkinson-White syndrome. The symptoms were dizziness in seven patients and syncope in three patients. While experiencing the symptoms, three of them presented an episode of atrial fibrillation, the shortest preexcited RR intervals being 140, 190, and 200 ms. In the other seven patients, the ECG was not recorded during the symptoms, but an episode of atrial fibrillation was subsequently induced by transesophageal pacing. The shortest preexcited RR intervals during induced atrial fibrillation were 180, 200, 270, 240, 230, 250, and 200 ms. Seven patients had both atrial fibrillation and supraventricular tachycardia. Propafenone (1-2 mg/kg) administered IV in only the patients with sustained atrial fibrillation (spontaneous in two and induced in one patient) prolonged the shortest preexcited RR intervals from 190, 200, and 180 ms to 340, 335, and 340 ms. In the other seven patients, propafenone was not given IV because atrial fibrillation rapidly deteriorated into ventricular fibrillation (one patient) or spontaneously reverted within 1-2 minutes to sinus rhythm (six patients). After oral propafenone, serial trans-esophageal pacing studies reinduced atrial fibrillation in 4 of 6 patients (the shortest preexcited RR intervals increased from 190, 180, 200, and 270 ms to 420, 320, 340, and 380 ms); only in one patient was it possible after propafenone to induce an atrial flutter without preexcitation. After propafenone therapy in 4 of 7 patients, supraventricular tachycardia was not inducible.

    Evaluation of the clinical acute electrophysiological effects of propafenone using transesophageal atrial pacing. He F, Zhao X, Cheng X. Shanxi Medical College, Taiyuan. Chung Kuo I Hsueh Ko Hsueh Yuan Hsueh Pao 1994 Jun;16(3):239-41. The clinical acute electrophysiological effects of propafenone were evaluated using transesophageal atrial pacing (TEAP) in 65 patients with various arrhythmias. The mean age of the patients was 41 years. Incremental pacing and programmed ectopic stimulation were performed on each patient before and during drug administration. Propafenone was given as a bolus injection of 1.5mg.kg-1 body weight followed by drip infusion at a rate of 1 mg.min-1. S-R, P wave, P-R and QRS intervals were prolonged from 194.43 +/- 21.59, 97.49 +/- 10.92, 148.00 +/- 16.20 and 82.21 +/- 7.18ms 223.00 +/- 29.25, 100.22 +/- 10.60, 166.60 +/- 20.10 and 86.54 +/- 7.19ms, respectively (P < 0.005), A-V conduction system effective refractory period (AVCSERP) was prolonged from 316.35 +/- 82.97ms to 360.31 +/- 82.67ms (P < 0.0001) in the treated group. There was no change of atrial ERP and QTc interval (P > 0.05). Fast and slow pathway ERP was prolonged by 13% and 28% of the control value, respectively (P < 0.015), and accessory pathway ERP was prolonged from 278.89 +/- 27.13ms to 305.56 +/- 33.58ms (P < 0.001), in the treated group. Sinus cycle length, corrected sinus nodal recovery time and total sinus-atrial conductive time were significantly prolonged (P < 0.0001). The results can partially explain the antiarrhythmic effects and the side effects of propafenone. TEAP is dependable in evaluating the clinical electrophysiological effects of drugs.

    Paroxysmal supraventricular tachycardia: experience with propafenone. Santinelli V, De Paola M, Turco P, Smimmo D, Chiariello M. University of Naples, Italy. Angiology 1989 Jun;40(6):563-8. The authors studied the efficacy of intravenous (IV) (1.5-2 mg/kg) and oral propafenone (450 to 900 mg/day) in 16 patients with paroxysmal, sustained, recurrent supraventricular tachycardia (SVT). In 5 patients IV propafenone was not given, because of intolerant SVT. Nine patients had Wolff-Parkinson-White syndrome. IV propafenone immediately stopped and prevented reinduction of SVT in 9/11 patients. Oral propafenone prevented SVT induction in 3 of 5 patients. In the 9 patients responsive to IV propafenone, oral propafenone was effective: in particular, in 6 patients SVT tachycardia was not induced by serial transesophageal pacings, and in the remaining 3 patients the arrhythmia was still induced but was slower and of brief duration (3-5 seconds). In 11/12 patients responsive to oral propafenone the minimum effective dosage in preventing the induction of the arrhythmia was 600 mg/day. In only 1 patient was the dose of 450 mg/day equally effective. Propafenone administration was not associated with major side effects. In conclusion, propafenone is very effective in the control of paroxysmal supraventricular tachycardia; intravenous propafenone can predict the efficacy of oral therapy.

    Effects of propofol on the human heart electrical system: a transesophageal pacing electrophysiologic study. Romano R, Ciccaglioni A, Fattorini F, Quaglione R, Favaro R, Arcioni R, Conti G, Gasparetto A. University La Sapienza, Rome Acta Anaesthesiol Scand 1994; 38(1):30-2. Previous studies have shown that infusion of propofol has sometimes been associated with bradyarrhythmias. To evaluate the effects of propofol on the electrical system of the heart, we carried out an electrophysiologic study with transesophageal pacing on ten healthy subjects scheduled for minor elective maxillo-facial surgery. By means of atrial pacing conducted by a progressive increase in stimulation cycles, we determined, in awake patients and during propofol anesthesia (2.5 mg kg-1 for induction, followed by 100 micrograms kg-1 min-1 for maintenance), the correct sinus recovery time and the eventual appearance of Wenckebach atrio-ventricular block. We did not notice sinoatrial node depression or pathologic increase in the atrio-ventricular conduction.

    Combination therapy with aprindine and verapamil for paroxysmal supraventricular tachycardia as assessed by transesophageal atrial pacing. Hirao K, Okishige K, Suzuki F, Hiejima K. Tokyo Medical and Dental University. Cardiovasc Drugs Ther 1991 Aug;5 Suppl 4:819-25. To assess the efficacy of combination therapy of aprindine (40 mg/day) and verapamil (160 mg/day), transesophageal programmed atrial stimulation was performed on 21 patients with paroxysmal supraventricular tachycardia (including 12 patients with atrioventricular nodal reentrant tachycardia and nine patients with atrioventricular reentrant tachycardia) under four conditions: a) control, b) aprindine alone, c) verapamil alone, and d) aprindine + verapamil. Results: a) Aprindine, verapamil, and aprindine + verapamil prevented paroxysmal supraventricular tachycardia induction in 2/21, 3/21, and 9/21 patients, respectively; b) aprindine + verapamil prolonged the cycle length of paroxysmal supraventricular tachycardia more than aprindine or verapamil alone; c) aprindine, verapamil, and aprindine + verapamil decreased the AV blocking rate by 15, 23, and 35 beats/min, respectively, in comparison with the control state; d) aprindine, verapamil, and aprindine + verapamil prolonged the effective refractory period of atrioventricular conduction system by 20, 34, and 76 msec, respectively, compared with the control state. In conclusion, aprindine + verapamil appear to be more effective than aprindine or verapamil alone in preventing paroxysmal supraventricular tachycardia with nodal reentry, but there was less benefit in those without nodal reentry (Wolff-Parkinson-White group).

    Use of digoxin in patients with paroxysmal supraventricular tachycardia. Smetnev AS, Titov VN, Shevchenko NM, Gurevich EM. Kardiologiia 1989 Apr;29(4):61-4. The effectiveness and electrophysiologic mechanisms of antiarrhythmic effect of digoxin were examined in 27 patients with paroxysmal atrioventricular nodal reciprocal tachycardia (PAVNRT) and supraventricular tachycardia (SVT) due to latent complementary conductive pathways, i. e. latent Wolff-Parkinson-White (WPW) syndrome. To assess antiarrhythmic action of digoxin, transesophageal pacing and plasma digoxin radioimmonoassays were used. Preventive antiarrhythmic efficiency of digoxin was 53% in PAVNRT patients, and 25% in SVT patients with latent WPW syndrome. Antegrade atrioventricular conduction block seems to be the mechanism of oral digoxin preventive effect. There was no relationship between antiarrhythmic efficiency of digoxin and its plasma level.

    Reversible protective effect of propafenone or flecainide during atrial fibrillation in patients with an accessory atrioventricular connection. Auricchio A. Department of Cardiac Surgery, University of Rome, Tor Vergata, European Hospital, Italy. Am Heart J 1992 Oct;124(4):932-7. In 34 patients with a symptomatic accessory atrioventricular connection the reversible protective effect of orally administered flecainide (300 mg/day) and of propafenone (900 mg/day) in control of ventricular response during atrial fibrillation by exercise was assessed. The study consisted of three sections of 1 week each: an initial treatment phase during which propafenone or flecainide was administered, a drug-free phase, and a period of crossover to treatment with the other drug. At the end of each phase, transesophageal stimulation was performed during physical exercise to induce atrial fibrillation episodes: the goal was to control the persistence of drug effectiveness. At rest, the mean and shortest R-R interval during the period of induced atrial fibrillation in patients who were treated with flecainide or propafenone increased significantly as compared with the drug-free period. On the other hand, at maximum exercise levels no difference in both shortest and mean R-R intervals during atrial fibrillation was observed between patients who were treated with flecainide and those who were treated with propafenone, as well as between flecainide treatment and the drug-free period, whereas a slightly significant difference persisted with propafenone treatment (p < 0.05). In addition, at maximum exercise levels no significant difference in the number of preexcited QRS complexes among the three treatments was noted. The data from this study suggests that a reversible protective effect against rapid ventricular rate as the result of an episode of atrial fibrillation exists during exercise in patients with a symptomatic accessory atrioventricular connection who are treated with flecainide or propafenone.

    Partial reversal by exercise of protective effect in atrial fibrillation inducibility in patients with an accessory atrioventricular connection: comparison between flecainide and propafenone. Auricchio A, Auricchio U, Chiariello L. Universita di Roma Tor Vergata. G Ital Cardiol 1994 Feb;24(2):131-6. We have prospectively evaluated the reversibility of the protective effect of propafenone (P) and flecainide (F) on atrial fibrillation (AFib) inducibility in 31 patients with a symptomatic accessory atrioventricular connection during exercise. Each patient underwent repeated transesophageal stimulation and exercise testing after a drug-free week, or after a week of P (900 mg/daily), or F (300 mg/daily) given orally. The end point of the transesophageal stimulation was the induction of AFib. Because no AFib could be induced both at rest and at peak exercise, P or F was considered effective in 5 patients (16%) and 4 patients (13%), respectively. In contrast, drug therapy with P was totally ineffective in 10 patients (32%), while F was completely unable to control AFib induction in 14 patients (45%). A partial efficacy of antiarrhythmic drug therapy, in terms of AFib inducibility only at peak exercise, was achieved in 16 patients (52%) treated with P, and in 13 patients (40%) with F. The comparison of the mean R-R intervals during AFib between patients considered partial responders to drug therapy (AFib inducibility only at peak exercise) and those who completely failed any drug therapy did not show significant differences both at rest or during exercise. No correlation in the plasma concentration of P or F and AFib inducibility or duration was found. Thus, the data of this study shows that the reversible protective effect of IC antiarrhythmic class drugs by exercise seems related to inappropriate control on the substrate for AFib inducibility, and there exists a partially discrepant antiarrhythmic effect between the heart rate control during AFib and the inducibility of AFib.

    Opposite effects of propafenone and flecainide in a patient with reciprocating supraventricular tachycardia. Montenero AS, Natale A, di Bona G, Calvi V, Santarelli P, Manzoli U. Universita Cattolica del Sacro Cuore, Roma. Cardiologia 1990 Mar;35(3):253-6  A 46 year-old woman with Wolff-Parkinson-White syndrome (postero-septal accessory pathway), symptomatic for recurrent episodes of nonsustained paroxismal supraventricular tachycardia (PSVT), was empirically treated with propafenone (600 mg/day). After a week of therapy the patient returned to the hospital after an episode of syncope. She referred a significant increase in duration and frequency of "palpitations". Under treatment with propafenone a sustained PSVT could be induced during transesophageal testing. During the electrophysiologic study performed off drugs, only a nonsustained PSVT could be induced. After flecainide infusion (1 mg/kg) anterograde block of the accessory pathway was observed and only few beats (less than 8) of PSVT could be induced. The patient was discharged on flecainide (200 mg/day) and 1 month later a transesophageal testing was repeated showing an anterograde block of the accessory pathway at a pacing cycle length of 500 ms; no arrhythmias were induced. The patient has been asymptomatic on chronic oral therapy with flecainide during a follow-up period of 8 months. This case shows that 2 1c class antiarrhythmic drugs may have opposite effects (proarrhythmic and antiarrhythmic). Failure, or even the proarrhythmic effect of one drug, does not necessarily exclude the efficacy of another drug of the same subclass in preventing recurrence of PSVT.

    Evaluation of the effectiveness of corinfar in patients with ischemic heart disease using a method of repeated transesophageal electric stimulation of the left atrium. Mironova IIu, Sidorenko BA, Liakishev AA, Guliev AB. Kardiologiia 1989 Mar;29(3):34-7  The efficiency of 20 mg corinfar, administered sublingually, was assessed by means of esophageal left-atrial electrostimulation (EES) in 49 coronary patients with angina of functional classes 1 through 4. The antiischemic effect of corinfar was evaluated within 30 min after the administration in 27 patients and within 1 hour after the administration in 22 patients. To assess the reproducibility of the results, repeated EES was performed in 11 patients, treated with placebo this time. Corinfar was shown to have a good antiischemic effect 1 hour after sublingual administration, with the maximum induced heart rate rising from 130 to 147 beats per minute and the total duration of the stimulation increasing from 232 to 308 seconds. It is demonstrated that paired EES may be used for the assessment of corinfar efficiency in coronary patients.

    Effects of almokalant, a class III antiarrhythmic agent, on supraventricular, reentrant tachycardias. Almokalant Paroxysmal Supraventricular Tachycardia Study Group. Darpo B, Edvardsson N. Karolinska Hospital, Stockholm. Cardiovasc Drugs Ther 1997 Jul;11(3):499-508. The aim of the present study was to investigate the effects of almokalant on sustained reentrant supraventricular tachycardias. Reentrant tachycardias were induced, using transesophageal atrial stimulation, in 82 patients with atrioventricular reentrant tachycardia (n = 54) or AV nodal reentrant tachycardia (n = 28). After a baseline procedure during which the tachycardia was induced and overdrive terminated, the tachycardia was reinduced and studied during 12 minutes of infusion of either placebo or almokalant, aiming at plasma concentrations of 20, 50, 100, and 150 nmol/l. Each patient was studied at two dose levels during the same procedure. There was an increase in the RR interval during tachycardia of 6% at 100 nmol/l (p = 0.001 vs. baseline tachycardia). The QT interval during tachycardia increased by 5% (p = 0.001) at 50 nmol/l and by 10% (p = 0.001) at 100 nmol/l. Bundle branch block during tachycardia developed in 13% during almokalant infusion, aiming at 20 nmol/l, in 25% at 50 nmol/l, in 50% at 100 nmol/l, and in 33% at 150 nmol/l. Rapid baseline tachycardia, increasing almokalant dose, and an increasing number of induced tachycardias correlated with the appearance of bundle branch block. In six patients with AV nodal reentrant tachycardia, 2:1 AV block occurred, in all cases preceded by bundle branch block. The QT prolongation during sustained tachycardia was larger in patients who were noninducible at the same plasma concentration level than in the inducible patients. Almokalant caused bundle branch block and 2:1 AV block during sustained supraventricular tachycardia. These findings emphasize the importance of studying drug effects at rates in the range of clinical tachycardias that expose the conduction system to the limits of its refractoriness.

    Torsades de pointes induced by transesophageal atrial stimulation after administration of almokalant. Darpo B, Allared M, Edvardsson N. Karolinska, Stockholm. Int J Cardiol 1996;53:311-3. This case-report describes a patient who developed a torsades de pointes tachycardia after infusion of almokalant, a selective class III antiarrhythmic agent. The patient was studied with transesophageal atrial stimulation because of Wolff-Parkinson-White syndrome. After a base-line procedure during which an orthodromic tachycardia was induced and pace-terminated, almokalant was given intravenously. The corrected QT interval was markedly prolonged despite similar plasma concentration compared to the rest of the studied patients. During the continued pacing protocol several episodes of non-sustained ventricular tachycardia was observed after pacing induced pauses. A sustained orthodromic tachycardia with left bundle branch morphology was induced, and another almokalant infusion was given. At a plasma concentration of approximately 252 nmol/l the corrected QT interval was further prolonged to 680 ms and the patient developed a torsades de pointes tachycardia after a pacing induced pause. The tachycardia degenerated into ventricular fibrillation that required immediate defibrillation. One week later the patient underwent ablation of the accessory pathway. The QT interval was in the absence of preexcitation normal, and programmed electrical stimulation did not reveal any ventricular arrhythmias. Further studies will have to be performed to clarify whether an early and marked QT interval prolongation, such as observed in this patient, will be useful in identifying patients prone for proarrhythmias in relation to therapy with selective class III drugs.

    Use of transesophageal electrical stimulation of the left atrium for assessing the anti-ischemic effect of nitrosorbide. Mironova IIu, Liakishev AA, Kozlov SG, Sidorenko BA. Kardiologiia 1986 Nov;26(11):47-51. Anti-ischemic effect of sorbide nitrate was assessed by means of esophageal left-atrial electric stimulation in 26 coronary patients. This method is shown to be useful for objective assessment of the efficiency of antianginal drugs by acute tests in coronary patients. Repeated stimulation in the presence of sorbide nitrate treatment showed smaller ischemic ECG changes.

    Incidence of disorders of heart rhythm and conduction in idiopathic mitral valve prolapse. Mokrievich EA, Iurenev AP, Nikulin IA. Kardiologiia 1990 Sep;30(9):35-37. Out of 99 examinees, 78 patients had mitral valve prolapse of various degree. The control group included 21 individuals without the prolapse who had the same clinical signs. All the patients underwent Holter monitoring and bicycle ergometry; diagnostic transesophageal atrial pacing was performed in 26 examinees. Rhythm and conduction disturbances were shown to occur as frequently in patients with mitral valve prolapse as in the controls. For diagnosing extrasystolic arrhythmias, it was recommended to apply Holter monitoring to detect paroxysmal supraventricular tachyarrhythmias and to employ transesophageal cardiac pacing to find accessory pathways.

    Evaluation of cardiac risk in patients undergoing major vascular surgery. Usefulness and limitations of transesophageal atrial pacing. Romano M, Dei Poli M, Spinelli A, Catanzaro MT, Rusconi MG, Zorzoli C, Tacconi A, Marchetti L, Allaria B, Rota Baldini M. Ospedale Santa Corona, Garbagnate Milanese, Milano. Cardiologia 1994;39(10):713-9. Patients undergoing vascular surgery are at high risk of developing cardiac events in the perioperative period. The aim of the study was the evaluation of the predictive accuracy of transesophageal atrial pacing (TAP) in identifying patients at higher risk of developing major cardiac events (cardiac death, acute myocardial infarction, unstable angina, heart failure and sustained ventricular tachyarrhythmias). We studied 96 consecutive patients, 80 males and 16 females, median age 63, requiring arterial surgery (aortofemoral or aortoiliac bypass and thromboendoarterectomy, abdominal aneurysm resection and extracranial carotid thromboendoaterectomy). TAP was performed without cardioactive drugs in all patients, but one. After surgery CK and CKMB serial assessment and ECG recording were performed daily until the seventh postoperative day. Preoperatively all patients were admitted to the Intensive Care Unit and submitted to haemodynamic monitoring with Swan-Ganz catheter at least for 72 hours. Three patients did not undergo surgery because of severe ST depression during TAP. Thus, 93 patients (96.8% of the series) were the subject of this report. In the postoperative period only two events (2.1% of the patients) were recorded, one relapsing acute myocardial infarction and one ventricular fibrillation, both in patients with negative TAP. No death occurred. Our study shows a very low prevalence of major cardiac events.

    Usefulness of transesophageal stimulation in the evaluation of sinus node function in patients with sick sinus syndrome. Alboni P, Paparella N, Cappato R, Pedroni P, Candini GC, Antonioli GE. Divisione Cardiologica, Arcispedale S. Anna, Ferrara. G Ital Cardiol 1988 Jun;18(6):441-8. The purpose of this study was to find out whether transesophageal pacing could be utilized for assessment of sinus node function, besides Wenckebach point, in patients with sick sinus syndrome. In 17 patients with sino-atrial disease (group I) we compared the results of sinus node tests obtained both in the basal state and after pharmacological autonomic blockade by endocavitary stimulation and 24 hours later, by transesophageal pacing. In another group of 17 patients with sino-atrial disease (control group) we compared the results obtained from two endocavitary studies. In group I, sinus cycle length and corrected sinus recovery time did not show significant differences between the two studies either the basal state or after autonomic blockade, whereas sino-atrial conduction time was more prolonged during esophageal pacing (P less than 0.01). In the control group, sinus node measures did not show significant differences between the two studies. In group I, the following coefficients of correlation were obtained: A) in the basal state sinus cycle length, r = 0.65, corrected sinus recovery time, r = 0.57, sinoatrial conduction time, r = 0.52; B) after autonomic blockade sinus cycle length, r = 0.95, corrected sinus recovery time, r = 0.62 and sino-atrial conduction time, r = 0.53. In the basal state, the correlation for sinus cycle length and corrected sinus recovery time between the two studies was lower in the "study group" than in the "control group" (P less than 0.05). However, after autonomic blockade the correlation for sinus node measures did not show any significant differences between the two groups of patients.

    The role of an electropharmacological transesophageal test in the prevention of paroxysmal atrial fibrillation. Experience with flecainide. De Sisti A, Matteucci C, Patrissi T, Accogli S, Di Lorenzo M, Sasdelli M, Ciolli A, Lo Sardo G, Palamara A Divisione di Cardiologia, Ospedale Sandro Pertini, Roma. G Ital Cardiol 1998 Dec;28(12):1391-9. BACKGROUND: The management of patients with paroxysmal atrial fibrillation (AF) is unsuccessful, because AF recurs in about 50% of patients despite an antiarrhythmic treatment. Usefulness of non-pharmacological strategies is available in a limited subset of patients and it does not present a global solution to the problem. At present, treatment with antiarrhythmic agents is the only available tool in patients with AF recurrence. The aim of this study was to assess the predictive value of the electropharmacological transesophageal (TE) test in the management of patients with paroxysmal AF treated by flecainide. METHODS: In 32 patients, ranging in age from 38 to 70 years (mean: 59 +/- 12 years), with documented episodes of paroxysmal AF (mean: 5.6 +/- 3.7 episodes/last year), we performed an electrophysiological transesophageal (TE) test following pharmacological wash-out. An aggressive protocol was used: step A: 10 sec atrial burst at Wenckebach point + 10 bpm, 200 and 250 bpm; step B: 10 sec atrial bursts at 300, 400, 500 and 600 bpm; step C: 8 sec increasing rate burst from 200 to 800 bpm. Induction of sustained AF (> 1 min) was considered the end-point. Patients were treated with flecainide 100 mg bid and a second TE test was performed at the steady-state, with an identical induction protocol and end-point. Based on the response of the second test, patients were divided into responders (R Group: non-inducible AF) and non-responders (NR Group: inducible, sustained AF). Patients were followed-up by periodical controls and contacted by telephone to confirm their clinical status. RESULTS: Sustained AF was induced in 30 patients (94%) at the first TE study. Eight of them dropped-out at the time of the second TE test (6 patients for lack of consent, 1 patient for side-effects and another one for proarrhythmic effects). In the mean follow-up of 15 +/- 6 months, among patients who underwent a second TE test, AF recurrence was documented in 2 out of 14 patients from the R Group and in 7 out of 10 patients from the NR Group (p < 0.01). There were 4 AF episodes in the R Group and 19 in the NR Group (p < 0.001). We did not find significant statistical differences between the two groups in terms of age, sex, body weight, AF episodes/past year, P-wave duration, left atrial dimension, structural heart disease, AF duration at the first TE test and follow-up duration. In five patients from the NR Group with induced AF lasting > 5 min, the percentage of recurrence was 100% and there were 16 AF episodes. Global percentage of patients with recurrence was 37%. CONCLUSIONS: Flecainide is effective in reducing the incidence of AF and results are similar to other antiarrhythmic agents generally used. The electropharmacological TE test might be a useful tool to predict the response to an antiarrhythmic treatment.

    Catheter ablation of pulmonary vein foci for atrial fibrillation: PV foci ablation for atrial fibrillation. Shah DC, Haissaguerre M, Jais P. Thorac Cardiovasc Surg 47 Suppl 3:352-6, 1999. While experimental and human mapping studies have documented multiple wavelet reentry as the electrophysiological mechanism maintaining atrial fibrillation, recent evidence shows that nearly all paroxysms of atrial fibrillation are initiated by trains of rapid discharges from the pulmonary veins. Radiofrequency catheter ablation targeting these initiating triggers has resulted in an overall 69% freedom from atrial fibrillation at a follow-up of 8 +/- 4 months in a population of 110 patients with paroxysmal atrial fibrillation. Six of the targeted pulmonary veins (4%) developed pulmonary vein stenosis; none requiring specific treatment. Catheter ablation of pulmonary vein foci initiating atrial fibrillation is therefore an effective curative modality for paroxysmal atrial fibrillation. 

    Chiaranda G, Di Guardo G, Doria G, Castelli D, Lazzaro A, Mangiameli S. Servizio di Cardiologia con UTIC, Azienda Ospedaliera Garibaldi Catania. G Ital Cardiol 1999 Jan;29(1):59-62. BACKGROUND: Atrial fibrillation (AF) is common in patients with sick sinus syndrome (SSS) treated with dual-chamber pacing and it may complicate their management. This study was undertaken to establish the usefulness of atrial vulnerability (AV), determined by means of transesophageal electrophysiological study (TES), in predicting the risk of developing AF and in deciding the type and program of pacemaker (PM) to be implanted in patients with SSS. METHOD: AV was assessed preoperatively using TES in 81 consecutive patients with SSS. AV (AF > 1 min) was divided into "low threshold" (induction with burst < or = 300/min) and "high threshold" (induction with burst > or = 350 min or with incremental ramp). The PM was programmed to ensure constant atrial capture in all patients. Follow-up lasted three years. No patients received antiarrhythmic drugs. RESULT: AV was positive in 52% of patients (Group A) and negative in 48% of patients (Group B). A history of
    paroxysmal AF was present in 52% of patients in Group A and in 12% of patients in Group B. At follow-up, 38% of Group A and 2% of Group B patients had chronic AF. AV had sensitivity, specificity, positive predictive value (ppv) and negative predictive value (npv) of 94, 59, 38 and 97%, respectively. Thirty-eight percent of patients showed low threshold vulnerability, with sensitivity, specificity, ppv and npv of 87, 92, 87 and 93%, respectively. Sensitivity, specificity, ppv and pnv for history of AF were 93, 100, 98 and 84%, respectively. When the vulnerability threshold and the history of paroxysmal AF were considered together, the sensitivity, specificity, ppv and npv was 94, 100, 100 and 83%, respectively. Multivariate analysis was shown to be an independent predictive value only for history of AF (p = 0.0002). CONCLUSION: AV determined by means of TES, especially with a low induction threshold, shows excellent sensitivity and specificity in evaluating the risk of chronic AF. It could be useful in patients with SSS undergoing cardiac pacing who have never had AF, thus allowing a more accurate choice of the type and program of PM to be implanted. Case histories of paroxysmal AF could represent useful criteria for selecting patients at a high risk of developing chronic AF.