• Clinical Abstracts

    Clinical Abstracts on Transesophageal Atrial Pacing and Recording in Children and Infants

    Transesophageal indirect atrial pacing for open-heart surgery in children. Sung CS; Tsai SK; Chu M; Lee TY. Veterans Hosp-Taipei. Chung Hua I Hsueh Tsa Chih (Taiwan), 1995 55(1) p58-63. BACKGROUND. Transesophageal atrial pacing (TAP) has been successfully applied for clinical use for more than 30 years. Not only for cardiac pacing, or diagnosis and treatment of rhythmic disturbance but also for assessing the presence and severity of coronary artery disease and maintaining adequate heart rate can TAP provide satisfactory effect. In this study we applied TAP on children undergoing the cardiac surgery to evaluate its efficacy and side effects during such major surgery. METHODS. Twenty-four children (15 M and 9 F) undergoing open-heart surgery with informed consents were included in this study. After induction of anesthesia the bipolar pacing electrode (TAPCATH, CardioCommand) was inserted into esophagus through the nose until the ideal site for atrial pacing was found by monitoring the esophageal ECG lead (lead I), and then initiation of atrial pacing was performed by applying the transesophageal cardiac stimulator (CardioCommand). Continuous ECG, arterial blood pressure and central venous pressure (CVP) were simultaneously monitored and recorded. Patient's height, inserted length of the pacing electrode, current and pulse duration for effective atrial pacing were also recorded. RESULTS. The effective rate for initiating sinus tachycardia (atrial capture) by applying TAP was 79.2% (19/24) in our study. For effective atrial pacing the average current was 11.6 +/- 2.4 mA, the average stimulus pulse duration was 4.8 +/- 1.0 ms, and the average inserted length of bipolar electrode was 19.1 +/- 2.2 cm. CONCLUSIONS. TAP method can be applied satisfactorily in children undergoing cardiac surgery. If urgent cardiac pacing must be applied in these patients TAP would be a choice.

    Diagnostic and therapeutic use of transesophageal atrial pacing in children. Janousek J. Center of Pediatric Cardiology and Cardiac Surgery, Prague. Int J Cardiol 25(1):7-14, 1989. 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.

    Thresholds for transesophageal atrial pacing. Dick M, Campbell RM, Jenkins JM. C.S. Mott Children's Hospital, Ann Arbor, MI. Cathet and Cardiovas Diag. 10:507-513, 1984. To determine the thresholds for transesophageal atrial capture, as well as factors that may influence the thresholds, we measured the minimal current and pulse width required to pace the atria through transesophageal bipolar lead systems in 12 patients, ranging in age from 1 day to 19 years, during 19 episodes of reentran supraventricular tachycardia. Depending on patients' age and size several electrode catheters were used. The protocol called for 1-msec stepwise increments in pulse width. At each pulse width the current was increased by 1 mA until capture was achieved. The mean minimal pulse width and mean minimal current required for capture were 5.8 msec and 13.6 mA, repsectively. Atrial capture was achieved in 75% of atempts at a pulse width and current <= 6.5 msec and 17.5 mA respectively. No correlation between current and pulse width on the one hand and age, height, weight or body surface area on the other were detected. Likewise, neither electrode type nor existence of structural heart disease influenced the threshold required for capture. We conclude that atrial capture can be readily achieved through transesophageal electrodes and is not influenced by subject's age or size.

    Atrial flutter in infancy: diagnosis, clinical features, and treatment. Dunnigan A, Benson W Jr, Benditt DG. Pediatrics 75(4):725-729, 1985. The clinical features and treatment of atrial flutter in eight infants (four male and four female) less than 2 months of age are presented. Atrial flutter was noted during the first week of life in six of the infants and between 6 and 8 weeks of life in the other two infants. Four of the eight infants had associated structural or functional cardiovascular disease, and in three infants a central venous pressure catheter was present in the atrium at the time atrial flutter was diagnosed. Classic flutter waves were apparent on 12-lead ECGs in only two infants. In six infants, flutter waves were not obvious on standard ECGs, but transesophageal electrogram recordings demonstrated the presence of atrial flutter with second degree atrioventricular block. The atrial cycle length during flutter ranged from 135 to 180 ms (mean 149 ms; mean atrial rate 403 beats per minute); there was a 2:1 ventricular response to atrial flutter. Successful termination of atrial flutter was accomplished using three modes of electrical cardioversion in seven of the eight infants: direct current cardioversion in one, transvenous atrial pacing in one, and transesophageal atrial pacing in five. One asymptomatic infant converted to normal sinus rhythm 24 hours following digoxin administration. One infant had multiple atrial flutter recurrences and required chronic procainamide therapy. In seven of the eight infants, no recurrences have been noted in 6 months to 3 1/2 years of follow-up. These results demonstrate that atrial flutter may be difficult to diagnose in infants with tachycardia unless transesophageal electrogram recording is utilized for evaluation. 

    Clinical correlates of dysrhythmias requiring an esophageal ECG for accurate diagnosis in patients with congenital heart disease. Bushman GA. Arkansas Children's Hospital. J Cardiothorac Anesth 1989, 3(3):290-4. Esophageal electrocardiography (EsECG) is a useful adjunct in the diagnosis of dysrhythmias that are difficult to diagnose with a conventional ECG. This study was designed to evaluate which type of dysrhythmias required the EsECG for proper diagnosis and what factors produced the rhythm problems. Sixty-eight pediatric patients undergoing cardiac surgery were studied. After release of the aortic cross-clamp, the cardiac rhythm was analyzed by a standard limb-lead ECG at five-minute intervals. Twenty-six of 68 patients exhibited rhythms during reperfusion that required the EsECG for definitive diagnosis. This group of patients was younger, had longer durations of cardiopulmonary bypass and aortic occlusion, and required more time and interventions to achieve a normal sinus rhythm. The likelihood of difficult dysrhythmias was not related to the type of surgical procedure performed. 

    Atrial pacing for conversion of atrial flutter in children. Campbell RM, MacDonald D, Jenkins JM  C.S. Mott Children's Hospital, Ann Arbor, MI. Pediatrics 1985 Apr;75(4):730-6. Twenty-three successive patients with 27 different episodes of sustained atrial flutter were treated with atrial pacing for conversion of the tachyarrhythmia; 15 patients with 16 episodes of atrial flutter underwent intracardiac right atrial pacing and 8 patients with 11 episodes of atrial flutter were treated with transesophageal atrial pacing. Ten of sixteen episodes (63%) and 8/11 episodes (73%) were successfully converted using intracardiac and transesophageal techniques, respectively. Mean flutter cycle length for all 27 episodes was 219 msec (mean heart rate 274 bpm); successful pacing conversion cycle length (n=15) was 72% of the flutter cycle length. Hemodynamic, electrophysiologic, and x-ray data were not predictive of conversion by either technique. Induction of localized atrial fibrillation or failure to meet critical pacing criteria may explain pacing failures. Based on this experience we recommend a trial of transesophageal atrial pacing for acute conversion of any episode of atrail flutter in children prior to direct current cardioversion. 

    Conversion of atrial flutter in pediatric patients by transesophageal atrial pacing: a safe, effective, minimally invasive procedure. Rhodes LA, Walsh EP, Saul JP. Children's Hospital, Boston. Am Heart J 130(2):323-7, 1995. Atrial reentry tachycardia, often termed atrial flutter, is an arrhythmia that is uncommon in the general pediatric population but is seen frequently in patients with congenital heart disease. One goal in treating the arrhythmia is to terminate it, returning the atrium to its underlying rhythm. This report describes the use of transesophageal atrial pacing to attempt termination of atrial reentry in 102 pediatric patients (158 episodes). The patients ranged in age from 1 hour to 41.5 years. Conversion was successful for 112 (71%) of 158 episodes. Six of the 112 episodes required an infusion of procainamide after initial attempts at pacing led to atrial fibrillation. There were no significant differences between the ages of patients or the duration of the tachycardia in comparing successful versus unsuccessful conversions. In contrast, the atrial cycle lengths for the successfully converted tachycardias were significantly greater than for unsuccessful attempts. Transesophageal atrial pacing is a safe and effective means of terminating atrial flutter in the pediatric population. It is minimally invasive, it can often be performed in an outpatient setting, and the technique may occasionally be facilitated by infusion of intravenous procainamide. 

    Reciprocating supraventricular tachycardia in children: low rate at rest as a major factor related to propensity to syncope during exercise. Drago F, Turchetta A, Calzolari A, Giordano U, Di Ciommo V, Santilli A, Pompei E, Ragonese P. Department of Pediatric Cardiology, Bambino Gesu Children's Hospital, Scientific Institute of Research, Rome, Italy. Am Heart J 1996 Aug;132(2 Pt 1):280-5. Reciprocating supraventricular tachycardia may have several clinical presentations, with symptoms often more severe during exercise or emotional stress. This study shows by using transesophageal atrial pacing, the factors related to syncope during exercise. Between May 1989 and June 1994, transesophageal atrial pacing was performed at rest and during exercise in 75 children aged > 6 years with suspected or documented episodes of paroxysmal supraventricular tachycardia. Reciprocating supraventricular tachycardia could be induced both at rest and during exercise in 22 patients (8 girls, 14 boys; mean age 10.6 +/- 2.7 years, range 7 to 15 years) with ventriculoatrial interval < 70 msec in 11 patients and > 70 msec in 11. At rest, all patients had palpitations caused by the induction of tachycardia. After conversion to sinus rhythm, when tachycardia was induced during exercise, symptoms did not change in 14 patients (group A), whereas symptoms worsened (presyncope) in eight (group B). The statistical analysis showed a significant difference of mean reciprocating supraventricular tachycardia rate at rest between the two groups (group A, 211 +/- 23 beats/min; group B, 173 +/- 33 beats/min; p = 0.0057) and reciprocating supraventricular tachycardia rate variation from rest to exercise (group A, 62 +/- 18 beats/min; group B, 105 +/- 24 beats/min; p = 0.0001). These data suggest that children with low tachycardia rate during normal activities may have syncope more frequently, independently of the tachycardia rate during exercise or emotional stress. 

    Transesophageal electroconversion of atrial reentrant tachycardias early or late following surgery for congenital heart disease. Hessling G, Brockmeier K, Rudiger HJ, Ulmer HE. Abt. Padiatrische Kardiologie Universitatskinderklinik, Heidelberg. Z Kardiol 88(2):97-102, 1999. Atrial reentrant tachycardias (ART) are a potentially life-threatening complication in survivors of congenital heart disease surgery. From July 1993 to December 1997, temporary transesophageal pacing was used to convert 29 tachycardia episodes in 19 patients. At the time of the first tachycardia episode, patients' ages were 1 month to 26 years (mean 9.8 yrs). Time from operation to onset of first tachycardia episode ranged from 1 day to 19 years. Onset was within the first 2 weeks postoperatively in 6 patients and occurred later in 13 patients (1 to 19 years after operation). Postoperative pacemaker implantation had been performed in 2 pts; 17 of 19 pts were receiving antiarrhythmic medication. After placing a quadripolar transesophageal catheter, atrial and ventricular signals were recorded and atrial stimulation performed. Atrial cycle length of tachycardia ranged from 160-380 ms with 1:1 to 4:1 AV conduction. Temporary transesophageal pacing was performed following an algorithm starting with 4 extrastimuli (20 ms below atrial cycle length of tachycardia). Tachycardia terminated in 27 of 29 cases (93%) without complications. In 3 cases, conversion was achieved by pacing after amiodarone 5 mg/kg i.v. After tachycardia conversion, sinus- or pacemaker rhythm was present in 20 cases. In 9 cases atrial fibrillation was recorded; spontaneous conversion to sinus rhythm occurred after a maximum of 3 min (7 cases) or persisted and required direct current cardioversion (2 cases). In conclusion, transesophageal atrial pacing is an effective, relatively noninvasive method for conversion of atrial reentrant tachycardias after operation for congenital heart disease. 

    Comparison of transesophageal and intracardiac electrophysiologic studies in characterization of supraventricular tachycardia in pediatric patients. Samson RA, Deal BJ, Strasburger JF, Benson DW Jr. Department of Pediatrics, Northwestern University, Children's Memorial Hospital, Chicago, Illinois, USA. J Am Coll Cardiol 26(1):159-63, 1995. OBJECTIVES. This study sought to determine the accuracy of transesophageal electrophysiologic studies in diagnosing and characterizing various mechanisms of supraventricular tachycardia in pediatric patients. BACKGROUND. Transesophageal electrophysiologic studies are a relatively noninvasive means of characterizing supraventricular tachycardia. Although widely used, to our knowledge no data exist that directly compare information obtained from transesophageal electrophysiologic studies with that from intracardiac electrophysiologic studies. METHODS. We reviewed the records of 57 pediatric patients undergoing both transesophageal and intracardiac electrophysiologic studies at our institution. The results of these studies were compared with respect to mechanism of tachycardia, localization of accessory atrioventricular (AV) connections (if present) and characterization of anterograde accessory connection conduction properties. RESULTS. Tachycardia mechanisms were concordant in 56 of 57 patients: orthodromic reciprocating tachycardia in 43, antidromic reciprocating tachycardia in 1, both orthodromic and antidromic tachycardia in 2, AV node reentrant tachycardia in 5, atrial reentrant tachycardia in 4 and ectopic atrial tachycardia in 2. Of 29 patients with orthodromic reciprocating tachycardia using a concealed accessory connection, transesophageal study predicted the accessory connection site through changes induced by transient bundle branch block in 12. By the Bland-Altman method in 14 patients with pre-excitation, the anterograde accessory connection effective refractory period determined by transesophageal study compared favorably with that determined by intracardiac study (mean difference 5.0 ms, limits of agreement -55 and 65 ms). CONCLUSIONS. Transesophageal electrophysiologic studies are a highly accurate means of diagnosing and characterizing various mechanisms of supraventricular tachycardia in pediatric patients. 

    Bundle branch block during orthodromic reciprocating tachycardia onset in infants. Goldstein M, Dunnigan A, Milstein S, Benson DW Jr. Department of Pediatrics, University of Minnesota Hospital. Am J Cardiol 1989 Feb 1;63(5):301-6. Transesophageal electrophysiologic studies were performed in 58 infants (age less than or equal to 1 year, median 10 days) with electrocardiographically documented orthodromic reciprocating tachycardia (ORT). The aim was to evaluate the occurrence, type and electrophysiologic effects of bundle branch block (BBB) during ORT onset. Of the 58 infants, 25 (43%) had BBB with pacing-induced tachycardia onset. BBB was initiated by single or double premature atrial extrastimuli and by burst atrial pacing; 4 infants also demonstrated BBB with spontaneous ORT onset during transesophageal study. Two of 25 infants had BBB only after intravenous procainamide. Comparison of the 25 infants exhibiting BBB at ORT onset with the 33 infants not demonstrating BBB revealed that age was not statistically different in the 2 groups, but that severity of illness (based on a 1 to 3 scale) was greater (p less than 0.05) and normal QRS ORT cycle length was shorter (p less than 0.02) in the infants with BBB. Of the 25 infants with BBB at ORT onset, 17 had left BBB, 3 had right BBB and 5 had both left and right BBB. Ventriculoatrial interval or cycle length increases during ORT with BBB in 16 of 25 (64%) infants suggested left free wall-accessory atrioventricular connections. 

    Natural history of isolated atrial flutter in infancy. Mendelsohn A, Dick M 2d, Serwer GA. C.S. Mott Children's Hospital, Ann Arbor, MI. J Pediatr 1991 Sep;119(3):386-91. To clarify the natural history of isolated (i.e., without associated congenital cardiac anomalies) atrial flutter in infancy, we reviewed the clinical course in nine patients who were seen with this arrhythmia in the first year of life (range 1 day to 4 months). Atrial flutter was identified by the typical sawtooth pattern in leads II, III, and aVF of the surface electrocardiogram or the pattern of atrial flutter on an atrial electrogram recorded through the esophagus. The mean cycle length of the atrial flutter was 151 msec (atrial rate 397 beats/min). Six of the nine patients had other perinatal problems, such as immune and nonimmune hydrops fetalis (two patients), pneumonia (one patient), anemia (five patients), or low birth weight (one patient). In all patients the rhythm reverted to normal, either spontaneously (two patients), with overdrive pacing (four patients), or after oral digoxin therapy (three patients). No consistent temporal relationship between digoxin administration and conversion was observed; conversion was instantaneous in the four patients who received atrial overdrive pacing. Four patients were discharged receiving digoxin therapy (6 months to 1 year). One patient had supraventricular tachycardia after discharge that was controlled with digoxin. No recurrence of atrial flutter was observed among the nine patients during a mean follow-up of 6.8 years (range 0.2 to 20 years). We conclude that isolated atrial flutter in infancy is rare, has a good prognosis, may be related to transient perinatal events, and often spontaneously converts to normal sinus rhythm; however, when it does not, it will respond to transesophageal pacing.

    Supraventricular tachycardia in infancy: evaluation, management, and follow-up. Etheridge SP, Judd VE. Department of Pediatrics, University of Utah School of Medicine, Primary Children's Medical Center, Salt Lake City. Arch Pediatr Adolesc Med 1999 Mar;153(3):267-71  BACKGROUND: Supraventricular tachycardia (SVT) occurs frequently in infancy. However, some infants have no recurrences after the initial presentation of SVT, and approximately 30% of infants lose SVT inducibility by 1 year of age. OBJECTIVE: To determine whether features at presentation, tachycardia characteristics, or data from an esophageal electrophysiology (EP) study could predict which infants will not require antiarrhythmic medication and which infants will not have inducible SVT at 1 year. DESIGN: Clinical and tachycardia characteristics at presentation of SVT and data obtained from an esophageal EP study were evaluated prospectively. Patients were followed up for 1 year, and an esophageal EP study was performed to evaluate for continued SVT inducibility. SETTING: Primary Children's Medical Center is a tertiary care hospital affiliated with the University of Utah that provides primary care to local patients and is a referral center for a 4-state region. PATIENTS: All infants aged 3 months or younger who presented with SVT between August 1995 and October 1997 were evaluated. INTERVENTIONS: An esophageal EP study was performed at diagnosis and at 1 year. RESULTS: The SVT was controlled in all 33 infants. At the initial esophageal EP study, the mechanism of SVT was atrioventricular node reentry in 5 patients (15%) and orthodromic reciprocating tachycardia via an accessory atrioventricular connection in 28 patients (85%). One infant was lost to follow-up, 5 never required medication, 11 had SVT controlled with propranolol hydrochloride, 10 had SVT controlled with amiodarone, and 6 required more than 1 medication. Of the 21 patients who have reached 1 year of age, 16 (76%) were not taking any medication and were free of SVT at the time of follow-up. All 16 patients without clinical SVT have undergone a follow-up esophageal EP study, and 11 of 16 had inducible SVT on esophageal EP study. Thus, of the 21 one-year-old patients, 5 (24%) no longer had clinical or inducible SVT. CONCLUSIONS: Control of SVT was possible in all patients. Clinical episodes of SVT were uncommon after discharge, yet most still had inducible SVT at 1 year of age. No data at presentation or initial esophageal EP study were predictive of the clinical course or of continued SVT. 

    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 74(4):353-6, 1994.  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. 

    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.

    Value of the esophageal approach in the diagnosis, treatment and therapeutic surveillance of arrhythmia in children. Moquet B, Chantepie A, Fauchier JP, Cosnay P, Huguet RG, Laugier J. Arch Fr Pediatr 1989 Jan;46(1):11-7. For the past few years, a new method for the investigation and treatment of arrhythmias has been used: transoesophageal atrial pacing and recording (TAPR). In the light of 6 cases observed recently, we review the technical aspects and the indications for TAPR. A bipolar stimulation catheter is inserted in the oesophagus and positioned in the area where the atrial wave of greater amplitude is recorded. Atrial stimulation is done with impulses of long duration obtained with a special stimulator. Two cases validated this technique which was effective to correct atrial flutter in a neonate with heart failure resistant to medical treatment as well as in a 5 year-old child. The value of TAPR as a diagnostic tool in cases of tachycardia is discussed in the context of 2 cases: a 5 week-old with wide QRS and a 14 month-old with narrow QRS. Finally, the value of TAPR for monitoring the efficacy of anti-arrhythmia medications is illustrated by 4 cases of supraventricular tachycardia, in whom the optimal dosage of the anti-arrhythmic drug used was determined with the help of TAPR-induced tachycardia. The current literature concerning the technique, indications and results of TAPR are reviewed. This method is likely to take a great importance for the study and treatment of supraventricular arrhythmias in children.

    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.

    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 sinusoidal 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. 

    Prediction of digoxin treatment failure in infants with supraventricular tachycardia: role of transesophageal pacing. Benson DW Jr, Dunnigan A, Benditt DG, Thompson TR, Narayan A, Boros S. Pediatrics 1985 Feb;75(2):288-93. Transesophageal atrial pacing was used to initiate and terminate tachycardia in 24 infants (seven female and 17 male, aged 1 to 34 days) with ECG documentation of supraventricular tachycardia. Six infants received no chronic treatment, and chronic oral digoxin prophylaxis was administered to 18 infants in an effort to prevent recurrences of tachycardia. In these 18 infants, the effectiveness of digoxin therapy in preventing the initiation of tachycardia by transesophageal pacing was compared with its ability to prevent spontaneous recurrences of supraventricular tachycardia. While receiving chronic oral digoxin therapy, tachycardia could be reinitiated in 15/18 (83%) infants. In these infants, the cycle length of tachycardia and the atrioventricular interval were the same before and during chronic digoxin treatment. Three infants in whom tachycardia could not be initiated during chronic digoxin therapy had no spontaneous recurrences during 6 months of follow-up, whereas 10/15 (67%) infants in whom tachycardia could be reinitiated had clinically significant recurrences in spite of chronic digoxin therapy. Six infants who received no chronic drug treatment had no documented recurrences during 6 months of follow-up. This study demonstrates that digoxin was effective in preventing significant spontaneous recurrences of supraventricular tachycardia in only 8/18 (44%) infants treated with digoxin. The ability to initiate supraventricular tachycardia with transesophageal pacing may be useful in determining which digoxin-treated infants are at risk for recurrence. Finally, not all infants with supraventricular tachycardia require chronic prophylaxis; six of the untreated infants had no documented recurrences. 

    Ventricular fibrillation during transesophageal atrial pacing in an infant with Wolff-Parkinson-White syndrome. Kugler JD, Danford DA, Gumbiner CH. Section of Cardiology, Department of Pediatrics, University of Nebraska Medical Center, Omaha 68105. Pediatr Cardiol 1991 Jan;12(1):36-8. A complication of transesophageal atrial pacing in an infant with Wolff-Parkinson-White syndrome (WPW) is reported. A newborn infant born with fetal hydrops had recurrent supraventricular tachycardia (SVT) that required repeated successful conversion by transesophageal atrial pacing. Because of secondary left ventricular dysfunction, digoxin was administered. During repeat transesophageal atrial pacing for recurrent SVT, ventricular fibrillation occurred. Although it is unclear which of several possible contributing factors was responsible for the ventricular fibrillation, recommendations are appropriate to minimize the risk in infants with WPW. 

    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.

    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.

    Emergency 12-hour transesophageal stimulation in a 21-month-old infant. Paul T, Luhmer I, Wilken M, Kallfelz HC.Hannover. Anaesthesist 42(8):564-6, 1993. In a 21-month-old child with complex cyanotic congenital heart disease an aortopulmonary shunt was created as preparation for a modified Fontan operation. During the early postoperative period low cardiac output with right atrial pressures of 20 mm Hg developed due to a slow ventricular tachycardia (ventricular rate 135 bpm). Pharmacological interventions (isoprenaline 0.01 mg/kg hourly and lidocaine 1 mg/kg hourly were without any effect. As epicardial pacing leads had not been implanted during surgery, atrial pacing was performed via the transoesophageal route using a 9.5-F bipolar electrode catheter with an interelectrode distance of 15 mm. Atrial capture could be established with an impulse width of 9.9 ms and 10 mA output at a rate of 150 bpm. With restoration of atrioventricular synchronicity, right atrial pressure finally decreased to 10 mm Hg with consecutive stabilization of the cardiovascular status. After 12.5 h transoesophageal pacing could be stopped without any problems due to spontaneous cessation of ventricular tachycardia. No clinical signs of oesophageal injury were noted. It is concluded that transoesophageal pacing is a practical, safe and effective method for emergency cardiac pacing. 

    Fetoscopic transesophageal electrocardiography and stimulation in fetal sheep : A minimally invasive approach aimed at diagnosis and termination of therapy-refractory supraventricular tachycardias in human fetuses.  Kohl T, Kirchhof PF, Gogarten W, Reckers J, Asfour B, Witteler R, Haverkamp W, Eckardt L, Marcus AE, VanAken H, Breithardt G, Vogt J, Scheld HH. Departments of Pediatric Cardiology (T.K., J.R., J.V.), Cardiothoracic Surgery (T.K., B.A., H.H.S.), Cardiology and Angiology (P.F.K., W.H., L.E., G.B.), Anesthesia (W.G., A.E.M., H.V. ), and Obstetrics (R.W.), University of Munst. Circulation 17;100(7):772-6, 1999. Background--Therapy-refractory supraventricular tachycardia commonly results in hydrops and death in human fetuses. The purpose of this study in fetal sheep was to assess the feasibility of a minimally invasive fetoscopic approach for fetal transesophageal electrocardiography and stimulation aimed at diagnosis and termination of these tachycardias. Methods and Results --We studied a total of 10 fetal sheep (87 to 103 days of gestation; term=145 days). We entered the amniotic cavity using a percutaneous fetoscopic approach and placed various electrophysiology catheters into the fetal esophagus. We recorded the number of animals in which fetoscopic transesophageal electrocardiography and stimulation were successful and assessed pacing success and thresholds for different catheters. In addition, we monitored for potential adverse effects from stimulation and for other complications of the operation. Recording of transesophageal electrocardiograms was successful in all fetal sheep. Capture during stimulation was successfully documented by additional fetal bipolar surface electrocardiograms in 7 fetuses. In fetuses in which fetal surface electrocardiograms were not recorded, pacing stimulus artifacts interfered with documentation of capture. Although stimulation thresholds were high, the maternal rhythm\ was not affected by fetal stimulation. Conclusions--Fetoscopic fetal transesophageal electrocardiography and stimulation are feasible in fetal sheep. This minimally invasive approach might have the potential to improve diagnosis and management of therapy-refractory supraventricular tachycardias in human fetuses. 

    Doppler echocardiography with extended transesophageal atrial pacing: predicting the efficacy of permanent atrial pacing in the patient with a small left ventricle and sinus node dysfunction. Liske MR, Duffy CE, Gidding SS, Rocchini AP. Division of Pediatric Cardiology, Children's Memorial Hospital, Chicago, IL. Pediatr Cardiol 1999 May-Jun;20(3):218-20. A 2100-g neonate underwent a two-ventricular surgical repair of a right ventricle-dominant unbalanced atrioventricular septal defect associated with the heterotaxy syndrome and sinus node dysfunction. Postoperative congestive heart failure persisted despite bradycardia management by temporary ventricular pacing. Spectral Doppler echocardiographic analysis of pulmonary venous inflow and aortic outflow patterns demonstrated significant improvement with transesophageal atrial pacing. Extended transesophageal pacing was performed for two days, resulting in dramatic clinical improvement. This is the first report of extended transesophageal atrial pacing complementing Doppler echocardiography predicting an improved outcome with permanent atrial pacing. 

    Emergency ventricular pacing from the esophagus in infancy. Serwer GA, Eckerd JM, Kelly EE, Armstrong BE. Duke Univ Med Ctr. Am J Cardiol 1986, 58(11): 1105-1106. Use of transesophageal ventricular pacing for emergency cardiac pacing has been reported in adults, but not in infants. Emergency pacing has heretofore required introducion of a transvenous catheter. In this report, we describe an infant who required emergency ventricular pacing which was successfully performed using an esophageal catheter.

    A Discussion of Fetal and Neonatal Arrhythmias. Ann Dunnigan, M.D., Minneapolis Heart Institute. From an interview with Guidant Corp. http://www.guidant.com/physician/aicd99sum/discussion.htm 
    AICD Advances: Can you discuss any interesting case studies you have encountered? 
    Dr. Dunnigan: A female fetus was diagnosed at 30 weeks with a type of heart failure called hydrops fetalis, and she had a heart rate of 300 bpm. The baby was delivered by cesarean section at that time, because of the obstetrician?s concern for the baby?s safety. Because of marked edema with this type of heart failure, however, it was very difficult to intubate her. An echocardiogram later showed minimal heart contractions, so we were reluctant to give her intravenous antiarrhythmic drugs. We instead inserted an esophageal lead connected to a stimulator that, when necessary, delivered two or three paced beats to terminate the tachycardia. This worked well for about 24 hours, until incessant tachycardia developed. As soon as we stopped pacing the tachycardia, it would begin again. The tachycardia wasn?t originating with premature atrial contractions or single extra stimuli. Another mechanism, sinus acceleration, was involved with the tachycardia initiation. We then paced the baby?s atrium at a rate of 320 bpm, and the ventricular rate decreased to 160 bpm. We continued this for two or three days, stopping the pacing occasionally to see what would happen. Within a few minutes of pacing cessation, the tachycardia always recurred. Several days later, however, her heart failure had improved and, once again, we needed to pace only during tachycardia recurrence. After further improvement of her heart failure, she was managed with amiodarone for about nine months. She was one of the lucky infants who eventually outgrew her condition. 
    I was called in on another case because a fetus had been diagnosed with atrial flutter at 32 weeks. The atrial rate was 400 bpm; the ventricular rate was 200 bpm. The fetus did not have heart failure, but we needed to treat the arrhythmia via the mother, so we admitted her to the hospital. There have been many reports of quinidine crossing the placenta to deliver an adequate dosage to the baby, so we gave the mother quinidine/ After several days of monitoring we noted that the atrial flutter had stopped. When the baby was born his esophageal pacing study revealed that he had WPW syndrome and inducible orthodromic tachycardia. Of course older patients have atrial fibrillation in association with WPW, but I believe that this baby?s atrium was too small to fibrillate, and he had atrial flutter instead.

    Myocardial ischaemia un-masked by transesophageal atrial pacing combined with two-dimensional transthoracic echocardiography in a pediatric patient: a case report. De Caro E, Pongiglione G.Istituto G. Gaslini, Servizio di Cardiologia, Genova, Italy. Int J Cardiol 66(2):133-5, 1998. We describe a case of a child operated on for an anomalous origin of the left coronary artery from the pulmonary artery and proximal hypoplasia of the anomalous coronary, in whom residual inducible myocardial ischaemia was detected by means of transesophageal atrial pacing combined with transthoracic echocardiography.

    Complications associated with pediatric cardiac catheterization. Vitiello R, McCrindle BW, Nykanen D, Freedom RM, Benson LN. The Hospital for Sick Children, Toronto. J Am Coll Cardiol 32(5):1433-40, 1998. OBJECTIVES: The aim of this study was to determine the relative risks of pediatric diagnostic, interventional and electrophysiologic catheterizations. BACKGROUND: The role of the pediatric catheterization laboratory has evolved in the last decade as a therapeutic modality, although remaining an important tool for anatomic and hemodynamic diagnosis. METHODS: A study of 4,952 consecutive pediatric catheterization procedures was undertaken. RESULTS: Patient ages ranged from 1 day to 20 years (median 2.9 years). One or more complications occurred in 436 studies (8.8%) and were classified as major in 102 and minor in 458, with vascular complications (n=189; 3.8% of procedures) the most common adverse event. Arrhythmic complications (n=24) were the most common major complication. Death occurred in seven cases (0.14%) as a direct complication of the procedure and was more common in infants (n=5). Independent risk factors for complications included a young patient age and undergoing an interventional procedure. CONCLUSIONS: Complications continue to be associated with pediatric cardiac catheterization. Efforts should be directed to improving equipment for flexibility and size, and finding alternative methods for vascular access. Patient age and interventional studies are risk factors for morbidity and mortality.