• Clinical Abstracts

    Clinical Abstracts on Transesophageal Pacing for Temporary Heart Rate Acceleration and Management of Hemodynamics

    Transesophageal atrial pacing for intraoperative sinus bradycardia or AV junctional rhythm: feasibility as prophylaxis in 200 anesthetized adults and hemodynamic effects of treatment. Atlee JL 3d; Pattison CZ; Mathews EL; Hedman AG. Medical College of Wisconsin. J Cardiothorac Vasc Anesth (United States), Aug 1993, 7(4) p436-41. Sinus bradycardia (SB) or atrioventricular junctional rhythm (AVJR) may produce circulatory insufficiency in anesthetized surgical patients, especially those with cardiovascular disease. Chronotropic drugs have been the preferred initial treatment, except when epicardial pacing is available. Alternative methods include transvenous or transcutaneous pacing. Drugs may be ineffective or have undesirable effects. Transvenous pacing is time consuming and risky, and transcutaneous pacing is not universally applicable or effective. Transesophageal atrial pacing (TAP) lacks these disadvantages, but unavailability of equipment and unfamiliarity with the method has discouraged widespread use. Feasibility of TAP as prophylaxis for intraoperative SB or AVJR was tested with approved or investigational devices in 200 anesthetized surgical patients, not necessarily with cardiovascular disease or having cardiac surgery. Of these, 84 later had incidental SB or = 60 beats/min, and 23 of these 84 had SB or = 50 beats/min. Thirteen patients had AVJR (72 +/- 4 beats/min; mean +/- SEM). TAP at 80 beats/min for SB, or at a rate sufficient to overdrive AVJR, was effective initial treatment in all patients.

    Atrial pacing thresholds measured in anesthetized patients with the use of an esophageal stethoscope modified for pacing. Pattison CZ; Atlee JL 3d; Mathews EL; Buljubasic N; Entress JJ. Medical College of Wisconsin. Anesthesiology, May 1991, 74(5) p854-9. Transesophageal atrial pacing (TAP) with the use of standard, thermistor-equipped, esophageal stethoscopes, modified for pacing by incorporation of a 4-French, bipolar TAP probe (pacing esophageal stethoscope [PES]), was evaluated in 100 adult patients under general anesthesia. A commercially available TAP pulse generator supplied 10-ms pulses with current variable between 0 and 40 mA. Pacing distances (in centimeters) were measured from the infraalveolar ridge to midway between PES electrodes (1.5-cm interelectrode distance). Pacing thresholds (mA) were measured at the point of a maximum-amplitude P-wave (PMAX) in the bipolar esophageal electrogram and points 1 cm proximal or 1, 2, or 3 cm distal to PMAX. TAP (70-100 beats per min) was used for sinus bradycardia less than or equal to 60 beats per min (36 patients) or atrioventricular (AV) junctional rhythm (2 patients) and blood pressure changes with TAP documented. In male patients (n = 49), PMAX was 32.7 +/- 0.3 cm (mean +/- SE) and minimum pacing threshold 5.1 +/- 0.4 mA (range, 1-13 mA) at 33.6 +/- 0.3 cm (range, 30-37 cm). In female patients (n = 51), PMAX was 30.4 +/- 0.4 cm and minimum pacing threshold 4.4 +/- 0.4 mA (range, 2-14 mA) at 31.1 +/- 0.4 cm (range, 26-40 cm). TAP produced an average 13-16 mmHg increase in systolic, diastolic, or mean arterial pressure in patients with sinus bradycardia or AV junctional rhythm. There were no subjective patient complaints (epigastric discomfort, dysphagia) that could be attributed to TAP; objective evaluation (esophagoscopy) was not performed. It is concluded that TAP is widely applicable to anesthetized adults; low TAP thresholds can be obtained by first determining Pmax and positioning the PES electrode 1 cm or less distal to Pmax; and TAP can be used to increase blood pressure in patients with sinus bradycardia or AV junctional rhythm.

    Comparison of transesophageal atrial pacing with anticholinergic drugs for the treatment of intraoperative bradycardia. Smith I; Monk TG; White PF. University of Texas Southwestern Med Ctr. Anesth Analg, Feb 1994, 78(2) p245-52. We compared the effectiveness of atropine, glycopyrrolate, and a transesophageal atrial pacing (TAP) stethoscope for treating intraoperative bradycardia in 64 unpremedicated patients receiving a standardized sufentanil/N2O/vecuronium anesthetic. Patients were allocated randomly to receive either atropine, 5 micrograms/kg (Group 1), glycopyrrolate, 2.5 micrograms/kg (Group 2), or transesophageal atrial pacing (Group 3) after the onset of bradycardia, defined as a heart rate of or = 50 beats/min (or or = 60 beats/min with concurrent hypotension). Bradycardia occurred in 15 patients of each treatment group. The time required for the heart rate to increase to or = 70 beats/min was 270 (range 30-490), 270 (70-465), and 12 (2-30) s in Groups 1, 2, and 3, respectively. Although all patients in Group 3 responded to pacing at 150% of the threshold current, 10 patients in Group 1 and 8 patients in Group 2 required a second dose of anticholinergic medication before a heart rate response was observed. One patient in Group 2 required three doses, and another who did not respond even after four doses was treated with the TAP device. Bradycardia subsequently recurred in five patients in Group 1 and four patients in Group 2. Temporary recurrence of bradycardia occurred in seven patients in Group 3 due to outward migration of the pacing stethoscope. However, heart rates were more consistently maintained in paced patients. There were no significant differences in postoperative side effects between the three groups, or when compared with patients who did not receive treatment for bradycardia.

    Transesophageal atrial pacing reduces phenylephrine needed for blood pressure support during carotid endarterectomy. Borum SE, Bittenbinder TM, Buckley CJ. Department of Anesthesiology, Scott & White Clinic and Memorial Hospital, Texas A&M University System Health Science Center, College of Medicine, Temple 76508, USA. J Cardiothorac Vasc Anesth  14(3):277-80, 2000. OBJECTIVE: To determine whether transesophageal atrial pacing reduces phenylephrine requirement for blood pressure support during general anesthesia for carotid endarterectomy. DESIGN: Prospective randomized clinical study. SETTING: University hospital. PARTICIPANTS: Thirty-six patients undergoing elective carotid endarterectomy under general anesthesia. INTERVENTIONS: Adults of either sex (n = 36) received general anesthesia using a standardized anesthetic regimen for elective carotid endarterectomy. Phenylephrine requirements were measured in patients having carotid endarterectomy and randomized to phenylephrine infusion (group 1, 19 patients) or phenylephrine infusion plus transesophageal atrial pacing (group 2, 17 patients) to maintain systolic blood pressure within +/-20% of baseline systolic blood pressure. MEASUREMENTS AND MAIN RESULTS: Measurements included (1) the amount of phenylephrine required in each group, (2) the variance of systolic blood pressure outside the desired range, and (3) the occurrence of postoperative electrocardiogram or myocardial enzyme changes suggesting myocardial ischemia. The average requirement for phenylephrine was less for group 2 (0.28+/-0.16 microg/kg/min) than for group 1 patients (0.46+/-0.23 microg/kg/min) (p = 0.02 by t-test). CONCLUSIONS: Under controlled conditions of general anesthesia for carotid endarterectomy, transesophageal atrial pacing reduced by 40% the amount of phenylephrine needed for blood pressure support and helped in the treatment of disadvantageous sinus bradycardia.

    Transesophageal atrial pacing (TAP) for sinus bradycardia during coronary artery bypass grafting: comparison of TAP to intermittent bolus gallamine. Tomichek RC, Shields JA, Zimmerman RE. St. Thomas Hospital, Nashville. J Cardiothorac Vasc Anesth 1995, 9(3) p259-63. OBJECTIVE: To assess the relative efficacy of a pacing esophageal stethoscope and intermittent boluses (40 mg) of gallamine in correcting sinus bradycardia (SB) during coronary artery surgery. DESIGN: The study was prospective, randomized, and controlled. SETTING: A community hospital. PARTICIPANTS: Fifty patients scheduled for elective coronary artery surgery. INTERVENTIONS: The patients were randomly allocated to receive treatment for an SB (less than 60 BPM) with either transesophageal atrial pacing (TAP) or gallamine. MEASUREMENTS AND MAIN RESULTS: Heart rate, blood pressure, and systemic hemodynamics were measured. The electrocardiogram was monitored for rate, rhythm, and conduction abnormalities. Twenty-four of the 25 TAP patients could be paced at a rate of 70 BPM after SB. Cardiac index increased from 1.90 to 2.56 L/min/m2. In the gallamine group, heart rate was increased from 50 to 66 BPM, but cardiac index only increased to 2.2 L/min/m2, and 2 patients developed nodal rhythms. Eight of these patients had peak heart rates over 80 BPM, and two were over 90 BPM. CONCLUSIONS: The ability to reliably and precisely control heart rate was superior with TAP compared with intermittent bolus dosing with gallamine.

    Transesophageal atrial pacing in anesthetized patients with coronary artery disease. Hemodynamic benefits versus risk of myocardial ischemia. Hogue CW; Davila-Roman VG; Pond C; Hauptmann E; Braby D; Lappas DG. Washington University School of Medicine. Anesthesiology (United States), Jul 1996, 85(1) p69-76. BACKGROUND: Transesophageal atrial pacing (TEAP) provides prompt and precise control of heart rate and improves hemodynamics in anesthetized patients with bradycardia and hypotension. The authors' purpose in this study was to examine the hemodynamic benefits of TEAP versus the risk of myocardial ischemia in patients about to undergo coronary artery bypass surgery. METHODS: Hemodynamics, ventricular filling pressures, mixed venous oxygen saturation, and end-diastolic, end-systolic, and fractional area change of the left ventricle, determined by transesophageal echocardiography (TEE), were measured after anesthesia induction with 30 micrograms/kg fentanyl and at incremental TEAP rates of 65, 70, 80, and 90 beats/min (bpm) in 40 adult patients. Monitoring for myocardial ischemia was accomplished with 12-lead electrocardiograms and biplane TEE assessment of left ventricular regional wall motion. Hemodynamics, electrocardiograms, and TEE measurements at each TEAP rate were compared with baseline awake measurements (except TEE) and with measurements obtained after anesthesia induction before TEAP. RESULTS: Sinus bradycardia occurred in 15 patients after anesthesia induction and was associated with a hypotensive response and a decrease in cardiac output in 10 patients. In these patients, TEAP restored diastolic blood pressure and cardiac output to baseline values at TEAP rates of 65 and 80 bpm, respectively. Stroke volume was similar to baseline measurements after anesthesia induction and at TEAP rates of 65, 70, and 80 bpm, but was significantly reduced from baseline at TEAP 90 bpm. Myocardial ischemia was detected in 7 and 5 patients at a TEAP rate of 80 and 90 bpm, respectively. CONCLUSIONS: Control of heart rate with TEAP restores intraoperative hemodynamics to baseline in patients in whom bradycardia and a hypotensive response develop before coronary artery bypass surgery. When using TEAP for patients with severe coronary artery disease, these results support using the lowest TEAP rate titrated to achieve optimal hemodynamics, while closely monitoring for myocardial ischemia, especially at TEAP rates 80 bpm.

    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, Arzco Medical Electronics) 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 (Arzco Medical Electronics). 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.

    Use of temporary atrial pacing in management of patients after cardiac surgery. Takeda M, Furuse A, Kotsuka Y. University of Tokyo, Japan. Cardiovasc Surg 4(5):623-7, 1996. The authors' clinical experience with temporary atrial pacing to evaluate its use in the management of patients after cardiac surgery was reviewed. A total of 339 patients undergoing cardiac surgery were studied with regard to postoperative pacing therapy. Postoperative pacing was performed in 186 of 339 patients to treat supraventricular bradycardia or tachyarrhythmias. Rapid atrial pacing was performed to interrupt re-entrant supraventricular tachyarrhythmias. In bradycardic patients, haemodynamics could be improved as the result of significant increase of blood pressure and oxygen saturation in the pulmonary artery (SVO2) caused by atrial pacing. Premature beats could be suppressed in 63% and supraventricular tachyarrhythmias could be interrupted in 66% of the patients only by atrial pacing. Temporary atrial pacing is safe, rapid and effective as the treatment of choice; it is believed that the technique should be applied in preference to pharmacological treatment in the management of patients after cardiac surgery.

    Thresholds for transesophageal atrial pacing. Dick M 2d, Campbell RM, Jenkins JM. Cathet Cardiovasc Diagn 1984; 10(5):507-13 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 reentrant supraventricular tachycardia. Depending on the patients' age and size several electrode catheters were used. The protocol called for 1-msec step-wise increments in pulse width. At each pulse width the current was increased by 1 mamp until capture was achieved. The mean minimal pulse width and mean minimal current required for capture were 5.8 msec and 13.6 mamp, respectively. Atrial capture was achieved in 75% of attempts at a pulse width and current equal to or less than 6.5 msec and 17.5 mamp, respectively. No correlation between current and pulse width on the one hand and age, height, weight, or body surface area on the other was 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 the subject's age or size.

    Use of the pill electrode for transesophageal atrial pacing. Jenkins JM, Dick M, Collins S, O'Neill W, Campbell RM, Wilber DJ. Pacing Clin Electrophysiol 1985 Jul;8(4):512-27. The pill electrode, which was developed for esophageal electrocardiography, has found application in transesophageal atrial pacing during procedures such as conversion of tachycardia, electrophysiologic measurement, and acceleration of heart rate to produce stress during cardiac imaging studies. This paper presents theoretical studies that examine the relationship of interelectrode distance, current level, and pulse duration to the achievement of successful capture. Theoretical results agree with our clinical findings, i.e., current levels of 25 mA are effective to sustain capture; increased pulse duration reduces current requirements; and close bipolar spacing combines efficacy with safety. Results of animal studies performed to assess the extent of esophageal burn injury reveal that current levels in excess of 75 mA are required to produce lesions in short-term (under 30 minutes) pacing, and greater than 60 mA in long-term (4 hours) pacing. These results are based on experiments using a pulse duration of 2 ms, and the current levels that produce injury will be considerably lower if longer pulse durations are used. Typical current levels and pulse durations for successful capture are presented for 46 subjects in several new clinical applications. Termination of tachycardia, basic electrophysiologic measurements, and controlled acceleration of heart rate can be performed noninvasively with this technique.

    Transesophageal atrial pacing for treatment of acute sinus bradycardia. Iliou MC, Lavergne T, Bendada A, LeHeuzey JY, Guize L.  RBM 16(3/4): 138-141, 1994. Transesophageal atrial pacing (TAP) is a non-invasive technique commonly used for reduction of supraventricular tachycardias. Few cases of long-term TAP have been reported in patients with general anesthesia. The present study was conducted for assessing the feasibility and tolerance of long-term TAP in non-sedated patients. Ten symptomatic patients (mean age 71.4 years, range 58-87) with sinus bradycardia were paced in esophagus using a 20-25 ms duration pulse with voltage ranging from 12-20 V at a rate > 60 BPM. No patient had significant impairment of anterograde AV conduction. Sinus bradycardia was caused by drugs in 8 and/or hyperkalemia in 2 patients. TAP was maintained until sinus rate exceeded pacing rate during mean time of 22.8 hours (1.5 - 98 hrs). Four patients had permament pacemaker implanted. Esophageal fibroscopy was performed in 4 patients; no lesions were found. Tolerance was assessed using an auto-evaluation scale. Two patients were asymptomatic, 5 had a slight discomfort, and 3 had moderate chest pain which did not require interruption of TAP. Alteration of the anodal electrode was noted when TAP exceeded 24 hours. In conclusion, TAP is an efficient and safe technique for prolonged atrial pacing in non-sedated patients with transient symptomatic sinus bradycardia. 

    A comparison of transesophageal and transvenous pacing. Rotter SJ, Koehler, D. Mass Genl Hospital, Boston. Anesth Analg 80: SCA78, 1995. Introduction: Transvenous or endocardial pacing has been considered a standard technique for treating intra-operative bradycardia in cardiac patients. Recently, transesophageal atrial pacing (TAP) has become available with a modified transesophageal stethoscope. Because TAP is left atrial pacing and transvenous is right atrial pacing, we compared the efficacy and hemodynamics of each. We postulated that the time required to institute esophageal pacing is shorter than the time to institute transvenous pacing, even in those patients in whom an appropriately placed A-V paceport PA line is already in place. Methods: Twenty consecutive patients undergoing cardiac surgery were enrolled if they had a resting heart rate < 60 BPM. An A-V paceport PA line without the atrial pacing wire was placed in each patient. After induction with fentanyl and vecuronium, non-paced hemodynamics were recorded using pulse, BP, cardiac output, PA pressure, pcwp and cvp. Before incision, the patient was paced consecutively either transvenously or with TAP in random order. Each patient served as his/her own control. We recorded the time from when pacing was desired to the initiation of pacing. We also noted thresholds, depths to capture, efficacy/complications and hemodynamics. Results:

    Sinus: Endocardial: Esophageal:
    Pulse rate   (BPM) 50.2 +/- 6.5*  74.8 +/- 0.4 74.8 +/ -0.4
    SBP (mmHg) 112.3 +/- 14.4* 127.8 +/- 16.7 128.4 +/- 16.0
    DPB (mmHg) 55.5 +/- 8.1* 67.5 +/- 10.1 67.7 +/- 10.0
    Mean BP (mmHg) 74.7 +/- 9.5* 89.3 +/- 12.5 89.2 +/- 11.4
    CO (l/min) 4.0 +/- 1.2* 5.0 +/- 1.5 5.1 +/- 1.7
    Time (sec) ----------------- 129.7 +/- 31.2 73.3 +/- 62.2**
    Threshold (mA) ----------------- 4.6 +/- 2.5 12.1 +/- 3.7**

    * p < .001 sinus vs. endocardial and esophageal pacing,    ** p < .001 esophageal vs. endocardial pacing
    There were no significant complications with either pacing technique and efficacy was 100% with both methods. It was impossible to obtain a wedge pressure and pace via the PA catheter simultaneously due to heart or patient size. Discussion: Although endocardial is via the right atrium and esophageal pacing is via the left atrium, we found no significant hemodynamic differences between them. TAP is quicker to obtain with no apparent complications. In these patients, intra-operative bradycardia and hypotension can be improved with the institution of temporary pacing. The data may be reasonably extrapolated to any patient with hemodynamically significant bradycardia and it appears that TAP may be a suitable alternative to the patient who needs temporary cardiac pacing.

    Hemodynamic benefit of atrial pacing in right ventricular myocardial infarction. Topol EJ, Goldschlager N, Ports TA, Dicarlo LA jr, Schiller NB, Botvinick EH, Chatterjee K. Ann Intern Med 96(5):594-7, 1982. Right ventricular and inferior-posterior myocardial infarctions in four patients were complicated by low-output syndrome unresponsive to increasing intravascular volume. Ventricular pacing was started because of bradyarrhythmias, but failed to increase cardiac output; atrial pacing at identical rates resulted in dramatic increases in cardiac output. The importance of atrial contribution to ventricular function, as well as the role of the pericardium in this clinical setting, are discussed. In treating right ventricular myocardial infarction, atrial or atrioventricular sequential cardiac pacing may be preferable to ventricular pacing.

    Atrial esophageal pacing in patients undergoing coronary artery bypass grafting (CABG): effect of previous cardiac operations and body surface area. Buchanan D, Clements F, Reves JG, Hochman H, Kates R. Duke Univ Medical Center. Anesthesiology 69:595-598, 1988. Correlates of transesophageal atrial pacing thresholds and hemodynamic during TAP were measured in 21 patients during CABG surgery (11 patients during their first and 10 patients for the second surgery). Patient weight, body surface area, heart rate, cardiac index, systemic and pulmonary blood pressures and system vascular resistance were measured. Results: No significant differences in pacing threshold were found between the 2 patient groups (initial vs. second CABG) or between patient who had suffered a previous myocardial infarction and those who had not. Pacing threshold (mA) was positively correlated with body surface area, with an (approximated) linear regression equation of Threshold = -22 + 22 BSA. Eleven of 21 patients became bradycardic after tracheal intubation; their hemodynamic measurements before and during pacing were:

    * p < .05   vs. before pacing Before Pacing During Pacing
    Heart Rate (BPM) 50 +/- 7 82 +/- 8 *
    Cardiac Index (l/min)/m2 2.0 +/- 0.4 2.8 +/- 0.6*
    Systemic Blood Pressure (systolic, mmHG) 111 +/- 16 123 +/- 22*
    Pulmonary Blood Pressure (systolic, mmHG) 25 +/- 8 27 +/-8
    Systemic Vascular Resistance (dynes sec/ cm3) 1258 +/- 318 1051 +/- 269*

    No dysrhythmia or signs of myocardial ischemia during pacing were noted. Conclusion: Body size (but not previous cardiac operative status or prior myocardial infarction) influences the current threshold for transesophageal pacing. Increased systemic blood pressure and cardiac output resulted during (chronotropic) pacing for intraoperative bradycardia. (CardioCommand abstract)

    Transesophageal atrial pacing for the treatment of dysrhythmias in pediatric surgical patients. Greeley WJ; Reves JG. Duke University Med Ctr. Anesthesiology, Feb 1988, 68(2) p282-5. Cardiac dysrhythmias occur frequently in pediatric patients with congenital heart defects during general anesthesia and may cause hemodynamic instability. Urgent treatment of hemodynamically significant dysrhythmias in children during surgery heretofore has required antiarrhythmic therapy where efficacy is unpredictable. Alternatively, emergency transvenous cardiac pacing, which is highly invasive and technically difficult, is possible. We report 2 cases where transesophageal atrial pacing was successfully performed in pediatric surgical patients in the treatment of hemodynamically signficant dysrhythmias during general anesthesia.

    Transesophageal atrial pacing: importance of the atrial-esophageal relationship. Crawford TM; Dick M 2d; Bank E; Jenkins JM Med Instrum (United States), Jan-Feb 1986, 20(1) p40-4. To determine the thresholds for transesophageal atrial capture, as well as factors that might influence the thresholds, the authors measured the minimal current and pulse duration required to pace the atrium through transesophageal bipolar lead systems in 32 patients during 42 trials. Mathematical modeling suggested that the current density at the posterior atrial wall was dependent upon the current delivered, the electrode distance, and, most importantly, the esophageal-atrial geometry, expressed as the distance from the esophagus to the excitable tissue. To examine this esophageal-atrial distance, 17 different patients, aged 11 months to 44 years, were studied concurrently with either computerized tomography or magnetic resonance imaging of the chest. The thresholds needed to capture the atrium from the esophagus were 13.2 +/- 3.7 mA at a pulse duration of 5.8 +/- 3.1 msec. Further, the data demonstrated that the threshold for transesophageal atrial pacing was poorly related to the patient's age or size. The fit between these data and the mathematical model suggested that the distance between the left atrial posterior wall and the esophagus was approximately 5-6 mm. Likewise, the minimal esophageal-atrial distance as measured by the two imaging techniques was equal to or less than 3.3 mm. These observations suggest that the distance (anterior-posterior dimension) between left atrial posterior wall and the esophagus is small and remains constant despite obvious changes in somatic and linear growth.

    Optimal mode of transesophageal atrial pacing. Nishimura M, Katoh T, Hanai S, Watanabe Y. Am J Cardiol 1986 Apr 1;57(10):791-6. The optimal mode of transesophageal atrial pacing was determined by clinical electrophysiologic studies in 15 healthy adult volunteers. The point at which the unipolar atrial electrogram was biphasic and largest in amplitude (35.4 +/- 1.6 cm from the incisors) was considered the best stimulation site for atrial pacing. The stimulation threshold on bipolar pacing (using the proximal pole as cathode and the distal pole as anode) at this site was 27 +/- 7 mA, which was significantly lower (p less than 0.001, n = 10) than that on unipolar cathodal stimulation (41 +/- 8 mA). Although the stimulation threshold tended to be higher with a No. 10Fr electrode catheter (30 +/- 5 mA) than with a No. 6Fr catheter (27 +/- 7 mA), the difference was statistically insignificant (n = 9). When the interpolar distance in bipolar stimulation was varied in 5 steps from 12 to 80 mm, the threshold was lowest at the distance of 24 mm. Of the 10 pulse durations tested, ranging from 0.25 to 128 ms, 8 ms appeared most desirable in minimizing the total amount of current and chest discomfort accompanying the pacing. With the optimal site, interpolar distance and pulse duration, transesophageal atrial pacing was successfully performed in all patients, without producing significant complications such as chest pain. Transesophageal atrial pacing is noninvasive, technically simple and efficient, and may be valuable in the diagnosis and treatment of various cardiac arrhythmias.

    Transesophageal pacing for bradycardia. Backofen JE; Schauble JF; Rogers MC. Dept of Anesthesiology and Critical Care, John Hopkins Univ. Anesthesiology 1984, 61(6) p777-9. Sinus bradycardia during anesthesia is often acute in onset, may produce hypotension, and may lead to more serious dysrhythmias. The response of bradycardia to pharmacoligical interventions is unpredictable, and therefore cardiac pacing provides a more precise and effective treatment. We report our experience with 37 surgical patients with intact AV conduction who were successfully treated by transesophageal atrial pacing for hemodynamically significant bradycardias. (CardioCommand abstract)

    Successful emergency traneoesophageal cardiac pacing with subsequent endoscopy. Shaw RJ, Berman LH, Hinton, JM. Br Med J 284:309, 1982. A 71 year-old woman admitted with syncope, a pulse rate of 20 BPM and complete AV block fell unconscious while a transvenous pacing lead was being prepared. A bipolar oesophageal electrode was inserted nasally to its full length and gradually withdrawn until ventricular capture occurred. The entire procedure was completed in less than 30 secs. Upon regaining consciousness, the patient complained of chest pain associated with the pacing. Transvenous pacing was established within 30 minutes and transesophageal pacing then discontinued. Esophagoscophy performed 45 hours later found no evidence of erythema, erosions or ulceration to the mucosa. (CardioCommand abstract)

    Experience in using transesophageal electrocardiostimulation in emergency heart rhythm disorders. Egorov DF; Sapozhnikov IR; Vygovskii AB; Domashenko AA; Zhukov OS. Ter Arkh (USSR), 1987, 59(10) p51-3. The paper is concerned with the results and analysis of transesophageal electrocardiostimulation in 383 patients before and in hospital over 6 years for urgent therapy of brady- and tachyarrhythmias. The method was assessed using a simple, recoverable and effective first aid element in combined resuscitation measures, in therapy of paroxysms of supraventricular tachycardia, in patients with the sinoatrial node weakness syndrome during cardioversion and narcosis, in primary and repeated pacemaker implantations, in acute myocardial infarctions complicated by bradyarrhythmias. Transesophageal electrocardiostimulation in urgent therapy of bradyarrhythmias, the sinoatrial node weakness syndrome, disorders of permanent electrocardiostimulation with fits of Morgagni-Adams-Stokes syndrome is an uncomplicated method of choice and a stage before temporary endocardial and permanent electrocardiostimulation.

    Improved transesophageal recording and stimulation utilizing a new quadripolar lead configuration. Kerr CR, Chung DC, Cooper J. Pacing Clin Electrophysiol 1986 Sep;9(5):644-51. Transesophageal pacing and recording are valuable techniques in the diagnosis and treatment of patients with arrhythmias. Bipolar pacing with bipolar catheters has been effective, but recording from the same electrodes is not possible during and immediately following pacing. We utilized a fine no. 4 French quadripolar catheter in 21 subjects to stimulate the atrium and record atrial electrical activity simultaneously. Pacing characteristics were equivalent to previously used bipolar catheters and recording was markedly enhanced. Bipolar atrial electrograms could be recorded either during pacing or at the first atrial depolarization following pacing in all patients. Thus, this quadripolar pacing lead improves the diagnostic value of studies involving transesophageal atrial pacing and recording.

    Transesophageal atrial stimulation: a technic with the pentapolar catheter electrode. Seminario Origgi MA, Alves de Godoy R. Departamento de Clinica Medica, Universidad de Sao Paulo, Brasil. Arch Inst Cardiol Mex 1992 Nov-Dec;62(6):547-55. The objective of the present study was to employ a transesophageal atrial pacing (TAP) technique that would permit the use of the lowest possible currents for consistent atrial capture (CAC) and a more accurate recording system. An electrode catheter containing five poles (E1 to E5) spaced 22 mm apart was constructed, with pole E1 being the most cranial one. The catheter was introduced nasally into the esophagus of eleven adult healthy volunteers, and five unipolar intraesophageal leads were recorded and analyzed until the tracings obtained with E2, E3 and E4 showed P waves of the highest potentials, when the catheter was fixed in place. An electric generator specially constructed for TAP was used. CAC was attempted with each of the 20 stimulating bipoles formed by the permutations of the five poles of the fixed catheter. The least voltage needed for CAC in each individual was always detected in at least one of the six stimulating bipoles formed by the permutations involving poles E2, E3 and E4. Thus, in the population studied as a whole, the minimum voltage range needed to obtain TAP was between 5 and 15 V (mean 11.2 +/- 3.0 V), which was tolerated quite well by the individuals. Pulse durations of more than 10 ms did not lead to use of significantly lower voltages for CAC. Six simultaneous tracings were used during and after TAP, and at least one of them recorded intraesophageal or esophago-thoracic bipolar leads.

    Balloon electrode catheter for transesophageal atrial pacing and transesophageal ECG recording. Heinke M, Volkmann H. Department of Internal Medicine, Jena-Lobeda, Germany. Pacing Clin Electrophysiol 1992 Nov;15(11 Pt 2):1953-6. A new balloon electrode catheter (10 French) with five or six balloon electrodes placed on the cardiac side was developed for transesophageal atrial pacing and bipolar ECG recording. The diameter of the hemispheric electrodes is 6 mm and the length of the esophageal balloon is 10 cm. The transesophageal atrial pacing threshold was measured with the balloon electrode catheter by transesophageal programmed atrial stimulation (TPS) (n = 54). At the onset of TPS, the feeling, capture (n = 54), and pain voltage threshold (n = 6) were measured by increasing the amplitude of the pacing voltage during high rate bipolar atrial pacing and bipolar atrial ECG recording. In 38 TPS, the capture threshold was lower than the feeling threshold (n = 28). In 16 TPS, the capture threshold was higher than the feeling threshold. In conclusion, painless atrial pacing and excellent ECG recording can be achieved with a multipolar esophageal balloon electrode catheter with a low pacing voltage amplitude and a high P wave amplitude.

    Transesophageal atrial pacing--stimulation and discomfort thresholds: the role of electrode configuration and pulse width. Res JC, Van Woersem RJ, Dekker E, Dunning AJ.University of Amsterdam, The Netherlands.Pacing Clin Electrophysiol 1991 Sep;14(9):1359-66. A balloon catheter with six electrodes has been developed for transesophageal atrial stimulation of the human heart. Introduction is easy and its positioning is simple with the help of six unipolar atrial electrograms. In a group of 20 healthy volunteers, stimulation and discomfort thresholds (intolerable discomfort) were measured for three levels of pulse widths (12, 16, and 20 msec) and for five electrode configurations. Stimulation thresholds were below discomfort thresholds in each case. The stimulation threshold depended on pulse width and not on electrode configuration. The discomfort threshold, however, depended on the electrode configuration and not on the pulse width. A moderate but potentially important increase of the ratio between stimulation threshold and discomfort threshold could be achieved by combining a long pulse width (20 msec) and avoiding the largest distance between the active (cathode) and the passive (anode) electrode. Transesophageal atrial stimulation promises to be a practical noninvasive tool for the termination of regular supraventricular tachycardias, basal electrophysiological studies, and controlled acceleration of the heart rate in the study of myocardial ischemia.

    Electrode-myocardium distance in transesophageal atrial stimulation. Boden H, Paliege R, Klinik fur Innere Medizin, Suhl. Gesamte Inn Med 1990 Nov 1;45(21):643-6  In 9 voluntary test persons with a sound heart, comparative examinations were carried out to discover the optimum depth of insertion by unipolar and bipolar determination of the absolute threshold and transoesophageal derivation as well as the correlation of the optimum depth of insertion with external measurements of the body. The methods mentioned to ascertain the optimum depth of insertion are equivalent concerning the bipolar arrangement of the electrodes in the oesophagus. The average effective depth of insertion can simplified be defined. A correlation of the average effective depth of insertion concerning external measurements of the body could not be found, so that the conscientious discovering of the optimum depth of insertion is a necessity for every patient. The average value found could attain an orientating importance with the primary placing of the probe concerning the average effective depth of insertion of 37 cm.

    Usefulness of transesophageal atrial pacing in hyperkalemia-induced impulse formation and conduction disturbances. Di Biase M; Rizzo U; Minafra F; Tritto M; Favale S; Rizzon P. University of Bari, Italy. Int J Cardiol, Nov 1989, 25(2) p213-8. This report describes the usefulness of transesophageal atrial pacing in the treatment of five patients with hyperkalemia-induced bradycardias. Three patients had marked sinus bradycardia while the other two had a regular rhythm with QRS of left bundle branch block morphology, with no P waves visible on the surface electrocardiogram. Four patients were in chronic hemodialysis three times a week, and one had severe post-traumatic hemorrhage. In three patients, hyperkalemia had been precipitated by food intoxication. In one case the cause was unknown while, in the last case, hyperkalemia was due to rapid infusion of stored blood and solutions containing high concentrations of potassium. Transesophageal atrial pacing was performed in all cases utilizing a bipolar catheter introduced into the esophagus and a constant current generator delivering square wave pulses of 10 msec duration and 19-28 mA intensity. Atrial capture, followed by impulse conduction to the ventricles, was constant in all cases, being performed for between 15 and 35 minutes until a normal sinus rhythm was restored. The procedure was well tolerated. The advantages of this procedure as opposed to invasive ventricular pacing are discussed.

    Positioning the pacing esophageal stethoscope for transesophageal atrial pacing without P-wave recording: implications for transesophageal ventricular pacing. Roth JV; Brody JD; Denham EJ (Albert Einstein Med Ctr, Philadelphia) Anesth Analg 1996 Jul;83(1):48-54 This study determined guidelines for positioning a new pacing esophageal stethoscope (PES) used for transesophageal atrial pacing (TEAP) without having to record esophageal P waves. In 44 patients with heights ranging from 142 cm (4'8") to 193 cm (6'4"), the PES was inserted to a depth of insertion (DOI) of 43 cm. As the PES was withdrawn, TEAP thresholds were determined at every DOI in 1-cm intervals between 43 and 25 cm DOI inclusive. TEAP was accomplished in all 44 patients. The minimum TEAP threshold (mean +/- SD 10.8 +/- 4.0 mA) was or = 17 mA in 43 of 44 patients (98%). Except for one patient, TEAP could be accomplished over a 9- to 19-cm (mean +/- SD, 13.7 +/- 2.8 cm) wide range of DOI. Unintentional transesophageal ventricular pacing (TEVP) occurred in 15 of 44 (34%) of patients. TEVP occurred over a 1- to 7-cm (mean +/- SD, 3.7 +/- 1.7 cm) wide range of DOI; the minimum TEVP threshold averaged 30.4 +/- 6.4 mA. TEAP was consistently accomplished at DOIs more proximal than where TEVP could occur and with lower currents than that required for TEVP. An insertion depth, in centimeters, equal to half of the patient's height, in inches, produced successful TEAP in all 44 patients; the minimum TEAP threshold occurred on average at a DOI 2.6 cm more proximal. Asynchronous TEVP can be avoided by using lower currents at shallow DOIs.

    The effect of nasal or oral gastric tubes on transesophageal atrial pacing thresholds [see comments]. Roth JV; Huertas R; Sagel JS. Albert Einstein Medical Center. Anesth Analg 1996 Feb; 82(2):429. This study was performed to evaluate whether the presence of either nasal or oral gastric tubes (GTs) would affect the ability to accomplish transesophageal atrial pacing (TAP). After endotracheal intubation, pacing esophageal stethoscopes were placed and the TAP thresholds were measured in 20 patients. With the PES fixed in position, GTs were inserted and pacing thresholds were remeasured. TAP was accomplished in all patients pre- and postinsertion. The mean +/- SD, range, and median TAP thresholds (mA) were 13.7 +/- 5.8, 7-25, and 12 preinsertion and 13.9 +/- 5.2, 5.5-25, and 13 postinsertion. The preinsertion-postinsertion differences ranged from -6 to 5 mA with a mean of the difference of -0.2 mA (95% confidence interval, -1.61-1.21 mA). No significant difference between the pre- and postinsertion groups was detected by the paired t-test, P = 0.77. In summary, the presence of GTs does not significantly affect TAP thresholds. Attempts to achieve TAP are expected to be successful in patients with either a nasal or oral GT in place.

    Esophageal balloon electrode catheter for transthoracic recording of His-bundle potential with transesophageal atrial pacing. Heinke M, Kuhnert H, Volkmann H, Butkewitz F, Muller S. University Hospital of Internal Medicine III, Division of Cardiology, Jena, Germany. Pacing Clin Electrophysiol 1994 Nov;17(11 Pt 2):2125-8. To evaluate the influence of transesophageal atrial pacing of the transthoracic His potential identification, we combined signal-averaged ECG with transesophageal atrial pacing with low threshold for pacing averaging ECG recording. A tripolar 10 French esophageal balloon electrode catheter, with one cylindrical electrode on the tip of the catheter and two balloon electrodes on the cardiac side of the catheter, used in 53 patients, allowed a painless transesophageal atrial pacing and a high signal to noise distance in the signal-averaged ECG. Transesophageal atrial pacing allowed in 37 of 53 patients an identification of His potential by increasing the distance between the end of the atrial potential and the onset of the His potential in the pacing averaging ECG. The esophageal balloon electrode catheter allowed a painless transesophageal atrial pacing with low threshold for atrial capture during a long pacing time and a high signal to noise distance in the pacing averaging ECG. The increasing of the heart rate with transesophageal atrial pacing allowed the transthoracic identification of the His potential in the pacing averaging ECG.

    Emergency 12-hour transesophageal stimulation in a 21-month-old infant. Paul T, Luhmer I, Wilken M, Kallfelz HC.Hannover. Anaesthesist 1993 Aug;42(8):564-6. 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. 

    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 hertofore 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.

    Long-term left atrial stimulation by transesophageal approach in complicated biventricular infarction. Khalife K, Boursier M, Donetti J, Maurier F, Aliot E. Service de cardiologie A et de soins intensifs, hopital Notre Dame de Bon Secours, CHR de Metz. Arch Mal Coeur Vaiss 1991 Feb;84(2):253-5. The authors report the value of transoesophageal pacing in a 50 year old patient with acute biventricular infarction and cardiogenic shock who developed sinus node dysfunction, junctional rhythm and retrograde atrial activation. This mode of pacing was used permanently for a 48 hour period at a rate of 80/min (atrial capture with a pacing potential of 12 volts and an impulse duration of 12 ms). The clinical results were spectacular and the procedure was well tolerated. This technique can be instituted at the bedside and should be considered in selected cases of sinus node dysfunction when endocavitary pacing is not possible.

    Transesophageal ventricular pacing in anesthetized adults. Atlee JL, Bilof R. Anesthesiology 79(3A), 1983.

    Transesophageal pacing. Andersen HR; Pless P. Pacing Clin Electrophysiol (United States), Jul 1983, 6(4) p674-9. A new lead-electrode for transesophageal pacing of the human heart has been developed. The heart can be paced from the esophagus using currents of the same intensity as those for temporary pacing electrodes. The lead allows the electrodes to be positioned properly in the esophagus with a gastric balloon without use of additional equipment. Noninvasive atrial or ventricular pacing can thus be established quickly, even by non-specialized physicians. The method has been tested on a group of 13 healthy volunteers. Both atrial and ventricular pacing were performed without discomfort. The method opens new diagnostic and therapeutic possibilities with transesophageal pacing techniques.

    A method of esophageal electrogram recording for diagnostic atrial and ventricular pacing. Prochaczek F, Jerzy G, Stopczyk MJ. Silesian Medical Academy, Reymonta, Poland. Pacing Clin Electrophysiol 1990 Sep;13(9):1136-41. This study evaluates improvement of the electrogram sensed via an esophageal catheter with the sensing electrode adjacent to the stimulating electrode with and without a specialized artifact suppression system. In 100 patients (65 men and 35 women) aged 16-60 years (mean 48 years), esophageal recordings of left atrial activity were obtained during simultaneous transesophageal atrial pacing. Transesophageal ventricular pacing was performed in an additional 34 patients. Without the suppression system, ventricular paced activity, recorded from the esophagus, was not suitable for interpretation. About 10% of the atrial electrogram response could be recorded and evaluated during atrial pacing. With the stimulus artifact suppression system, interpretable recordings were obtained 100% of the time during atrial and ventricular recordings. The method described allows use of transesophageal diagnostic testing where previously only the intracardiac route was possible.

    Use of the gastro-oesophageal route for the rapid establishment of ventricular pacing. McEneaney DJ, Cochrane DJ, Adgey AA. Regional Medical Cardiology Centre, Royal Victoria Hospital, Belfast, UK. Int J Cardiol 1994 Oct;46(3):275-8. A novel approach to emergency ventricular pacing has been developed using a gastro-esophageal electrode. The polythene electrode was passed into the stomach, after which the electrode tip was positioned in the gastric fundus. Ventricular pacing was performed using a cathode mounted on the electrode tip; the indifferent electrode (anode) was either a chest pad or a proximal ring electrode. Ventricular capture was easily achieved in three emergency cases of severe bradyarrhythmia.

    A gastroesophageal electrode for atrial and ventricular pacing. McEneaney DJ, Cochrane DJ, Anderson JA, Adgey AA. Pacing Clin Electrophysiol 1997 Jul;20(7):1815-25. Temporary transvenous cardiac pacing requires technical expertise and access to fluoroscopy. We have developed a gastroesophageal electrode capable of atrial and ventricular pacing. The flexible polythene gastroesophageal electrode is passed into the stomach under light sedation. Five ring electrodes, now positioned in the lower esophagus, are used for atrial pacing. A point source (cathode) on the distal tip of the electrode, now positioned in the gastric fundus, is used for ventricular pacing. Two configurations of atrial and ventricular pacing were compared: unipolar and bipolar. During unipolar ventricular pacing the indifferent electrode (anode) was a high impedance chest pad. For bipolar ventricular pacing the indifferent electrode was a ring electrodes placed 2 cm proximal to the tip. Unipolar atrial pacing was performed with 1 of 5 proximal ring electrodes acting as cathode ("cathodic") or as anode ("anodic") in conjunction with a chest pad. Bipolar atrial pacing was performed using combinations of 2 of 5 ring electrodes. Atrial capture was obtained in all 55 subjects attempted. When all electrode combinations were compared, atrial capture was significantly more frequent using the bipolar approach (153/210 bipolar, 65/210 unipolar; t = 7.37, P < 0.001). For unipolar atrial pacing, cathodic stimulation (from esophagus) was more successful than anodic stimulation (cathodic 62/105, anodic 20/105; t = 5.81, P < 0.001). In 43 subjects attempted unipolar ventricular pacing resulted in a higher frequency of capture than the bipolar approach (unipolar 41/43 (95.3%), bipolar 19/43 (44.2%); P < 0.001). In conclusion, atrial pacing was optimal using pairs of ring electrodes ("bipolar") while ventricular pacing was optimal using the distal electrode tip (cathode) in conjunction with a chest pad electrode ("unipolar"). This gastroesophageal electrode may be useful in the emergency management of acute bradyarrhythmias and for elective electrophysiological studies.

    Ventricular pacing with a novel gastroesophageal electrode: a comparison with external pacing. McEneaney DJ, Cochrane DJ, Anderson JA, Adgey AA.  Belfast, Northern Ireland. Am Heart J 1997 Jun;133(6):674-80. Temporary endocardial pacing is a technically demanding invasive procedure requiring sterile precautions and access to fluoroscopy. External (transcutaneous) pacing requires high current for capture and is poorly tolerated in the conscious patient. An esothoracic pacing system has been developed capable of reliable ventricular capture. The flexible gastroesophageal electrode is passed into the stomach. The distal 6 cm is angled to 90 degrees with an internal pulley system, positioning the tip of the gastroesophageal electrode in the fundus of the stomach. Ventricular pacing is performed with a spherical electrode (cathode) mounted on the gastroesophageal electrode tip in conjunction with a chest pad (anode) positioned medial to the cardiac apex. Of 91 subjects in which esothoracic pacing was attempted, 86 (94.5%) demonstrated successful ventricular capture at the maximum pulse duration used (40 msec). Threshold current for ventricular capture ranged from 22.5 +/- 8.1 mA at a pulse duration of 40 msec to 29.9 +/- 8.6 mA at a pulse duration of 10 msec. Esothoracic pacing was compared with external pacing in a subgroup (n = 30) of patients. Ventricular capture with the gastroesophageal electrode was more common when compared with the external approach (27 [90%] of 30 vs 13 [43.3%] of 30, p < 0.001). In those subjects in whom ventricular capture was obtained with both methods, threshold current for capture was significantly lower with the esothoracic approach. This gastroesophageal electrode may be useful in the emergency management of acute bradyarrhythmias.

    An esophageal and gastric approach to ventricular pacing. Cochrane DJ, McEneaney DJ, Dempsey GJ, Anderson JM, Adgey AA. Pacing Clin Electrophysiol 1995 Jan;18(1 Pt 1):28-33. Using a unipolar esothoracic pacing system (where current passes from a point source positioned in the distal esophagus to a chest wall pad) and pulse duration of 50 msec, satisfactory 1:1 ventricular capture was obtained in 57 (86%) of 66 patients, with a mean threshold current of 27.7 mA at an optimal depth of 40.3 cm from the lower lip. When the unipolar esothoracic and bipolar transesophageal ventricular pacing systems were compared, the bipolar system was associated with a lower success rate and higher threshold current. When unipolar esothoracic pacing and gastrothoracic pacing (where current passes from a point source positioned in the stomach to a chest wall pad) were compared in 23 patients with bradyarrhythmia, ventricular capture was achieved using gastrothoracic pacing in 22 patients (96%) and esothoracic pacing in 21 (91%): gastrothoracic pacing required less current (16.0 mA +/- SD 7.2 vs 25.8 mA +/- SD 8.6). Optimal ventricular capture occurred using a unipolar gastrothoracic pacing electrode inserted to an average depth of 44.3 cm together with a high impedance chest pad (250 omega) placed in the fourth interspace at the left sternal edge, with 50-msec current pulses and a mean threshold of 16.0 mA. Thus, using a gastroesophageal electrode system, ventricular pacing can be achieved successfully, and the availability of such a system could play a major role in resuscitation of patients from severe bradyarrhythmias.

    Temporary cardiac pacing from the oesophagus. Cooper DN. Postgrad Med J 58: 45-46, 1982. Case studies are reported in which temporary cardiac pacing was performed in 2 patients for 72 hours and 90 mins using an oesophageal electrode.

    Clinical applications of external pacing: a renaissance? Luck JC, Markel ML. Pennsylvania State University, Hershey. Pacing Clin Electrophysiol 1991 Aug;14(8):1299-316. It is nearly 40 years since the first reports of noninvasive external pacing for Stokes-Adams syncope. Despite the ease and safety, this method of pacing has yet to flourish despite a recent interest by several authors. At present, external pacing seems best suited for temporary pacing situations that arise as an emergency or for purely prophylactic indications. External pacing is the preferred method of pacing recommended in the advanced cardiac life support guidelines. However, most emergency room and prehospital cardiac arrest trials have not shown any significant benefit from early application of external pacing. The indications have been broadened to include symptomatic bradycardia and termination of some ventricular tachycardias. It may be useful for the termination of AV reciprocating tachycardia and AV nodal reentrant tachycardia. There is a vision that external pacing may be used for serial electrophysiological testing of antiarrhythmic agents. However, there is little data in this regard. More importantly, the external pacing thresholds must be reduced further to allow for sophisticated pacing protocols to be implemented. For practical purposes, external pacing does not capture the atrium. Since the left atrium is easily captured by esophageal pacing, it is likely that noninvasive external pacing will be combined with transesophageal pacing to perform noninvasive electrophysiological testing. The future for external pacing remains in limbo because of the discomfort associated with skeletal muscle contraction. If technical advances can reduce or eliminate this problem, then external pacing may find broader application for bradycardia and tachycardia.

    Method of transesophageal electrostimulation of the ventricles in clinical practice. Rimsha ED, Kirkutis AA. Kardiologiia 1984 Dec;24(12):22-7. Possibilities of improving the efficacy of the trans-esophageal ventricular electrostimulation were studied in 22 patients with pacemaker weakness, the Wolff-Parkinson-White syndrome, transverse block and other disorders of the rhythm and conductivity of the heart. It has been shown that the amplitude of impulses in trans-esophageal ventricular electrostimulation may be decreased on the average to 32.36 +/- 1.37 V with the help of a specially-designed electrode, the optimal positioning of its cathode contact in the esophagus and the lengthening of electrical impulses. Trans-esophageal electrostimulation of the ventricles broadens the possibilities of the noninvasive electrophysiological examination and the treatment of complicated disturbances of the cardiac rhythm and conductivity.

    The feasibility of gastrothoracic ventricular pacing during transesophageal echocardiography. Kitahata H, Tanaka K, Kimura H, Kawahito S, Oshita S. Department of Anesthesiology, Tokushima University School of Medicine. Anesth Analg 89(1):21-5, 1999. We evaluated whether ventricular pacing is possible using pacing electrodes attached to a transesophageal echocardiography (TEE) probe in 20 patients undergoing elective cardiovascular surgery. A bipolar pacing lead was fixed with silicone adhesive anteriorly to the TEE probe with the distal electrode 25 mm from the TEE probe tip. The TEE probe was positioned to obtain a transgastric short-axis view of the left ventricle. The distal or proximal electrode on the TEE probe was the cathode; the chest electrode placed at the V5 lead position was the anode. Gastrothoracic ventricular pacing (GVP) was performed at 100 bpm at 30- or 50-ms pulse duration. Transgastric ventricular pacing (TVP) was also attempted using both  TEE probe electrodes alternately as cathode/anode. Maximal generator output was 32 mA. GVP with the distal electrode as cathode was successful in 75% and 80% of patients at 30- and 50-ms pulse duration and 23.3+/-5.8 mA and 22.6+/-5.8 mA threshold currents, respectively. However, success rates (20% and 25%, respectively) were significantly lower with the proximal electrode as cathode using the same pulse durations and 14.4+/-5.3 mA and 16.7+/-6.8 mA threshold currents. The TVP success rate was significantly lower than that for GVP. With optimization, this system could become an available technique for intraoperative emergency ventricular pacing. IMPLICATIONS: Using an endocardial pacing lead attached to a transesophageal echocardiography probe, gastrothoracic ventricular pacing can be performed successfully without complications in 75%-80% of patients undergoing cardiovascular surgery. 

    Effectiveness of transoesophageal ventricular pacing in cardioresuscitation of adults. Sadowski Z, Szwed H. Inst of Cardiology, Warsaw. PACE 6: Abstract 488. The results of transesophageal ventricular pacing were analyzed in patients with complete atrioventricular block or sinus node disease. Ventricular pacing was performed using bipolar electrodes of our own design in 84 patients with cardiac arrest: 36 women and 48 men, aged 20 to 85 years (mean 66.8 years). Fifty-four patients (Group 1) had the electrodes inserted during resuscitation procedure after cardiac arrest while the remaining 30 patients at high risk of cardiac arrest (Group 2) had the electrodes introduced prophylactically pre-operatively. Pacing was initiated when pauses in the ventricular rhythm appeared and was effective in 48 of 54 pts in Group 1 (88.9%) and in 27 of 30 pts in Group 2 (90%). Patients were paced for 2 to 180 minutes.

    Transesophageal Cardiac Pacing. Burack B, Furman S. Am J Cardiol 23: 469-472, 1969. Successful fixed rate pacing in a 65 year old female patient in cardiac arrest was accomplished via the esophagus for 36 hours, followed by an additional 24 hours of demand pacing. Esophageal pacing was attempted only after several failed attempts to pass a flexible catheter into the right ventricle. No evidence of burn damage to the esophagus. Transesophageal cardiac pacing may be a simple, effective and safe method for temporary cardiac pacing.

    Atrioventricular sequential pacing using transesophageal atrial pacing in combination with a temporary DDD pacemaker for atrial tracking and ventricular pacing. Roth JV, Huertas R Albert Einstein Medical Center, Philadelphia. J Cardiothorac Vasc Anesth 1995 Jun;9(3):255-8. OBJECTIVE: To determine whether atrioventricular (A-V) sequential pacing can be accomplished using transesophageal atrial pacing (TAP) in combination with a temporary DDD pacemaker for tracking the TAP stimuli and pacing the ventricle via temporary epicardial electrodes. DESIGN: Prospective; patients enrolled consecutively. SETTING: Nonuniversity teaching hospital. PARTICIPANTS: Ten adults undergoing cardiac surgery requiring cardiopulmonary bypass. INTERVENTIONS: Two to six hours after the termination of cardiopulmonary bypass, atrial pacing was initiated via TAP. The atrial system of a temporary DDD pacemaker was connected to surface electrocardiogram (ECG) electrodes. If the temporary pacemaker could track the TAP stimuli and emit pacing stimuli resulting in ventricular capture, A-V sequential pacing was considered to have occurred. The patients were immediately restudied in the same manner with the change that the temporary DDD pacemaker sensed the TAP stimuli via temporary atrial bipolar epicardial electrodes rather than surface ECG electrodes. MEASUREMENTS AND MAIN RESULTS: Dual pacemaker A-V sequential pacing was accomplished in 17 out of 20 attempts. The atrial system of the temporary DDD pacemaker was able to sense the TAP stimulus via temporary atrial bipolar epicardial leads in 10 out of 10 patients and directly from surface ECG electrodes (right arm/left arm) in 7 out of 10 patients. CONCLUSIONS: This report demonstrates that it is possible to A-V sequentially pace using TAP in combination with a temporary DDD pacemaker for tracking the TAP stimulus and pacing the ventricle via temporary epicardial leads. This technique may be useful when A-V sequential pacing is needed and functional temporary atrial leads are not available.

    Transoesophageal Dual-Chamber Pacing. Andersen HR, Pless P. Int J Cardiol 1984 Jun;5(6):745-8. Non-invasive Dual-Chamber Pacing was performed with low threshold current using a newly developed trans-oesophageal lead-electrode in one healthy volunteer.

    The feasibility of gastrothoracic ventricular pacing during transesophageal echocardiography. Kitahata H, Tanaka K, Kimura H, Kawahito S, Oshita S. Department of Anesthesiology, Tokushima University School of Medicine, Japan. hiroshi@clin.med.tokushima-u.ac.jp Anesth Analg 89(1):21-5, 1999. We evaluated whether ventricular pacing is possible using pacing electrodes attached to a transesophageal echocardiography (TEE) probe in 20 patients undergoing elective cardiovascular surgery. A bipolar pacing lead was fixed with silicone adhesive anteriorly to the TEE probe with the distal electrode 25 mm from the TEE probe tip. The TEE probe was positioned to obtain a transgastric short-axis view of the left ventricle. The distal or proximal electrode on the TEE probe was the cathode; the chest electrode placed at the V5 lead position was the anode. Gastrothoracic ventricular pacing (GVP) was performed at 100 bpm at 30- or 50-ms pulse duration. Transgastric ventricular pacing (TVP) was also attempted using both TEE probe electrodes alternately as cathode/anode. Maximal generator output was 32 mA. GVP with the distal electrode as cathode was successful in 75% and 80% of patients at 30- and 50-ms pulse durations and 23.3+/-5.8 mA and 22.6+/-5.8 mA threshold currents, respectively. However, success rates (20% and 25%, respectively) were significantly lower with the proximal electrode as cathode using the same pulse durations and 14.4+/-5.3 mA and 16.7+/-6.8 mA threshold currents. The TVP success rate was significantly lower than that for GVP. With optimization, this system could become an available technique for intraoperative emergency ventricular pacing. IMPLICATIONS: Using an endocardial pacing lead attached to a transesophageal echocardiography probe, gastrothoracic ventricular pacing can be performed successfully without complications in 75%-80% of patients undergoing cardiovascular surgery.

    Transesophageal ventricular stimulation and ventricular tachycardia in the period before implantation of a cardioverter-defibrillator. Pella J, Bodnar J, Stancak B, Misikoa S, Sedlak J, Cizmarik P. Pasteura Univerzity P. J. Safarika, Kosice. Vnitr Lek 1994 Oct;40(10):663-6. The administration of an implantable cardioverter-defibrillator (ICD) is the method of choice in life-threatening ventricular tachyarrhythmias. This effective non-pharmacological intervention was a great advance in the prevention of sudden cardiac death. As to ventricular tachycardias, relapsing ventricular tachycardias based on ischaemic alone need not influence ventricular tachycardia. The mechanism of ventricular tachycardia in ischaemic heart disease is reentry and therefore this arrhythmia can be terminated not only by a defibrillation discharge but also by antitachycardiac stimulation. Various types of antitachycardiac stimulation are part of modern types of ICD. Evidence of the effectiveness of antitachycardiac stimulation (electrophysiological examination) permits to use it also by the transoesophageal approach. This treatment can be very effective and we can thus overcome the period before the definite administration of an ICD, as indicated by the case described.

    Complete atrioventricular block during anesthesia. Mamiya K, Aono J, Manabe M Department of Anesthesiology, Kochi Medical School, Japan. mamiyak@med.kochi-ms.ac.jp. Can J Anaesth 1999 Mar;46(3):265-7. PURPOSE: To describe a case of asymptomatic first degree atrioventricular block with a bifascicular block that progressed to complete atrioventricular block during anesthesia. This potentially fatal block was successfully treated with transesophageal ventricular pacing. CLINICAL FEATURES: A 67-yr-old man was scheduled for microvascular decompression of the right trigeminal nerve under general anesthesia. His preoperative ECG showed first degree atrioventricular block with complete right bundle branch block and left anterior hemiblock, but he had experienced no cardiovascular symptoms. Anesthesia was induced with sevoflurane 5%, and maintained with isoflurane 1.5-2% in oxygen. Fifteen minutes later in the left lateral decubitus position, the systolic arterial blood pressure suddenly decreased from 80 mmHg to 0 mmHg. Then, the ECG abruptly changed from sinus rhythm to complete atrioventricular block. The heart was unresponsive to drug therapy such as atropine 1.3 mg and isoproterenol 0.5 mg, or transcutaneous pacing but transesophageal pacing was successful. CONCLUSION: Asymptomatic first degree atrioventricular block with bifascicular block advanced to complete atrioventricular block during anesthesia. The block was successfully managed with transesophageal pacing.

    The cerebral hemodynamics of patients with ischemic heart disease during transesophageal electrical stimulation of the left atrium. Dudko VA, Vorozhtsova IN, Sokolov AA, Volkova TG, Usov VIu, Shipulin VM. Kardiologiia 1993;33(6):14-6. In 26 patients with coronary heart disease, transesophageal atrial pacing was used to study cerebral hemodynamics from brain tomoscintigraphic findings as compared to the severity of induced of myocardial ischemia, echocardiographic parameters of left ventricular function and prostacyclin-thromboxane balance. In angina pectoris, the lower rate of cerebral blood flow was found  to be correlated with the integral parameter of myocardial ischemia, deteriorated cardiac contractile and pump function, and higher plasma thromboxane A2 levels.

    Transesophageal programmed atrial pacing as a method of selecting patients with sick sinus syndrome for permanent atrial pacing. Swiatecka G, Lubinski A, Raczak G, Stanke A, Juzwa A, Kubica J. Medical Academy of Gdansk, Poland. Pacing Clin Electrophysiol 1988 Nov;11(11 Pt 2):1655-61. Many recent studies have shown transesophageal programmed atrial pacing (TP) as a very practical, safe and convenient way for assessment of sinus node function and AV conduction. On the other hand, permanent atrial pacing is known to be superior to ventricular pacing due to arrhythmogenic and hemodynamic reasons. This is the reason why we decided to use TP as a method of choosing patients with sick sinus syndrome (SSS) for permanent atrial pacing. Sixty-three patients with symptomatic (58) and asymptomatic (5) SSS in a variety of clinical situations were examined in this way. The following electrophysiological features were examined: sinus cycle length, sinus node recovery time as well as corrected time, secondary pause after overdrive stimulation, sinoatrial conduction time, Wenckebach point, induction of supraventricular arrhythmias by S1, S2, S3 programmed stimulation and burst pacing. Patients with abnormal parameters were examined once more after intravenous atropine 0.2 mg/kg to evaluate parasympathetic component. Standard 12-lead ECG was performed in all, and Holter monitoring in most of patients. Twenty-six patients were candidates for permanent AAI pacing. Failures occurred in eight patients usually due to low P wave amplitude and electrode instability. Eighteen patients received AAI pacing systems: eight with brady-tachycardia syndrome, nine with bradyarrhythmia and one with sinoatrial block. In the follow-up of 5-28 months in one patient occurred high degree AV block (II degree) during digitalis therapy. Reduction of doses made this block disappear. Examination of Wenckebach point and possibility of inducation of supraventricular tachyarrhythmias in cases of atrial overexcitability are particularly useful in selecting patients for AAI pacing.

    Transesophageal atrial pacing complications in patients suspected of tachy-brady syndrome. Raczak G, Swiatecka G, Lubinski A, Kubica J. Cardiological Department of IIIrd Internal Clinic, Medical Acadamy of Gdansk, Poland. Pacing Clin Electrophysiol 13(12 Pt 2):2048-53, 1990. The clinical effects of transesophageal atrial pacing (TAP) were assessed in 308 patients. Indications for TAP included evaluation for pacemaker implantation in patients suspected of sinus node dysfunction and determination of the suitable type of pacemaker. Most patients underwent program stimulation including rapid as well as burst stimulation. In one patient, following the study, cerebral arterial embolism occurred, most likely secondary to an induced arrhythmia. That was the only single case of permanent consequences following TAP. Additionally, one patient was accidentally stimulated in the ventricle using low voltage electric current that induced ventricular fibrillation. This was promptly reversed with defibrillation. Twenty-six patients in whom an arrhythmia was previously induced, required medical therapy, two of whom required cardioversion, and 24 required drug therapy, subsequent to clinical intolerance of the arrhythmia. No lethal complications occurred. 

    Transcutaneous cardiac pacing during thoracic surgery. Feasibility and hemodynamic evaluation by transesophageal echocardiography. Amar D, Gross JN, Burt M, Schwinger ME, Rusch VW, Reinsel RA. Department of Anesthesiology and Critical Care Medicine, Memorial Sloan-Kettering Cancer Center, Cornell University Medical College, New York, New York 10021. Anesthesiology 79(4):715-23, 1993. BACKGROUND: Occasionally, emergency perioperative pacing is necessary. Transcutaneous cardiac pacing is noninvasive, safe, and readily available. Its feasibility and hemodynamic effects during thoracic surgery and one-lung ventilation have not been established. METHODS: Twenty anesthetized patients (aged 25-70 yr) without cardiac disease undergoing elective pulmonary resection (right n = 10, left n = 10) were studied in normal sinus rhythm and during transcutaneous cardiac pacing. Patients were paced in supine and lateral decubitus positions (with closed and opened chest) at the minimal current necessary to produce ventricular capture. Invasive arterial monitoring permitted calculation of mean arterial pressure, and transesophageal echocardiography was used to assess atrial and ventricular wall motion and the evaluation of transmitral flow. Twelve patients underwent Doppler analysis of pulmonary venous flow. RESULTS: Pacing was achieved in all patients, with a mean threshold of 86.9 +/- 20.6 mA for the right thoracotomy group, and 106.7 +/- 16.2 mA for the left thoracotomy group. The mean paced heart rates for the right and left thoracotomy groups were 101.6 +/- 18.2 and 105.4 +/- 11.5 beats/min, respectively. During pacing, all patients sustained reversible transient decrements in mean arterial pressure (9-19%) from baseline, the loss of AV synchrony, and the development of paradoxical ventricular septal wall motion. No patient had significant mitral regurgitation during sinus or paced rhythms. Decreased systolic pulmonary venous flow velocity and abnormal systolic flow reversal were seen during pacing in 11 of the 12 patients studied. CONCLUSIONS: Transcutaneous cardiac pacing is effective in patients undergoing thoracotomy and one-lung ventilation. Its use in patients in normal sinus rhythm induces reversible decrements in mean arterial pressure because of the effects of altered atrioventricular association, ventricular wall motion, and pulmonary venous return.

    Transcutaneous pacemaker in cardiovascular emergencies. Azevedo JG, Torres S, Pereira MA, Albuquerque A, Gomes L, Pimenta A. Servico de Cardiologia, Hospital Geral de Santo Antonio. Rev Port Cardiol 1991 Sep;10(9):665-8. OBJECTIVES AND DESIGN OF THE STUDY: Retrospective study to evaluate the efficacy and tolerance of the transcutaneous cardiac pacemaker in the urgent treatment of asystole or severe bradycardia. SETTING: Coronary Care Unit (CCU) and emergency area of the central reference Hospital. PATIENTS: 24 patients, 20 males and four females, aged between 57 and 84 years (mean 70.4 +/- 7.9). Five pts were in asystole and 19 in severe bradycardia. INTERVENTIONS: The transcutaneous pacemaker used, was the "Cardio Aid Zoll NTP" model. The intensity of the electrical stimulation was increased progressively, until electrical capture or intolerable discomfort by the patients was achieved. We defined by electric efficacy, the visualization of pacing spike followed by a deflection due to ventricular depolarization; and by hemodynamic efficacy, the evidence of myocardial contraction, defined as a palpable pulse, synchronous with the pacing artefact. MAIN RESULTS: Stimulation threshold ranged from 30 to 140 mA (mean 67.7 +/- 23.4). The duration of pacing was from 15 minutes to 13 hours, being more than one hour in only four situations. From the 20 conscious patients, or the ones who got conscious, 15 (75%) tolerated well the stimulation. It was intolerable in five pts (25%). No significative side effects due to the use of transcutaneous pacemaker were observed. CONCLUSIONS: The transcutaneous pacemaker was efficient in the electric and hemodynamic stabilization in the majority of patients. It was generally well tolerated and without important side effects. We think that it may be a valid alternative to transvenous pacing technics in the treatment of asystole and severe bradycardia situations.

    Transcutaneous pacing: experience with the Zoll noninvasive temporary pacemaker. Madsen JK, Meibom J, Videbak R, Pedersen F, Grande P. Medical Department B, Rigshospitalet, University Hospital, Copenhagen, Denmark. Am Heart J 1988 Jul;116(1 Pt 1):7-10. We investigated the effectiveness of noninvasive transcutaneous pacing in 35 patients. Pacing was achieved in 33 of 35 patients (94%). In 24 patients the indications were: acute sinoatrial block, atrioventricular block, or asystole with unconsciousness due to acute myocardial infarction in eight; sick sinus node syndrome in 12; and other indications in four patients. These patients were paced for 2 minutes to 14 hours; the median length of pacing was 15 minutes. The pacing thresholds varied from 30 to 110 mA; pacing was achieved in 22 patients without serious side effects. Nine patients needed sedation and six were unconscious; 12 later had a temporary or permanent transvenous pacemaker implanted. In 11 patients noninvasive transcutaneous pacing was performed prior to implantation of a permanent pacing catheter: in eight pacing was done just prior to catheter insertion, and in three the threshold was determined before a weekend on which the patient had to wait for implantation. Pacing thresholds were from 45 to 90 mA; the median was 55 mA. Seven of these eight patients felt chest pain. No serious side effects were seen. We conclude that transcutaneous pacing is effective and safe and can be used instead of inserting a transvenous catheter if this is impossible or until one can be inserted.

    External noninvasive temporary cardiac pacing: clinical trials. Zoll PM, Zoll RH, Falk RH, Clinton JE, Eitel DR, Antman EM. Circulation 1985 May;71(5):937-44. An external cardiac pacemaker-monitor has been developed that provides safe, effective noninvasive ventricular stimulation that is well tolerated in conscious patients and allows clear recognition of electrocardiographic response. The noninvasive temporary pacemaker (NTP) has now been applied in 134 patients in five hospitals. Stimulation was tolerated well in 73 of 82 conscious patients, and nine found it intolerable. The NTP was effective in evoking electrocardiographic responses in 105 patients; the 29 failures were in the presence of prolonged hypoxia or severe discomfort. The NTP was clinically useful in 82 patients: 43 of 86 were resuscitated from emergency or expected arrest, 38 of 40 were maintained in standby readiness for up to 1 month but did not require stimulation, and one of eight patients with tachycardia obtained some clinical benefit. The NTP was especially useful in 25 patients with complications or contraindications to endocardial pacing and in 57 patients in whom insertion of an endocardial electrode was avoided.