Ann Thorac Surg 1998;65:632-636
© 1998 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Temporary Atrial Electrode for the Treatment of Supraventricular Tachycardia After Cardiac Operations
Hormoz Mehmanesh, MD,
Rüdiger Lange, MD,
Siegfried Hagl, MD
Department of Cardiac Surgery, University of Heidelberg, Heidelberg, Germany
Accepted for publication August 23, 1997.
Dr Mehmanesh, Department of Cardiac Surgery, University of Heidelberg, Chirurgische Klinik, INF 110, 69120 Heidelberg, Germany.
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Abstract
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Background. Supraventricular tachycardia is a common postoperative complication early after cardiac operations. A temporary atrial patch electrode for low-energy atrial defibrillation was developed in 1992 and subsequently tested.
Methods. The electrode first was tested and removed intraoperatively during open heart operations in 10 patients (phase I). After the intraoperative testing, the temporary atrial patch electrode was implanted in 20 patients for postoperative termination of spontaneous episodes of supraventricular tachycardia (phase II). When supraventricular tachycardia occurred, biphasic shocks (1.2 to 5 J) were applied and the atrial defibrillation thresholds were measured.
Results. In phase I, the mean intraoperative atrial defibrillation threshold was 1.6 ± 1.4 J, with a mean shock impedance of 64 ± 7.3 
. In phase II, 6 of 20 patients (30%) had 7 episodes of atrial fibrillation (n = 6) and atrial flutter (n = 1) after operation. In 5 patients, the supraventricular tachycardia could be converted to a sinus (n = 5) or normofrequent atrioventricular rhythm (n = 1). The mean postoperative defibrillation threshold was 2.7 ± 2.1 J, with a mean shock impedance of 50.2 ± 6.8 .
Conclusions. The temporary atrial patch electrode allows low-energy defibrillation of episodes of atrial fibrillation. It may serve as an alternative therapeutic option for the treatment of supraventricular tachycardia.
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Introduction
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Supraventricular tachycardia (SVT), such as atrial fibrillation (AF), atrial flutter, and atrioventricular reentrant tachycardia, is a common complication after heart operations. The incidence of postoperative SVT has been reported to be as high as 69% (range, 13% to 69%) early after operation [1][2][3][4][5][6][7][8][9][10][11]. During SVT, the loss of adequate atrial filling leads to a decrease in cardiac output, which may compromise patients with impaired left ventricular function [12][13]. The standard therapy for SVT consists of the use of cardiac glycosides [14][15] and calcium antagonists [16] to control the heart rate. In patients with atrial flutter, overpacing is used to reestablish a sinus rhythm [17].
In some patients, drugs are not effective in terminating postoperative SVT or are contraindicated because of major negative inotropic side effects. In these patients, external atrial defibrillation, synchronized to the R wave of the electrocardiogram, is the only means of terminating the arrhythmia [18]. However, because of the high energy required (40 to 360 J), the application of shocks is not tolerated by a conscious patient. Therefore, external defibrillation usually is performed under anesthesia.
There is some evidence that SVT also can be terminated with low-energy shocks. For instance, during operation, AF is terminated with paddles placed directly on the heart. This kind of defibrillation requires considerably less energy than the transthoracic procedure, because all the defibrillation current is applied to the tissue that needs to be defibrillated. The energy level reported to be effective in terminating AF, using the intrathoracic paddle electrodes, is 1 J for monophasic pulses and 0.3 J for biphasic pulses. Low-energy defibrillation of AF also is possible with a transvenous system (coronary sinus versus right atrial electrodes). The mean defibrillation threshold is reported to be about 2 J [19].
On the basis of these experiences, we designed a temporary electrode in 1992 that subsequently was developed by the Bakken Research Center (Medtronic Inc, Maastricht, the Netherlands). The Temporary Atrial Patch Electrode (TAPE) can be attached to the exposed atria during cardiac operations and removed after the early postoperative period. The purpose of this study was to investigate whether atrial defibrillation using the temporary electrode could be performed safely, effectively, and with considerably less energy than is required for transthoracic defibrillation.
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Material and Methods
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The TAPE consists of a polytetrafluoroethylene felt pad measuring about 3 x 5 cm in which three parallel stainless steel defibrillation wire electrodes are mounted. The pad contains holes that expose the electrode wires in a discontinuous fashion. The three electrode wires are merged into one polyurethane-insulated lead body, proximal to the pad. At the proximal end of the lead body, a stainless steel connector pin with a breakaway needle is mounted for percutaneous exteriorization of the lead pin. The breakaway needle can be broken off to make the connector pin suitable for patient cable connection. The polytetrafluoroethylene pad remains attached to the atria after removal of the metallic temporary electrode sections (Fig 1).
The clinical investigation was carried out in two parts: intraoperative (phase I) and postoperative (phase II) application of the TAPE. The study was approved by the Ethical Committee on Human Research of the University of Heidelberg and informed consent was given by every patient. Patients with a preoperative sinus rhythm and a left atrial diameter of less than 50 mm were included in the study. Patients with implanted devices (eg, pacemakers, defibrillators, the Cardiomyostimulator) and previous cardiac operations were excluded.
Phase I
The TAPE was implanted for intraoperative testing in 18 patients undergoing coronary artery bypass grafting. Four patients were excluded because of absence of a sinus rhythm and another 4 because of hemodynamic instability after the cardiopulmonary bypass period. The testing was completed in 10 patients (Table 1). In each patient, one TAPE was fixed to the left atrium between the pulmonary veins using 4/0 polypropylene (Prolene; Ethicon, Somerville, NJ) sutures during cardioplegic cardiac arrest. Another TAPE was implanted on the lateral free wall of the right atrium after the patient had been weaned from cardiopulmonary bypass (Fig 2). Bipolar heart wires were placed on the right atrium and ventricle. When a sinus rhythm was present, AF was induced with a 50-Hz alternating current fibrillator through the bipolar atrial heart wires. For defibrillation, biphasic truncated capacitor discharge pulses (capacitance: 120 microfarad; tilt: 65% per phase) were generated by an external cardioverter-defibrillator (model 5358; Medtronic Inc). An intraoperative defibrillation threshold protocol was designed to obtain information regarding the defibrillation threshold and the dependence of the defibrillation success rate on the stored energy level. The protocol was set up to obtain defibrillation success rate values at three energy levels (range, 0.6 to 5.0 J). At each energy level, three consecutive defibrillation attempts were carried out. The total number of shocks delivered was nine.
Phase II
After the intraoperative testing, the TAPE was implanted in 20 patients for postoperative termination of spontaneous episodes of SVT (Table 2). When SVT occurred, biphasic shocks with the same characteristics used for the intraoperative testing were applied for cardioversion without prior sedation or analgesia. Patients did not receive any antiarrhythmic medication until the first episode of tachycardia occurred. To obtain the defibrillation thresholds for postoperative termination of SVT, every cardioversion attempt was begun at a shock strength of 1.2 J and increased to a maximum of 5 J on failure to terminate the tachycardia. Acetyldigoxin and verapamil were administered either on failure of cardioversion at 5 J or on recurrence of tachycardia after successful cardioversion to a sinus rhythm (Fig 3). After every cardioversion, patients were asked to indicate their subjective pain perception on a four-point scale that ranged from not painful to mildly painful to painful to very painful.
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Results
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Phase I: Intraoperative Results
The intraoperative testing was completed in 10 patients. Induction of AF was difficult to achieve with alternating current in some patients, either because of inability to produce AF or because of the spontaneous termination of such episodes before shock delivery. The number of induction attempts made was 17.2 ± 8.2 to achieve 7.1 ± 2.3 effective periods of AF (n = 10). In 4 of 10 patients, the ratio of induction attempts to effective inductions was greater than three. No ventricular arrhythmias occurred as a consequence of the inductions. The duration of the shock protocol was 12.3 ± 3.9 minutes.
All shocks were synchronized to the R wave, which was sensed through bipolar temporary heart wires. The R wave amplitude of the signal for synchronization of the atrial defibrillation shocks was 7.2 ± 2.6 mV (n = 10). With programmed sensitivity settings of 0.3 mV (n = 9) and 0.5 mV (n = 1), no sensing failures were present at any of the defibrillation shocks.
The defibrillation results are summarized in Table 3. The mean intraoperative atrial defibrillation threshold was 1.6 ± 1.4 J. The mean shock impedance was 64 ± 7.3 (minimum, 52 ; maximum, 78 ). Probit analysis of the individual success/failure data resulted in individual dose-response curves, which were summed to give the composite curve (Fig 4).
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Defibrillation success rate (DSR) curves calculated from the individual DSR curves. (SD = standard deviation.)
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No ventricular arrhythmias occurred as a consequence of AF induction or termination. No complications related to the implantation or removal of the electrodes were observed.
Phase II: Postoperative Results
Six (30%) of 20 patients had 7 spontaneous episodes of SVT after operation (AF: 6; atrial flutter: 1). In 5 patients, the SVT was converted to a sinus rhythm (n = 5) or a normofrequent atrioventricular rhythm (n = 1). The mean defibrillation threshold was 2.7 ± 2.1 J. The mean shock impedance was 50.2 ± 6.8 (Table 4). In 1 patient, the cardioversion was not successful, even with a 5-J shock. Radiologic examination of this patient revealed a dislocation of the left atrial TAPE.
Acetyldigoxin and verapamil were necessary in 2 patients for maintenance of a sinus rhythm. The patients subjectively rated the shocks they received as either "mildly painful" (n = 10) or "painful" (n = 4). No postshock ventricular arrhythmia was observed and the TAPE was removed easily after a mean of 10.6 ± 5.3 days by traction without injury to the atria. In 1 patient, the TAPE was removed after 7 days during a repeated thoracotomy performed because of sternal instability.
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Comment
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Paroxysmal SVT is a major complication early after cardiac operations. Especially in patients with compromised left ventricular function, the lack of atrioventricular synchronicity ("atrial kick") has deleterious effects on hemodynamic stability. A variety of risk factors have been suggested for this type of postoperative tachycardia, including age [20], right coronary artery stenosis [21], type of cardioplegia [1][2] and preoperative medication [3]. Sex, cross-clamp time, creatine kinase peak, hemoglobin and hematocrit levels, and number of bypass grafts also have been evaluated as independent risk factors for postoperative SVT [3][4]. The wide range in the reported incidence of SVT after cardiac operations (13% to 63%) probably is related to variations in the patient populations studied and the perioperative management strategies used.
The treatment of SVT is designed primarily to reduce the ventricular response rate [22]. Various antiarrhythmic drugs have been suggested for treatment, such as digitalis, calcium antagonists, sotalol, adenosine, and disopyramide [15][16][23][24][25]. However, none of these agents primarily restores atrioventricular synchrony. Further, the hemodynamic condition of the patient may be compromised because of the negative inotropic side effects of these drugs. In patients with persistent AF (48 to 72 hours), thromboembolic complications such as stroke may occur and systemic anticoagulation is required [2]. In some patients with atrial flutter, atrial overpacing is successful [17]. Transthoracic electrical cardioversion is suggested for the termination of persistent SVT [18]. The incidence of SVT is low in the first 24 hours after operation and high in the next 48 hours, when patients already are extubated [4]. Therefore, general anesthesia often is required for external cardioversion, and this procedure cannot be repeated incessantly in the event of recurrent SVT.
The concept of a low-energy cardioversion of SVT, using a temporary lead, therefore seems reasonable. The results of this study demonstrate the feasibility of clinical application of the TAPE in a small group of patients. Taking into account that a worst-case protocol is used (ie, multiple shocks for defibrillation threshold measurement with no sedation or analgesia), the pain levels of the patients are acceptable using low-energy shocks of approximately 2 J. Although the TAPE is very effective in the cardioversion of SVT to a sinus rhythm, it should be noted that the problem of maintaining a stable rhythm still remains. In patients with multiple recurrences of SVT, cardioversion can be repeated safely, but antiarrhythmic drugs are needed to maintain a sinus rhythm. Further studies are required to determine whether a lower drug dosage can be used in these circumstances.
Another problem is the polytetrafluoroethylene patch section that remains in the patient after removal of the metallic electrode portion of the TAPE. Although follow-up examination of our patients did not reveal any adverse effects associated with the remaining patch section, it has been eliminated in the new prototypes of the electrode. A European multicenter clinical trial is planned to investigate these new prototypes.
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References
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- Fontan F, Madonna F, Naftel DC, Kirklin JW, Blackstone EH, Digerness S Modifying myocardial management in cardiac surgery: a randomized trial. Eur J Cardiothorac Surg 1992;6:127-136.[Abstract/Free Full Text]
- Flack JE, III, Hafer J, Engelman RM, Rousou JA, Deaton DW, Pekow P Effects of normothermic blood cardioplegia on postoperative conduction abnormalities and supraventricular arrhythmias. Circulation 1992;86(Suppl 2):385-392.
- Suttorp MJ, Kingma JH, Peels HO, et al. Effectiveness of sotalol in preventing supraventricular tachyarrhythmias shortly after coronary artery bypass grafting. Am J Cardiol 1991;68:1163-1169.[Medline]
- Crosby LH, Woll KR, Wood KL, Pifalo WB Effect of activity on supraventricular tachyarrhythmias after coronary artery bypass surgery. Heart Lung 1990;19:666-670.[Medline]
- Martinussen HJ, Lolk A, Szczepanski C, Alstrup P Supraventricular tachyarrhythmias after coronary bypass surgery: a double blind randomized trial of prophylactic low dose propranolol. Thorac Cardiovasc Surg 1988;36:206-207.[Medline]
- Kleinpreter UM, Iversen S, Tesch A, Schmiedt W, Mayer E, Oelert H Prevention of supraventricular tachyarrhythmias post coronary artery bypass surgery. Eur Heart J 1987;8(Suppl L):137-140.
- Janssen J, Loomans L, Harink J, et al. Prevention and treatment of supraventricular tachycardia shortly after coronary artery bypass grafting: a randomized open trial. Angiology 1986;37:601-609.[Medline]
- Davison R, Hartz R, Kaplan K, Parker M, Feiereisel P, Michaelis L Prophylaxis of supraventricular tachyarrhythmia after coronary bypass surgery with oral verapamil: a randomized, double-blind trial. Ann Thorac Surg 1985;39:336-339.[Abstract/Free Full Text]
- Ivey MF, Ivey TD, Bailey WW, Williams DB, Hessel EA, II, Miller DW, Jr Influence of propranolol on supraventricular tachycardia early after coronary artery revascularization. A randomized trial. J Thorac Cardiovasc Surg 1983;85:214-218.[Abstract]
- Sgarbieri RN, de-Freitas JN, Evora PR, et al. Postoperative atrial fibrillation in myocardial revascularization. Arq Bras Cardiol 1989;52:19-22.[Medline]
- Gavaghan TP, Feneley MP, Campbell TJ, Morgan JJ Atrial tachyarrhythmias after cardiac surgery: results of disopyramide therapy. Aust N Z J Med 1985;15:27-32.[Medline]
- Ausubel K, Steingart RM, Shimshi M, Klementowicz P, Furman S Maintenance of exercise stroke volume during ventricular versus atrial synchronous pacing: role of contractility. Circulation 1985;72:1037-1043.[Abstract/Free Full Text]
- Baller D, Hoeft A, Korb H, Wolpers HG, Zipfel J, Hellige G Basic physiological studies on cardiac pacing with special reference to the optimal mode and rate after cardiac surgery. Thorac Cardiovasc Surg 1981;29:168-173.[Medline]
- Alvarez JR Prophylactic digoxin and SVT in cardiac surgery. Am Heart J 1983;106:606.
- Parker FB, Jr, Greiner-Hayes C, Bove EL, Marvasti MA, Johnson LW, Eich RH Supraventricular arrhythmias following coronary artery bypass. The effect of preoperative digitalis. J Thorac Cardiovasc Surg 1983;86:594-600.[Abstract]
- Waxman HL, Myerburg RJ, Appel R, Sung RJ Verapamil for control of ventricular rate in paroxysmal supraventricular tachycardia and atrial fibrillation or flutter: a double-blind randomized cross-over study. Ann Intern Med 1981;94:1-6.[Abstract/Free Full Text]
- Sen S, Rettig G, Frohlig G, Doenecke P, Schieffer H, Bette L Sustained atrial flutter after cardiac surgery: successful termination by rapid atrial pacing. Thorac Cardiovasc Surg 1984;32:41-44.[Medline]
- Lown B Electrical reversion of cardiac arrhythmias. Br Heart J 1967;29:469-489.[Free Full Text]
- Murgatroyd FD, Slade AK, Sopher SM, Rowland E, Ward DE, Camm AJ Efficacy and tolerability of transvenous low energy cardioversion of paroxysmal atrial fibrillation in humans. J Am Coll Cardiol 1995;25:1347-1353.[Abstract]
- Leitch JW, Thomson D, Baird DK, Harris PJ The importance of age as a predictor of atrial fibrillation and flutter after coronary artery bypass grafting. J Thorac Cardiovasc Surg 1990;100:338-342.[Abstract]
- Mendes LA, Connelly GP, McKenney PA, et al. Right coronary artery stenosis: an independent predictor of atrial fibrillation after coronary artery bypass surgery. J Am Coll Cardiol 1995;25:198-202.[Abstract]
- Pires LA, Wagshal AB, Lancey R, Huang SK Arrhythmias and conduction disturbances after coronary artery bypass graft surgery: epidemiology, management, and prognosis. Am Heart J 1995;129:799-808.[Medline]
- Rizos I, Seidl KH, Aidonidis I, Stamou S, Senges J, Toutouzas P Intraindividual comparison of diltiazem and verapamil on induction of paroxysmal supraventricular tachycardia. Cardiology 1994;85:388-396.[Medline]
- Sung RJ, Tan HL, Karagounis L, et al. Intravenous sotalol for the termination of supraventricular tachycardia and atrial fibrillation and flutter: a multicenter, randomized, double-blind, placebo-controlled study. Am Heart J 1995;129:739-748.[Medline]
- Sethi KK, Singh B, Kalra GS, Arora R, Khlilullah M Comparative clinical and electrophysiologic effects of adenosine and verapamil on termination of paroxysmal supraventricular tachycardia. Indian Heart J 1994;46:141-144.[Medline]
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Abstract
Introduction
