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Ann Thorac Surg 1997;63:1589-1591
© 1997 The Society of Thoracic Surgeons

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Original Article: Cardiovascular

Surgical Management of Ventricular Tachycardia

Division of Cardiovascular and Thoracic Surgery, University of Minnesota, Minneapolis, Minnesota

Accepted for publication February 20, 1997.

	Abstract

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Background. Ventricular tachyarrhythmias are the leading cause of death from coronary artery disease. A small percentage of these arrhythmias originate in chronically ischemic myocardium, rather than acutely ischemic myocardium, and can be refractory to medical management. Epicardial mapping and focal cryoablation of foci demonstrating early activation may provide definitive therapy when pharmacologic management fails. We report a series of 42 consecutive patients with refractory ventricular tachycardia (VT) who were treated with open epicardial mapping and focal cryoablation after pharmacologic management failed.

Methods. We retrospectively reviewed the records of patients who underwent surgical treatment of malignant VT. For patients not recently seen in the clinic, we conducted telephone interviews. At the time of operation, epicardial mapping was performed to locate foci of early electrical activation. These foci were then cryoablated, using 2-minute applications of liquid nitrogen-cooled probes. All patients underwent postoperative electrophysiologic studies to test for inducible VT.

Results. Of these 42 patients, 34 (81%) were male, 8 (19%) female. Average age was 62.9 ± 10.6 years; ejection fraction, 0.20 (range, 0.04 to 0.50); and number of foci ablated, 2.1 ± 1.1 (range, 1 to 6). At the time of cryoablation, all patients underwent additional procedures, including aneurysmectomy, coronary artery bypass, or valve replacement. The 30-day operative mortality was 9.5% (4 of 42). Of the 38 survivors, 36 (94.7%) were clinically free of VT; the remaining 2 had spontaneous or inducible VT.

Conclusions. Open cryoablation of foci propagating VT appears to be safe and effective. It may be the most definitive treatment for malignant VT.

	Introduction

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Of the 700,000 deaths each year caused by heart disease in the United States, 60% to 65% are sudden and are presumed to be caused by tachyarrhythmias [1]. In fact, ventricular tachyarrhythmias are the leading cause of death due to coronary artery disease [2–4]. Most episodes of ventricular tachycardia (VT) arise from acutely ischemic myocardium and are best treated by electrocardioversion, cellular membrane stabilization, potentiation of oxygen delivery, and restoration of blood flow. A small percentage of VT episodes originate in chronically ischemic or infarcted myocardium and present more controversial treatment options [5].

Pharmacologic therapy is the primary means to prevent recurrence of VT. However, 50% to 60% of such patients have arrhythmias that are refractory to medical management; they experience recurrent episodes of VT while taking antiarrhythmics [6]. They require more aggressive treatment. In the past this has included thoracic sympathectomy, coronary artery bypass grafting, endocardial resection, and endocardial ventriculotomy [7–9].

More recently, cryoablation (via percutaneous catheter) of foci responsible for the initiation and propagation of VT has been used. Failure rates of catheter ablative techniques have ranged from 41% to 82%, with failure defined as spontaneous or inducible VT refractory to medications [10–12]. In addition, catheter ablation has significant associated morbidity and mortality. The largest combined study of 164 patients undergoing catheter ablation procedures for VT had a 6.7% mortality rate related to the procedure, and another 21% of patients died within the first year [10].

Given these results, we thought that further investigation was warranted into open cardiac mapping and direct cryoablation of foci responsible for the initiation and propagation of VT. We therefore reviewed our series of 42 patients treated with open mapping and focal cryoablation.

	Patients and Methods

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
We reviewed the records of 42 consecutive patients with refractory VT who were treated with open cryoablation of foci demonstrating early electrical activation and propagation of VT. All had prior myocardial infarction and recurrent VT caused by ischemic heart disease. All had recurrent episodes of VT while taking antiarrhythmics; their disease was considered refractory to pharmacologic management. All other therapeutic options had been exhausted before deciding on operative intervention. All patients were high risk because of severe concomitant heart disease.

Our retrospective chart review included hospital records, clinic notes, and correspondence from patients and primary physicians. For patients who had not had a recent clinic visit, we conducted telephone interviews with them, their family, or their primary physician.

Data collected included patient age and sex, preoperative left ventricular ejection fraction (determined by multigated blood pool acquisition, echocardiography, or ventriculography), preoperative and postoperative medications, electrophysiologic study results, number of foci ablated, additional operative procedures performed, time to return of ventricular tachycardia, and patient survival.

For the operative mapping and focal cryoablation, we used the following method: after initiation of cardiopulmonary bypass and before hypothermic cardioplegic arrest, intraoperative mapping of foci exhibiting early electrical activation was obtained by placing an electrosensitive grid directly on the epicardium, followed by attempts to induce VT by electrical stimulation. Suspicious areas were then located through grid coordinates. Hypothermic cardioplegic arrest was initiated, the left ventricle was opened, and these areas were ablated using a probe cooled by liquid nitrogen (-51°C) placed at each site for 2 minutes. If suspicious areas could not be ablated satisfactorily, an implantable cardioverter defibrillator (ICD) was placed. Areas bordering left ventricular aneurysmal scar tissue were also cryoablated. Endomyocardial resection was not performed. Additional surgical procedures, including left ventricular aneurysmectomy, valve replacement, and coronary artery bypass, were done using standard techniques while the patient was undergoing cardiopulmonary bypass and cold cardioplegic arrest. To determine the efficacy of the procedure, all surviving patients routinely had electrophysiologic studies 1 to 2 weeks after the operation.

Actuarial survival was determined by Cox analysis and included perioperative deaths.

	Results

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
A total of 42 patients, 34 (81%) male and 8 (19%) female, underwent open epicardial mapping and focal cryoablation. Average age at the time of operation was 62.9 ± 10.6 years (range, 32 to 78 years); average preoperative left ventricular ejection fraction, 0.20 (range, 0.04 to 0.50); and average number of foci ablated per patient, 2.1 ± 1.1 (range, 1 to 6 sites). All patients had severe concomitant heart disease. At the time of operation, 16 (38.1%) had congestive heart failure, unstable angina, or a myocardial infarction documented within the previous 4 months.

Mean follow-up was 30.7 months (range, 3 to 69 months). Of the 42 patients, 4 died within 30 days of operation, resulting in a mortality rate of 9.5%. One died of left ventricular failure in the operating suite, 1 died of left ventricular failure after a prolonged intensive care unit stay, 1 died of acute occlusion of a left anterior descending coronary artery bypass graft on postoperative day 6, and 1 died of multisystem organ failure on postoperative day 8. Of the 38 survivors, 36 (94.7%) were clinically free of spontaneous and inducible VT at the time they left the hospital. One had an episode of spontaneous VT and another had inducible VT (while receiving amiodarone) during postoperative electrophysiologic studies; both had ICDs placed before they left the hospital. Long-term data were collected on 34 patients; 4 were lost to follow-up beyond 3 months.

All patients had additional necessary procedures done at the time of cryoablation: 25 (59.2%), left ventricular aneurysmectomy plus coronary artery bypass; 12 (28.6%), left ventricular aneurysmectomy alone; 1 (2.4%), coronary artery bypass alone; 1 (2.4%), aneurysmectomy and mitral valve replacement; 2 (4.8%), aneurysmectomy, coronary artery bypass, and placement of an ICD; and 1 (2.4%), aneurysmectomy plus ICD placement.

Of the 34 patients available for long-term follow-up, 4 (11.8%) have had return of spontaneous VT. Average time to return of spontaneous VT was 37.5 months. During follow-up, 8 (26%) patients had episodes of either sustained or unsustained VT inducible during electrophysiologic studies. All but 1 of these 8 patients had their VT rendered noninducible with amiodarone. No patient died of documented or suspected VT during follow-up. With operative deaths included, the survival rate was 78% at 1 year and 60% at 4 years.

Of the 34 long-term survivors available, 6 died during follow-up at an average of 18.2 months after the operation (range, 1.5 to 51 months): 2 of congestive heart failure and 1 each of myocardial infarction, stroke, pneumonia, and the complications of end-stage renal failure.

	Comment

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Most VT arises from acutely ischemic myocardium, but a small percentage arises from chronically infarcted myocardium. The treatment for VT from acutely ischemic tissue has been well described. But the treatment for recurrent malignant VT from chronically infarcted tissue is less well defined and more controversial. Several treatment options have been advocated over the past 30 years. Initially, refractory ischemic VT was treated by thoracic sympathectomy, coronary artery bypass grafting, or aneurysm resection [7]. These approaches met with limited success. It was not until 1978 that Guiraudon and associates [8] advocated encircling endocardial ventriculotomy. A short time later, Josephson and associates [9] advocated localized endocardial resection as the procedure of choice. In 1983, a group at Duke University became the first to advocate some role for cryoablation [13].

The primary surgical indication for treatment is an ischemic VT that has proved refractory to pharmacologic management. In reality, 50% to 60% of patients with VT require more aggressive therapy [6]. Percutaneous catheter ablation of foci responsible for the initiation of ventricular tachycardia would seem an attractive option, but high failure rates are well documented [10–12, 14]. When patients with multiple foci are considered, failure rates may be even higher. In addition, catheter ablation for VT is not without risk. In the largest combined series of 164 patients with follow-up of 12 months, 21% died of cardiac-related causes [10]. The procedure itself has a mortality rate of 6.7% [10]. This somewhat limited success rate, as well as the inability to perform additional necessary procedures, makes catheter ablation best suited to patients unable or unwilling to undergo an open operative procedure.

The only contraindication for surgical treatment of ischemic VT is severe left ventricular dysfunction [15], defined by New York Heart Association class III or class IV heart failure with or without left ventricular aneurysm. When left ventricular aneurysm does not yet exist, a fresh infarct is present. If an emergency (as opposed to elective) operation is done for intractable VT, patients have a much higher surgical risk.

Our series of patients had exhausted all other forms of therapy for potentially lethal VT. As a group, they underwent multiple surgical procedures at the time of open cryoablation. Their heart disease is primarily ischemic in nature, with a low measured ejection fraction, yet their immediate survival rate was 90.5%. The four episodes of spontaneous VT that occurred, on average, more than 3 years after the operation are likely the result of new foci of infarct or ischemia.

Endocardial resection is not necessary for successful treatment of VT; aggressive guided cryoablation was as effective in our series. The need for additional procedures (such as coronary artery bypass grafting, left ventricular aneurysmectomy, valve repair or replacement, or ICD placement) suggests that operation may offer the most cost-effective and definitive therapy for this patient population. Nonoperative catheter ablation has a role in the treatment of refractory VT, but should be considered only after operative intervention has been ruled out. Further investigation is needed. A prospective, randomized trial may be the best approach to determine the optimal care for patients with refractory VT and for fine-tuning the indications for open (versus catheter-delivered) treatment.

	Footnotes

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Address reprint requests to Dr Shumway, Division of Cardiovascular and Thoracic Surgery, University of Minnesota, Box 207 UMHC, 420 Delaware St SE, Minneapolis, MN 55455 (e-mail: shumw001{at}maroon.tc.umn.edu).

	References

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 

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4. Holmes DR, Davis KB, Mock MR, et al. The effect of medical and surgical treatment on subsequent sudden cardiac death in patients with coronary artery disease: a report from the Coronary Artery Surgery Study. Circulation 1986;73:1254–63.[Abstract/Free Full Text]
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8. Guiraudon G, Fontaine G, Frank R, Escande G, Etievent P, Cabrol C. Encircling endocardial ventriculotomy: a new surgical treatment for life-threatening ventricular tachycardias resistant to medical treatment following myocardial infarction. Ann Thorac Surg 1978;26:438–44.[Abstract]
9. Josephson ME, Horowitz LN, Harken AH. Endocardial excision: a new surgical technique for the treatment of ventricular tachycardia. Circulation 1979;60:1430–9.[Abstract/Free Full Text]
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12. Trappe HJ, Klein H, Auricchio A, Wenzlaff P, Lichtlen PR. Catheter ablation of ventricular tachycardia: role of the underlying etiology and the site of energy delivery. PACE 1992;15:411–24.
13. Holman WL, Ikeshita M, Douglas JM Jr. Ventricular cryosurgery: acute effects on intramural electrophysiology. Ann Thorac Surg 1983;35:386–93.[Abstract]
14. Scheinman MM, Laks MM, Di Marco J, Plumb V. Current role of catheter ablative procedures in patients with cardiac arrhythmias: a report for health professionals from the subcommittee on Electrocardiography and Electrophysiology, American Heart Association. Circulation 1991;83:2146–53.[Abstract/Free Full Text]
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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Sara J. Shumway Jolene M. Kriett Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shumway, S. J. Articles by Ring, W. S. Search for Related Content PubMed PubMed Citation Articles by Shumway, S. J. Articles by Ring, W. S.