Surgical management of post–myocardial infarction ventricular tachyarrhythmia by myocardial debulking, septal isolation, and myocardial revascularization

Surgical therapy of ventricular arrhythmias

Since the advent of implantable cardioverters/defibrillators (ICD) and percutaneous ablation, surgery for the treatment of ventricular arrhythmia has decreased tremendously. Nevertheless, surgical treatment of ventricular arrhythmias is still required, especially for cases where ICD discharge occurs very frequently or in patients with other indications for surgery. The choice of surgical therapy may range from radiofrequency- or cryoablation of a single focus (identified either intra- operatively or percutaneously) to more extensive surgical procedures such as surgical ventricular reconstruction with endocardial resection or even resection of the right ventricle and the creation of a cavo-pulmonary circulation for malignant arrhythmias and right ventricular failure in patients with arrhythmogenic right ventricular dysplasia. However, the choice of surgical procedure should be made based on the pathomechanism of the arrhythmia. This is important because any incision in the left or right ventricle or percutaneous ablation may also be the cause for ventricular arrhythmia. In this short review we will describe the most common underlying substrates for ventricular arrhythmia, indications for surgery, the techniques used for treatment and the results achieved. We will conclude that for most cases of patients with ventricular arrhythmia undergoing surgery, ischemia and the presence of a scar after myocardial infarction is the underlying cause and revascularization plus surgical ventricular reconstruction with endocardial resection may be the best treatment option.

Factors affecting late survival after surgical remodeling of left ventricular aneurysms

OBJECTIVES

Surgical remodeling of the left ventricle has involved various techniques of volume reduction. This study evaluates factors that influence long-term survival results with 3 operative methods.

METHODS

From 1979 to 2000, 157 patients (134 men, mean age 61 years) underwent operations for class III or IV congestive heart failure, angina, ventricular tachyarrhythmia, and sudden death after anteroseptal myocardial infarction. The preoperative ejection fraction was 28% +/- 0.9% (mean +/- standard error), and the pulmonary artery occlusive pressure was 15 +/- 0.07 mm Hg. Cardiogenic shock was present in 26 patients (16%), and an intra-aortic balloon pump was used in 48 patients (30%). The type of procedure depended on the extent of endocardial disease and was aimed at maintaining the ellipsoid shape of the left ventricle cavity. In group I patients (n = 65), radical aneurysm resection and linear closure were performed. In group II patients (n = 70), septal dyskinesis was reinforced with a patch (septoplasty). In group III patients (n = 22), ventriculotomy closure was performed with an intracavitary oval patch.

RESULTS

Hospital mortality was 16% (25/157) and was similar among the groups. Actuarial survival up to 18 years was better with a preoperative ejection fraction of 26% or greater (P =.004) and a pulmonary artery occlusive pressure of 17 mm Hg or less (P =.05). Survival was worse in patients who had intra-aortic balloon pump support (P =.03). Five-year survival for all patients in group III was higher than for patients in group II (67% vs 47%, P =.04).

CONCLUSIONS

Factors that improved long-term survival after left ventricular surgical remodeling were intraventricular patch repair, preoperative ejection fraction of 26% or greater, and pulmonary artery occlusive pressure of 17 mm Hg or less without the need for balloon pump assist.

Identifying patients at low risk of death from cardiac failure after operation for postinfarct ventricular tachycardia

BACKGROUND

In unselected patients, cardiac failure accounted for most deaths after antiarrhythmic operation (ER) for postinfarction ventricular tachycardia (VT). This study aimed to determine whether patients at low risk of this outcome could be predicted from a retrospective analysis of variables from 100 consecutive ER patients.

METHODS

Thirteen variables suggested by other researchers as predictive of outcome were analyzed. At the time of study, ER was the only therapy available for drug refractory VT.

RESULTS

Only emergency ER, wall motion score less than 3 and Killip classification were significantly related to death from cardiac failure. The lack of correlation between emergency ER and variables of ER timing, VT less than 24 hours of ER or VT type implies that the need for emergency ER is also related to ventricular dysfunction. Multivariate analysis identified a group at particularly low risk of death with a specificity of 95%.

CONCLUSIONS

Patients at low risk of death after ER can be identified prospectively. In the implantable cardioverter defibrillator era, elective ER is best reserved for such patients. Emergency ER may still be justified in younger patients without comorbidity who will die of VT without it.

Perioperative and long-term results with mapping-guided subendocardial resection and left ventricular endoaneurysmorrhaphy

BACKGROUND

Surgical ablation of the arrhythmogenic focus in patients with life-threatening ventricular tachyarrhythmias can be curative. However, the surgical techniques have been plagued by a high perioperative mortality rate (averaging approximately 12%). Reconstruction of the left ventricle may reduce mortality.

METHODS AND RESULTS

Reconstruction of the left ventricle with a pericardial patch, or endoaneurysmorrhaphy, was performed with mapping-guided subendocardial resection for recurrent ventricular tachycardia in 25 patients over a 5-year period. Postoperatively, electrophysiological studies were conducted to assess the results of surgery, which were further evaluated during long-term follow-up with survival analyses. The study included 25 patients, 60 +/- 9 years of age, with coronary artery disease, discrete left ventricle aneurysms, and malignant ventricular tacharrhythmias. Left ventricular ejection fraction was 24 +/- 6% preoperatively. Left ventricular endocardial mapping, endocardial resection, and endoaneurysmorrhaphy were performed in all patients. There was no operative or postoperative (30-day) mortality. Postoperative ventricular tachycardia was induced in 2 of the 25 patients (8%); left ventricular function increased to 32 +/- 9% (range, 19% to 52%). At a mean follow-up of 37 +/- 16 months (range, 6 to 65 months), there had been 6 deaths, including 1 sudden cardiac death, 2 congestive heart failure deaths, and 3 noncardiac deaths. Analysis of multiple variables failed to identify predictors of postoperative inducibility, sudden cardiac death, cardiac death, or total mortality.

CONCLUSIONS

Endoaneurysmorrhaphy with a pericardial patch combined with mapping-guided subendocardial resection frequently cures recurrent ventricular tachycardia with low operative mortality and improvement of ventricular function. Long-term follow-up demonstrates low sudden cardiac death rates.

Anterior septal coronary artery infarction in the canine: a model of ventricular tachycardia with a subendocardial origin. Ablation and activation sequence mapping

BACKGROUND

In humans, chronic ventricular tachycardia (VT) is usually associated with myocardial infarcts that involve the interventricular septum. In an effort to more closely mimic the anatomic substrate that gives rise to chronic VT in humans, we developed a canine model of VT in which the anterior septal coronary artery was ligated. The site of earliest activation, the subsequent activation sequence, and the mechanism of VT associated with the resultant ventricular septal infarct was then evaluated to determine if this model accurately reflected the characteristics of human VT.

METHODS AND RESULTS

Seventeen dogs underwent occlusion-reperfusion ventricular septal infarcts. Four to 7 days later, electrophysiological studies were performed. VT was initiated by programmed electrical stimulation and terminated by pacing at a cycle length of 50% to 75% of the VT cycle length. Electrophysiological studies were performed using a 256-channel mapping system. A total of 15 VT morphologies were mapped in 9 animals. Fourteen of 15 morphologies had septal subendocardial sites of earliest activation and 1 had a septal midwall site of earliest activation. VT ablation was performed using a nitrous oxide cryoprobe and confirmed the site of earliest activation by subsequently rendering VT noninducible. Electrophysiological studies demonstrated four distinct VT activation sequences: (1) circular reentrant (n = 7), (2) concentric spread (n = 5), (3) figure-of-eight (n = 2), and (4) septal midwall (n = 1).

CONCLUSIONS

This canine model of ventricular septal infarction produces VTs with sites of earliest activation and activation sequences similar to those in humans. A reentrant mechanism as the basis of these arrhythmias is supported by the following observations: (1) all VT was initiated and terminated with programmed electrical stimulation; (2) VT activation sequences were consistent with reentry; and (3) precise interruption of the sequence terminated the VT and rendered it noninducible.

Reflections on definitive surgical treatment of postinfarction ventricular tachycardia

The past 15 years have witnessed a substantial commitment to the understanding and surgical cure of postinfarction ventricular tachycardia, and the results of treatment have steadily improved. However, outside influences have had a negative impact on the use of this modality. With the widespread availability of implantable defibrillators, this has become an attractive alternative therapy to the sometimes difficult definitive surgical treatment. Meanwhile, early thrombolytic therapy for the management of evolving myocardial infarctions has been found to create a postinfarction electrical substrate that does not appear to be arrhythmogenic. As a result, clinical efforts to develop and refine definitive ventricular tachycardia surgical treatments have all but ceased. The intent of this article is to review the events that took place in this apparently transient era.

Hemodynamic effects of radical left ventricular scar resection in patients with and without congestive heart failure

To evaluate the hemodynamic changes that occur following radical left ventricular scar resection we studied 40 patients (mean age, 59.2 years; 36 males) with complete hemodynamic evaluation preoperatively (preop) and 5 to 12 days postoperatively (postop). Severe congestive heart failure (CHF) was present in 15 patients, ventricular arrhythmias in 19, and angina in 19 patients preop. The operation consisted of extensive scar resection with complete myocardial revascularization (average 2.4 grafts per patient). Ten patients required intraaortic balloon pump assist for up to 8 days postop. Postoperative left ventricular ejection fraction (EF) was estimated with multiple gated acquisition scanning. A significant rise in heart rate was observed in the whole group of patients postop (P = 0.000). In the group of patients with CHF preop the EF was increased from 25.1 +/- 8.4% (mean +/- SD) preop to 30.9 +/- 11.2% postop (P = 0.003), the cardiac index was increased from 2.2 +/- 0.5 liters/min/m2 preop to 2.7 +/- 0.5 liters/min/m2 postop (P = 0.02), and the pulmonary artery wedge pressure was decreased from 22.0 +/- 7.7 mm Hg preop to 15.5 +/- 4.3 mm Hg postop (P = 0.005). In the patients without active CHF preop no improvement in the above hemodynamics was noted. In conclusion, radical left ventricular scar resection significantly increased EF and CI and decreased PAW in patients with preop CHF, whereas in the absence of CHF this procedure resulted in minimal hemodynamic changes.

Surgical treatment of arrhythmias

Surgical treatment of arrhythmias is often more expeditious and more cost-effective in the long run than pharmacologic therapy. In the past, surgical treatment of arrhythmias has been reserved for patients with disabling paroxysmal or incessant tachycardia refractory to medical management, severe life-threatening arrhythmia or aborted episodes of sudden death. However, tachyarrhythmias that are refractory to pharmacologic therapy because of drug inefficacy, noncompliance or limiting side effects are not uncommon. Although nonpharmacologic treatment of arrhythmias carries with it a one-time period of higher risk (i.e., when the patient undergoes surgery), it is curative and often preferable to the uncertainty and possibly higher cumulative risk associated with medical management.