The surgical treatment of ventricular tachycardia

A Hybrid Maze Procedure for Long-Standing Persistent Atrial Fibrillation

BACKGROUND

Catheter ablation (CA) for long-standing persistent atrial fibrillation (LSPAF) is suboptimal, and open surgical ablation, although more successful, is too invasive to be a first-line therapy. Less invasive hybrid procedures that combine thoracoscopic surgery (TS) with CA have been only marginally more successful for LSPAF than CA alone.

METHODS

Joint hybrid procedures for LSPAF are based on the assumption that AF surgery and CA procedures can be guided by intraoperative mapping. However, intraoperative mapping is not always dependable because of the transient nature of the sustaining reentrant drivers. The best results in patients with LSPAF have been attained with the non-guided, anatomy-based surgical Maze-III and Maze-IV procedures. Likewise, a staged TS/CA hybrid procedure that creates a combination of lesions that adhere to the concept of a Maze pattern, that is, a Hybrid Maze-IV procedure, should be more effective for LSPAF.

RESULTS

Initial TS includes all lesions of the Maze-IV procedure except the mitral line, coronary sinus lesion, and one right atrial lesion. Follow-up CA at 3 months includes touching up any incomplete TS lesions, a cavotricuspid isthmus lesion, and a mitral line/coronary sinus lesion in the 10% to 15% of patients with post-TS perimitral flutter. This combination of TS and CA lesions creates a complete Maze-IV procedure.

CONCLUSIONS

It is possible to create the complete lesion pattern of a Maze-IV procedure with a staged TS/CA hybrid procedure. The success of this Hybrid Maze procedure in patients with LSPAF should be the same as that attained with an open surgical Maze-IV procedure.

[Prevention and treatment of cardiac arrhythmia in patients with congenital heart defects: surgical aspects]

Catheter ablation procedures have become established over the years due to their effectiveness and low invasiveness and have changed the indications for surgical treatment. The main field of activity of cardiac surgery remains the treatment of patients with congenital heart defects which show arrhythmia and necessitate surgical treatment. The combination of surgical ablative measures with a good view of the site using modern ablation instruments, atrial reduction by tissue resection and correction of the defect with the resulting volume relief, bring the best conditions for a curative treatment of arrhythmia. The same applies to the treatment of ventricular tachycardia resulting from old scars and residual defects. Special attention should be given to patients who received a Fontan conversion. This operation is a unique opportunity to relieve volume which in turn reduces the atrial size and at the same time to take ablative measures to restore sinus rhythm. The results are promising with low mortality and morbidity, high efficiency and finally a clear improvement of the functional status of patients. In appropriate cases minimally invasive surgical procedures can help where pharmacological and catheter ablation therapies remain ineffective.

Argon laser ablation of malignant ventricular tachycardia associated with coronary artery disease

The long-term clinical efficacy and safety of intraoperative mapping-guided argon laser ablation alone or in conjunction with standard surgical methods were assessed in 20 consecutive patients with refractory sustained ventricular tachycardia (VT) or ventricular fibrillation. A 15-W argon ion gas laser was used and pulsed laser energy was delivered through a fiberoptic catheter delivery system. Pre- and intraoperative mapping was used to localize the arrhythmogenic tissue. Postoperative clinical, ambulatory electrocardiographic and electrophysiologic evaluations were performed before discharge and at 1 year of follow-up. Thirty-eight VT morphologies were mapped and ablated with laser energy alone (82%), combined laser ablation and mechanical resection (13%) or mechanical resection alone (5%). Concomitant coronary artery bypass surgery was performed in 15 patients and in 1 patient it was performed with mitral value replacement. Postoperative 30-day mortality was 5%. One patient (5%) required postoperative antiarrhythmic drug therapy, and all survivors had suppression of inducible sustained VT at discharge. Mean left ventricular ejection fraction increased from 34 +/- 12% preoperatively to 41 +/- 13% postoperatively (p = 0.001). Efficacy rates for ablation of VT sites associated with anterior myocardial infarction and inferior or posterior myocardial infarction were comparable (100 vs 96%, respectively, p greater than 0.2). At 1-year follow-up no sudden deaths had occurred and total survival rate was 90%. Intraoperative pulsed argon laser ablation alone or in conjunction with standard surgical techniques improves the efficacy of surgical ablation procedures for VT or ventricular fibrillation and reduces the need for additional postoperative antiarrhythmic drug or device therapy.

Surgery of ventricular tachycardia and ventricular fibrillation in patients with coronary artery disease and LV-aneurysms

In 26 patients with left ventricular aneurysm and ventricular tachycardia and/or ventricular fibrillation following myocardial infarction, coronary angiography, left ventriculography and electrophysiologic examination were performed preoperatively. Surgery in all cases consisted of aneurysmectomy and mapping-guided endocardial resection of the area found to be the arrhythmogenic center. Four patients died peroperatively or during the postoperative hospital stay. The 22 survivors were followed up for 3-48 (mean 22) months postoperatively. There were no late deaths. Repeated electrophysiologic studies were performed in 18 of the survivors. Freedom from ventricular tachycardia and fibrillation was achieved in 21 patients, 17 after surgery alone and four after combined surgical and medical treatment. The remaining patient still has ventricular tachycardia despite combined treatment.

Role of permanent pacemakers in the pharmacologic therapy of patients with reentrant tachyarrhythmias

Improved pacemaker technology has permitted application in more diverse groups of patients. A more recently described subset appears to be those with reentrant tachycardias treatable with antiarrhythmic drugs. Here, pacing offers the ability both to test the efficacy of a drug regimen and to provide adjunctive "fail-safe" therapy for those with episodic breakthrough. With the advent of more sophisticated devices, especially those with cardioversion/defibrillation capability, we anticipate a growing interest in these applications which will undoubtedly benefit patients.

Cardiac dysrhythmias in the acute setting: pathophysiology or anyone can understand cardiac dysrhythmias

Cardiac dysrhythmias are easy. Unlike the lung (which has formidable neuroendocrine, metabolic, and respiratory responsibilities), the heart is simple. It is an innervated muscular pump. A resting Purkinje or ventricular muscle cell membrane maintains a charge of about 90 millivolts. The five phases of a cardiac action potential are similar to the action potential in skeletal muscle, however, the cardiac action potential lasts a hundred times longer. When sodium specific "fast" channels and calcium specific "slow" channels open, positive ions rush into the myocardial cell, thus causing rapid membrane depolarization. In order to produce an action potential, some stimulus must decrease the membrane potential from -90 millivolts to "threshold" or -60 millivolts. Purkinje fibers do not have a stable phase for diastolic potential. These fibers continuously depolarize during diastole. Hypoxemia or hypokalemia may exacerbate this diastolic depolarization, thus promoting "hyperexcitability" or "automatic" ectopy. When myocardium is damaged, characteristically with myocardial ischemia, rapid conduction of cardiac impulses may be slowed dramatically. Very slow impulses may course through muscle such that by the time the activation wave front returns to the initiating site, this origin has had a chance to repolarize. This is the basis for re-entrant dysrhythmias. All cardiac dysrhythmias are automatic, re-entrant or both.

Sympathectomy in the treatment of angina and arrhythmias

Sympathectomy has been used as treatment for several different cardiac conditions. These include classic angina pectoris, Prinzmetal's angina, paroxysmal atrial tachycardia, ventricular tachycardia, and long QT syndrome. To understand the rationale of such treatment, the innervation of the human heart is reviewed with discussion of the cardiac plexus and coronary innervation. Results in published studies are summarized and discussed.

Histopathologic correlates of inducible ventricular tachycardia in two experimental canine models of myocardial infarction

Ventricular tachyarrhythmias are the leading cause of sudden cardiac death. Determination of the substrates conducive to the initiation of ventricular tachyarrhythmias remains an important clinical goal. The purpose of this study was to correlate electrophysiologic and histopathologic parameters conducive to the initiation of sustained ventricular tachycardia using programmed electrical stimulation in two canine models of myocardial infarction. Histopathologic correlates included: infarct pattern (heterogeneous vs. homogeneous morphology), distribution (viable epicardial or endocardial rim), and size. Twenty-one adult dogs were randomly divided into two groups: (1) 12 dogs underwent two-stage, 2-hour occlusion of the proximal left anterior descending coronary artery (LAD); and (2) nine animals had permanent, complete occlusion of the LAD with latex embolization. Using programmed ventricular pacing with two premature ventricular extrastimuli, initiation of ventricular tachycardia was attempted at both 1 and 2 weeks after infarction with the chest closed and opened each time. Electrophysiologic evaluation of the infarct type correlated significantly with the histologic morphology of the infarction (p less than 0.001), the presence of a viable epicardial rim was an extremely important discriminating variable for ability to induce sustained ventricular tachycardia (p = 0.04). The presence of an endocardial rim was not significant (p = 1.0). Infarct size alone was only marginally related to ventricular tachycardia inducibility (p = 0.08). Non-uniform infarcts were more conducive to the initiation of sustained ventricular tachycardia than homogeneous infarcts (p = 0.025). The presence of a large, non-uniform infarct was the best overall discrimination variable for inducibility (p = 0.0002). Thus, in these experimental models, specific infarct morphologies correlate significantly with susceptibility to inducible sustained ventricular tachyarrhythmias.

Effect of percutaneous transluminal coronary angioplasty on arrhythmias complicating angina

Four patients who had stenosis of a single major coronary artery which was treated by percutaneous transluminal coronary angioplasty are described. Three had exercise induced myocardial ischaemia complicated by ventricular tachycardia, fibrillation, and sinus bradycardia, respectively. Asystole developed in a fourth patient who had spontaneous chest pain. After successful percutaneous transluminal coronary angioplasty these arrhythmias did not recur spontaneously or on treadmill exercise testing. Percutaneous coronary angioplasty can be effective in preventing arrhythmias complicating acute myocardial ischaemia secondary to stenosis of a single major coronary artery.

Current status of coronary artery bypass grafting for coronary artery atherosclerosis

Coronary artery bypass grafting has now undergone 18 years of proven benefit in the treatment of myocardial ischemic disease. The technique of CABG has been further extended to other situations in which myocardial blood supply is threatened, such as cardiac trauma, aneurysms of coronary arteries, and congenital lesions. The emphasis in choosing CABG over medical therapy in 1985 should be preservation of myocardium at jeopardy of infarction as well as relief of angina. Proximal stenoses in vessels subserving viable muscle that is ischemic at rest or with minimal exercise should be treated with reperfusion by angioplasty or CABG to prevent further injury. After infarction occurs and ventricular function is impaired, CABG is also necessary to preserve remaining myocardium at jeopardy. Such an aggressive approach seems warranted with today's excellent surgical results. Long-term results have also improved, as more attention has been paid to saphenous vein graft preparation, use of mammary artery grafts, complete revascularization, use of antiplatelet agents, control of spasm, and identification of hypercoagulable states that may require sodium warfarin (Coumadin). Angioplasty of vein grafts and distal anastomoses also appears promising to help extend the results of initial CABG. Figure 1 is our recommended approach for the treatment of coronary atherosclerosis.

Current status of surgery for ventricular tachyarrhythmias

This article outlines the accepted histopathologic and electrophysiologic theories underlying the etiology of medically refractory ventricular tachyarrhythmias. It delineates the indications and techniques for the electrophysiologic study of the ventricle. Finally, the surgical procedures available as well as their indications and results are elucidated.

A safe approach to left ventriculotomy

Left ventriculotomy through an anatomically normal left ventricle is an increasingly frequent clinical necessity. In this regard, it is important to envision the epicardial projection of the papillary muscle in order to avoid injuring it. One should open the ventricle from the base (parallel to the left anterior descending or posterior descending coronary artery) and extend the incision apically while continuously palpating the papillary muscle.

Effects of oral amiodarone on left ventricular function in dogs: clinical implications for patients with life-threatening ventricular tachycardia

Twenty-four mongrel dogs were divided into two equal groups to determine the effects of orally administered amiodarone on left ventricular function. Measurements of left ventricular function included left ventricular contractility as denoted by maximum rate of rise of left ventricular pressure (dP/dtmax), cardiac index (CI), left ventricular stroke work index (LVSWI), and peripheral vascular resistance (PVR). Left ventricular function was measured in 6 of the 12 animals in Group 1 before and after 14 days of amiodarone administered orally; the remaining animals served as controls. The dP/dtmax was reduced from 2,855 to 1,291 mm Hg/sec (p less than 0.01), and LVSWI fell from 1.6 to 0.74 gm-m/beat/kg (p less than 0.05) in the 6 animals given amiodarone. The 12 animals in Group 2 underwent 30 minutes of ischemic arrest. Six animals in Group 2 underwent 30 minutes of ischemic arrest. Six animals were given amiodarone orally for 14 days prior to cardiopulmonary bypass and ischemic arrest; the other 6 served as controls. Before cardiopulmonary bypass, the dogs administered amiodarone had significantly greater depression of dP/dtmax (p less than 0.01) and LVSWI (p less than 0.05). Thirty minutes of ischemia produced significant depression of left ventricular function in all animals in Group 2. However, a significantly greater reduction in dP/dtmax and LVSWI occurred in those animals receiving amiodarone. Furthermore, 4 of the 6 dogs receiving amiodarone were unable to sustain sufficient cardiac output following cardiopulmonary bypass to permit long-term survival (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of regular, wide QRS tachycardia in infants and children

A regular wide QRS tachycardia was electrocardiographically documented in 32 patients aged 1 month to 18 years. The mechanisms of the tachycardia were evaluated using standard multicatheter electrophysiologic techniques. These mechanisms included (1) orthodromic reciprocating tachycardia with bundle branch aberration (seven patients), (2) antidromic reciprocating tachycardia using single (three patients), or multiple (three patients) atrioventricular connections (Kent bundles), (3) atrial flutter with ventricular preexcitation over accessory connections (eight patients), (4) reciprocating tachycardia using a nodoventricular connection (Mahaim fiber) (five patients), and (5) ventricular tachycardia (six patients). Regular side QRS tachycardias are not rare in pediatric patients. Their mechanisms can be quite complex, and electrocardiographic analysis with respect to QRS configuration, heart rate, or the presence or absence of ventriculoatrial dissociation is not sufficient for diagnostic purposes. Our results show that considerable understanding of the mechanism of regular, wide QRS tachycardias can be obtained by multicatheter electrophysiologic study. Understanding the mechanism is essential in order to make rational use of available therapeutic options.