Comparison of standard aneurysmectomy and aneurysmectomy with directed endocardial resection for the treatment of recurrent sustained ventricular tachycardia

Clinical intracardiac electrophysiologic testing: technique, diagnostic indications, and therapeutic uses

Clinical cardiac electrophysiologic testing has evolved rapidly since 1968, when the technique was first described. In an electrophysiologic study, electrode catheters are positioned within the heart to record electrical activity from the atrium, atrioventricular conduction tissue, and ventricle. Programmed stimulation is then performed, which involves pacing of the atrium or ventricle and introducing critically timed premature stimuli during sinus rhythm or paced rhythm. The use of programmed stimulation in conjunction with intracardiac recordings in electrophysiologic studies has facilitated the diagnosis of mechanisms of arrhythmias and the assessment of therapy. Electrophysiologic testing is useful in selected patients with sinus node dysfunction, conduction system disorders, supraventricular tachycardia, ventricular tachycardia, or ventricular fibrillation and in survivors of out-of-hospital cardiac arrest and patients with symptomatic but unsubstantiated rhythm disturbances. Therapeutic approaches that can be assessed by electrophysiologic testing include serial drug testing to determine the effectiveness of antiarrhythmic agents, antitachycardia pacing, the implantable defibrillator, transcatheter ablation, and electrophysiologically guided surgical procedures. In this review, we discuss the methods of electrophysiologic testing, its clinical applications in diagnosing the various cardiac rhythm disturbances, and its use in assessing various therapeutic modalities.

Ventricular tachycardia: historical perspective

Ventricular tachycardia is now diagnosed frequently in patients with organic heart disease. Although ventricular tachycardia was first demonstrated electrocardiographically 75 years ago, the natural history, fundamental mechanisms, and optimal management have remained elusive. Early observers commented on the rarity of occurrence and poor prognosis associated with this arrhythmia, yet with time, some patients with ventricular tachycardia were reported to survive for prolonged periods. Because of the sporadic nature of the arrhythmia and its variable prognosis, assessment of the efficacy of therapies has been difficult. A wide variety of treatments has been advocated with enthusiasm, but only a few have been consistently reported to be effective. Citation of historical data to claim benefit from new treatments should be viewed with caution.

Quantitative two-dimensional echocardiographic assessment of patients undergoing left ventricular aneurysmectomy

To evaluate the role of quantitative two-dimensional echocardiography (2DE) in the preoperative assessment of patients undergoing left ventricular (LV) aneurysmectomy, we identified 37 patients who were studied with 2DE 1 to 56 (mean 12.6) days prior to surgery. Diastolic (Dd) and systolic (Ds) minor-axis dimensions at the base were measured and fractional shortening (FS) was calculated. Global and basilar half ejection fraction (EF) as measured from right anterior oblique left ventriculograms. At follow-up (mean 17.9 months), 27 patients were alive and clinically improved (group A) and 10 patients either died or were symptomatically unimproved (group B). Basilar half EF was significantly greater among patients in group A (0.50 +/- 0.09) than in group B (0.37 +/- 0.10) (p less than 0.001). Echocardiographic FS provided the best separation between groups. Mean FS was 0.25 +/- 0.06 in group A and 0.15 +/- 0.04 in group B (p less than 0.001). All seven patients with FS less than 0.17 were in group B while 25 of 27 patients with FS greater than 0.17 were in group A (p less than 0.001). Considering all patients, basilar half EF and FS were highly correlated (r = 0.84).

The mechanisms of ventricular tachycardia in humans determined by intraoperative recording of the electrical activation sequence

We recorded ventricular activation sequence during ventricular tachycardia in 76 patients who underwent surgical therapy of refractory ventricular tachycardia. Ventricular tachycardia arose from a discrete site (focal origination) in 28 patients (37%) or resulted from reentry around scar (macroreentry) in 22 patients (29%). The mechanism responsible for ventricular tachycardia was not discernable in the remaining 26 patients (34%), usually because of inadequacy of activation data. We conclude: (1) although focal originating of ventricular tachycardia is common, more frequently the mechanism is either macroreentry or uncertain, as assessed by conventional recording techniques; thus, a search for the "site of earliest activation" during ventricular tachycardia frequently may fail to direct rationally the operative procedure; (2) conventional techniques for intraoperative study of electrical activation during ventricular tachycardia are inadequate.

Laser photoablation of pathological endocardium: in vitro findings suggesting a new approach to the surgical treatment of refractory arrhythmias and restrictive cardiomyopathy

In selected patients, malignant ventricular tachyarrhythmias have been successfully abolished by excision of subendocardial arrhythmogenic foci. Likewise, in certain patients in whom restrictive cardiomyopathy is due to endocardial thickening, endocardial resection has resulted in hemodynamic improvement. The present study was designed to explore the utility, in vitro, of laser photoablation of pathologically thickened endocardium. Endocardial photoablation was easily accomplished regardless of etiological or anatomical variations using either the focused beam of a carbon dioxide laser or argon laser light delivered through a 200-microns optical fiber. Photoablation of areas as large as 3.9 X 1.3 cm was performed within 40 seconds. The extent or depth of endocardial photoablation could be limited to 2 mm2 in area or 1 mm in depth using either form of laser therapy. These in vitro results suggest that either carbon dioxide or argon laser phototherapy can be successfully applied to the surgical treatment of refractory arrhythmias and restrictive cardiomyopathy. Advantages of laser photoablation include speed and precision. Furthermore, laser photoablation obviates the difficulty associated with conventional techniques in establishing tissue planes.

Staphylococcal abscess complicating endocardial aneurysmectomy

Subendocardial left ventricular aneurysmectomy relieved previously intractable ventricular tachycardia in a 68-year-old man with severe coronary artery disease. Staphylococcal septicemia developed postoperatively; an infected venoclysis site may have provided the portal of entry. Autopsy confirmed staphylococcal abscess at the epicardial aspect of the ventriculotomy, constituting the first reported case, to our knowledge, of this complication following endocardial surgery.

On-line epicardial mapping of intraoperative ventricular arrhythmias: initial clinical experience

An on-line automatic mapping system was developed for beat by beat display of epicardial activation during ventricular tachycardia induced at the time of cardiac surgery. A sock array of 110 button electrodes was used to record and display local activation on a video monitor at 8.3 ms intervals. On instant replay in slow motion, epicardial pacing sites were accurately localized to the nearest electrode. Local unipolar electrograms were also recorded, first from the sock array, then from an array of 16 transmural needle electrodes. The epicardial display was verified by retrospective manually derived maps using the recorded epicardial electrograms. In four patients with coronary artery disease and recurrent inducible ventricular tachycardia, earliest epicardial activation was located on slow motion replay within 1 minute. Subendocardial sites of early activation were located within 10 minutes by replay of electrograms from the needle array before ventriculotomy. Transmural and endocardial resection of these sites prevented inducibility of the tachycardia on postoperative electrophysiologic study in three of the four patients. There has been no clinical recurrence of ventricular tachycardia after 3 to 14 months of follow-up despite cessation of antiarrhythmic therapy in three of the patients. This technique has unique advantages over existing mapping methods. It provides beat by beat display of activation sequences so that clinical tachycardias that are short in duration or pleomorphic in configuration now become amenable to mapping. In addition, it markedly shortens total time on cardiopulmonary bypass.

Operative therapy for ventricular arrhythmia

The history of surgical attempts to control ventricular arrhythmia is reviewed and current methodology is presented in detail. The results of the various surgical approaches and future trends in the management of this troublesome condition are discussed.

Evaluation of the patient with sudden cardiac death

Sudden cardiac death is defined as death from natural causes that occurs within one hour of the patient's collapse. Public education programs and the proliferation of rapidly deployable community life-support teams have resulted in the ability to deliver emergency medical care to many patients who suffer a cardiac arrest and who otherwise would have died suddenly. This article reviews the diagnostic evaluation and therapeutic management of the patient who has survived a cardiac arrest.

Natural history of surgically treated ventricular aneurysm

Forty-one patients underwent resection of a postinfarction ventricular aneurysm. Thirty-seven of them had associated saphenous vein grafting procedures (average, 2.3 grafts per patient). Thirty-five patients sustained left ventricular dysfunction preoperatively. Forty patients were followed until death or for a minimum of five years (1 was lost to follow-up), and functional status was evaluated. Hospital mortality was 12%. Twenty-four patients survived five years or longer, and 20 patients were alive after a mean follow-up of 84 months. Eighty percent of the nonsurvivors died of atherosclerosis-related events. Forty-nine percent of the patients who survived the operation sustained severe atherosclerotic events postoperatively. Only 2 of 15 nonsurvivors ever regained functional status as judged by return to work. Twelve of the 20 long-term survivors returned to work. Of those patients less than 50 years old at operation, only 17% returned to work. Preoperative left ventricular function was a significant predictor of long-term functional results of aneurysmectomy and saphenous vein grafting. All patients remained at high risk for continued events related to atherosclerotic cardiovascular disease, and only 37% returned to full-time, preoperative work status. Return to productive status was especially disappointing in patients less than 50 years old.

The treatment of malignant ventricular arrhythmias with combined endocardial resection and implantation of the automatic defibrillator: preliminary report

Fourteen patients with refractory ventricular tachyarrhythmias were treated with combined endocardial resection and implantation of the automatic defibrillator. There were 11 men and 3 women with a mean age of 53 years (range, 41 to 58 years). All patients had coronary artery disease; the mean ejection fraction was 26%, and the mean number of cardiac arrests was 2.6. Programmed electrical stimulation induced sustained ventricular tachycardia in 13 patients and nonsustained ventricular tachycardia in 1. Operative endocardial mapping in the 13 patients with sustained ventricular tachycardia demonstrated a septal focus of early activation in 9 patients and a nonseptal site in 4. Following resection, sustained ventricular tachycardia could not be reinduced. There was 1 operative death. Programmed electrical stimulation performed one month after operation induced ventricular tachycardia in 5 patients, but tachycardia could not be induced in the other 8 survivors. The longest follow-up was 32 months; the average was 17 months. There were 2 late deaths. One patient died of myocardial infarction and 1 of pulmonary edema following a routine cholecystectomy. In another patient, late ventricular tachycardia developed but was automatically terminated by the implanted defibrillator. These results suggest that endocardial resection combined with implantation of the automatic defibrillator may offer the greatest protection yet available to patients with malignant ventricular tachyarrhythmias.

Subendocardial resection for refractory ventricular tachycardia: effects on ambulatory electrocardiogram, programmed stimulation and ejection fraction, and relation to outcome

The inducibility of ventricular tachycardia by programmed stimulation was correlated with ventricular ectopic activity on ambulatory electrocardiogram, ejection fraction and clinical outcome in 36 patients after endocardial resection for medically refractory ventricular tachycardia. Ventricular tachycardia was noninducible postoperatively in 25 patients and was inducible in 11. After administration of antiarrhythmic drugs, ventricular tachycardia could no longer be induced in four patients and remained inducible in the other seven patients. All 36 patients had postoperative and 20 had preoperative ambulatory electrocardiograms obtained while they were not receiving drug therapy. Pre- and postoperative ambulatory electrocardiograms did not differ in mean hourly ventricular premature depolarization frequency, Lown arrhythmia grade or change in grade (pre- vs. postoperative). The majority of postoperative patients had repetitive forms of ventricular arrhythmia postoperatively and there was no difference between patients with inducible and noninducible ventricular tachycardia in regard to Holter monitoring characteristics. There was no significant difference in postoperative ejection fraction between patients with inducible and noninducible ventricular tachycardia postoperatively. Ventricular tachycardia has recurred in 2 of 29 patients who had no inducible tachycardia at the time of hospital discharge and were followed up for a mean of 1 year; it has recurred in one of seven patients in whom it was still inducible at the time of hospital discharge and who were followed up for a mean of 7 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophysiologic studies in nonsustained ventricular tachycardia: relation to underlying heart disease

Electrophysiologic studies were performed in 83 patients with spontaneous episodes of nonsustained ventricular tachycardia (VT). The clinical arrhythmia was reproduced in 63% (in 42 patients by programmed stimulation and in 10 by isoproterenol infusion). In 15 patients sustained VT could be reproducibly induced by programmed stimulation. Inducibility was related to the associated heart diseases: programmed stimulation induced VT in 25 of 33 patients (75%) with coronary disease, 6 of 18 patients (33%) with cardiomyopathy (dilated in 16, hypertrophic nonobstructive in 2), in 4 of 8 patients (50%) with mitral valve prolapse and in 7 of 24 patients (29%) without structural heart disease. Isoproterenol infusion induced VT in no other patient with coronary artery disease, 1 other patient with mitral valve prolapse, 3 patients with cardiomyopathy, and in 6 of 24 patients without structural heart disease. Sustained VT was induced only in patients with structural heart disease, and correlated with the presence of left ventricular aneurysms: Sustained VT was induced in 9 of 13 patients with left ventricular aneurysms. The study demonstrates that electrophysiologic techniques can reproduce episodes of nonsustained VT in most patients with spontaneous arrhythmias. Some patients who demonstrate only nonsustained VT spontaneously have inducible, sustained VT, most often in the setting of coronary artery disease and left ventricular aneurysms.

Sustained ventricular tachyarrhythmias during the early postinfarction period: electrophysiologic findings and prognosis for survival

Forty patients with sustained tachycardia occurring 3 to 65 days after myocardial infarction underwent programmed ventricular stimulation within 3 months of the infarction. Patients were characterized clinically by a complicated initial 48 hours of hospitalization for their acute infarction (85% of study group). The development of bundle branch block in association with infarction occurred with an unusually high frequency (32%). Ventricular tachycardia similar in configuration to spontaneous arrhythmia was induced with programmed ventricular stimulation in 33 (83%) of the 40 patients. In 15 (45%) of these 33 patients, additional morphologically distinct ventricular tachycardia not seen clinically was initiated. The induction of ventricular tachycardia was not significantly related to the time after myocardial infarction at which spontaneous ventricular tachycardia was initially observed. Only 20 of the 40 patients are alive after a mean follow-up period of 20 +/- 15 months. Twelve of the 20 deaths were sudden cardiac deaths. Sixteen of the 33 patients with inducible ventricular tachycardia died; 8 of the 16 deaths were sudden. By comparison, four of the seven patients with no inducible ventricular tachycardia died (probability [p] = not significant), all suddenly. The mode of therapy did not influence subsequent survival. It appears that in patients with sustained ventricular tachycardia occurring more than 48 hours after a recent myocardial infarction, ventricular tachycardia similar to that clinically observed can usually be induced by programmed stimulation. In addition, multiple morphologically distinct ventricular tachycardias, some of which have not been previously observed, are frequently induced. Finally, the prognosis for survival is poor, regardless of inducibility or mode of therapy, and may in part be related to a changing arrhythmia substrate.

When is myocardial mapping clinically valuable?

All cardiac arrhythmias are either automatic or reentrant. Automatic arrhythmias occur in the periinfarction or perioperative period. Chronic, recurrent arrhythmias are typically reentrant. By definition, reentrant arrhythmias are inducible with programmed electrical stimulation. When a malignant cardiac arrhythmia is identified, the patient is taken to the electrophysiologic laboratory for study. Reentrant ventricular tachyarrhythmias are induced with programmed electrical stimulation. Pharmacologic suppression is guided by electrophysiologic testing. When antiarrhythmic suppression fails, surgical intervention may be an effective alternative. Endocardial catheter mapping before surgery may serve as an important guide to the surgeon. Myocardial mapping is clinically valuable only when all antiarrhythmic therapy has failed, and the patient is considered to be a candidate for surgical intervention. When surgical intervention is planned, we consider preoperative catheter mapping desirable and intraoperative electrophysiologic localization mandatory.

Treatment of cardiac arrhythmias in patients with acute myocardial infarction

Cardiac arrhythmias and conduction disturbances are commonly observed in patients with myocardial infarction. The available data suggest the administration of prophylactic lidocaine, either through a large intramuscular dose (300 mg), which is particularly suited for out-patient situations, or through intravenous loading doses followed by a constant lidocaine infusion. Patients with ventricular arrhythmia should be treated with direct-current countershock if hemodynamic deterioration is present. Drug therapy for patients with ventricular arrhythmias who are resistant to lidocaine include procainamide, bretylium, or intravenous amiodarone (experimental drug). Treatment of atrioventricular block in acute infarction depends on the site of atrioventricular block, the infarct location, and the hemodynamic status. Generally, atrioventricular block associated with inferior infarction and normal hemodynamic states generally does require insertion of a pacemaker. In contrast, patients with anterior myocardial infarction and Mobitz II or third degree atrioventricular block should be treated with emergent temporary insertion of a pacemaker. In addition, prophylactic pacing is clearly indicated for those with acute myocardial infarction complicated by the bifascicular block pattern of first degree atrioventricular block and new onset bundle branch block.

Relation between site of origin of ventricular tachycardia and relative left ventricular myocardial perfusion and wall motion

To assess the relation between the site of origin of ventricular tachycardia (VT) and relative myocardial perfusion and wall motion, 18 patients with a history of recurrent sustained VT underwent cardiac catheterization, invasive electrophysiologic study with endocardial mapping, and resting radionuclide ventriculography. In addition, 6 patients had exercise and redistribution thallium-201 scintigraphy, whereas the remaining 12 patients had resting thallium scans. The site of origin of VT (determined by catheter and intraoperative endocardial mapping) was correlated with relative myocardial perfusion (thallium) and left ventricular (LV) wall motion. All patients had significant (greater than 50% narrowing) coronary artery disease and 16 had LV aneurysms. Twenty sites of origin of VT (28 morphologies) were identified in these 18 patients. Of the 9 patients with multiple VT morphologies, the VT originated at disparate sites in 2 patients. All 18 patients had thallium defects at rest and 3 patients had additional reversible (ischemic) defects on exercise. Of the 20 sites of origin of VT, 16 were at the periphery of the thallium defect, 1 was adjacent to it, and 3 were in the center of it. In the 16 patients with LV aneurysm, there were 18 sites of origin: 15 at the border of the aneurysm, 1 adjacent to it, and 2 within it. The data suggest that in patients with VT and coronary artery disease the site of origin is usually the periphery of a resting thallium defect, and in patients with LV aneurysm the site is the border of the aneurysm.

Extended endocardial resection for the treatment of ventricular tachycardia and ventricular fibrillation

A total of 40 patients with drug-refractory, life-threatening cardiac rhythm disturbances--ventricular tachycardia in 23 patients and ventricular fibrillation in 17 patients--underwent extended endocardial resection (EER) of scar tissue. Scarring was due to myocardial infarction in 38 patients, to previous congenital heart operation in 1 patient, and to sarcoidosis of the heart in 1. The EER procedure was directed by epicardial and endocardial mapping data whenever possible, and was usually combined with revascularization, aneurysmectomy, or, in 5 patients, mitral valve replacement. Operative mortality was 10%, incident to poor preoperative ventricular function and hemorrhage secondary to previous cardiac surgical procedures. Thirty-three of the 36 survivors (92%) are free of arrhythmia at follow-up periods ranging from 3 to 36 months (mean, 12.5 months); the arrhythmia in the remaining 3 patients is now drug controlled. Thirty-three patients had postoperative electrophysiological studies, and in 30 (91%), the arrhythmia was no longer inducible. The results of surgical treatment for ventricular tachycardia and ventricular fibrillation were similar. The results also proved satisfactory whether the EER procedure was directed by visual observation or mapping.

Electrocardiographic changes following endocardial resection for ventricular tachycardia

The ECG changes resulting from endocardial resection, with or without aneurysmectomy and coronary artery bypass grafting (CABG), are reported in 82 patients. Angiographic and surgical features and peak creatine kinase (CK) levels are correlated with ECG findings. Twenty-three of 82 patients (28%) had the following ECG changes postoperatively: decreased ST segment elevation = 3 (4%), loss of R wave amplitude = 4 (5%), increased R wave amplitude = 5 (6%), new Q wave = 4 (4%), axis shift greater than or equal to 45 degrees = 6 (7%), and new bundle branch block = 6 (7%). Five of six new cases of bundle branch block were left bundle type and resulted from resection of the inferoposterobasal and contiguous septal endocardium. ECG anterior infarction, anterior aneurysm, and anteroseptal endocardial resection were associated with a significantly lower incidence of postoperative ECG changes. Aneurysmectomy and the performance of CABG were not significantly associated with postoperative ECG changes, but more bypass grafts per patient grafted appeared in the group with postoperative ECG changes, suggesting that coronary artery disease may be more severe in that group. Peak CK did not correlate with postoperative ECG findings. We conclude that ECG changes occur infrequently after endocardial resection and that the factors responsible are not clear, although severity of coronary artery disease may be contributory. Left bundle branch block is a significant complication of inferoposterobasal resection, but complete heart block appears not to be. The diagnosis of myocardial necrosis is difficult in these patients.

Long-term results of endocardial resection for sustained ventricular tachycardia in coronary disease patients

Sixty patients with recurrent sustained ventricular tachycardia (VT) refractory to medical therapy underwent subendocardial resection. There were 52 men and 8 women, ranging in age from 39 to 74 years, all of whom had coronary disease. Each patient had had a prior infarction 1 week to 11 years prior to surgery and 52 had left ventricular aneurysms. The mean ejection fraction was 27%. All 60 patients underwent endocardial resection with or without aneurysmectomy guided by intraoperative and/or catheter endocardial mapping. Thirty-seven endocardial resections were from the interventricular septum, 14 from the interoposterior free wall, and 16 were from the anteroapical and anterolateral free wall. There were five (8%) surgical deaths. The 55 survivors underwent programmed stimulation in the control state 28 days following the operation. VT was not inducible in 42 patients (group A) and was inducible in 13 patients (group B). The group B patients underwent drug testing and were discharged on the antiarrhythmic agent that made the VT noninducible or more difficult to induce. There have been only four recurrences in sustained VT with a follow-up of 19 +/- 11 months. There have also been nine late nonarrhythmic deaths. The actuarial survival curve predicted 62% survival at 40 months. We conclude that activation guided endocardial resection provides long-term effective therapy for drug-resistant ventricular tachycardia.

Surgery for ventricular tachycardia: efficacy of left ventricular aneurysm resection compared with operation guided by electrical activation mapping

Sixty-five patients underwent surgery for recurrent ventricular tachyarrhythmias. The 32 patients in group 1 underwent simple left ventricular aneurysm resection. The 33 patients in group 2 underwent myocardial resection or incision guided by intraoperative mapping of the electrical activation sequence. The clinical, hemodynamic and angiographic characteristics of the two groups were similar. Although actuarial survival in the two groups was similar through 24 months, late attrition in group 1 patients has left only 21 +/- 13% (+/- SEM) alive by life-table analysis at 94 months. Arrhythmia recurrence has been greater in group 1 than in group 2. In group 1, 50 +/- 9% of patients at risk at 3 months had recurrences by actuarial analysis. In group 2, only 13 +/- 6% at 1 month, 17 +/- 7% at 3 months and 29 +/- 9% at 24 months relapsed. Death was caused by ventricular tachyarrhythmias in 12 of the 17 patients (71%) who died in group 1, but only three of 12 (25%) who died in group 2. We conclude that surgery of the left ventricle, guided and modified by intraoperative mapping of the electrical activation sequence, frequently eliminates ventricular tachyarrhythmias and may be more effective than blind resection of left ventricular aneurysm.