Risk stratification and management of patients with recurrent ventricular tachycardia and other malignant ventricular arrhythmias

Clinical results are reviewed in 269 patients who underwent subendocardial resection for recurrent sustained ventricular tachycardia secondary to ischemic heart disease. Operative mortality is 15%. Factors increasing operative mortality rates are ejection fraction less than 20%, emergency operation, and history of previous heart operation. Use of amiodarone preoperatively does not alter operative risk. Clinical control of ventricular tachycardia is achieved in 93% of operative survivors. Two thirds of these patients do not need antiarrhythmic agents. Five-year actuarial survival is approximately 60%. Patient results with the automatic internal cardioverter defibrillator at the Hospital of the University of Pennsylvania and nationwide are also reviewed. As of June 1987, almost 1,500 patients had one or more devices implanted. Most patients had a prior documented cardiac arrest. Coronary artery disease is the cause of heart disease in over 70% of patients. Operative mortality is low (0.8-3.9%). Approximately 50% of patients have had therapeutic discharge of the device; however, asymptomatic discharge occurs in up to 45% of patients. Incidence of sudden death is 1.5% at 1 year and 5% at 5 years. Five-year actuarial survival is approximately 60%. Long-term mortality is primarily from heart failure.

Pericardial repair of endocardial defect following regional endocardial resection for ventricular tachycardia

Regional endocardial resection is the accepted surgical treatment for sustained monomorphic ventricular tachycardia. In patients requiring extensive endocardial resection, or with large aneurysms involving the interventricular septum, the resulting defect may result in weakened myocardium and, ultimately, ventricular septal defect or ventricular rupture. A new approach for repair of the resulting defect is proposed using an autogenous pericardial patch sutured to normal endocardium and included in the aneurysm repair. This technique was performed in six patients undergoing surgery for drug refractory ventricular tachycardia. All patients had large anterior left ventricular aneurysms with endocardial scar extending onto the septum. The large endocardial defect left after endocardial resection and aneurysmectomy was repaired with a pericardial patch. No intraoperative complications (e.g., suture line bleeding) were observed as a result of this technique. All patients are alive, and five of the six patients no longer have inducible ventricular tachycardia. An improvement in congestive heart failure symptoms at 1-9 months of follow-up was noted following surgery. We conclude that the pericardium can be safely used to cover endocardial defects resulting from regional endocardial resection for sustained ventricular tachycardia.

Surgery for left ventricular aneurysm. Early survival with and without endocardial resection

In the past 3 years, 86 patients had left ventricular aneurysms resected or plicated. Sixty-eight had recurrent sustained ventricular tachycardia as the indication for surgery and had preoperative and intraoperative electrophysiologic mapping. There were 14 hospital deaths (16%). Eight preoperative potential risk factors for early hospital mortality were analyzed by multivariate analysis. Only acute myocardial infarction within 30 days before surgery correlated with hospital death at the p less than 0.05 level. History of previous heart surgery and advanced New York Heart Association functional class were important risk factors at the p less than 0.1 level. Hospital mortality was 17.6% for patients who had intraoperative mapping and endocardial resection and 11.1% for the others. Patients who had aneurysm repair for ventricular tachycardia had a significantly higher incidence of low cardiac output early after surgery (p less than 0.025).

Surgical decisions in the management of sudden cardiac death and malignant ventricular arrhythmias. Subendocardial resection, the automatic internal defibrillator, or both

Subendocardial resection and implantation of an automatic implantable cardioverter/defibrillator are the current preferred treatments for the management of drug-resistant malignant ventricular arrhythmias and sudden cardiac death. We reviewed retrospectively the case histories of 269 patients who had subendocardial resection and 77 patients who had defibrillator implantation to define clinical characteristics of each group and compare operative and long-term results. All patients treated by subendocardial resection had recurrent sustained ventricular tachycardia as a result of a myocardial infarction. From the standpoint of arrhythmia substrate and cardiac disease, patients receiving the defibrillator were a more heterogeneous group. Forty-eight (62%) had coronary artery disease, 28 (36%) cardiomyopathy, and one patient had a primary electrical abnormality. Among patients receiving the defibrillator, 55% had sustained ventricular tachycardia and 45% polymorphic ventricular tachycardia or ventricular fibrillation. Overall ventricular function was similar in the two groups. Operative mortality rate was better in the group having defibrillator implantation (3% versus 15%). Complications related to the defibrillator device or implantation occurred in 46 (60%) patients, with asymptomatic shocks occurring in 35 patients (45%). Since the defibrillator was not designed to prevent arrhythmias, the arrhythmia-free survival rate was much better in the group having subendocardial resection (95% versus 44% at 3 years). Fewer patients treated by subendocardial resection required antiarrhythmic medications (33% versus 66%). The actuarial survival rate was similar in the two groups (approximately 60% at 4 years), with heart failure the most common cause of death. Thus both subendocardial resection and defibrillator implantation are highly effective in preventing sudden cardiac death. The choice of procedure depends on (1) arrhythmia diagnosis, (2) cardiac disease, and (3) intangible factors.

Endomyocardial fibrosis in the child

Endomyocardial fibrosis is a rare disease in children and has been mainly observed in tropical Africa, seldom in Europe. Its precise aetiology remains unknown. New surgical procedures have recently led to better survival. Four children, a 5 year old Swiss boy and 3 African girls, aged 12 to 14 years, were submitted with global heart failure class III to IV of the NYHA classification. Two patients had eosinophilia on admission. A third had a history of transient eosinophilia. The echocardiographic examination showed a very typical picture. In 3 patients (2 f and 1 m) both ventricles were involved; in one girl only the left ventricle. Decreased ventricular distensibility with impaired filling of the left and/or right ventricle was present in all. Diastolic pressures ranged between 24 and 35 mmHg; the systolic function was satisfactory in 3 children (ejection fraction [EF] of 44 to 61%) and severely decreased in the fourth (EF 10%). Three patients underwent endocardectomy: both ventricles in 1 case, only the left in 2 cases. Mitral valve repair by means of the Carpentier ring was done once, valve replacement once (Starr-Edwards prothesis). One child died; the 2 surviving patients showed a distinct improvement in their clinical state and are now in class II of the NYHA classification. Echocardiographic and catheter investigations show, however, persistence of the restrictive cardiomyopathy. Thus, surgical intervention must be considered a palliative procedure in these cases. The diagnosis can clearly be made nowadays with bidimensional and Doppler echocardiography.

Efficacy of cryosurgery alone for refractory monomorphic sustained ventricular tachycardia due to inferior wall infarction

The efficacy of cryosurgery alone was evaluated in 15 patients with refractory monomorphic sustained ventricular tachycardias related to inferior wall infarction. Patients were 64 +/- 9 (SD) years old and had a mean left ventricular ejection fraction of 39.2 +/- 11.2%. Thirty different tachycardias were mapped with the origin localized to the septum or inferior wall in 20 (67%), near the mitral valve anulus in 6 (20%) and at the base of the posterior papillary muscle in 4 (13%) tachycardias. Endocardial cryoablation of these sites was performed with 6 to 13 (mean 9.2 +/- 1.8) cryolesions per heart. No mitral valve replacement was performed. There was one postoperative death as a result of sepsis. Cryoablation abolished inducible ventricular tachycardia in 11 patients. Of the other three patients, the tachycardia in two was controlled with a single antiarrhythmic agent that had previously failed to suppress inducible ventricular tachycardia. Thus, clinical success was obtained in 13 (93%) of 14 patients. The remaining patient received an automatic implantable cardioverter defibrillator. Ejection fraction remained unchanged or improved after surgery in 14 patients (93%). There have been no late deaths, recurrence of sustained ventricular tachycardia or significant mitral regurgitation during a mean follow-up period of 19 +/- 7 months. These results compare quite favorably with those previously reported for subendocardial resection alone, and indicate that cryosurgery is highly effective, does not result in deterioration of left ventricular function and preserves mitral valve competence when cryoablation of the posterior papillary muscle is necessary.

Predictors of failure after endocardial resection for sustained ventricular tachycardia

This study was designed to identify characteristics that might be predictors of failure of surgical treatment alone (endocardial resection) for sustained ventricular tachycardia. Thirty-three consecutive patients with sustained ventricular tachycardia were studied by standard techniques preoperatively, intraoperatively, and 7 to 36 days postoperatively. Standard endocardial resection was guided by intraoperative mapping in all patients. Adjuvant cryoablation was used in areas that were not accessible to excision. Patients were divided into two groups on the basis of the results of the postoperative electrophysiologic study. Group I (14) were patients who still had ventricular tachycardia (failure) and Group II (19) were those who did not have ventricular tachycardia (success). On the basis of the postoperative electrophysiologic testing, the time from myocardial infarction to surgical treatment (less than 3 months) was a powerful predictor of failure of operation alone to prevent ventricular tachycardia (p less than 0.01). This may indicate a different mechanism of ventricular tachycardia in this group of patients. Another possible predictor of surgical failure was three-vessel disease. The site of origin of ventricular tachycardia, the use of cryoablation, the number of morphologies, and the amount of tissue resected were not significant predictors of success or failure. The result of the postoperative electrophysiologic study was also a strong prognostic predictor of subsequent arrhythmias.

Intermediate-term results of the endocardial surgical approach for anomalous atrioventricular bypass tracts

Between October 1974 and March 1, 1985, 26 patients with 29 anomalous AV bypass tracts underwent surgical treatment at the Medical Center of UAB, with follow-up from 1 to 14 years. Eleven of the patients underwent surgical correction of major associated cardiac anomalies. One patient had His bundle ablation, and 25 patients had direct surgical division of 28 bypass tracts with the use of an endocardial approach. Successful division was achieved in 27 (96%; confidence limits 88% to 99%) of 28 bypass tracts identified pre- and intraoperatively. There were no hospital deaths, but on formal follow-up there were three late deaths, all occurring in patients with major associated cardiac pathology. Neither preexcitation nor reciprocating tachycardia recurred, and functional status was excellent among patients without associated cardiac lesions. Because of the safety and, at least on intermediate-term follow-up, apparently curative nature of this operation (particularly for patients without other major cardiac pathology), surgical treatment is recommended for patients with bypass tracts having lethal potential, those with reciprocating tachycardia unresponsive to drugs, and to symptomatic patients facing many years of medications.

Surgical ablation of ventricular tachycardia with sequential map-guided subendocardial resection: electrophysiologic assessment and long-term follow-up

A new operative technique of sequential map-guided subendocardial resection (SER) was used in 45 consecutive patients for the treatment of sustained ventricular tachycardia due to coronary artery disease. This technique is characterized by map-guided SER or cryothermic ablation during normothermic cardiopulmonary bypass, followed by repeated sequences of programmed stimulation to assess adequacy of resection. The patients' mean age was 59 +/- 10 years and the mean left ventricular ejection fraction was 34 +/- 12%. Twenty-five (56%) patients had a history of myocardial infarction within the previous 2 months. After ventriculotomy, 34 patients (76%) had inducible monomorphic ventricular tachycardia. These patients underwent repeated sequences of ventricular tachycardia induction and mapping during normothermic bypass followed by successive SER or cryothermic ablation until sustained monomorphic ventricular tachycardia was no longer inducible. Twenty-seven patients had a total of 60 discrete, mappable tachycardias induced and seven patients had 10 discrete tachycardias that were too fast to accurately map. In the remaining 11 patients, no ventricular tachycardia was inducible after ventriculotomy and SER, which included all visually identifiable scar, was performed. The mean cardiopulmonary bypass time was 102 +/- 27 min. Forty-one of 45 patients (91%) survived to hospital discharge, and 35 of 41 patients (85%) had no inducible ventricular tachycardia at postoperative electrophysiologic evaluation performed in the absence of all antiarrhythmic drugs. The remaining six patients had no inducible ventricular tachycardia with drug therapy. All four operative nonsurvivors had refractory cardiac collapse preoperatively. Over 19 +/- 12 months of follow-up, there were four sudden cardiac deaths and no nonfatal recurrences of ventricular tachycardia. There were seven additional cardiac deaths. Actuarial cardiac survival was 0.57, and freedom from arrhythmic events was 0.76 at 42 months. Thus, in the absence of cardiogenic shock, the technique of sequential map-guided SER achieves: (1) a high operative survival with acceptable perfusion times, (2) excellent long-term arrhythmia control, and (3) survival comparable to that in patients with similar left ventricular function and no history of ventricular tachyarrhythmia.

Sequential endocardial resection for the surgical treatment of refractory ventricular tachycardia

The optimal surgical therapy for refractory ventricular tachycardia is controversial. The usual operation involves induction of tachycardia and endocardial mapping during normothermic cardiopulmonary bypass, followed by systemic hypothermia, aortic cross-clamping, and resection of the identified site of origin of the tachycardia. Our initial experience with this technique in 20 patients (mean age 60 years, mean ejection fraction 29%, mean number of failed antiarrhythmic drugs three) resulted in five (25%) surgical deaths, three caused by ventricular tachycardia and two by respiratory or heart failure. Electrophysiologic study showed that 11 of 15 survivors were free from ventricular tachycardia after operation, for a success rate in the survivors of 73%. Most failures occurred in patients with multiple tachycardia morphologies that were not eradicated by initial resection. Thereafter, the technique of sequential endocardial resection was used. After completion of endocardial mapping, directed normothermic endocardial resection is performed; more attempts to induce ventricular tachycardia are made and followed by further mapping and resection until tachycardia can no longer be induced. Fifty patients (mean age 59 years, mean ejection fraction 33%, mean number of failed antiarrhythmic drugs three) were treated by this method, with a mean of two resections per patient (range one to six). Mean perfusion time in the sequential resection group (101 +/- 28 minutes) was not significantly different from that of the earlier patients (101 +/- 40 minutes). There were four (8%) surgical deaths, one caused by persistent arrhythmia and three caused by respiratory or heart failure. Electrophysiologic study after operation showed that 40 of 46 survivors (87%) were free of ventricular tachycardia. Symptoms in the six with inducible tachycardia on postoperative electrophysiologic study were well controlled with medication. These data suggest that sequential endocardial resection guided by intraoperative mapping is a highly effective operative approach for patients with ventricular tachycardia.

Direct operations for the management of life-threatening ischemic ventricular tachycardia

Between June 1978 and 1986, 93 consecutive patients underwent electrophysiologically guided operations for life-threatening recurrent sustained ventricular tachycardia mostly associated with other surgical procedures, such as left ventricular resection (aneurysmectomy) and coronary artery bypass grafting.

DATA

Eighty-seven percent of the surviving patients were free of spontaneous ventricular tachycardia return or sudden death 1 year after the operation and 77% at 5 years. The instantaneous risk of ventricular tachycardia return was highest immediately after operation, declined rapidly, and by 2 weeks postoperatively had merged with the constant hazard phase, which persisted as long as the patients were observed. Endocardial resection, rather than encircling endocardial myotomy, increased the risk of spontaneous ventricular tachycardia return/sudden death. Survival rates, including hospital deaths, were 95% at 30 days, 89% at 1 year, and 70% at 5 years after operation. The most prevalent mode of death was heart failure. The absence of anterolateral left ventricular aneurysms and the use of more extended encircling incisional techniques for ventricular tachycardia ablation increased the risk of early and late death. Survival was particularly poor in that subset of patients in whom recurrent sustained ventricular tachycardia returned after operation; the most prevalent mode of death in this group was also progressive left ventricular failure. Inferences: (1) Complete and partial encircling endocardial myotomy incisions are the most effective surgical techniques for malignant ventricular tachycardia ablation. (2) Because of their adverse effects on left ventricular structure and function, the arrhythmogenic tissues have to be localized as precisely as possible, and the encompassing incisions should be kept as limited as possible. (3) The late return of ventricular tachycardia may be more related to a progressive ischemic left ventricular cardiomyopathy than to an inadequate operation.

Surgical options for treating ventricular tachyarrhythmia and sudden death

From 1981 to 1987, 62 patients with ventricular tachyarrhythmias and associated sudden death required treatment after unsuccessful initial medical therapy (51 patients) and previous surgical therapy (11 patients). Surgical options included direct revascularization (group I, 11 patients), endocardial resection (group II, 7 patients), automatic internal cardiac defibrillators (group III, 18 patients), and these combinations of operations: revascularization and endocardial resection (group IV, 18 patients), revascularization and insertion of automatic internal cardiac defibrillators (group V, 5 patients), and endocardial resection and insertion of cardiac defibrillator (group VI, 3 patients). Five underwent repeat revascularization (4) or endocardial resection (4) with mitral valve replacement (1) or papillary muscle reconstruction (2). The overall operative mortality of 8.1% (5/62) has been acceptable (2.8% or 1/36 for the simple procedures [groups I, II, and III] and 15.4% or 4/26 for the combined procedures [IV, V, and VI]; p less than 0.074). Operative risk factors included recent myocardial infarction (4/5 deaths) and depressed ejection fraction of 23% or less (5/5 deaths). These operative risks were highest in group IV and, thus, the highest mortality was in group IV (4/18 patients or 22%, p less than 0.022). Six late deaths (4 patients in group III) brought the overall survival rate to 82% or 51/62 patients at a mean follow-up of 30 months. Surgical treatment of sudden death ventricular tachyarrhythmias requires a planned, combined operative approach, since initial medical or surgical failures can occur. The optimal surgical approach requires complete revascularization, resection of the localized subendocardial arrhythmogenic focus, and ventricular reconstruction. An automatic defibrillator is a palliative alternative for less favorable surgical anatomy and for patients who are poor operative candidates for these combined or reoperative procedures.

Recent trends in the surgical treatment of endomyocardial fibrosis

Several modifications of the traditional treatment of endomyocardial fibrosis have been made based on a personal experience of 51 surgical cases and on the reports of others in the surgical literature during the last decade. Description of these techniques and the author's current concept of the pathological processes are reported herein.

Reconstruction of the mitral anulus

The mitral anulus was reconstructed with autologous pericardium in nine patients. Six patients had infective endocarditis with one or more abscesses in the anulus, and three had an iatrogenically damaged anulus. In patients with disruption of the mitral anulus limited to its posterior portion, a semicircular patch of pericardium was sutured directly to the endocardium of the left ventricle. In patients with multiple defects in the anulus, circumferential reconstruction of the mitral ring with pericardium was performed. In cases in which abscesses involved the central fibrous body, pericardium was used to reconstruct both the mitral anulus and the aortic root. Eight patients survived and have remained well for a mean of 8 months. There has been no prosthetic or patch dehiscence. All patients experienced substantial functional improvement. This experience indicates that the disrupted mitral anulus can be successfully reconstructed with autologous pericardium that is sutured directly to the endocardium of the left ventricle.

The role of surgery in the treatment of post-infarction ventricular tachycardia. A 5 year experience

The purpose of this report is to present a 5 year experience in electrophysiologically guided surgical treatment of post-infarction ventricular tachycardia (VT) in a consecutive series of 39 patients. In every case the arrhythmia was not responsive to pluripharmacological therapy. The diagnostic steps included preoperative endocardial, intraoperative epi- and endocardial mapping, automatically carried out when possible. Surgical techniques were: classic Guiraudon's encircling endocardial ventriculotomy (EEV), partial EEV, endocardial resection (ER), cryoablation or combined procedures. The hospital mortality was of 4 patients (10%). During the follow-up period (1-68 mo), 4 patients (11%) died of cardiac non-VT related causes. Among the survivors, 90% are in sinus rhythm. The authors consider electrophysiologically guided surgery a safe and reliable method for the treatment of post-infarction VT and suggest more extensive indications. They stress the importance of automatic mapping in pleomorphic and non-sustained VT, and the necessity of tailoring the surgical technique to the characteristics of each case.

Transcatheter desiccation of the canine left ventricle using radiofrequency energy: a pilot study

Catheter ablation of cardiac tissue by means of direct-current electrical energy is associated with several complications. We assessed the efficacy and safety of closed-chest catheter desiccation of the left ventricular myocardium with microbipolar radiofrequency (RF) energy (750 kHz) in five dogs. The unipolar configuration was used with RF energy delivered between the tip electrode of a standard No. 7F tripolar catheter in the left ventricle and an external patch electrode on the left lateral chest wall. A single application with different RF energy settings (100 J, 200 J, and 300 J) was delivered to three individual endocardial sites of the left ventricle. Ventricular tachycardia or fibrillation was not observed during energy application and 24 hours after ablation, as assessed by a Holter recording. There was no damage to the electrode catheter. Dogs were killed on the fifth day. Pathology showed well-delineated ovoid or round-shaped coagulation necrosis at the ablation sites. Microscopic findings consisted of circumscribed areas of necrosis surrounded by a zone of fibroblastic and mononuclear proliferation. In conclusion, catheter ablation of the ventricular myocardium with RF energy is an apparently safe procedure and can effectively produce discrete areas of injury without destruction of surrounding uninvolved myocardium. This method offers potential clinical utility for catheter ablation of refractory sustained ventricular tachycardia.

Laser-assisted endocardiectomy for refractory ventricular tachyarrhythmias: preliminary intraoperative experience

Previous in vitro investigations utilizing necropsy specimens have suggested a potential role for laser irradiation in the treatment of refractory ventricular tachyarrhythmias associated with pathologically thickened endocardium. In the patient described in the present report, findings of these previous in vitro studies were applied intraoperatively to a patient undergoing surgery for ischemic heart disease associated with ventricular tachyarrhythmias. Aneurysm resection and manual subendocardial resection were performed using standard techniques. Laser irradiation was used to ablate pathologically thickened endocardium involving the papillary muscle and thereby avoid mitral valve replacement. Postoperatively, there was no auscultatory evidence of mitral regurgitation, and ventricular tachycardia could not be induced by electrophysiologic provocative testing. This preliminary experience confirms that laser irradiation is both a feasible and potentially advantageous means of accomplishing endocardial debridement in patients undergoing arrhythmia-ablation procedures.

Long-term follow-up after surgical correction of Wolff-Parkinson-White syndrome

The long-term efficacy of surgical correction of Wolff-Parkinson-White syndrome was evaluated in 45 consecutive patients. Before surgery, 42 patients had reciprocating tachycardia and 12 had atrial fibrillation. The principal operative procedure was endocardial incision in 42 patients, endocardial cryoablation in 2 patients and epicardial cryoablation without dissection of the atrioventricular (AV) fat pad in 1 patient. Two patients had perioperative complications. One patient had bleeding that necessitated reoperation, and one had a right cerebral stroke with subsequent clearing of neurologic deficit. At postoperative electrophysiologic study, only the patient who underwent epicardial cryoablation had conduction over an accessory connection. Two others had intermittent delta waves in the early postoperative period but no accessory connection conduction at electrophysiologic study. During a mean follow-up of 3.1 years, the patient with ineffective cryoablation had recurrent orthodromic tachycardia, and one other patient had late recurrence of delta waves without arrhythmias. Four other patients had frequent palpitation, which was caused by premature ventricular complexes in three and sinus tachycardia in one. Seventeen patients had occasional "skipped beats" without recurrence of tachyarrhythmias. Twelve of 13 patients whose arrhythmias limited employment before surgery returned to work after surgery. By actuarial analysis at 1, 2 and 3 years, all patients were alive and 98% were free from tachyarrhythmias. Surgical correction of Wolff-Parkinson-White syndrome provides excellent long-term results with low morbidity. Patients who are disabled by arrhythmias return to work after successful surgery. Delta waves may persist or recur without return of arrhythmias. Minor postoperative episodes of palpitation are common and do not correlate with tachyarrhythmias.

Long-term efficacy of subendocardial resection in refractory ventricular tachycardia: relationship to site of arrhythmia origin

Subendocardial resection is performed in patients with ventricular tachycardia (VT), but its efficacy as related to the site of origin of VT is problematic. We analyzed the efficacy of subendocardial resection in 24 patients with coronary artery disease and VT. All patients underwent preoperative and intraoperative mapping before subendocardial resection. Postoperative electrophysiologic studies were performed in the drug-free state 7 to 14 days after subendocardial resection. Group 1 (n = 14) had anterior, septal, or lateral sites of origin, and Group 2 (n = 10) had inferior or posterior sites of origin. Localization of presystolic electrical activity during VT by preoperative and intraoperative mapping was comparable in both groups (100%). Resectability of the site of origin was higher in Group 1. Induction of VT during a postoperative electrophysiological study was higher in Group 2. Perioperative mortality was comparable. Postoperative antiarrhythmic therapy was instituted more frequently in Group 2. Actuarial survival analysis showed improved patient survival at one year after subendocardial resection for both groups. The efficacy of subendocardial resection is related to site of origin of VT: Subendocardial resection is less efficacious in VT with inferior or posterior sites of origin because of nonresectability of the arrhythmogenic area.

Improved results in the operative management of ventricular tachycardia related to inferior wall infarction. Importance of the annular isthmus

Ventricular tachycardia associated with inferior wall myocardial infarction has had a lower surgical cure rate with localized subendocardial resection than ventricular tachycardia related to anterior infarction. Some investigators have advocated visually directed extensive subendocardial resection, including resection of the papillary muscles and mitral valve replacement, even without documenting the origin of ventricular tachycardia at these sites. We have operated on 46 patients (43 men and three women) for ventricular tachycardia associated with inferior wall myocardial infarction. Thirty-one consecutive patients (Group I) had standard localized subendocardial resection. Two patients in this group had mitral valve replacement for mitral insufficiency. Fifteen consecutive recent patients (Group II) underwent subendocardial resection plus focal endocardial cryoablation (3 minutes at -70 degrees C) of the annular isthmus. The annular isthmus is defined as the ventricular muscle between the basal end of the ventriculotomy and the mitral valve anulus. In Group I there were four operative deaths (13%). Ventricular tachycardia was noninducible in 15 of 27 operative survivors (56%) at postoperative electrophysiologic studies. In Group II there was one operative death (7%) and 13 of 14 survivors (93%) had no inducible ventricular tachycardia at postoperative electrophysiologic studies (p less than 0.01 versus Group I). No Group II patient required mitral valve replacement. Six operative survivors in Group II had intraoperative activation maps consistent with macroreentry incorporating the annular isthmus. Group I and Group II were indistinguishable in terms of preoperative hemodynamics, number of coronary arteries diseased, or the presence of left ventricular aneurysm. These results suggest that subendocardial resection with additional cryoablation of the annular isthmus results in improved control of ventricular tachycardia in patients with ventricular tachycardia associated with inferior wall myocardial infarction. Mitral valve replacement is not required unless intrinsic mitral valve disease is present. These data also suggest that the annular isthmus is a critical component of the reentrant circuit in these tachycardias.

Perioperative and long-term results after electrophysiologically directed ventricular surgery for recurrent ventricular tachycardia

Thirty-six patients underwent ventricular aneurysmectomy and electrophysiologically directed endocardial resection for treatment of recurrent ventricular tachycardia refractory to antiarrhythmic drug therapy. The surgical mortality rate was 17% and all 30 patients discharged from the hospital were alive at the end of the follow-up period (range 6 to 54 months), yielding a cumulative projected survival rate of 83% by actuarial analysis. Poor systolic function of the nonaneurysmal ventricular segments was the strongest and the only independent predictor of operative mortality among the clinical, hemodynamic, angiographic and electrophysiologic variables analyzed by stepwise logistic regression. Ventricular tachycardia recurred early in four of the six patients in whom the endocardial resection was limited to a small area for technical reasons. Twelve patients, including 10 with sustained ventricular tachycardia still inducible by postsurgical programmed electrical stimulation, were discharged receiving antiarrhythmic drugs that had been tried unsuccessfully before surgery. During a mean follow-up period of 25 +/- 15 months, nonfatal sustained ventricular tachycardia recurred in two patients after discharge. Inadequate endocardial resection was a significant predictor of arrhythmia recurrence.

Thermal effects of laser and electrical discharge on cardiovascular tissue: implications for coronary artery recanalization and endocardial ablation

To determine the thermal responses of cardiovascular tissues to laser and electrical ablation, and to characterize the effects of different superfusing media and temperatures on target tissue temperatures and resulting extent of tissue injury, 184 laser and 15 electrical discharges were delivered to segments of human and canine aorta and canine ventricular endocardium. Tissue temperatures were measured 2 mm from the point of contact of laser fiber tip and tissue. When superfusing media consisted of whole blood or plasma at room temperature, a standard 40 J laser discharge caused peak arterial temperatures to rise 29.2 +/- 1.6 degrees C and 30 +/- 1.4 degrees C, respectively; however, tissue cooling was significantly slower in blood than in plasma. When saline solution was superfused, tissue temperatures rose by 11.4 +/- 2.2 degrees C, and tissue cooling occurred significantly faster than with either plasma or blood. The dimensions of the resulting aortic lesions were larger when blood (1.69 +/- 0.26 mm) was superfused than when plasma (1.39 +/- 0.04 mm) or saline (0.77 +/- 0.13 mm) was superfused (p less than 0.0001). Similar findings were observed with ventricular endocardium using blood or saline as the superfusing medium. In arterial tissue, superfusion with cold blood or saline solution resulted in lower peak temperature elevations (22 +/- 3.8 degrees C and 13.5 +/- 1.3 degrees C, respectively) and faster tissue cooling after laser discharge. Corresponding aortic lesion sizes were significantly smaller (1.4 +/- 0.03 and 0.5 +/- 0.02 mm, respectively) than when blood or saline medium was superfused at room temperature (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Resection of scarred papillary muscles improves outcome after surgery for ventricular tachycardia

Papillary muscle scarring is encountered frequently during operations for sustained ventricular tachycardia (VT). Indications for excision of the papillary muscle scar and mitral valve replacement (MVR) are controversial. The findings in 46 consecutive patients undergoing operative electrophysiologic map-directed endocardial resections for VT were reviewed. There was papillary muscle scarring in 15 patients (average age: 59 years; sex: 11 male, 4 female; average ejection fraction: 31 +/- 14%). Eleven patients had a VT with the site of origin on a scarred papillary muscle; four had another VT site of origin. Six patients underwent papillary muscle scar resection (5 with MVR); six underwent papillary muscle cryotherapy (-60 C X 2 min); and three had neither papillary muscle resection nor MVR. All six patients with papillary muscle resection +/- MVR are alive and free of arrhythmia after 14.3 +/- 7.6 months of follow-up. Five of six patients treated by papillary muscle cryotherapy alone manifested spontaneous (4 patients) or inducible (1 patient) VT during early postoperative evaluation. Two of the three patients with untreated papillary muscle scarring developed late complications requiring reoperation. One patient developed mitral regurgitation requiring MVR 5 months later. The other developed a previously undocumented VT 2 years after operation. Significant papillary muscle scarring visualized at the time of operation for arrhythmia is an indication for resection of the scar and the papillary muscle, even if this necessitates MVR. In this series, attempts to preserve the papillary muscle, by incomplete resection of the scar or by cryotherapy, resulted in a high failure rate owing to recurrent VT or mitral regurgitation.

Double tachycardia following surgery for recurrent ventricular arrhythmias

Simultaneous accelerated "junctional" rhythm and atrial flutter were observed postoperatively in a patient who had undergone electrophysiologic surgery for recurrent ventricular fibrillation. Digitalis toxicity was excluded, based on the low serum level of the drug and on the recurrence of the tachycardia after withdrawal of digitalis. While atrial flutter probably represented a postoperative recurrence of a clinically occurring arrhythmia, the accelerated "junctional" rhythm at unusually fast rates most likely developed as a consequence of a cryolesion applied to the ventricular septum as part of the surgical treatment. Phenytoin proved effective in suppressing this "junctional" tachycardia.

Surgical ablation of ventricular tachycardia: improved results with a map-directed regional approach

To determine whether a regional approach to surgery for ventricular tachycardia would improve on the results of previously reported methods of endocardial resection, an analysis was performed of our surgical experience over a 5 year period. Of 46 consecutive patients operated on for recurrent sustained ventricular tachycardia or ventricular fibrillation, 39 patients with ischemic heart disease underwent subendocardial resection and/or cryoablation. The mean age of the patients was 61 +/- 8 (SD) years, the mean left ventricular ejection fraction was 32 +/- 11%, and the mean number of ineffective antiarrhythmic drugs was 3.8 +/- 1.2 per patient. In 35 of 39 patients in whom mapping data were obtainable, 56 (86%) tachycardias had earliest sites of activation in the left ventricle and nine (14%) had earliest sites in the right ventricle. Ten patients had 14 tachycardias (21%) mapped to areas outside visible dense scar. Of these 35 patients, 10 underwent localized subendocardial resection and 25 underwent a regional procedure in which all areas activated before the surface QRS during ventricular tachycardia were excised and/or cryoablated. In the operative survivors of electrophysiologically guided surgery, three of eight (38%) patients with the localized and one of 24 (4%) patients who underwent the regional procedure had recurrence of ventricular tachycardia during a follow-up period of 1 to 59 (mean 22 +/- 17) months (p = .04). The favorable outcome of regional surgery was not influenced by the presence of multiple morphologies in 54%, disparate sites of origin in 29%, or inferior wall foci in 46% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Indications for different modes of surgical therapy in medically refractory ventricular arrhythmias

Fifty-one adult patients were referred for surgical treatment during the time period from July 1980 to November 1985. The average age was 59 +/- 6 years (19-70 years). All patients had symptomatic ventricular tachycardia that was refractory to standard or experimental drug therapy. On the basis of patient condition, site of arrhythmia, ventricular function, and extent of coronary disease, 21 patients were classed as good risk (GR) while 30 patients were thought to represent a poor surgical risk (PR). Thirty-two patients (15 GR, 17 PR) underwent electrophysiologic guided endocardial resection of arrhythmic foci. The hospital mortality was 12% (4/32), and two additional patients died late. All deaths were in poor risk patients. Recurrent arrhythmia was the primary cause of death in only one patient. Nineteen patients have required automatic internal cardioverter defibrillation (AICD) or chronic burst pacing (BP) with an implantable radiofrequency stimulator, with no operative mortality. AICD implantation was chosen for 13 drug refractory patients who were either poor surgical risk and/or had a tachycardia rate above 130 beats/minute with multiple scars or a multifocal tachycardia. Six additional patients who had tachycardia less than 130 beats/minute and whose arrhythmia could be safely terminated with BP had radiofrequency stimulator implantation. The one late death in this group was in a medically noncompliant patient. On the basis of this experience, we feel that map-guided endocardial resection should be offered to all good risk patients with a single scar and unifocal tachycardia who are refractory to medical treatment. This operation should be considered in all patients who have frequent, life-threatening attacks of tachycardia of any sort on maximum drug therapy. The remainder can be well managed with an AICD if their tachycardia rate is greater than 130 beats/minute or with BP using a radiofrequency stimulator.

Ventricular tachycardia in post-myocardial infarction patients. Results of surgical therapy

This report addresses the problems related to surgical treatment of post-infarction ventricular tachycardia (VT) and is based on a 5 year experience of 36 consecutive patients. In every case the arrhythmia was unresponsive to pharmacological therapy. All patients were operated on after the completion of a diagnostic protocol including preoperative endocardial, intra-operative epi-endocardial mapping, the latter performed automatically when possible. Surgical techniques were: classical Guiraudon's encircling endocardial ventriculotomy (EEV); partial EEV, endocardial resection (ER); cryoablation or a combination of these procedures. The in-hospital mortality (30 days) was 8.3% (3 patients). During the follow-up period (1-68 months), 3 patients (9%) died of cardiac but not VT related causes. Of the survivors, 92% are VT-free. We consider electrophysiologically guided surgery a safe and reliable method for the treatment of post-infarction VT and suggest its more extensive use. We stress the importance of automatic mapping in pleomorphic and non-sustained VT, and the necessity of tailoring the surgical technique to the characteristics of each case.

Endocardial excision versus encircling endocardial ventriculotomy. A comparison of effects on ventricular structure and function

Although endocardial excision and encircling endocardial ventriculotomy are being performed in patients with extensive triple-vessel disease and compromised ventricular function, long-term effects of the operative intervention on structure and function of the left ventricle have not been determined. These procedures were performed in healthy dogs in three groups: control (ventriculotomy alone), endocardial excision, and encircling endocardial ventriculotomy (five dogs per group). Six weeks later, through a left thoracotomy, an arterial line, left atrial line, and Swan-Ganz catheter were inserted. Cardiac output measurements permitted calculation of left ventricular stroke work index, and gated nuclear ventriculograms permitted calculation of left ventricular volume indices. Myocardial performance (stroke work index/end-diastolic volume index relation), systolic elastance (systolic blood pressure/end-systolic volume index relation) and diastolic pressure-volume relationship (left atrial pressure/end-diastolic volume index relation) were determined from volume loading studies. In the endocardial excision group, the left atrial pressures were increased at similar end-diastolic volumes (p less than 0.05 by performance and systolic elastance were similar in the three groups. On completion of hemodynamic studies, the hearts were excised. Gross and light microscopic examination showed that the inner layer of myocardium was scarred in the area of intervention after both endocardial excision and encircling endocardial ventriculotomy. In neither group was there significant morphologic change elsewhere in the myocardium. Both endocardial excision and encircling endocardial ventriculotomy have little effect on long-term structure and function when performed in healthy canine hearts.

Intrathoracic surgery for retained endocardial electrodes

Intrathoracic surgery for retained endocardial electrodes was performed in 12 patients; the indication for electrode removal was Staphylococcus aureus or epidermidis infection in 11 patients and malfunction in one patient. Two operations had to be performed on emergency basis. One was carried out because of myocardial rupture and cardiac tamponade after a tightly fixed electrode lead had been pulled out. The other patient was operated on because of ventricular arrhythmia arising from a malfunctioning lead which had slipped back completely after transsection into the right ventricle. Ten patients underwent elective surgery; cardiopulmonary bypass was needed in 6 of these. In one case a mitral prosthesis was replaced because of infection. Radical treatment is recommended for pacemaker infections and the removal of electrodes should be considered even if intrathoracic surgery is required.

Endocardial photoablation by excimer laser

A xenon-chlorine excimer laser was used to irradiate normal endocardium of fresh sheep and pig hearts as well as unfixed human endocardial scar. Forty pulses of 370 J and 35 ns each resulted in penetration of up to 12 mm in normal tissue and only 3.5 mm in scarred endocardium. Dosimetry indicated that the volume of vaporized scarred tissue was 1/10th that of normal endocardium (0.19 to 0.40 versus 1.35 to 3.22 mm3/J). Ultrastructurally, there was a sharp demarcation of only 10 mu between the region of injury and normal myocardium, with little evidence of heat injury. The high power and short duration of these lasers coupled with the lack of a boundary zone of injury suggest that excimers may be an ideal tool for arrhythmia ablation.

Treatment of malignant ventricular arrhythmias with endocardial resection and implantation of the automatic cardioverter-defibrillator

Although ventricular resection guided by endocardial mapping has been a successful treatment for drug-refractory ventricular arrhythmias, 20 to 30 percent of patients still have postoperative sustained ventricular tachycardia or sudden death. To improve the outcome of the procedure, we implanted an automatic cardioverter-defibrillator in conjunction with endocardial resection in 28 patients, all of whom had had previous myocardial infarctions and between one and five cardiac arrests. There were three perioperative deaths. During follow-up of 8 to 51 months (mean, 25), 4 of the 25 survivors had recurrences of hypotensive ventricular tachycardia, which in all instances were automatically terminated by the implanted device. One patient, whose automatic cardioverter-defibrillator was not functional, died suddenly. We conclude that patients undergoing mapping-directed endocardial resection can be provided with additional protection against recurrent ventricular tachyarrhythmias or sudden death by implantation of an automatic cardioverter-defibrillator.

Medical and surgical treatment of sustained and recurrent post-infarction ventricular tachycardia

Over a five-year period 57 patients (pts) with sustained, recurrent, post-infarction ventricular tachycardia (VT) refractory to conventional antiarrhythmic treatment were evaluated. In 28 (49%) pts VT was controlled by amiodarone (A) in a dose of 3000 mg week-1. During long-term follow-up 5/28 (18%) pts died; no severe side-effects were observed with this dosage. In 17 of the 29 pts not controlled by this regimen, the dosage of A was increased to 6000-8000 mg week-1; short-term control of VT was achieved in 9/17 (53%) pts, but over a long-term follow-up 5/9 (56%) died and severe side-effects (11% pulmonary fibrosis and 11% hepatitis) occurred in 22%. Twenty pts, resistant to a low (12 pts) or high (8 pts) doses of A, underwent map-guided surgical treatment. In conclusion A is superior to conventional drugs in the treatment of sustained, recurrent, post-infarction VT, but when high doses are necessary to prevent VT, long-term results are poor and severe side-effects frequent. In pts refractory to standard doses of A, map-guided surgery is the treatment of choice.

Extended subendocardial resection. A surgical approach to ventricular tachyarrhythmias that cannot be mapped intraoperatively

The optimal surgical management of patients with sustained, uniform-morphology ventricular tachycardia is endocardial activation sequence mapping during ventricular tachycardia and directed resection and/or cryoablation of the involved endocardium. The results of these procedures are superior to those obtained with nondirected aneurysmectomy. The optimal operative procedure when stable uniform ventricular tachycardia cannot be induced intraoperatively is uncertain. Between April, 1982, and April, 1984, intraoperative endocardial mapping was attempted on 33 patients with prior ventricular tachycardia. There were six perioperative deaths. Completely satisfactory intraoperative electrophysiologic maps were obtained in only 17 of the remaining 27 patients (63%). In 10 of these 27 patients, stable ventricular tachycardia could not be induced in the operating room, and satisfactory mapping thus could not be performed. In the first three of these 10 patients, limited subendocardial resection was performed either in regions with fractionated activity during sinus rhythm (two patients) or in regions suggested by preoperative catheter mapping (one patient). Ventricular tachycardia recurred postoperatively in two of these three patients. In the next seven patients, all visible endocardial scar around the border of the aneurysm was resected. Clinical ventricular tachycardia could not be induced at postoperative electrophysiologic study and has not recurred in these seven patients. These results suggest that complete endocardial resection provides an acceptable operative approach when intraoperative electrophysiologic mapping is not satisfactory.

Endocardectomy for the surgical treatment of endocardial fibrosis of the left ventricle

Two patients with endomyocardial fibrosis of the left ventricle were treated by endocardectomy plus mitral valve replacement. In both cases the results of surgery were satisfactory. No consequences related to eosinophilia, which was present before operation in one of them, were noted. The poor prognosis of this progressive disease and the inefficiency of medical treatment compared with the good surgical results already reported from various centres encourage early operation for all patients with endomyocardial fibrosis who have symptoms. Because of the pathophysiology of the disease, endocardectomy should be attempted in all cases and anti-coagulant treatment continued for life.

Cardiac surgical techniques for treating intractable ventricular tachyarrhythmias

Recurrent, sustained ventricular tachyarrhythmias unresponsive to medical therapy are associated with a one-year mortality of 70 to 85%. Patients who are susceptible to these reentrant arrhythmias usually have a history of previous myocardial infarction or chronic myocardial ischemic disease. More specifically, these patients demonstrate both anatomic and electrophysiologic derangements. Experimental work suggests that regions of non-uniform damage render the ventricle more susceptible to ventricular tachyarrhythmias; even relatively large areas of homogeneous myocardial ischemic damage may not display the same susceptibility to these arrhythmias. Surgical techniques are being devised to treat patients with ventricular tachyarrhythmias refractory to medical management. These have provided control of arrhythmias in patients whose disease was previously resistant to all medical treatment. The evolving surgical therapies presently employed share either of two pathophysiologic consequences which render them successful: the homogeneous ablation of previous heterogeneous myocardial ischemic damage or the delimiting of an arrhythmogenic focus by excluding conduction to surrounding myocardium. Finally, antitachycardia and defibrillating devices have also been developed to facilitate the management of patients not controlled satisfactorily with either conventional or investigative drugs. All physicians will need to be familiar with these devices.

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.

Activation mapping in patients with coronary artery disease with multiple ventricular tachycardia configurations: occurrence and therapeutic implications of widely separate apparent sites of origin

Catheter or intraoperative activation mapping studies, or both, were performed in 17 patients with coronary artery disease with two to four distinct configurations of ventricular tachycardia, resistant to a mean of 12.1 +/- 6.0 antiarrhythmic drug trials per patient. Mapping studies were performed to guide anticipated surgical ablation of arrhythmias. Activation map data were adequate to determine sites of origin of 30 (64%) of 47 observed tachycardia configurations. These 30 ventricular tachycardias (26 observed clinically) were mapped to 22 separate endocardial sites of origin. Sites of origin of distinct tachycardias were identical or closely adjacent (within 3 cm) in six patients and widely separate (greater than or equal to 4 cm) in eight patients (47% of the group). Activation maps were not adequate to determine sites of origin of 17 (36%) of the 47 tachycardias, including all configurations in three patients. Fifteen patients underwent surgery for control of ventricular tachycardia: aggressive, map-guided endocardial resection (mean 26.5 +/- 14.2 cm2) in 12 patients with identified sites of tachycardia origin and extensive resection of visible endocardial scar (2 patients) or encircling endocardial ventriculotomy (1 patient) in those in whom the sites of origin of all clinical tachycardias remained undetermined. Two inoperable patients were treated with amiodarone. During postoperative electrophysiologic tests (11 of 13 surgical survivors), ventricular tachyarrhythmias were initially uninducible in only 4 of 11 patients. However, in two patients only nonclinical arrhythmias (ventricular flutter) were induced. Six (21%) of 29 clinical tachycardias whose sites of origin were either not determined or not resected (right septum or papillary muscle) remained inducible in five patients. Using previously ineffective antiarrhythmic drugs, initially inducible arrhythmias became uninducible (two patients), or harder to induce than preoperatively (five patients). As a result of surgical resections alone or in combination with previously ineffective drugs (and amiodarone in two inoperable patients), there were no recurrences of ventricular tachycardia in 14 (93%) of 15 patients discharged during 19.0 +/- 14.3 months of follow-up study. Thus, activation mapping may commonly reveal separate apparent sites of origin for clinically observed, morphologically distinct, highly drug-refractory ventricular tachycardias in patients with coronary artery disease with multiple tachycardia configurations. Extensive surgical resection of identified sites of origin may be required to ablate arrhythmias in these patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Subendocardial resection for sustained ventricular tachycardia in the early period after acute myocardial infarction

One hundred nineteen patients with drug-refractory ventricular tachycardia (VT) underwent mapping-guided subendocardial resection for control of their arrhythmias from 3 weeks to 10 years after acute myocardial infarction (AMI). Patients were separated into 2 groups: those treated early (within 4 months, group I) and those treated later (after 1 year, group II) after AMI. There were 32 patients in group I and 72 patients in group II. Both groups of patients had similar clinical, angiographic and hemodynamic characteristics. Patients in group I had VT with a shorter mean cycle length than patients in group II (322 +/- 71 vs 349 +/- 88 ms, p less than 0.05). The groups did not differ with respect to operative mortality (12% vs 7%), late mortality (31% vs 33%, mean follow-up 23 months), or frequency with which subendocardial resection without any adjunctive therapy prevented postoperative spontaneous or inducible VT (21% vs 34%). Group I was further separated into patients who underwent subendocardial resection within 1 month of AMI (n = 7) and those who underwent subendocardial resection with 2 months of AMI (n = 14). Although patients in group I were characterized by having more spontaneous morphologically distinct tachycardias, their operative mortality, total mortality and surgical success rates were comparable to those of patients in group II.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment and treatment of life-threatening ventricular arrhythmias: the role of programmed electrical stimulation, intraoperative mapping, and endocardial resection

Increasing numbers of patients have survived one or more episodes of life-threatening VT or VF. This is largely due to more widespread training in cardiopulmonary resuscitation to the lay public, the advent of mobile and hospital coronary care units with improved survival from myocardial infarction, and aggressive treatment of rhythm disturbances. During the past decade, new techniques in the assessment and treatment of VT and VF have been introduced. These include PES, intraoperative mapping, and endocardial resection. As the use of these techniques becomes more widespread, nurses must expand their knowledge base to include an understanding of their indications and applications so that they may effectively contribute to the emotional and physiologic support of patients undergoing such procedures.

Surgical management of refractory ventricular arrhythmias in patients with prior inferior myocardial infarction. A preliminary report

Most reports of operations for ventricular arrhythmia have dealt with patients with anterior myocardial infarction. Patients with previous remote inferior myocardial infarction and recurrent ventricular tachycardia or fibrillation are a difficult subset of patients to treat with surgical ablative procedures. Over a 2 year period, 11 patients with prior inferior myocardial infarction and drug-refractory ventricular tachycardia or fibrillation underwent elective operation to control the arrhythmia. Five patients had monomorphic ventricular tachycardia. Three of these five patients had localized endocardial resection and/or cryoablative procedures when the ventricular tachycardia was well localized intraoperatively. In the remaining two patients, ventricular tachycardia was noninducible intraoperatively, and the patients underwent extensive endocardial resection and mitral valve replacement because of sites suspected near the posterior papillary muscle from preoperative catheter mapping. None of these five patients had inducible ventricular tachycardia postoperatively, and all are clinically free of the arrhythmia over a 24 month follow-up period. One patient with two morphologies of ventricular tachycardia previously had an unsuccessful blind endocardial resection. She underwent map-directed cryoablation of both sites of ventricular tachycardia. Postoperatively, the patient was free of inducible arrhythmia and has been asymptomatic over 8 months. Five patients had pleomorphic ventricular tachycardia or fibrillation that could not be electrically localized. One patient with ventricular fibrillation underwent extensive endocardial resection, but the posterior papillary muscle was spared. Postoperative electrophysiological study was positive. The patient has had no clinical ventricular arrhythmias on a regimen of amiodarone, however. Two patients had extensive endocardial resection and mitral valve replacement. One died early in the postoperative course and the other is clinically well. The remaining two patients had an encircling endocardial ventriculotomy. Both are clinically stable although one had inducible ventricular fibrillation postoperatively. We conclude that well-defined monomorphic ventricular tachycardia in patients with a previous inferior myocardial infarction can be successfully treated with localized endocardial resection and/or cryoablation. However, patients with poorly localized monomorphic ventricular tachycardia or pleomorphic ventricular tachycardia or fibrillation may require more extensive procedures. The role of posterior papillary muscle sacrifice with mitral valve replacement remains undefined.(ABSTRACT TRUNCATED AT 400 WORDS)

Transcatheter ablation: comparison between laser photoablation and electrode shock ablation in the dog

To characterize and compare the effects of transcatheter laser and electrical energy on endocardium, 35 laser pulses were delivered to the endocardial surfaces of isolated canine hearts, and 33 endocardial lesions were produced by the transarterial delivery of either transcatheter laser irradiation or electrical shock in closed-chest anesthetized dogs. Laser-induced lesion dimensions in vitro and in vivo increased with increased total dose of energy; however, the lesions produced in vivo were different in morphology and were significantly larger than lesions produced by equivalent doses of energy delivered in vitro (p less than .05). Endocardial lesions produced in vivo by laser at 40 and 80 J (7.9 X 5.4 X 6.6 and 7.9 X 5.1 X 7.5 mm) were comparable in gross morphology and size to those produced by electrical shock at 100 and 200 J (8.5 X 6.6 X 6.6 and 10.0 X 8.5 X 8.2 mm, respectively; p = NS), but transcatheter electrode shock produced significantly more ventricular tachycardia (p less than .003), premature ventricular beats in the 7 min after energy discharge (p less than .05), and wall motion abnormality (p less than .005). Transcatheter laser photoablation can create controlled endocardial lesions with less energy and fewer deleterious effects than transcatheter electrode shock.