Idiopathic ventricular tachycardia. An intracardiac electrical, hemodynamic and angiographic assessment of six patients

Asymmetry of cardiac [123I] meta-iodobenzyl-guanidine scans in patients with ventricular tachycardia and a "clinically normal" heart

OBJECTIVE

Patients with exercise induced ventricular tachycardia associated with a "clinically normal" heart may have an abnormality of the regional distribution of the cardiac sympathetic nerve supply. In this study the regional distribution of the myocardial nerve supply in patients with ventricular tachycardia (VT) and control subjects was examined by [123] meta-iodobenzylguanidine (MIBG) scanning.

PATIENTS AND DESIGN

Eight patients with exercise induced VT and seven patients with VT unrelated to exercise with "clinically normal" hearts were studied and compared with a control group of six subjects with atrioventricular reentrant tachycardia not related to exercise and eight patients with angiographically normal left ventricular function and normal coronary anatomy who had thallium scans without evidence of ischaemia or fixed perfusion deficits.

METHODS

Single photon emission computed tomography gamma scanning was performed in patients three hours after intravenous injection of MIBG. The left ventricular MIBG uptake data was processed into bull's-eye target plots. The inferior portion of the scan frequently showed artefact due to uptake of MIBG in the liver or spleen and was not used for statistical analysis. Asymmetry of uptake was defined as a ratio of uptake exceeding 1.25 in the upper quadrants (posterior (anterolateral free wall)/anterior (anteroseptal region)) of the MIBG scan.

RESULTS

Patients with VT had a higher proportion of asymmetrical MIBG scans (47%) than subjects in the control groups (0%) and this was particularly obvious in the patients with exercise induced VT (62.5%). This suggests that patients with VT may have relative denervation in the septal portion of the left ventricle leading to an imbalance of the sympathetic supply to the myocardium and locally imbalanced sympathetic or parasympathetic interactions. Considerable evidence from animal experiments suggests that imbalance of the sympathetic supply to the myocardium is important in the genesis of ventricular arrhythmia.

CONCLUSIONS

These results support the hypothesis that selective denervation of the human myocardium may be an important mechanism in the genesis of VT in "clinically normal" hearts.

Efficacy of flecainide, sotalol, and verapamil in the treatment of right ventricular tachycardia in patients without overt cardiac abnormality

OBJECTIVE

A comparison of the efficacy of verapamil, sotalol, and flecainide to suppress right ventricular tachycardia (VT) in patients with a clinically normal heart.

DESIGN

Patients underwent treatment serially with verapamil (360 mg daily), sotalol (240 or 320 mg daily), and flecainide (200 or 300 mg daily), (the larger dose was for patients heavier than 80 kg) to suppress tachycardia. Each drug was given orally for five half lives before testing.

PATIENTS

23 patients with right VT associated with a clinically normal heart were studied.

OUTCOME MEASURES

The effects of drug treatment were examined by the number of ventricular events on 24 hour Holter monitoring, and the ability of tachycardia to be induced by treadmill exercise testing (Bruce protocol) and programmed ventricular stimulation (Wellens protocol), compared with drug free baseline tests.

SETTING

Patients were studied in a tertiary referral centre.

RESULTS

All three drugs suppressed ventricular salvos (> 3, < 5 consecutive ventricular premature contractions) (p < 0.01) and VT (p < 0.05) on Holter monitoring and did not differ statistically in effect. Exercise induced VT was also suppressed by all three drugs (p < 0.01), and of these sotalol was the most effective although this was not statistically significant (14/23 inducible when drug free, 4/23 on flecainide, 2/23 on sotalol, 5/23 on verapamil). Sustained and non-sustained VT induced by programmed stimulation was also suppressed by the three drugs (p < 0.01) and again sotalol was the best of these though the differences did not achieve statistical significance (17/23 inducible when drug free, 4/17 on flecainide, 2/17 on sotalol, and 6/17 on verapamil). Proarrhythmic effects of drugs were found in a few patients. There was no difference in the efficacy of the drugs in patients with histological abnormalities of the myocardium when compared with those of normal histology.

CONCLUSIONS

Ventricular tachycardia associated with a clinically normal heart can be suppressed by flecainide, sotalol, or verapamil. In individual patients sotalol was the most frequently effective drug (effective in > 89% of patients) and is a suitable choice for first line treatment.

New-onset ventricular tachycardia during pregnancy

During evaluation for palpitations, presyncope, or syncope, seven pregnant women had documented ventricular tachycardia. Before pregnancy none had a history of significant cardiac disease or symptomatic arrhythmia. The tachycardia rate ranged from 117 to 250 beats/min and lasted up to 65 seconds. Arrhythmia evaluation in five of the patients suggested catecholamine-sensitive ventricular tachycardia. This diagnosis was supported by either a positive relation to exercise or isoproterenol infusion, suppression of arrhythmia by beta-blockade or sleep, and lack of induction of arrhythmia by programmed electrical stimulation of the heart. The arrhythmias resolved in one patient soon after evaluation and in one other patient after 2 months of controlling therapy. Five other patients continued to receive therapy throughout pregnancy. Delivery was accomplished in all patients without significant maternal or neonatal complications.

Conservative treatment of paroxysmal ventricular tachycardia during pregnancy

Paroxysmal ventricular tachycardia during pregnancy presents a therapeutic dilemma for the treating physician. The clinical course of two otherwise healthy pregnant patients with this arrhythmia in whom treatment was withheld is outlined. The indications and guidelines for treatment in relatively asymptomatic patients is discussed.

Nonischemic ventricular tachycardia. Clinical course and long-term follow-up in patients without clinically overt heart disease

This report describes the clinical, laboratory, and electrophysiologic features of 52 patients with ventricular tachycardia (VT) who had no clinical evidence of heart disease. The mean age of patients was 36 years, cardiovascular collapse occurred in 18 patients (35%), and exercise-related symptoms were present in 24 of 49 patients (49%). There were 20 patients with sustained monomorphic VT, 11 with incessant VT, and 21 with nonsustained VT. Abnormalities were present in 14 of 38 patients (37%) during echocardiography and in 21 of 47 patients (45%) who underwent cardiac catheterization. During baseline evaluation while patients were not receiving antiarrhythmic drugs, ambulatory monitoring and exercise testing showed an 88% and 57% incidence, respectively, of nonsustained or sustained monomorphic VT, whereas 31 of 50 patients (62%) had inducible VT (requiring an infusion of isoproterenol in 11 patients) during programmed electrical stimulation. The clinical VT (when a 12-lead electrocardiogram was available for analysis) had a left bundle branch block (LBBB) configuration in 20 of 33 patients (61%) and a right axis deviation in 17 of 33 patients (51%). The VT occurring during exercise testing and programmed electrical stimulation had the same configuration as the clinical VT in 22 of 22 patients. Three patients have received an antitachycardia pacemaker, and one patient underwent endocardial resection. Forty-eight patients (92%) were treated medically. One patient died of cancer; the remaining 47 patients were alive at a mean follow-up of 96 months after initial symptoms and 46 months after programmed electrical stimulation. We conclude that in patients without clinical evidence of heart disease, VT may be incessant, sustained, or nonsustained and that VT originates from the right ventricular outflow tract in more than 50% of patients. Although cardiac abnormalities may be found in more than 30% of patients, the exact significance of these abnormalities is unclear because of the absence of progressive changes and the excellent prognosis of this group of patients.

Determinants of the spontaneous ectopic activity in repetitive monomorphic idiopathic ventricular tachycardia

Twenty-four hour ambulatory electrocardiographic tape recordings of 30 patients (16 men and 14 women, mean age 42 +/- 17 years) with repetitive monomorphic idiopathic ventricular tachycardia were analyzed using a new computerized system designed to study 15 RR cycles and mean heart rate of the 3 minutes preceding any defined event. The mean (+/- SD) number of events analyzed per patient in 24 hours was 610 +/- 483 for single premature ventricular complexes, 622 +/- 490 for couplets, 260 +/- 411 for runs of 3 complexes, 186 +/- 476 for runs of 4, 108 +/- 173 for runs of 5, 82 +/- 129 for runs of 6 to 10 and 83 +/- 116 for runs of more than 10 complexes. The heart rate was faster before runs of ventricular tachycardia than before isolated extrasystoles (p less than 0.01) and a positive linear correlation was observed between the mean preceding heart rate and the type of extrasystolic activity, the length of the runs increasing with increasing preceding heart rate (r = 0.98, p less than 0.001). A long RR interval just before the occurrence of runs was present in 77% of the cases (23 of 30) with or without an oscillatory pattern of RR intervals due to bigeminy or trigeminy, and the length of the runs correlated positively with the duration of this long preceding diastole (r = 0.90, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Solitary beta-blocker therapy for idiopathic life-threatening ventricular tachyarrhythmias

To determine the clinical characteristics of patients with life-threatening ventricular tachyarrhythmias with no identifiable heart disease, we analyzed six patients who presented with either cardiac arrest or syncope associated with documented ventricular tachycardia or fibrillation. Electrocardiographic and echocardiographic examination and cardiac catheterization results were normal in all patients. Electrocardiographic monitoring revealed ventricular tachycardia in all patients. Exercise testing did not provoke sustained ventricular tachycardia in any patient. Programmed extrastimulation did not induce ventricular tachycardia in any patient. Isoproterenol infusion facilitated provocation of sustained ventricular tachycardia in only one patient. All six patients were treated with solitary beta-blocker therapy. Following treatment, there was a significant reduction in the incidence of ventricular tachycardia, couplets and total ventricular ectopic beats. During a follow-up period ranging from 16 to 36 (mean 22) months, all patients remain alive without clinically significant recurrence. Therefore, patients with life-threatening ventricular tachyarrhythmias without identifiable heart disease may respond to solitary beta-blocker therapy.

Cardiac histologic findings in patients with life-threatening ventricular arrhythmias of unknown origin

Percutaneous endomyocardial biopsy (right ventricle in 10, left ventricle in 2) was performed in 12 patients, aged 9 to 57 years, with serious ventricular arrhythmias occurring in the setting of normal cardiac anatomy and mechanical function. Light microscopic examination of tissue revealed histologic abnormalities in 11 patients, including myocardial cellular hypertrophy in 7, interstitial fibrosis in 5, endocardial fibrosis in 2, myocardial degenerative changes in 1 and increased interstitial cellularity in 1. One patient had histologic evidence of acute lymphocytic myocarditis. Thus, a majority of patients with serious ventricular arrhythmias and normal cardiac anatomy had histologic abnormalities, bringing into question the concept of primary electrical heart disease or idiopathic ventricular tachycardia.

Ventricular tachycardia of left bundle branch block configuration in patients with isolated right ventricular dilatation. Clinical and electrophysiological features

Electrophysiological studies showed ventricular tachycardia in five patients (four male, one female) with isolated right ventricular dilatation. All had been asymptomatic before the onset of palpitation which had developed in adolescence or early adult life. Tachycardia had been associated with syncope in four patients, and three had been resuscitated from ventricular fibrillation before investigation. The electrocardiogram during ventricular tachycardia showed a left bundle branch block pattern, and endocardial mapping at electrophysiological study confirmed the right ventricular origin. The presenting tachycardia could be induced in all patients by programmed stimulation, and in three patients ventricular tachycardia of differing configuration could be induced, but the right ventricular origin and left bundle branch block pattern were maintained. In two patients ventricular tachycardia degenerated into ventricular fibrillation. Cineangiography, cross sectional echocardiography, and multigated radionuclide angiography confirmed the dilated abnormal right ventricle while indicating that left ventricular function was normal. On resting electrocardiograms T wave inversion over the right precordial leads was the sole abnormality. There were no signs of right heart failure and exercise tolerance was normal. Four patients have received maintenance treatment with antiarrhythmic drugs, and one had undergone operative mapping and ablative surgery. Thus ventricular tachycardia complicating right ventricular dilatation may be associated with serious symptoms and ventricular electrical instability; and in adults it may be suspected on clinical grounds by inverted T waves in the right precordial leads.

Clinical characteristics and results of electrophysiologic testing in young adults with ventricular tachycardia or ventricular fibrillation

Thirty-one patients 16 to 40 years of age (mean +/- SD = 30.7 +/- 7 years) had one or more episodes of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Underlying cardiac abnormalities consisted most commonly of cardiomyopathy (nine), long QT syndrome (LQTS) (five), and mitral valve prolapse (five); no identifiable heart disease was found in four patients. Programmed ventricular stimulation induced VT in only one of four patients with the LQTS but induced VT in 64% of 22 patients with other abnormalities. Chronic drug treatment was based either on serial electropharmacologic testing or was empiric when electrophysiologic testing failed to provoke an arrhythmia. Using this approach, we found a 13% incidence of recurrent VT and a 10% mortality over a follow-up period of 18.1 +/- 13.9 months. In young adults with VT or VF, an underlying cardiac abnormality can usually be found. Extensive evaluation should be performed to uncover the underlying cardiac abnormality as this may influence chronic management.

Right ventricular tachycardia: clinical and electrophysiologic characteristics

This report describes the clinical and electrophysiologic characteristics of 30 patients without myocardial disease who had ventricular tachycardia with the morphologic characteristics of left bundle branch block and inferior axis. The tachycardias were nonsustained in 24 patients, sustained (greater than 30 sec) in six patients, and provocable by exercise in 14 of 23 patients undergoing a standard Bruce protocol. Ventricular tachycardia was induced during electrophysiologic study in 22 of 30 patients. Programmed stimulation induced tachycardia in 10 of 30 patients, most frequently by rapid atrial or ventricular pacing. Isoproterenol infusion facilitated tachycardia induction in 13 of 23 patients. Endocardial activation mapping, performed in 10 patients, confirmed that earliest ventricular activation during tachycardia occurred at the right ventricular outflow tract on the interventricular septum. These tachycardias were unique in their responsiveness to a wide variety of antiarrhythmic drugs, including type I drugs and propranolol. During a mean follow-up of 30 months, no patient has died or experienced cardiac arrest. Two patients appear to be in spontaneous remission, and no patient has developed additional signs of cardiac disease.

Clinical spectrum of ventricular tachycardia with left bundle branch morphology

Twenty-nine patients with apparent ventricular tachycardia (VT) of left bundle branch block (LBBB) morphology were evaluated. Tachycardia was associated with an organic basis in 24 of 29 patients: 7 had Mahaim fibers of the nodoventricular type, 7 had arrhythmogenic right ventricular dysplasia, 5 had coronary heart disease, 3 had biventricular cardiomyopathy, and 2 had associated congenital heart disease. In many patients the underlying cardiac disease was not readily apparent. In the patients with a Mahaim fiber, the electrocardiogram taken during sinus rhythm was frequently normal. A reentry tachycardia with anterograde conduction over the nodoventricular fiber could mimic VT as diagnosed by the usual criteria; nodoventricular fibers were, therefore, often unsuspected before electrophysiologic evaluation. In patients with arrhythmogenic right ventricular dysplasia, cineangiography demonstrated abnormalities of the right ventricle, but only minor or no abnormalities of the left ventricle. Clinical and electrocardiographic features were not distinctive. Of the 29 patients, 22 had serious symptoms accompanying the tachyarrhythmia or had required cardioversion. Patients were followed up for an average of 20 months: 4 patients died. Thus, VT exhibiting an LBBB morphology is not uncommon and is frequently associated with organic heart disease, serious symptoms, and significant mortality. Right ventricular angiography and electrophysiologic study may clarify the diagnosis in these patients.

Clinical and electrophysiologic findings in patients with repetitive monomorphic ventricular tachycardia and otherwise normal electrocardiogram

Natural history, structural substrate, electrocardiographic and electrophysiologic characteristics and therapy were evaluated in 18 patients who demonstrated repetitive ventricular tachycardia, defined as repeated episodes of ventricular tachycardia that had a uniform QRS configuration and normal sinus-conducted QRS complexes between the episodes of tachycardia. The patients were young (mean age 37 years) and frequently had a long history of arrhythmias before this evaluation; only two patients has a history of syncope and six were completely asymptomatic. Fourteen patients had no evidence of underlying structural heart disease, three had mitral valve prolapse and one had congestive cardiomyopathy. Episodes of ventricular tachycardia tended to occur in clusters over a 24 hour electrocardiographic recording period. Repetitive ventricular tachycardia was induced in two of nine patients by programmed electrical stimulation, and in seven patients incremental atrial and ventricular pacing suppressed spontaneous arrhythmia. In the one patient whose tachycardia was induced by incremental ventricular pacing there was an inverse relation between pacing cycle length and the interval from the last paced complex to the first complex of ventricular tachycardia, indicating there was overdrive suppression. At a follow-up time of 0.5 to 8 years no patient had died or had worsening of symptoms. Encainide completely eliminated episodes of ventricular tachycardia during acute treatment in five of six patients tested. Seven patients received no antiarrhythmic therapy and the arrhythmia appeared to have spontaneously resolved in four of these patients. Repetitive ventricular tachycardia appears to have distinct clinical and electrophysiologic characteristics. In this series the arrhythmia had a good prognosis and often required no treatment. The electrophysiologic features are consistent with a mechanism of automaticity.

Ventricular antiarrhythmic effects of beta-adrenergic blocking drugs: a review of mechanism and clinical studies

Beta-adrenergic blocking drugs are now commonly used in patients with ventricular arrhythmias. This review examines the possible mechanisms of their ventricular antiarrhythmic effect. Actions on the myocardial cell, as well as actions on the central and autonomic nervous system, are reviewed. Many clinical studies have attempted to show the efficacy of beta blockers in controlling ventricular arrhythmia and decreasing the incidence of sudden death after acute myocardial infarction. Although some of these clinical trials tended to show an impact on sudden death, the size of these trials or their design problems do not allow firm conclusions to be made. The Beta Blocker Heart Attack Trial (BHAT) is a placebo-controlled, double-blind, randomized trial of propranolol currently under way in the United States. Important additions to the previous trials include the addition of drug levels to ensure beta-blocking dosage, long-term electrocardiographic monitoring, and a study population of 4200 patients followed for an average of three years. These important design features will be of value in addressing some of the unanswered questions presented in this review.

Idiopathic recurrent sustained ventricular tachycardia in children and adolescents

The electrophysiologic characteristics of recurrent sustained ventricular tachycardia were studied in seven pediatric patients. The mechanisms of the ventricular tachycardia were evaluated using programmed electrical stimulation. Ventricular tachycardia could be reproducibly initiated in two patients and terminated in one patient in the basal state. It could be initiated in one additional patient and terminated in two additional patients after administration of a type IB drug. In four patients, ventricular tachycardia could not be initiated or terminated by programmed electrical stimulation. The site of origin of the ventricular tachycardia determined by catheter endocardial mapping was the right ventricular outflow tract in four patients, the interventricular septum in two patients and the inferior left ventricle in one patient. The ventricular tachycardia more frequently had an automatic than a reentrant mechanism, and originated more often in the right than in the left ventricle; it was not frequently associated with structural heart disease in this group of patients.

Exercise-induced ventricular tachycardia. Clinical features, relation to chronic ventricular ectopy, and prognosis

To determine the clinical status, the occurrence of chronic ambulatory arrhythmias, and the prognosis of patients with exercise-induced ventricular tachycardia, 26 patients with ventricular tachycardia during or immediately following exercise on a treadmill were evaluated. Of the 26 patients, 16 had coronary arterial disease, two had nonischemic cardiomyopathy, and eight had no other cardiac disease. Eleven (61 percent) of the 18 patients with heart disease developed ventricular tachycardia during exercise, in contrast to six (75 percent) of eight normal subjects who had ventricular tachycardia after exercise. In eight patients with repeat stress testing, four (50 percent) had reproducible ventricular tachycardia or malignant ventricular ectopic beats. In 19 (73 percent) of 29 patients, malignant ventricular ectopy occurred on random 24-hour electrocardiographic monitoring; ventricular tachycardia occurred in 5/26 (19 percent), and malignant ventricular ectopic beats occurred in 14/26 (54 percent). Fifteen (83 percent) of 18 patients with cardiac disease vs 4 (50 percent) of eight normal subjects (P less than 0.05) evidenced malignant ventricular ectopy during ambulatory monitoring. Only one episode of sudden cardiac death occurred in 24 patients followed for 21 months. Thus, 30 percent (eight) of the patients with exercise-induced ventricular tachycardia had no evidence of heart disease. Furthermore, exercise-provoked ventricular tachycardia presaged sudden death in only one of 24 patients; however, ventricular tachycardia with exercise correctly predicts the presence of chronic advanced ventricular ectopic beats or ventricular tachycardia in 73 percent (19/26) of the patients.

Preeminence of the left stellate ganglion in the long Q-T syndrome

In seven patients with Romano-Ward syndrome, stellate ganglion block or stimulation and pharmacologic interventions were made to assess their influence on duration of the O-T interval, electrical alteration of the T wave and ventricular tachydysrhythmias. Left stellate ganglion block and right stellate ganglion stimulation shortened Q-T interval, abolished alternans phenomena and suppressed tachydysrhythmias. Propranolol and phenytoin had a similar effect. In contrast, right stellate ganglion block, left stellate ganglion stimulation and prior administration of quinidine and procainamide had an opposite effect. These responses resemble observations in animal models which suggest that excessive or unopposed activity of the left, or subnormal activity of the right stellate ganglion, or both, account for the pathophysiologic manifestations of the long Q-T syndrome. They are also consistent with clinically correlated, cardiac neuropathologic findings in these patients. An analogous but acquired dysautonomia involving the left stellate ganglion and ischemic left ventricle may precipitate sudden coronary death.

Recurrent sustained ventricular tachycardia. 4. Pleomorphism

Two or more morphologically distinct ventricular tachycardias were observed during electrophysiologic study in 14 patients with chronic sustained ventricular tachycardia. Nine of these patients had clinical ventricular tachycardia with multiple morphologies. During the study 13 patients manifested both right bundle branch block (RBBB) and left bundle branch block (LBBB) morphologies. The remaining patient had RBBB with both right and left axis deviation. Changing morphologies were observed spontaneously in four patients and could be produced in all 14 by ventricular stimulation. In 12 patients both RBBB and LBBB originated in the left ventricle, and in 11 of these patients, from within a left ventricular aneurysm. Diastolic fragmented activity representing reentry was unchanged during both morphologies in four patients and during one morphology in five patients. Epicardial mapping confirmed the aneurysm as the site of origin of multiform ventricular tachycardias in two patients. Our data suggest that 1) ventricular tachycardia is frequently pleomorphic; 2) multiple morphologies usually represent variable exit sites and/or ventricular activation during the same tachycardia; and 3) there is a frequent association of pleomorphic ventricular tachycardia with left ventricle aneurysm.