Idiopathic recurrent ventricular fibrillation

Short-Coupled Idiopathic Ventricular Fibrillation: A Literature Review With Extended Follow-Up

Idiopathic ventricular fibrillation is responsible for approximately 10% of cases of aborted cardiac arrest. Recent studies have shown that short-coupled ventricular premature complexes are present at the onset of idiopathic ventricular fibrillation in 6.6%-17% of patients. The present review provided information on 86 patients with short-coupled malignant ventricular arrhythmias that were reported as case reports or small patient series during the last 70 years. In 75% of the 81 cases published during the last 40 years, extended information and follow-up (from 2.63 ± 4.5 to 10.67 ± 7.8 years; P < 0.001, between the original publication to the latest update) could be obtained from the authors. The review shows that short-coupled malignant ventricular arrhythmias occurred almost equally in males and females, at the mean age of 40 years. A tendency for later occurrence of the arrhythmia by 4 years was observed in females. A prior history of syncope was noted in 45.3% of the patients, whereas arrhythmic storm occurred in 42% at presentation. The most common mode of revelation of short-coupled malignant ventricular arrhythmias was syncope (53.5%), followed by aborted cardiac arrest (26.7%) and recurrent arrhythmic event after prior implantable-cardioverter defibrillator implantation for idiopathic ventricular fibrillation (17.4%). For the first time, short-coupled malignant arrhythmias exhibiting "not-so-short" coupling intervals (≥350 ms) were found in a significant proportion of patients (17.4%). During long-term follow-up, quinidine yielded a slightly higher success rate in arrhythmia control than ablation. Larger studies are necessary to assess the best strategy for the management of this potentially lethal arrhythmia.

Mapping and ablation of idiopathic ventricular fibrillation

BACKGROUND

Ventricular fibrillation is the main mechanism of sudden cardiac death. The feasibility of eliminating recurrent episodes by catheter ablation has not been reported.

METHODS AND RESULTS

Twenty-seven patients without known heart disease (13 men, 14 women, 41+/-14 years of age) were studied after being resuscitated from recurrent (10+/-12) episodes of primary idiopathic ventricular fibrillation; 23 had received a defibrillator. The first initiating beat of ventricular fibrillation had an identical electrocardiographic morphology and coupling interval (297+/-41 ms) to preceding isolated premature beats typically noted in the aftermath of resuscitation. These triggers were localized by mapping the earliest electrical activity and ablated by local radiofrequency delivery. Outcome was assessed by Holter and defibrillator memory interrogation. Premature beats were elicited from the Purkinje conducting system in 23 patients: from the left ventricular septum in 10, from the anterior right ventricle in 9, and from both in 4. The interval from the Purkinje potential to the following myocardial activation varied from 10 to 150 ms during premature beat but was 11+/-5 ms during sinus rhythm, indicating location at peripheral Purkinje arborization. The premature beats originated from the right ventricular outflow tract muscle in 4 patients. The accuracy of mapping was confirmed by acute elimination of premature beats during local radiofrequency delivery. During a follow-up of 24+/-28 months, 24 patients (89%) had no recurrence of ventricular fibrillation without drug.

CONCLUSIONS

Primary idiopathic ventricular fibrillation is a syndrome characterized by dominant triggers from the distal Purkinje system. These sources can be eliminated by focal energy delivery.

A new class of antiarrhythmic-defibrillatory agents

Novel dibenzoazepine and 11-oxo-dibenzodiazepine derivatives are shown to be effective ventricular defibrillating drug candidates. They exhibit significant in vivo defibrillatory activity with no observed changes in ECG either before or after the VF event. These compounds also exhibit antifibrillatory activity by elevating the fibrillation threshold potential, all suggesting that such drugs could be used to treat VF either by themselves or together with electrical defibrillators.

Polymorphic ventricular tachyarrhythmias in the absence of organic heart disease: classification, differential diagnosis, and implications for therapy

Different polymorphic ventricular tachyarrhythmias may cause syncope or cardiac arrest in patients with no heart disease: (1) Catecholamine-sensitive polymorphic ventricular tachycardia (VT) presents during childhood: the hallmark is the reproducible provocation of atrial and polymorphic ventricular arrhythmias during exercise, despite a normal QT. Beta-blockers are the treatment of choice. (2) In the long QT syndromes (LQTS), malfunction of ion channels leads to prolonged ventricular repolarization, early afterdepolarizations, and triggered ventricular arrhythmias. Therapeutic options include: beta-blockers, genotype-specific therapy, cardiac sympathetic denervation, and implantation of pacemakers or defibrillators. (3) The "short-coupled variant of torsade de pointes" is a malignant disease that shares several characteristics with idiopathic ventricular fibrillation. Although verapamil is frequently recommended, mortality rates remain high. (4) Idiopathic ventricular fibrillation (VF) with normal electrocardiogram (ECG) strikes young adults of both genders. In contrast to other polymorphic tachyarrhythmias, idiopathic VF is not generally related to stress. Also, familial involvement is rare. Therapeutic options include implantation of defibrillators and therapy with class 1A drugs. (5) The "Brugada syndrome" and the "syndrome of nocturnal sudden death" strike males almost exclusively. Right bundle branch block (RBBB) with ST elevation in the right precordial leads-the "Brugada sign"--is seen in the ECG of both patient populations. Implantation of defibrillators is recommended.

Mode of onset of malignant ventricular arrhythmias in idiopathic ventricular fibrillation

INTRODUCTION

The mode of onset of malignant ventricular arrhythmias (ventricular tachycardia [VT] or ventricular fibrillation [VF]) has been well described in patients with organic heart disease and in patients with the long QT syndromes. Less is known about the mode of onset of VF in patients with out-of-hospital VF who have no evidence of organic heart disease or identifiable etiology.

METHODS AND RESULTS

We reviewed the ECGs of all our patients with idiopathic VF. Documentation of the onset of spontaneous arrhythmias was available for 22 VF episodes in 9 patients (6 men and 3 women; age 41 +/- 16 years). In all instances, spontaneous VF followed a rapid polymorphic VT, which was initiated by premature ventricular complexes (PVCs) with very short coupling intervals. The PVC initiating VF had a coupling interval of 302 +/- 52 msec and a prematurity index of 0.4 +/- 0.07. These PVCs occurred within 40 msec of the peak of the preceding T wave. Pause-dependent arrhythmias were never observed.

CONCLUSION

Cardiac arrest among patients with idiopathic VF has a very distinctive mode of onset. Documentation of a polymorphic VT that is not pause dependent is of diagnostic value.

Idiopathic ventricular fibrillation in out-of-hospital cardiac arrest survivors

This study examined diagnostic and therapeutic roles of electrophysiological testing and long-term clinical outcome after out-of-hospital cardiac arrest due to idiopathic ventricular fibrillation. This is defined as ventricular fibrillation occurring in the absence of detectable underlying heart disease or metabolic or electrolyte disturbance. Out-of-hospital cardiac arrest resulting from idiopathic ventricular fibrillation is uncommon. Records of all patients who underwent electrophysiological testing between June 1979 and June 1992 were reviewed. Patients with out-of-hospital cardiac arrest due to idiopathic ventricular fibrillation were identified. Follow-up information was obtained by telephone interview in June 1992. Of 194 patients who underwent electrophysiological study after out-of-hospital cardiac arrest not associated with acute myocardial infarction, only six (4 male and 2 female) had idiopathic ventricular fibrillation. It was induced in only two patients by programmed ventricular stimulation. No sustained ventricular arrhythmias were induced in the remaining four patients. Four patients received implantable cardioverter defibrillators, one was treated with a beta-adrenergic blocker, and one received no treatment. All patients were alive at a mean follow-up of 50 months. Two of the four patients without inducible sustained ventricular arrhythmias had events during follow-up. Of the two patients with inducible ventricular fibrillation, one experienced a cardiac arrest and documented ventricular fibrillation at 41 months after the index event and the other had had no recurrence at 15-month follow-up. All four patients with implantable cardioverter defibrillators were alive at last follow-up, and two had device discharges.(ABSTRACT TRUNCATED AT 250 WORDS)

Short-coupled variant of torsade de pointes. A new electrocardiographic entity in the spectrum of idiopathic ventricular tachyarrhythmias

BACKGROUND

Torsade de pointes is characterized not only by its particular ECG pattern but by its context of congenital or acquired long QT syndrome and the long coupling interval of the initial premature beat.

METHODS AND RESULTS

We observed 14 patients aged 34.6 +/- 10 years (mean +/- SD) with no structural heart disease who presented with syncope related to a typical ECG aspect of torsade de pointes. However, there was no evidence of long QT syndrome, and the torsade had the unusual particularity of an extremely short coupling interval of the first beat or of the isolated premature beats (245 +/- 28 milliseconds). In 10 cases they deteriorated into ventricular fibrillation. Four patients had a familial history of sudden death. Only 2 patients had a tachyarrhythmia inducible by programmed stimulation. At Holter recordings the heart rate variability was globally and significantly depressed, the vagal limb of the autonomic nervous system being predominantly affected. During a mean follow-up of 7 years there were 5 deaths (4 sudden). Nine patients are alive, 3 with implanted defibrillators and 6 treated with verapamil alone. Unlike the other types of antiarrhythmic agents including beta-blockers and amiodarone, verapamil is in our experience the only drug apparently active on the arrhythmias; however, it does not prevent sudden death.

CONCLUSIONS

The short-coupled variant of torsade de pointes should be identified because of their ECG pattern and the risk of sudden death in young adults with no structural heart disease.

Idiopathic ventricular tachycardia and fibrillation

Important data have recently been added to our understanding of sustained ventricular tachyarrhythmias occurring in the absence of demonstrable heart disease. Idiopathic ventricular tachycardia (VT) is usually of monomorphic configuration and can be classified according to its site of origin as either right monomorphic (70% of all idiopathic VTs) or left monomorphic VT. Several physiopathological types of monomorphic VT can be presently individualized, according to their mode of presentation, their relationship to adrenergic stress, or their response to various drugs. The long-term prognosis is usually good. Idiopathic polymorphic VT is a much rarer type of arrhythmia with a less favorable prognosis. Idiopathic ventricular fibrillation may represent an underestimated cause of sudden cardiac death in ostensibly healty patients. A high incidence of inducibility of sustained polymorphic VT with programmed ventricular stimulation has been found by our group, but not by others. Long-term prognosis on Class IA antiarrhythmic medications that are highly effective at electrophysiologic study appears excellent.

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.

Torsades de pointes: arrhythmia, syndrome, or chimera? A perspective in the light of the Lambeth Conventions

What is torsades de pointes? Is it an arrhythmia or a syndrome? The distinction is critical. In this article I have attempted to explain why this is so. Both from the clinical and nonclinical standpoint, it is of overriding importance that torsades de pointes be amenable to measurement and quantification. This is the fundamental prerequisite for any variable to be of value as an endpoint in an investigation. Measurement and quantification require that a variable has an objective definition that is both inclusive and exclusive. In his seminal work, Dessertenne coined the term torsades de pointes to describe an arrhythmia with unusual features. However, torsades de pointes has been reinterpreted and redefined by Dessertenne's successors. It was originally described as occurring in certain settings (e.g., hypokalemia). However, this has been reinterpreted to mean that a specific set of antecedent conditions (such as hypokalemia) are part of the definition of torsades de pointes. If this is the case, then torsades de pointes is a syndrome, not an arrhythmia. For those more concerned with arrhythmias than with syndromes, the key issue to be determined is what to call the arrhythmia that is part of the syndrome. I have put forward some suggestions with the objective of answering this question, using the Lambeth Conventions as a guide. I believe that there is strong case for ventricular tachyarrhythmias to be classified simply as tachycardia or fibrillation, with the optional use of the term delayed repolarization syndrome in cases where a long QT interval is present. The latter term should be used as one might use the term acute myocardial ischemia, i.e., to denote an underlying condition; it should not be used to define the arrhythmia itself. Twenty-four years after its introduction, the term torsades de pointes has now become a chimera and is best abandoned.

Idiopathic ventricular fibrillation

A review of the literature dealing with sudden death revealed 19 articles in which ostensibly healthy patients with documented VF unrelated to any known cardiac or noncardiac etiology are reported. Fifty-four patients fulfilling the criteria for idiopathic VF, including 14 patients investigated at our institution, are described. The mean age of patients for studies that reported age data was 36 years, with a male-to-female ratio of 2.5 to 1. Over 90% of the patients required resuscitation, while syncope due to nonsustained VF occurred in the rest. Diagnosis of VF was preceded by syncope in one fourth of the patients. Holter monitoring and exercise stress tests were often unrewarding. Available electrophysiologic data revealed a 69% inducibility rate of sustained ventricular tachyarrhythmias using nonaggressive protocols of ventricular stimulation in most cases. Induced tachyarrhythmias were poorly tolerated, and were mostly of polymorphic configuration. Class IA antiarrhythmic agents were highly effective in preventing reinduction of these arrhythmias. Available figures suggest an 11% rate of sudden death within 1 year of diagnosis. Appropriate antiarrhythmic therapy appears to improve prognosis. Reviewed data suggest that idiopathic VF represents an underestimated cause of sudden cardiac death in ostensibly healthy patients. An international registry of patients with idiopathic VF is warranted.

Ventricular fibrillation in six adults without overt heart disease

Findings are described in six patients with no clinical evidence of heart disease who had documented ventricular fibrillation (five patients) or ventricular flutter (one patient). The mean age of the six patients, all men, was 34 years (range 26 to 43). Cardiovascular collapse occurred in all and was followed by successful cardioversion. No patient had electrolyte or QT abnormalities. One patient had slight right ventricular enlargement on M-mode echocardiography, and another had a left ventricular pressure gradient at rest of 30 mm Hg with a normal two-dimensional echocardiogram. Holter electrocardiographic monitoring revealed incessant ventricular tachycardia in one patient and nonsustained ventricular tachycardia in three others. Exercise testing revealed nonsustained ventricular tachycardia in one patient. Ventricular fibrillation was induced at the time of programmed electrical stimulation in four of the six patients. Documented recurrence of ventricular fibrillation or ventricular flutter occurred in three patients, but in only one patient receiving antiarrhythmic drugs. Four patients were treated with amiodarone and one received an automatic implantable cardioverter-defibrillator. All patients are alive after a mean follow-up period of 78 months after the first documentation of their arrhythmia and 37 months after programmed electrical stimulation. Ventricular fibrillation can occur in the apparently structurally normal human heart. Antiarrhythmic treatment can provide effective control of this malignant arrhythmia.

A polymorphic form of familial arrhythmogenic right ventricular dysplasia

Thirty-two members of a family were studied. Three of them died in their youth and had evidence of arrhythmogenic right ventricular (RV) dysplasia. The other 29 members underwent clinical examination, electrocardiography, chest x-ray and M-mode and 2-dimensional echocardiography. Fourteen patients found to have structural abnormalities of the right ventricle underwent 24-hour ambulatory electrocardiographic recording and symptom-limited bicycle stress testing. Hemodynamic and angiographic studies were performed in 6 of these patients. In this family the arrhythmogenic RV dysplasia showed a wide variation of abnormalities, ranging from mild, local alterations to generalized involvement of the right ventricle. The patients were separated into 3 groups on the basis of both the clinical profile and noninvasive/invasive studies: 3 subjects who died suddenly; 3 subjects who had severe ventricular arrhythmias; and 8 subjects in whom RV impairment was not associated with any significant arrhythmias. There was no close relation between the severity of the RV abnormality and presence of ventricular arrhythmias. The variability of the RV abnormality and the high prevalence of this condition in this family is consistent with a genetic pattern of autosomal dominance with incomplete penetrance.

Idiopathic ventricular fibrillation: inducibility and beneficial effects of class I antiarrhythmic agents

Ventricular fibrillation in patients without recognizable heart disease is uncommon and electrophysiologic data on such patients is limited. Over a 7 year period, five patients (three men and two women, ranging in age from 24 to 52 years) without demonstrable heart disease underwent electrophysiologic studies with pharmacologic drug testing because of single (four patients) or multiple (one patient) documented episodes of ventricular fibrillation. The arrhythmic event was unrelated to myocardial ischemia or infarction, metabolic or electrolyte disturbances, drug toxicity, preexcitation, or prolonged QT syndromes. In all three patients receiving no antiarrhythmic drugs and in two pretreated with amiodarone, a rapid poorly tolerated ventricular tachyarrhythmia requiring cardioversion was induced by programmed ventricular stimulation with up to two extrastimuli. In all instances, addition of either oral quinidine or oral disopyramide prevented the induction of sustained ventricular arrhythmias. All five patients were placed on antiarrhythmic drug regimens found effective during electrophysiologic studies and remained asymptomatic during follow-up periods ranging from 12 to 93 (mean 52) months. We conclude that in the patients with idiopathic ventricular fibrillation in our study: programmed ventricular stimulation reliably replicated the spontaneous arrhythmia, class I antiarrhythmic agents effectively prevented induction of the arrhythmia in the laboratory, and in contrast to the severity of the presenting arrhythmia, a benign clinical course was observed during long-term therapy with class I antiarrhythmic agents.

Beta blocker therapy in 125 cases of hypertension during pregnancy

Over a period of 4 years, a team of obstetricians and nephrologists have used beta-blockers in the treatment of hypertension in high risk pregnancies. One hundred and twenty one patients (125 pregnancies) were treated with this new therapeutic approach: Acebutolol (56 cases), Pindolol (38 cases) and Atenolol (31 cases) were used. In our group of patients, 56% (70/121) had a previous record of hypertension. Treatment was started when diastolic pressure reached 90 mmHg. The mothers showed excellent tolerance and in 95% of cases blood pressure was controlled in a satisfactory manner. Three groups of new-born infants were defined. In 20 infants, the weight was less than 2.5, in 15 infants between 2.5 and 2.8 kg, and in 90 infants more than 2.8 kg. There was no evidence of low Apgar scores, bradycardia or hypotension in the infants. The importance of team management of the patient is emphasised.

The possible adverse effect of propranolol on the fetus in pregnancies complicated by severe hypertension

A retrospective study is presented of the effect of propranolol on fetal outcome in pregnancies complicated by maternal hypertension. In nine pregnancies in which propranolol was given to markedly hypertensive women (diastolic blood pressure over 105 mm Hg) the fetal outcome was worse than in 15 patients using other hypotensive agents. The probability of fetal or neonatal death was related to the amount of proteinuria and the presence of parenchymal renal disease but was also significantly higher when the mother had been treated with propranolol. Experimental evidence suggests that beta-adrenergic blockade is harmful to the hypoxic fetus, for these reasons the use of propranolol in hypertensive pregnancies complicated by placental insufficiency may be contraindicated unless there is no satisfactory alternative.