A 35-year-old man had a history of recurrent syncope for more than a decade. During a witnessed episode, an ambulatory electrocardiographic recording showed ventricular flutter/fibrillation that lasted for 2 1/2 minutes and terminated spontaneously without adverse neurologic sequelae. No structural heart disease and no possible etiologic factor for the ventricular tachyarrhythmia was found. The patient received an automatic implantable cardioverter defibrillator. Review of the literature suggests that the automatic implantable cardioverter defibrillator is a valid option in idiopathic ventricular fibrillation in young individuals to avoid the potential risk of recurrent cardiac arrest.
(Chest 1994; 106:1601-03)
VF=ventricular fibrillation
Key words: automatic implantable cardioverter defibrillator; idiopathic ventricular fibrillation; programmed electrical stimulation; syncope
Syncopal episodes in young individuals without heart disease are rarely due to ventricular fibrillation (VF). Ambulatory monitoring in these cases is rarely helpful due to infrequency of the attacks. We report herein a case of recurrent syncope for over 10 years due to idiopathic ventricular flutter-fibrillation first documented by Holter monitoring, lasting 2 min and 30 s, and resolving spontaneously.
CASE REPORT
A 35-year-old black man was referred to the Brooklyn Veterans Administration Medical Center for syncopal attacks after repeated unrewarding neurologic workup that included multiple electroencephalograms and two head computed tomographic (CT) scans.
For 10 years the patient was treated with phenytoin (Dilantin) in therapeutic dosage that he took regularly except during the period between 1983 to 1986 while serving in the Army in his effort to avoid medical restrictions. The syncopal episodes were often preceded by numbness of legs, diaphoresis, dizziness, and shortness of breath and were always associated with palpitations. The episodes were not related to change in posture, exertion, or meal intake. Tonicoclonic movements were frequently reported by sporadic witnesses. The frequency of attacks varied from 3 to 20 per year except for an asymptomatic period while in the military service. However, several attacks occurred while the patient was not taking phenytoin. There was no history of alcoholic intake, smoking, or illicit drugs.
Results of physical examination and laboratory tests, including magnesium level, phenytoin level, and electrocardiogram, were within normal limits. A witnessed syncopal episode occurred at home while having a 24-h Holter recording. The recording revealed 16 episodes of very fast (up to 420 beats/min) polymorphic ventricular flutter/fibrillation with the longest episode lasting for 2 1/2 minutes before terminating spontaneously (Fig 1). Four of the 16 episodes followed a short-long-short cardiac cycle due to a preceding ventricular premature beat followed by a compensatory pause (Fig 2).
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The patient was admitted to the Coronary Care Unit on the same day. The electrocardiogram and the QTc interval were within normal limits. The two-dimensional echocardiogram and Doppler studies were normal except for minimal interventricular septal hypertorphy (1.3 cm) with similar findings by follow-up transesophageal echocardiogram. Myocardial infarction was excluded at the time of hospital admission. The signal-averaged ECG did not reveal any late potentials. Cardiac catheterization revealed normal pressures, normal coronaries, and normal right and left ventriculograms. The ejection fraction was 73 percent and there was no abnormal gradient across the valves or left ventricular outflow tract. Tilt table did not reveal any abnormality. Electrophysiologic studies conducted while not receiving phenytoin showed a normal sinus and atrioventricular nodal function, normal effective refractory periods at the apex, and outflow tract of the right ventricle. There was no evidence of accessory pathways. A polymorphic ventricular tachycardia at a rate of 360 beats/min was induced by stimulation of the right ventricular outflow tract with three extrastimuli [S.sub.1]/[S.sub.2]/[S.sub.3]/[S.sub.4]=400/190/190/180 ms). The tachycardia terminated spontaneously after 10 s and was associated with near syncopal attack. A monophasic action potential recording from different right ventricular sites did not reveal any abnormality. Follow-up CT scan of the heart did not show any abnormal findings, including pericardial fat distribution in support of right ventricular dysplasia.
The patient was referred for implantation of an automatic implantable cardioverter defibrillator. During surgery, neither morphologic abnormalities nor abnormal fat distribution was noticed. The patient had been followed-up for 24 months after surgery and no discharge has occurred so far.
DISCUSSION
Syncope is a symptom caused by a wide variety of diseases ranging from physiologic derangements with few consequences to diseases that may be life-threatening. Causes of syncope include neurocardiogenic syncope, orthostatic hypotension, drug-induced syncope, cerebrovascular diseases, hypersensitive carotid sinus, and cardiac diseases.(1) The latter could be classified into mechanical or arrythmogenic causes. Cardiac mechanical causes of syncope include the following: obstruction to left ventricular flow like aortic stenosis; hypertrophic cardiomyopathy, and mitral stenosis; obstruction to pulmonary flow like pulmonic stenosis, tetralogy of Fallot, pulmonary hypertension, and pulmonary embolism; pump failure as secondary to myocardial infarction; and cardiac tamponade. Arrhythmogenic causes of syncope include both bradyarrhythmias like sick sinus syndrome and atrioventricular block and tachyarrhythmias like supraventricular or ventricular tachycardia. Cardiac causes of syncope have been identified in 8 percent to 39 percent of patients in various studies.(1) Most studies have shown that in a large proportion of patients with syncope (38 percent to 47 percent), a cause is not established after standard diagnostic evaluation.(1)
The most interesting aspect of the present case is the recurrent spontaneous conversion of sustained VF. Although this has been reported in six other cases in the literature, to our knowledge, such prolonged and frequent episodes without neurologic sequelae are unique. There are few reports of VF in the presence of minimal or structural heart diseases.(2)(3)(4)(5) In a review of 54 cases of idiopathic VF, 50 patients required resuscitation while 4 had nonsustained VF with syncope.(2) Ventricular fibrillation was initiated by a ventricular premature beat with a very short coupling interval in many of the patients, including the present patient. Induction of polymorphic ventricular tachycardia and VF has been considered a nonspecific response to programmed stimulation and its incidence varied from 39 percent(5) to 69 percent(2) in two large study groups. Sustained monomorphic ventricular tachycardia is rarely induced.(4) Thus, programmed stimulation may not be useful in guiding therapy in survivors of idiopathic VF.
There is no recommended strategy for the management of idiopathic VF at present. Pharmacologic therapy has been tried often. Failure of amiodarone as a single-drug therapy was seen in three of four cases reviewed by Viskin and Belhassen(2) who found class IA to be associated with better prognosis in the short term. However, the value of pharmacologic therapy in idiopathic VF has yet to be established. In a recent report, a ten-center retrospective study provided information on 28 survivors of VF with minimal or no structural abnormalities who were treated with an implantable cardioverter-defibrillator.(5) The 3-year survival rate with the device was excellent and superior to that reported in survivors of cardiac arrest with structural heart disease similarly treated. Only a small number of patients (4 of 28) received shocks considered to be appropriate. However, the implanted device had no arrhythmia disclosure capability to be able to provide an accurate estimate of the incidence of appropriate shocks. The report suggests that an implantable cardioverter-defibrillator is a valid option in patients with idiopathic VF to avoid the potential risk of recurrent cardiac arrest. However, to our knowledge, there are no good data as yet to support its superiority to other modes of treatment.
REFERENCES
(1)Kapoor WN. Diagnostic evaluation of syncope. Am J Med 1991; 90:91-106
(2)Viskin S, Belhassen B. Idiopathic ventricular fibrillation. Am Heart J 1990; 120:661-67
(3)Lemery R, Brugada P, Della Bella P, Dugemier T, Wellens HJJ. Ventricular fibrillation in six adults without overt heart disease. J Am Coll Cardiol 1989; 13:911-16
(4)Belhassen B, Shapira I, Shoshani D, Paredes A, Miller H, Laniado S. Idiopathic ventricular fibrillation: inducibility and beneficial effects of class I antiarrhythmic agents. Circulation 1987; 75:809-16
(5)Meissner MD, Lehmann MH, Steinman RT, Mosteller ED, Akhtar M, Calkins H, et al. Ventricular fibrillation in patients without significant structural heart diseases: a multicenter experience with implantable cardioverter-defibrillator therapy. J Am Coll Cardiol 1993; 21:1406-12
COPYRIGHT 1994 American College of Chest Physicians
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