RECURRENT VENTRICULAR TACHYCARDIA - ELECTROPHYSIOLOGIC APPROACH

Recurrent sustained ventricular tachycardia frequently occurs in the setting of clinically significant cardiac disease, particularly ischemic heart disease. It is a major complication of chronic ischemic heart disease, especially that associated with chronic myocardial infarction complicated by ventricular aneurysm. It may also be found in a wide variety of disorders including electrolyte imbalance, drug toxicity, prolonged QT interval syndromes, mitral valve prolapse, and on occasion in otherwise normal individuals. The clinical significance of this arrhythmia derives from (1) the electrical instability which may result in deterioration to ventricular fibrillation, (2) the hemodynamic disadvantages of the arrhythmia which result from deceased diastolic filling due to the rapid rate, loss of atrial 'kick' due to atrioventricular dissociation, abnormal sequence of ventricular depolarization resulting in a less efficient contraction, and functional mitral regurgitation, and (3) the potential of increasing myocardial ischemia with further deterioration in both electrical stability and hemodynamic status. The therapy of this arrhythmia is often very difficult and the availability therapeutic modalities are associated with a high incidence of intolerable side-effects and, on occassion, death. The purpose of this review is to present an organized electrophysiologic approach to the diagnosis and treatment of this arrhythmia so that a more rational therapeutic approach can be applied. The goals of the electrophysiologic evaluation of ventricular tachycardia include (1) confirming the diagnosis of ventricular tachycardia, (2) defining the mechanism, (3) evaluating the efficacy of pharmacologic and/or electrical therapy, and (4) localizing the site of origin as a guide to the surgical ablation of the arrhythmia.