BUNDLE-BRANCH REENTRY - A MECHANISM OF VENTRICULAR-TACHYCARDIA IN THEABSENCE OF MYOCARDIAL OR VALVULAR DYSFUNCTION

Objectives. The aim of this study was to present bundle branch reentry as the mechanism of sustained ventricular tachycardia in the absence of myocardial or valvular dysfunction. Background. Previous reports ha ve documented the relation between structural heart disease and bundle branch reentrant ventricular tachycardia. Myocardial or valvular dysf unction has thus far been recognized as the only anatomic substrate fo r the development of this tachycardia. Methods. Three patients with a wide QRS complex tachycardia underwent noninvasive and invasive cardia c evaluation and electrophysiologic studies to identify the substrate and mechanism of tachycardia. Catheter ablation of the right bundle br anch using radiofrequency current was performed in each patient. Resul ts. The patients were all men (aged 54, 34 and 72 years) who presented with presyncope, palpitation and cardiac arrest, respectively. Electr ocardiography during sinus rhythm revealed nonspecific intraventricula r conduction delay in all three patients. Cardiac evaluation revealed no evidence of myocardial or valvular dysfunction in any patient. The baseline HV interval was prolonged in each patient (90, 100 and 75 ms, respectively). Programmed right ventricular stimulation initiated bun dle branch reentrant tachycardia with typical left (three patients) an d right (one patient) bundle branch block pattern. Catheter ablation o f the right bundle branch using radiofrequency current abolished bundl e branch reentry in all three patients. After 26-, 13 and 8-month foll ow-up periods, complete right bundle branch block persisted, and all t hree patients remained asymptomatic without antiarrhythmic drugs. Conc lusions. Sustained bundle branch reentry can be a clinical arrhythmia in patients with no identifiable myocardial or valvular dysfunction ex cept for isolated conduction abnormalities in the His-Purkinje system. This mechanism of tachycardia should be recognized during electrophys iologic evaluation, given the seriousness of this arrhythmia and the a vailability of effective treatment.