EMERGENCY INTRACARDIAC DEFIBRILLATION FOR REFRACTORY VENTRICULAR-FIBRILLATION

Hemodynamically unstable ventricular arrhythmias induced during electr ophysiologic testing almost always respond to prompt application of di rect current transthoracic shocks. In rare cases, however, ventricular fibrillation may be refractory to conventional treatment. Recently, a technique of intracardiac defibrillation has been successfully used t o resuscitate patients with ventricular fibrillation refractory to tra nsthoracic defibrillation. We describe two patients with a history of myocardial infarction and left ventricular dysfunction who were admitt ed with symptomatic episodes of ventricular tachycardia. Both had indu cible sustained monomorphic ventricular tachycardia. During a repeat e lectrophysiologic study in Patient No. 1 on procainamide and at the in itial study in Patient No. 2, right ventricular burst pacing to termin ate ventricular tachycardia resulted in ventricular fibrillation refra ctory to resuscitation efforts, including transthoracic defibrillation with 360 J. Emergency intracardiac defibrillation with 200 and 360 J, respectively, successfully converted both patients to sinus rhythm. B oth patients were subsequently discharged from the hospital on amiodar one. These cases illustrate the life-saving capabilities of intracardi ac defibrillation.