Emergency intracardiac defibrillation for refractory ventricular fibrillation during routine electrophysiologic study

Ventricular fibrillation refractory to cardiopulmonary resuscitation including multiple transthoracic defibrillations occurred in four patients during 1,215 consecutive ventricular tachycardia induction studies. A technique of emergency intracardiac defibrillation for management of refractory ventricular fibrillation is described. In four patients, stable monomorphic ventricular tachycardia (320 to 570 ms cycle length) was induced during the study and overdrive ventricular pacing resulted in ventricular fibrillation. These patients did not respond to prompt transthoracic defibrillations (5 to 15 attempts/patient) and cardiopulmonary resuscitation, including antiarrhythmic therapy. As a last resort, intracardiac defibrillation was performed with use of a previously inserted standard right ventricular quadripolar catheter as cathode and a posterior skin patch as anode. High energy intracardiac defibrillation pulses (100 to 500 J) delivered from a standard defibrillator successfully terminated each arrhythmia. Intracardiac defibrillation is technically simple and appears effective in terminating refractory ventricular fibrillation in the electrophysiology laboratory. However, further research is necessary to determine the safety and efficacy of this technique, as well as potential applications in other emergency settings.