Endocardial pacing, cardioversion and defibrillation using a braided endocardial lead system.

The clinical efficacy and safety of a second-generation braided endocardial pacing, cardioversion and defibrillation lead system was evaluated in 25 patients with ventricular tachycardia (VT) or ventricular fibrillation (VF). The lead system consisted of two 8Fr active fixation endocardial leads each with pacing and defibrillation electrodes and a thoracic patch electrode. Monophasic and biphasic shocks were delivered using a triple-electrode configuration with a right ventricular common cathode and right atrial and thoracic patch anodes. VT and VF were electrically induced. Rapid VT (rate > or = 180 beats/min) and VF were initially terminated by 20 J (550 V) shocks and slow VT (rate < 180 beats/min) by 10 J (400 V) shocks. One hundred fourteen episodes (rapid VT/VF 73, slow VT 41) were treated with 128 shocks (monophasic 80, biphasic 48). Mean ventricular pacing threshold was 0.7 +/- 0.5 ms before and 0.9 +/- 0.5 ms after endocardial shock delivery (p > 0.2). Mean ventricular electrogram amplitude in sinus rhythm was 11.9 +/- 5.7 mV before and 11.4 +/- 5.1 mV after shock delivery (p > 0.2). Simultaneous monophasic endocardial shocks terminated 53% of VF episodes at < or = 20 J. Simultaneous biphasic shocks terminated 94% of all VF episodes at < or = 20 J (p < 0.03). Efficacy of > or = 10 J shocks for rapid VT/VF was greater for biphasic (92%) versus monophasic (74%) shocks (p < 0.05) at lower average shock energy (15 +/- 7 J vs 19 +/- 7 J, respectively, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)