Low energy countershock using an intravascular catheter in an acute cardiac care setting.

We examined the feasibility, effectiveness, and safety of using an intravascular catheter positioned in the right ventricular apex for countershock in a coronary care unit setting in 8 patients who had recurrent ventricular tachyarrhythmia. Countershock using 2.5 to 40 J stored energy (damped sinusoidal wave form) was attempted 115 times to terminate 100 episodes of ventricular tachyarrhythmia (ventricular tachycardia, 91; ventricular flutter, 3; ventricular fibrillation, 6). Eighty-six (87%) of 99 countershock attempts for ventricular tachycardia, 3 (60%) of 5 for ventricular flutter, and 4 (36%) of 11 for ventricular fibrillation were successful using this technique. The catheters remained in stable position for 1 to 16 days without dislodgment. A majority of the countershocks were delivered by the regular nursing staff in the coronary unit. We conclude that low energy countershock through an intravascular catheter system is feasible, safe, and effective in a coronary care unit setting. Such a system should be beneficial in the acute management of patients who have recurrent ventricular tachycardia or fibrillation. The catheter lead may also prove useful in managing ventricular tachyarrhythmias that occur during electrophysiologic studies.