[Intracardial shock for the conversion of chronic atrial fibrillation].

Internal cardioversion was attempted in three patients with chronic atrial fibrillation, refractory to conventional external direct current shocks. Endocardiac shocks were delivered between the proximal electrode on a multipolar USCI pacing catheter and a back paddle. This is positioned with the tip proximal of the bundle of His, and the proximal ring electrode floating in the right atrium. Two patients were converted with 200 Joules, one needed 400 Joules. Two of our three patients were chronically maintained in sinus rhythm after the initial conversion, one had recurrence within 24 hours.