[Closed intracardiac cardioversion in therapy resistant atrial flutter].

Cardiac frequency could not be lowered in a 62-year-old patient with atrial flutter and 2:1 conduction. Using an electrode catheter positioned in the His bundle area an electric current of 80 Ws was effected. A third-degree atrioventricular block developed which regressed after 6 hours. The electrophysiologic assessment after one week showed a marked diminution of AV node conduction capacity.