Sudden death after catheter-induced atrioventricular junctional ablation.

Atrioventricular (AV) junctional ablation was performed in a 59-year-old woman with recurrent atrial fibrillation refractory to treatment with digoxin, beta-blockers, verapamil, quinidine, procainamide, and amiodarone. She received two shocks of 500 J which produced complete AV block. After six weeks, both 24-hour ECG recordings and an exercise tolerance test showed infrequent premature ventricular complexes, 3 degrees AV block, and paced ventricular rhythm with 100 percent capture. She suddenly collapsed and was found to be in ventricular fibrillation and could not be resuscitated. Serial sections of the conduction system showed marked fatty infiltration of the approaches to the AV node with almost complete separation from the node. A partially fibrosed atrioHisian connection was also present. Fibroelastosis with chronic inflammatory changes was present in the AV node, bundle of His, and right and left bundle branches. In addition, marked inflammatory changes with fibrosis were present in the atrial septum, in the summit of the ventricular septum, with degenerative changes in the tricuspid and aortic valves. The sequelae of these findings outside the conduction system in other patients remains to be determined.