[Case of chronic trifascicular block resulting in cardiac arrest during operation].

An 82-year-old man underwent thoracoscopic upper lobectomy of the left lung for the treatment of the lung cancer. The major complication was asymptomatic chronic trifascicular block. During the surgery, after the upper lobe had been resected, second degree atrioventricular block (Morbitz type II) occurred unexpectedly, soon evolving in complete AV block, with pulse wave disappearing, indicating pulseless electrical activity. Immediately, we used an epicardial pacing wire, and spontaneous circulation returned. Postoperatively, a permanent pacemaker was implanted. Asymptomatic chronic bifascicular block and trifascicular block rarely progress into complete AV block during operation, which we should be prepared in advance. Accordingly in some cases, preoperative insertion of a temporary pacemaker should be considered as a preventive measure.