Transvenous Pacing, Alternate Bilateral Bundle-Branch Block, and Syncope

The development of permanent transvenous pacing techniques has simplified the treatment of bradycardiac syndromes. Though relatively free of complications, permanent implanted transvenous pacing systems may present a variety of problems after implantation. Complications include perforation of the ventricular myocardium, interventricular septal perforation, dislodgment of the electrode catheter, changing myocardial thresholds, and generator failure. More recently it has been recognized that the pacing catheter may be accidentally positioned in the coronary sinus or its tributaries or both. We recently treated a patient who had recurrent syncope, and alternating right and left bundle-branch block following implantation of a permanent transvenous demand pacemaker. Further study indicated that the pacing catheter had been positioned via the coronary sinus into the posterior coronary vein. Patient Summary A 60-year-old man was admitted to Duke University Medical Center on May 20, 1971, because of repeated episodes of syncope and mental deterioration. A transvenous demand-type pacemaker had been