A tactic of last resort.

One of the lessons learned in the early days of open-heart surgery was how easily a surgeon could inadvertently create a complete atrioventricular block by damaging the bundle of His. Painstaking precautions have since been designed in order to identify the site of the bundle and thus protect it. At the same time, progress in pacemaker technology has made it possible to correct the consequences of an accidental lesion of the bundle. A particularly effective device has been the recently developed sequential atrioventricular pacemaker, which (as the name implies) makes use of the impulse triggered by the P wave, for . . .