Pacemaker-induced change in prosthetic valvular sounds.

Variable intensity and timing of valvular sounds were noted in two patients with permanent pacemakers and prosthetic valves. In the first patient, who had a mitral and a tricuspid prosthesis, valvular opening sounds became widely separated with a change from nodal to ventricular paced rhythm. In a second patient, who had a mitral prosthesis in sinus rhythm with first-degree atrioventricular block, a very quiet closing sound increased markedly in intensity with the onset of ventricular pacing. The mechanism for these changes is described using a technique which at brief intervals throughout the cardiac cycle permitted documentation of simultaneously recorded phonocardiogram, electrocardiogram, and pulse tracings with a visible image of the prosthesis. In the usual patient with a prosthetic valve auscultatory changes should arouse a suspicion of malfunction; however, in the relatively uncommon patient with a prosthesis and an artificial pacemaker, it should be recognized that auscultatory changes may well have a physiologic explanation.