An in vitro study of prosthetic heart valve sound.

Patients with an implanted mechanical heart valve sometimes experience the closing sounds of the valve as disturbing. To study the generation of valve sounds in general, a pulse duplicator study was carried out, testing eight commonly used types of prosthetic valves in the aortic position. Pulse rate was set at 70 beats/min, stroke volume at 70 ml and mean 'aortic' pressure at 100 mmHg. Despite the controlled conditions, there was great variability of the closing sound, in both intensity and spectral composition, making noise comparisons and spectral characterization ('sonoprint') difficult. In general, bileaflet mechanical valves produced less noise than did tilting disc valves, particularly those with large opening angles. One small-size (23 mm) tilting disc valve produced 50% less noise than large types. The plastic ball valve, the porcine and the polyurethane trileaflet valve all were very quiet.