An evaluation study on the quietness of the ATS valve.

BACKGROUND The closure sound of the ATS bileaflet mechanical valve is said to be quieter than that of the other mechanical valves. However, the reasons for this are still unknown. In this study, we investigated the reasons for the quietness of the ATS valve closure sound. PATIENTS AND METHODS The valve closure sound was evaluated in 70 patients and in another 70 patients in whom the SJM valve had been used for single valve replacement, based on frequency analysis of the closure sound, measurement of the opening angle of the valve, cardiac function, and patient interviews. RESULTS In the valve closure sound analysis, the mean peak frequency of the valve closure sound was 1.02 kHz for the ATS valve, and the mean pressure was 22.8+/-4.04 dB. The mean peak frequency of the closure sound of the SJM valve was1.02 kHz, with another intermittent peak at 3 to 9 kHz in the human audibility range. The mean sound pressure was 25.0+/-3.20 dB. The noise classification score was 2.07+/-1.95 points for the SJM valve, significantly higher as compared with that for the ATS valve which was 0.36+/-0.95 points. Multilateral examinations showed a significant difference in the mean opening angle between the ATS and the SJM valves: the angle was 76.6+/-4.67 degrees for the ATS valve and 82.3+/-2.05 degrees for the SJM valve. CONCLUSION In view of the lower sound pressure in the human audibility range and lower patient awareness of the valve closure sound, the ATS valve would appear to be a superior mechanical valve when compared to the SJM valve from the point of view of the quality of life of the patients. The significant difference in the opening angle in patients with the ATS valve between those who were aware of the valve closure sound and those who were not suggested a possible association between the opening angle and the patient awareness of the valve closure sound.