Are sounds from mechanical heart valves equal for different valve types?

BACKGROUND AND AIM OF THE STUDY: The closing 'click' sounds from mechanical heart valve prostheses are often clearly audible for patients and their relatives. These sounds have been recognized as a disturbing factor causing sleeping disturbances or social embarrassment, which patients must endure for the rest of their lives. The study aim was to determine whether the intensity of the transmitted sounds varies according to the type of valve implanted.

METHODS

Closing sounds were measured from 15 patients with ATS valves, 29 with Medtronic-Hall valves, and 40 with St. Jude Medical (SJM) valve prostheses; all prostheses were implanted in the aortic position. The sounds were recorded by a microphone placed 5 cm above the chest of the patient when placed in a supine position in a bioacoustical laboratory. The mean sound pressure levels (SPLs) from the valves were measured in dB(A).

RESULTS

The mean SPL values were 43 +/- 5 dB(A) for ATS valves, 41 +/- 4 dB(A) for Medtronic-Hall valves and 40 +/- 4 dB(A) for SJM valves (p < 0.05, ATS versus SJM).

CONCLUSION

The study results showed a statistically significant difference in SPLs among the three investigated mechanical heart valve prostheses. The highest levels were in the ATS valves, and the lowest in the SJM valves. These objectively measured SPLs must be correlated with the sound as perceived by the patient in order to determine the annoyance that they cause.