Ultrasonic Closing Click of the Prosthetic Cardiac Valve

Jun HASEGAWA  Kenji KOBAYASHI  Hiroshi MATSUMOTO  

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E81-D   No.12   pp.1517-1521
Publication Date: 1998/12/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8532
Type of Manuscript: LETTER
Category: Bio-Cybernetics and Neurocomputing
Keyword: 
prosthetic cardiac valve,  closing click,  ultrasonic click,  audible click,  

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Summary: 
Mechanical prosthetic cardiac valves generate not only the widely recognized audible closing clicks but also ultrasonic closing clicks, as previously reported by us. A personal-computer-based measurement and analysis system with the bandwidth of 625 kHz has been developed to clarify the characteristics of these ultrasonic closing clicks. Fifty cases in total were assessed clinically, including cases with tilting disk valves, bileaflet valves, and flat disk valves. The ultrasonic closing clicks are damped vibrations continuing for about two milliseconds, and their frequency range was confirmed to be from 8 kHz to 625 kHz, while that of the audible click was up to 8 kHz. Although the sensitivity of the sensor decreased by approximately 30 dB at 625 kHz, effective power of the ultrasonic closing click was confirmed at this frequency. Moreover, it was shown that, surprisingly, the signal power at 625 kHz was still at the same level as that at around 100 kHz. Those wide bandwidth signal components exist independent of the type of mechanical valve, but the spectral pattern shows some dependence on the valve type.