The frequency analysis of prosthetic valve sounds using digital transmission for remote diagnosis to detect the malfunction

概要

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To detect malfunction in prosthetic heart valves at an early stage, we have effectively analyzed prosthetic valve sounds (PVS) using trans-telephone PCG monitoring. To analyze more precisely, we attempted frequency analysis of PVS by digital transmission. [Method] We developed a new telephone line INS64, which combines with SB-ADPCM and its demodulator to transmit 0.05-7 kHz. Analog and digital trans-mission, and direct diagnosis were compared. [Results] (1) Frequency distribution of PVS by digital transmission was similar to direct monitoring, but analysis of analog transmission was impossible. (2)Transmission frequency of 4-7kHz is important because amplitude is often diminished during malfunction. [Conclusion] Frequency analysis of PVS by digital transmission is useful to detect valve malfunction at an early stage.