An Effective Approach to Autonomously Extract D/S Indicator From Heart Sound

D/S indicator which is the duration time ratio of heart diastole and systole is used to evaluate whether the blooding time in heart diastole is long enough, but how to extract the D/S indictor from heart sound autonomously, effectively and noninvasively is still a big challenge. This paper proposed an effective approach to autonomously and noninvasively extract D/S indicator from heart sound. Firstly, the heart sound was recorded by a noninvasive physiological recording instrument. Secondly, the heart sound pre-processing, envelope extraction, choosing the adaptive threshold value (THV) line and identification the first and second heart sounds were performed in sequence. Finally, to extract the D/S indicator. In the test, 320 heart sound signals were extracted the D/S indicators using the proposed approach, with the accuracy of 309/320 comparing with the synchronous electrocardiogram (ECG) signals, which proved the effectiveness of approach. 90 heart sound signals with 30 patients with congenital heart disease, 30 normal people and 30 athletes were tested to extract D/S indicator without ECG signals as reference, then, the D/S indicators were estimated and divided into different levels. To count the number at different D/S levels, the statistics shew that the D/S indicators were closely related to people’s heart health, which was to say that the proposed approach could be used to autonomously extract the D/S indicator.