Contactless Measurement of Human Systolic Time Intervals based on Differential Doppler Cardiogram in Clinical Environment

As the most important organ of human body, heart has many monitoring indicators to assist the clinical diagnosis. Of major relevance in providing crucial information regarding cardiovascular state are heart systolic time intervals. While the existing measurement technologies are costly, complicated to operate, and also require contact sensors. Based on the human cardiovascular model and principle of Doppler cardiogram, the differential Doppler cardiogram (D-DCG) carries the aortic pressure information by which the STIs can be calculated. A 24-GHz digital dc-tuning Doppler radar sensor (DRS) has been implemented to detect the accurate D-DCG. To assess the feasibility of contactless measurement of the STIs by DRS, clinical experiments are carried out in operation theatre. The pre-ejection period and the left ventricular ejection time estimation results reached 95.23% and 93.12% accuracy, which indicates the proposed method has great potential to be used for STIs estimation and could be convenient for patient home monitoring.