Contactless Measurement of Human Systolic Time Intervals Based on Doppler Cardiograms in Clinical Environment

Abstract

As the most important organ of human body, heart has many measures and indicators to assess the cardiac function in clinic. Ventricular systolic time intervals (STIs) are of major relevance in providing crucial information regarding cardiovascular state. However, 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 (DCG), the differential DCG (D-DCG) and quadratic D-DCG (QD-DCG) carry the aortic pressure (AP) 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 DCGs. To assess the feasibility of contactless measurement of the STIs by DRS, clinical experiments and evaluations are carried out in the operation theater (OT). The preejection period (PEP) and the left ventricular ejection time (LVET) estimation results reached 95.23% and 93.12% accuracy, respectively, which indicates that the proposed method has great potential to be used for STIs estimation and could be convenient for patient home monitoring.