Contactless multiscale measurement of cardiac motion using biomedical radar sensor.

Introduction: A contactless multiscale cardiac motion measurement method is proposed using impulse radio ultra-wideband (IR-UWB) radar at a center frequency of 7.29 GHz. Motivation: Electrocardiograph (ECG), heart sound, and ultrasound are traditional state-of-the-art heartbeat signal measurement methods. These methods suffer from defects in contact and the existence of a blind information segment during the cardiogram measurement. Methods: Experiments and analyses were conducted using coarse-to-fine scale. Anteroposterior and along-the-arc measurements were taken from five healthy male subjects (aged 25-43) when lying down or prone. In every measurement, 10 seconds of breath-holding data were recorded with a radar 55 cm away from the body surface, while the ECG was monitored simultaneously as a reference. Results: Cardiac motion detection from the front was superior to that from the back in amplitude. In terms of radar detection angles, the best cardiac motion information was observed at a detection angle of 120°. Finally, in terms of cardiac motion cycles, all the ECG information, as well as short segments of cardiac motion details named blind ECGs segments, were detected. Significance: A contactless and multiscale cardiac motion detection method is proposed with no blind detection of segments during the entire cardiac cycle. This paves the way for a potentially significant method of fast and accurate cardiac disease assessment and diagnosis that exhibits promising application prospects in contactless online cardiac monitoring and in-home healthcare.

Numerical prediction of thrombosis risk in left atrium under atrial fibrillation.

The remodeling of the left atrial morphology and function caused by atrial fibrillation (AF) can exacerbate thrombosis in the left atrium (LA) even spike up the risk of stroke within AF patients. This study explored the effect of the AF on hemodynamic and thrombosis in LA. We reconstructed the patient-specific anatomical shape of the LA and considered the non-Newtonian property of the blood. The thrombus model was applied in the LA models to simulate thrombosis. Our results indicate that AF can aggravate thrombosis which mainly occurs in the left atrial appendage (LAA). Thrombosis first forms on the LAA wall then expands toward the internal LAA. The proposed computational model also shows the potential application of numerical analyses to help assess the risk of thrombosis in AF patients.