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Sensors 2018, 18(9), 3036;

Improvement of Left Ventricular Ejection Time Measurement in the Impedance Cardiography Combined with the Reflection Photoplethysmography

Department of Computer Science and Information Engineering, Chaoyang University of Technology, Taichung 413, Taiwan
Department of Biomedical Engineering, I-Shou University, Kaohsiung 824, Taiwan
Institute of Medicine, School of Medicine, Chung-Shan Medical University, Taichung 402, Taiwan
Department of Internal Medicine, Chung-Shan Medical University Hospital, Taichung 402, Taiwan
Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung 404, Taiwan
Authors to whom correspondence should be addressed.
Received: 30 July 2018 / Revised: 24 August 2018 / Accepted: 24 August 2018 / Published: 11 September 2018
(This article belongs to the Special Issue Sensors for Biosignal Processing)
Full-Text   |   PDF [3418 KB, uploaded 11 September 2018]   |  


Cardiac stroke volume (SV) is an essential hemodynamic indicator that can be used to assess whether the pump function of the heart is normal. Non-invasive SV measurement is currently performed using the impedance cardiography (ICG). In this technology, left ventricular ejection time (LVET) is an important parameter which can be determined from the ICG signals. However, the ICG signals are inherently susceptible to artificial noise interference, which leads to an inaccurate LVET measurement and then yields an error in the calculation of SV. Therefore, the goal of the study was to measure LVETs using both the transmission and reflection photoplethysmography (PPG), and to assess whether the measured LVET was more accurate by the PPG signal than the ICG signal. The LVET measured by the phonocardiography (PCG) was used as the standard for comparing with those by the ICG and PPG. The study recruited ten subjects whose LVETs were simultaneously measured by the ICG using four electrodes, the reflection PPG using neck sensors (PPGneck) and the transmission PPG using finger sensors (PPGfinger). In each subject, ten LVETs were obtained from ten heartbeats selected properly from one-minute recording. The differences of the measured LVETs between the PCG and one of the ICG, PPGneck and PPGfinger were −68.2 ± 148.6 ms, 4.8 ± 86.5 ms and −7.0 ± 107.5 ms, respectively. As compared with the PCG, both the ICG and PPGfinger underestimated but the PPGneck overestimated the LVETs. Furthermore, the measured LVET by the PPGneck was the closest to that by the PCG. Therefore, the PPGneck may be employed to improve the LVET measurement in applying the ICG for continuous monitoring of SV in clinical settings. View Full-Text
Keywords: stroke volume; left ventricular ejection time; impedance cardiography; photoplethysmography stroke volume; left ventricular ejection time; impedance cardiography; photoplethysmography

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Liu, S.-H.; Wang, J.-J.; Su, C.-H.; Cheng, D.-C. Improvement of Left Ventricular Ejection Time Measurement in the Impedance Cardiography Combined with the Reflection Photoplethysmography. Sensors 2018, 18, 3036.

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