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. 2019 Aug 22:10:1057.
doi: 10.3389/fphys.2019.01057. eCollection 2019.

Comparison of Different Methods for Estimating Cardiac Timings: A Comprehensive Multimodal Echocardiography Investigation

Parastoo Dehkordi  1 , Farzad Khosrow-Khavar  2 , Marco Di Rienzo  3 , Omer T Inan  4 , Samuel E Schmidt  5 , Andrew P Blaber  6 , Kasper Sørensen  5 , Johannes J Struijk  5 , Vahid Zakeri  2 , Prospero Lombardi  3 , Md Mobashir H Shandhi  4 , Mojtaba Borairi  7 , John M Zanetti  8 , Kouhyar Tavakolian  6   9
Affiliations

Comparison of Different Methods for Estimating Cardiac Timings: A Comprehensive Multimodal Echocardiography Investigation

Parastoo Dehkordi et al. Front Physiol. .

Abstract

Cardiac time intervals are important hemodynamic indices and provide information about left ventricular performance. Phonocardiography (PCG), impedance cardiography (ICG), and recently, seismocardiography (SCG) have been unobtrusive methods of choice for detection of cardiac time intervals and have potentials to be integrated into wearable devices. The main purpose of this study was to investigate the accuracy and precision of beat-to-beat extraction of cardiac timings from the PCG, ICG and SCG recordings in comparison to multimodal echocardiography (Doppler, TDI, and M-mode) as the gold clinical standard. Recordings were obtained from 86 healthy adults and in total 2,120 cardiac cycles were analyzed. For estimation of the pre-ejection period (PEP), 43% of ICG annotations fell in the corresponding echocardiography ranges while this was 86% for SCG. For estimation of the total systolic time (TST), these numbers were 43, 80, and 90% for ICG, PCG, and SCG, respectively. In summary, SCG and PCG signals provided an acceptable accuracy and precision in estimating cardiac timings, as compared to ICG.

Keywords: cardiac time intervals; echocardiography; impedance cardiography (ICG); left ventricular ejection time (LVET); phonocardiography (PCG); pre-ejection period (PEP); seismocardiography (SCG).

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Figures

Figure 1
Figure 1
Simultaneous sample recordings of ECG, SCG, ICG, and PCG signals captured from a 40-year-old male participant in the supine position. The SCG MC and SCG MO points correspond to mitral valve closure and opening; the SCG AC and SCG AO points corresponded to the aortic valve closure and opening. ICG B point corresponded to aortic valve opening and ICG X point to aortic valve closure. EMD, PEP, TST and LVET systolic time intervals are also illustrated. S1 and S2 waves on PCG corresponded to mitral and aortic valve closure, respectively.
Figure 2
Figure 2
Echocardiogram images captured using (A) M-mode, (B) Doppler flow, and (C) TDI modalities. AVO and AVC stand for aortic valve opening and closure. MVO and MVC stand for mitral valve opening and closure. Max and min subscripts represent the start and the end of the echocardiographic ranges.
Figure 3
Figure 3
The boxplot shows the values of (A) PEP estimated from ICG and SCG and (B) TST estimated from ICG, PCG, and SCG compared to the measurements from echocardiography. Lower quartile, median, and upper quartile values were displayed as bottom, middle, and top horizontal line of the boxes. Whiskers were used to represent the most extreme values within 1.5 times the interquartile range from the quartile. Outliers (data with values beyond the ends of the whiskers) were displayed as dots.
Figure 4
Figure 4
Bland and Altman plots for assessing the agreement between (A) PEPecho and PEPicg, (B) PEPecho and PEPscg, (C) LVETecho and LVETicg, and (D) LVETecho and LVETscg.
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