Detection of opening and closing of the aortic valve using impedance cardiography and its validation by echocardiography
Detection of opening and closing of the aortic valve using impedance cardiography and its validation by echocardiography
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DOI：
10.1088/2057-1976/aa8bf5
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发表时间：
2018-01-01
影响因子：
1.4
通讯作者：
Hardas, S. P.
中科院分区：
文献类型：
--
作者：
Bagal, Uttam R.;Pandey, Prem C.;Hardas, S. P.
阻抗心动图是一种无创技术，用于估计脑卒中容量、收缩时间间隔和其他一些心血管指标。这些估计需要准确无误地检测阻抗心电图（ICG）的B点、C点和X点，分别作为主动脉瓣开度、主动脉血流速峰值和主动脉瓣关闭的标志。基于对ICG波形的形态学变化的经验检查，开发了一种自动拍对拍检测这些点的技术。它使用基于小波的去噪来抑制呼吸伪影，以避免在录制过程中对呼吸的限制。它以心电R峰为参考点，避免了周期间的模糊和多个时域波形特征，减少了形态学变化带来的误差。该技术通过同时获取的ICG、ECG和多普勒超声心动图记录进行评估，这些记录来自健康正常和心血管疾病的受试者。与以前的方法相比，该方法检测的点具有低偏差和精度误差。以多普勒超声心动图测量值为参考，估计R-C、R-B、R-X、B-X区间的差均值R-R区间分别为0.5%、0.3%、0.5%、3.0%。差异对应的标准差分别为1.3%、1.3%、5.8%和6.0%。提出的技术可能有助于提高阻抗心动图诊断心血管疾病的可接受性。
Impedance cardiography is a noninvasive technique for estimation of stroke volume, systolic time intervals, and some other cardiovascular indices. These estimations require error-free detection of the B, C, and X points of impedance cardiogram (ICG), as markers of aortic valve opening, peak aortic blood velocity, and aortic valve closure, respectively. Based on an empirical examination of the morphological variations in the ICG waveforms, a technique for automatic beat-to-beat detection of these points is developed. It uses wavelet-based denoising for suppression of respiratory artifacts to avoid restrictions on breathing during the recording. It uses R peaks of ECG as reference points to avoid inter-cycle smearing and multiple time-domain waveform features to reduce errors due to morphological variations. The technique is evaluated on simultaneously acquired and time-aligned ICG, ECG, and Doppler echocardiogram recordings from subjects with normal-health and subjects with cardiovascular disorders. Compared to the earlier techniques, the proposed technique detects the points with low bias and precision errors. The means of differences, as referred to the mean R-R interval, in the estimation of R-C, R-B, R-X, and B-X intervals with the corresponding measurements from Doppler echocardiograms as the reference were 0.5%, 0.3%, 0.5% and 3.0% respectively. The corresponding standard deviations of differences were 1.3%, 1.3%, 5.8% and 6.0%. The proposed technique may help in improving the acceptability of impedance cardiography for diagnosis of cardiovascular disorders.