Abstract
BackgroundPhase-rectified signal averaging (PRSA) was often applied to assess the cardiac vagal modulation. Despite its broad use, this method suffers from the confounding effects of anomalous variants of sinus rhythm. This study aimed to improve the original PRSA method in deceleration capacity (DC) quantification.MethodsThe refined deceleration capacity (DCref) was calculated by excluding from non-vagally mediated abnormal variants of sinus rhythms. Holter recordings from 202 healthy subjects and 51 patients with end-stage renal disease (ESRD) have been used for validity. The DCref was compared to original DC (DCorg) by the area under receiver operating characteristic curve.ResultsExperimental results demonstrate that the original and refined DCs calculated from 24-h, 2-h, and 30-min Holter recordings are significantly lower in patients with ESRD than those in the healthy group. In receiver operating characteristic curve analysis, the DCref provides better performance than the DCorg in distinguishing between the patients with ESRD and healthy control subjects. Furthermore, the refined PRSA technique enhances the low frequency and attenuates high frequency components for spectral analysis in ESRD patients.ConclusionsThe DCref appears to reduce the influence of non-vagally mediated abnormal variants of sinus rhythm and highlighting the pathological influence. DCref, especially assessed from short-term electrocardiography recordings, may be complementary to existing autonomic function assessment, risk stratification, and efficacy prediction strategies.
Highlights
The autonomic nervous system (ANS) plays an essential and important role in maintaining homeostasis for the body’s internal environment via two opposing branches: the sympathetic system and the parasympathetic/vagal system [1, 2]
The deceleration capacity (DC) quantification for Heart rate variability (HRV) signal is essentially based on four steps: (1) definition of anchor points according to certain properties of the heartbeat interval time series; (2) definition of surroundings with certain length around each anchor point; (3) the Phase-rectified signal averaging (PRSA) signal is obtained by averaging the signals within the segments which are aligned at the anchors; and (4) DC is quantified corresponding to a computation of PRSA signal by Haar wavelet analysis [6, 7]
Refined PRSA method clearly enhances the power of low frequency (LF, 0.04–0.15 Hz) and attenuates the power of high frequency (HF, 0.15–0.4 Hz) components for 24-h, 2-h and 30-min ECG recordings, respectively
Summary
The autonomic nervous system (ANS) plays an essential and important role in maintaining homeostasis for the body’s internal environment via two opposing branches: the sympathetic system and the parasympathetic/vagal system [1, 2]. Despite the growing application of DC [8,9,10,11,12,13], the method is affected by one shortcoming: non-vagally mediated abnormal variants of sinus rhythms in heartbeat interval time series are used to quantify DC, confounding the evaluation of cardiac vagal modulation. Previous studies reported that the presence of erratic sinus rhythm, sinus alternans, and their variants, influence values of HRV indices including root-meansquare of successive differences of normal-to-normal interbeat intervals (rMSSD), the percentage of normal-to-normal intervals > 50 ms different from the previous interval (pNN50), and the amount of variance in normal-to-normal intervals at respiratory frequencies (HF, 0.15–0.4 Hz) [14,15,16] This distorted beat-to-beat variability, which does not provide a normal assessment of cardiac autonomic function, leading to paradoxical interpretation between HRV indices and cardiac health. This study aimed to improve the original PRSA method in deceleration capacity (DC) quantification
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