Assessment of Autonomic Function by Phase Rectification of RR-Interval Histogram Analysis in Chagas Disease

Abstract

BackgroundIn chronic Chagas disease (ChD), impairment of cardiac autonomic function bears prognostic implications. Phase‑rectification of RR-interval series isolates the sympathetic, acceleration phase (AC) and parasympathetic, deceleration phase (DC) influences on cardiac autonomic modulation.ObjectiveThis study investigated heart rate variability (HRV) as a function of RR-interval to assess autonomic function in healthy and ChD subjects.MethodsControl (n = 20) and ChD (n = 20) groups were studied. All underwent 60-min head-up tilt table test under ECG recording. Histogram of RR-interval series was calculated, with 100 ms class, ranging from 600–1100 ms. In each class, mean RR-intervals (MNN) and root-mean-squared difference (RMSNN) of consecutive normal RR-intervals that suited a particular class were calculated. Average of all RMSNN values in each class was analyzed as function of MNN, in the whole series (RMSNNT), and in AC (RMSNNAC) and DC (RMSNNDC) phases. Slopes of linear regression lines were compared between groups using Student t-test. Correlation coefficients were tested before comparisons. RMSNN was log-transformed. (α < 0.05).ResultsCorrelation coefficient was significant in all regressions (p < 0.05). In the control group, RMSNNT, RMSNNAC, and RMSNNDC significantly increased linearly with MNN (p < 0.05). In ChD, only RMSNNAC showed significant increase as a function of MNN, whereas RMSNNT and RMSNNDC did not.ConclusionHRV increases in proportion with the RR-interval in healthy subjects. This behavior is lost in ChD, particularly in the DC phase, indicating cardiac vagal incompetence.

Dynamic Coupling Between Ventricular Repolarization Duration and RR:Interval Phase:Rectification Analysis in Chagas Disease

“…Indeed, VRD offset assessed either at the peak of the T-wave or the inflexion point after the peak show high correlation with the VRD measured at the end of the T-wave, validating this measurement [14]. The performance of HRV time domain parameters has been assessed in a previous study, by grouping RRintervals in different histogram classes [15]. Furthermore, the capability of RR-intervals to accelerate or to decelerate allowed isolating sympathetic (AC) and parasympathetic (DC) phase contributions on heart rate variation, respectively.…”

“…Furthermore, the capability of RR-intervals to accelerate or to decelerate allowed isolating sympathetic (AC) and parasympathetic (DC) phase contributions on heart rate variation, respectively. Thus, by comparing control and ChD groups, the study introduced novel information that brought insights into the dependence of heart rate on autonomic modulation in a population of chronic ChD [15]. Salles et al [4] were the first to describe the prognostic importance of ECG parameters of ventricular repolarization in patients with ChD.…”

Dysautonomic Arrhythmogenesis: A Working Hypothesis in Chronic Chagas Cardiomyopathy

“…Their effects on the recovery of excitability result in an increase of the dispersion of action potential duration to a critical level 39 during residual sympathetic activation and increase the propensity to ventricular arrhythmias. [33][34][35]40 Although it is difficult to determine the independent effects of impaired cardiac autonomic modulation, it certainly influences the recovery of excitability , as recently suggested by myocardial scintigraphy studies. 21 This is certainly an area of research that merits further investigation.…”

Stratification of the level of aerobic fitness based on heart rate variability parameters in adult males at rest

“…Particularly the decelerating capacity index is being useful to predict mortality after myocardial infarction (Bauer et al, 2009), to estimate physical conditioning (Nasario-Junior et al, 2014;Nasario-Junior et al, 2015a) and autonomic control status in Chagas disease patients (Nasario-Junior et al, 2015b). On the other hand, it is still unknown how these parameters relate with VO2max.…”