The role of the autonomic nervous system in the patterns of heart rate fragmentation

Author(s)

da Silva, Thais Marques ; Aguiar Silva, Carlos Alberto ; Salgado, Helio Cesar ; Fazan Jr, Rubens ; Virgilio Silva, Luiz Eduardo

• Document type: Journal article
• Source: Biomedical Signal Processing and Control; v. 67, p. 7-pg., 2021-03-02.

Abstract

Although rapid oscillations in heart rate (HR) are commonly attributed to vagal modulation of the heart, an ultrarapid pattern of HR variation has recently been studied and named heart rate fragmentation (HRF). Objective: Considering that the underlying mechanisms of HRF are unknown, this study aims to evaluate the influence of the autonomic nervous system on HRF in rats. Methods: Electrocardiogram recordings were performed in awake rats at baseline conditions and after selective or combined pharmacological autonomic blockade. Series of RR intervals were calculated and HRF indices were computed, namely percentage of inflection points (PIP), percentage of patterns with zero (W-0), one (W-1), two (W-2) or three (W-3) inflection points, and percentage of patterns with only hard (W-H), soft (W-S) or mixed (W-M) inflection points. Moreover, the correlations between HRF indices and several important heart rate variability (HRV) indices were estimated. Results: PIP and W3 increased while W-1 decreased after autonomic blockade (sympathetic, parasympathetic or combined). In contrast, the parasympathetic blockade noticeably decreased hard (W-H) and increased soft (W-S) HR transitions. Except for W-0, HRF patterns grouped by the number of inflection points were not correlated to any studied HRV index. In contrast, patterns grouped by the type of inflection points are highly correlated to magnitude-dependent HRV indices. Conclusion: Cardiac sympathetic and parasympathetic influences similarly decrease HRF, while the parasympathetic control markedly increases the hard HR inflection points. Further studies should be conducted to verify whether the autonomic nervous system plays a different role in diseases marked by autonomic imbalance. (AU)

• FAPESP's process: 13/20549-7 - New insights in cardiovascular regulation under physiological and pathophysiological condition
• Grantee: Helio Cesar Salgado
• Support Opportunities: Research Projects - Thematic Grants