Abstract
Sudden cardiac death caused by ventricular arrhythmias is among the leading causes of mortality, with approximately half of all deaths attributed to heart disease worldwide. Periodic repolarization dynamics (PRD) is a novel marker of repolarization instability and strong predictor of death in patients post-myocardial infarction that is believed to occur in association with low-frequency oscillations in sympathetic nerve activity. However, this hypothesis is based on associations of PRD with indices of sympathetic activity that are not directly linked to cardiac function, such as muscle vasoconstrictor activity and the variability of cardiovascular autospectra. In this review article, we critically evaluate existing scientific evidence obtained primarily in experimental animal models, with the aim of identifying the neuronal networks responsible for the generation of low-frequency sympathetic rhythms along the neurocardiac axis. We discuss the functional significance of rhythmic sympathetic activity on neurotransmission efficacy and explore its role in the pathogenesis of ventricular repolarization instability. Most importantly, we discuss important gaps in our knowledge that require further investigation in order to confirm the hypothesis that low frequency cardiac sympathetic oscillations play a causative role in the generation of PRD.
Highlights
INTRODUCTIONSpecialty section: This article was submitted to Cardiac Electrophysiology, a section of the journal Frontiers in Physiology
Specialty section: This article was submitted to Cardiac Electrophysiology, a section of the journal Frontiers in PhysiologyReceived: 19 December 2019 Accepted: 02 March 2020 Published: 18 March 2020Citation: Ang R and Marina N (2020) Low-Frequency Oscillations in Cardiac Sympathetic Neuronal Activity
The discovery of periodic repolarization dynamics (PRD) as a novel marker of cardiac sympathetic nerve (CSN) traffic and strong predictor of death has recently reignited the interest in the phenomenon of sympathetic rhythmicity
Summary
Specialty section: This article was submitted to Cardiac Electrophysiology, a section of the journal Frontiers in Physiology. Recent studies have shown that ventricular repolarization instability after an acute myocardial infarction (MI) exhibits a pronounced rhythmic pattern that is believed to mimic the characteristic low-frequency (LF) oscillations in sympathetic efferent activity (Rizas et al, 2014, 2017; Pueyo et al, 2016). This electrophysiological phenomenon has been termed periodic repolarization dynamics (PRD) and it can be measured non-invasively from the vector angle of the electrocardiogram (ECG) T wave (Rizas et al, 2014). We identify important gaps in our knowledge that need to be addressed in future studies
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