Respiratory sinus arrhythmia is reduced after pulmonary vein isolation in patients with paroxysmal atrial fibrillation

Impact of Pulsed-Field Ablation on Intrinsic Cardiac Autonomic Nervous System After Pulmonary Vein Isolation

BACKGROUND

Although the autonomic reaction such as bradycardia is observed frequently during pulsed-field ablation (PFA)-guided pulmonary vein isolation (PVI), its mechanism and effect on the adjacent intrinsic cardiac autonomic nervous system (ICANS) are unclear.

OBJECTIVES

This study aimed to reveal the clinical impact of PFA on ICANS by investigating the serum S100 increase (ΔS100), a well-known denervation relevant biomarker.

METHODS

Pre- and postprocedural serum S100 analyses were systematically conducted in patients undergoing PVI using either the pentaspline PFA or cryoballoon ablation (CBA) system. ΔS100 release kinetics were compared between both technologies. Cerebral magnetic resonance imaging was conducted to eliminate the effect of central nervous system release.

RESULTS

A total of 97 patients (PFA: n = 54 and CBA: n = 43) were enrolled. Overall S100 increased in both groups with a lower amount in PFA (0.035 μg/L; IQR: 0.02-0.063 μg/L) compared with CBA (0.12 μg/L; IQR: 0.09-0.17 μg/L; P < 0.0001). In cerebral magnetic resonance imaging, silent emboli were detected in 10 patients (18.5%) in PFA and 7 patients (16.3%) in CBA (P = 0.773). Even after excluding patients with cerebral emboli, ΔS100 was lower in PFA. During PFA PVI, 30 patients (56%) demonstrated transient bradycardia in 70 of 210 PVs (35%). ΔS100 was similar between patients with or without transient bradycardia.

CONCLUSIONS

We report a significantly lower S100 release following PFA PVI vs CBA PVI even if silent cerebral emboli were excluded. Notably, vagal response during PFA was not associated with S100 release. These observations are in line with lower nervous tissue destruction of PFA compared with CBA.

Autonomic Nervous System and Cardiac Metabolism: Links Between Autonomic and Metabolic Remodeling in Atrial Fibrillation

Simultaneous activation of the sympathetic and parasympathetic nervous systems is crucial for the initiation of paroxysmal atrial fibrillation (AF). However, unbalanced activation of the sympathetic system is characteristic of autonomic remodeling in long-standing persistent AF. Moreover, the adrenergic activation-induced metabolic derangements provide a milieu for acute AF and promote the transition from the paroxysmal to the persistent phase of AF. On the other hand, cholinergic activation ameliorates the maladaptive metabolic remodeling in the face of metabolic challenges. Selective inhibition of the sympathetic system and restoration of the balance of the cholinergic system by neuromodulation is emerging as a novel nonpharmacologic strategy for managing AF. This review explores the link between cardiac autonomic and metabolic remodeling and the potential roles of different autonomic modulation strategies on atrial metabolic aberrations in AF.

Early detection of the impact of combined taxane and carboplatin treatment on autonomic nerves in patients with cervical cancer: Measurement of heart rate variability

Background: Previous studies have shown that heart rate variability (HRV) analysis is a sensitive indicator of chemotherapy-induced cardiotoxicity. However, most studies to date have observed long-term effects using long-term analyses. The main purpose of this study was to evaluate the acute effect of chemotherapy on the cardiac autonomic nervous system (ANS) in patients with cervical cancer (CC) by examining short-term HRV. Methods: Fifty patients with CC admitted to the Department of Gynecology and Oncology of the First Affiliated Hospital of Bengbu Medical College were enrolled in the study. Based on their chemotherapy regimens, the patients were divided into a DC group (docetaxel + carboplatin) and a TC group (paclitaxel + carboplatin). A 5-min resting electrocardiogram (ECG) was collected before and the day after chemotherapy: the time domain (standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive differences (RMSSD)) and frequency domain (low-frequency power (LF), high-frequency power (HF), and (LF/HF)) parameters were analyzed, and the differences before and after chemotherapy were compared. Results: The results showed that SDNN, RMSSD and HF were significantly higher in the DC and TC groups after chemotherapy than before (p < 0.05, Cohen's d > 0.5). In addition, LF was significantly higher after TC than before chemotherapy (p < 0.05, Cohen's d > 0.3), and LF/HF was significantly lower after DC than before chemotherapy (p < 0.05, Cohen's d > 0.5). Conclusion: Chemotherapy combining taxane and carboplatin can increase the HRV of CC patients in the short term, and HRV may be a sensitive tool for the early detection of chemotherapy-induced cardiac ANS perturbations.

Neuroscientific therapies for atrial fibrillation

The cardiac autonomic nervous system (ANS) plays an integral role in normal cardiac physiology as well as in disease states that cause cardiac arrhythmias. The cardiac ANS, comprised of a complex neural hierarchy in a nested series of interacting feedback loops, regulates atrial electrophysiology and is itself susceptible to remodelling by atrial rhythm. In light of the challenges of treating atrial fibrillation (AF) with conventional pharmacologic and myoablative techniques, increasingly interest has begun to focus on targeting the cardiac neuraxis for AF. Strong evidence from animal models and clinical patients demonstrates that parasympathetic and sympathetic activity within this neuraxis may trigger AF, and the ANS may either induce atrial remodelling or undergo remodelling itself to serve as a substrate for AF. Multiple nexus points within the cardiac neuraxis are therapeutic targets, and neuroablative and neuromodulatory therapies for AF include ganglionated plexus ablation, epicardial botulinum toxin injection, vagal nerve (tragus) stimulation, renal denervation, stellate ganglion block/resection, baroreceptor activation therapy, and spinal cord stimulation. Pre-clinical and clinical studies on these modalities have had promising results and are reviewed here.