A Temporal Reliability and Sustainability Score Framework for Ranking Heart Rate Variability Metrics During Pharmacological Autonomic Blockade in Rats

A new study establishes a reliability and sustainability score framework to rank Heart Rate Variability (HRV) metrics during pharmacological autonomic blockade in rats. HRV is a crucial non-invasive method for assessing the autonomic nervous system (ANS). The research introduces the sustainability score to determine which HRV parameters best reflect ANS modulation following drug-induced blockade.

Ten male Sprague-Dawley rats underwent implantation of ECG electrodes. Following recovery, rats were subjected to randomized atropine (1 mg/kg, intraperitoneal) and propranolol (10 mg/kg, intraperitoneal) sessions, with at least a 3-day interval between sessions. Baseline ECGs were recorded for 30 minutes before each session, followed by 90-minute post-drug ECG recordings. HRV parameters were analyzed in sequential 15-minute and 30-minute segments.

Reliability was evaluated using average p-values across post-drug segments and a sustainability score. The sustainability score is defined as the number of segments that showed significant differences from baseline. The study found that after atropine administration, HF Power exhibited the strongest rapid parasympathetic response in 15-minute segments, with the lowest average p-value (0.1476) and the highest sustainability score (4).

RSA had a p-value of 0.16148 and a sustainability score of 4. HFn was less reliable in 15-minute segments (p=0.23147; score=2) but became the most reliable parasympathetic-related metric in 30-minute segments (p=0.0001; score=3).

In the propranolol group, SI was the most reliable sympathetic-related metric, demonstrating significant differences in both 15-minute (p=0.18225; score=2) and 30-minute (p=0.0393; score=2) segments. Additionally, SD2/SD1 showed the strongest 30-minute sympathovagal-balance response (p=0.0200; score=3).

The authors conclude that HF Power is recommended for rapid assessment of parasympathetic activity in short windows, HFn is suitable for longer-window parasympathetic evaluation, SI is appropriate for sympathetic assessment, and SD2/SD1 is ideal for analyzing sympathovagal balance over a 30-minute period. The sustainability scoring framework offers a structured approach for selecting ECG-derived autonomic markers.