Proposing Non-Invasive Clip Electrodes to Obtain Noise-Free Electrocardiogram of Rats and Comparing Its HRV Parameters With Human

Background: Both electrocardiogram (ECG) and heart rate variability (HRV) are hallmark markers of cardiovascular pathophysiology, and rats are readily used for understanding various cardiovascular abnormalities ailing humans. Aims: The current research has two proposals: testing the non-invasive, reusable limb electrodes made from stainless steel paper binder clip for recording rat ECG, which is like clinical clamp electrodes used for humans, and analyzing the correlation amongst HRV parameters in both rats and humans thereby evaluating whether rat and human cardiac physiology shares analogy in electrical conduction and sympathovagal modulation. Methods: Single-channel digital bipolar ECG signals (250 samples/second) from rats and human subjects were recorded with the help of a two-channel Biopac amplifier and its associated software (Biopac Inc., USA). The ECG signals of rats were recorded with the laboratory-made stainless steel clip electrodes and the conventional needle electrodes. In contrast, the surface ECG was recorded from human subjects with the clinical clamp electrodes. Results: Smooth rat ECG signals with well-demarcated cliffs and troughs having patterns resembling human ECG waveforms were obtained using novel clip electrodes. In addition, the correlation amongst several HRV parameters in rats, like RR interval with heart rate and SD2 with RMSSD, agreed with the one seen in humans. Conclusion: The ECG waveform acquisitions uphold the utility of novel clip electrodes. The HRV correlation matrix heatmap of rats, when compared to humans, showcased reasonable similarity. Thus, the utility of rats as model animals and the use of ethical laboratory procedures in understanding human cardiac pathophysiology is reaffirmed.