Continuous Peripheral Electrical Nerve Stimulation Improves Cardiac Function via Autonomic Nerve Regulation in MI Rats

Background Peripheral electrical nerve stimulation (PENS) reportedly improves cardiac function after myocardial ischemia (MI) by rebalancing the cardiac autonomic nervous system. The dynamic and continuous influence of the PENS on autonomic and cardiac functioning based on cardiac self-repair is not well understood. Objective This study aimed to explore the correlations between autonomic nervous balance and functional cardiac repair after MI and to clarify the optimal acupoint selection and time course for PENS. Methods The activity of the superior cervical cardiac sympathetic nerve (SN) and vagus nerve (VN) was recorded to reflect the autonomic tone directly. The Millar pressure-volume loop system was used for LV diastolic and systolic functioning. Noninvasive continuous ECG and echocardiography were performed to analyse HR, HRV, and LV function. The effect of continuous PENS (cPENS) or instant PENS (iPENS) on autonomic and cardiac indications was tested. Results SN activity and VN activity increased as compensatory self-regulation on days 7 and 14 post-MI, followed by an imbalance of autonomic tone and cardiac dysfunction on day 28. cPENS-PC6 maintained autonomic hyperexcitability, improved myocardial systolic and diastolic abilities, and reduced myocardial fibrosis on day 28 post-MI, whereas cPENS-ST36 had a limited effect. Both iPENS-PC6 and iPENS-ST36 improved the autonomic and cardiac function of rats in the cPENS groups. Conclusion Rats showed autonomic fluctuations and cardiac dysfunction 28 days post-MI. cPENS produced sympathomimetic action to sustain cardiac self-compensation, but with acupoint specificity. Based on cPENS, iPENS evoked autonomic regulation and cardiac benefits without acupoint differentiation.