Autonomic and Peripheral Vascular Effects of Remote Ischemic Preconditioning Assessed by ECG-Gated Digital Pulse Wave Analysis in Healthy Adults

Introduction : Remote ischemic conditioning (RIPC) is a simple, non-invasive procedure in which brief episodes of ischemia and reperfusion, applied to a limb, induce systemic protective mechanisms against ischemic injury to distant organs. Growing experimental evidence suggests that these protective effects may involve complex interactions between neural, hormonal, and endothelial pathways, with modulation of autonomic nervous system activity and vascular function being key contributing factors. Despite increasing interest in the physiological mechanisms underlying RIPC, a comprehensive characterization of its acute effects on autonomic homeostasis and vascular characteristics in humans remains limited. Therefore, this study aimed to investigate the immediate effects of RIPC on autonomic regulation and peripheral vascular stiffness in healthy adults using simultaneous electrocardiography (ECG) and digital pulse wave (DPW) analysis. Methods : Fifteen healthy male participants with normal blood pressure underwent a standardized RIPC protocol consisting of four cycles of upper arm ischemia and reperfusion. A sham remote non-ischemic preconditioning protocol (RNIPC) was used as a control. Five-minute ECG and fingertip DPW recordings were obtained before and immediately after each intervention. Heart rate variability (HRV), large-artery stiffness index (SI), and second-derivative b/a ratio were quantified. Results : RIPC was associated with HRV changes compatible with a shift toward enhanced vagal modulation and/or reduced sympathetic influence, reflected by increases in time-domain, frequency-domain, and non-linear HRV indices, alongside reductions in heart rate and stress index. Peripheral vascular stiffness decreased, and the b/a ratio became more negative. Conclusions : In this exploratory study, acute RIPC was associated with HRV changes compatible with enhanced vagal modulation and/or reduced sympathetic influence, together with reductions in peripheral vascular stiffness indices. ECG-gated DPW analysis provides a sensitive, non-invasive approach for detecting these physiological adaptations in humans.