Objective: This study investigates the cardioprotective effects of focused ultrasound stimulation (FUS) as a novel, noninvasive intervention for mitigating acute myocardial ischemia/reperfusion (I/R) injury.

Methods: In rat I/R models (30-min left anterior descending coronary artery (LAD) occlusion followed by 2-/24-h reperfusion), FUS was applied to the right cervical vagus nerve during early reperfusion (10-60 min post-reperfusion). The effects of FUS were assessed by analyzing inflammatory markers, arrhythmia incidence, pathological changes, echocardiographic parameters, pro-/anti-oxidative biomarkers, myocardial fibrosis, and infarct size. To elucidate the underlying mechanism, vagotomy and atropine administration were performed.

Results: FUS significantly reduced heart rate and inflammation in the 2-h reperfusion model. Compared to the I/R group, the I/R + FUS group exhibited markedly decreased premature ventricular contractions (221.00 ± 166.93 vs 83.11 ± 34.08, p < 0.05), ventricular tachycardia and ventricular fibrillation (16.67 ± 10.68 vs. 3.67 ± 3.24, p < 0.01), and arrhythmia scores during reperfusion (2.44 ± 1.13 vs. 0.67 ± 0.50, p < 0.01). In the 24-h reperfusion model, FUS significantly reduced myocardial fibrosis and infarct size (infarct size/area at risk 49.60 ± 9.17% vs. 20.73 ± 4.91%, p < 0.001) and preserved left ventricular ejection fraction (35.68 ± 9.95% vs 56.73 ± 2.64%, p < 0.001). The protective effects of FUS were abolished by vagotomy or atropine, suggesting the cholinergic anti-inflammatory pathway as a potential mechanism.

Conclusions: Targeted FUS neuromodulation exerts acute and sustained cardioprotection against I/R injury primarily through cholinergic anti-inflammatory mechanisms, offering a safer and more accessible alternative to traditional treatments.