Abstract: AIM: To explore the effect of spinal anesthesia on ventricular arrhythmia and involved mechanisms in myocardial ischemia-reperfusion (MIR) rats. METHODS: The rat MIR model was made by occlusion the left anterior descending cor-onary artery for 30 minutes and reperfusion for 45 minutes. Bupivacaine (0.05 mL/100 g, 1 mg/kg) was injected slowly via intrathecal for spinal anes-thesia. The electromyelogram at T2 thoracic spinal cord was recorded. Ventricular arrhythmias, cardiac function, myocardial damage were assessed by electrocardiography, echocardiography and TTC or HE staining. RESULTS: MIR reduced left ventricular short-axis shortening (LVFS) and left ventricular ejection fraction (LVEF), caused myocardial histolog-ical damage and ventricular arrhythmias, promoted spinal electrical discharge frequency and amplitude in T2 dorsal horn. Spinal injection of bupivacaine could significantly reduce spinal cord electrical ac-tivities and eliminate MIR-induced arrhythmias. Moreover, bupivacaine also significantly improved MIR-induced myocardial histological damage and cardiac function inhibition. CONCLUSION: Spinal an-esthesia can reduce ventricular arrhythmias in-duced by MIR. The mechanism may be related to the effect of abolishing spinal nerve excitability. 

Key words: spinal anesthesia, bupivacaine, isch-emia-reperfusion, ventricular arrhythmias, neuro-electrical activity, cardiac function