Lidocaine protects against myocardial ischemia-reperfusion injury in anesthetized rabbits

In order to investigate the myocardial protective effect of lidocaine, we used a model of myocardial ischemia in anesthetized rabbits to study the effect on infarct size of lidocaine infusion during the first 30 minutes of reperfusion after myocardial ischemia. Japanese white rabbits anesthetized with nitrogen oxide, oxygen and pancuronium were placed on their sides. The left anterior descending coronary artery was exposed via left thoracotomy. Following a 30-minute ischemia to the coronary artery, a 30-minute infusion of lidocaine at 1.0mg/kg/h or physiological saline was started immediately after the initiation of 120-minute reperfusion. During the experiment, systemic blood pressure was continuously monitored using a catheter placed in the femoral artery, and serum lidocaine concentration was determined periodically. At the end of the experiment, the heart was isolated and treated with Evans blue dye to identify the area at risk (AAR) and the non-risk area. The areas of infarction and the risk area were determined using 1% 2,3,5-triphenyltetrazolium chloride (TTC). Although the systemic arterial pressure at 10 and 20 minutes after the coronary ligation was lower than baseline, no significant differences were observed between the lidocaine and saline groups. The AAR and non-risk areas did not differ significantly between the lidocaine and saline groups. The percentage of infarct size per AAR was 14.4% lower in animals receiving lidocaine infusion during reperfusion than in those receiving saline. These findings indicate that high-dose lidocaine infusion protects the myocardium against ischemia-reperfusion injury without affecting blood pressure during reperfusion.