A practical and effective approach for the prevention of ischemia-reperfusion injury after acute myocardial infarction: pressure-regulated tepid blood reperfusion.

BACKGROUND

The prevention of perioperative ischemia-reperfusion injury is of critical importance, and this issue becomes more important in patients undergoing an early emergent revascularization procedure after an acute myocardial infarction. In this study, we sought to test the hypothesis that our simplified pressure-controlled initial reperfusion technique would be protective against ischemia-reperfusion injury in this subgroup of patients.

METHODS

The data of 20 patients (group I) who underwent an emergent coronary artery bypass grafting procedure were analyzed and compared with the results of 37 patients (group II) underwent an innovative reperfusion technique. In group I patients, the operation was carried out using standard techniques. In group II, after the completion of all anastomoses, reperfusion was initiated before rewarming with a pressure of 20 to 25 mmHg and continued for a 2-minute period. Systemic blood pressure was then gradually increased to 40 mmHg and the aortic root was perfused at this pressure for another 2-minute period. Following the completion of the second low-pressure reperfusion period, cardiopulmonary bypass flow was regulated to preoperatively calculated values until systemic temperature reached 37 degrees C.

RESULTS

Both groups showed significant differences in terms of cardiac output, arrhythmia rates, and biochemical parameters. Spontaneous sinus rhythm recurred more frequently in group II (P < .01, 86% versus 45%). Atrial fibrillation attacks were observed in 5 and 3 patients in groups I and II, respectively. All patients were medically converted to sinus rhythm with amiadarone and/or beta-blockers. Persistent electrocardiographic changes indicating postoperative myocardial infarction occurred in 5 patients in group I and in 1 patient in group II (P = .003). Postoperative enzyme levels were found to be lower in group II patients and the differences became statistically significant at the end of 24 hours.

CONCLUSION

These results indicate that our controlled initial reperfusion technique is effective in the prevention of ischemia-reperfusion injury. We advocate the use of this innovative technique as an alternative to complex controlled aortic root reperfusion with the guidance of the early promising results of this study.