Protection of acutely ischemic myocardium by controlled reperfusion

Controlled Reperfusion Versus Conventional Treatment of the Acutely Ischemic Limb

Background—

Amputation rates and mortality in patients with severe acute limb ischemia remain high. The protective effect of controlled reperfusion (CR) on tissue damage because of local and systemic reperfusion injury is unclear.

Methods and Results—

A total of 174 patients from 14 centers were randomized between conventional treatment (CT) by thrombembolectomy and normal blood reperfusion and thrombembolectomy followed by CR. The primary end point was amputation-free survival (AFS) after 4 weeks (CT, 82.4%; CR, 82.6%). Secondary end points were AFS (CT, 62.4%; CR, 63.1%) and overall survival (CT, 71.6%; CR, 76.3%) after 1 year. Analysis of the prognostic effects of preoperative factors revealed a strong adverse effect of bilateral involvement on AFS. In the subgroup with unilateral ischemia (n=160), age >80 years and central localization of the occlusion had independent negative prognostic effects on AFS. In the per-protocol population of 104 patients with unilateral ischemia, treatment per protocol, and successful revascularization, amputation or death within 4 weeks occurred in only 8% as compared with 33% in patients not fulfilling these criteria. No differences between treatment groups CT and CR were found, neither overall nor in the per-protocol population nor in patient subgroups defined by other pre- and intraoperative factors.

Conclusions—

Similar AFS in patients with CT or with CR was observed in this large randomized multicenter trial.

Clinical Trial Registration—

URL: http://www.drks.de . Unique identifier: DRKS00000579.

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.

Insulin-like growth factor-1 protects ischemic murine myocardium from ischemia/reperfusion associated injury

INTRODUCTION

Ischemia/reperfusion occurs in myocardial infarction, cardiac dysfunction during sepsis, cardiac transplantation and coronary artery bypass grafting, and results in injury to the myocardium. Although reperfusion injury is related to the nature and duration of ischemia, it is also a separate entity that may jeopardize viable cells and ultimately may impair cardiac performance once ischemia is resolved and the organ heals.

METHOD

The present study was conducted in an ex vivo murine model of myocardial ischemia/reperfusion injury. After 20 min of ischemia, isolated hearts were perfused for up to 2 hours with solution (modified Kreb's) only, solution plus insulin-like growth factor (IGF)-1, or solution plus tumor necrosis factor (TNF)-alpha. Cardiac contractility was monitored continuously during this period of reperfusion.

RESULTS

On the basis of histologic evidence, IGF-1 prevented reperfusion injury as compared with TNF-alpha; TNF-alpha increased perivascular interstitial edema and disrupted tissue lattice integrity, whereas IGF-1 maintained myocardial cellular integrity and did not increase edema. Also, there was a significant reduction in detectable creatine phosphokinase in the perfusate from IGF-1 treated hearts. By recording transduced pressures generated during the cardiac cycle, reperfusion with IGF-1 was accompanied by markedly improved cardiac performance as compared with reperfusion with TNF-alpha or modified Kreb's solution only. The histologic and functional improvement generated by IGF-1 was characterized by maintenance of the ratio of mitochondrial to nuclear DNA within heart tissue.

CONCLUSION

We conclude that IGF-1 protects ischemic myocardium from further reperfusion injury, and that this may involve mitochondria-dependent mechanisms.