Abstract

Introduction

Regional Myocardial Hypothermia (RMH)

RMH after the onset of ischemia

Summary and Conclusions

References

Discussion
Board

We tested the potential of mild regional myocardial hypothermia (RMH) to protect ischemic myocardium in several studies using open-chest, anesthetized rabbits subjected to coronary artery occlusion (CAO) and 3 hours of reperfusion. Heart temperature was reduced by topically cooling the surface of the heart using an ice/water filled bag. Temperature was monitored by a thermocouple inserted into the myocardium. When cooling was initiated before a 30' CAO, temperature decreased 4-5(C resulting in a reduction of infarct size of 65% compared to normothermic hearts. Mild RMH was also protective when initiated after the start of ischemia. If begun 10' into a 30'-CAO, infarct size was reduced by 48%. Even when the duration of ischemia was increased to 180' and treatment delayed until 30' after occlusion, RMH resulted in a significant infarct size reduction compared with normothermic control hearts. RMH was not beneficial when begun just before reperfusion. The reduction in infarct size was not a result of differences in body temperature, ischemic risk area size, hemodynamics, nor regional myocardial blood flow, which were comparable among control and treated groups in all studies. Started before or after ischemia, RMH is an effective technique to protect the heart, reducing necrosis resulting from ischemia.

Back to the top.
Presentation Number SAhale0248
Keywords: rabbit heart, hypothermia, temperature, myocardium, infarct size