MYOCARDIAL AND MICROVASCULAR INJURY FOLLOWING CORONARY SURGERY AND ITS ATTENUATION BY MODE OF REPERFUSION

In 14 patients undergoing coronary surgery, repeated atrial biopsies w ere obtained before and at the end of ischemia, and at 20 and 60 min o f reperfusion. In half of the patients reperfusion was initiated with an abrupt rise in blood temperature and pressure, in the other half wi th a gradual rise. The biopsies were prepared for transmission electro n microscopy and analyzed by stereological technique. In all biopsies, myocytic injury, as revealed by mitochondrial changes and intracellul ar edema, occurred following ischemia (P=0.0003 and 0.007, respectivel y). The intracellular edema regressed following 20 min of reperfusion (P=0.008). The myocytic mitochondrial changes persisted during reperfu sion towards the end of the observation period (P=0.0001). Interstitia l edema increased following ischemia (P=0.007) and persisted following 60 min of reperfusion (P=0.009). The capillary part was significantly reduced after 20 min of reperfusion (P=0.003), probably reflecting in terstitial edema. Most changes were reversible in nature, although foc i of irreversible changes were shown. In patients with a gradual start of reperfusion there was a significant regression of interstitial ede ma (P=0.005) at 60 min reperfusion compared to the patients with an ab rupt start, where the same changes seemed to persist or even increase. The study demonstrates that ''reperfusion injury'' occurs in human my ocardium. It can be discerned from ''ischemic'' injury, and it may be reduced by a gentle mode of reperfusion.