Histology of the postischaemic myocardium and its relation to left ventricular function.

The relation between the histology of the myocardium and left ventricular function was studied in 23 dogs submitted to 90 min of coronary artery occlusion followed by reperfusion for up to 1 week. It was shown that 32% of the perfusion area of the occluded coronary artery was irreversibly damaged. There was, however, no significant correlation between the decrease in left ventricular function (ejection fraction assessed by angiography) and the extent of myocardial necrosis. Upon reperfusion, salvage of 68% of the perfusion area of the occluded vessel was obtained. Viability of the myocardium in this area was demonstrated by electron microscopy. However, postischaemic regional function was completely lost in the first 24 h, in spite of this considerable amount of viable tissue. Nevertheless, regional function recovered after 1 week of reperfusion, which suggests a stunned myocardium in the early postischaemic phase. These results show that histological examination of postischaemic tissue has prognostic value in terms of recovery of function, but a direct correlation between structure and function does not exist in the early reperfusion phase.