CYCLIC PHENOMENA IN EARLY MYOCARDIAL-INFARCTION

It has been shown by a number of authors that early myocardial infarct ion constitutes a dynamic process of cyclic oscillation between corona ry occlusion and spontaneous coronary reopening. Infarct-markers, such as ST-segment elevation, serum-creatine kinase isoenzyme MB, the atri onatriuretic peptide (ANP) and serum-myoglobin (Mb) exhibit cyclic beh aviour pattern during early AMI and thus reflect episodes of intermitt ent, spontaneous reperfusion. The latter have recently been verified b y angiography. The mechanism underlying the phenomena seen in early my ocardial infarction is likely to be based on a constant vasoconstricti ve stimulus, deriving from aggregating platelets. The vasoconstriction subsequent to platelet aggregation produces an initial episode of myo cardial ischemia. This episode is followed by a hypoxia of the artery wall. Reactive coronary dilation secondary to ischemia is than promote d by the release of vasoactive by-products of anaerobic glycolysis as well as changes in the open propability of certain transmembrane ion c hannels. Thereafter, the initial coronary occlusion is interrupted by transient vasodilation. A wave of reperfusion follows and leads to reo xygenation and wash-out of ischemia-induced vasodilative components as well as biochemical markers. The vasoconstrictive forces then take ov er again. This results in repeated waves of reperfusion. A number of a rguments in favour of this concepts are discussed in this paper.