Structural basis of myocardial stunning after coronary artery bypass surgery

Acute heart failure is the main cause of death in early postoperative period after coronary artery bypass surgery but mechanism of its development remains poorly understood. Morphological study of myocardium of patients who died during first 2 days after surgery revealed diffuse changes of cardiomyocytes consisting of contractural alterations and intracellular insoluble deposits of calcium phosphate. Pronounced disturbances of microcirculation appearing as foci of extravasated blood and stasis of leukocytes were also present. Meanwhile no cellular or enzymatic reactions indicative of foci of local ischemia were found. The observed morphological changes are supposed to constitute structural basis of stunning of ischemic myocardium during restoration of coronary blood flow. These structural changes are presumably caused by disturbed calcium ion transport and abundance of various metabolites in the reperfused zone.