Myocardial stunning. Morphological studies in acute experimental ischemia and intraoperatory myocardial biopsies.

Myocardial stunning represent a consequence of brief ischemia with reversible regional contractile dysfunction dependent persist from minute to days after reperfusion, despite the absence of irreversible damage and restoration of coronary blood flow. The evolution of these new ischemic entity were described by experimental acute ischemia and repeated intraoperatory myocardial biopsies effectuated near 200 patients with heart disease, excluding those with cardiac failure and atrial fibrillation. Using histological histoenzymological and particularly ultrastructural methods, only reversible mitochondrial and sarcoplasmatic reticulum lesions, slight glycogen granules depletions and sporadical dissociation of myofilaments by edema were seen. Major mechanism for the state was suggested: generation of oxygen derived free radicals with consequent oxidative stress and impaired calcium homeostasis. Rare morphological appearance on stunned myocardium was signaled in the references, our collective first made these studies in Romania.