Morphofunctional characteristics of the microcirculation and contractile myocardium during graded restriction of coronary blood flow.

In experiments on 50 adult mongrel dogs the morphofunctional changes were studied in the microcirculation vasculature and contractile myocardium during restriction of the blood flow through the circumflex branch of the left coronary artery by 30, 50, 70 and 90 per cent. The analyses were made with the application of various light optical methods and of electron microscopy. It was found that the morphological changes in the microcirculation vasculature and in the cardiomyocytes (CMC) were proportional to the degree of coronary insufficiency, were mutually connected, and included both pathological and compensatory alterations. The microhaemodynamic (MHD) disturbances had a mosaic character. In consequence of restricted transendothelial transport there developed interstitial oedema with accumulation of products of disturbed metabolism in the interstitial tissue. The hypoxia-induced disturbance of the coordination of CMC contractions and CMC lesions leading to the genesis of contractures and sarcoplasmic oedema may induce microvascular compression and thus further worsen the MHD disturbances.