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To evaluate the effectiveness of retrograde cardioplegia and reperfusion, a total of 266 patients undergoing coronary bypass surgery between Nov 1987 to Dec 1989 were divided into three groups depending on the method of cardioplegic fluid delivery and reperfusion. In group I (80 patients) antegrade cardioplegia and reperfusion was used. In group II (98 patients) antegrade and retrograde cardioplegia and antegrade reperfusion was used while in group III antegrade and retrograde cardioplegia and retrograde reperfusion was used. Myocardial functions were studied with the help of an on-line computer on the basis of mathematical model of heart before and after cardiopulmonary bypass. Biopsy specimens were collected before, during and after cardiopulmonary bypass in order to study myocardial structural changes. In group I patients there was decrease in myocardial function in the immediate post perfusion period while group II patients had considerable improvement in their myocardial function and groups III patients showed further improvement in it. Ultrastructural myocardial study revealed considerable detrimental changes in group I, minimal changes in group II and no change in group III patients. Thus in our experience retrograde cardioplegia and retrograde reperfusion with warm oxygenated blood provide maximum myocardial protection in patients with multiple coronary artery lesions.

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Our studies have revealed a prognostically poor course in postinfarction angina pectoris patients on conservative medicamentous treatment. The mortality rate within the first year of this syndrome onset was 19.8 per cent among conservatively treated patients. Surgical management of these patients had a significantly better prognosis. Despite the fact that there was a great difference in survival rates between the studied groups at the hospital stage, the survival rate was significantly higher at subsequent stages in surgical patients compared to that in the conservatively treated group, and correlated with that in a larger population of matched age. In addition, surgical treatment was found to substantially improve the quality of life in patients with postinfarction angina pectoris which implies lowered frequency of attacks, increased exercise tolerance, and improved working capacity.

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The results of quantitative morphological macro-, micro-, and ultrastructural (myocardial biopsies) studies of the ventricles with perimembranous septal defect in 135 infants under the age of one year have been compared. In newborns there appeared ventricular myocardial hyperplasia and low absolute and relative values of all the myocardial parameters versus normal control. At the age of 3 months the parameters were similar to or above the control ones exceeding them considerably by the age of 10-12 months. The comparison of the parameters of the septal parts showed predominant abnormality of the sinus part indicating that the perimembranous ventricular septal defect entity is a sinus one.

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Four varieties of infectious endocarditis were identified after cardiac valve bioprostheses: early acute, early subacute, late acute, and late subacute forms. Any of these forms may be of bacterial, fungal, or mixed (bacterial and fungal) origin. In the early forms, the infection was of exogenous origin, with a predominance of Gram-positive organisms, whereas in the late forms it was endogenous with a preponderance of Gram-negative flora. The hallmarks of fungal thromboendocarditis were an early massive thrombosis of the bioprosthesis, multiple thromboembolism, and an absence of cellular reaction in the cuspal tissue. In the subacute bacterial endocarditis, progressive dysfunction of the bioprosthesis resulting from calcination of bacteria-containing cusps and thrombi was noted.

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Results of an experiment on the preservation of bioprostheses prepared from porcine aortal valves are presented. It is described how the structure of the cusps is affected by autolytic processes, by exposure to various concentrations of glutaraldehyde, and by sequential exposure to glutaraldehyde and papain solutions. Xenogeneic aortal complexes must be processed within the first 24 hours after collection since later on they undergo autolysis whereby the fibroblasts are destroyed and collagen fibrils become damaged. Low glutaraldehyde concentrations preserve the structure of these well enough, although concentrations below 0.5% were found to make the ground substance edematous and cause structural damage to the fibroblasts. Papain treatment without glutaraldehyde pretreatment leads to profound changes in the fibrous structures and in the cells, whereas glutaraldehyde fixation followed by papain treatment assures adequate preservation.

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During surgical correction of Fallot's tetrad the authors discovered the decrease of macroergic phosphate concentration and moderately marked signs of cardiomyocytic ultrastructural changes, such as mitochondrial injuries, decrease of glycogen levels, insignificant intracellular edema, no increase of membrane penetration. Changes of endothelial cells were absent. In children not over 1 year old under myocardial protection with hypothermic perfusion (at low volume rates) some decrease of macroergic phosphates occurred, as well as a moderate decrease of the mitochondrial index, glycogen content decrease, there was no intracellular edema. The discovered structural changes are minimal and reversible. A close correlation was found between the electron microscopic data and the character of myocardial energetic metabolism, the biochemical changes preceding the ultrastructural ones. Comparison of morpho- and biochemical changes in the myocardium of the majority of patients with impaired myocardial function confirmed the existence of a complex relationship between them.

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The work presents data on the relief of the endothelial surface of initial portions of the common carotid artery and the common iliac artery of adult man obtained by the method of scanning electron microscopy. In middle-aged humans this relief has all the characteristic features which were noted in studying the aorta. Considerable changes of the endothelial surface relief were shown in elderly and old people in connection with the development of atherosclerosis. Postmortem alterations can result in sharp distortion of the endothelial surface relief.

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The spatial interrelationships of osteon canals were studied in corrosion preparations with the help of rastral electron microscopy. The structure of microvessels, their belonging to a definite link of the microcirculatory bed, the interaction of vessels and their position with respect to the osseous matrix were studied in bone sections impregnated with silver nitrate after V. V. Kuprijanov. Haversian canals in the compact substance of the bone are longitudinally oriented, can duplicate and form a single system of canals. The neighbouring canals of osteons might be bound by means of Volkmann's canals. The investigation of the Haversian canals in serial sections has shown that the diameter of the same canals of osteons can change at different levels, the diameter of the osteons themselves remaining unchanged. This seems to speak of uneven development of osteons in their different parts. In the Haversian canal there are one-two or occasionally three vessels having all three links of the morphocirculatory bed. The course and ramification of the vessel are identical to the shape of the osteon canal which includes them. The vessels are closely connected with the bony matrix by means of connective tissue bundles directed from the canal wall to the vessel wall. These bundles appear to serve as a peculiar anchor or amortizing apparatus and its elasticity might be a factor of a change of the shape and direction of the canal vessels in the bone development process.

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The structure of osseous laminas of osteons was studied by methods of translucent and rastral electron microscopy. All laminas were shown to consist of collagenous fibrils and crystals of hydroxyapatite. The collagenous fibrils in the lamina are united into interwining bundles. The adjacent osseous laminas are different in orientation of fibrils and bundles in relation to the axis of the Haversian canal. The laminas are bound by bundles and solitary fibrils passing from one lamina into the other. In decalcificated sections of laminas of osteons have different relief. The laminas with longitudinally disposed fibrils project over the laminas with transversely disposed fibrils.

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