Ultrastuctural features of coronary microvessel endothelium when repairing congenital heart disease in infants and 1 to 3 year-old children

While repairing a congenital heart disease in children under 3 years old in the conditions of cardiopulmonary bypass and moderate hypothermia (33-34 °C) and protecting the myocardium with «Custodiol» solution, we carried out an ultrastructural analysis of intraoperative dynamics of various morphological types of endothelial cells in the microvessels of the coronary bed. It was found out that cardiosurgical stress in both infants and 1 to 3-year old children leads to injury of endothelium similar to colliquative necrosis and does not activate coagulation necrosis. The fact that «Custodiol» cardioplegic solution provides adequate protection of the main stage of surgery is verified by the absence of significant changes in the population part of dark endothelial cells in both groups of children. A labile ultrastructural response of the main-type cells and light ones, the quantitative dynamics of which in infants and older children is also of a unidirectional nature, suggests that coronary endothelium in patients at an early age has a somewhat lowered reserve to adapt to cardiosurgical stress.