Endothelial injury and trapping of blood cells in human myocardium following coronary bypass surgery

To investigate the focal myocytic and microvascular injury that develops du ring the first hour of reperfusion after hypothermic cardioplegic cardiac a rrest, and to compare the influence of gentle versus more abrupt reperfusio n, serial atrial biopsies were obtained from 14 patients undergoing unevent ful coronary bypass surgery. The biopsies were taken before cardioplegia, a t the start of reperfusion, and after 20 and 60 min of reperfusion. Transmi ssion electron micrographs of biopsies examined by stereological techniques revealed endothelial injury. Following 20 min reperfusion there was accumu lation of both red blood cells (p = 0.03) and polymorphonuclear leucocytes (p = 0.0004) were found. There was also intravascular accumulation of plate lets (p = 0.008) and extravasation of red blood cells (p = 0.02), which inc reased throughout the observation period. If reperfusion was started with a gradual rise in temperature and pressure, the numbers of platelets in the microvessels were lower than following ordinary, abrupt reperfusion (p = 0. 06). It is concluded that reperfusion injury is associated with microcircul atory disturbances with trappings of blood cells, changes which may be favo urably modified by a gentle reperfusion technique.