Echocardiographic features of congenital mitral stenosis

The effects of 1 hour of occlusion of the left anterior descending coronary artery and subsequent reperfusion were studied for 3 hours in anesthetized closed chest pigs using an intracoronary balloon occluding technique. In 12 pigs subjected to reperfusion, S-T segment elevation decreased to control levels within 30 minutes and was significantly less than in 10 control pigs without reperfusion (P < 0.05). R wave amplitude was unaffected by the reperfusion. The more rapid fall of S-T segments in the reperfused group was accompanied by major hemorrhage in all reperfused hearts; hemorrhage occurred in only one control heart. The extent of hemorrhage was quantified and was significantly greater in the reperfused than in the control group (P < 0.01). Hemorrhage after reperfusion was unaffected by mannitol-induced increase in serum osmolallty but was greatly decreased by limitation of the occlusion period to 15 minutes. Myocardial wall motion was quantified angiographljcally. Shortening fraction of the area of the left ventricle most severely affected by occlusion decreased to similar levels in both groups. After reperfusion it remained similar in both groups at three hours. Adjacent left ventricular areas were likewise unaffected by reperfusion.This study thus documents the occurrence of postreperfusion myocardial hemorrhage in an animal with a coronary circulation similar to man's. Hemorrhage is directly related to the duration of occlusion but appears to be unaffected by mannitol given before reperfusion. Caution is advised both during bypass surgery, in which occlusion and reperfusion occur, and In efforts to restore coronary blood flow during acute myocardial infarction.