Influence of ischemia before vein grafting on early hyperplasia of the graft and the dynamic changes of the intima after grafting
The effect of profound (4 degrees C) and moderate cooling (20 degrees C) on the endothelium of human saphenous vein grafts for aortocoronary bypass was studied. When harvesting the vein, a piece (5-6 cm) was taken for the study and divided in two equal parts. The segments were incubated in cell culture medium for 45 minutes at 4 degrees C and 20 degrees C respectively. They were then perfused with cell culture medium at a flow rate of 100 ml/min, with a pressure of 85 mmHg and a temperature of 20 degrees C. After termination of perfusion the percentage of luminal surface without endothelial cells was determined by morphometry with scanning electron microscopy. The veins that were exposed to 4 degrees C had a significantly higher degree of endothelial cell detachment than those exposed to 20 degrees C (p less than 0.003). This study indicates that cooling to 4 degrees C may be harmful to the endothelial lining of veins which are prepared for grafting into the arterial system. Such cooling should therefore probably be avoided.