THE FACTORS INFLUENCING EARLY PATENCY OF CORONARY-ARTERY BYPASS VEIN GRAFTS - CORRELATION OF ANGIOGRAPHIC AND ULTRASTRUCTURAL FINDINGS

Abstract

To test the hypothesis that suboptimal preparation of saphenous veins may adversely affect early patency of aorta-coronary artery bypass grafts, a nonrandomized prospective study was undertaken comparing 2 methods of saphenous vein preparation prior to grafting. Forty recatheterizations were performed during the postoperative hospital stay (approximately 10 days) in 2 groups of asymptomatic patients who had undergone isolated coronary artery bypass grafting. Veins from patients in Group I were bathed in autologous, heparinized blood at 20.degree. C and distended to 80 mm Hg, prior to grafting. The veins from Group II patients were prepared in an identical manner, except that the bathing solution consisted of heparinized electrolyte solution with added papaverine (0.6 mg/ml). Segments of vein from each group were obtained prior to grafting and preserved in 3% glutaraldehyde for subsequent EM studies. Operative technique in both groups of patients was identical and all procedures were performed by the same surgeons. Comparison of patients in Groups I and II revealed no significant difference in the number of diseased vessels per patient (3.1 vs. 3.4), number of grafts per patient (2.9 vs. 2.9), native vessel diameter (1.9 vs. 1.7 mm), and postoperative graft flows (65 vs. 68 cm3/min). Early postoperative graft patency in Group II patients was 93% vs. 80% in patients in Group I (P < 0.01). EM analysis revealed severe spasm of venous smooth muscle in the blood-stored veins causing intraluminal smooth muscle cell cytoplasmic protrusions with resultant endothelial separation and desquamation. Formation of fibrin-platelet microaggregates was common. These findings were not present in the solution-treated veins. In view of these ultrastructural findings, and the highly significant difference in patency rates, all blood storage techniques are abandoned saphenous veins are now prepared by soaking them in a clear bathing medium with added heparin and papaverine. Long-term follow-up of these patients is currently in progress and may reveal even more dramatic results than were already observed.