Functional assessment of disease-free saphenous vein grafts at redo coronary artery bypass grafting

Background. Reoperations for coronary artery bypass grafting are on the ris e. The general rule of replacing all saphenous vein grafts (SVGs) older tha n 5 years of age at the time of reoperation has recently been challenged on clinical grounds. This study provides functional data of endothelial behav ior in long-term vein grafts. Methods. Previously plated SVGs were removed at the time of redo operations . Nitric oxide (NO) measurements in real time were carried out before and a fter stimulation with morphine. The measurements were compared to the angio graphic appearance of the grafts obtained prior to operation. Crafts were c ategorized into 3 groups: disease free, moderately diseased, and severely d iseased. Results. Sixteen grafts were analyzed. Five were angiographically disease-f ree, 4 had moderate, and 7 severe disease. In the disease-free group, peak NO production after 10(-6) mol/L morphine stimulation was 35 mol/L, equival ent to the production of native saphenous vein. The severely diseased group did not demonstrate an increase in NO production, and the moderately disea sed group produced a small rise in production. Conclusions. Measurement of NO release of old SVGs, when angiographically p ristine, equals that of native saphenous vein. These findings support the r ecent clinical observations that long-term angiographically disease-free ve in grafts are biologically privileged. (C) 2000 by The Society of Thoracic Surgeons.