Long-term (5 to 12 years) serial studies of internal mammary artery and saphenous vein coronary bypass grafts.

Comparative anatomic studies of various arterial conduits for myocardial revascularization.

Twelve-year experience with internal mammary artery for coronary artery bypass.

Endothelin-1 is a 21-amino acid endothelial vasoconstrictor peptide that may be the physiological antagonist of endothelium-derived relaxing factor (EDRF). Endothelin-1 (10(-11)-3 x 10(-7) M) evoked potent contractions of isolated internal mammary arteries, internal mammary veins, and saphenous veins, which were enhanced in internal mammary veins as compared with internal mammary arteries (concentration shift, 6.3-fold; p less than 0.05) but not in the saphenous veins. Endothelial removal augmented the response to the peptide (at 3 x 10(-7) M) in internal mammary arteries (p less than 0.05) but not in veins. In the artery, EDRF released by acetylcholine or bradykinin reversed endothelin-1-induced contractions; in saphenous veins, both agonists were much less effective compared with the artery and veins contracted with norepinephrine (p less than 0.005-0.01). This inhibition of endothelium-dependent relaxations in veins occurred at half-maximal contractions but was most prominent at maximal contractions to the peptide. Nitric oxide similarly inhibited contractions to endothelin-1 and norepinephrine in internal mammary arteries, whereas in veins that were contracted with endothelin-1 but not with norepinephrine, the relaxations were blunted (p less than 0.005). The nitric oxide donor SIN-1 and sodium nitroprusside induced complete relaxations of internal mammary arteries but were less effective in veins contracted with endothelin-1 (p less than 0.005). Thus, in normal human arteries, EDRF inhibits endothelin-1-induced contractions, whereas the peptide specifically attenuates the effects of EDRF and nitrovasodilators in veins. This may be important in pathological conditions associated with increased levels of endothelin-1 and in veins used as coronary bypass grafts.

Interaction between endothelin-1 and endothelium-derived relaxing factor in human arteries and veins.

Single versus bilateral internal mammary artery grafts: 10-year outcome analysis

Two hundred ninety-eight patients who received internal mammary artery (IMA) grafts were reviewed seven to nine years after surgery; 91.6% of these patients are still alive. In 29.5% of these patients there was postoperative graft visualization, and 90% of the studies were performed because of suspected graft failure. Attrition of the IMA graft was minimal. At zero to 24 months after surgery, 93.4% of grafts were patent. At 60 to 108 months 94.4% were patent and there was little, if any, evidence of atherosclerosis in the IMAs. Precise technique in preparation and anastomosis of the IMA is essential for long-term patency. For bypassing obstructive lesions, we recommend selection of the IMA (if it has sufficient size and flow) for use in the left anterior descending, large diagonal, or marginal vessel in the left coronary artery circulation. ( JAMA 1981;246:2181-2183)

Gilbert Johnson

Papers

The internal mammary artery graft. Its longevity after coronary bypass