Comparative reactivity and mechanical properties of human isolated internal mammary and radial arteries

The response of isolated blood vessels to a variety of vasoactive agonists is modulated by the presence of endothelial cells. Indeed, these cells can release both dilator and constrictor substances. The major endothelium-derived relaxing factor may be nitric oxide, which activates soluble guanylate cyclase in the smooth muscle, although the endothelial cells also secrete an unidentified hyperpolarizing factor. Among the natural stimuli for the release of endothelium-derived relaxing factors are circulating hormones, platelet products, thrombin, shear stress, and certain autacoids. Endothelium-derived relaxing factors may contribute to the regulation of the release of atrial natriuretic factor and renin. The endothelial cells can also release constricting factors; among the likely candidates are superoxide anions or the peptide endothelin. In hypertensive blood vessels, the ability to release endothelium-derived relaxing factors but not endothelium-derived contracting factors is blunted.

Eighteen years after its first introduction for coronary artery revascularization, the radial artery (RA) was reinvestigated because of unexpected good long-term results in the early series. Since July 1989, 104 patients underwent myocardial revascularization using 122 RA grafts (18 patients received two grafts). The left internal mammary artery (IMA) was concomitantly used as a pedicled graft in 100 cases and the right IMA in 19 cases; a free IMA graft was used in 29 cases and a saphenous vein graft in 24 cases. A mean of 2.8 grafts per patient were performed. Nine patients underwent associated procedures: carotid endarterectomy (3), aortic valve replacement (3), Bigelow procedure (1), and mitral valve repair (2). The target artery receiving the RA was the circumflex (n = 59), diagonal (n = 29), right coronary (n = 27), and left anterior descending (n = 7). One patient died (0.96%) and 2 had perioperative myocardial infarct. Sternal wound infection was noted in 3 cases of double IMA implantation. No ischemia of the hand was observed. All patients received diltiazem started intraoperatively and continued after discharge. In addition aspirin (100 mg/day) was given at discharge. Early angiographic controls (less than 2 weeks) were obtained in the first 50 consecutive patients and revealed 56 of 56 patent RA grafts, 48 of 48 patent left IMA grafts, 11 of 11 patent right IMA grafts, 14 of 18 patent free IMA grafts, and 8 of 9 patent vein grafts.(ABSTRACT TRUNCATED AT 250 WORDS)