Endothelium-dependent acetylcholine-induced vasodilatory response of saphenous vein grafts

It has been suggested that endothelial dysfunction is critical to saphenous vein graft (SVG) occlusion.

To evaluate in vivo endothelium-mediated vasoreactivity in angiographically non-stenotic SVG.

The group consisted of 31 patients (pts), aged 58.7+/-8.7 years, 54+/-38 months after coronary bypass surgery. In each patient one angiographically normal SVG was selected for the study. Endothelium-dependent vasoreactivity was investigated with acetylcholine (Ach) 50 microg intragraft infusion. Graft diameter changes were measured by quantitative computer angiography (QCA).

In 17 (54.8%) pts there was a significant reduction in graft diameter following Ach infusion, from 3.8+/-0.7 to 3.2+/-0.7 mm (p=0.0001), whereas in 4 (12.9%) pts there were no diameter changes (3.2+/-0.7 mm). In the 10 remaining pts (32.3%) we found graft dilatation from 3.5+/-0.5 mm to 3.9+/-0.5 mm (p=0.0002). In multivariate linear regression analysis, SVG dilatation positively correlated with a low ratio of graft/artery diameter (p <0.002), high HDL-cholesterol level (p <0.001) and absence of hypertension (p <0.03), and negatively correlated with postoperative myocardial infarction (p <0.01).

Endothelium-dependent vasodilatory response to Ach is present in one third of old SVG. Dilative response to Ach 50 is better preserved in SVG with smaller difference between graft/grafted artery diameters. Adequate matching of the graft/grafted artery diameters probably preserves the endothelium-dependent dilative response of the graft.