Abstract 3249: Late Endothelial Function of Bilateral Internal Thoracic Arteries Used as a Y-graft Configuration

Abstract

The manner in which a blood vessel is harvested for use as a coronary graft may be important in maintaining a viable and functional endothelial lining. Internal thoracic arteries (ITA), when used as a Y-graft configuration are characterized by the connection of a pedicled left ITA with preserved innervation and lymphatics and of a free skeletonized right ITA. To determine whether endothelial function differs between left and right ITA segments in a Y-graft configuration, 11 patients were studied 3 years after surgery. The endothelial-dependent vasodilator substance P was selectively infused (1.4 up to 22.4 pmol/min in doubling dose increments) in the ostium of ITA Y-grafts. A maximal endothelium-independent vasodilatory response was obtained by intragraft infusion of 2 mg isosorbide dinitrate (ISDN). Biplane angiograms obtained at 3 minutes intervals using an automated contrast injection system with fixed pre-set volume and pressure parameters were analyzed off-line using a quantitative analysis system (CAAS, Pie Medical). A similar dose-dependent vasodilatory response to substance P was observed in the left and in the right ITA (figure ). No difference in maximal endothelium-dependent response to substance P (7.4±4.3% in left ITA and 8.1 ± 5.3% in right ITA) or in maximal endothelium-independent response to ISDN (12.2 ± 4.4% in left ITA and 10.6 ± 8.1% in right ITA) was observed. In conclusion, the endothelial function and the vasodilator reserve of the two branches of a Y-graft ITA configuration appear similar 3 years after bypass surgery. This suggests that the preservation of the ITA pedicle does not significantly affect basal vasomotor tone or long-term endothelial function.