DIFFERENCES IN VASOREACTIVITY BETWEEN GASTROEPIPLOIC ARTERY GRAFTS LATE AFTER BYPASS-SURGERY AND GRAFTED CORONARY ARTERIES

Background The gastroepiploic artery is increasingly used as an altern ative arterial coronary bypass conduit. In vitro studies have reported differences in vasoreactivity among various types of coronary graft c onduits, susceptible to influencing the adaptation of myocardial blood flow and long-term patency rate. Methods and Results To evaluate in v ivo the vasoreactivity of gastroepiploic artery grafts implanted long- term, nine angiographically smooth grafts implanted to the distal righ t or to the left circumflex coronary artery were studied with quantita tive angiography 6 to 36 months after surgery. Angiograms were obtaine d on 35mm cinefilms in basal conditions, after injection of methylergo metrine (0.4 mg IV), and after intragraft injection of 1 mg isosorbide dinitrate. In basal conditions, there was no difference in luminal di ameter between gastroepiploic and coronary arteries (1.64+/-0.32 versu s 1.51+/-0.31 mm; P=NS). After methylergometrine, a constriction was o bserved in all gastroepiploic artery grafts (-14+/-6% of basal diamete r) and in all but one grafted coronary artery (-6+/-5%). After isosorb ide dinitrate, a dilation was consistently observed in all gastroepipl oic artery grafts (+26+/-9%) and grafted coronary arteries (+14+/-7% o f basal). Changes in lumen diameter in response to these constrictor a nd dilator stimuli, either expressed in absolute values or in percenta ge of control were significantly greater (P<.001) in gastroepiploic ar tery grafts than in grafted coronary arteries. Conclusions Gastroepipl oic artery grafts implanted long-term are more reactive than grafted c oronary arteries to ergometrine and nitrates. This response differs fr om that previously reported of internal mammary artery grafts to the s ame pharmacological vasoactive stimuli. This suggests that the concept of a more efficient endothelium-dependent control of vasomotor tone c ontributing to better long-term functional results of internal mammary artery grafts cannot be directly extrapolated to gastroepiploic arter y grafts.