Effect of moderate pressure distention on the human saphenous vein vasomotor function

Abstract

Background Manual pressure distension, which is commonly applied to the human saphenous vein graft for coronary artery bypass, is believed to have detrimental consequences for the graft patency. The vasomotor function of the vein after distention during surgical preparation for grafting and after distention in laboratory conditions at pressure of 50 to 600 mm Hg was studied. The effect of a combination of vasodilative agents to prevent vasospasm was also tested. Methods The contractile and dilatory responses of distended and undistended human saphenous veins and those after drug treatment were examined in organ baths under isometric conditions. Results Distention at the pressure range 100 to 300 mm Hg resulted in an increased contractile response of the saphenous vein to both α-adrenergic activation with 50 μmol/L phenylephrine (153.73% ± 15.69%) and depolarization with 80 mmol/L K + (141.03% ± 15.13%) in comparison with the undistended vein and did not impair the relaxation. In contrast manual distention during surgical preparation abolished the contractile response and impaired the relaxation. The application of a combination of vasodilative drugs (α-adrenergic antagonist phenoxybenzamine, 10 μmol/L, Rho-kinase inhibitor HA-1077, 50 μmol/L, and calcium blocker nicardipine, 1 μmol/L) eliminated the contractile response of the vein to phenylephrine and 80 mmol/L K +. This effect was sustained more than 20 hours after the washout of the drugs. Conclusions The distention of the human saphenous vein at moderate pressure combined with the application of the effective combination of vasodilative drugs before grafting into the arterial circulation could be a beneficial alternative to the current practice of uncontrolled pressure distension.