EFFICIENCY OF AN EXTERNAL SUPPORT TO REDUCE LIPID INFILTRATION INTO VENOUS GRAFTS - IN-VITRO EVALUATION

Excessive distension of venous grafts due to arterial pressure enhance s the convective water transport (filtration flow) through the vessel wall, and thus might affect the infiltration of macromolecules such as lipoproteins, In this paired experimental study, filtration velocitie s were measured at 100 mm Hg for canine jugular veins with or without external supports of expanded polytetrafluoroethylene (ePTFE) arterial prostheses. In addition, to assess the effect of filtration velocity on lipid infiltration or uptake, canine jugular veins were wrapped ove r half of their lengths with ePTFE arterial prostheses and perfused wi th dog serum containing H-3-cholesterol at a pressure of 100 mm Hg, At 100 mm Hg, the average filtration velocity of the wrapped jugular vei ns was 7.9 +/- 1.3 x 10(-6) cm/s whereas the average filtration veloci ty of the unwrapped veins was 27.3 +/- 2.7 x 10(-6) cm/s (p < 0.005). Moreover, the unwrapped veins had a significantly higher uptake rate o f labeled cholesterol than the wrapped veins (10.9 +/- 7.3 x 10(-4) cm /h and 5.0 +/- 1.6 x 10(-4) cm/h, respectively, p < 0.005). In conclus ion, under arterial pressure, Veins experience excessive distention, w hich leads to significant increases in both filtration flow and choles terol uptake. An external wrap or support of ePTFE material protects v eins from excessive distension and thus may prevent atherosclerosis in venous grafts by reducing cholesterol uptake.