Assessment of inhomogeneities in elastic properties of in situ and reversed saphenous vein grafts in humans

The elastic properties of newly implanted in situ (IS, n = 11) and reversed (RV, n = 21) saphenous grafts were studied with the use of Vessel Wall Doppler Tracking. From diameter, diameter change and simultaneously recorded pulse pressure, distensibility coefficient (DC) representing the intrinsic elastic properties and compliance coefficient (CC), a parameter of haemodynamic capacity, were calculated. In order to obtain a mechanical profile, the parameters were assessed at defined sites down the graft and native arterial system. In the RV group the reversal of the grafts resulted in a difference in diameter around the proximal anastomoses (7.4 vs. 4.3 mm, p < 0.01) and from proximal to distal (4.3 vs. 5.9 mm, p < 0.01) in the grafts; around the distal anastomoses no differences in diameter were observed. Due to the natural taper of the in situ grafts, diameter decreased from proximal to distal in the grafts (4.5 vs. 3.2 mm, p < 0.05) and no size differences were found around the anastomoses. In the RV group a decrease in DC was observed from proximal to distal in the grafts; whereas in the IS group no change in DC was found from proximal to distal in the grafts but a decrease in DC was observed around the distal anastomoses. In the RV group, a decrease in CC at the proximal anastomoses was observed (0.25 vs. 0.09 mm² /kPa, p < 0.01). In the IS group no change in CC was observed around the proximal anastomoses and distal anastomoses. However, a decrease of this parameter from proximal to distal in the grafts was found (0.07 vs. 0.04 mm² /kPa, p < 0.05). These results demonstrate that the elastic properties of newly inserted human saphenous vein grafts are comparable with native artery elastic properties. In contrast to the in situ technique, a mismatch in haemodynamic capacity is apparent round the proximal anastomoses using the reversed technique, indicating haemodynamic benefit at the proximal anastomoses of in situ grafts. An important decrease in haemodynamic capacity is present in in situ grafts, whereas this parameter remains stable in reversed grafts, suggesting intrinsic haemodynamic advantage in reversed grafts.