Early adaptation of human lower extremity vein grafts: Wall stiffness changes accompany geometric remodeling

Objective: To quantitatively describe the temporal changes in elastic properties and wall dimensions in lower-extremity vein grafts after implantation. Design of study: This is a prospective study of patients (N = 38) undergoing lower extremity bypass grafts (N = 41) with autologous veins. Pulse wave velocity (PWV), luminal diameter, and wall thickness measurements were obtained by duplex ultrasound scan intraoperatively and at 1, 3, and 6 months postoperatively for assessment of graft dimensions and wall stiffness. Results: Lower extremity vein grafts showed an increase in PWV (from 16 ± 1 to 21 ± 3 cm/s; mean ± SEM; P = .08), reflecting an increase in wall stiffness (from 1.2 ± 0.2 to 2.5 ± 0.7 × 10⁶ dynes/cm; P = .02) and wall thickness (from 0.47 ± 0.03 to 0.61 ± 0.004 mm; P = .04) over the first 6 months after implantation. Changes in lumen diameter were positively correlated with changes in external graft diameter (P < .01) and negatively correlated with initial lumen diameter (P < .01) but not with changes in the wall thickness. Conclusions: These results suggest complex remodeling of vein grafts during the first several months after implantation, with increased wall thickness occurring independent of variable changes in lumen diameter. Simultaneously, a marked increase in wall stiffness over this interval suggests a likely role for collagen deposition.