Adaptive changes in autogenous vein grafts for arterial reconstruction: Clinical implications

A, While the mean bypass graft lumen increases about 22% over the first 6 months following implantation. B, Considerable variability exists between individual grafts. C, Early luminal remodeling is correlated with initial shear stress at the time of implantation. D, Temporally distinct from luminal remodeling, the vein graft significantly stiffens between 1 and 3 months following implantation. Adapted from Reference 10.

Vein graft lumen change (percent) from implantation to 1 month in a population undergoing lower extremity bypass grafting for arterial occlusive disease. Luminal measurements were made with high resolution M-mode ultrasound at the same location of the vein graft for the operative and the 1 month assessment. By dichotomizing the population by baseline plasma CRP levels above and below 5 mg/L, disparate early luminal remodeling patterns of the vein graft become apparent, 37% vs 10%, P = .0072. Thus, patients with high levels of systemic inflammation have impaired ability to positively remodel vein grafts, adapted from Reference 93.

Modes of vein graft failure. While the majority of intimal hyperplasia in vein grafts is focal, a substantial minority (12%) is diffuse. A, Represents a 6-month-old vein graft in a 67-year-old white man that developed a midgraft stenosis (arrow) that was successfully treated with a vein patch angioplasty. B, Represents a 4-month-old vein graft in a 77-year-old black women undergoing angiography for contralateral limb ischemia. C, Three months later, she developed diffuse intimal hyperplasia which progressed to vein graft occlusion.

Histologic sections (×10) of an 8-month-old vein graft which developed a focal midgraft stenosis and underwent open revision with a short interposition graft. The vein was of uniform size and caliber at the time of implantation. A, The sections were taken approximately 2 cm from one another. The area of stenosis has developed marked intimal hyperplasia and has a smaller area circumscribed by the internal elastic laminae as well as decreased total vessel diameter indicative of negative remodeling of the entire vein graft. B, Theoretical normal and abnormal adaptation patterns of a human lower extremity vein grafts. Normally the lumen and wall area increase in the early postimplantation period to produce a lumen diameter to wall thickness ratio of about 7.

Flow mediated vasodilation in mature human saphenous vein grafts demonstrates a functional endothelium. A, Application of an occlusive blood pressure cuff (220 mm Hg) to the proximal calf of a cohort of patients undergoing femoro-popliteal bypass grafts for 5 minutes produces an increase in blood flow and shear stress within the graft. B, In this cohort, flow mediated, endothelium dependent vasodilation was 5.3% and nitroglycerin mediated, endothelium independent (0.4 mg sublingual nitroglycerin) dilation was 3.7%.