Potential role of velocity and wall tension in vein graft failure.

The factors contributing to early thrombosis or late intimal proliferation in arterialized vein grafts were studied in seven dogs. Autologous jugular veins replaced a segment of the cervical carotid artery bilaterally. Thirty minutes after graft installation and six months later, graft and proximal artery diameter, arterial pressure and blood flow were measured and wall tension, vascular resistance, flow velocity and energy loss between proximal artery and graft were computed. The diameter ratio of proximal artery to graft increased by 37% (p less than 0.05). Velocity of flow within the graft averaged 87% less than that in the proximal artery (p less than 0.05) and decreased by 58% after six months (p less than 0.05). Graft wall tension at both experimental periods was significantly higher than that of the proximal artery (p less than 0.05), increasing over six months by 91% (p less than 0.05). These results support contentions that low flow velocity contributes to early thrombosis of the graft and, that increased wall tension is significant factor in the pathogenesis of intimal thickening.