Inhibition of vein graft remodeling and neo-intimal formation using a cobalt chrome external support

Objective: Despite significant advances in the understanding of vein graft remodeling during the post-implantation, vein graft disease is still a major limitation of surgical revascularization. The study objective was to evaluate the performance of a new cobalt chrome external support device designed to mitigate vein graft remodeling and development of intimal hyperplasia. Methods: Bilateral carotid interposition of reversed saphenous vein graft segments was performed in seven‏ adult sheep. Following completion of the first anastomosis, randomization was performed to allocate the experimental and control grafts in each animal. Post-procedure, Doppler US was used to assess grafts lumen diameter at T0 and then 3-5 and 12-14 weeks after surgery. At 12-14 weeks, all sheep underwent angiography to assess grafts patency and lumen uniformity (coefficient of variance - CV) after which they were sacrificed, and all grafts were harvested for microscopic histological analysis. Results: Baseline (T0) internal diameter was not significantly different between the supported and unsupported grafts. At twelve to fourteen weeks, the internal diameter of supported grafts remained unchanged and was significantly lower compared to the non-supported grafts (6.6mm±0.4mm vs. 12.8mm±4.0mm respectively, p= 0.0001). Percentage coefficient of variance (%CV) was 4.6%±4.3 in the supported grafts as opposed to average CV% of 14.7%±6.5 in the non-stented group (p=0.011). Neointimal area was significantly lower in the stented compared to the non-stented group (1.4 mm2±3.3mm2 versus 9.6mm2±9.7mm2 respectively, p=0.009). Conclusions: External support of vein grafts using a braided cobalt chrome external stent reduces early vein graft remodeling and mitigates the development of neointimal hyperplasia.