ObjectivesLow patency rates of saphenous vein grafts remain a major predicament in surgical revascularization. We examined a novel expandable external support device designed to mitigate causative factors for early and late graft failure.MethodsFor this study, fourteen adult sheep underwent cardiac revascularization using two vein grafts for each; one to the LAD and the other to the obtuse marginal artery. One graft was supported with the device while the other served as a control. Target vessel was alternated between consecutive cases. The animals underwent immediate and late angiography and were then sacrificed for histopathologic evaluation.ResultsOf the fourteen animals studied, three died peri-operatively (unrelated to device implanted), and ten survived the follow-up period. Among surviving animals, three grafts were thrombosed and one was occluded, all in the control group (p = 0.043). Quantitative angiographic evaluation revealed no difference between groups in immediate level of graft uniformity, with a coefficient-of-variance (CV%) of 7.39 in control versus 5.07 in the supported grafts, p = 0.082. At 12 weeks, there was a significant non-uniformity in the control grafts versus the supported grafts (CV = 22.12 versus 3.01, p < 0.002). In histopathologic evaluation, mean intimal area of the supported grafts was significantly lower than in the control grafts (11.2 mm^2 versus 23.1 mm^2 p < 0.02).ConclusionsThe expandable SVG external support system was found to be efficacious in reducing SVG’s non-uniform dilatation and neointimal formation in an animal model early after CABG. This novel technology may have the potential to improve SVG patency rates after surgical myocardial revascularization.

IntroductionThe autologous vein bypass remains the most effective and durable revascularization strategy for patients with critical limb ischemia [1]. However, despite significant advances in the understanding of venous pathophysiology post-implantation, little progress was made in the clinical setting in which vein graft failure rate is still 30 -50% within 3 to 5 years [1,2].Early graft occlusion, within one month from implantation, is generally ascribed to technical or procedural related complications (e.g., kinking and twisting) or poor conduit quality. Late vein graft failure is attributed to the structural changes that occur in the conduit immediately post-implantation due to the exposure to 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). Inhibition of vein graft remodeling and neo-intimal formation using a cobalt chrome external support 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.