The daunting quest for a small diameter vascular graft

Abstract

Due to inadequate vascular perfusion broughtabout by vascular disease or trauma, there is asignificant worldwide demand for a smalldiameter (<5 mm inner diameter [ID]) vas-cular graft for use as a bypass or replacementconduit. As a surgeon, it is preferable to useautologous vascular material (i.e., veins orarteries) for arterial bypass surgery, since theyshow, by far, the lowest failure rates. How-ever, the use of autologous tissue is hamperedby limited availability and suitability due toextensive peripheral vascular disease and/oruse in a previous bypass surgery. Today’sclinically-used synthetic vascular graft materi-als, when utilized as small diameter substitutes,are associated with high-occlusion/failurerates. Thus, it is imperative to develop innova-tive technologies targeted to the fabrication ofa small diameter vascular graft.Since there is currently no clinically accept-able nonautologous, small diameter vasculargraft, perhaps one of the innovative technolo-gies currently being evaluated may somedayrevolutionize the field of vascular surgery.The innovative technologies utilized in thedevelopment or improvement of small dia-meter vascular grafts can be classified into thefollowing groups, with each presenting a hostof concerns, limitations and/or design issues:• Biostable, synthetic vascular grafts• Synthetic vascular grafts – active coatings ordrug elution• Endothelial cell seeding/sodding• Bioresorbable vascular grafts• Tissue engineered vascular graftsIn general, the ideal vascular graft wouldhave the following characteristics: • Ease of surgical handling• Suture retention• Flexibility with kink resistance• Biocompatibility (nontoxic and non-thrombogenic)• Postimplantation durability after tissueingrowth• Infection resistance• Leak resistance, but with adequate porosityfor healing/regeneration • Appropriate remodeling response• Compliance matching that of the nativeartery• Resistance to aneurysm formationOther concerns with the ideal vascular graftare that it must be easily manufactured,sterilized and stored, available in a variety ofsizes (lengths, diameters and tapers) andeconomical. Basically, surgeons are demand-ing the off-the-shelf availability of currentsynthetic grafts without the short- and long-term complications. Fulfilling these require-ments creates a daunting challenge in thedevelopment of a vascular graft worthy ofclinical acceptance.The use of a biostable, polymeric vasculargraft was first published in 1952 by Voorheesand colleagues who presented the concept ofa synthetic conduit as a replacement fordeficient natural blood vessels