Design of a Corrugated Vascular Graft with Enhanced Compliance and Kink Resistance

Abstract

The development of a small-diameter vascular graft for coronary artery bypass grafting necessitates a balance of key biomechanical properties to prevent failure. Prior iterative design of a multilayer vascular graft achieved arterial compliance-matching to prevent failure due to intimal hyperplasia while retaining sufficient burst pressure and suture retention strength. Although promising, graft kinking prevented long-term evaluation in vivo. To enhance kink resistance, a post-electrospinning molding method was developed to impart a corrugated geometry. Corrugations enhance kink resistance during bending through expansion and folding of the pleats to prevent ovalization and subsequent buckling. The corrugated graft significantly improved kink resistance with kink radii similar to synthetic grafts used in the clinic. In contrast to prior literature, the corrugated grafts displayed compliance values in the range of arterial values (10.4%/mmHg × 10⁻² ± 0.3%/mmHg × 10⁻²) for improved graft-artery compliance-matching. A finite element (FE) model of compliance was used to elucidate the effect of corrugated geometry on graft compliance. The FE-predicted compliance values agreed well with experimental results and demonstrated an increase in Lagrange strain magnitude of the corrugated valleys that was correlated with a higher luminal compliance. To ensure clinical utility of corrugated grafts, candidate grafts were tested for suture retention strength, burst pressure, and stability under physiological loading. The corrugated graft retained biomechanical properties above or similar to reported values of the saphenous vein, demonstrating suitability for implantation. Finally, no significant change in graft dimensions demonstrated stability of the post-fabrication corrugation geometry after 30 days under pulsatile flow. A small-diameter vascular graft with this unique combination of biomechanical properties has the potential to improve long-term outcomes in coronary artery bypass graft procedures.