Distinct Temporal Pattern of the Prediction of Lumen Remodeling of Lower Extremity Vein Bypass Grafts by Initial Local Hemodynamics.

Abstract

We predicted human lower extremity vein bypass graft remodeling by hemodynamics. Computed tomography and duplex ultrasound scans of 55 patients were performed at 1week and 1, 6, and 12months post-implantation to obtain wall shear stress (WSS) and oscillatory shear index (OSI) at 1-mm intervals via computational fluid dynamics simulations. Graft remodeling was quantified by computed tomography-measured lumen diameter changes in the early (1week-1month), intermediate (1-6months), and late (6-12months) periods. Linear mixed-effect models were constructed to examine the overall relationship between remodeling and initial hemodynamics using the average data of all cross sections within the same graft. A significant association of graft remodeling with WSS (p < 0.001) and time (p = 0.001) was found; however, the effect size decreased with time (every 2.7 dyne/cm2 increase of WSS was associated with a 0.39, 0.35, 0.002mm diameter increase in the three periods, respectively). The association of remodeling with OSI was significant only in the intermediate period (every 0.1 increase of OSI was associated with a 0.25mm lumen diameter decrease, p = 0.004). Therefore, the association of graft lumen remodeling with local hemodynamics has a distinct temporal pattern; WSS and OSI are predictive of remodeling only in certain postoperative periods.