Effect of stent-graft length and compliance on aortic hemodynamics in a bench-top physiological flow circuit.

The aortic elasticity plays a vital role in buffering pulsatile blood flow, propelling blood to distal organs and the heart, and reducing cardiac workload. Aortic repair with a stent-graft can reduce this elasticity and hinder the aorta's ability to effectively perform its function. Conventional stent-grafts are associated with increased arterial stiffness, elevated pulse wave velocity (PWV), and adverse hemodynamic changes. This is largely driven by stiffness mismatch between the stent-graft and the native aortic wall, which alters mechanical compliance and hemodynamic response. This study evaluates a novel compliant nanofiber stent-graft (NF-SG) developed to closely mimic native aortic mechanics. Using a bench-top physiological flow circuit, we assessed the hemodynamic impacts of stent-graft stiffness and length on arterial parameters, including PWV, pulse pressure (PP), and distensibility in vitro, and compared these effects with conventional stent-grafts. Stent-graft stiffness significantly affected PWV, PP, and distensibility. Conventional stent-grafts showed 14 %-52 % increase in PWV depending on stent-graft length (p < 0.001), 5 %-32 % increase in PP, and 82 % reduction in mid-graft distensibility. In contrast, NF-SGs maintained PWV and PP near baseline levels with marginal effect of the stent-graft length. Distensibility in the mid-graft was reduced by 13 %-20 %, depending on the stent-graft length. The NF-SG's superior compliance and reduced hemodynamic perturbation were attributed to its mechanically optimized fabric and skeleton design. These findings underscore the clinical potential of the compliant stent-grafts to significantly mitigate long-term cardiovascular complications and preserve aortic functionality post-intervention.