Evaluation of a novel compliance-matching aortic graft in a swine model

Abstract

The mismatch of elastic properties between the arterial tissue and the vascular grafts, commonly called compliance mismatch, is responsible for many deleterious post-operative complications. Currently, there is an absence of prostheses that conform with the compliance of healthy aortas. We aimed to evaluate the in vivo performance of novel compliance-matching grafts in a swine model and compare it to the native aorta and to gold-standard aortic grafts.We proposed a compliance-matching graft design, composed of a standard aortic graft surrounded by an optimized Nickel-Titanium compliance-augmenting layer. We replaced the thoracic aorta of six domestic pigs with compliance-matching grafts under cardiopulmonary bypass. We removed the compliance-regulating layer of the compliant grafts, so that gold-standard grafts remained implanted. The aortic pressure and flow rate were measured at the three stages of the experiment to assess hypertension and arterial stiffness. The compliance-matching grafts were implanted without inducing post-operative hypertension by maintaining systolic pressure (p = 0.26), aortic pulse wave velocity (p = 0.89) and aortic distensibility (p = 0.67) at healthy levels. The gold-standard grafts caused a significant rise in systolic pressure (p = 0.005), pulse wave velocity (p = 0.012) and they approximately doubled pulse pressure (p < 0.001). Our novel compliant grafts could diminish the complications caused by compliance-mismatch and they could surpass the clinical performance of existing prostheses. The proposed grafts comprise a step towards optimized treatment and improved life expectancy of patients subjected to aortic replacement.