Effect of transcatheter aortic valve materials on thrombogenesis
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Transcatheter aortic valve replacement (TAVR) is a minimally invasive technique introduced to treat patients with aortic stenosis who are at high surgical risk. Despite its advantages over the traditional open-heart surgery technique, several complications including thrombosis are being increasingly reported. Much of the research so far has focused on the impact that fluid dynamics has on thrombosis. This study explores the contribution of the different foreign materials in the TAV to the initiation of thrombus formation. A steady flow loop with minimized volume was developed such that multiple experiments could be conducted with blood from a single human donor. Three conditions - control, stent-with-skirt, and whole valve - were tested using the flow loop at two different anticoagulant: reversing agent ratios (8:1 and 6:1). Serum collected from blood samples drawn at the start and end of the experiment were used to measure concentrations of D-dimer and thrombin anti-thrombin (TAT), biomarkers of thrombosis. Higher D-dimer and TAT concentrations in the stent-with-skirt compared to the valve in the 8:1 condition suggest that, over time, exposure to the stent with the skirt can shift the blood to a more prothrombotic state. Lack of significant differences between groups in the 6:1 condition indicates that when blood is already in a significantly high prothrombotic state, different materials of the TAV do not have significantly different effects on thrombus formation. The results of this study help to better understand the process of initiation of thrombus formation in TAV from a foreign materials perspective.