title: Device Thrombogenicity Emulator (DTE)--design optimization methodology for cardiovascular devices: a study in two bileaflet MHV designs.
abstract: Patients who receive prosthetic heart valve (PHV) implants require mandatory anticoagulation medication after implantation due to the thrombogenic potential of the valve. Optimization of PHV designs may facilitate reduction of flow-induced thrombogenicity and reduce or eliminate the need for post-implant anticoagulants. We present a methodology entitled Device Thrombogenicty Emulator (DTE) for optimizing the thrombo-resistance performance of PHV by combining numerical and experimental approaches. Two bileaflet mechanical heart valves (MHV) designs, St. Jude Medical (SJM) and ATS, were investigated by studying the effect of distinct flow phases on platelet activation. Transient turbulent and direct numerical simulations (DNS) were conducted, and stress loading histories experienced by the platelets were calculated along flow trajectories. The numerical simulations indicated distinct design dependent differences between the two valves. The stress loading waveforms extracted from the numerical simulations were programmed into a hemodynamic shearing device (HSD), emulating the flow conditions past the valves in distinct 'hot-spot' flow regions that are implicated in MHV thrombogenicity. The resultant platelet activity was measured with a modified prothrombinase assay, and was found to be significantly higher in the SJM valve, mostly during the regurgitation phase. The experimental results were in excellent agreement with the calculated platelet activation potential. This establishes the utility of the DTE methodology for serving as a test bed for evaluating design modifications for achieving better thrombogenic performance for such devices.
authors.affiliation: Department of Biomedical Engineering, Stony Brook University, HSC T18-030, Stony Brook, NY 11794-8181, USA.
authors.forename: Michalis
authors.initials: M
authors.lastname: Xenos
authors.forename: Gaurav
authors.initials: G
authors.lastname: Girdhar
authors.forename: Yared
authors.initials: Y
authors.lastname: Alemu
authors.forename: Jolyon
authors.initials: J
authors.lastname: Jesty
authors.forename: Marvin
authors.initials: M
authors.lastname: Slepian
authors.forename: Shmuel
authors.initials: S
authors.lastname: Einav
authors.forename: Danny
authors.initials: D
authors.lastname: Bluestein
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage; D001696:Biomechanical Phenomena; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D018056:Hemorheology; D006801:Humans; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D015233:Models, Statistical; D015539:Platelet Activation; D011474:Prosthesis Design / Q000379:methods*; D013314:Stress, Mechanical; D013927:Thrombosis / Q000097:blood / Q000503:physiopathology / Q000517:prevention & control*
chemical_list: D000925:Anticoagulants