Device Thrombogenicity Emulator (DTE) − Design optimization methodology for cardiovascular devices: A study in two bileaflet MHV designs

• Published in: Journal of biomechanics Vol. 43; no. 12; pp. 2400 - 2409
• Main Authors: Xenos, Michalis, Girdhar, Gaurav, Alemu, Yared, Jesty, Jolyon, Slepian, Marvin, Einav, Shmuel, Bluestein, Danny
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 26.08.2010; Elsevier; Elsevier Limited
• Subjects: Anticoagulants - administration & dosage; Biological and medical sciences; Biomechanical Phenomena; Blood clots; Blood platelets; Computational fluid dynamics; Heart Valve Prosthesis - adverse effects; Hemorheology; Humans; In Vitro Techniques; Mathematical models; Mechanical circulation support (MCS); Mechanical heart valves (MHV); Medical sciences; Models, Cardiovascular; Models, Statistical; Physical Medicine and Rehabilitation; Platelet Activation; Platelet assays; Prostheses; Prosthesis Design - methods; Prosthetic heart valves (PHV); Shear stress; Stress; Stress, Mechanical; Studies; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the heart; Thrombogenic performance; Thrombosis - blood; Thrombosis - physiopathology; Thrombosis - prevention & control; Transplants & implants; Turbulence models; Prosthetic heart valves (PHV); Platelet activation; Thrombogenic performance; Computational fluid dynamics; Mechanical heart valves (MHV); Platelet assays; Mechanical circulation support (MCS); Performance evaluation; Methodology; Thrombogenesis; Mechanical prosthesis; Emulator; Heart valve; Optimization; Biomechanics; Design; Numerical simulation; Medical device; Circulatory system; Biomedical engineering
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2010.04.020

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.