Even though the mechanical heart valve (MHV) has been used routinely in clinical practice for over 60 years, the occurrence of serious complications such as blood clotting remains to be elucidated. This paper reviews the progress that has been made over the years in terms of numerical simulation method and the contribution of abnormal flow toward blood clotting from MHVs in the aortic position. It is believed that this review would likely be of interest to some readers in various disciplines, such as engineers, scientists, mathematicians and surgeons, to understand the phenomenon of blood clotting in MHVs through computational fluid dynamics.

In this study, the fluid structure interaction (FSI) method was utilized to investigate the hemodynamic effects between normal aorta and aorta with Transcatheter Aortic Valve Implantation (TAVI) of paravalvular leakage (PVL). A 3D model of patient specific aorta with annulus diameter of 27.3 mm was developed using MIMICS software. In this research, a similar TAVI valve model by referring to SXT 26 Edwards SAPIENT valve was drawn using CATIA software with valve opening of 100%. The two way of fluid structure interaction analysis has been performed using ANSYS 14.5 software (ANSYS Inc. Canonsburg, PA, USA). The results revealed that the undersized TAVI valve lead to PVL. It was noticed that the PVL happened at the gap in-between the TAVI valve and annulus diameter which is not completely round in shape. This phenomenon produced recirculation flow at the right side of ascending aorta after the flow passing through the valve. It has been proven that the PVL caused a huge impact on the losses of the mass flow rate and also recirculation of blood flow which may lead to blood thrombosis. Furthermore, the data shows that PVL causes higher aortic wall deformation instead of normal aortic condition and may lead to migration of the valve. Consequently, PVL may cause other serious problems such as stroke, arrhythmias and coronary ischemia, which required reoperation.

This study investigated the impact of paravalvular leakage (PVL) in relation to the different valve openings of the transcatheter aortic valve implantation (TAVI) valve using the fluid structure interaction (FSI) approach. Limited studies were found on the subject of FSI with regards to TAVI-PVL condition, which involves both fluid and structural responses in coupling interaction. Hence, further FSI simulation with the two-way coupling method is implemented to investigate the effects of hemodynamics blood flow along the patient-specific aorta model subjected to the interrelationship between PVL and the different valve openings using the established FSI software ANSYS 16.1. A 3D patient-specific aorta model is constructed using MIMICS software. The TAVI valve identical to Edward SAPIEN XT 26 (Edwards Lifesciences, Irvine, California), at different Geometrical Orifice Areas (GOAs), is implanted into the patient’s aortic annulus. The leaflet opening of the TAVI valve is drawn according to severity of GOA opening represented in terms of 100%, 80%, 60%, and 40% opening, respectively. The result proved that the smallest percentage of GOA opening produced the highest possibility of PVL, increased the recirculatory flow proximally to the inner wall of the ascending aorta, and produced lower backflow velocity streamlines through the side area of PVL region. Overall, 40% GOA produced 89.17% increment of maximum velocity magnitude, 19.97% of pressure drop, 65.70% of maximum WSS magnitude, and a decrement of 33.62% total displacement magnitude with respect to the 100% GOA.