Design of patient specific prosthetic aortic valve and to study its computational fluid dynamics

Cardio Vascular Disease (CVD) is the major cause of death in India as well as in many other countries of the world, in which heart valve failure plays a significant role. The two main aortic valve diseases are aortic stenosis and aortic regurgitation. If the aortic valve is damaged mildly, it can be treated by suitable interventions. On the other hand, if the damage is more severe, interventions do not control the symptoms, and only surgery is required to repair or replace the valve. Generally, it is usually replaced rather than repaired. In such case, a simulation model of valve to be implanted is necessary to determine the flow induced effects on the valve pre-operatively. This will assist physicians to go for design a customized valve that works in the optimum condition. The aim of this study was to carry out a simulation model of bi-leaflet mechanical valve and its computational fluid dynamics (CFD) analysis. A Computed Tomography (CT) image of a Indian male patient, aged 64 year was obtained and three-dimensional model of aorta was obtained using Materialise's interactive medical image control system (MIMICS) software. Using the measured dimensions from the three-dimensional model, the computer aided design (CAD) models of the following: i) normal aorta; ii) aorta with plaque at valve sinus side; and iii) bi-leaflet aortic valve were created using an AutoDesk Inventor Professional software. CFD analysis of the aorta was carried out using ANSYS software. The various parameters such as velocity, pressure and wall shear stress that affects the blood flow on all the three case studies were measured. The result showed that after implanting the valve, the blood flow pattern achieved was similar to the blood flow pattern of normal aorta. In the aorta with designed bi-leaflet valve, the percentage differences in the maximum value of velocity (ms~) as well as pressure of the blood (Pa) at the valve sinus side were found to be -20% and -19.2% respectively, when comparing to normal aorta; but, the measured valve shear stress (Pa) was same both in aorta with a bi-leaflet valve and in normal aorta. It suggests that the designed bi-leaflet valve was working satisfactorily, and it can restore the normal function of the aorta.