Numerical simulation of the leaflet designs to improve hemodynamics of mechanical heart valves

Abstract

Mechanical heart valves (MHVs) are widely implanted due to their reliability and long life span. However, patients who receive MHV implants are required and prescribed anticoagulant medication to reduce the high risk of thromboembolic complications. Although MHVs are considered as a long-term devices to save the lives of thousands of patients suffering from severe heart valve diseases, current designs could be improved based on the fundamentals of fluid mechanics in order to overcome some of the serious complications that can threaten the lives of patients, as well as improve the quality of their lives. Non-physiological blood flow and a higher level of mechanical stresses endured by the blood cells are considered as possible elements of those complications. It is believed that due to the non-physiological blood flow field through the MHVs, leaflet(s) motion can induce thromboembolism and also embolic strokes. The influence of higher levels of mechanical shear stresses, exposure time, and static flow zones behind the leaflet(s) cause significant effects to elevate platelet activation and thromboembolism formation. This research is an effort to provide further information regarding the capability of the passive flow management techniques to reduce these complications, and therefore improve the hemodynamic characteristics of blood flow to prevent high shear stress zones and blood cell damage. The objective of the current research activities is an attempt to examine pulsatile blood flow through MHVs with modified designs. In this investigation, we aim to investigate the effect of the valves with porous leaflets and compare the proposed design with the basic leaflet design. A set of steady and transient 3-dimensional models of MHVs with pulsatile, non-Newtonian turbulent blood flow were developed and investigated in order to: (1) numerically analyze the result of passive flow control techniques, (2) improve the hemodynamics of the valve, and (3) reduce the excessive levels of mechanical stresses compared to the basic bileaflet MHV. The computational models show a distinct difference in the flow field in the two designs, both of which demonstrate significant improvements in the hemodynamics of MHV.