The Influence of the Aortic Root Geometry on Flow Characteristics of a Bileaflet Mechanical Heart Valve

TL;DR

This study investigates how variations in aortic root geometry, such as stenosis and insufficiency, influence flow dynamics and potential blood damage risks downstream of a bileaflet mechanical heart valve.

Contribution

It provides new insights into how geometrical changes affect flow patterns and shear stresses, validated by experimental data, highlighting potential risks for blood damage.

Findings

Increased stenosis and insufficiency lead to more flow separation.

Flow velocity and fluctuations increase with geometrical abnormalities.

Higher shear stresses may elevate blood damage and clot risks.

Abstract

Bileaflet mechanical heart valves have one of the most successful valve designs for more than 30 years. These valves are often used for aortic valve replacement, where the geometry of the aortic root sinuses may vary due to valvular disease and affect valve performance. Common geometrical sinus changes may be due to valve stenosis and insufficiency. In the current study, the effect of these geometrical changes on the mean flow and velocity fluctuations downstream of the valve and aortic sinuses were investigated. The study focused on the fully-open leaflet position where blood velocities are close to their maximum. Simulation results were validated using previous experimental laser Doppler anemometry (LDA) measurements. Results showed that as the stenosis and insufficiency increased there were more flow separation and increased local mean velocity downstream of the leaflets. In addition, the detected elevated velocity fluctuations were associated with higher Reynolds shear stresses levels, which may increase the chances of blood damage and platelet activation and may lead to increased risk of blood clot formation.