Effective orifice area assessment in BI-leaflet mechanical valves by MRI,

Abstract

International audienceEffective orifice area (EOA) and mean pressure gradientare routine echocardiographic measurements of valvularprosthesis function in both the mitral and aortic position.EOA computation is based on the continuity equationand is used to describe the “effective” orifice formed bythe flow traversing a geometrical orifice. In the case ofbi-leaflet biomechanical valvular prosthesis (BMHV),the orifice of the valve is divided into 3 zones. BMHVperformance assessment by MRI have been described inthe in-vitro setting in [1] using the maximum pressuregradient. Additionally, a method using jet layer has beenused to detect EOA dynamically [2]. 4D-PC flowsequences enable measurement of three velocitycomponents by MRI with a temporal resolutionaveraging (~ 30 msec). In patients with a BMHV,despite the metallic blurring due to the valve structure,MRI examination enhances both anatomical andhemodynamic diagnosis. Aim of this work is to assessthe capacity of MRI to measure BMHV EOA by 4D-PCflowMRI, using simple computational fluid dynamic(CFD) simulation for validation