Abstract 20561: Correlation Between Transmitral Vortex Formation and Mitral Valve's Leaflet Length
Background: Several studies have previously confirmed the presence of vortical flow structures that develop along with the propulsive transmitral jet. These vortices are found as indicator of diastolic function. Recent works also report that in a normal heart, the transmitral vortex tends to be more asymmetric than symmetric potentially due to asymmetry of the mitral valve's leaflets. In the present work, we have studied the effect of mital valve leaflets' length on the shape of the transmitral vortex using a dynamic bi-leaflet mitral bioprosthesis.
Methods: This study has been accomplished using a left heart pulsed flow simulator. Two bi-leaflet mitral bioprosthetics (25mm) with different leaflet lengths (11mm and 25mm) that mimic the dynamic motion of the mitral valve's saddle annulus were used for comparison. The flow characteristic information was captured by high speed Digital Particle Image Velocimetry (DPIV).
Results: Flow fields downstream of each valve were mapped using DPIV. Figures A and B show the schematic of transmitral vortex formation downstream each valve. Figures C and D show the velocity vector fields overlaid on the particle field at mid diastole for both valves, respectively. A symmetric, donut-shape vortex was formed in case of the mitral valve with short leaflets while an asymmetric, unstable vortex was found downstream the mitral valve with long leaflets, despite the identical cardiac cycles, pressure drop, afterload and the preload in both cases.
Conclusion: Based on the current in-vitro studies, change in mitral leaflet's length could vastly affect the transmitral vortex formation due to the altered flow-wall interaction. Our data confirmed that the stability and the symmetry of transmitral vortex are remarkably influenced by the leaflet length. As the leading vortex transfers extra momentum from left atrium to left ventricle, efficient blood transport toward the aorta can be significantly affected based on the mitral valve leaflets length.
- © 2010 by American Heart Association, Inc.