Abstract 12281: Matrix Remodeling in Native Atrioventricular Valves’ Leaflets in Response to Mechanical Loading
Introduction: One of the key determinants in functionality of natural heart valves is their matrix ability to properly remodel in response to the constantly varied physiological load. Any disruption in this capacity would cause improper orientation of the matrix fibers with respect to the blood flow and may result in leaflet stiffening, shortening, matrix degradation, and finally early failure of the valve. In this study, we have characterized the effect of mechanical loading on native valves’ leaflets microstructure using Second Harmonic Generation (SHG) microscopy.
Methods: Fresh natural porcine tricuspid and mitral valves’ leaflets were cut and prepared for SHG microscopy. The specimens were imaged live during the relaxed and loading phases for uni- and bi-axial states. SHG images were acquired by a Zeiss laser microscope excited with 900nm laser and filtered from 450nm to 465nm. Image analysis was performed on the data using a Fourier decomposition method to mathematically seek changes in fiber orientation.
Results: Figures 1A to 1C show the matrix map of a fresh porcine mitral leaflet tissue at the 40μ depth prior to loading, under uniaxial and biaxial loadings, respectively. Figures 1D to 1F show a fresh porcine tricuspid leaflet at the same depth in relaxed, uniaxial, and biaxial loadings, respectively. Figures 1G and 1H are the comparison of changes in fiber orientation versus depth in which the image was taken for mitral and tricuspid leaflets, respectively. For the mitral anterior leaflet, the fibers arrange almost in line with uniaxial load in all different depths; however, for tricuspid valve, they align with the load only in deeper layers. Both valves’ biaxial responses were similar with fibers aligning in between the two principal axes of the loads.
Conclusions: This study suggests that the characteristics and the alignment of the matrix fibers in mitral and tricuspid leaflets vary in response to uniaxial but not to bi-axial mechanical loading conditions.
Author Disclosures: S. Alavi: None. A. Sinha: None. A. Kheradvar: None.
This research has received full or partial funding support from the American Heart Association.
- © 2014 by American Heart Association, Inc.