Abstract 15189: Creation of Nonischemic Functional Mitral Regurgitation by Annular Dilatation in an in vivo Swine Model
Background: Mechanisms and treatments of nonischemic functional mitral regurgitation (NIMR) remain to be fully established because of a lack of proper large animal models. We developed a novel technique of NIMR creation in a swine model by placing multiple small annular incisions.
Methods: Ex-vivo experiments using isolated swine hearts (n=10) showed a 15% larger mitral annular area (6.8 to 7.8 cm2) after 16 incisions along the posterior mitral annulus when the ventricle was pressurized. Next, in an in vivo swine model (n=7, 46.4±2.2kg) NIMR creation was done by making 14-26 2-mm-size annular incisions through the left atrial wall using the Cardioport video-assisted imaging system in the beating heart, followed by euthanasia after 4 weeks (n=4) or 6 weeks (n=3). Three-dimensional (3-D) echocardiography was obtained before NIMR creation and at euthanasia, measuring vena contracta area, mitral annular dimension, left ventricular volume, and inter-papillary muscle distance.
Results: NIMR creation resulted in mild-moderate regurgitation, and increased vena contracta area. NIMR creation changed mitral valve geometry from saddle-shape to planar, and increased the annular area predominantly in the anteroposterior direction. In contrast, NIMR creation did not significantly change left ventricular volume and inter-papillary muscle distance. Longer follow-up period did not significantly affect these outcomes.
Conclusions: NIMR can be successfully created in a beating-heart model and results in dilatation and 3-D geometric changes in the mitral annulus. This model permits experimental validation of new annuloplasty rings and valve-repair techniques.
- © 2012 by American Heart Association, Inc.