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Objective: Multiple studies have demonstrated that perturbation of mitral valve mechanics promotes bioarchitectural remodeling that may adversely effect patterns of valvular loading and stress distribution. This phenomenon may contribute to the disappointing durability of mitral valve repair seen in multiple patient populations even in the context of open repair where direct visualization is possible. As minimally invasive mitral valve interventions are refined and become more common-place, we believe it will be essential to develop quantitative methods and indexes for describing three-dimensional geometry. We believe that real-time three-dimensional echocardiography (rt-3DE) is uniquely applicable to this task.
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Liam P. Ryan1, Benjamin M. Jackson1, Theodore J. Plappert2, Martin G. St. John-Sutton2, Robert C. Gorman1, Joseph H. Gorman, III1.
1Harrison Department of Surgical Research, University of Pennsylvania School of Medicine, Philadelphia, PA, USA, 2Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
Methods: Gated full-volume, trans-thoracic images of the mitral valve were acquired in five normal, adult male subjects with a Philips Sonos 7500 platform and a 2-4 MHz X4 hand held matrix transducer over 8 cardiac cycles. Both Gaussian curvature and curvature heterogeneity (STDEV over 0.49 mm2) were calculated across a continuous surface mesh and superimposed upon three-dimensional renderings constructed from 600-1200 data points for each mitral valve.
Results: In each of the five normal human mitral valves, there was a prominent hyperbolic region along the meridian of the anterior leaflet as well as symmetric elliptical regions on the medial and lateral surfaces of the anterior leaflet immediately adjacent to the annulus. Additionally, there was a complex pattern of alternating elliptical and hyperbolic geometry over the belly of the posterior leaflet in each subject. There were scattered foci of highly heterogeneous curvature across all leaflet regions in each subject - however, this heterogeneity was most prominent in the mid-posterior (P2) leaflet. These findings are illustrated in the accompanying figure.
Conclusions: There are reproducible geometric patterns present in the normal human mitral that are detectable with rt-3DE. These may serve as geometric targets for minimally invasive interventions in which direct visualization of the mitral valve is not possible. Interestingly, focally high geometric heterogeneity exists within the P2 leaflet region which is the most common site of leaflet flail.
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