Patient-Specific Quantitation of Mitral Valve Strain by Computer Analysis of Three-Dimensional Echocardiography

Abstract

T he normally functioning mitral valve (MV) is complex; the saddle shape of the mitral annulus has been shown to influence leaflet deformation and to reduce stress on the valve leaflets. [1][2][3][4][5][6] The leaflets tissue properties and morphology are important as well. Myxomatous degeneration is the most common pathology in patients with mitral regurgitation (MR). 7 These organic MVs are characterized by alterations in collagen and cellular composition leading to thick and excess leaflet tissue, flattened and enlarged mitral annulus, and weak chordae. Consequently, leaflets may prolapse or flail, resulting in significant MR. MV deformation during the cardiac cycle can be variable within various regions of the normal MV and in valve disease states. The majority of previous studies evaluating MV strain were based on animal models, whereby crystals attached to the mitral apparatus and imaged with 3-dimensional (3D) cameras provided strain measurements. 1,2,[8][9][10][11][12][13] With recent technical advances in 3D echocardiography, dynamic volumetric imaging and tracking of the MV apparatus can now be performed in real time and enable direct computerized study of MV motion and deformation in humans, without the need for invasive instrumentation. The aim of the present study was, first, to quantitate patient-specific global and regional dynamic deformations of the MV apparatus in a normal patient population and, second, to evaluate whether patients with organic MR have significant alterations in the intensity of global strain and its regional distribution. See Editorial by WatanabeSee Clinical Perspective Methods Patient PopulationThe patient population was prospectively enrolled and included individuals with a normal heart by echocardiography who underwent a transesophageal echocardiogram for clinical reasons suchBackground-A paucity of data exists on mitral valve (MV) deformation during the cardiac cycle in man. Real-time 3-dimensional (3D) echocardiography now allows dynamic volumetric imaging of the MV, thus enabling computerized modeling of MV function directly in health and disease. Methods and Results-MV imaging using 3D transesophageal echocardiography was performed in 10 normal subjects and 10 patients with moderate-to-severe or severe organic mitral regurgitation. Using proprietary 3D software, patientspecific models of the mitral annulus and leaflets were computed at mid-and end-systole. Strain analysis of leaflet deformation was derived from these models. In normals, mean strain intensity averaged 0.11±0.02 and was higher in the posterior leaflet than in the anterior leaflet (0.13±0.03 versus 0.10±0.02; P<0.05). Mean strain intensity was higher in patients with mitral regurgitation (0.15±0.03) than in normals (0.11±0.02; P=0.05). Higher mean strain intensity was noted for the posterior leaflet in both normal and organic valves. Regional valve analysis revealed that both anterior and posterior leaflets have the highest strain concentration in the commissural zone, and the boundary zone near the annu...

Mitral Valve Leaflet Remodeling After Myocardial Infarction

“…Leaflets can even stretch, probably contributing to effective valve closure. 20,21 Tethering force, closing force, leaflet pathology, and function…, there are several confounding factors based on the heterogeneous underlining ischemic condition in each individual. Although the study of Beaudoin et al 13 has made an important contribution, there is still much to be learned before we have a complete understanding of the pathophysiology of ischemic mitral regurgitation.…”

The Future of Cardiovascular Imaging

“…Multimodality imaging can provide detailed 3D images of the mitral apparatus and can help us better understand potential mechanisms underlying various mitral valve disease processes. Refined strain measurement of the annulus and the leaflets themselves in the normal and disease state 47,48 are advancing knowledge of the interplay between geometry and function, and the transition from an adaptive to a maladaptive or dysfunctional response, as well ( Figure 3). The old concept of a mitral valve that remains constant throughout adult life is now clearly recognized as being incorrect.…”

“…El color de las intensidades del esfuerzo tienen un rango desde el naranja oscuro para el esfuerzo alto hasta el azul oscuro para el esfuerzo bajo. Reimpreso de Ben Zekry et al 47 con autorización del editor. Copyright © 2016, American Heart Association, Inc. El foco en las enfermedades valvulares regurgitantes, como la regurgitación mitral, se ha centrado principalmente en el volumen regurgitado, el tamaño del orificio regurgitante funcional y el impacto de la sobrecarga de volumen en la geometría y función de la cavidad junto con la capacidad funcional.…”

“…Las imágenes de multimodalidad pueden proveer imágenes detalladas en 3D del aparato mitral y pueden ayudarnos a comprender mejor los mecanismos potenciales subyacentes a varios procesos de enfermedad valvular mitral. La medición refinada de la deformación del anillo y de las valvas mismas en estado normal y enfermo 47,48 está promoviendo el conocimiento de la interacción entre geometría y función, y también de la transición de una respuesta adaptativa a una mal adaptativa o disfuncional (Figura 3). El viejo concepto de una válvula mitral que permanece constante a través de la vida adulta está ahora claramente reconocido como incorrecto.…”

The Mitral Valve Complex: Divine Perfection

“…In this issue of Circulation: Cardiovascular Imaging, Ben Zekry et al 18 attempt to quantitate patient-specific global strain of the mitral valve apparatus and its regional dynamic deformations with the use of a novel computerized tracking system for volumetric images by 3D transesophageal echocardiography in a normal patient population and then compare the results with those measured in patients with organic MR. What is new in their tracking system compared with previous computerized simulation systems is that the strain analysis of leaflet deformation in this study is based on valve anatomy without any computer assumption on tissue elasticity.…”