In vivo dynamic strains of the ovine anterior mitral valve leaflet

Rausch, Manuel K.; Bothe, Wolfgang; Kvitting, John‐Peder Escobar; Göktepe, Serdar; Miller, D. Craig; Kuhl, Ellen

doi:10.1016/j.jbiomech.2011.01.020

Cited by 64 publications

(65 citation statements)

References 37 publications

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“…The piecewise cubic spline approximated all experimentally acquired marker coordinates v n (t) extremely well with a maximum error at any time and any marker location of less than 0.07 cm. This value is on the order of the digitization error of 0.01 ± 0.03 cm of the marker technique 4,19,32,44. Moreover, we observed no local maxima in curvature close to the original marker locations indicating a good choice for the smoothing parameter k.Figure 3aillustrates the annular excursion of the mitral valve as a measure of left ventricular long-axis shortening,25,43 displayed in an anterior view.…”

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confidence: 65%

Characterization of Mitral Valve Annular Dynamics in the Beating Heart

et al. 2011

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The objective of this study is to establish a mathematical characterization of the mitral valve annulus that allows a precise qualitative and quantitative assessment of annular dynamics in the beating heart. We define annular geometry through 16 miniature markers sewn onto the annuli of 55 sheep. Using biplane videofluoroscopy, we record marker coordinates in vivo. By approximating these 16 marker coordinates through piecewise cubic splines, we generate a smooth mathematical representation of the 55 mitral annuli. We time-align these 55 annulus representations with respect to characteristic hemodynamic time points to generate an averaged baseline annulus representation. To characterize annular physiology, we extract classical clinical metrics of annular form and function throughout the cardiac cycle. To characterize annular dynamics, we calculate displacements, strains, and curvature from the discrete mathematical representations. To illustrate potential future applications of this approach, we create rapid prototypes of the averaged mitral annulus at characteristic hemodynamic time points. In summary, this study introduces a novel mathematical model that allows us to identify temporal, regional, and inter-subject variations of clinical and mechanical metrics that characterize mitral annular form and function. Ultimately, this model can serve as a valuable tool to optimize both surgical and interventional approaches that aim at restoring mitral valve competence.

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Characterization of Mitral Valve Annular Dynamics in the Beating Heart

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“…Yet, with most conventional test setups, characterizing living membranes in vivo over long periods of time remains challenging. One possibility would be to label characteristic anatomic landmarks with implanted markers, follow them chronically, and reconstruct the surface geometry using biplane videofluoroscopy and continuum mechanics [41]. However, this approach is not only expensive and highly invasive, but also relies on a sophisticated, difficult-to-reproduce experimental setup.…”

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confidence: 99%

Characterization of living skin using multi-view stereo and isogeometric analysis

et al. 2014

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Skin is our interface with the outside world. In its natural environment, it displays unique mechanical characteristics such as prestretch and growth. While there is a general agreement on the physiological importance of these features, they remain poorly characterized, mainly because they are difficult to access with standard laboratory techniques. Here we present a new, inexpensive technique to characterize living skin using multi-view stereo and isogeometric analysis. Based on easy-to-create hand-held camera images, we quantify prestretch, deformation, and growth in a controlled porcine model of chronic skin expansion. Over a period of five weeks, we gradually inflate an implanted tissue expander, take weekly photographs of the experimental scene, reconstruct the geometry from a tattooed surface grid, and create parametric representations of the skin surface. After five weeks of expansion, our method reveals an average area prestretch of 1.44, an average area stretch of 1.87, and an average area growth of 2.25. Area prestretch is maximal in the ventral region with 2.37, area stretch and area growth are maximal above the center of the expander with 4.05 and 4.81. Our study has immediate impact on understanding living skin to optimize treatment planning and decision making in plastic and reconstructive surgery. Beyond these direct implications, our experimental design has broad applications in clinical research and basic sciences: It serves as a simple, robust, low cost, easy-to-use tool to reconstruct living membranes, which are difficult to characterize in a conventional laboratory setup.

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“…The majority of previous studies evaluating MV deformation and leaflet tissue stress parameters have used surgically implanted crystals in animal models [1][2][3]6,8,10,13 and camera recordings of crystals motion. Other studies have combined similar in vivo data with parameterized elasticity models implemented by customized finite elements software.…”

Section: Modelingmentioning

confidence: 99%

“…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.…”

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

Zekry¹,

Freeman

Jajoo

et al. 2016

Circ: Cardiovascular Imaging

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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...

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In vivo dynamic strains of the ovine anterior mitral valve leaflet

Cited by 64 publications

References 37 publications

Characterization of Mitral Valve Annular Dynamics in the Beating Heart

Characterization of Mitral Valve Annular Dynamics in the Beating Heart

Characterization of living skin using multi-view stereo and isogeometric analysis

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

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