Material properties of the ovine mitral valve anterior leaflet in vivo from inverse finite element analysis

We measured leaflet displacements and used inverse finite-element analysis to define, for the first time, the material properties of mitral valve (MV) leaflets in vivo. Sixteen miniature radiopaque markers were sewn to the MV annulus, 16 to the anterior MV leaflet, and 1 on each papillary muscle tip in 17 sheep. Four-dimensional coordinates were obtained from biplane videofluoroscopic marker images (60 frames/s) during three complete cardiac cycles. A finite-element model of the anterior MV leaflet was developed using marker coordinates at the end of isovolumic relaxation (IVR; when the pressure difference across the valve is ∼0), as the minimum stress reference state. Leaflet displacements were simulated during IVR using measured left ventricular and atrial pressures. The leaflet shear modulus ( Gcirc-rad) and elastic moduli in both the commisure-commisure ( Ecirc) and radial ( Erad) directions were obtained using the method of feasible directions to minimize the difference between simulated and measured displacements. Group mean (±SD) values (17 animals, 3 heartbeats each, i.e., 51 cardiac cycles) were as follows: Gcirc-rad= 121 ± 22 N/mm2, Ecirc= 43 ± 18 N/mm2, and Erad= 11 ± 3 N/mm2( Ecirc> Erad, P < 0.01). These values, much greater than those previously reported from in vitro studies, may result from activated neurally controlled contractile tissue within the leaflet that is inactive in excised tissues. This could have important implications, not only to our understanding of mitral valve physiology in the beating heart but for providing additional information to aid the development of more durable tissue-engineered bioprosthetic valves.

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QUANTIFICATION OF IN VIVO MITRAL VALVE MATERIAL PROPERTIES USING INVERSE FINITE ELEMENT ANALYSIS

Journal of Biomechanics ◽

10.1016/s0021-9290(08)70119-2 ◽

2008 ◽

Vol 41 ◽

pp. S119

Author(s):

Gaurav Krishnamurthy ◽

Daniel B. Ennis ◽

Akinobu Itoh ◽

Wolfgang Bothe ◽

Julia Swanson ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Mitral Valve ◽

Material Properties ◽

Element Analysis ◽

Inverse Finite Element Analysis

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Quantification of In Vivo Stresses in the Ovine Anterior Mitral Valve Leaflet

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-192295 ◽

2008 ◽

Author(s):

Gaurav Krishnamurthy ◽

Akinobu Itoh ◽

Wolfgang Bothe ◽

Daniel B. Ennis ◽

Julia C. Swanson ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Mitral Valve ◽

Material Properties ◽

Element Analysis ◽

Mitral Valve Leaflet ◽

Mitral Valves ◽

Mitral Repair ◽

Inverse Finite Element Analysis

Mitral valve (MV) disease affects millions worldwide. An important goal of present-day heart valve research is to create bioengineered tissue valves to replace diseased mitral valves, if it is judged that mitral repair will not be durable. The design of such valves will pivot on understanding the stresses acting in the native MV leaflets to design a bioprosthesis which will withstand these stresses. In order to quantify such stresses in vivo, we utilized radiopaque marker technology and performed an “inverse” finite element analysis of the resulting 4-D data to determine the material properties of the anterior MV leaflet in the beating ovine heart. We then used these material properties in a “forward” finite element analysis to estimate the stresses in the native anterior MV leaflet.

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Finite-element analysis of stress in the canine diaphragm

Journal of Applied Physiology ◽

10.1152/jappl.1994.76.5.2070 ◽

1994 ◽

Vol 76 (5) ◽

pp. 2070-2075 ◽

Cited By ~ 15

Author(s):

S. S. Margulies ◽

G. T. Lei ◽

G. A. Farkas ◽

J. R. Rodarte

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Element Model ◽

Biaxial Stress ◽

Principal Stresses ◽

Element Analysis ◽

Transdiaphragmatic Pressure ◽

Sigma 1

Stress in the diaphragm, transdiaphragmatic pressure, and diaphragm shape are interrelated by a balance of forces. Using precise in vivo measurements of diaphragm shape and transdiaphragmatic pressure distribution in combination with finite-element analysis (ANSYS), we determined the direction and magnitude of stress in the passive diaphragm at relaxation volume. Lead spheres sutured along muscle bundles identified muscle bundle location and orientation in vivo. The x, y, and z coordinates of the lead spheres and entire surface of the diaphragm, excluding the zone of apposition, were determined to within 1.4 mm. Thin shell elements were used to construct a finite-element model of the diaphragm with a 2.1- to 4.2-mm internodal spacing. The diaphragm was assumed to have a uniform thickness of 2.5 mm, and magnitude and direction of the principal stresses were computed. The results show that 1) diaphragm stress is nonuniform and anisotropic (i.e., varies both with location on diaphragm surface and direction examined), 2) largest stress (sigma 1) is aligned with muscle bundles and is two to four times larger than sigma 2 (perpendicular to sigma 1 in diaphragm plane), and 3) stress along the muscle bundles is larger in vivo under conditions of biaxial stress than at same length in vitro under uniaxial stress. Although diaphragm stress and tension have often been assumed to be uniform, our finding that stress is oriented primarily along the muscle fibers should be considered in future models of the diaphragm.(ABSTRACT TRUNCATED AT 250 WORDS)

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In vivo characterization of mechanical tissue properties of internal organs using endoscopic microscopy and inverse finite element analysis

Journal of Biomechanics ◽

10.1016/j.jbiomech.2010.09.019 ◽

2011 ◽

Vol 44 (3) ◽

pp. 487-493 ◽

Cited By ~ 12

Author(s):

David Schwenninger ◽

Stefan Schumann ◽

Josef Guttmann

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Internal Organs ◽

Element Analysis ◽

Tissue Properties ◽

In Vivo Characterization ◽

Inverse Finite Element Analysis ◽

Mechanical Tissue

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Isolating the effects of equine hoof shape measurements on capsule strain with finite element analysis

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0038-1632762 ◽

2003 ◽

Vol 16 (02) ◽

pp. 67-75 ◽

Cited By ~ 22

Author(s):

H. L. McClinchey ◽

J. C. Jofriet ◽

J. J. Thomason

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Finite Element Methods ◽

In Vivo Studies ◽

Finite Element Models ◽

Element Analysis ◽

Toe Angle ◽

Equine Hoof

SummaryThe shape of the equine hoof capsule affects how weightbearing forces are resisted by the capsule and are transmitted to deeper structures within the hoof. Our aim was to isolate the effects of several measurements describing hoof shape on strains and stresses in the hoof capsule. Multiple finite-element models are constructed with toe angles in the range 42° to 58°, heel angles from 34° to 50°, toe lengths of 8.5 to11.5 cm, and medial and lateral angles from 68° to 83°. Strain at the toe is inversely related to toe angle, and not strongly affected by heel angle; it increases with toe length distally on the toe, but decreases near the coronary border. Varying medial and lateral angles show that more upright walls have less strain at the quarters. This study demonstrates the effectiveness of finite element methods in complementing in vitro and in vivo studies of hoof mechanics.

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Using Inverse Finite Element Analysis to Obtain Passive Mechanical Behavior of Abdominal Wall

Jornada de Jóvenes Investigadores del I3A ◽

10.26754/jji-i3a.201501629 ◽

1970 ◽

Vol 3 ◽

pp. 17-18

Author(s):

Raquel Simón-Allué ◽

Assad Oberai ◽

Begoña Calvo

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Mechanical Behavior ◽

Inverse Analysis ◽

Mechanical Response ◽

Abdominal Muscle ◽

Hernia Surgery ◽

Element Analysis ◽

Inverse Finite Element Analysis

In this work we develop a methodology to characterize in vivo the passive mechanical behavior of abdominal muscle, using for that finite element simulations combined with inverse analysis and optimization algorithms. The knowledge of the mechanical response of the muscle is needed to determine the features of the mesh in cases of hernia surgery.

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