Measurement of strain and analysis of stress in resting rat left ventricular myocardium

Omens, Jeffrey H.; MacKenna, Deidre A.; McCulloch, Andrew D.

doi:10.1016/0021-9290(93)90030-i

Cited by 128 publications

(115 citation statements)

References 18 publications

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“…(1) where E αβ are the components of Green's (Lagrange) strain tensor referred to fibre (f), crossfibre (c) and radial (r) material coordinates. C 1 -C 4 are the myocardial constitutive parameters (table 1) adapted from [13] and tuned to our kinematic data using the following approach. Given the predicted deformation provided by the FE simulation, and actual deformation from the end-diastolic tagged MR images, the value of the in vivo stiffness parameter C 1 (initially 1.2 kPa [13]) was tuned by minimizing the difference between predicted and measured LV cavity volume at the end-diastolic frame.…”

Section: Passive Left Ventricular Mechanicsmentioning

confidence: 99%

“…C 1 -C 4 are the myocardial constitutive parameters (table 1) adapted from [13] and tuned to our kinematic data using the following approach. Given the predicted deformation provided by the FE simulation, and actual deformation from the end-diastolic tagged MR images, the value of the in vivo stiffness parameter C 1 (initially 1.2 kPa [13]) was tuned by minimizing the difference between predicted and measured LV cavity volume at the end-diastolic frame. The optimal value of C 1 was 2.2 kPa, corresponding to a predicted end-diastolic LV cavity volume of 23 ml, which matched the experimental estimate.…”

Section: Passive Left Ventricular Mechanicsmentioning

confidence: 99%

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Passive Ventricular Mechanics Modelling Using MRI of Structure and Function

Wang

Lam

Ennis

et al. 2008

Medical Image Computing and Computer-Assisted Intervention – MICCAI 2008

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Patients suffering from dilated cardiomyopathy or myocardial infarction can develop left ventricular (LV) diastolic impairment. The LV remodels its structure and function to adapt to pathophysiological changes in geometry and loading conditions and this remodeling process can alter the passive ventricular mechanics. In order to better understand passive ventricular mechanics, a LV finite element model was developed to incorporate physiological and mechanical information derived from in vivo magnetic resonance imaging (MRI) tissue tagging, in vivo LV cavity pressure recording and ex vivo diffusion tensor MRI (DTMRI) of a canine heart. MRI tissue tagging enables quantitative evaluation of cardiac mechanical function with high spatial and temporal resolution, whilst the direction of maximum water diffusion (the primary eigenvector) in each voxel of a DTMRI directly correlates with the myocardial fibre orientation. This model was customized to the geometry of the canine LV during diastasis by fitting the segmented epicardial and endocardial surface data from tagged MRI using nonlinear finite element fitting techniques. Myofibre orientations, extracted from DTMRI of the same heart, were incorporated into this geometric model using a free form deformation methodology. Pressure recordings, temporally synchronized to the tissue tagging MRI data, were used to simulate the LV deformation during diastole. Simulation of the diastolic LV mechanics allowed us to estimate the stiffness of the passive LV myocardium based on kinematic data obtained from tagged MRI. This integrated physiological model will allow more insight into the regional passive diastolic mechanics of the LV on an individualized basis, thereby improving our understanding of the underlying structural basis of mechanical dysfunction in pathological conditions.

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Section: Passive Left Ventricular Mechanicsmentioning

confidence: 99%

Section: Passive Left Ventricular Mechanicsmentioning

confidence: 99%

Passive Ventricular Mechanics Modelling Using MRI of Structure and Function

Wang

Lam

Ennis

et al. 2008

Medical Image Computing and Computer-Assisted Intervention – MICCAI 2008

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“…The Cauchy stress and the second Piola-Kirchhoff stress tensors for an incompressible material are thus, e.g., using Ψ(C), 45) respectively. Although the formulations in (1.45) are convenient to use in an analytical setting, in a computational setting it is often more advantageous to use a compressible formulation, where the (near) incompressibility of biological tissues is achieved through a penalization of the volumetric terms.…”

Section: Incompressibility and Near Incompressibilitymentioning

confidence: 99%

“…As pointed out in an excellent review of cardiac models by Holzapfel and Ogden [42], the transversely isotropic models does not capture the orthotropic behavior of myocardium, but they may nevertheless be useful as they often contain fewer material parameters which may be more easily determined in vivo [43]. Common transversely isotropic models are the exponential Fung-type models (based on [44]), e.g., the model developed by Omens et al [45],…”

Section: Modeling Cardiac Mechanicsmentioning

confidence: 99%

“…3.7 the experimental values of the stresses in the fiber and cross-fiber direction for different materials are plotted as triangles and circles respectively. The materials tested and shown here are bovine, rabbit, rat and canine [45,[131][132][133]. Our model predicts much more conservatively the stresses in the fiber and sheet direction and when compared to the data from Yin et al [129], the stress in the fiber direction is about three times that what Yin reported, σ f ∼ 3 σ Yin f , and in the sheet direction it is almost exactly the same as their reported values for the cross-fiber direction, σ s ∼ σ Yin s .…”

Section: Comparison To Available Modelmentioning

confidence: 99%

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Cardiovascular Mechanics

SpringerReference

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Modeling in biomechanics plays an important role in simulating biological functions and has great potential to aid medical clinicians in determining the cause of a disease, the type of treatment or by aiding in the training of a surgical procedure. Cardiovascular diseases (CVDs) are the leading cause of mortality today. This work therefore aims at developing a framework for modeling CVDs, such as cerebral aneurysms or heart diseases with increased myofiber dispersion as seen in, e.g., hypertrophic cardiomyopathy.To this end, a three-dimensional growth model of a human saccular cerebral aneurysm is presented that includes the anisotropy of the medial layer. It is shown that including fibers in the media reduces the maximum principal stress, thickness increase and shear stress in the aneurysm wall. It is also shown that the axial pre-stretch has a large impact on the stress levels and thickness increase in the aneurysm wall.In addition, the constituents needed for the numerical implementation of a structurally based constitutive law describing the behavior of passive myocardium is shown. A comparison is made between this invariant based model and a commonly used Green-Lagrange strain component based model and it is shown that using material parameters retrieved when both models is fitted using a simple shear mode experiment, the invariant based model is better suited to predict the stress in the myocardium for other modes of deformation. The passive cardiac model is coupled together with an evolution equation responsible for generating the active stress. A model of the left ventricle (LV) is presented where pressure is calculated as a response to the change in the ventricular volume in order to ensure physiologically realistic pressure-volume loops. The influence of myocardial fiber and sheet distribution is investigated by using two different setups, a generic setup and one based on experiments. The results implies that spatial heterogeneity may play a critical role in mechanical contraction of the LV and that geometrical descriptions of deformation are needed when evaluating the accuracy of a ventricular model.Further, a novel approach to model the dispersion of both the fiber and sheet orientations evident in, especially diseased, myocardium is presented. Analytical and numerical simulations show that the dispersion parameter has great effect on myocardial deformation and stress development. The results also show that the dispersion has a significant impact on pressure-volume loops of an LV, and in future simulations the presented dispersion model for myocardium may advantageously be used together with models of, e.g., growth and remodeling of various cardiac diseases. In cases where fiber-reinforced models are extended to include the effect of distributed fiber orientations, neither the mathematical nor physical motivation for tension-compression fiber switching is clear, and in fact several choices exist for the material modeler. Therefore, methods to study such switching mechanisms is explored by ana...

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Electroconductive Biohybrid Collagen/Pristine Graphene Composite Biomaterials with Enhanced Biological Activity

et al. 2018

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Electroconductive substrates are emerging as promising functional materials for biomedical applications. Here, the development of biohybrids of collagen and pristine graphene that effectively harness both the biofunctionality of the protein component and the increased stiffness and enhanced electrical conductivity (matching native cardiac tissue) obtainable with pristine graphene is reported. As well as improving substrate physical properties, the addition of pristine graphene also enhances human cardiac fibroblast growth while simultaneously inhibiting bacterial attachment (Staphylococcus aureus). When embryonic-stem-cell-derived cardiomyocytes (ESC-CMs) are cultured on the substrates, biohybrids containing 32 wt% graphene significantly increase metabolic activity and cross-striated sarcomeric structures, indicative of the improved substrate suitability. By then applying electrical stimulation to these conductive biohybrid substrates, an enhancement of the alignment and maturation of the ESC-CMs is achieved. While this in vitro work has clearly shown the potential of these materials to be translated for cardiac applications, it is proposed that these graphene-based biohybrid platforms have potential for a myriad of other applications-particularly in electrically sensitive tissues, such as neural and neural and musculoskeletal tissues.

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Measurement of strain and analysis of stress in resting rat left ventricular myocardium

Cited by 128 publications

References 18 publications

Passive Ventricular Mechanics Modelling Using MRI of Structure and Function

Passive Ventricular Mechanics Modelling Using MRI of Structure and Function

Cardiovascular Mechanics

Electroconductive Biohybrid Collagen/Pristine Graphene Composite Biomaterials with Enhanced Biological Activity

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