Effect of glutaraldehyde based cross-linking on the viscoelasticity of mitral valve basal chordae tendineae

Background Mitral valve failure can require repair or replacement. Replacement bioprosthetic valves are treated with glutaraldehyde prior to implantation. The aim of this study was to determine the changes in mechanical properties following glutaraldehyde fixation of mitral valve chordae. Methods To investigate the impact of glutaraldehyde on mitral valve chordae, 24 basal chordae were dissected from four porcine hearts. Anterior and posterior basal (including strut) chordae were used. All 24 chordae were subjected to a sinusoidally varying load (mean level 2N, dynamic amplitude 2N) over a frequency range of 0.5–10 Hz before and after glutaraldehyde treatment. Results The storage and loss modulus of all chordal types decreased following glutaraldehyde fixation. The storage modulus ranged from: 108 to 119 MPa before fixation and 67.3–87.4 MPa following fixation for basal chordae; 52.3–58.4 MPa before fixation and 47.9–53.5 MPa following fixation for strut chordae. Similarly, the loss modulus ranged from: 5.47 to 6.25 MPa before fixation and 3.63–4.94 MPa following fixation for basal chordae; 2.60–2.97 MPa before fixation and 2.31–2.93 MPa following fixation for strut chordae. Conclusion The viscoelastic properties of mitral valve chordae are affected by glutaraldehyde fixation; in particular, the reduction in storage moduli decreased with an increase in chordal diameter

Geometric description for the anatomy of the mitral valve: A review

The mitral valve is a complex anatomical structure whose physiological functioning relies on the biomechanical properties and structural integrity of its components. Their compromise can lead to mitral valve dysfunction, associated with morbidity and mortality. Therefore, a review on the morphometry of the mitral valve is crucial, more specifically on the importance of valve dimensions and shape for its function. This review initially provides a brief background on the anatomy and physiology of the mitral valve, followed by an analysis of the morphological information available. A characterisation of mathematical descriptions of several parts of the valve is performed and the impact of different dimensions and shape changes in disease is then outlined. Finally, a section regarding future directions and recommendations for the use of morphometric information in clinical analysis of the mitral valve is presented

Computer and experimental modelling of blood flow through the mitral valve of the heart

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Subject-specific knee joint model: Design of an experiment to validate a multi-body finite element model

International audienceThe availability of a validated subject-specific model of the knee joint would be extremely useful for the orthopaedic surgeon in evaluating the biomechanics of the joint of a patient, especially when suspecting an injury of one or more components. The aim of this paper was to describe a procedure designed and developed to validate a subject-specific model of the human knee. The proposed approach considers the use of clinical images to create a multi-body finite element model of a healthy knee. The same joint must undergo an experimental test aimed at collecting the data necessary to validate the model predictions. Therefore, the experimental set-up must be designed to monitor all the degrees of freedom of the joint, allowing the replication of the loading conditions in silico with a finite element (FE) model. At the moment, an animal model is used to verify the accuracy and repeatability of the developed procedure

Frequency and diameter dependent viscoelastic properties of mitral valve chordae tendineae

This study aimed to characterise viscoelastic properties of different categories of chordae tendineae over a range of frequencies. Dynamic Mechanical Analysis (DMA) was performed using a materials testing machine. Chordae (n=51) were dissected from seven porcine hearts and categorised as basal, marginal, strut or commissural. Chordae were loaded under a sinusoidally varying tensile load at a range of frequencies between 0.5 and 5 Hz, both at a standardised load (i.e. same mean load of 4 N for all chordae) and under chordal specific loading (i.e. based on in vivo loads for different chordae). Storage modulus and stiffness were frequency-dependent. Loss modulus and stiffness were frequency-independent. Storage and loss moduli, but not stiffness, decreased with chordal diameter. Therefore, strut chordae have the lowest moduli and marginal chordae the highest moduli. The hierarchy of dynamic storage and loss moduli is: marginal, commissural, basal and strut. In conclusion, viscoelastic properties of chordae are dependent on both frequency and chordal type. Future/novel replacement chordal materials should account for frequency and diameter dependent viscoelastic properties of chordae tendineae