Material properties of aged human mitral valve leaflets

Pham, Thuy M.; Sun, Wei

doi:10.1002/jbm.a.34939

Cited by 53 publications

(40 citation statements)

References 74 publications

(134 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fortunately, in the past decade, the mechanical testing techniques and constitutive modeling in cardiovascular mechanics have improved tremendously. Human tissue material properties can now be tested extensively (Pham and Sun, 2013), modeled and implemented in computational studies (Wang and Sun, 2013). Improved computational models of MV has evolved (Krishnamurthy et al, 2009; Kunzelman et al, 1993; Pouch et al, 2012; Prot et al, 2009; Stevanella et al, 2011; Weinberg and Kaazempur Mofrad, 2007) and predicted several diseased states (Kunzelman et al, 1997; Prot et al, 2010; Wenk et al, 2010; Xu et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Tension to passively cinch the mitral annulus through coronary sinus access: An ex vivo study in ovine model

Bhattacharya

Pham

et al. 2014

Journal of Biomechanics

Self Cite

View full text Add to dashboard Cite

Introduction The transcatheter mitral valve repair (TMVR) technique utilizes a stent to cinch a segment of the mitral annulus (MA) and reduces mitral regurgitation. The cinching mechanism results in reduction of the septal-lateral distance. However, the mechanism has not been characterized completely. In this study, a method was developed to quantify the relation between cinching tension and MA area in an ex vivo ovine model. Method The cinching tension was measured from a suture inserted within the coronary sinus (CS) vessel with one end tied to the distal end of the vessel and the other end exited to the CS ostium where it was attached to a force transducer on a linear stage. The cinching tension, MA area, septal-lateral (S-L) and commissure-commissure (C-C) diameters and leakage was simultaneously measured in normal and dilated condition, under a hydrostatic left ventricular pressure of 90 mmHg. Results The MA area was increased up to 22.8% after MA dilation. A mean tension of 2.1 ± 0.5 N reduced the MA area by 21.3 ± 5.6% and S-L diameter by 24.2 ± 5.3%. Thus, leakage was improved by 51.7 ± 16.2 % following restoration of normal MA geometry. Conclusion The cinching tension generated by the suture acts as a compensation force in MA reduction, implying the maximum tension needed to be generated by annuloplasty device to restore normal annular size. The relationship between cinching tension and the corresponding MA geometry will contribute to the development of future TMVR devices and understanding of myocardial contraction function.

show abstract

Section: Discussionmentioning

confidence: 99%

Tension to passively cinch the mitral annulus through coronary sinus access: An ex vivo study in ovine model

Bhattacharya

Pham

et al. 2014

Journal of Biomechanics

Self Cite

View full text Add to dashboard Cite

show abstract

“…79 A study from patients aged 72–91 years without cardiac disease confirmed the well‐known calcification concentrated along the annulus or chordal insertion regions, but remarkably minimal changes in leaflet mechanical properties. 80 Unlike the semilunar cardiac valves, age‐dependent biological changes in the mitral valve are not well understood.…”

Section: Mitral Valve Ageingmentioning

confidence: 99%

Mitral valve disease—morphology and mechanisms

Levine¹,

Hagège²,

Judge³

et al. 2015

Nat Rev Cardiol

319

254

View full text Add to dashboard Cite

Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but—even in adult life—remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular–ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

show abstract

“…For the PML, the average thickness values of the leaflet belly and edge were 1.31 mm and 1.57 mm respectively. The leaflet belly and edge regions were identified as previously described 24 .…”

Section: Patient and Methodsmentioning

confidence: 99%

“…The material properties of the MV apparatus were obtained from an age- and gender-matched cadaver heart, i.e., 69 year old patient, from our previously published studies of human MV leaflets 24 and chordae tendineae 27 material characterization. Figure 2 shows the stress-strain curves from an equibiaxial protocol of the AML and PML leaflets in both directions and of four chords (AB was assumed to be equivalent to PB).…”

Section: Patient and Methodsmentioning

confidence: 99%

Finite Element Analysis of Patient-Specific Mitral Valve with Mitral Regurgitation

Pham

Kong

Martin

et al. 2017

Cardiovasc Eng Tech

Self Cite

View full text Add to dashboard Cite

Functional mitral regurgitation (FMR) is a significant complication of left ventricular (LV) dysfunction and strongly associated with a poor prognosis. In this study, we developed a patient-specific finite element (FE) model of the mitral apparatus in a FMR patient which included: both leaflets with thickness, annulus, chordae tendineae, and chordae insertions on the leaflets and origins on the papillary muscles. The FE model incorporated human age- and gender- matched anisotropic hyperelastic material properties, and MV closure at systole was simulated. The model was validated by comparing the FE results from valve closure simulation with the in vivo geometry of the MV at systole. It was found that the FE model could not replicate the in vivo MV geometry without the application of tethering pre-tension force in the chordae at diastole. Upon applying the pre-tension force and performing model optimization by adjusting the chordal length, position, and leaflet length, a good agreement between the FE model and the in vivo model was established. Not only were the chordal forces high at both diastole and systole, but the tethering force on the anterior papillary muscle was higher than that of the posterior papillary muscle, which resulted in an asymmetrical gap with a larger orifice area at the anterolateral commissure resulting in MR. The analyses further show that high peak stress and strain were found at the chordal insertions where large chordal tethering forces were found. This study shows that the pre-tension tethering force plays an important role in accurately simulating the MV dynamics in this FMR patient, particularly in quantifying the degree of leaflet coaptation and stress distribution. Due to the complexity of the disease, the patient-specific computational modeling procedure of FMR patients presented should be further evaluated using a large patient cohort. However, this study provides useful insights into the MV biomechanics of a FMR patient, and could serve as a tool to assist in pre-operative planning for MV repair or replacement surgical or interventional procedures.

show abstract

Material properties of aged human mitral valve leaflets

Cited by 53 publications

References 74 publications

Tension to passively cinch the mitral annulus through coronary sinus access: An ex vivo study in ovine model

Tension to passively cinch the mitral annulus through coronary sinus access: An ex vivo study in ovine model

Mitral valve disease—morphology and mechanisms

Finite Element Analysis of Patient-Specific Mitral Valve with Mitral Regurgitation

Contact Info

Product

Resources

About