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Examples of correctly matched chordae with inaccuracies: a. Slight inaccuracy (GED rel = 0.17), data3. b. More pronounced inaccuracy (GED rel = 0.33), data1. c. Important parts missing (GED rel = 0.46), data5. d. Inaccurate topology (GED rel = 0.7), data4. e. Inaccurate topology (GED rel = 0.57), data1.
Source publication
PurposeMitral valve computational models are widely studied in the literature. They can be used for preoperative planning or anatomical understanding. Manual extraction of the valve geometry on medical images is tedious and requires special training, while automatic segmentation is still an open problem.Methods
We propose here a fully automatic pip...
Citations
... Various works have studied MV behavior without including fluid mechanics [1,2], but they only focus on peak systole at the static state. Their aim is not to examine the complex dynamic motion nor to simulate blood leakage through the valve. ...
Purpose:
Realistic fluid-structure interaction (FSI) simulation of the mitral valve opens the way toward planning for surgical repair. In the literature, blood leakage is identified by measuring the flow rate, but detailed information about closure efficiency is missing. We present in this paper an FSI model that improves the detection of blood leakage by building a map of contact.
Methods:
Our model is based on the immersed boundary method that captures a map of contact and perfect closure of the mitral valve, without the presence of orifice holes, which often appear with existing methods. We also identified important factors influencing convergence issues.
Results:
The method is demonstrated in three typical clinical situations: mitral valve with leakage, bulging, and healthy. In addition to the classical ways of evaluating MV closure, such as stress distribution and flow rate, the contact map provides easy detection of leakage with identification of the sources of leakage and a quality assessment of the closure.
Conclusions:
Our method significantly improves the quality of the simulation and allows the identification of regurgitation as well as a spatial evaluation of the quality of valve closure. Comparably fast simulation, ability to simulate large deformation, and capturing detailed contact are the main aspects of the study.
... chordae tendineae, is modeled. The inclusion of the chordae into the MV model could however be necessary for biomechanical studies (64) or realization of a 3D MV movement using fully-coupled FSI (55). Yet, it is to note, that Morud et al. (65) found a negligible impact of chordae on the systolic intraventricular flow. ...
Background: Cardiac CT (CCT) is well suited for a detailed analysis of heart structures due to its high spatial resolution, but in contrast to MRI and echocardiography, CCT does not allow an assessment of intracardiac flow. Computational fluid dynamics (CFD) can complement this shortcoming. It enables the computation of hemodynamics at a high spatio-temporal resolution based on medical images. The aim of this proposed study is to establish a CCT-based CFD methodology for the analysis of left ventricle (LV) hemodynamics and to assess the usability of the computational framework for clinical practice.
Materials and Methods: The methodology is demonstrated by means of four cases selected from a cohort of 125 multiphase CCT examinations of heart failure patients. These cases represent subcohorts of patients with and without LV aneurysm and with severe and no mitral regurgitation (MR). All selected LVs are dilated and characterized by a reduced ejection fraction (EF). End-diastolic and end-systolic image data was used to reconstruct LV geometries with 2D valves as well as the ventricular movement. The intraventricular hemodynamics were computed with a prescribed-motion CFD approach and evaluated in terms of large-scale flow patterns, energetic behavior, and intraventricular washout.
Results: In the MR patients, a disrupted E-wave jet, a fragmentary diastolic vortex formation and an increased specific energy dissipation in systole are observed. In all cases, regions with an impaired washout are visible. The results furthermore indicate that considering several cycles might provide a more detailed view of the washout process. The pre-processing times and computational expenses are in reach of clinical feasibility. Conclusion: The proposed CCT-based CFD method allows to compute patient-specific intraventricular hemodynamics and thus complements the informative value of CCT. The method can be applied to any CCT data of common quality and represents a fair balance Obermeier et al. CT-Based Heart Hemodynamics between model accuracy and overall expenses. With further model enhancements, the computational framework has the potential to be embedded in clinical routine workflows, to support clinical decision making and treatment planning.
... Recent excellent studies have revealed diverse advancement in computational MV modeling, more specifically in terms of modeling of the chordae tendineae [13][14][15][16]. Moreover, solid mechanical evaluation of the chordae tissue and improved mathematical modeling of the chordae tendineae [17][18][19][20][21] as well as experimental and computational blood flow studies with respect to the chordae structure [22][23][24] have revealed the importance of chordae tendineae studies. ...
The strut chordae (SC) have a unique structure and play an important role in reinforcing the tunnel-shaped configuration of the mitral valve (MV) at the inflow and outflow tracts. We investigated the effect of varying the SC insertion location on normal MV function and dynamics to better understand the complex MV structures. A virtual parametric MV model was designed to replicate a normal human MV, and a total of nine MV modes were created from combinations of apical and lateral displacements of the SC insertion location. MV function throughout the full cardiac cycle was simulated using dynamic finite element analysis for all MV models. While the leaflet stress distribution and coaptation showed similar patterns in all nine MV models, the maximum leaflet stress values increased in proportion to the width of the SC insertion locations. A narrower SC insertion location resulted in a longer coaptation length and a smaller anterior coaptation angle. The top-narrow MV model demonstrated the shortest anterior leaflet bulging distance, lower stresses across the anterior leaflet, and the lowest maximum stresses. This biomechanical evaluation strategy can help us better understand the effect of the SC insertion locations on mechanism, function, and pathophysiology of the MV.
The dynamic behavior of the mitral valve (MV) is highly influenced by the material model used to describe the leaflet motion. Due to the presence of collagen fibers, MV leaflets show an anisotropic behavior. The aim of this study is to investigate the influence of anisotropy on the fluid-structure interaction (FSI) simulation of the MV dynamic closure. The FSI simulation of the MV is performed using an immersed boundary method. Two constitutive models, Holzapfel-Gasser-Ogden for the anisotropic, and third-order Ogden for the isotropic are used. For the anisotropic model, two fiber directions, one that is parallel to the annulus surface and another that follows an arc on the leaflets are considered. In order to take into account the effects of both the chordae structure and leaflet geometry, generic and image-based MV are studied. The quality of the closure is evaluated based on measuring the bulging area, contact map, and flow rate. In both generic and image-based, a significant difference is observed between the anisotropic and isotropic cases. Additionally, the chordae forces during the closure are compared with ex-vivo data of the literature and show good similarities with these results.KeywordsMitral valveFluid-structure interactionanisotropy
