Validation of a Fluid-Structure Interaction Model for the Characterization of Transcatheter Mitral Valve Repair Devices

2021 ◽  
Vol 7 (2) ◽  
pp. 605-608
Author(s):  
Robert Ott ◽  
Alper Ö Öner ◽  
Paul Hermann Bellé ◽  
Finja Borowski ◽  
Klaus-Peter Schmitz ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Flow Conditions ◽  
Valve Repair ◽  
Structure Interaction ◽  
Device Implantation ◽  
Transcatheter Mitral Valve Repair ◽  
Vitro Data ◽  
In Vitro Data

Abstract Mitral regurgitation (MR) is the second most frequent indication for heart valve surgery and catheter interventions. According to European and US-American guidelines, transcatheter mitral valve repair in general and transcatheter edge-to-edge repair (TEER) in particular may be considered as a treatment option for selected high-risk patients. However, the biomechanical impact of TEERdevices on the mitral valve (MV) has not yet been fully understood. To address this problem, a 3D-Fluid-Structure Interaction (FSI) framework utilizing non-linear Finite Element Analysis (FEA) for the MV apparatus and Smoothed Particle Hydrodynamics (SPH) for the pulsatile fluid flow was developed and validated against in vitro data. An artificial MV-model (MVM) with a prolapse in the A2-P2 region and a custom-made TEER device implanted in the A2-P2 region were used for the in vitro investigations. In accordance with ISO 5910, projected mitral orifice areas (PMOA), flow rates as well as atrial and ventricular pressures were measured under pulsatile flow conditions before and after TEER device implantation. For the FSI-model, the MVM geometry was reconstructed by means of microcomputed tomography in a quasi-stress-free configuration. Quasi-static tensile test data was utilized for the development of linear- and hyperelastic material models of the chordae tendineae and leaflets, respectively. The fluid flow was modelled assuming an incompressible, homogenous Newtonian behaviour. Time-varying in vitro transmitral pressure loading was applied as a boundary condition. In vitro investigations show that TEER device implantation in the A2-P2 region effectively reduces the regurgitation fraction (RF) from 55 % to 13 %. Moreover, the comparison of experimental and numerical data yields a deviation of 2.09 % for the RF and a deviation of 0.40 % and 6.47 % for the maximum and minimum PMOA, respectively. The developed FSI-framework is in good agreement with in vitro data and is therefore applicable for the characterization of the biomechanical impact of different TEER devices under pulsatile flow conditions.

scholarly journals Intracardiac Visualization of Transcatheter Mitral Valve Repair in an In Vitro Passive Beating Heart

Circulation ◽  
2015 ◽  
Vol 132 (9) ◽  
Author(s):  
Guido Gelpi ◽  
Claudia Romagnoni ◽  
Riccardo Vismara ◽  
Andrea Mangini ◽  
Monica Contino ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Mitral Valve Repair ◽  
Beating Heart ◽  
Valve Repair ◽  
Transcatheter Mitral Valve Repair

scholarly journals Cardiac CT derived 3D reconstruction discriminates for complexity and hemodynamic effect of transcatheter mitral valve repair

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
F Meijerink ◽  
I Wolsink ◽  
M Holierook ◽  
E V Chekanova ◽  
R N Planken ◽  
...  
Keyword(s):  
Mitral Valve ◽  
3D Reconstruction ◽  
Mitral Valve Repair ◽  
Cardiac Ct ◽  
Mitral Annulus ◽  
Hemodynamic Effect ◽  
Valve Repair ◽  
Implantation Time ◽  
Device Implantation ◽  
Transcatheter Mitral Valve Repair

Abstract Background Transcatheter mitral valve repair (TMVR) is increasingly used to treat mitral regurgitation (MR) in high risk patients. Optimal transseptal access and guiding catheter position are essential to perform adequate repair. Anatomy of the inter-atrial septum (IAS) and mitral annulus (MA) are often complex and difficult to determine from echocardiography. Purpose The aim of the current study was to evaluate whether pre-TMVR cardiac CT and 3D reconstruction of the IAS and MA could discriminate for complexity and hemodynamic effect of TMVR. Methods Patients planned for TMVR, underwent cardiac CT scan (if eligible). Post-processing software was used to segment and reconstruct the aortic root, IAS, fossa ovalis (FO) and MA, resulting in a 3D model. The following parameters were measured in each model: (1) IAS angle (°) (2) Posterior-FO angle (°) (3) FO-perpendicularity angle (°) (4) MA area (cm2). Patient specific anatomy was categorized in 4 groups as either (1) Posterior-perpendicular (PP) FO + limited IAS angle, (2) PP FO + wide IAS angle, (3) non-PP FO + limited IAS angle or (4) non-PP FO + wide IAS angle. PP FO was defined as posterior-FO angle >65° and FO-perpendicularity angle >135°. IAS angle was considered limited if <110°. Device implantation time (min) was used to assess complexity of the procedure and was compared between the different groups. MR reduction (grades), number of clips used and mitral valve (MV) gradient (mmHg) were compared for patients with MA area <14 cm2 vs. ≥14 cm2. Results 46 patients (mean age 75 years, 41% male) were included. Anatomy was classified (1) PP FO + limited IAS angle in 13, (2) PP FO + wide IAS angle in 13, (3) Non-PP FO + limited IAS angle in 8 and (4) Non-PP FO + wide IAS angle in 12. Median device implantation time was 20 min in group 1, compared to 39 min in group 2 (p=0.02), 33 min in group 3 (p=0.03) and 29 min in group 4 (p=0.08). In patients with MA area <14 cm2, MR reduction was greater (2.22 vs. 1.68, p=0.02), number of clips used was lower (1.44 vs. 1.79, p=0.05) and MV gradient was higher, though not significant (3.15 vs. 2.58, p=0.26) Conclusion The current study showed that TMVR seemed less complex in patients with an optimal anatomy. In patients with limited mitral annulus area a more favorable hemodynamic effect was achieved. Cardiac CT and 3D reconstruction could therefore be of strong aid for procedural planning of TMVR. FUNDunding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Abbott Vascular Anatomy and device implantation time Hemodynamic effect of annulus area

Use of Toxicokinetics in Risk Assessment Based on In Vitro Data

1993 ◽  
Vol 21 (2) ◽  
pp. 173-180
Author(s):  
Gunnar Johanson
Keyword(s):  
Risk Assessment ◽  
Whole Body ◽  
External Exposure ◽  
Target Dose ◽  
Toxic Response ◽  
Route Of Exposure ◽  
Vitro Data ◽  
In Vitro Data

This presentation addresses some aspects of the methodology, advantages and problems associated with toxicokinetic modelling based on in vitro data. By using toxicokinetic models, particularly physiologically-based ones, it is possible, in principle, to describe whole body toxicokinetics, target doses and toxic effects from in vitro data. Modelling can be divided into three major steps: 1) to relate external exposure (applied dose) of xenobiotic to target dose; 2) to establish the relationship between target dose and effect (in vitro data, e.g. metabolism in microsomes, partitioning in tissue homogenates, and toxicity in cell cultures, are useful in both steps); and 3) to relate external exposure to toxic effect by combining the first two steps. Extrapolations from in vitro to in vivo, between animal and man, and between high and low doses, can easily be carried out by toxicokinetic simulations. In addition, several factors that may affect the toxic response by changing the target dose, such as route of exposure and physical activity, can be studied. New insights concerning the processes involved in toxicity often emerge during the design, refinement and validation of the model. The modelling approach is illustrated by two examples: 1) the carcinogenicity of 1,3-butadiene; and 2) the haematotoxicity of 2-butoxyethanol. Toxicokinetic modelling is an important tool in toxicological risk assessment based on in vitro data. Many factors, some of which can, and should be, studied in vitro, are involved in the expression of toxicity. Successful modelling depends on the identification and quantification of these factors.

scholarly journals Lymphocutaneous spread of Mycobacterium elephantis in an immunocompetent individual: A case report

2021 ◽  
Vol 9 ◽  
pp. 2050313X2110349
Author(s):  
Brett D Edwards ◽  
Ranjani Somayaji ◽  
Dina Fisher ◽  
Justin C Chia
Keyword(s):  
Case Report ◽  
Chronic Lung Disease ◽  
Contaminated Soil ◽  
Lung Abscess ◽  
Immunocompetent Individual ◽  
First Case ◽  
Antimycobacterial Agents ◽  
Vitro Data ◽  
In Vitro Data

Mycobacterium elephantis was first described when isolated from an elephant that succumbed to lung abscess. However, despite this namesake, it is not associated with animals and has been described most often as a probable colonizer rather than pathogen in humans with chronic lung disease. In this report, we describe the first case of lymphocutaneous infection from M. elephantis, likely as a result of cutaneous inoculation with contaminated soil. This offers further evidence to its capabilities as a pathogen. We provide a review of the limited prior reports of M. elephantis and outline the available in vitro data on efficacy of various antimycobacterial agents.

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