Shape Optimization of a Self-deployable Anchor Designed for Percutaneous Mitral Valve Repair

2012 ◽  
Vol 6 (1) ◽  
Author(s):  
Farhad Javid ◽  
Jorge Angeles ◽  
Damiano Pasini ◽  
Renzo Cecere
Keyword(s):  
Stress Concentration ◽  
Mitral Valve ◽  
Stress Distribution ◽  
Iterative Process ◽  
Von Mises Stress ◽  
Valve Repair ◽  
Percutaneous Mitral Valve Repair ◽  
Von Mises ◽  
Previous Iteration ◽  
Weight Coefficients

A new percutaneous annuloplasty technique for mitral regurgitation is proposed here. In this technique, inter-related anchors are first inserted around the annulus via a trans-septal catheter. The tethered wire passed through the anchors is then pulled to shrink the annulus and stop regurgitation. The anchors should withstand large deformation, applied during the delivery process, and should recover their original shape after being released inside the tissue. The shape of the anchors is, thus, optimized in an iterative process, to avoid stress concentration by minimizing the weighted rms value of the curvature along the anchor. The weight coefficients in each iteration are defined based on the stress distribution of the anchor obtained in the previous iteration. The procedure finally results in a structurally optimum anchor with a minimum in the maximum von Mises stress. This anchor is fabricated from Nitinol and tested in a cadaveric swine heart.

scholarly journals The Effect of Framework Design on Stress Distribution in Implant-Supported FPDs: A 3-D FEM Study

2010 ◽  
Vol 04 (04) ◽  
pp. 374-382 ◽  
Author(s):  
Oguz Eraslan ◽  
Ozgur Inan ◽  
Asli Secilmis
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Bone Structure ◽  
Von Mises Stress ◽  
Stress Concentrations ◽  
Biomechanical Behavior ◽  
Framework Design ◽  
Occlusal Surfaces ◽  
Von Mises

Objectives: The biomechanical behavior of the superstructure plays an important role in the functional longevity of dental implants. However, information about the influence of framework design on stresses transmitted to the implants and supporting tissues is limited. The purpose of this study was to evaluate the effects of framework designs on stress distribution at the supporting bone and supporting implants.Methods: In this study, the three-dimensional (3D) finite element stress analysis method was used. Three types of 3D mathematical models simulating three different framework designs for implant- supported 3-unit posterior fixed partial dentures were prepared with supporting structures. Convex (1), concave (2), and conventional (3) pontic framework designs were simulated. A 300-N static vertical occlusal load was applied on the node at the center of occlusal surface of the pontic to calculate the stress distributions. As a second condition, frameworks were directly loaded to evaluate the effect of the framework design clearly. The Solidworks/Cosmosworks structural analysis programs were used for finite element modeling/analysis.Results: The analysis of the von Mises stress values revealed that maximum stress concentrations were located at the loading areas for all models. The pontic side marginal edges of restorations and the necks of implants were other stress concentration regions. There was no clear difference among models when the restorations were loaded at occlusal surfaces. When the veneering porcelain was removed, and load was applied directly to the framework, there was a clear increase in stress concentration with a concave design on supporting implants and bone structure.Conclusions: The present study showed that the use of a concave design in the pontic frameworks of fixed partial dentures increases the von Mises stress levels on implant abutments and supporting bone structure. However, the veneering porcelain element reduces the effect of the framework and compensates for design weaknesses. (Eur J Dent 2010;4:374-382)

Dynamic Visualization of Stress Distribution by Mechanoluminescence Image

2008 ◽  
Vol 388 ◽  
pp. 265-268 ◽  
Author(s):  
Chen Shu Li ◽  
Chao Nan Xu ◽  
Lin Zhang ◽  
Hiroshi Yamada ◽  
Yusuke Imai ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Stress Distribution ◽  
Theoretical Calculation ◽  
Real Time ◽  
Metal Surface ◽  
Test Object ◽  
Small Deformation ◽  
Von Mises Stress ◽  
Dynamic Visualization ◽  
Von Mises

Dynamic visualization of stress distribution even due to a small deformation has been realized by coating the surface of the test object of metal with a upgrade mechanoluminescence (ML) material of SrAl2O4:Eu (SAO). In this paper we report the application of this ML sensing technique to stress concentration analysis on an aluminium plate. And the comparison with a theoretical calculation demonstrated that the ML intensity of SAO sensing film correlates linearly with von Mises stress on metal surface and the observed real-time ML images quantitatively reflect stress concentration.

Optimum Design of an Anchoring System for Percutaneous Mitral Valve Repair

2010 ◽  
Author(s):  
Farhad Javid ◽  
Jorge Angeles ◽  
Damiano Pasini ◽  
Renzo Cecere
Keyword(s):  
Mitral Valve ◽  
Shape Optimization ◽  
Mitral Valve Repair ◽  
Heart Tissue ◽  
Optimum Shape ◽  
Valve Repair ◽  
Percutaneous Mitral Valve Repair ◽  
Anchoring System ◽  
Von Mises ◽  
Von Mises Stresses

In a novel procedure for percutaneous mitral valve repair, inter-related hook-shaped anchors are inserted around the annulus to replace the surgeon’s suturing in open-heart ring annuloplasty. To properly attach to the tissue, the anchors should withstand large deformation applied during the delivery process and recover their original shape when released into the heart tissue. To this end, stress concentration is avoided along the anchors, which are fabricated of a super-elastic material, by means of shape optimization. Shape optimization consists in finding the smoothest anchor mid-curve possible, which minimizes the von Mises stresses applied during the delivery process. An optimization algorithm aimed at minimizing the weighted rms value of the curvature is introduced. A geometrically optimum shape is obtained by equally weighting the curvature values. Further reduction in the stress values is possible by weighting the curvature values along the anchor in an iterative procedure that yields a structurally optimum anchor. The weights at each iteration are defined proportional to the stress distribution along the anchor obtained in the previous iteration.

Thermal Stress Induced Void Formation in Semiconductor Interconnect

2002 ◽  
Author(s):  
Xiaoling He ◽  
Clemens Burda
Keyword(s):  
Thermal Stress ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Strain Distribution ◽  
Void Formation ◽  
Von Mises Stress ◽  
Stress Strain ◽  
Von Mises ◽  
Low K ◽  
Common Defect

Stress voiding is a common defect of the semiconductor interconnect. In thermal cycles, other defects such as the hillocks, delamination can also occur. For the Cu/low-k interconnect, simulation with Ansys is made to analysis the interconnect stress-strain distribution and deformation. Results indicate that stress induced void is prone to form in the via than in the metal lines. Flower defect appear at the via top can also be analyzed based on the stress distribution. It is found that Von-Mises stress represent the localization of the stress concentration, which cause delamination and over-stress failure at the interface of the different materials.

scholarly journals Finite Element Analysis of Stress in Bone and Abutment-Implant Interface under Static and Cyclic Loadings

2020 ◽  
Author(s):  
Saeed Nokar ◽  
Hamid Jalali ◽  
Farideh Nozari ◽  
Mahnaz Arshad
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Maximum Stress ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Bone Implant ◽  
Factors Affecting ◽  
Von Mises

Objectives: The success of implant treatment depends on many factors affecting the bone-implant, implant-abutment, and abutment-prosthesis interfaces. Stress distribution in bone plays a major role in success/failure of dental implants. This study aimed to assess the pattern of stress distribution in bone and abutment-implant interface under static and cyclic loadings using finite element analysis (FEA). Materials and Methods: In this study, ITI implants (4.1×12 mm) placed at the second premolar site with Synocta abutments and metal-ceramic crowns were simulated using SolidWorks 2007 and ABAQUS software. The bone-implant contact was assumed to be 100%. The abutments were tightened with 35 Ncm preload torque according to the manufacturer’s instructions. Static and cyclic loads were applied in axial (116 Ncm), lingual (18 Ncm), and mesiodistal (24 Ncm) directions. The maximum von Mises stress and strain values ​​were recorded. Results: The maximum stress concentration was at the abutment neck during both static and cyclic loadings. Also, maximum stress concentration was observed in the cortical bone. The loading stress was higher in cyclic than static loading. Conclusion: Within the limitations of this study, it can be concluded that the level of stress in single-unit implant restorations is within the tolerable range by bone.

scholarly journals Favorable course of tricuspid regurgitation after percutaneous mitral valve repair is associated with improved survival and clinical outcome

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
F Meijerink ◽  
J Baan ◽  
B.J Bouma
Keyword(s):  
Mitral Valve ◽  
Clinical Outcome ◽  
Mitral Valve Repair ◽  
Tricuspid Regurgitation ◽  
Nyha Class ◽  
Funding Source ◽  
Valve Repair ◽  
Percutaneous Mitral Valve Repair ◽  
All Cause Mortality

Abstract Background Tricuspid Regurgitation (TR) is often present in patients with mitral regurgitation (MR) and is associated with increased mortality and morbidity after percutaneous mitral valve repair (PMVR) using the MitraClip (Abbott Vascular). It is unclear to what extent TR is reduced after PMVR and whether the reduction of TR is related to survival and functional outcome. Purpose The aim of this study was to determine (1) the TR course after PMVR and (2) if this was related to survival and clinical outcome. Methods Patients who underwent PMVR and had complete echocardiographic data at baseline and follow-up were included. TR severity was graded as none, mild, moderate or severe (according to current guidelines) and was determined before treatment and at 6-months of follow up. Favorable TR course was defined as improvement of ≥1 grade or ≤ mild TR at 6-months. Clinical endpoints were all-cause mortality during 1-year of follow-up and improvement in New York Heart Association (NYHA) functional class after 6 months. Results A total of 67 patients were included (mean age 76 years, 57% male, 81% NYHA class ≥3 and 69% baseline TR ≥ moderate). Favorable TR course was achieved in 31 patients (46%) (figure 1A). All-cause mortality at 1 year was 7.5%, and was lower in the favorable TR course group (0% vs. 13.9%, p=0.057) (figure 1B). Improvement in NYHA class at 6-months was seen in 45% of patients without vs. 81% of patients with favorable TR course (p=0.01) (figure 1C). Conclusion A favorable TR course is achieved in 46% of PMVR patients and is associated with improved survival and improvement of NYHA class. The relatively high rate of an unfavorable TR course at 6-months, indicates that interventional treatment of the tricuspid valve might benefit these patients. TR course (A) and NYHA improvement (B) Funding Acknowledgement Type of funding source: Other. Main funding source(s): Abbott

Percutaneous Mitral Valve Repair Vs. Stand-Alone Medical Therapy in Patients with Functional Mitral Regurgitation and Heart Failure

2020 ◽  
Vol 21 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Tomás Benito-González ◽  
Rodrigo Estévez-Loureiro ◽  
Pedro A. Villablanca ◽  
Patrizio Armeni ◽  
Ignacio Iglesias-Gárriz ◽  
...  
Keyword(s):  
Heart Failure ◽  
Mitral Valve ◽  
Mitral Regurgitation ◽  
Mitral Valve Repair ◽  
Medical Therapy ◽  
Functional Mitral Regurgitation ◽  
Valve Repair ◽  
Percutaneous Mitral Valve Repair

Percutaneous Mitral Valve Repair in Patients with Prior Cardiac Surgery

2012 ◽  
Vol 27 (3) ◽  
pp. 295-298 ◽  
Author(s):  
Salvatore Scandura ◽  
Gian Paolo Ussia ◽  
Anna Caggegi ◽  
Sarah Mangiafico ◽  
Valeria Cammalleri ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Mitral Valve ◽  
Mitral Valve Repair ◽  
Valve Repair ◽  
Percutaneous Mitral Valve Repair
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