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Yin Z, Armour C, Kandail H, O'Regan DP, Bahrami T, Mirsadraee S, Pirola S, Xu XY. Fluid-structure interaction analysis of a healthy aortic valve and its surrounding haemodynamics. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2024; 40:e3865. [PMID: 39209425 DOI: 10.1002/cnm.3865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 07/23/2024] [Accepted: 08/17/2024] [Indexed: 09/04/2024]
Abstract
The opening and closing dynamics of the aortic valve (AV) has a strong influence on haemodynamics in the aortic root, and both play a pivotal role in maintaining normal physiological functions of the valve. The aim of this study was to establish a subject-specific fluid-structure interaction (FSI) workflow capable of simulating the motion of a tricuspid healthy valve and the surrounding haemodynamics under physiologically realistic conditions. A subject-specific aortic root was reconstructed from magnetic resonance (MR) images acquired from a healthy volunteer, whilst the valve leaflets were built using a parametric model fitted to the subject-specific aortic root geometry. The material behaviour of the leaflets was described using the isotropic hyperelastic Ogden model, and subject-specific boundary conditions were derived from 4D-flow MR imaging (4D-MRI). Strongly coupled FSI simulations were performed using a finite volume-based boundary conforming method implemented in FlowVision. Our FSI model was able to simulate the opening and closing of the AV throughout the entire cardiac cycle. Comparisons of simulation results with 4D-MRI showed a good agreement in key haemodynamic parameters, with stroke volume differing by 7.5% and the maximum jet velocity differing by less than 1%. Detailed analysis of wall shear stress (WSS) on the leaflets revealed much higher WSS on the ventricular side than the aortic side and different spatial patterns amongst the three leaflets.
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Affiliation(s)
- Zhongjie Yin
- Department of Chemical Engineering, Imperial College London, London, UK
| | - Chlöe Armour
- Department of Chemical Engineering, Imperial College London, London, UK
- National Heart and Lung Institute, Imperial College London, London, UK
| | | | - Declan P O'Regan
- Laboratory of Medical Sciences, Imperial College London, London, UK
| | - Toufan Bahrami
- National Heart and Lung Institute, Imperial College London, London, UK
- Department of Cardiothoracic Surgery, Royal Brompton and Harefield Hospitals NHS Trust, London, UK
| | - Saeed Mirsadraee
- National Heart and Lung Institute, Imperial College London, London, UK
- Department of Radiology, Royal Brompton and Harefield Hospitals NHS Trust, London, UK
| | - Selene Pirola
- Department of Chemical Engineering, Imperial College London, London, UK
- Department of BioMechanical Engineering, TU Delft, Delft, The Netherlands
| | - Xiao Yun Xu
- Department of Chemical Engineering, Imperial College London, London, UK
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Hwang YS, Kim TK, Yang DJ, Jang SH, Lee DW. Complicated calcified alloplastic implants in the nasal dorsum: A clinical analysis. World J Clin Cases 2024; 12:3351-3359. [PMID: 38983394 PMCID: PMC11229894 DOI: 10.12998/wjcc.v12.i18.3351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 04/12/2024] [Accepted: 05/09/2024] [Indexed: 06/13/2024] Open
Abstract
BACKGROUND In rhinoplasty, calcification around silicone implants is frequently observed in the tip dorsum (TD) area. Additionally, based on a review of various literature, it is presumed that calcification in silicone implants occurs due to both inflammatory chemical reactions and physical friction against the tissue. The calcification of nasal silicone implants not only results in the functional loss of the implants, but also leads to material deformation. However, there is a lack of research on calcification of nasal silicone implants in the current literature. AIM To elucidate various clinical characteristics of calcification around nasal silicone implants, using histological and radiological analysis. METHODS This study analyzed data from 16 patients of calcified nasal implants, who underwent revision rhinoplasty for various reasons after undergoing augmentation rhinoplasty with silicone implants. The collected data included information on implant duration, implant types, location of calcification, presence of inflammatory reactions, and computed tomography (CT) scans. RESULTS The most common location of calcification, as visually analyzed, was in the TD area, accounting for 56%. Additionally, the analysis of CT scans revealed a trend of increasing Hounsfield Unit values for calcification with the duration of implantation, although this trend was not statistically significant (P = 0.139). CONCLUSION Our study shows that reducing the frequency of calcification may be achievable by using softer silicone implants and by minimizing the damage to perioperative tissues.
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Affiliation(s)
- Yong-Seon Hwang
- Department of Plastic and Reconstructive Surgery, College of Medicine, Soonchunhyang University, Cheonan-Si 31151, South Korea
| | - Taek-Kyun Kim
- Department of Plastic Surgery, The PLUS Plastic Surgery Clinic, Seoul 06035, South Korea
| | - Dong-Jun Yang
- Department of Plastic Surgery, CDU Plastic Surgery Clinic, Seoul 06067, South Korea
| | - Si-Hyong Jang
- Department of Pathology, College of Medicine, Soonchunhyang University, Cheonan 31151, Chungcheongnam-do, South Korea
| | - Da-Woon Lee
- Department of Plastic and Reconstructive Surgery, College of Medicine, Soonchunhyang University, Cheonan-Si 31151, South Korea
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Weich H, Botes L, Doubell A, Jordaan J, Lewies A, Marimuthu P, van den Heever J, Smit F. Development and testing of a transcatheter heart valve with reduced calcification potential. Front Cardiovasc Med 2023; 10:1270496. [PMID: 38124891 PMCID: PMC10731034 DOI: 10.3389/fcvm.2023.1270496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 11/03/2023] [Indexed: 12/23/2023] Open
Abstract
Introduction Patients from developing countries who require heart valve surgery are younger and have less access to open heart surgery than those from developed countries. Transcatheter heart valves (THVs) may be an alternative but are currently unsuitable for young patients because of their inadequate durability. We developed and tested a THV utilizing two new types of decellularized bovine pericardial leaflets in an ovine model. Methods The two decellularized tissues [one with a very low dose (0.05%) of monomeric glutaraldehyde (GA) fixation and detoxification (DF) and the other without glutaraldehyde (DE)] were compared to an industry standard [Glycar-fixed with the standard dose (0.625%) of glutaraldehyde]. THVs were manufactured with the three tissue types and implanted in the pulmonary position of nine juvenile sheep for 180 days. Baseline and post-explantation evaluations were performed to determine the hemodynamic performance of the valves and their dynamic strength, structure, biological interaction, and calcification. Results Heart failure occurred in one animal due to incompetence of its Glycar valve, and the animal was euthanized at 158 days. The gradients over the Glycar valves were higher at the explant than at the implant, but the DE and DF valves maintained normal hemodynamic performance throughout the study. The DF and DE tissues performed well during the mechanical testing of explanted leaflets. Glycar tissue developed thick pannus and calcification. Compared to Glycar, the DF tissue exhibited reduced pannus overgrowth and calcification and the DE tissue exhibited no pannus formation and calcification. All tissues were endothelialized adequately. There was a striking absence of host ingrowth in the DE tissue leaflets, yet these leaflets maintained integrity and mechanical function. Conclusion In the juvenile sheep THV model, Glycar tissue developed significant pannus, calcification, and hemodynamic deterioration. Using a very low dose of monomeric GA to fix the decellularized bovine pericardium yielded less pannus formation, less calcification, and better hemodynamic function. We postulate that the limited pannus formation in the DF group results from GA. Bovine pericardium decellularized with our proprietary method resulted in inert tissue, which is a unique finding. These results justify further development and evaluation of the two decellularized tissue types in THVs for use in younger patients.
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Affiliation(s)
- Hellmuth Weich
- Division of Cardiology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Lezelle Botes
- Department of Health Sciences, Central University of Technology, Bloemfontein, South Africa
| | - Anton Doubell
- Division of Cardiology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Johan Jordaan
- Department of Cardiothoracic Surgery, Robert W.M. Frater Cardiovascular Research Centre, University of the Free State, Bloemfontein, South Africa
| | - Angelique Lewies
- Department of Cardiothoracic Surgery, Robert W.M. Frater Cardiovascular Research Centre, University of the Free State, Bloemfontein, South Africa
| | - Prennie Marimuthu
- Department of Cardiothoracic Surgery, Robert W.M. Frater Cardiovascular Research Centre, University of the Free State, Bloemfontein, South Africa
| | - Johannes van den Heever
- Department of Cardiothoracic Surgery, Robert W.M. Frater Cardiovascular Research Centre, University of the Free State, Bloemfontein, South Africa
| | - Francis Smit
- Department of Cardiothoracic Surgery, Robert W.M. Frater Cardiovascular Research Centre, University of the Free State, Bloemfontein, South Africa
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Weich H, Herbst P, Smit F, Doubell A. Transcatheter heart valve interventions for patients with rheumatic heart disease. Front Cardiovasc Med 2023; 10:1234165. [PMID: 37771665 PMCID: PMC10525355 DOI: 10.3389/fcvm.2023.1234165] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 08/28/2023] [Indexed: 09/30/2023] Open
Abstract
Rheumatic heart disease [RHD] is the most prevalent cause of valvular heart disease in the world, outstripping degenerative aortic stenosis numbers fourfold. Despite this, global resources are firmly aimed at improving the management of degenerative disease. Reasons remain complex and include lack of resources, expertise, and overall access to valve interventions in developing nations, where RHD is most prevalent. Is it time to consider less invasive alternatives to conventional valve surgery? Several anatomical and pathological differences exist between degenerative and rheumatic valves, including percutaneous valve landing zones. These are poorly documented and may require dedicated solutions when considering percutaneous intervention. Percutaneous balloon mitral valvuloplasty (PBMV) is the treatment of choice for severe mitral stenosis (MS) but is reserved for patients with suitable valve anatomy without significant mitral regurgitation (MR), the commonest lesion in RHD. Valvuloplasty also rarely offers a durable solution for patients with rheumatic aortic stenosis (AS) or aortic regurgitation (AR). MR and AR pose unique challenges to successful transcatheter valve implantation as landing zone calcification, so central in docking transcatheter aortic valves in degenerative AS, is often lacking. Surgery in young RHD patients requires mechanical prostheses for durability but morbidity and mortality from both thrombotic complications and bleeding on Warfarin remains excessively high. Also, redo surgery rates are high for progression of aortic valve disease in patients with prior mitral valve replacement (MVR). Transcatheter treatments may offer a solution to anticoagulation problems and address reoperation in patients with prior MVR or failing ventricles, but would have to be tailored to the rheumatic environment. The high prevalence of MR and AR, lack of calcification and other unique anatomical challenges remain. Improvements in tissue durability, the development of novel synthetic valve leaflet materials, dedicated delivery systems and docking stations or anchoring systems to securely land the transcatheter devices, would all require attention. We review the epidemiology of RHD and discuss anatomical differences between rheumatic valves and other pathologies with a view to transcatheter solutions. The shortcomings of current RHD management, including current transcatheter treatments, will be discussed and finally we look at future developments in the field.
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Affiliation(s)
- Hellmuth Weich
- Division of Cardiology, Department of Medicine, Faculty of Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Philip Herbst
- Division of Cardiology, Department of Medicine, Faculty of Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Francis Smit
- Robert W.M. Frater Cardiovascular Research Centre, University of the Free State, Bloemfontein, South Africa
| | - Anton Doubell
- Division of Cardiology, Department of Medicine, Faculty of Health Sciences, Stellenbosch University, Cape Town, South Africa
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The effect of fundamental curves on geometric orifice and coaptation areas of polymeric heart valves. J Mech Behav Biomed Mater 2020; 112:104039. [DOI: 10.1016/j.jmbbm.2020.104039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 08/04/2020] [Accepted: 08/12/2020] [Indexed: 12/29/2022]
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Tasca G, Fiore GB, Mangini A, Romagnoni C, Gamba A, Redaelli A, Antona C, Vismara R. Opening–closing pattern of four pericardial prostheses: results from an in vitro study of leaflet kinematics. J Artif Organs 2016; 19:350-356. [DOI: 10.1007/s10047-016-0910-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 05/13/2016] [Indexed: 10/21/2022]
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Xie D, Leng Y, Jing F, Huang N. A brief review of bio-tribology in cardiovascular devices. BIOSURFACE AND BIOTRIBOLOGY 2015. [DOI: 10.1016/j.bsbt.2015.11.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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