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D'Souza GA, Rinaldi JE, Meki M, Crusan A, Richardson E, Shinnar M, Herbertson LH. Using a Mock Circulatory Loop as a Regulatory Science Tool to Simulate Different Heart Failure Conditions. J Biomech Eng 2024; 146:011004. [PMID: 37831143 DOI: 10.1115/1.4063746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 10/06/2023] [Indexed: 10/14/2023]
Abstract
Mechanical circulatory support (MCS) device therapy is one of the primary treatment options for end-stage heart failure (HF), whereby a mechanical pump is integrated with the failing heart to maintain adequate tissue perfusion. The ISO 14708-5:2020 standard prescribes generic guidelines for nonclinical device evaluation and system performance testing of MCS devices using a mock circulatory loop (MCL). However, the utility of MCLs in premarket regulatory submissions of MCS devices is ambiguous, and the specific disease states that the device is intended to treat are not usually simulated. Hence, we aim to outline the potential of MCLs as a valuable regulatory science tool for characterizing MCS device systems by adequately representing target clinical-use HF conditions on the bench. Target pathophysiologic hemodynamics of HF conditions (i.e., cardiogenic shock (CS), left ventricular (LV) hypertrophy secondary to hypertension, and coronary artery disease), along with a healthy adult at rest and a healthy adult during exercise are provided as recommended test conditions. The conditions are characterized based on LV, aorta, and left atrium pressures using recommended cardiac hemodynamic indices such as systolic, diastolic, and mean arterial pressure, mean cardiac output (CO), cardiac cycle time, and systemic vascular resistance. This study is a first step toward standardizing MCLs to generate well-defined target HF conditions used to evaluate MCS devices.
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Affiliation(s)
- Gavin A D'Souza
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993
| | - Jean E Rinaldi
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993
| | - Moustafa Meki
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993
| | - Annabelle Crusan
- Circulatory Support Devices Team, Office of Product Evaluation and Quality, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993
| | - Eric Richardson
- Circulatory Support Devices Team, Office of Product Evaluation and Quality, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993
| | - Meir Shinnar
- Circulatory Support Devices Team, Office of Product Evaluation and Quality, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993
| | - Luke H Herbertson
- Division of Applied Mechanics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993
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2
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Jin C, Zhao L, Wu Z, Li B, Liu R, He H, Wang L, Wang W. Comparison on the properties of bovine pericardium and porcine pericardium used as leaflet materials of transcatheter heart valve. Artif Organs 2021; 46:427-438. [PMID: 34545589 DOI: 10.1111/aor.14074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/06/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND In order to obtain the smaller delivery diameter, porcine pericardium had been used as a substitute material of bovine pericardium for the leaflet materials of transcatheter heart valve (THV). However, the differences between them had not been fully studied. Therefore, this study compared the microstructure, biochemical and mechanical properties of two materials and hydrodynamics of THV made by the two materials in detail. METHODS In this study, firstly, the microstructure of pericardium was analyzed by staining and scanning electron microscope; secondly, the biochemical properties of pericardium after different processes were compared by heat shrinkage temperature test, free amino and carboxyl concentration test, enzyme degradation test, subcutaneous implantation calcification analysis in rats; finally, the mechanical properties were evaluated by uniaxial tensile test before and after the pericardium being crimped, and then, the hydrodynamics of THV was studied according to the ISO5840 standard. RESULTS Compared with bovine pericardium, after the same process, porcine pericardium showed a looser and tinier fiber bundle, a similar free carboxyl concentration, a lower resistance to enzyme degradation, a significantly lower calcification, bearing capacity and damage after being crimped, a better hydrodynamic and adaption with lower cardiac output and deformation of implantation position. Meanwhile the dehydration process of pericardium almost had preserved all the biochemical advantages of two materials. CONCLUSION In this study, porcine and bovine pericardium showed some significant differences in biochemical, mechanical properties and hydrodynamics. According to the results, it was presumed that the thinner porcine pericardium might be more suitable for THV of right heart system. Meanwhile, more attention should be taken for the calcification of THV made by the bovine pericardium.
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Affiliation(s)
- Chang Jin
- Research Center for Biomedical Engineering, Medical Innovation & Research Division, Chinese PLA General Hospital, Beijing, China.,Key Laboratory of Biomedical Engineering and Translational Medicine, Ministry of Industry and Information Technology, Chinese PLA General Hospital, Beijing, China
| | - Li Zhao
- Research Center for Biomedical Engineering, Medical Innovation & Research Division, Chinese PLA General Hospital, Beijing, China.,Key Laboratory of Biomedical Engineering and Translational Medicine, Ministry of Industry and Information Technology, Chinese PLA General Hospital, Beijing, China
| | - Zebin Wu
- Beijing Advanced Innovation Centre for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.,Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beihang University, Beijing, China
| | - Bin Li
- Research Center for Biomedical Engineering, Medical Innovation & Research Division, Chinese PLA General Hospital, Beijing, China.,Key Laboratory of Biomedical Engineering and Translational Medicine, Ministry of Industry and Information Technology, Chinese PLA General Hospital, Beijing, China
| | - Ronghui Liu
- Research Center for Biomedical Engineering, Medical Innovation & Research Division, Chinese PLA General Hospital, Beijing, China.,Key Laboratory of Biomedical Engineering and Translational Medicine, Ministry of Industry and Information Technology, Chinese PLA General Hospital, Beijing, China
| | - Hongping He
- Research Center for Biomedical Engineering, Medical Innovation & Research Division, Chinese PLA General Hospital, Beijing, China.,Key Laboratory of Biomedical Engineering and Translational Medicine, Ministry of Industry and Information Technology, Chinese PLA General Hospital, Beijing, China
| | - Lizhen Wang
- Beijing Advanced Innovation Centre for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.,Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beihang University, Beijing, China
| | - Weidong Wang
- Research Center for Biomedical Engineering, Medical Innovation & Research Division, Chinese PLA General Hospital, Beijing, China.,Key Laboratory of Biomedical Engineering and Translational Medicine, Ministry of Industry and Information Technology, Chinese PLA General Hospital, Beijing, China
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3
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Packy A, D'Souza GA, Farahmand M, Herbertson L, Scully CG. Simulating Radial Pressure Waveforms with a Mock Circulatory Flow Loop to Characterize Hemodynamic Monitoring Systems. Cardiovasc Eng Technol 2021; 13:279-290. [PMID: 34472042 DOI: 10.1007/s13239-021-00575-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 08/15/2021] [Indexed: 11/30/2022]
Abstract
PURPOSE Mock circulatory loops (MCLs) can reproducibly generate physiologically relevant pressures and flows for cardiovascular device testing. These systems have been extensively used to characterize the performance of therapeutic cardiac devices, but historically MCLs have had limited use for assessing patient monitoring systems. Here, we adapted an MCL to include peripheral components and evaluated its utility for qualitative and quantitative benchtop testing of hemodynamic monitoring devices. METHODS An MCL was designed to simulate three physiological hemodynamic states: normovolemia, cardiogenic shock, and hyperdynamic circulation. The system was assessed for stability in pressure and flow values over time, repeatability, waveform morphology, and systemic-peripheral pressure relationships. RESULTS For each condition, cardiac output was controlled to the nearest 0.2 L/min, and flow rate and mean arterial pressure remained stable and repeatable over a 60-s period (n = 5, standard deviation of ± 0.1 L/min and ± 0.84 mmHg, respectively). Transfer function analyses showed that the systemic-peripheral relationships could be adequately manipulated. The results from this MCL were comparable to those from other published MCLs and computational simulations. However, resolving current limitations of the system would further improve its utility. Three pulse contour analysis algorithms were applied to the pressure and flow data from the MCL to demonstrate the potential role of MCLs in characterizing hemodynamic monitoring systems. CONCLUSION Overall, the development of robust analysis methods in conjunction with modified MCLs can expand device testing applications to hemodynamic monitoring systems. Properly validated MCLs can create a stable and reproducible environment for testing patient monitoring systems over their entire operating ranges prior to clinical use.
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Affiliation(s)
- Anna Packy
- Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, MD, USA
- University of Maryland, College Park, MD, USA
| | - Gavin A D'Souza
- Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Masoud Farahmand
- Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Luke Herbertson
- Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Christopher G Scully
- Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Bldg. 62 Rm 1129, 10903 New Hampshire Ave., Silver Spring, MD, 20993, USA.
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4
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Sritharan D, Fathi P, Weaver JD, Retta SM, Wu C, Duraiswamy N. Impact of Clinically Relevant Elliptical Deformations on the Damage Patterns of Sagging and Stretched Leaflets in a Bioprosthetic Heart Valve. Cardiovasc Eng Technol 2018; 9:351-364. [PMID: 29948838 PMCID: PMC10451785 DOI: 10.1007/s13239-018-0366-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 05/21/2018] [Indexed: 01/31/2023]
Abstract
After implantation of a transcatheter bioprosthetic heart valve its original circular circumference may become distorted, which can lead to changes in leaflet coaptation and leaflets that are stretched or sagging. This may lead to early structural deterioration of the valve as seen in some explanted transcatheter heart valves. Our in vitro study evaluates the effect of leaflet deformations seen in elliptical configurations on the damage patterns of the leaflets, with circular valve deformation as the control. Bovine pericardial tissue heart valves were subjected to accelerated wear testing under both circular (N = 2) and elliptical (N = 4) configurations. The elliptical configurations were created by placing the valve inside custom-made elliptical holders, which caused the leaflets to sag or stretch. The hydrodynamic performance of the valves was monitored and high resolution images were acquired to evaluate leaflet damage patterns over time. In the elliptically deformed valves, sagging leaflets experienced more damage from wear compared to stretched leaflets; the undistorted leaflets of the circular valves experienced the least leaflet damage. Free-edge thinning and tearing were the primary modes of damage in the sagging leaflets. Belly region thinning was seen in the undistorted and stretched leaflets. Leaflet and fabric tears at the commissures were seen in all valve configurations. Free-edge tearing and commissure tears were the leading cause of valve hydrodynamic incompetence. Our study shows that mechanical wear affects heart valve pericardial leaflets differently based on whether they are undistorted, stretched, or sagging in a valve configuration. Sagging leaflets are more likely to be subjected to free-edge tear than stretched or undistorted leaflets. Reducing leaflet stress at the free edge of non-circular valve configurations should be an important factor to consider in the design and/or deployment of transcatheter bioprosthetic heart valves to improve their long-term performance.
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Affiliation(s)
- Deepa Sritharan
- Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, WO62, #2206, Silver Spring, MD, 20993, USA
| | - Parinaz Fathi
- Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, WO62, #2206, Silver Spring, MD, 20993, USA
| | - Jason D Weaver
- Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, WO62, #2206, Silver Spring, MD, 20993, USA
| | - Stephen M Retta
- Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, WO62, #2206, Silver Spring, MD, 20993, USA
| | - Changfu Wu
- Division of Cardiovascular Devices (DCD), Office of Device Evaluation (ODE), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, Silver Spring, MD, 20993, USA
| | - Nandini Duraiswamy
- Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, WO62, #2206, Silver Spring, MD, 20993, USA.
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5
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Sirois E, Mao W, Li K, Calderan J, Sun W. Simulated Transcatheter Aortic Valve Flow: Implications of Elliptical Deployment and Under-Expansion at the Aortic Annulus. Artif Organs 2018; 42:E141-E152. [PMID: 29608034 DOI: 10.1111/aor.13107] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 11/06/2017] [Accepted: 12/12/2017] [Indexed: 11/30/2022]
Abstract
Clinical use of transcatheter aortic valves (TAVs) has been associated with abnormal deployment, including oval deployment and under-expansion when placed into calcified aortic annuli. In this study, we performed an integrated computational and experimental investigation to quantify the impact of abnormal deployment at the aortic annulus on TAV hemodynamics. A size 23 mm generic TAV computational model, developed and published previously, was subjected to elliptical deployment at the annulus with eccentricity levels up to 0.68 and to under-expansion of the TAV at the annulus by up to 25%. The hemodynamic performance was quantified for each TAV deployment configuration. TAV opening geometries were fabricated using stereolithography and then subjected to steady forward flow testing in accordance with ISO-5840. Centerline pressure profiles were compared to validate the computational model. Our findings show that slight ellipticity of the TAV may not lead to degeneration of hydrodynamic performance. However, under large ellipticity, increases in transvalvular pressure gradients were observed. Under-expanded deployment has a much greater negative effect on the TAV hemodynamics compared with elliptical deployment. The maximum turbulent viscous shear stress (TVSS) values were found to be significantly larger in under-expanded TAVs. Although the maximum value of TVSS was not large enough to cause hemolysis in all cases, it may cause platelets activation, especially for under-expanded deployments.
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Affiliation(s)
- Eric Sirois
- Tissue Mechanics Laboratory, Biomedical Engineering Department and Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA
| | - Wenbin Mao
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Kewei Li
- Tissue Mechanics Laboratory, Biomedical Engineering Department and Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA
| | - Joseph Calderan
- Tissue Mechanics Laboratory, Biomedical Engineering Department and Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA
| | - Wei Sun
- Tissue Mechanics Laboratory, Biomedical Engineering Department and Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA.,The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
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6
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Feng W, Yang X, Liu Y, Fan Y. An In Vitro Feasibility Study of the Influence of Configurations and Leaflet Thickness on the Hydrodynamics of Deformed Transcatheter Aortic Valve. Artif Organs 2017; 41:735-743. [PMID: 28233370 DOI: 10.1111/aor.12833] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/08/2016] [Accepted: 07/19/2016] [Indexed: 12/19/2022]
Abstract
Clinically, the percutaneous transcatheter aortic valve (TAV) has been reported to be deformed in a noncircular configuration after its implant. The deformation is universal and various, and it leads to serious leakage and durability problems. Even in the same deformation, the leaflets made in different tissue thicknesses may cause different hydrodynamic performances. Simulating the left heart cardiac conditions by a pulse duplicator system, the present study investigated the effects of the aortic annulus deformation and the leaflet tissue thickness on the hydrodynamics of the TAV. Three 22 mm self-expanding TAV samples were fabricated with three different leaflet thicknesses (0.25, 0.4, 0.55 mm). Every sample was successively deformed to be elliptical, triangular, and undersized circular shapes. The hydrodynamics of the TAV were assessed through a quasi-physiological artery pulsatile flow duplicator system. The transvalvular pressure difference, effective orifice area, and regurgitation flow were determined. High-speed video recordings were taken to investigate the leaflet kinematics. The results showed that the triangular deformation produced the poorest valve function while the elliptical deformation led to the slightest difference from the nominal. With increasing leaflet thickness, the effect of configuration deformation on the regurgitation increased. The thinner leaflets were better than the thicker ones in adapting to the deformation but had a higher risk of deterioration.
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Affiliation(s)
- Wentao Feng
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, International Research Center for Implantable and Interventional Medical Devices, Beihang University.,Beijing Key Laboratory for Optimal Design and Evaluation Technology of Implantable & Interventional Medical Devices, Beijing, 100191, China
| | - Xianda Yang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, International Research Center for Implantable and Interventional Medical Devices, Beihang University.,Beijing Key Laboratory for Optimal Design and Evaluation Technology of Implantable & Interventional Medical Devices, Beijing, 100191, China
| | - Yang Liu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, International Research Center for Implantable and Interventional Medical Devices, Beihang University.,Beijing Key Laboratory for Optimal Design and Evaluation Technology of Implantable & Interventional Medical Devices, Beijing, 100191, China
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, International Research Center for Implantable and Interventional Medical Devices, Beihang University.,Beijing Key Laboratory for Optimal Design and Evaluation Technology of Implantable & Interventional Medical Devices, Beijing, 100191, China.,National Research Center for Rehabilitation Technical Aids, Beijing, China
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7
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Dasi LP, Hatoum H, Kheradvar A, Zareian R, Alavi SH, Sun W, Martin C, Pham T, Wang Q, Midha PA, Raghav V, Yoganathan AP. On the Mechanics of Transcatheter Aortic Valve Replacement. Ann Biomed Eng 2017; 45:310-331. [PMID: 27873034 PMCID: PMC5300937 DOI: 10.1007/s10439-016-1759-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 11/03/2016] [Indexed: 01/22/2023]
Abstract
Transcatheter aortic valves (TAVs) represent the latest advances in prosthetic heart valve technology. TAVs are truly transformational as they bring the benefit of heart valve replacement to patients that would otherwise not be operated on. Nevertheless, like any new device technology, the high expectations are dampened with growing concerns arising from frequent complications that develop in patients, indicating that the technology is far from being mature. Some of the most common complications that plague current TAV devices include malpositioning, crimp-induced leaflet damage, paravalvular leak, thrombosis, conduction abnormalities and prosthesis-patient mismatch. In this article, we provide an in-depth review of the current state-of-the-art pertaining the mechanics of TAVs while highlighting various studies guiding clinicians, regulatory agencies, and next-generation device designers.
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Affiliation(s)
- Lakshmi P Dasi
- Department of Biomedical Engineering, Dorothy Davis Heart and Lung Research Institute, The Ohio State University, 473 W 12th Avenue, Columbus, OH, 43210, USA.
| | - Hoda Hatoum
- Department of Biomedical Engineering, Dorothy Davis Heart and Lung Research Institute, The Ohio State University, 473 W 12th Avenue, Columbus, OH, 43210, USA
| | - Arash Kheradvar
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA
| | - Ramin Zareian
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA
| | - S Hamed Alavi
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA
| | - Wei Sun
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Caitlin Martin
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Thuy Pham
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Qian Wang
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Prem A Midha
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Vrishank Raghav
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Ajit P Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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8
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Gunning PS, Saikrishnan N, Yoganathan AP, McNamara LM. Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement. J R Soc Interface 2016; 12:20150737. [PMID: 26674192 DOI: 10.1098/rsif.2015.0737] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Transcatheter aortic valve replacements (TAVRs) are a percutaneous alternative to surgical aortic valve replacements and are used to treat patients with aortic valve stenosis. This minimally invasive procedure relies on expansion of the TAVR stent to radially displace calcified aortic valve leaflets against the aortic root wall. However, these calcium deposits can impede the expansion of the device causing distortion of the valve stent and pericardial tissue leaflets. The objective of this study was to elucidate the impact of eccentric TAVR stent distortion on the dynamic deformation of the tissue leaflets of the prosthesis in vitro. Dual-camera stereophotogrammetry was used to measure the regional variation in strain in a leaflet of a TAVR deployed in nominal circular and eccentric (eccentricity index = 28%) orifices, representative of deployed TAVRs in vivo. It was observed that (i) eccentric stent distortion caused incorrect coaptation of the leaflets at peak diastole resulting in a 'peel-back' leaflet geometry that was not present in the circular valve and (ii) adverse bending of the leaflet, arising in the eccentric valve at peak diastole, caused significantly higher commissure strains compared with the circular valve in both normotensive and hypertensive pressure conditions (normotension: eccentric = 13.76 ± 2.04% versus circular = 11.77 ± 1.61%, p = 0.0014, hypertension: eccentric = 15.07 ± 1.13% versus circular = 13.56 ± 0.87%, p = 0.0042). This study reveals that eccentric distortion of a TAVR stent can have a considerable impact on dynamic leaflet deformation, inducing deleterious bending of the leaflet and increasing commissures strains, which might expedite leaflet structural failure compared to leaflets in a circular deployed valve.
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Affiliation(s)
- Paul S Gunning
- Biomechanics Research Centre, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Republic of Ireland
| | - Neelakantan Saikrishnan
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Ajit P Yoganathan
- Cardiovascular Fluid Mechanics Laboratory, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Laoise M McNamara
- Biomechanics Research Centre, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Republic of Ireland
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9
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Yousefi A, Bark DL, Dasi LP. Effect of Arched Leaflets and Stent Profile on the Hemodynamics of Tri-Leaflet Flexible Polymeric Heart Valves. Ann Biomed Eng 2016; 45:464-475. [PMID: 27307007 DOI: 10.1007/s10439-016-1674-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 05/30/2016] [Indexed: 12/31/2022]
Abstract
Polymeric heart valves (PHV) can be engineered to serve as alternatives for existing prosthetic valves due to higher durability and hemodynamics similar to bioprosthetic valves. The purpose of this study is to evaluate the effect of geometry on PHVs coaptation and hemodynamic performance. The two geometric factors considered are stent profile and leaflet arch length, which were varied across six valve configurations. Three models were created with height to diameter ratio of 0.6, 0.7, and 0.88. The other three models were designed by altering arch height to stent diameter ratio, to be 0, 0.081, and 0.116. Particle image velocimetry experiments were conducted on each PHV to characterize velocity, vorticity, turbulent characteristics, effective orifice area, and regurgitant fraction. This study revealed that the presence of arches as well as higher stent profile reduced regurgitant flow down to 5%, while peak systole downstream velocity reduced to 58% and Reynolds Shear Stress values reduced 40%. Further, earlier reattachment of the forward flow jet was observed in PHVs with leaflet arches. These findings indicate that although both geometric factors help diminish the commissural gap during diastole, leaflet arches induce a larger jet opening, yielding to earlier flow reattachment and lower energy dissipation.
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Affiliation(s)
- Atieh Yousefi
- Department of Biomedical Engineering, Dorothy Davis Heart and Lung Research Institute, The Ohio State University, 473 W 12th Avenue, Columbus, OH, 43210, USA
| | - David L Bark
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Lakshmi P Dasi
- Department of Biomedical Engineering, Dorothy Davis Heart and Lung Research Institute, The Ohio State University, 473 W 12th Avenue, Columbus, OH, 43210, USA.
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10
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Effect of oversizing and elliptical shape of aortic annulus on transcatheter valve hemodynamics: An in vitro study. Int J Cardiol 2016; 208:28-35. [DOI: 10.1016/j.ijcard.2016.01.048] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 12/23/2015] [Accepted: 01/01/2016] [Indexed: 11/17/2022]
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11
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Impact of different aortic valve calcification patterns on the outcome of transcatheter aortic valve implantation: A finite element study. J Biomech 2016; 49:2520-30. [PMID: 27059259 PMCID: PMC5038160 DOI: 10.1016/j.jbiomech.2016.03.036] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 03/19/2016] [Indexed: 11/01/2022]
Abstract
Transcatheter aortic valve implantation (TAVI) can treat symptomatic patients with calcific aortic stenosis. However, the severity and distribution of the calcification of valve leaflets can impair the TAVI efficacy. Here we tackle this issue from a biomechanical standpoint, by finite element simulation of a widely adopted balloon-expandable TAVI in three models representing the aortic root with different scenarios of calcific aortic stenosis. We developed a modeling approach realistically accounting for aortic root pressurization and complex anatomy, detailed calcification patterns, and for the actual stent deployment through balloon-expansion. Numerical results highlighted the dependency on the specific calcification pattern of the "dog-boning" of the stent. Also, local stent distortions were associated with leaflet calcifications, and led to localized gaps between the TAVI stent and the aortic tissues, with potential implications in terms of paravalvular leakage. High stresses were found on calcium deposits, which may be a risk factor for stroke; their magnitude and the extent of the affected regions substantially increased for the case of an "arc-shaped" calcification, running from commissure to commissure. Moreover, high stresses due to the interaction between the aortic wall and the leaflet calcifications were computed in the annular region, suggesting an increased risk for annular damage. Our analyses suggest a relation between the alteration of the stresses in the native anatomical components and prosthetic implant with the presence and distribution of relevant calcifications. This alteration is dependent on the patient-specific features of the calcific aortic stenosis and may be a relevant indicator of suboptimal TAVI results.
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Duraiswamy N, Weaver JD, Ekrami Y, Retta SM, Wu C. A Parametric Computational Study of the Impact of Non-circular Configurations on Bioprosthetic Heart Valve Leaflet Deformations and Stresses: Possible Implications for Transcatheter Heart Valves. Cardiovasc Eng Technol 2016; 7:126-38. [PMID: 26864541 PMCID: PMC10406463 DOI: 10.1007/s13239-016-0259-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 02/02/2016] [Indexed: 11/26/2022]
Abstract
Although generally manufactured as circular devices with symmetric leaflets, transcatheter heart valves can become non-circular post-implantation, the impact of which on the long-term durability of the device is unclear. We investigated the effects of five non-circular (EllipMajor, EllipMinor, D-Shape, TriVertex, TriSides) annular configurations on valve leaflet stresses and valve leaflet deformations through finite element analysis. The highest in-plane principal stresses and strains were observed under an elliptical configuration with an aspect ratio of 1.25 where one of the commissures was on the minor axis of the ellipse. In this elliptical configuration (EllipMinor), the maximum principal stress increased 218% and the maximum principal strain increased 80% as compared with those in the circular configuration, and occurred along the free edge of the leaflet whose commissures were not on the minor axis (i.e., the "stretched" leaflet). The D-Shape configuration was similar to this elliptical configuration, with the degree to which the leaflets were stretched or sagging being less than the EllipMinor configuration. The TriVertex and TriSides configurations had similar leaflet deformation patterns in all three leaflets and similar to the Circular configuration. In the D-Shape, TriVertex, and TriSides configurations, the maximum principal stress was located near the commissures similar to the Circular configuration. In the EllipMinor and EllipMajor configurations, the maximum principal stress occurred near the center of the free edge of the "stretched" leaflets. These results further affirm recommendations by the International Standards Organization (ISO) that pre-clinical testing should consider non-circular configurations for transcatheter valve durability testing.
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Affiliation(s)
- Nandini Duraiswamy
- Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA.
| | - Jason D Weaver
- Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA
| | - Yasamin Ekrami
- Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA
| | - Stephen M Retta
- Office of Science and Engineering Laboratories (OSEL)/Division of Applied Mechanics (DAM), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA
| | - Changfu Wu
- Office of Device Evaluation (ODE)/Division of Cardiovascular Devices (DCD), Center for Devices and Radiological Health (CDRH), U.S. Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA
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Gunning PS, Saikrishnan N, McNamara LM, Yoganathan AP. An in vitro evaluation of the impact of eccentric deployment on transcatheter aortic valve hemodynamics. Ann Biomed Eng 2014; 42:1195-206. [PMID: 24719050 DOI: 10.1007/s10439-014-1008-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 03/31/2014] [Indexed: 10/25/2022]
Abstract
Patients with aortic stenosis present with calcium deposits on the native aortic valve, which can result in non-concentric expansion of Transcatheter Aortic Valve Replacement (TAVR) stents. The objective of this study is to evaluate whether eccentric deployment of TAVRs lead to turbulent blood flow and blood cell damage. Particle Image Velocimetry was used to quantitatively characterize fluid velocity fields, shear stress and turbulent kinetic energy downstream of TAVRs deployed in circular and eccentric orifices representative of deployed TAVRs in vivo. Effective orifice area (EOA) and mean transvalvular pressure gradient (TVG) values did not differ substantially in circular and eccentric deployed valves, with only a minor decrease in EOA observed in the eccentric valve (2.0 cm(2) for circular, 1.9 cm(2) for eccentric). Eccentric deployed TAVR lead to asymmetric systolic jet formation, with increased shear stresses (circular = 97 N/m(2) vs. eccentric = 119 N/m(2)) and regions of turbulence intensity (circular = 180 N/m(2) vs. eccentric = 230 N/m(2)) downstream that was not present in the circular deployed TAVR. The results of this study indicate that eccentric deployment of TAVRs can lead to altered flow characteristics and may potentially increase the hemolytic potential of the valve, which were not captured through hemodynamic evaluation alone.
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Affiliation(s)
- Paul S Gunning
- Biomechanics Research Centre, Department of Biomedical Engineering, National University of Ireland Galway, Galway, Ireland
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Binder RK, Webb JG, Toggweiler S, Freeman M, Barbanti M, Willson AB, Alhassan D, Hague CJ, Wood DA, Leipsic J. Impact of post-implant SAPIEN XT geometry and position on conduction disturbances, hemodynamic performance, and paravalvular regurgitation. JACC Cardiovasc Interv 2014; 6:462-8. [PMID: 23702010 DOI: 10.1016/j.jcin.2012.12.128] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 11/30/2012] [Accepted: 12/21/2012] [Indexed: 01/29/2023]
Abstract
OBJECTIVES This report sought to study the impact of the balloon-expandable SAPIEN XT (Edwards Lifesciences, Irvine, California) transcatheter heart valve (THV) stent frame geometry and position on outcomes of transcatheter aortic valve replacement (TAVR). BACKGROUND Post-implant THV geometry and position might impact atrioventricular conduction, hemodynamic performance, and annular sealing. METHODS Eighty-nine consecutive patients who underwent TAVR with a Sapien XT THV had pre- and post-implant multidetector computed tomography, transthoracic echocardiography, and electrocardiograms performed to assess THV stent geometry, atrioventricular conduction, and hemodynamic performance. RESULTS The THV Circularity (THV eccentricity <10% [eccentricity = minimum stent diameter/maximum stent diameter]) and under-expansion (THV area/nominal THV area <90%) were present in 97.8% (2 of 89) and 0%, respectively. Low THV implantation was associated with new left bundle branch block and complete heart block (3.4 ± 2.0 mm vs. 5.5 ± 2.9 mm, p = 0.01) and with the need for permanent pacemaker implantation (3.5 ± 2.0 mm vs. 7.1 ± 2.5 mm, p = 0.001). In contrast, labeled THV size and THV area oversizing was not associated with atrioventricular conduction disturbances. The relation between inflow stent frame area and annular area was related to paravalvular regurgitation (p = 0.025). Labeled prosthesis size but not prosthesis expansion or eccentricity was related to valve gradient (p = 0.005) and effective orifice area (p < 0.001). CONCLUSIONS Low implantation depth of balloon-expandable THVs is associated with clinically significant new conduction disturbances and permanent pacemaker implantation. Importantly, annular area oversizing was not associated with these complications.
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Affiliation(s)
- Ronald K Binder
- St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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Transcatheter aortic valve replacement with a new self-expanding transcatheter heart valve and motorized delivery system. JACC Cardiovasc Interv 2013; 6:301-7. [PMID: 23517843 DOI: 10.1016/j.jcin.2013.01.129] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 01/04/2013] [Accepted: 01/15/2013] [Indexed: 12/21/2022]
Abstract
OBJECTIVES The aim of this study was to demonstrate feasibility and short- and midterm clinical outcomes with a new self-expanding transcatheter heart valve and motorized delivery system. BACKGROUND Refining transcatheter aortic valve replacement with newly designed bioprostheses and delivery systems is anticipated to facilitate the procedure, reduce the risk of complications, improve outcomes, and widen applicability. METHODS The CENTERA valve (Edwards Lifesciences, Irvine, California) was implanted in 15 patients with symptomatic severe aortic stenosis via femoral or axillary arterial percutaneous access. Patients underwent transesophageal echocardiography during and transthoracic echocardiography and multidetector computed tomography before and after valve implantation. Clinical and echocardiographic follow-up was obtained at 30 days and for the initial 10 patients after 1 year. RESULTS All 15 device implants were successful. Aortic valve area increased from 0.7 ± 0.1 cm(2) to 1.6 ± 0.4 cm(2) post-procedure (p < 0.01) and 1.8 ± 0.3 cm(2) at 1 year. Mean transaortic gradient decreased from 36.3 ± 14.2 mm Hg to 10.6 ± 5.4 mm Hg post-procedure (p < 0.001) and 10.8 ± 4.1 mm Hg at 1 year. Paravalvular aortic regurgitation at 30-day follow-up was none/trivial in 3 (23%), mild in 9 (69%), and moderate in 1 (8%) patient. Four patients (27%) received a new permanent pacemaker. Survival was 87% at 30 days and 80% at 1 year. All surviving patients were in New York Heart Association functional class I (25%) or II (75%) at 1 year. CONCLUSIONS Transcatheter aortic valve replacement with the CENTERA transcatheter heart valve and motorized delivery system is feasible and can lead to good short- and midterm clinical and hemodynamic outcomes.
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Tseng EE, Wisneski A, Azadani AN, Ge L. Engineering perspective on transcatheter aortic valve implantation. Interv Cardiol 2013. [DOI: 10.2217/ica.12.73] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Abstract
In this Editor's Review, articles published in 2011 are organized by category and briefly summarized. As the official journal of The International Federation for Artificial Organs, The International Faculty for Artificial Organs, and the International Society for Rotary Blood Pumps, Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level."Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ replacement, recovery, and regeneration from all over the world. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers, the quality expected from such a journal would not be possible. We also express our special thanks to our Publisher, Wiley-Blackwell, for their expert attention and support in the production and marketing of Artificial Organs. In this Editor's Review, that historically has been widely well-received by our readership, we aim to provide a brief reflection of the currently available worldwide knowledge that is intended to advance and better human life while providing insight for continued application of technologies and methods of organ replacement, recovery, and regeneration. We look forward to recording further advances in the coming years.
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Affiliation(s)
- Paul S Malchesky
- Artificial Organs Editorial Office, 10 West Erie Street, Painesville, OH 44077, USA.
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