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In Vitro 2D PIV Measurements and Related Aperture Areas of Tricuspid Bioprosthetic Mitral Valves at the beginning of Diastole. Int J Artif Organs 2016; 39:253-7. [DOI: 10.5301/ijao.5000494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2016] [Indexed: 11/20/2022]
Abstract
Purpose Besides ventricular parameters, the design and angular orientation of a prosthetic heart valve induce a specific flow field. The aim of this study was to know the inflow characteristics of a left ventricular model (LVM), investigating the behavior of tricuspid bioprosthetic mitral valves in terms of velocity profiles and related valve aperture areas at the beginning of diastole, under different conditions. Methods 3 heart rates (HRs) were established in the LVM and each mitral bioprosthesis (27 and 31 mm diameter) was installed in 2 orientations, rotated by 180°. For each experimental setup, 2-dimensional particle image velocimetry (2D PIV) measurements and simultaneous mitral valve (MV) area detection were obtained from 50 samples. Results The results from the velocity profiles immediately downstream of mitral bioprostheses showed the influence of valve orientation for moderate HRs, although for a similar magnitude of mean velocity vectors. The geometries of MV open areas for each HR were similar regardless of valve orientation, except for the 27-mm valve at 90 beats per minute (bpm), and for the 31-mm valve at 60 bpm. Moreover, for each HR, similar percentages of valve open area were obtained regardless of MV nominal diameters. Conclusions In conclusion, the experimental setup for the 2D PIV measurements synchronized with the MV area detection was a useful tool for knowing the inflow characteristics of the LVM.
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Percutaneous Double Lumen Cannula for Right Ventricle Assist Device System: A Computational Fluid Dynamics Study. Biocybern Biomed Eng 2016; 36:482-490. [PMID: 27570334 DOI: 10.1016/j.bbe.2016.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES Our goal is to develop a double lumen cannula (DLC) for a percutaneous right ventricular assist device (pRVAD) in order to eliminate two open chest surgeries for RVAD installation and removal. The objective of this study was to evaluate the performance, flow pattern, blood hemolysis, and thrombosis potential of the pRVAD DLC. METHODS Computational fluid dynamics (CFD), using the finite volume method, was performed on the pRVAD DLC. For Reynolds numbers <4000, the laminar model was used to describe the blood flow behavior, while shear-stress transport k-ω model was used for Reynolds numbers >4000. Bench testing with a 27 Fr prototype was performed to validate the CFD calculations. RESULTS There was <1.3% difference between the CFD and experimental pressure drop results. The Lagrangian approach revealed a low index of hemolysis (0.012% in drainage lumen and 0.0073% in infusion lumen) at 5 l/min flow rate. Blood stagnancy and recirculation regions were found in the CFD analysis, indicating a potential risk for thrombosis. CONCLUSIONS The pRVAD DLC can handle up to 5 l/min flow with limited potential hemolysis. Further modification of the pRVAD DLC is needed to address blood stagnancy and recirculation.
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103
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Frese L, Sasse T, Sanders B, Baaijens FPT, Beer GM, Hoerstrup SP. Are adipose-derived stem cells cultivated in human platelet lysate suitable for heart valve tissue engineering? J Tissue Eng Regen Med 2016. [DOI: 10.1002/term.2118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Laura Frese
- Swiss Centre for Regenerative Medicine; University Hospital of Zürich; Switzerland
| | - Tom Sasse
- Swiss Centre for Regenerative Medicine; University Hospital of Zürich; Switzerland
| | - Bart Sanders
- Department of Biomedical Engineering; Eindhoven University of Technology; The Netherlands
| | - Frank P. T. Baaijens
- Department of Biomedical Engineering; Eindhoven University of Technology; The Netherlands
| | - Gertrude M. Beer
- Clinic for Plastic, Aesthetic and Reconstructive Surgery; Zurich Switzerland
| | - Simon P. Hoerstrup
- Swiss Centre for Regenerative Medicine; University Hospital of Zürich; Switzerland
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104
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Bark DL, Yousefi A, Forleo M, Vaesken A, Heim F, Dasi LP. Reynolds shear stress for textile prosthetic heart valves in relation to fabric design. J Mech Behav Biomed Mater 2016; 60:280-287. [PMID: 26919564 DOI: 10.1016/j.jmbbm.2016.01.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 01/18/2016] [Indexed: 10/22/2022]
Abstract
The most widely implanted prosthetic heart valves are either mechanical or bioprosthetic. While the former suffers from thrombotic risks, the latter suffers from a lack of durability. Textile valves, alternatively, can be designed with durability and to exhibit hemodynamics similar to the native valve, lowering the risk for thrombosis. Deviations from native valve hemodynamics can result in an increased Reynolds Shear Stress (RSS), which has the potential to instigate hemolysis or shear-induced thrombosis. This study is aimed at characterizing flow in multiple textile valve designs with an aim of developing a low profile valve. Valves were created using a shaping process based on heating a textile membrane and placed within a left heart simulator. Turbulence and bulk hemodynamics were assessed through particle imaging velocimetry, along with flow and pressure measurements. Overall, RSS was reduced for low profile valves relative to high profile valves, but was otherwise similar among low profile valves involving different fabric designs. However, leakage was found in 3 of the 4 low profile valve designs driving the fabric design for low profile valves. Through textile design, low profile valves can be created with favorable hemodynamics.
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Affiliation(s)
- David L Bark
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States; School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | - Atieh Yousefi
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States; Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Marcio Forleo
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States
| | | | - Frederic Heim
- Université de Haute Alsace/ENSISA-LPMT, Mulhouse, France
| | - Lakshmi P Dasi
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, United States; School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States; Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States.
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105
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Kasahara H, Inoue Y, Suzuki S. Recurrent infarctions due to a dome-shaped pannus above the mitral valve prosthesis. J Thorac Dis 2016; 8:E130-2. [PMID: 26904241 DOI: 10.3978/j.issn.2072-1439.2016.01.29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
This report describes a unique case of a 56-year-old female who suffered from recurrent stroke after double mechanical valve replacement. During the four years after the surgery, she remained in normal sinus rhythm, received adequate anticoagulation therapy, and no apparent left atrial thrombus was detected. She underwent redo surgery to prevent further stroke after fourth instance of cerebral infarction. Intraoperative findings revealed a 'dome-shaped' pannus formation covering the sewing ring of the mitral prosthesis circumferentially, probably leading to clot formation and repeated infarctions. She has been stroke free for three years after pannus resection.
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Affiliation(s)
- Hirofumi Kasahara
- 1 Department of Cardiovascular Surgery, National Hospital Organization Saitama Hospital, Wako, Japan ; 2 Department of Cardiovascular Surgery, Hiratsuka City Hospital, Hiratsuka, Japan
| | - Yoshito Inoue
- 1 Department of Cardiovascular Surgery, National Hospital Organization Saitama Hospital, Wako, Japan ; 2 Department of Cardiovascular Surgery, Hiratsuka City Hospital, Hiratsuka, Japan
| | - Satoru Suzuki
- 1 Department of Cardiovascular Surgery, National Hospital Organization Saitama Hospital, Wako, Japan ; 2 Department of Cardiovascular Surgery, Hiratsuka City Hospital, Hiratsuka, Japan
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106
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Jahandardoost M, Fradet G, Mohammadi H. Effect of heart rate on the hemodynamics of bileaflet mechanical heart valves’ prostheses (St. Jude Medical) in the aortic position and in the opening phase: A computational study. Proc Inst Mech Eng H 2016; 230:175-90. [DOI: 10.1177/0954411915624451] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 11/16/2015] [Indexed: 11/16/2022]
Abstract
To date, to the best of the authors’ knowledge, in almost all of the studies performed around the hemodynamics of bileaflet mechanical heart valves, a heart rate of 70–72 beats/min has been considered. In fact, the heart rate of ~72 beats/min does not represent the entire normal physiological conditions under which the aortic or prosthetic valves function. The heart rates of 120 or 50 beats/min may lead to hemodynamic complications, such as plaque formation and/or thromboembolism in patients. In this study, the hemodynamic performance of the bileaflet mechanical heart valves in a wide range of normal and physiological heart rates, that is, 60–150 beats/min, was studied in the opening phase. The model considered in this study was a St. Jude Medical bileaflet mechanical heart valve with the inner diameter of 27 mm in the aortic position. The hemodynamics of the native valve and the St. Jude Medical valve were studied in a variety of heart rates in the opening phase and the results were carefully compared. The results indicate that peak values of the velocity profile downstream of the valve increase as heart rate increases, as well as the location of the maximum velocity changes with heart rate in the St. Jude Medical valve model. Also, the maximum values of shear stress and wall shear stresses downstream of the valve are proportional to heart rate in both models. Interestingly, the maximum shear stress and wall shear stress values in both models are in the same range when heart rate is <90 beats/min; however, these values significantly increase in the St. Jude Medical valve model when heart rate is >90 beats/min (up to ~40% growth compared to that of the native valve). The findings of this study may be of importance in the hemodynamic performance of bileaflet mechanical heart valves. They may also play an important role in design improvement of conventional prosthetic heart valves and the design of the next generation of prosthetic valves, such as percutaneous valves.
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Affiliation(s)
- Mehdi Jahandardoost
- The Heart Valve Performance Laboratory, School of Engineering, Faculty of Applied Science, University of British Columbia, Kelowna, BC, Canada
| | - Guy Fradet
- The Heart Valve Performance Laboratory, School of Engineering, Faculty of Applied Science, University of British Columbia, Kelowna, BC, Canada
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Hadi Mohammadi
- The Heart Valve Performance Laboratory, School of Engineering, Faculty of Applied Science, University of British Columbia, Kelowna, BC, Canada
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- Biomedical Engineering Graduate Program, Faculty of Applied Science, University of British Columbia, Vancouver, BC, Canada
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107
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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: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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108
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Marei I, Chester A, Carubelli I, Prodromakis T, Trantidou T, Yacoub MH. Assessment of Parylene C Thin Films for Heart Valve Tissue Engineering. Tissue Eng Part A 2015; 21:2504-14. [PMID: 26101808 DOI: 10.1089/ten.tea.2014.0607] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Scaffolds are a key component of tissue-engineered heart valves (TEHVs). Several approaches had been adopted in the design of scaffolds using both natural and synthetic resources. We have investigated the suitability of parylene C (PC), a vapor deposited polymeric material, for the use as a scaffold in TEHV. AIMS To evaluate the adsorption of extracellular matrix components onto plasma-activated PC and study the biocompatibility of PC by measuring cellular adhesion, viability, apoptosis, and phenotypic expression of valve endothelial and interstitial cells. Finally, the mechanical properties of PC were compared with those of native aortic valve cusp tissue. METHODS PC slides were plasma activated and then coated with gelatin, type I collagen, or fibronectin. Porcine pulmonary valve endothelial and interstitial cells were then grown on plasma oxidized PC with different types of coatings and their adhesion was observed after 20 h of incubation. Cell viability was tested using the MTS assay, and apoptosis was estimated using TUNEL staining. The mechanical properties of PC and valve tissue were measured using a Bose Mechanical Tester. Finally, cell-seeded PC films were exposed to pulsatile pressure and aortic shear stress, respectively, to test their durability in a dynamic environment. RESULTS Our findings show that collagen and fibronectin could bind to plasma oxidized PC. Both valve endothelial and interstitial cells adhered to protein-coated ECM. PC had a profile of mechanical stiffness and ultimate tensile strength that were comparable with or in excess of those seen in porcine aortic valve cusps. Cells were still attached to PC films after 3 days of exposure to up to 50 mmHg pulsatile pressure or aortic levels of shear stress. CONCLUSION PC is a promising candidate for use as a scaffold in tissue engineering heart valves. Additional studies are required to determine both the durability and long-term performance of cell-seeded PC when in a similar hemodynamic environment to that of the aortic valve.
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Affiliation(s)
- Isra Marei
- 1 Heart Science Centre, National Heart and Lung Institute , United Kingdom .,2 Imperial College, London, United Kingdom .,3 Qatar Cardiovascular Research Center , Doha, Qatar
| | - Adrian Chester
- 1 Heart Science Centre, National Heart and Lung Institute , United Kingdom .,2 Imperial College, London, United Kingdom
| | - Ivan Carubelli
- 1 Heart Science Centre, National Heart and Lung Institute , United Kingdom
| | - Themistoklis Prodromakis
- 4 Centre for Bio-Inspired Technology, Institute of Biomedical Engineering , Imperial College London, London, United Kingdom .,5 Nano Group, ECS, University of Southampton , Southampton, United Kingdom
| | - Tatiana Trantidou
- 4 Centre for Bio-Inspired Technology, Institute of Biomedical Engineering , Imperial College London, London, United Kingdom .,5 Nano Group, ECS, University of Southampton , Southampton, United Kingdom
| | - Magdi H Yacoub
- 1 Heart Science Centre, National Heart and Lung Institute , United Kingdom .,2 Imperial College, London, United Kingdom
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109
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Lawley CM, Lain SJ, Algert CS, Ford JB, Figtree GA, Roberts CL. Prosthetic heart valves in pregnancy, outcomes for women and their babies: a systematic review and meta-analysis. BJOG 2015; 122:1446-55. [PMID: 26119028 DOI: 10.1111/1471-0528.13491] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2015] [Indexed: 11/27/2022]
Abstract
BACKGROUND Historically, pregnancies among women with prosthetic heart valves have been associated with an increased incidence of adverse outcomes. OBJECTIVES Systematic review to assess risk of adverse pregnancy outcomes among women with a prosthetic heart valve(s) over the last 20 years. SEARCH STRATEGY Electronic literature search of Medline, The Cochrane Library, Cumulative Index to Nursing and Allied Health Literature and Embase to find recent studies. SELECTION CRITERIA Studies of pregnant women with heart valve prostheses including trials, cohort studies and unselected case series. DATA COLLECTION AND ANALYSIS Primary analysis calculated absolute risks and 95% confidence intervals (CI) for pregnancy outcomes using a random effects model. The Freeman-Tukey transformation was utilised in secondary analysis due to the large number of individual study outcomes with zero events. MAIN RESULTS Eleven studies capturing 499 pregnancies among women with heart valve prostheses, including 256 mechanical and 59 bioprosthetic, were eligible for inclusion. Pooled estimate of maternal mortality was 1.2/100 pregnancies (95% CI 0.5-2.2), for mechanical valves subgroup 1.8/100 (95% CI 0.5-3.7) and bioprosthetic subgroup 0.7/100 (95% CI 0.1-4.5), overall pregnancy loss 20.8/100 pregnancies (95% CI 9.5-35.1), perinatal mortality 5.0/100 births (95%CI 1.8-9.8) and thromboembolism 9.3/100 pregnancies (95% CI 4.0-16.5). CONCLUSIONS Women with heart valve prostheses experienced higher rates of adverse outcomes than expected in a general obstetric population; however, lower than previously reported. Women with bioprostheses had significantly fewer thromboembolic events compared to women with mechanical valves. Women should be counselled pre-pregnancy about risk of maternal death and pregnancy loss. Vigilant surveillance by a multidisciplinary team throughout the perinatal period remains warranted for these women and their infants. TWEETABLE ABSTRACT Metaanalysis suggests improvement in #pregnancy outcomes among women with #heartvalveprostheses.
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Affiliation(s)
- C M Lawley
- Clinical Population Perinatal Health Research, Kolling Institute, University of Sydney, Sydney, NSW, Australia.,Department of Cardiology, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - S J Lain
- Clinical Population Perinatal Health Research, Kolling Institute, University of Sydney, Sydney, NSW, Australia
| | - C S Algert
- Clinical Population Perinatal Health Research, Kolling Institute, University of Sydney, Sydney, NSW, Australia
| | - J B Ford
- Clinical Population Perinatal Health Research, Kolling Institute, University of Sydney, Sydney, NSW, Australia
| | - G A Figtree
- Department of Cardiology, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - C L Roberts
- Clinical Population Perinatal Health Research, Kolling Institute, University of Sydney, Sydney, NSW, Australia
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110
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Coupled Simulation of Heart Valves: Applications to Clinical Practice. Ann Biomed Eng 2015; 43:1626-39. [PMID: 26101029 DOI: 10.1007/s10439-015-1348-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 05/26/2015] [Indexed: 12/16/2022]
Abstract
The last few decades have seen great advances in the understanding of heart valves, and consequently, in the development of novel treatment modalities and surgical procedures for valves afflicted by disease. This is due in part to the profound advancements in computing technology and noninvasive medical imaging techniques that have made it possible to numerically model the complex heart valve systems characterized by distinct features at different length scales and various interacting processes. In this article, we highlight the importance of explicitly coupling these multiple scales and diverse processes to accurately simulate the true behavior of the heart valves, in health and disease. We examine some of the computational modeling studies that have a direct consequence on clinical practice.
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111
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Ismail M, Kabinejadian F, Nguyen YN, Tay E, Kim S, Leo HL. In Vitro Investigation of the Hemodynamics of Transcatheter Heterotopic Valves Implantation in the Cavo-Atrial Junction. Artif Organs 2015; 39:803-14. [DOI: 10.1111/aor.12457] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Munirah Ismail
- Department of Biomedical Engineering; National University of Singapore; Singapore
| | - Foad Kabinejadian
- Department of Biomedical Engineering; National University of Singapore; Singapore
| | - Yen Ngoc Nguyen
- Department of Biomedical Engineering; National University of Singapore; Singapore
| | - Edgar Tay
- Department of Cardiac, Thoracic, and Vascular Surgery; National University of Singapore; Singapore
| | - Sangho Kim
- Department of Biomedical Engineering; National University of Singapore; Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering; National University of Singapore; Singapore
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112
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Development of self-expanding valved stents with autologous tubular leaflet tissues for transcatheter valve implantation. J Artif Organs 2015; 18:228-35. [DOI: 10.1007/s10047-015-0820-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/03/2015] [Indexed: 10/24/2022]
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113
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Arjunon S, Ardana PH, Saikrishnan N, Madhani S, Foster B, Glezer A, Yoganathan AP. Design of a pulsatile flow facility to evaluate thrombogenic potential of implantable cardiac devices. J Biomech Eng 2015; 137:045001. [PMID: 25587891 DOI: 10.1115/1.4029579] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Indexed: 11/08/2022]
Abstract
Due to expensive nature of clinical trials, implantable cardiac devices should first be extensively characterized in vitro. Prosthetic heart valves (PHVs), an important class of these devices, have been shown to be associated with thromboembolic complications. Although various in vitro systems have been designed to quantify blood-cell damage and platelet activation caused by nonphysiological hemodynamic shear stresses in these PHVs, very few systems attempt to characterize both blood damage and fluid dynamics aspects of PHVs in the same test system. Various numerical modeling methodologies are also evolving to simulate the structural mechanics, fluid mechanics, and blood damage aspects of these devices. This article presents a completely hemocompatible small-volume test-platform that can be used for thrombogenicity studies and experimental fluid mechanics characterization. Using a programmable piston pump to drive freshly drawn human blood inside a cylindrical column, the presented system can simulate various physiological and pathophysiological conditions in testing PHVs. The system includes a modular device-mounting chamber, and in this presented case, a 23 mm St. Jude Medical (SJM) Regents® mechanical heart valve (MHV) in aortic position was used as the test device. The system was validated for its capability to quantify blood damage by measuring blood damage induced by the tester itself (using freshly drawn whole human blood). Blood damage levels were ascertained through clinically relevant assays on human blood while fluid dynamics were characterized using time-resolved particle image velocimetry (PIV) using a blood-mimicking fluid. Blood damage induced by the tester itself, assessed through Thrombin-anti-Thrombin (TAT), Prothrombin factor 1.2 (PF1.2), and hemolysis (Drabkins assay), was within clinically accepted levels. The hydrodynamic performance of the tester showed consistent, repeatable physiological pressure and flow conditions. In addition, the system contains proximity sensors to accurately capture leaflet motion during the entire cardiac cycle. The PIV results showed skewing of the leakage jet, caused by the asymmetric closing of the two leaflets. All these results are critical to characterizing the blood damage and fluid dynamics characteristics of the SJM Regents® MHV, proving the utility of this tester as a precise system for assessing the hemodynamics and thrombogenicity for various PHVs.
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114
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Kheradvar A, Groves EM, Goergen CJ, Alavi SH, Tranquillo R, Simmons CA, Dasi LP, Grande-Allen KJ, Mofrad MRK, Falahatpisheh A, Griffith B, Baaijens F, Little SH, Canic S. Emerging Trends in Heart Valve Engineering: Part II. Novel and Standard Technologies for Aortic Valve Replacement. Ann Biomed Eng 2014; 43:844-57. [DOI: 10.1007/s10439-014-1191-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 11/13/2014] [Indexed: 11/29/2022]
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115
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Kheradvar A, Groves EM, Simmons CA, Griffith B, Alavi SH, Tranquillo R, Dasi LP, Falahatpisheh A, Grande-Allen KJ, Goergen CJ, Mofrad MRK, Baaijens F, Canic S, Little SH. Emerging trends in heart valve engineering: Part III. Novel technologies for mitral valve repair and replacement. Ann Biomed Eng 2014; 43:858-70. [PMID: 25287646 DOI: 10.1007/s10439-014-1129-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/17/2014] [Indexed: 11/29/2022]
Abstract
In this portion of an extensive review of heart valve engineering, we focus on the current and emerging technologies and techniques to repair or replace the mitral valve. We begin with a discussion of the currently available mechanical and bioprosthetic mitral valves followed by the rationale and limitations of current surgical mitral annuloplasty methods; a discussion of the technique of neo-chordae fabrication and implantation; a review the procedures and clinical results for catheter-based mitral leaflet repair; a highlight of the motivation for and limitations of catheter-based annular reduction therapies; and introduce the early generation devices for catheter-based mitral valve replacement.
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Affiliation(s)
- Arash Kheradvar
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA,
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116
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Bioengineering Strategies for Polymeric Scaffold for Tissue Engineering an Aortic Heart Valve: An Update. Int J Artif Organs 2014; 37:651-67. [DOI: 10.5301/ijao.5000339] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2014] [Indexed: 12/17/2022]
Abstract
The occurrence of dysfunctional aortic valves is increasing every year, and current replacement heart valves, although having been shown to be clinically successful, are only short-term solutions and suffer from many agonizing long-term drawbacks. The tissue engineering of heart valves is recognized as one of the most promising answers for aortic valve disease therapy, but overcoming current shortcomings will require multidisciplinary efforts. The use of a polymeric scaffold to guide the growth of the tissue is the most common approach to generate a new tissue for an aortic heart valve. However, optimizing the design of the scaffold, in terms of biocompatibility, surface morphology for cell attachments and the correct rate of degradation is critical in creating a viable tissue-engineered aortic heart valve. This paper highlights the bioengineering strategies that need to be followed to construct a polymeric scaffold of sufficient mechanical integrity, with superior surface morphologies, that is capable of mimicking the valve dynamics in vivo. The current challenges and future directions of research for creating tissue-engineered aortic heart valves are also discussed.
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Herbertson LH, Olia SE, Daly A, Noatch CP, Smith WA, Kameneva MV, Malinauskas RA. Multilaboratory study of flow-induced hemolysis using the FDA benchmark nozzle model. Artif Organs 2014; 39:237-48. [PMID: 25180887 DOI: 10.1111/aor.12368] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Multilaboratory in vitro blood damage testing was performed on a simple nozzle model to determine how different flow parameters and blood properties affect device-induced hemolysis and to generate data for comparison with computational fluid dynamics-based predictions of blood damage as part of an FDA initiative for assessing medical device safety. Three independent laboratories evaluated hemolysis as a function of nozzle entrance geometry, flow rate, and blood properties. Bovine blood anticoagulated with acid citrate dextrose solution (2-80 h post-draw) was recirculated through nozzle-containing and paired nozzle-free control loops for 2 h. Controlled parameters included hematocrit (36 ± 1.5%), temperature (25 °C), blood volume, flow rate, and pressure. Three nozzle test conditions were evaluated (n = 26-36 trials each): (i) sudden contraction at the entrance with a blood flow rate of 5 L/min, (ii) gradual cone at the entrance with a 6-L/min blood flow rate, and (iii) sudden-contraction inlet at 6 L/min. The blood damage caused only by the nozzle model was calculated by subtracting the hemolysis generated by the paired control loop test. Despite high intralaboratory variability, significant differences among the three test conditions were observed, with the sharp nozzle entrance causing the most hemolysis. Modified index of hemolysis (MIHnozzle ) values were 0.292 ± 0.249, 0.021 ± 0.128, and 1.239 ± 0.667 for conditions i-iii, respectively. Porcine blood generated hemolysis results similar to those obtained with bovine blood. Although the interlaboratory hemolysis results are only applicable for the specific blood parameters and nozzle model used here, these empirical data may help to advance computational fluid dynamics models for predicting blood damage.
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Affiliation(s)
- Luke H Herbertson
- Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD, USA
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118
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Annerel S, Claessens T, Degroote J, Segers P, Vierendeels J. Validation of a numerical FSI simulation of an aortic BMHV by in vitro PIV experiments. Med Eng Phys 2014; 36:1014-23. [PMID: 24924383 DOI: 10.1016/j.medengphy.2014.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 04/01/2014] [Accepted: 05/05/2014] [Indexed: 10/25/2022]
Abstract
In this paper, a validation of a recently developed fluid-structure interaction (FSI) coupling algorithm to simulate numerically the dynamics of an aortic bileaflet mechanical heart valve (BMHV) is performed. This validation is done by comparing the numerical simulation results with in vitro experiments. For the in vitro experiments, the leaflet kinematics and flow fields are obtained via the particle image velocimetry (PIV) technique. Subsequently, the same case is numerically simulated by the coupling algorithm and the resulting leaflet kinematics and flow fields are obtained. Finally, the results are compared, revealing great similarity in leaflet motion and flow fields between the numerical simulation and the experimental test. Therefore, it is concluded that the developed algorithm is able to capture very accurately all the major leaflet kinematics and dynamics and can be used to study and optimize the design of BMHVs.
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Affiliation(s)
- S Annerel
- Ghent University, Department of Flow, Heat and Combustion Mechanics, Sint-Pietersnieuwstraat 41, B-9000 Ghent, Belgium.
| | - T Claessens
- Ghent University, Department of Industrial Technology and Construction, Valentin Vaerwyckweg 1, B-9000 Ghent, Belgium.
| | - J Degroote
- Ghent University, Department of Flow, Heat and Combustion Mechanics, Sint-Pietersnieuwstraat 41, B-9000 Ghent, Belgium.
| | - P Segers
- Ghent University, iMinds Medical IT, IBiTech-bioMMeda, De Pintelaan 185, B-9000 Ghent, Belgium.
| | - J Vierendeels
- Ghent University, Department of Flow, Heat and Combustion Mechanics, Sint-Pietersnieuwstraat 41, B-9000 Ghent, Belgium.
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Guyette JP, Gilpin SE, Charest JM, Tapias LF, Ren X, Ott HC. Perfusion decellularization of whole organs. Nat Protoc 2014; 9:1451-68. [PMID: 24874812 DOI: 10.1038/nprot.2014.097] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The native extracellular matrix (ECM) outlines the architecture of organs and tissues. It provides a unique niche of composition and form, which serves as a foundational scaffold that supports organ-specific cell types and enables normal organ function. Here we describe a standard process for pressure-controlled perfusion decellularization of whole organs for generating acellular 3D scaffolds with preserved ECM protein content, architecture and perfusable vascular conduits. By applying antegrade perfusion of detergents and subsequent washes to arterial vasculature at low physiological pressures, successful decellularization of complex organs (i.e., hearts, lungs and kidneys) can be performed. By using appropriate modifications, pressure-controlled perfusion decellularization can be achieved in small-animal experimental models (rat organs, 4-5 d) and scaled to clinically relevant models (porcine and human organs, 12-14 d). Combining the unique structural and biochemical properties of native acellular scaffolds with subsequent recellularization techniques offers a novel platform for organ engineering and regeneration, for experimentation ex vivo and potential clinical application in vivo.
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Affiliation(s)
- Jacques P Guyette
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Harvard Medical School, Boston, Massachusetts, USA. [3]
| | - Sarah E Gilpin
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Harvard Medical School, Boston, Massachusetts, USA. [3]
| | - Jonathan M Charest
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Luis F Tapias
- 1] Harvard Medical School, Boston, Massachusetts, USA. [2] Department of Surgery, Division of Thoracic Surgery, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Xi Ren
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Harvard Medical School, Boston, Massachusetts, USA
| | - Harald C Ott
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Harvard Medical School, Boston, Massachusetts, USA. [3] Department of Surgery, Division of Thoracic Surgery, Massachusetts General Hospital, Boston, Massachusetts, USA. [4] Harvard Stem Cell Institute, Boston, Massachusetts, USA
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120
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Stewart PS. Biophysics of biofilm infection. Pathog Dis 2014; 70:212-8. [PMID: 24376149 PMCID: PMC3984611 DOI: 10.1111/2049-632x.12118] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 11/25/2013] [Accepted: 12/03/2013] [Indexed: 01/22/2023] Open
Abstract
This article examines a likely basis of the tenacity of biofilm infections that has received relatively little attention: the resistance of biofilms to mechanical clearance. One way that a biofilm infection persists is by withstanding the flow of fluid or other mechanical forces that work to wash or sweep microorganisms out of the body. The fundamental criterion for mechanical persistence is that the biofilm failure strength exceeds the external applied stress. Mechanical failure of the biofilm and release of planktonic microbial cells is also important in vivo because it can result in dissemination of infection. The fundamental criterion for detachment and dissemination is that the applied stress exceeds the biofilm failure strength. The apparent contradiction for a biofilm to both persist and disseminate is resolved by recognizing that biofilm material properties are inherently heterogeneous. There are also mechanical aspects to the ways that infectious biofilms evade leukocyte phagocytosis. The possibility of alternative therapies for treating biofilm infections that work by reducing biofilm cohesion could (1) allow prevailing hydrodynamic shear to remove biofilm, (2) increase the efficacy of designed interventions for removing biofilms, (3) enable phagocytic engulfment of softened biofilm aggregates, and (4) improve phagocyte mobility and access to biofilm.
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Affiliation(s)
- Philip S. Stewart
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717-3980, USA, (406) 994-1960 (phone), (406) 994-6098 (fax)
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121
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Bazan O, Ortiz JP, Vieira Junior FU, Vieira RW, Antunes N, Tabacow FBD, Costa ET, Petrucci Junior O. Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves. Braz J Cardiovasc Surg 2014; 28:462-9. [PMID: 24598950 PMCID: PMC4389440 DOI: 10.5935/1678-9741.20130076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 09/16/2013] [Indexed: 11/21/2022] Open
Abstract
Introduction In vitro hydrodynamic characterization of prosthetic heart valves
provides important information regarding their operation, especially if performed
by noninvasive techniques of anemometry. Once velocity profiles for each valve are
provided, it is possible to compare them in terms of hydrodynamic performance. In
this first experimental study using laser doppler anemometry with mechanical
valves, the simulations were performed at a steady flow workbench. Objective To compare unidimensional velocity profiles at the central plane of two
bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models)
exposed to a steady flow regime, on four distinct sections, three downstream and
one upstream. Methods To provide similar conditions for the flow through each prosthesis by a steady
flow workbench (water, flow rate of 17L/min. ) and, for the same sections and
sweeps, to obtain the velocity profiles of each heart valve by unidimensional
measurements. Results It was found that higher velocities correspond to the prosthesis with smaller
inner diameter and instabilities of flow are larger as the section of interest is
closer to the valve. Regions of recirculation, stagnation of flow, low pressure,
and flow peak velocities were also found. Conclusions Considering the hydrodynamic aspect and for every section measured, it could be
concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21
AJ - 501 model (Master Series). Based on the results, future studies can choose to
focus on specific regions of the these valves.
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Affiliation(s)
- Ovandir Bazan
- University of São Paulo (USP), Polytechnic School, Mechanical
Engineering Department, São Paulo, SP, Brazil
- Correspondence address: Ovandir Bazan, Av. Prof. Mello de Moraes,
2231 - Cidade Universitária Armando de Salles Oliveira - São Paulo, SP, Brazil - Zip
code: 05508-030. E-mail:
| | - Jayme Pinto Ortiz
- University of São Paulo (USP), Polytechnic School, Mechanical
Engineering Department, São Paulo, SP, Brazil
| | - Francisco Ubaldo Vieira Junior
- University of Campinas (UNICAMP), Department of Surgery, Medicine
Center and Experimental Surgery, Campinas, SP, Brazil
- University of Campinas (UNICAMP), Center for Biomedical Engineering,
Campinas, SP, Brazil
| | - Reinaldo Wilson Vieira
- University of Campinas (UNICAMP), Department of Surgery, Medicine
Center and Experimental Surgery, Campinas, SP, Brazil
| | - Nilson Antunes
- University of Campinas (UNICAMP), Department of Surgery, Medicine
Center and Experimental Surgery, Campinas, SP, Brazil
| | | | - Eduardo Tavares Costa
- University of Campinas (UNICAMP), Center for Biomedical Engineering,
Campinas, SP, Brazil
| | - Orlando Petrucci Junior
- University of Campinas (UNICAMP), Department of Surgery, Medicine
Center and Experimental Surgery, Campinas, SP, Brazil
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122
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Prawel DA, Dean H, Forleo M, Lewis N, Gangwish J, Popat KC, DASI LP, James SP. Hemocompatibility and Hemodynamics of Novel Hyaluronan-Polyethylene Materials for Flexible Heart Valve Leaflets. Cardiovasc Eng Technol 2014; 5:70-81. [PMID: 24729797 PMCID: PMC3979580 DOI: 10.1007/s13239-013-0171-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Polymeric heart valves (PHVs) hold the promise to be more durable than bioprosthetic heart valves and less thrombogenic than mechanical heart valves. We introduce a new framework to manufacture hemocompatible polymeric leaflets for HV (PHV) applications using a novel material comprised of interpenetrating networks (IPNs) of hyaluronan (HA) and linear low density polyethylene (LLDPE). We establish and characterize the feasibility of the material as a substitute leaflet material through basic hemodynamic measurements in a trileaflet configuration, in addition to demonstrating superior platelet response and clotting characteristics. Plain LLDPE sheets were swollen in a solution of silylated-HA, the silylated-HA was then crosslinked to itself before it was reverted back to native HA via hydrolysis. Leaflets were characterized with respect to (1) bending stiffness, (2) hydrophilicity, (3) whole blood clotting, and (4) cell (platelet and leukocyte) adhesion under static conditions using fresh human blood. In vitro hemodynamic testing of prototype HA/LLDPE IPN PHVs was used to assess feasibility as functional HVs. Bending stiffness was not significantly different from natural fresh leaflets. HA/LLDPE IPNs were more hydrophilic than LLDPE controls. HA/LLDPE IPNs caused less whole blood clotting and reduced cell adhesion compared to the plain LLDPE control. Prototype PHVs made with HA/LLDPE IPNs demonstrated an acceptable regurgitation fraction of 4.77 ± 0.42%, and effective orifice area in the range 2.34 ± 0.5 cm2. These results demonstrate strong potential for IPNs between HA and polymers as future hemocompatible HV leaflets. Further studies are necessary to assess durability and calcification resistance.
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Affiliation(s)
- David A. Prawel
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Harold Dean
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Marcio Forleo
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Nicole Lewis
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Justin Gangwish
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO, USA
| | - Ketul C. Popat
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Lakshmi Prasad DASI
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Susan P. James
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
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123
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Edwards MB, Mclean J, Solomonidis S, Condon B, Gourlay T. In vitro assessment of the Lenz effect on heart valve prostheses at 1.5 T. J Magn Reson Imaging 2014; 41:74-82. [PMID: 24436215 DOI: 10.1002/jmri.24547] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 11/12/2013] [Indexed: 12/31/2022] Open
Abstract
PURPOSE Increasing numbers of patients with cardiac valve prostheses are being referred for magnetic resonance imaging (MRI) despite concerns about the potential for functional valve impedance due to Lenz forces. This study aims to determine, in vitro, the occurrence of Lenz forces on 9 heart valve prostheses at 1.5 T and assess the risk of impedance of valve function. MATERIALS AND METHODS A specially designed hydro-pneumatic system was used to record pressure changes across the valve indicative of any MR induced alteration in leaflet performance. Nine cardiac valve prostheses were exposed to the B0 field at 1.5 T. Each valve was advanced through the B0 field and continuous signals from high frequency pressure transducers were recorded and pressure drops across the valve were assessed using time correction superimposition. The delta p across the valve was assessed as a marker of any MRI induced alteration in leaflet performance. RESULTS All prostheses produced sinusoidal waveforms. Profiles were asymmetrical and there was no consistency in complex shape and valve type/sub-group. Irregularities in pressure profiles of 4 prostheses were detected indicating resistance of the occluder to the B0 field. CONCLUSION This study provides empirical evidence of the Lenz Effect on cardiac valve prostheses exposed to the MR B0 field causing functional valve impedance and increasing the risk of valvular regurgitation and reduced cardiac output. Thus, it is essential to consider the potential for the Lenz Effect when scanning cardiac valve implant patients in order to safeguard their wellbeing.
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124
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Mathematical Modelling of Peristaltic Pumping of Nano-Fluids. SIMULATION FOUNDATIONS, METHODS AND APPLICATIONS 2014. [DOI: 10.1007/978-3-319-05657-9_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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125
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Boggs T, Carroll R, Tran-Son-Tay R, Yamaguchi H, Al-Mousily F, DeGroff C. Blood Cell Adhesion on a Polymeric Heart Valve Leaflet Processed Using Magnetic Abrasive Finishing. J Med Device 2013. [DOI: 10.1115/1.4025853] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Polymeric heart valves have the potential to improve hemodynamic function without the complications associated with bioprosthetic and mechanical heart valves, but they have exhibited issues that need to be addressed including calcification, hydrolysis, low durability, and the adhesion of blood cells on the valves. These issues are attributed to the valves' material properties and surface conditions in addition to the hemodynamics. To overcome these issues, a new stentless, single-component trileaflet polymeric heart valve with engineered leaflet surface texture was designed, and prototypes were fabricated from a simple polymeric tube. The single-component structure features a trileaflet polymeric valve and conduit that are made of a single tube component to eliminate complications possibly caused by the interaction of multiple materials and components. This paper focuses on the leaflet surface modification and the effects of leaflet surface texture on blood cell adhesion to the leaflet surface. Silicone rubber was chosen as the working material. A magnetic abrasive finishing (MAF) process was used to alter the inner surface of the tubular mold in contact with the silicone leaflets during the curing process. It was hypothesized that the maximum profile height Rz of the mold surface should be smaller than the minimum platelet size of 1 μm to prevent platelets (1–3 μm in diameter) from becoming lodged between the peaks. Cell adhesion studies using human whole blood flushed at low shear stresses over leaflet surfaces with six different textures showed that adhesion of the platelets and red blood cells is greatly influenced by both surface roughness and lay. Leaflets replicated from MAF-produced mold surfaces consisting of short asperities smaller than 1 μm reduced blood cell adhesion and aggregation. Cell adhesion studies also found that either mold or leaflet surface roughness can be used as a measure of cell adhesion.
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Affiliation(s)
| | | | | | - Hitomi Yamaguchi
- e-mail: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611
| | - Faris Al-Mousily
- Department of Pediatrics, University of Florida, Gainesville, FL 32611
| | - Curt DeGroff
- Congenital Heart Center, University of Florida, Gainesville, FL 32611
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126
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Aydin E, Yapici F. A retrospective analysis of factors influencing re-operation in patients undergoing mechanical valve replacement. Cardiovasc J Afr 2013; 24:251-4. [PMID: 24217300 PMCID: PMC3807664 DOI: 10.5830/cvja-2013-044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/07/2013] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND We aimed to determine the possible factors leading to re-operation in patients undergoing mechanical valve replacement and to investigate the relationship between valvular thrombus formation and mean platelet volume. METHODS The medical records of 43 patients with mechanical valve implantation, who were admitted to the Department of Cardiovascular Surgery of Dr Siyami Ersek Thoracic and Cardiovascular Surgery Training and Research Hospital between 2000 and 2005 were analysed retrospectively. Data recorded included demographic characteristics, valve type, size and location, implantation position, warfarin use, INR level, additional cardiac intervention, presence of left atrial thrombus, valvular thrombus, pannus formation, perivalvular leak, left atrial aneurysm, platelet count and mean platelet volume (MPV), bleeding after the primary surgery and/or revision of surgery due to other reasons, valve protection, aortic root expansion, presence of valve calcification and infective endocarditis, pre- and postoperative rhythm pattern, brand name of prosthesis, distance of the patient's house from a cardiac surgery centre, and concomitant noncardiac systemic diseases. RESULTS Mean age was 49.3 years (range 19-78 years). Of the patients, 51% (n = 22) were males and 49% (n = 21) were females. The re-operation mortality was 11.6%. Age, gender, valve type, brand of valve prosthesis, and implantation position were not risk factors for re-operation. The MPV was higher and statistically significant in patients with valvular thrombus during re-operation (p < 0.001). MPV was determined to be an independent risk factor with 85% sensitivity and 87% specificity. CONCLUSION MPV and INR levels should be closely monitored when designing individualised postoperative medical treatment for patients undergoing heart valve re-operation.
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Affiliation(s)
- Ebuzer Aydin
- Department of Cardiovascular Surgery, Dr Siyami Ersek Thoracic and Cardiovascular Surgery Training and Research Hospital, Istanbul, Turkey
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127
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Nerem RM. Bioengineering and the cardiovascular system. Glob Cardiol Sci Pract 2013; 2013:29-36. [PMID: 24688999 PMCID: PMC3963728 DOI: 10.5339/gcsp.2013.5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 03/12/2013] [Indexed: 01/28/2023] Open
Abstract
The development of the modern era of bioengineering and the advances in our understanding of the cardiovascular system have been intertwined over the past one-half century. This is true of bioengineering as an area for research in universities. Bioengineering is ultimately the beginning of a new engineering discipline, as well as a new discipline in the medical device industry.
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Affiliation(s)
- Robert M Nerem
- Institute Professor Emeritus, Parker H. Petit Institute for Bioengineering and Bioscience Georgia Institute of Technology, Atlanta, GA 30332-0363, USA
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128
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Purely phase-encoded MRI of turbulent flow through a dysfunctional bileaflet mechanical heart valve. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2013; 27:227-35. [PMID: 24061612 DOI: 10.1007/s10334-013-0408-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Revised: 09/05/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022]
Abstract
OBJECT We have used a purely phase-encoded magnetic resonance imaging (MRI) technique, single-point ramped imaging with T1 enhancement (SPRITE), to investigate the steady, turbulent flow dynamics through a bileaflet mechanical heart valve (BMHV). MATERIALS AND METHODS We have measured in vitro the turbulent diffusivity and velocity downstream of the valve in two configurations (fully opened and partially opened), which mimic normal and dysfunctional operation. Our constant-time implementation of the MRI measurement is unusually robust to fast turbulent flows, and to artefacts caused by the pyrolytic carbon construction of the valve. RESULTS Turbulent diffusivity downstream of the normally functioning valve peaks at 1.05 × 10(-6)m(2)/s, while the turbulent diffusivity is higher downstream of the dysfunctional valve (peaking at 3.15 × 10(-6) m(2)/s) and is accompanied by a high-velocity fluid jet and re-circulating flow. The fluid jet is not along the centreline of the valve, as might be anticipated in conventional Doppler echocardiography measurements. CONCLUSION The nature of motion-sensitized SPRITE makes it unusually capable in turbulent flows and near to boundaries between different magnetic susceptibilities. These qualities have allowed us to compare the three-dimensional flow fields through normal and dysfunctional BMHVs.
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129
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Forleo M, Dasi LP. Effect of hypertension on the closing dynamics and Lagrangian blood damage index measure of the b-datum regurgitant jet in a bileaflet mechanical heart valve. Ann Biomed Eng 2013; 42:110-22. [PMID: 23975384 DOI: 10.1007/s10439-013-0896-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 08/14/2013] [Indexed: 11/27/2022]
Abstract
We hypothesize that the formation of the closing vortex and subsequent b-datum regurgitation jet in bileaflet mechanical heart valves is governed by the magnitude of the driving mean aortic pressure (MAP), and that this sensitivity does impact the blood damage index (BDI) corresponding to platelet activation and lysis. High spatial resolution time resolved (1 kHz) as well as phase locked particle image velocimetry techniques captured the dynamic leaflet closure and regurgitation jet of a model 25 mm St. Jude Medical BMHV. Cell trajectories were estimated using Lagrangian particle tracking analysis while the leaflet kinematics was quantified by tracking the leaflet tip-position throughout closure. The non-principal as well as principal shear stress loading histories along each cell trajectory revealed BDI for platelet activation and lysis as a function of cell initial position, release time-point, and blood pressure. Results show that the leaflet closing time reduces by roughly 10 ms, in response to an increase in MAP by 40 mmHg. We report that higher MAP leads to a stronger b-datum vortex and jet formation. Platelet activation BDI lowers with a higher MAP due to reduction in exposure times despite an increase in principal shear stress experienced. Platelet lysis BDI however increases with higher MAP. Maximum BDI may occur for cells initially in the b-datum zone during the onset of leaflet closure. Our results provide a better understanding of BDI of the regurgitant b-datum jet and sheds light on the potential importance of blood damage testing under hypertensive conditions.
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Affiliation(s)
- Marcio Forleo
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
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130
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Saikrishnan N, Gupta S, Yoganathan AP. Hemodynamics of the Boston Scientific Lotus™ Valve: An In Vitro Study. Cardiovasc Eng Technol 2013. [DOI: 10.1007/s13239-013-0163-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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131
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Le TB, Sotiropoulos F. Fluid-structure interaction of an aortic heart valve prosthesis driven by an animated anatomic left ventricle. JOURNAL OF COMPUTATIONAL PHYSICS 2013; 244:41-62. [PMID: 23729841 PMCID: PMC3667163 DOI: 10.1016/j.jcp.2012.08.036] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We develop a novel large-scale kinematic model for animating the left ventricle (LV) wall and use this model to drive the fluid-structure interaction (FSI) between the ensuing blood flow and a mechanical heart valve prosthesis implanted in the aortic position of an anatomic LV/aorta configuration. The kinematic model is of lumped type and employs a cell-based, FitzHugh-Nagumo framework to simulate the motion of the LV wall in response to an excitation wavefront propagating along the heart wall. The emerging large-scale LV wall motion exhibits complex contractile mechanisms that include contraction (twist) and expansion (untwist). The kinematic model is shown to yield global LV motion parameters that are well within the physiologic range throughout the cardiac cycle. The FSI between the leaflets of the mechanical heart valve and the blood flow driven by the dynamic LV wall motion and mitral inflow is simulated using the curvilinear immersed boundary (CURVIB) method [1, 2] implemented in conjunction with a domain decomposition approach. The computed results show that the simulated flow patterns are in good qualitative agreement with in vivo observations. The simulations also reveal complex kinematics of the valve leaflets, thus, underscoring the need for patient-specific simulations of heart valve prosthesis and other cardiac devices.
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Affiliation(s)
- Trung Bao Le
- Saint Anthony Falls Laboratory, Department of Civil Engineering, University of Minnesota, 2 Third Ave SE, Minneapolis, MN 55414
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132
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Kouhi E, Morsi YS. A parametric study on mathematical formulation and geometrical construction of a stentless aortic heart valve. J Artif Organs 2013; 16:425-42. [PMID: 23813273 DOI: 10.1007/s10047-013-0719-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 06/18/2013] [Indexed: 11/26/2022]
Abstract
This study presents a novel methodology for constructing an accurate geometrical model of a stentless aortic heart valve replacement (AVR). The main objective is to propose an optimized AVR model that can be used as an ideal scaffold for tissue engineering applications or a biocompatible prosthesis. Current techniques available for creating heart valve geometry, including leaflets, are very complicated and are not precise, due to the extensive use of various complicated parameters. This paper introduces an alternative design procedure that uses limited and effective numbers of controlling parameters to construct the whole valve including the sinus of valsalva. In doing so the hyperbolic curves for multithickness leaflets are used and a 3D elliptical formulation is incorporated for the surface geometry of the sinus of valsalva. Still, the feasibility and the precision of the mathematical method are established by performing standard deviation analysis on the constructed surfaces. The surface fitting residuals are found as low as error 0.2351 mm with standard deviation of 8.83e-5 over the commissural lines. Preliminary validation to the proposed AVR model performance is achieved by testing the generated AVR model under quasi static condition while obtaining the mesh independent setup. The numerical model showed a rapid response of the leaflets to the transvalvular pressure where adequate values of stress are measured over the commissural lines.
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Affiliation(s)
- Esfandyar Kouhi
- Biomechanics and Tissue Engineering Group, Faculty of Engineering & Industrial Sciences, Swinburne University of Technology, P.O Box 218, Hawthorn, VIC, 3122, Australia,
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Abstract
Heart valve prostheses carry a risk for thrombosis and require an antithrombotic strategy to prevent stroke, systemic embolism, and prosthetic valve thrombosis. Contemporary randomized trials to guide the clinician on the optimal anticoagulant treatment are scarce, and the validity of the historical data for current recommendations can be questioned in view of the changes in valve prostheses, the patient population, and antithrombotic therapies. This limited evidence from clinical trials translates into divergent recommendations from the different scientific societies on the optimal intensity of oral anticoagulation and on the indication for antiplatelet therapy. The availability of new antithrombotic agents and the unclear thrombotic risk of the currently used prostheses underscore the need to redefine antithrombotic treatment in patients with heart valve prostheses.
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134
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Huang HYS, Balhouse BN, Huang S. Application of simple biomechanical and biochemical tests to heart valve leaflets: implications for heart valve characterization and tissue engineering. Proc Inst Mech Eng H 2013. [PMID: 23185957 DOI: 10.1177/0954411912455004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A simple biomechanical test with real-time displacement and strain mapping is reported, which provides displacement vectors and principal strain directions during the mechanical characterization of heart valve tissues. The maps reported in the current study allow us to quickly identify the approximate strain imposed on a location in the samples. The biomechanical results show that the aortic valves exhibit stronger anisotropic mechanical behavior than that of the pulmonary valves before 18% strain equibiaxial stretching. In contrast, the pulmonary valves exhibit stronger anisotropic mechanical behavior than aortic valves beyond 28% strain equibiaxial stretching. Simple biochemical tests are also conducted. Collagens are extracted at different time points (24, 48, 72, and 120 h) at different locations in the samples. The results show that extraction time plays an important role in determining collagen concentration, in which a minimum of 72 h of extraction is required to obtain saturated collagen concentration. This work provides an easy approach for quantifying biomechanical and biochemical properties of semilunar heart valve tissues, and potentially facilitates the development of tissue engineered heart valves.
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Affiliation(s)
- Hsiao-Ying S Huang
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA.
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135
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Nawroth JC, Parker KK. Design standards for engineered tissues. Biotechnol Adv 2012; 31:632-7. [PMID: 23267860 DOI: 10.1016/j.biotechadv.2012.12.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 11/16/2022]
Abstract
Traditional technologies are required to meet specific, quantitative standards of safety and performance. In tissue engineering, similar standards will have to be developed to enable routine clinical use and customized tissue fabrication. In this essay, we discuss a framework of concepts leading towards general design standards for tissue-engineering, focusing in particular on systematic design strategies, control of cell behavior, physiological scaling, fabrication modes and functional evaluation.
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Affiliation(s)
- Janna C Nawroth
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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136
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Dimakopoulos Y, Bogaerds AC, Anderson PD, Hulsen MA, Baaijens FP. Direct numerical simulation of a 2D-stented aortic heart valve at physiological flow rates. Comput Methods Biomech Biomed Engin 2012; 15:1157-79. [DOI: 10.1080/10255842.2011.581238] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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137
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A Biocompatible Flow Chamber to Study the Hemodynamic Performance of Prosthetic Heart Valves. ASAIO J 2012; 58:470-80. [DOI: 10.1097/mat.0b013e31826140a2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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138
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Hockaday LA, Kang KH, Colangelo NW, Cheung PYC, Duan B, Malone E, Wu J, Girardi LN, Bonassar LJ, Lipson H, Chu CC, Butcher JT. Rapid 3D printing of anatomically accurate and mechanically heterogeneous aortic valve hydrogel scaffolds. Biofabrication 2012; 4:035005. [PMID: 22914604 DOI: 10.1088/1758-5082/4/3/035005] [Citation(s) in RCA: 371] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The aortic valve exhibits complex three-dimensional (3D) anatomy and heterogeneity essential for the long-term efficient biomechanical function. These are, however, challenging to mimic in de novo engineered living tissue valve strategies. We present a novel simultaneous 3D printing/photocrosslinking technique for rapidly engineering complex, heterogeneous aortic valve scaffolds. Native anatomic and axisymmetric aortic valve geometries (root wall and tri-leaflets) with 12-22 mm inner diameters (ID) were 3D printed with poly-ethylene glycol-diacrylate (PEG-DA) hydrogels (700 or 8000 MW) supplemented with alginate. 3D printing geometric accuracy was quantified and compared using Micro-CT. Porcine aortic valve interstitial cells (PAVIC) seeded scaffolds were cultured for up to 21 days. Results showed that blended PEG-DA scaffolds could achieve over tenfold range in elastic modulus (5.3±0.9 to 74.6±1.5 kPa). 3D printing times for valve conduits with mechanically contrasting hydrogels were optimized to 14 to 45 min, increasing linearly with conduit diameter. Larger printed valves had greater shape fidelity (93.3±2.6, 85.1±2.0 and 73.3±5.2% for 22, 17 and 12 mm ID porcine valves; 89.1±4.0, 84.1±5.6 and 66.6±5.2% for simplified valves). PAVIC seeded scaffolds maintained near 100% viability over 21 days. These results demonstrate that 3D hydrogel printing with controlled photocrosslinking can rapidly fabricate anatomical heterogeneous valve conduits that support cell engraftment.
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Affiliation(s)
- L A Hockaday
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, USA
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139
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Evans RG. Editorial update 2012. Clin Exp Pharmacol Physiol 2012. [DOI: 10.1111/j.1440-1681.2011.05646.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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140
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Leong J, Munnelly A, Liberio B, Cochrane L, Vyavahare N. Neomycin and carbodiimide crosslinking as an alternative to glutaraldehyde for enhanced durability of bioprosthetic heart valves. J Biomater Appl 2011; 27:948-60. [DOI: 10.1177/0885328211430542] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Glutaraldehyde cross-linked porcine aortic valves, referred to as bioprosthetic heart valves (BHVs), are often used in heart valve replacements. Glutaraldehyde does not stabilize glycosaminoglycans (GAGs) and they are lost during preparation, in vivo implantation, cyclic fatigue, and storage. We report that binding of neomycin, a hyaluronidase inhibitor, to the tissues with carbodiimide cross-linking improves GAG retention without reducing collagen and elastin stability. It also led to improved biomechanical properties. Neomycin carbodiimide cross-linking did not significantly reduce calcification in a rat subdermal implantation model when they were stored in formaldehyde after cross-linking. Removal of formaldehyde storage significantly reduced calcification.
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Affiliation(s)
- Joshua Leong
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Amy Munnelly
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Brianna Liberio
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Leonard Cochrane
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Naren Vyavahare
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
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141
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Comparison of unfractionated heparin, low-molecular-weight heparin, low-dose and high-dose rivaroxaban in preventing thrombus formation on mechanical heart valves: results of an in vitro study. J Thromb Thrombolysis 2011; 32:417-25. [DOI: 10.1007/s11239-011-0621-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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142
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Maizato MJ, Hayashida SA, Taniguchi FP, Higa OZ, Pitombo RN, Cestari IA, Leirner AA, Stolf NA. In Vitro and In Vivo Evaluation of Lyophilized Bioprosthetic Valve. Artif Organs 2011; 35:490-6. [DOI: 10.1111/j.1525-1594.2011.01261.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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143
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Leiria TLL, Lopes RD, Williams JB, Katz JN, Kalil RAK, Alexander JH. Antithrombotic therapies in patients with prosthetic heart valves: guidelines translated for the clinician. J Thromb Thrombolysis 2011; 31:514-22. [PMID: 21327503 PMCID: PMC3699194 DOI: 10.1007/s11239-011-0574-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Patients with prosthetic heart valves require chronic oral anticoagulation. In this clinical scenario, physicians must be mindful of the thromboembolic and bleeding risks related to chronic anticoagulant therapy. Currently, only vitamin K antagonists are approved for this indication. This paper reviews the main heart valve guidelines focusing on the use of oral anticoagulation in these patients.
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Affiliation(s)
- Tiago L. L. Leiria
- Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia, Porto Alegre, Brazil
| | - Renato D. Lopes
- Duke Clinical Research Institute, Division of Cardiology, Department of Medicine, Duke University Medical Center, Box 3850, Durham, NC 27710, UK
| | - Judson B. Williams
- Duke Clinical Research Institute, Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC, UK
| | - Jason N. Katz
- Division of Cardiology & Division of Pulmonary/Critical Care Medicine, University of North Carolina Center for Heart and Vascular Care, Chapel Hill, NC, UK
| | - Renato A. K. Kalil
- Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia, Porto Alegre, Brazil. Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
| | - John H. Alexander
- Duke Clinical Research Institute, Division of Cardiology, Department of Medicine, Duke University Medical Center, Box 3850, Durham, NC 27710, UK
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144
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Tissue engineering on matrix: future of autologous tissue replacement. Semin Immunopathol 2011; 33:307-15. [PMID: 21279358 DOI: 10.1007/s00281-011-0258-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 01/19/2011] [Indexed: 01/03/2023]
Abstract
Tissue engineering aims at the creation of living neo-tissues identical or close to their native human counterparts. As basis of this approach, temporary biodegradable supporter matrices are fabricated in the shape of a desired construct, which promote tissue strength and provide functionality until sufficient neo-tissue is formed. Besides fully synthetic polymer-based scaffolds, decellularized biological tissue of xenogenic or homogenic origin can be used. In a second step, these scaffolds are seeded with autologous cells attaching to the scaffold microstructure. In order to promote neo-tissue formation and maturation, the seeded scaffolds are exposed to different forms of stimulation. In cardiovascular tissue engineering, this "conditioning" can be achieved via culture media and biomimetic in vitro exposure, e.g., using flow bioreactors. This aims at adequate cellular differentiation, proliferation, and extracellular matrix production to form a living tissue called the construct. These living autologous constructs, such as heart valves or vascular grafts, are created in vitro, comprising a viable interstitium with repair and remodeling capabilities already prior to implantation. In situ further in vivo remodeling is intended to recapitulate physiological vascular architecture and function. The remodeling mechanisms were shown to be dominated by monocytic infiltration and chemotactic host-cell attraction leading into a multifaceted inflammatory process and neo-tissue formation. Key molecules of these processes can be integrated into the scaffold matrix to direct cell and tissue fate in vivo.
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145
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Affiliation(s)
- Muralidhar Padala
- Joseph B. Whitehead Department of Surgery, Division of Cardiothoracic Surgery, Emory University School of Medicine
| | - William Brent Keeling
- Joseph B. Whitehead Department of Surgery, Division of Cardiothoracic Surgery, Emory University School of Medicine
| | - Robert A. Guyton
- Joseph B. Whitehead Department of Surgery, Division of Cardiothoracic Surgery, Emory University School of Medicine
| | - Vinod H. Thourani
- Joseph B. Whitehead Department of Surgery, Division of Cardiothoracic Surgery, Emory University School of Medicine
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146
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Stanger O, Hammerer M, Datz L. Severe non-valve-related hemolytic anemia following aortic root replacement. Interact Cardiovasc Thorac Surg 2010; 11:832-4. [DOI: 10.1510/icvts.2010.245514] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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147
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Sirois E, Sun W. Computational evaluation of platelet activation induced by a bioprosthetic heart valve. Artif Organs 2010; 35:157-65. [PMID: 21083829 DOI: 10.1111/j.1525-1594.2010.01048.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is known that bioprosthetic heart valves (BHVs) have better hemodynamics and lower thromboembolic events compared with their mechanical counterparts; however, patients implanted with BHVs still face the potential of such complications. The risk of a clinical thromboembolism is on average 0.7% per year in patients with tissue valves in sinus rhythm. In this study, we developed a computational fluid dynamic (CFD) model of a BHV implanted in an aortic root and investigated the BHV-induced platelet activation using a damage accumulation model previously applied to mechanical valves. The CFD model was validated against published experimental data, including the flow velocity profile across the valve and the transvalvular pressure drop, and close matches were obtained. Hemodynamic performance measures such as flow velocity, turbulent kinetic energy, and wall shear stress were explored. Lagrangian particle tracking was used to calculate the extent of platelet activation for central bulk flow and flow in the vicinity of the leaflets. A peak flow of 2.22 m/s was observed at 40 msec after peak systole in the vicinity of a fold at the base of the leaflets. With the platelet activation expressed as 0-100% of activation threshold levels, mean damage on one pass was 2.489 × 10(-7)% and maximum damage on one pass was 8.778 × 10(-4)%. Our results suggested that the potential for BHV-induced platelet activation was low and that the leaflet's fully open geometry might play a role in the extent of blood element damage.
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Affiliation(s)
- Eric Sirois
- Tissue Mechanics Laboratory, Biomedical Engineering Program, University of Connecticut, Storrs, CT 06269-3139, USA
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148
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Mohammadi H, Mequanint K. Prosthetic aortic heart valves: modeling and design. Med Eng Phys 2010; 33:131-47. [PMID: 20971672 DOI: 10.1016/j.medengphy.2010.09.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 07/19/2010] [Accepted: 09/24/2010] [Indexed: 10/18/2022]
Abstract
Although heart valve replacement is among the most common cardiovascular surgical procedures, their outcome is often difficult to predict. One of the reasons is the design and choice of the materials used for the fabrication of the prostheses. This review paper describes the use of modeling techniques in prosthetic heart valve (HV) design and aims at the justification and development of a polymer based trileaflet mechanical heart valve (MHV). The closing/opening phase behavior of the bileaflet MHV was investigated. The potential problem of valve failure due to crack propagation in the brittle pyrolytic carbon leaflet was also discussed. These studies suggest that although bileaflet MHV performs satisfactorily, there are justifications for improvement. Since the native aortic HV is trileaflet and made of anisotropic and hyperelastic tissue, one possible approach to a better MHV design is based on our ability to closely mimic the natural geometry and biomaterial properties.
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Affiliation(s)
- Hadi Mohammadi
- The Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
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149
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Maegdefessel L, Linde T, Krapiec F, Hamilton K, Steinseifer U, van Ryn J, Raaz U, Buerke M, Werdan K, Schlitt A. In vitro comparison of dabigatran, unfractionated heparin, and low-molecular-weight heparin in preventing thrombus formation on mechanical heart valves. Thromb Res 2010; 126:e196-200. [DOI: 10.1016/j.thromres.2010.06.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 06/15/2010] [Accepted: 06/16/2010] [Indexed: 10/19/2022]
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150
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