1
|
Shahriar SMS, McCarthy AD, Andrabi SM, Su Y, Polavoram NS, John JV, Matis MP, Zhu W, Xie J. Mechanically resilient hybrid aerogels containing fibers of dual-scale sizes and knotty networks for tissue regeneration. Nat Commun 2024; 15:1080. [PMID: 38316777 PMCID: PMC10844217 DOI: 10.1038/s41467-024-45458-x] [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: 09/24/2023] [Accepted: 01/24/2024] [Indexed: 02/07/2024] Open
Abstract
The structure and design flexibility of aerogels make them promising for soft tissue engineering, though they tend to come with brittleness and low elasticity. While increasing crosslinking density may improve mechanics, it also imparts brittleness. In soft tissue engineering, resilience against mechanical loads from mobile tissues is paramount. We report a hybrid aerogel that consists of self-reinforcing networks of micro- and nanofibers. Nanofiber segments physically entangle microfiber pillars, allowing efficient stress distribution through the intertwined fiber networks. We show that optimized hybrid aerogels have high specific tensile moduli (~1961.3 MPa cm3 g-1) and fracture energies (~7448.8 J m-2), while exhibiting super-elastic properties with rapid shape recovery (~1.8 s). We demonstrate that these aerogels induce rapid tissue ingrowth, extracellular matrix deposition, and neovascularization after subcutaneous implants in rats. Furthermore, we can apply them for engineering soft tissues via minimally invasive procedures, and hybrid aerogels can extend their versatility to become magnetically responsive or electrically conductive, enabling pressure sensing and actuation.
Collapse
Affiliation(s)
- S M Shatil Shahriar
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Eppley Institute for Research in Cancer and Allied Diseases, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Alec D McCarthy
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Syed Muntazir Andrabi
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Yajuan Su
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Navatha Shree Polavoram
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Johnson V John
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Mitchell P Matis
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Wuqiang Zhu
- Department of Cardiovascular Diseases, Physiology and Biomedical Engineering, Center for Regenerative Medicine, Mayo Clinic Arizona, Scottsdale, AZ, 85259, USA
| | - Jingwei Xie
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
- Department of Mechanical and Materials Engineering, University of Nebraska Lincoln, Lincoln, NE, 68588, USA.
| |
Collapse
|
2
|
How Strong Can We Pull? Critical Thresholds for Traction Forces on the Aortic Annulus: Measurements on Fresh Porcine Hearts. Medicina (B Aires) 2022; 58:medicina58081055. [PMID: 36013522 PMCID: PMC9415296 DOI: 10.3390/medicina58081055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/28/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022] Open
Abstract
Background and Objectives: Friable or infected tissue remains a challenge in surgical aortic valve replacement. We recently described the “Caput medusae” method, in which circumferential tourniquets temporarily secure the prosthesis and are then gently knotted. Tourniquets have been shown to develop significantly less force than knots. The current study investigates the critical threshold forces for tissue damage to the aortic annulus. Materials and Methods: In 14 fresh porcine hearts, the aortic valve leaflets were removed and several pledgeted sutures were placed along the annulus at defined locations. The hearts were mounted in a self-constructed device. Incremental traction force was applied to every suture and continuously recorded. The movement of each Teflon pledget was filmed with a high-speed camera. Forces at the moment of pledget “cut-in” as well as complete “tear-out” were determined from the recordings. Results: The average threshold force was determined 9.31 ± 6.04 N for cut-in and 20.41 ± 10.02 N for tear-out. Detailed analysis showed that the right coronary region had lower threshold forces than the other regions (4.77 ± 3.28 N (range, 1.67–12.75 N) vs. 10.67 ± 6.04 N (1.62–26.00 N) for cut-in and 10.67 ± 4.04 N (5.40–18.64 N) vs. 23.33 ± 9.42 N (9.22–51.23 N) for tear-out). The findings are discussed in conjunction with the knot and tourniquet forces from our previous study. Conclusions: Even in healthy tissue, moderate forces can reach a critical level at which a Teflon pledget will cut into the annulus, while a complete tear-out is unlikely. The right coronary portion is more susceptible to damage than the remaining regions. When compared to previous data, forces during manual knotting may exceed the critical cut-in level, while rubber tourniquets may provide a higher safety margin against tissue rupture.
Collapse
|
3
|
Deb N, Lacerda CMR. Valvular Endothelial Cell Response to the Mechanical Environment-A Review. Cell Biochem Biophys 2021; 79:695-709. [PMID: 34661855 DOI: 10.1007/s12013-021-01039-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 10/02/2021] [Indexed: 01/08/2023]
Abstract
Heart valve leaflets are complex structures containing valve endothelial cells, interstitial cells, and extracellular matrix. Heart valve endothelial cells sense mechanical stimuli, and communicate amongst themselves and the surrounding cells and extracellular matrix to maintain tissue homeostasis. In the presence of abnormal mechanical stimuli, endothelial cell communication is triggered in defense and such processes may eventually lead to cardiac disease progression. This review focuses on the role of mechanical stimuli on heart valve endothelial surfaces-from heart valve development and maintenance of tissue integrity to disease progression with related signal pathways involved in this process.
Collapse
Affiliation(s)
- Nandini Deb
- Jasper Department of Chemical Engineering, The University of Texas at Tyler, 3900 University Blvd, Tyler, 75799, TX, US
| | - Carla M R Lacerda
- Jasper Department of Chemical Engineering, The University of Texas at Tyler, 3900 University Blvd, Tyler, 75799, TX, US.
| |
Collapse
|
4
|
Singh G, Chanda A. Mechanical properties of whole-body soft human tissues: a review. Biomed Mater 2021; 16. [PMID: 34587593 DOI: 10.1088/1748-605x/ac2b7a] [Citation(s) in RCA: 93] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 09/29/2021] [Indexed: 11/11/2022]
Abstract
The mechanical properties of soft tissues play a key role in studying human injuries and their mitigation strategies. While such properties are indispensable for computational modelling of biological systems, they serve as important references in loading and failure experiments, and also for the development of tissue simulants. To date, experimental studies have measured the mechanical properties of peripheral tissues (e.g. skin)in-vivoand limited internal tissuesex-vivoin cadavers (e.g. brain and the heart). The lack of knowledge on a majority of human tissues inhibit their study for applications ranging from surgical planning, ballistic testing, implantable medical device development, and the assessment of traumatic injuries. The purpose of this work is to overcome such challenges through an extensive review of the literature reporting the mechanical properties of whole-body soft tissues from head to toe. Specifically, the available linear mechanical properties of all human tissues were compiled. Non-linear biomechanical models were also introduced, and the soft human tissues characterized using such models were summarized. The literature gaps identified from this work will help future biomechanical studies on soft human tissue characterization and the development of accurate medical models for the study and mitigation of injuries.
Collapse
Affiliation(s)
- Gurpreet Singh
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India
| | - Arnab Chanda
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India.,Department of Biomedical Engineering, All India Institute of Medical Sciences (AIIMS), Delhi, India
| |
Collapse
|
5
|
The precision of macroscale mechanical measurements is limited by the inherent structural heterogeneity of human stratum corneum. Acta Biomater 2021; 130:308-316. [PMID: 34087446 DOI: 10.1016/j.actbio.2021.05.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 05/18/2021] [Accepted: 05/20/2021] [Indexed: 12/18/2022]
Abstract
Biological tissues are structurally heterogenous mosaics at cellular and sub-cellular length scales. Some tissues, like the outermost layer of human skin, or stratum corneum (SC), also exhibit a rich topography of microchannels at larger mesoscopic length scales. Although this is well understood, modern studies continue to characterize the mechanical properties of biological tissues, including the SC, using macroscale techniques that assume these materials are homogenous in structure, thickness, and composition. Macroscale failure testing of SC is commonly associated with large sample to sample variability. We anticipate that microscale heterogeneities play an important role in defining the global mechanical response of the tissue. To evaluate the validity of the prevailing paradigm that macroscopic testing techniques can provide meaningful information about failure in soft heterogenous tissues, the macroscale work of fracture in isolated human SC samples is measured using conventional macroscale testing techniques and compared with the energy cost of creating new crack interfaces at the microscale, measured using a modified traction force microscopy technique. Results show that measured micro- and macroscale energy costs per unit crack path length are highly consistent. However, crack propagation is found to be guided by microscale topographical features in the tissue. This correlation reveals that macroscale mechanical sample to sample variability is caused by notable differences in crack propagation pathways. STATEMENT OF SIGNIFICANCE: Although designed to test homogeneous materials, macroscopic uniaxial tensometry is currently the gold standard for measuring the mechanical properties of biological tissues. All tissues, including human stratum corneum are structurally heterogeneous at the microscale and mechanical measurements are commonly highly variable, even for specimens from the same source. This study explores the fundamental causes of this disparity and evaluates the prevailing paradigm that macroscopic testing techniques can provide meaningful information about failure in soft heterogeneous tissues. Results conclude that the cause of large variability in mechanical work of fracture is due to inherent structural heterogeneities governing crack propagation pathways and altering the total crack length. Structural heterogeneities in tissue therefore limits the precision of macroscale biomechanical testing.
Collapse
|
6
|
Ma Z, Bao G, Li J. Multifaceted Design and Emerging Applications of Tissue Adhesives. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2007663. [PMID: 33956371 DOI: 10.1002/adma.202007663] [Citation(s) in RCA: 97] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/04/2020] [Indexed: 05/24/2023]
Abstract
Tissue adhesives can form appreciable adhesion with tissues and have found clinical use in a variety of medical settings such as wound closure, surgical sealants, regenerative medicine, and device attachment. The advantages of tissue adhesives include ease of implementation, rapid application, mitigation of tissue damage, and compatibility with minimally invasive procedures. The field of tissue adhesives is rapidly evolving, leading to tissue adhesives with superior mechanical properties and advanced functionality. Such adhesives enable new applications ranging from mobile health to cancer treatment. To provide guidelines for the rational design of tissue adhesives, here, existing strategies for tissue adhesives are synthesized into a multifaceted design, which comprises three design elements: the tissue, the adhesive surface, and the adhesive matrix. The mechanical, chemical, and biological considerations associated with each design element are reviewed. Throughout the report, the limitations of existing tissue adhesives and immediate opportunities for improvement are discussed. The recent progress of tissue adhesives in topical and implantable applications is highlighted, and then future directions toward next-generation tissue adhesives are outlined. The development of tissue adhesives will fuse disciplines and make broad impacts in engineering and medicine.
Collapse
Affiliation(s)
- Zhenwei Ma
- Department of Mechanical Engineering, McGill University, Montréal, QC, H3A 0C3, Canada
| | - Guangyu Bao
- Department of Mechanical Engineering, McGill University, Montréal, QC, H3A 0C3, Canada
| | - Jianyu Li
- Department of Mechanical Engineering, McGill University, Montréal, QC, H3A 0C3, Canada
- Department of Biomedical Engineering, McGill University, Montréal, QC, H3A 2B4, Canada
| |
Collapse
|
7
|
Litvinova K, Chernysheva M, Stegemann B, Leyva F. Autofluorescence guided welding of heart tissue by laser pulse bursts at 1550 nm. BIOMEDICAL OPTICS EXPRESS 2020; 11:6271-6280. [PMID: 33282489 PMCID: PMC7687929 DOI: 10.1364/boe.400504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/30/2020] [Accepted: 10/06/2020] [Indexed: 06/12/2023]
Abstract
Wound healing and other surgical technologies traditionally solved by suturing and stapling have recently been enhanced by the application of laser tissue welding. The usage of high energy laser radiation to anastomose tissues eliminates a foreign body reaction, reduces scar formation, and allows for the creation of watertight closure. In the current work, we show that an ultrafast pulsed fibre laser beam with 183 µJ·cm-2 energy fluence at 1550 nm provides successful welding of dissected chicken heart walls with the tensile strength of 1.03±0.12 kg·cm-2 equal to that of native tissue. The welding process was monitored employing fluorescence spectroscopy that detects the biochemical composition of tissues. We believe that fluorescence spectroscopy guided laser tissue welding is a promising approach for decreasing wound healing times and the avoiding risks of postoperative complications.
Collapse
Affiliation(s)
- Karina Litvinova
- Aston Medical School, Aston University, Aston Triangle, B4 7ET, Birmingham, UK
| | - Maria Chernysheva
- Leibniz Institute of Photonic Technology, Albert Einstein str 9, 07745, Jena, Germany
| | - Berthold Stegemann
- Aston Medical School, Aston University, Aston Triangle, B4 7ET, Birmingham, UK
| | - Francisco Leyva
- Aston Medical School, Aston University, Aston Triangle, B4 7ET, Birmingham, UK
- Cardiology Department, Queen Elizabeth Hospital, Mindelsohn Way, B15 2TH, Birmingham, UK
| |
Collapse
|
8
|
CMR and CT of the Patient With Cardiac Devices. JACC Cardiovasc Imaging 2019; 12:890-903. [DOI: 10.1016/j.jcmg.2018.09.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 08/24/2018] [Accepted: 09/13/2018] [Indexed: 01/15/2023]
|
9
|
Desai A, Vafaee T, Rooney P, Kearney JN, Berry HE, Ingham E, Fisher J, Jennings LM. In vitro biomechanical and hydrodynamic characterisation of decellularised human pulmonary and aortic roots. J Mech Behav Biomed Mater 2018; 79:53-63. [DOI: 10.1016/j.jmbbm.2017.09.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 09/12/2017] [Indexed: 12/31/2022]
|
10
|
Dahal S, Huang P, Murray BT, Mahler GJ. Endothelial to mesenchymal transformation is induced by altered extracellular matrix in aortic valve endothelial cells. J Biomed Mater Res A 2017; 105:2729-2741. [PMID: 28589644 DOI: 10.1002/jbm.a.36133] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 05/09/2017] [Accepted: 06/01/2017] [Indexed: 11/10/2022]
Abstract
Alterations in shear stress, mechanical deformation, extracellular matrix (ECM) composition and exposure to inflammatory conditions are known to cause endothelial to mesenchymal transformation (EndMT). This change in endothelial phenotype has only recently been linked to adult pathologies such as cancer progression, organ fibrosis, and calcific aortic valve disease; and its function in adult physiology, especially in response to tissue mechanics, has not been rigorously investigated. EndMT is a response to mechanical and biochemical signals that results in the remodeling of underlying tissues. In diseased aortic valves, glycosaminoglycans (GAGs) are present in the collagen-rich valve fibrosa, and are deposited near calcified nodules. In this study, in vitro models of early and late-stage valve disease were developed by incorporating the GAGs chondroitin sulfate (CS), hyaluronic acid, and dermatan sulfate into 3D collagen hydrogels with or without exposure to TGF-β1 to simulate EndMT in response to microenvironmental changes. High levels of CS induced the highest rate of EndMT and led to the most collagen I and GAG production by mesenchymally transformed cells, which indicates a cell phenotype most likely to promote fibrotic disease. Mesenchymal transformation due to altered ECM was found to depend on cell-ECM bond strength and extracellular signal-regulated protein kinases 1/2 signaling. Determining the environmental conditions that induce and promote EndMT, and the subsequent behavior of mesenchymally transformed cells, will advance understanding on the role of endothelial cells in tissue regeneration or disease progression. © 2017 Wiley Periodicals Inc. J Biomed Mater Res Part A: 105A: 2729-2741, 2017.
Collapse
Affiliation(s)
- Sudip Dahal
- Department of Biomedical Engineering, Binghamton University, Binghamton, New York, USA
| | - Peter Huang
- Department of Mechanical Engineering, Binghamton University, Binghamton, New York, USA
| | - Bruce T Murray
- Department of Mechanical Engineering, Binghamton University, Binghamton, New York, USA
| | - Gretchen J Mahler
- Department of Biomedical Engineering, Binghamton University, Binghamton, New York, USA
| |
Collapse
|
11
|
Pierce EL, Siefert AW, Paul DM, Wells SK, Bloodworth CH, Takebayashi S, Aoki C, Jensen MO, Gillespie MJ, Gorman RC, Gorman JH, Yoganathan AP. How Local Annular Force and Collagen Density Govern Mitral Annuloplasty Ring Dehiscence Risk. Ann Thorac Surg 2016; 102:518-26. [PMID: 27133454 DOI: 10.1016/j.athoracsur.2016.01.107] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 11/28/2015] [Accepted: 01/28/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Annuloplasty ring dehiscence is a well described mode of mitral valve repair failure. Defining the mechanisms underlying dehiscence may facilitate its prevention. METHODS Factors that govern suture dehiscence were examined with an ovine model. After undersized ring annuloplasty in live animals (n = 5), cyclic force (FC) that acts on sutures during cardiac contraction was measured with custom transducers. FC was measured at ten suture positions, throughout cardiac cycles with peak left ventricular pressure (LVPmax) of 100, 125, and 150 mm Hg. Suture pullout testing was conducted on explanted mitral annuli (n = 12) to determine suture holding strength at each position. Finally, relative collagen density differences at suture sites around the annulus were assessed by two-photon excitation fluoroscopy. RESULTS Anterior FC exceeded posterior FC at each LVPmax (eg, 2.8 ± 1.3 N versus 1.8 ± 1.2 N at LVPmax = 125 mm Hg, p < 0.01). Anterior holding strength exceeded posterior holding strength (6.4 ± 3.6 N versus 3.9 ± 1.6 N, p < 0.0001). On the basis of FC at LVPmax of 150 mm Hg, margin of safety before suture pullout was vastly higher between the trigones (exclusive) versus elsewhere (4.8 ± 0.9 N versus 1.9 ± 0.5 N, p < 0.001). Margin of safety exhibited strong correlation to collagen density (R(2) = 0.947). CONCLUSIONS Despite lower cyclic loading on posterior sutures, the weaker posterior mitral annular tissue creates higher risk of dehiscence, apparently because of reduced collagen content. Sutures placed atop the trigones are less secure than predicted, because of a combination of reduced collagen and higher overall rigidity in this region. These findings highlight the inter-trigonal tissue as the superior anchor and have implications on the design and implantation techniques for next-generation mitral prostheses.
Collapse
Affiliation(s)
- Eric L Pierce
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Andrew W Siefert
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Deborah M Paul
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Sarah K Wells
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Charles H Bloodworth
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Satoshi Takebayashi
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Chikashi Aoki
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Morten O Jensen
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Matthew J Gillespie
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Cardiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ajit P Yoganathan
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
| |
Collapse
|
12
|
Abstract
Prosthetic heart valve (PHV) dysfunction remains difficult to recognise correctly by two-dimensional (2D) transthoracic and transoesophageal echocardiography (TTE/TEE). ECG-triggered multidetector-row computed tomography (MDCT), 18-fluorine-fluorodesoxyglucose positron emission tomography including low-dose CT (FDG-PET) and three-dimensional transoesophageal echocardiography (3D-TEE) may have additional value. This paper reviews the role of these novel imaging tools in the field of PHV obstruction and endocarditis. For acquired PHV obstruction, MDCT is of additional value in mechanical PHVs to differentiate pannus from thrombus as well as to dynamically study leaflet motion and opening/closing angles. For biological PHV obstruction, additional imaging is not beneficial as it does not change patient management. When performed on top of 2D-TTE/TEE, MDCT has additional value for the detection of both vegetations and pseudoaneurysms/abscesses in PHV endocarditis. FDG-PET has no complementary value for the detection of vegetations; however, it appears more sensitive in the early detection of pseudoaneurysms/abscesses. Furthermore, FDG-PET enables the detection of metastatic and primary extra-cardiac infections. Evidence for the additional value of 3D-TEE is scarce. As clinical implications are major, clinicians should have a low threshold to perform additional MDCT in acquired mechanical PHV obstruction. For suspected PHV endocarditis, both FDG-PET and MDCT have complementary value.
Collapse
|
13
|
Siefert AW, Pierce EL, Lee M, Jensen MØ, Aoki C, Takebayashi S, Fernandez Esmerats J, Gorman RC, Gorman JH, Yoganathan AP. Suture forces in undersized mitral annuloplasty: novel device and measurements. Ann Thorac Surg 2014; 98:305-9. [PMID: 24996707 DOI: 10.1016/j.athoracsur.2014.02.036] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 02/10/2014] [Accepted: 02/17/2014] [Indexed: 10/25/2022]
Abstract
PURPOSE To demonstrate the first use of a novel technology for quantifying suture forces on annuloplasty rings to better understand the mechanisms of ring dehiscence. DESCRIPTION Force transducers were developed, attached to a size 24 Physio ring, and implanted in the mitral annulus of an ovine animal. Ring suture forces were measured after implantation and for cardiac cycles reaching peak left ventricular pressures (LVP) of 100, 125, and 150 mm Hg. EVALUATION After implantation of the undersized ring to the flaccid annulus, the mean suture force was 2.0±0.6 N. During cyclic contraction, the anterior ring suture forces were greater than the posterior ring suture forces at peak LVPs of 100 mm Hg (4.9±2.0 N vs 2.1±1.1 N), 125 mm Hg (5.4±2.3 N vs 2.3±1.2 N), and 150 mm Hg (5.7±2.4 N vs 2.4±1.1 N). The largest force was 7.4 N at 150 mm Hg. CONCLUSIONS The preliminary results demonstrate trends in annuloplasty suture forces and their variation with location and LVP. Future studies will significantly contribute to clinical knowledge by elucidating the mechanisms of ring dehiscence while improving annuloplasty ring design and surgical repair techniques.
Collapse
Affiliation(s)
- Andrew W Siefert
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Eric L Pierce
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Madonna Lee
- Gorman Cardiovascular Research Group, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Morten Ø Jensen
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Chikashi Aoki
- Gorman Cardiovascular Research Group, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Satoshi Takebayashi
- Gorman Cardiovascular Research Group, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joan Fernandez Esmerats
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ajit P Yoganathan
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
| |
Collapse
|
14
|
Wang R, Levi-Polyanchenko N, Morykwas M, Argenta L, Wagner WD. Novel nanofiber-based material for endovascular scaffolds. J Biomed Mater Res A 2014; 103:1150-8. [DOI: 10.1002/jbm.a.35267] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 06/17/2014] [Accepted: 06/25/2014] [Indexed: 12/15/2022]
Affiliation(s)
- Rui Wang
- Department of Plastic and Reconstructive Surgery; Wake Forest University School of Medicine; Medical Center Blvd Winston-Salem North Carolina 27157
- Virginia Tech - Wake Forest University School of Biomedical Engineering and Science; Medical Center Blvd Winston-Salem North Carolina 27157
| | - Nicole Levi-Polyanchenko
- Department of Plastic and Reconstructive Surgery; Wake Forest University School of Medicine; Medical Center Blvd Winston-Salem North Carolina 27157
- Virginia Tech - Wake Forest University School of Biomedical Engineering and Science; Medical Center Blvd Winston-Salem North Carolina 27157
| | - Michael Morykwas
- Department of Plastic and Reconstructive Surgery; Wake Forest University School of Medicine; Medical Center Blvd Winston-Salem North Carolina 27157
- Virginia Tech - Wake Forest University School of Biomedical Engineering and Science; Medical Center Blvd Winston-Salem North Carolina 27157
| | - Louis Argenta
- Department of Plastic and Reconstructive Surgery; Wake Forest University School of Medicine; Medical Center Blvd Winston-Salem North Carolina 27157
| | - William D. Wagner
- Department of Plastic and Reconstructive Surgery; Wake Forest University School of Medicine; Medical Center Blvd Winston-Salem North Carolina 27157
- Virginia Tech - Wake Forest University School of Biomedical Engineering and Science; Medical Center Blvd Winston-Salem North Carolina 27157
| |
Collapse
|
15
|
A histological and mechanical analysis of the cardiac lead-tissue interface: implications for lead extraction. Acta Biomater 2014; 10:2200-8. [PMID: 24434537 DOI: 10.1016/j.actbio.2014.01.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 11/19/2013] [Accepted: 01/07/2014] [Indexed: 11/21/2022]
Abstract
The major risks of pacemaker and implantable cardioverter defibrillator extraction are attributable to the fibrotic tissue that encases them in situ, yet little is known about the cellular and functional properties of this response. In the present research, we performed a histological and mechanical analysis of human tissue collected from the lead-tissue interface to better understand this process and provide insights for the improvement of lead design and extraction. The lead-tissue interface consisted of a thin cellular layer underlying a smooth, acellular surface, followed by a circumferentially organized collagen-rich matrix. 51.8±4.9% of cells were myofibroblasts via immunohistochemistry, with these cells displaying a similar circumferential organization. Upon mechanical testing, samples exhibited a triphasic force-displacement response consisting of a toe region during initial tensioning, a linear elastic region and a yield and failure region. Mean fracture load was 5.6±2.1N, and mean circumferential stress at failure was 9.5±4.1MPa. While the low cellularity and fibrotic composition of tissue observed herein is consistent with a foreign body reaction to an implanted material, the significant myofibroblast response provides a mechanical explanation for the contractile forces complicating extractions. Moreover, the tensile properties of this tissue suggest the feasibility of circumferential mechanical tissue disruption, similar to balloon angioplasty devices, as a novel approach to assist with lead extraction.
Collapse
|
16
|
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.
Collapse
|
17
|
Bronshtein T, Au-Yeung GCT, Sarig U, Nguyen EBV, Mhaisalkar PS, Boey FYC, Venkatraman SS, Machluf M. A mathematical model for analyzing the elasticity, viscosity, and failure of soft tissue: comparison of native and decellularized porcine cardiac extracellular matrix for tissue engineering. Tissue Eng Part C Methods 2013; 19:620-30. [PMID: 23265414 DOI: 10.1089/ten.tec.2012.0387] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The clinical success of tissue-engineered constructs commonly requires mechanical properties that closely mimic those of the human tissue. Determining the viscoelastic properties of such biomaterials and the factors governing their failure profiles, however, has proven challenging, although collecting extensive data regarding their tensile behavior is straightforward. The easily calculated Young's modulus remains the most reported mechanical measure, regardless of its limitations, even though single-relaxation-time (SRT) models can provide much more information, which remain scarce due to a lack of manageable tools for implementing these models. We developed an easy-to-use algorithm for applying the Zener SRT model and determining the elastic moduli, viscosity, and failure profiles of materials under different mechanical tests in a user-independent manner. The algorithm was validated on the data resulting from tensile tests on native and decellularized porcine cardiac tissue, previously suggested as a promising scaffold material for cardiac tissue engineering. This analysis yields new and more accurate measurements such as the elastic moduli and viscosity, the model's relaxation time, and information on the factors governing the materials' failure profiles. These measurements indicate that the viscoelasticity and strength of the decellularized acellular extracellular matrix (ECM) are similar to those of native tissue, although its elasticity and apparent viscosity are higher. Nonetheless, reseeding and culturing the ECM with mesenchymal stem cells was shown to partially restore the mechanical properties lost after decellularization. We propose this algorithm as a platform for soft-tissue analysis that can provide comparable and unbiased measures for characterizing viscoelastic biomaterials commonly used in tissue engineering.
Collapse
Affiliation(s)
- Tomer Bronshtein
- NTU-Technion Biomedical Labs, Materials and Science Engineering, Division of Materials Technology, Nanyang Technological University (NTU), Singapore
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Pham N, Zaitoun H, Mohammed TL, DeLaPena-Almaguer E, Martinez F, Novaro GM, Kirsch J. Complications of Aortic Valve Surgery: Manifestations at CT and MR Imaging. Radiographics 2012; 32:1873-92. [DOI: 10.1148/rg.327115735] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
19
|
Myers PO, Kalangos A, Panos A. Safety of magnetic resonance imaging in cardiac surgery patients: annuloplasty rings, septal occluders, and transcatheter valves. Ann Thorac Surg 2012; 93:1019; author reply 1019-20. [PMID: 22365008 DOI: 10.1016/j.athoracsur.2011.10.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 08/25/2011] [Accepted: 10/11/2011] [Indexed: 11/16/2022]
|
20
|
Chow MJ, Zhang Y. Changes in the Mechanical and Biochemical Properties of Aortic Tissue due to Cold Storage. J Surg Res 2011; 171:434-42. [DOI: 10.1016/j.jss.2010.04.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 03/05/2010] [Accepted: 04/08/2010] [Indexed: 10/19/2022]
|
21
|
Hundley WG, Bluemke DA, Finn JP, Flamm SD, Fogel MA, Friedrich MG, Ho VB, Jerosch-Herold M, Kramer CM, Manning WJ, Patel M, Pohost GM, Stillman AE, White RD, Woodard PK. ACCF/ACR/AHA/NASCI/SCMR 2010 expert consensus document on cardiovascular magnetic resonance: a report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents. J Am Coll Cardiol 2010; 55:2614-62. [PMID: 20513610 PMCID: PMC3042771 DOI: 10.1016/j.jacc.2009.11.011] [Citation(s) in RCA: 450] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
22
|
Hundley WG, Bluemke DA, Finn JP, Flamm SD, Fogel MA, Friedrich MG, Ho VB, Jerosch-Herold M, Kramer CM, Manning WJ, Patel M, Pohost GM, Stillman AE, White RD, Woodard PK. ACCF/ACR/AHA/NASCI/SCMR 2010 expert consensus document on cardiovascular magnetic resonance: a report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents. Circulation 2010; 121:2462-508. [PMID: 20479157 PMCID: PMC3034132 DOI: 10.1161/cir.0b013e3181d44a8f] [Citation(s) in RCA: 232] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
23
|
Walraevens J, Willaert B, De Win G, Ranftl A, De Schutter J, Sloten JV. Correlation between compression, tensile and tearing tests on healthy and calcified aortic tissues. Med Eng Phys 2008; 30:1098-104. [DOI: 10.1016/j.medengphy.2008.01.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 09/12/2007] [Accepted: 01/30/2008] [Indexed: 11/27/2022]
|
24
|
Levine GN, Gomes AS, Arai AE, Bluemke DA, Flamm SD, Kanal E, Manning WJ, Martin ET, Smith JM, Wilke N, Shellock FS. Safety of magnetic resonance imaging in patients with cardiovascular devices: an American Heart Association scientific statement from the Committee on Diagnostic and Interventional Cardiac Catheterization, Council on Clinical Cardiology, and the Council on Cardiovascular Radiology and Intervention: endorsed by the American College of Cardiology Foundation, the North American Society for Cardiac Imaging, and the Society for Cardiovascular Magnetic Resonance. Circulation 2007; 116:2878-91. [PMID: 18025533 DOI: 10.1161/circulationaha.107.187256] [Citation(s) in RCA: 311] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Advances in magnetic resonance (MR) imaging over the past 2 decades have led to MR becoming an increasingly attractive imaging modality. With the growing number of patients treated with permanent implanted or temporary cardiovascular devices, it is becoming ever more important to clarify safety issues in regard to the performance of MR examinations in patients with these devices. Extensive, although not complete, ex vivo, animal, and clinical data are available from which to generate recommendations regarding the safe performance of MR examination in patients with cardiovascular devices, as well as to ascertain caveats and contraindications regarding MR examination for such patients. Safe MR imaging involves a careful initial patient screening, accurate determination of the permanent implanted or temporary cardiovascular device and its properties, a thoughtful analysis of the risks and benefits of performing the examination at that time, and, when indicated, appropriate physician management and supervision. This scientific statement is intended to summarize and clarify issues regarding the safety of MR imaging in patients with cardiovascular devices.
Collapse
|
25
|
D'Avenio G, Canese R, Podo F, Grigioni M. A novel method for measuring the torque on implantable cardiovascular devices in MR static fields. J Magn Reson Imaging 2007; 26:1368-74. [PMID: 17969137 DOI: 10.1002/jmri.21146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To propose a novel quantitative method for measuring the torque acting on mechanical heart valve prostheses subjected to a high static magnetic field in a MR scanner. MATERIALS AND METHODS Torque measurements were performed with a torsion balance, implemented with a copper wire. The reaction torque exerted by the static magnetic field on the device was measured optically from the deflection angle of a laser beam spot on a graduate scale. Three different types of mechanical valves (two bileaflet and one monoleaflet) were tested at different locations of a small bore 4.7 tesla system. RESULTS The method proved to be particularly sensitive (detectability limit lower than 10(-6) N x m), reliable and yielded quantitative reproducible results. The equivalent force of the torque measured for the three valves was at least 10(3)-fold lower than the force exerted by the beating heart. CONCLUSION The proposed method provides a quantitative evaluation of the torque induced on prosthetic device by a MR scanner operating at high magnetic field.
Collapse
Affiliation(s)
- Giuseppe D'Avenio
- Department of Technology and Health, Istituto Superiore di Sanità, Rome, Italy
| | | | | | | |
Collapse
|
26
|
Abstract
Given the advances of MRI and cardiovascular technology, it is becoming increasingly likely that a patient with a cardiovascular device will be a candidate for an MRI procedure. However, many cardiac devices are currently considered to be contraindicated in the MR environment. This may prove to be a significant public health problem as many patients in need of MRI are denied the procedure because of the presence of a cardiovascular device. However, research studies have shown that with proper precautions and technique patients with cardiac devices can undergo successful MRI safely on the current platforms.
Collapse
Affiliation(s)
- Edward T Martin
- Cardiovascular Magnetic Resonance, Oklahoma Heart Institute, 9228 S. Mingo Road, Tulsa, OK 74133, USA.
| | | |
Collapse
|