Relevant bibliographies by topics / Heart valves

Academic literature on the topic 'Heart valves'

Author: Grafiati
Published: 4 June 2021
Last updated: 29 July 2024

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Journal articles on the topic "Heart valves"

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Cheema, Faisal, Mona Ascha, Mohammad Pervez, Ayesha Mannan, Alex Kossar, and Gianluca Polvani. "Patents and Heart Valve Surgery – III: Percutaneous Heart Valves." Recent Patents on Cardiovascular Drug Discovery 09, no. 999 (January 23, 2014): 1. http://dx.doi.org/10.2174/1574890109666140123121301.

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Wolkers, W. "Freeze-dried decellularized heart valves for heart valve replacement." Cryobiology 73, no. 3 (December 2016): 403. http://dx.doi.org/10.1016/j.cryobiol.2016.09.020.

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von Oppell, Ulrich O., and Peter Zilla. "Introduction: Contemporary Heart Valves Prosthetic Heart Valves: Why Biological?" Journal of Long-Term Effects of Medical Implants 11, no. 3-4 (2001): 9. http://dx.doi.org/10.1615/jlongtermeffmedimplants.v11.i34.20.

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Dalen, James E. "Valvular heart disease, infected valves and prosthetic heart valves." American Journal of Cardiology 65, no. 6 (February 1990): C29—C31. http://dx.doi.org/10.1016/0002-9149(90)90112-e.

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Ramaswamy, Sharan. "Preface: Heart Valves." Journal of Long-Term Effects of Medical Implants 25, no. 1-2 (2015): 1. http://dx.doi.org/10.1615/jlongtermeffmedimplants.2015011914.

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Ho, SiewYen. "The heart valves." Cardiology Plus 6, no. 1 (2021): 73. http://dx.doi.org/10.4103/2470-7511.312599.

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Frankel, William C., and Tom C. Nguyen. "Artificial Heart Valves." JAMA 325, no. 24 (June 22, 2021): 2512. http://dx.doi.org/10.1001/jama.2020.19936.

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Elliott, A. T., and W. H. Bain. "Stolen Heart Valves?" Scottish Medical Journal 32, no. 5 (October 1987): 138–39. http://dx.doi.org/10.1177/003693308703200506.

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A patient having had both aortic and mitral valves replaced complained of triggering shop security alarms, attributing the problem to the prosthetic valves. It was demonstrated that the valves were not the cause of the problem and the source identified.
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Starr, A., and G. L. Grunkemeier. "Prosthetic heart valves." Current Opinion in Cardiology 2, no. 5 (September 1987): 822–28. http://dx.doi.org/10.1097/00001573-198709000-00016.

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Jamieson, W. R. Eric. "Prosthetic heart valves." Current Opinion in Cardiology 4, no. 2 (April 1989): 264–68. http://dx.doi.org/10.1097/00001573-198904000-00014.

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Dissertations / Theses on the topic "Heart valves"

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Chan, Gene Yel. "Cryopreservation of porcine heart valves." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60420.pdf.

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Anstine, Lindsey J. "Valve cell dynamics in developing, mature, and aging heart valves." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1478692972995079.

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Bishop, Winona F. "Hydrodynamic performance of mechanical and biological prosthetic heart valves." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29461.

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One of the major achievements in cardiac surgery over the past 30 years has been the ability to replace severely diseased heart valves with prosthetic ones. The option of using prosthetic heart valves for the treatment of valvular diseases has improved and prolonged many lives. This is reflected in around 120,000 heart valve replacement operations carried out every year in North America alone to correct the cardiovascular problems of stenosis, insufficiency, regurgitation, etc. The development of artificial heart valves depends on reliable knowledge of the hemodynamic performance and physiology of the cardiovascular system in addition to a sound understanding, at the fundamental level, of the associated fluid mechanics. It is evident from the literature review that noninvasive measurements in a confined area of complex transient geometry, providing critical information relating to valve performance, are indeed scarce. This thesis presents results of an extensive test program aimed at measuring turbulence stresses, steady and transient velocity profiles and their decay downstream of the mitral valve. Three mechanical tilting disc-type heart valves (Björk-Shiley convexo- concave, Björk-Shiley monostrut, and Bicer-Val) and two biological tissue valves (Hancock II and Carpentier-Edwards supraannular) are studied. The investigation was carried out using a sophisticated and versatile cardiac simulator in conjunction with a highly sensitive, noninvasive, two-component three-beam laser doppler anemometer system. The study covers both the steady (valve fully open) and pulsatile (resting heart rate) flow conditions. The continuous monitoring of the parametric time histories revealed useful details of the complex flow as well as helped establish location and timing of the peak parameter values. In addition, orientation experiments are conducted on the mechanical valves in an attempt to reduce stresses by altering the position of the major orifice. The experiments suggest correlation between high stresses and orientation. Based on the the data, the following general conclusions can be made: (i) Hemodynamic test results should be presented in nondimensional form to render them independent of test facilities, flow velocities, size of models, etc. This would facilitate comparison of results by different investigators, using different facilities and test conditions. (ii) The valves tested showed very disturbed flow fields which generated high turbulent stresses presenting a possibility of thromboembolism and, perhaps, haemolysis. (iii) Implantation orientation of the valve significantly affect the mechanical prostheses flow field. The single vortex formation in the posterior orientation results in a reduction in stresses compared to the anterior configuration. (iv) The present results together with the earlier information on pressure drop and regurgitation provide a comprehensive and organized picture of the valve performance. (v) The information is fundamental to the improvement in valve design, and development of guidelines for test methodology and acceptable performance criteria for marketing of the valves.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Barsanti, Stephen. "Observations on the mechanical behaviour of polyurethane heart valves." Thesis, University of the West of Scotland, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265928.

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Reynolds, Karen Jane. "Acoustic monitoring of prosthetic heart valves." Thesis, University of Leicester, 1994. http://hdl.handle.net/2381/34209.

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The aim of the work presented in this thesis was to examine the possibility of detecting structural changes to an implanted prosthetic heart valve by spectral analysis of the sounds produced by the valve. On closure, mechanical heart valves produce a distinct sound as the occluder strikes the metal frame of the valve. Any change in the mechanical state of the valve will produce changes in the modes of vibration of the entire structure, causing the spectrum of the closing sounds to change. Initial recordings were made in a large tank of water providing ideal valve actuation and recording conditions. Results showed that all valves produce a stable averaged spectrum, and that each valve has a unique averaged spectrum. A digital filtering technique was developed whereby a baseline spectrum recorded from each valve is used for comparison with all subsequently recorded spectra from that valve. Using this technique, averaged spectra from individual valves were found to be highly reproducible. However, a minor structural alteration to a valve (added mass, or strut fracture) caused significant spectral changes, readily detected by digital filtering. To investigate the effect of a finite recording volume, recordings were made in a tank with dimensions approximating those of a human thorax. Standing waves generated by reverberations were clearly visible in the results. Structural changes to a valve were still detectable. Recordings were also made from prosthetic valves implanted in patients. To reduce sound distortion at the thoracic surface, recordings were made with the patient submerged in water. Results showed that reproducible averaged spectra could be obtained from implanted valves provided recording conditions were kept constant. The technique has not yet been developed to the point where it can be applied clinically. Nevertheless the technique shows promise as a method of screening patients at risk.
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Zhang, Yinxing. "Bioprosthetic heart valves : ultrastructure and calcification." Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/26921.

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Background: Due to the geographic distance between abattoirs and commercial valve plants delays between harvest and fixation usually range from 48 to 72 hours. In order to assess the pre-fixation tissue damage arising from the hypoxic period and the resulting calcific degeneration after implantation, we used an ultrastructural damage score and transmission electron microscopy. Materials and Methods: In a step by step manner, three major issues were clarified: 1) The degree of pre-fixation tissue damage was determined in the four most widely used commercially produced tissue heart valves. Since stentless bioprostheses represent the latest promising trend in the development of biological heart valves, stentless models of the following makes were compared: Baxter, Medtronic, St. Jude and Biocor. Due to the fact that the aortic wall component of these valves proved most resistant to all anticalcification treatments, aortic wall tissue stood in the centre of our analyses. 2) Subsequently, three main determinants of the fixation process namely: delay, temperature and fixative-concentration were varied with the goal of significantly improving the ultrastructural preservation of the bioprosthetic tissue. 3) Eventually, the influence of improved ultrastructural preservation on calcific degeneration was evaluated under in vivo conditions in the non-human primate and the rat model. Results: The comparison of the four most commonly used stentless bioprosthetic heart valves revealed a disturbing degree of tissue damage in all valves. Using a damage score from 1 to 21 (21 being the worst), aortic wall tissue of commercial valves ranged from 10 to 18 and that of leaflet tissue from 12 to 20. When fixation conditions were permutated, tissue damage could almost be abolished by immediate fixation (within 30 minutes of slaughter), low-temperature fixation(4°C) and high glutaraldehyde concentrations (> 1 %). Our in vivo experiments confirmed that commercially used fixation (delayed fixation, room-temperature and I ow concentrations of glutaraldehyde) with its concomitant high degree of tissue damage results in high levels of calcification. Apart from a distinctly improved calcification potential in ultrastructurally well preserved tissue, there was also an inverse correlation between tissue calcification and the concentration of glutaraldehyde used for fixation. Conclusion: We could demonstrate that commercially produced bioprosthetic heart valves uniformly show badly damaged tissue and that tissue damage contributes to the calcific degeneration of these valves. We were also able to determine ideal fixation conditions which in turn significantly reduced tissue calcification.
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Damen, Bas Stefaan, and bsdamen@hotmail com. "Design, Development, and Optimisation of a Culture Vessel System for Tissue Engineering Applications." Swinburne University of Technology. n/a, 2003. http://adt.lib.swin.edu.au./public/adt-VSWT20040512.125051.

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A Tissue Engineering (TE) approach to heart valve replacement has the aim of producing an implant that is identical to healthy tissue in morphology, function and immune recognition. The aim is to harvest tissue from a patient, establish cells in culture from this tissue and then use these cells to grow a new tissue in a desired shape for the implant. The scaffold material that supports the growth of cells into a desired shape may be composed of a biodegradable polymer that degrades over time, so that the final engineered implant is composed entirely of living tissue. The approach used at Swinburne University was to induce the desired mechanical and functional properties of tissue and is to be developed in an environment subjected to flow stresses that mimicked the haemodynamic forces that natural tissue experiences. The full attainment of natural biomechanical and morphological properties of a TE structure has not as yet been demonstrated. In this thesis a review of Tissue Engineering of Heart Valves (TEHVs) is presented followed by an assessment of biocompatible materials currently used for TEHVs. The thrust of the work was the design and development of a Bioreactor (BR) system, capable of simulating the corresponding haemodynamic forces in vitro so that long-term cultivation of TEHVs and/or other structures can be mimicked. A full description of the developed BR and the verification of its functionality under various physiological conditions using Laser Doppler Anemometry (LDA) are given. An analysis of the fluid flow and shear stress forces in and around a heart valve scaffold is also provided. Finally, preliminary results related to a fabricated aortic TEHV-scaffold and the developed cell culture systems are presented and discussed. Attempts to establish viable cell lines from ovine cardiac tissue are also reported.
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Gieseking, Elizabeth Robinson. "Control mechanism for the papillary muscles of the mitral valve : an In Vitro study." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/10912.

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Gallocher, Siobhain Lynn. "Durability Assessment of Polymer Trileaflet Heart Valves." FIU Digital Commons, 2007. http://digitalcommons.fiu.edu/etd/54.

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The durability of a polymer trileaflet valve is dependent on leaflet stress concentrations, so valve designs that reduce stress can, hypothetically, increase durability. Design aspects that are believed to contribute to reduced leaflet stress include stent flexibility, parabolic coaptation curvature, and leaflet anisotropy. With this in mind, the purpose of this investigation was to elucidate what specific combinations of these parameters promote optimal acute and long-term valve function. A combination of four stent designs, seven leaflet reinforcement materials, and three coaptation geometries were evaluated through a combination of experimentation and modeling. Static tensile and Poisson’s ratio tests and dynamic tensile fatigue testing were used to evaluate the individual leaflet components; and hydrodynamic testing and accelerated valve fatigue was used to assess complete valve prototypes. The two most successful designs included a 0.40 mm thick knit-reinforced valve with a fatigue life of 10.35 years, and a 0.20 mm thick knit-reinforced valve with a 28.9 mmHg decrease in pressure drop over the former. A finite element model was incorporated to verify the impact of the above-mentioned parameters on leaflet stress concentrations. Leaflet anisotropy had a large impact on stress concentrations, and matching the circumferential modulus to that of the natural valve showed the greatest benefit. Varying the radial modulus had minimal impact. Varying coaptation geometry had no impact, but stent flexibility did have a marked effect on the stress at the top of the commissure, where a completely rigid stent resulted in a higher peak stress than a flexible stent (E = 385 MPa). In conclusion, stent flexibility and leaflet anisotropy do effect stress concentrations in the SIBS trileaflet valve, but coaptation geometry does not. Regions of high stress concentrations were linked to failure locations in vitro, so a fatigue prediction model was developed from the S/N curves generated during dynamic tensile testing of the 0.20 mm knit-reinforced leaflets. Failure was predicted at approximately 400 million cycles (10 years) at the top of the commissure. In vitro fatigue of this valve showed failure initiation after approximately 167 million cycles (4.18 years), but it was related to a design defect that is subsequently being changed.
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Weind, Kirsten L. "Potential oxygenation routes of aortic heart valves." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58247.pdf.

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Books on the topic "Heart valves"

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Iaizzo, Paul A., Richard W. Bianco, Alexander J. Hill, and James D. St. Louis, eds. Heart Valves. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9.

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Iaizzo, Paul A., Tinen L. Iles, Massimo Griselli, and James D. St. Louis, eds. Heart Valves. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-25541-0.

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Love, Jack. Autologous tissue heart valves. Austin: R.G. Landes Co., 1993.

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Zabalgoitia, Miguel. Echocardiography of prosthetic heart valves. Austin: R.G. Landes Co., 1994.

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E, Dalen James, and Alpert Joseph S. 1942-, eds. Valvular heart disease. 2nd ed. Boston: Little, Brown, 1987.

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1932-, Dalen James E., and Alpert Joseph S, eds. Valvular heart disease. 2nd ed. Boston: Little, Brown, 1987.

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Institution of Mechanical Engineers (Great Britain) and Institution of Mechanical Engineers (Great Britain). Engineering in Medicine Section., eds. Heart valve engineering: Papers presented at a seminar organized by the Engineering in Medicine Group of the Institution of Mechanical Engineers and held at the Institution of Mechanical Engineers on 4-5 December 1986. London: Published by Mechanical Engineering Publications for the Institution of Mechanical Engineers, 1986.

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Carlos, Gomez-Duran, Reul George J, and St Jude Medical Inc, eds. Indications for heart valve replacement by age group. Boston: Kluwer Academic Publishers, 1989.

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H, Rahimtoola Shahbudin, ed. Valvular heart disease. Philadelphia: Current Medicine, 1997.

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1951-, Al Zaibag Muayed, and Gomez-Duran Carlos, eds. Valvular heart disease. New York: M. Dekker, 1994.

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Book chapters on the topic "Heart valves"

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Bateman, Michael G., Jason L. Quill, Alexander J. Hill, and Paul A. Iaizzo. "The Anatomy and Function of the Atrioventricular Valves." In Heart Valves, 3–25. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_1.

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Piazza, Nicolo, Darren Mylotte, and Giuseppe Martucci. "Transcatheter Aortic Valve Implantation." In Heart Valves, 227–60. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_10.

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Schmidt, Jillian B., and Robert T. Tranquillo. "Tissue-Engineered Heart Valves." In Heart Valves, 261–80. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_11.

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Kelley, Timothy A., Sal Marquez, and Carl F. Popelar. "In Vitro Testing of Heart Valve Substitutes." In Heart Valves, 283–320. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_12.

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Schendel, Michael J., and Carl F. Popelar. "Numerical Methods for Design and Evaluation of Prosthetic Heart Valves." In Heart Valves, 321–41. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_13.

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Ahlberg, Sarah E., Michael G. Bateman, Michael D. Eggen, Jason L. Quill, Eric S. Richardson, and Paul A. Iaizzo. "Animal Models for Cardiac Valve Research." In Heart Valves, 343–57. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_14.

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Bateman, Michael G., Alexander J. Hill, Jason L. Quill, Michael D. Eggen, Christopher D. Rolfes, and Paul A. Iaizzo. "The Use of Isolated Heart Models and Anatomic Specimens as Means to Enhance the Design and Testing of Cardiac Valve Therapies." In Heart Valves, 359–80. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_15.

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Howard, Stephen A., Michael G. Bateman, Timothy G. Laske, and Paul A. Iaizzo. "Successful Development and Regulatory Approval of Replacement Cardiac Valves." In Heart Valves, 381–402. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_16.

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Iaizzo, Jenna C., and Anna T. F. Lovas. "Clinical Trial Requirements for Cardiac Valves." In Heart Valves, 403–19. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_17.

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Bateman, Michael G., Jason L. Quill, Alexander J. Hill, and Paul A. Iaizzo. "The Anatomy and Function of the Semilunar Valves." In Heart Valves, 27–43. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-1-4614-6144-9_2.

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Conference papers on the topic "Heart valves"

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Kutting, Maximilian, Ute Urban, and Ulrich Steinseifer. "Anchoring percutaneous heart valves." In 2011 1st Middle East Conference on Biomedical Engineering (MECBME). IEEE, 2011. http://dx.doi.org/10.1109/mecbme.2011.5752063.

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Johansen, Peter, Tina S. Andersen, J. Michael Hasenkam, Hans Nygaard, and Peter K. Paulsen. "Mechanical heart valve cavitation in patients with bileaflet valves." In 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE, 2014. http://dx.doi.org/10.1109/embc.2014.6944910.

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Zadeh, Parnian Boloori, Hamid N.-Hashemi, Scott C. Corbett, and Ahmet U. Coskun. "Calcification of Trileaflet Polyurethane Heart Valve." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19486.

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Heart valve disease is a common type of cardiac disease that causes a large number of mortalities worldwide. Patients with severe heart valve problems are required to undergo heart valve replacement surgeries. Mechanical and bioprosthetic heart valves are the current available prostheses for patients in need of a heart valve replacement surgery. Mechanical heart valves are susceptible to thromboembolism and thrombosis and bioprosthetic valves have a limited life-span because of leaflet wear and calcification. Different polyurethane valves were suggested as an alternative material. However, prior results indicated that tested polyurethanes failed due to calcification. The mechanism for polyurethane calcification is not yet completely understood. Kou Imachi et al. [2], suggested that the calcification is due to entrapment of blood proteins and/or phospholipids in microgaps in the polymer and subsequent attraction of Ca ion, leading to formation of calcium phosphate (Ca3(PO4)2). Bisphosphonates (BP), which are considered to enhance the calcification resistance of polymers once covalently bonded to the material, indicated promising results in some studies. Focus of the present study is the trileaflet polyurethane valve, originally developed in the design of the AbioCor® replacement heart, and has demonstrated excellent durability and hemocompatibility in clinical evaluation. Over the past three years, this valve has been modified and its potential as a replacement valve have been studied [1]. Valve hemodynamic analysis showed that it is comparable to bioprosthetic valve in terms of fluid flow, pressure drop and regurgitation [1]. In order to ensure the suitability of the trileaflet polyurethane valve as a replacement valve its fatigue and calcification resistance are studied. The purpose of this paper is to simulate calcification of trileaflet polyurethane valves in an in vitro accelerated test and compare that with that of tissue valves. Furthermore the effect of bisphosphonate modified polyurethane on calcification is studied.
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Zhang, Di, Jiazhong He, Jianping Yao, Zhongkai Wu, and Minghui Du. "Spectral Analysis of Heart Sounds Produced by Disorder Mechanical Prosthetic Heart Valves." In 2009 2nd International Conference on Biomedical Engineering and Informatics. IEEE, 2009. http://dx.doi.org/10.1109/bmei.2009.5305803.

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Kuan, Yee Han, Vinh-Tan Nguyen, and Hwa Liang Leo. "Simulation of Bileaflet Mechanical Heart Valves Flow Dynamics." In Biomedical Engineering. Calgary,AB,Canada: ACTAPRESS, 2012. http://dx.doi.org/10.2316/p.2012.764-145.

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Nejadmalayeri, AliReza, Klaus Hoffmann, and Jean-François Dietiker. "Numerical Simulation of Blood Flow Through Heart Valves." In 45th AIAA Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2007. http://dx.doi.org/10.2514/6.2007-527.

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Cox, Martijn A. J., Jeroen Kortsmit, Niels J. B. Driessen, Carlijn V. C. Bouten, and Frank P. T. Baaijens. "Inverse Mechanical Characterization of Tissue Engineered Heart Valves." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192521.

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Over the last few years, research interest in tissue engineering as an alternative for current treatment and replacement strategies for cardiovascular and heart valve diseases has significantly increased. In vitro mechanical conditioning is an essential tool for engineering strong implantable tissues [1]. Detailed knowledge of the mechanical properties of the native tissue as well as the properties of the developing engineered constructs is vital for a better understanding and control of the mechanical conditioning process. The nonlinear and anisotropic behavior of soft tissues puts high demands on their mechanical characterization. Current standards in mechanical testing of soft tissues include (multiaxial) tensile testing and indentation tests. Uniaxial tensile tests do not provide sufficient information for characterizing the full anisotropic material behavior, while biaxial tensile tests are difficult to perform, and boundary effects limit the test region to a small central portion of the tissue. In addition, characterization of the local tissue properties from a tensile test is non-trivial. Indentation tests may be used to overcome some of these limitations. Indentation tests are easy to perform and when indenter size is small relative to the tissue dimensions, local characterization is possible. We have demonstrated that by recording deformation gradients and indentation force during a spherical indentation test the anisotropic mechanical behavior of engineered cardiovascular constructs can be characterized [2]. In the current study this combined numerical-experimental approach is used on Tissue Engineered Heart Valves (TEHV).
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Condurache, Alexandru Paul, Tobias Hahn, Ulrich G. Hofmann, Michael Scharfschwerdt, Martin Misfeld, and Til Aach. "Automatic measuring of quality criteria for heart valves." In Medical Imaging, edited by Josien P. W. Pluim and Joseph M. Reinhardt. SPIE, 2007. http://dx.doi.org/10.1117/12.710629.

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Bluestein, Danny, Jolyon Jesty, Adam E. Saltman, Irvin B. Krukenkamp, and Krishnamurthy Suresh. "Platelet Activation in Flow Past Mechanical Heart Valves." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/bed-23110.

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Abstract Numerical studies, in vitro, and in vivo measurements were conducted, aimed at quantifying free emboli formation and procoagulant properties of platelets induced by flow past mechanical heart valves (MHV). Pulsatile turbulent flow simulation was conducted past a St. Jude medical MHV in the aortic position, to study the effects of valve implantation technique on the thromboembolic potential of the valve. A misaligned valve with subannualarly sutured pledgets produced accelerating jet flow through the valve orifices and a wider wake of shed vortices. Shear stress histories of platelets along turbulent trajectories exposed the platelets to elevated shear stresses around the leaflets, leading them to entrapment within the shed vortices. In vitro platelet studies were conducted past the MHV mounted in a recirculation flow loop, by measuring the platelets ability to support the activation of acetylated human prothrombin by factor xa, which enables sequestering flow induced effects and quantification of the platelets activity state. The platelet activation state increased monotonically as a function of the recirculation time past the valve, as measured by the thrombin generation rates in the assay. Finally, platelet activity state measurements were conducted in vivo, from a sheep with an implanted MHV, showing marked increase of platelet activation after valve implantation.
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Lieber, Samuel C. "Validation of Bench Durability of Bioprosthetic Heart Valves." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/bed-23111.

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Abstract The number of heart valve replacements is increasing in the United States and worldwide due to aging of the population. This situation requires bioprosthetic heart valves with higher durability to reduce the rate of reoperation and the need for anticoagulation. However, introducing any improvement in the design of a heart valve requires ten years of validation in a clinical setup. A validated in-vitro fatigue testing system would significantly accelerate these innovations. The main objective of the proposed research is to: • Determine the dynamics of flow patterns and stresses in the vicinity of a bioprosthetic heart valve under pulsatile flow conditions. • Use the flow pattern information to validate an in-vitro fatigue testing system under physiological and accelerated conditions.
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Reports on the topic "Heart valves"

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Runjic, Frane, Andrija Matetic, Matjaz Bunc, Nikola Crncevic, and Ivica Kristic. Small Degenerated Surgical Bioprosthetic Valve should be Treated with SupraAnnular Valve-in-Valve Transcatheter Aortic Valve Replacement. Science Repository, December 2021. http://dx.doi.org/10.31487/j.jicoa.2021.04.02.

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Background: Patient-prothesis mismatch (PPM) is a serious potential complication following surgical aortic valve replacement (SAVR). If it develops, valve-in-valve transcatheter aortic valve replacement (TAVR) is a reasonable therapeutic option. However, there is low evidence on the management of small degenerated surgical bioprosthetic valves, not prone to balloon-valve fracture (BVF). Case Presentation: This case report presents a successful valve-in-valve TAVR in acute heart failure due to degenerative surgical bioprosthetic valve Trifecta (21 mm) that is not susceptible to BVF. Standard preparation for transfemoral TAVR with a self-expandable valve was conducted, including the over-the-wire pacing. Thereafter, a successful valve-in-valve primary implantation of the self-expanding, supra-annular valve Evolut R 26 (Medtronic™) has been achieved. Follow-up at 3 months showed mild paravalvular leak in the region with clinical and heart function improvements of the patient. Follow-up echocardiographic parameters showed the reduction of anterograde flow impairment and improved effective orifice area (~0.85 cm2/m2). Conclusion: In conclusion, supra-annular valve-in-valve TAVR is a potential therapeutic option for PPM of small degenerated surgical bioprosthetic valves which are not prone to BVF.
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Buhl, M. R., G. A. Clark, J. V. Candy, and G. H. Thomas. Detection of ``single-leg separated`` heart valves using statistical pattern recognition with the nearest neighbor classifier. Office of Scientific and Technical Information (OSTI), July 1993. http://dx.doi.org/10.2172/10177333.

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Buhl, M. R., G. A. Clark, J. V. Candy, and G. H. Thomas. Detection of ``single-leg separated`` heart valves using statistical pattern recognition with the nearest neighbor classifier. Revision 1. Office of Scientific and Technical Information (OSTI), December 1993. http://dx.doi.org/10.2172/10117041.

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Hendricks, Stefanie, Iryna Dykun, Bastian Balcer, Matthias Totzeck, Tienush Rassaf, and Amir A. Mahabadi. Higher BNP/NT-pro BNP levels stratify prognosis equally well in patients with and without heart failure – a meta-analysis with more than 89,000 patients. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, April 2022. http://dx.doi.org/10.37766/inplasy2022.4.0175.

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Review question / Objective: We performed a meta-analysis to investigate, whether the value of BNP/NT-proBNP as predictors of long-term prognosis differentiates in cohorts with and without heart failure. Condition being studied: The standardised cut-off levels for BNP and NT-proBNP that are currently used in clinical practice are based on the stratification of patients with heart failure. In patients without heart failure, however, relatively lower values are observed. This leads to the assumption that the prognosis for patients with BNP/NT-proBNP levels at the upper limit of the normal range might be worse than the prognosis for patients with BNP/NT-proBNP levels lower in the range, even if both are determined to be within the normal boundaries. However, a specific cut-off level of BNP/NT-proBNP for the prediction of prognosis in patients without heart failure has not yet been determined. Therefore, we performed a meta-analysis of existing studies investigating the value of BNP/NT-proBNP as a predictor of long-term prognosis in patients with heart failure and the general population.
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liao, xiaoqian, xingyu fan, ziyi wang, shumin huang, and zhixi hu. Prognostic value of heart-type fatty acid binding protein in heart failure: a systematic review protocol. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, March 2022. http://dx.doi.org/10.37766/inplasy2022.3.0126.

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Review question / Objective: (1)Can heart type fatty acid binding protein effectively predict the prognosis of patients with heart failure? (2)Is high expression of ear type fat acid binding protein associated with poor clinical outcomes in patients with heart failure? Condition being studied: Heart-type fatty acid binding protein (H-FABP) mainly exists in cardiomyocytes and is a potential biomarker of myocardial injury.However, the adverse consequences of heart failure have not been fully analyzed.Therefore, the purpose of this study was to comprehensively evaluate the correlation between H-FABP and the prognosis of heart failure through meta-analysis.
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Hern, P. J. Heat Treat of 3Z Valve Piston. Office of Scientific and Technical Information (OSTI), April 1999. http://dx.doi.org/10.2172/6020.

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Mullenhoff, C. Signal processing of Shiley heart valve data for fracture detection. Office of Scientific and Technical Information (OSTI), September 1993. http://dx.doi.org/10.2172/10190125.

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Mullenhoff, C. Signal processing of Shiley heart valve data for fracture detection. Office of Scientific and Technical Information (OSTI), April 1993. http://dx.doi.org/10.2172/10177267.

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Goff, Fraser, Jamie N. Gardner, Steven L. Reneau, Shari A. Kelley, Kirt A. Kempter, and John R. Lawrence. Geologic map of the Valles Caldera, Jemez Mountains, New Mexico. New Mexico Bureau of Geology and Mineral Resources, 2011. http://dx.doi.org/10.58799/gm-79.

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The Valles caldera, located in the heart of the Jemez Mountains in north-central New Mexico, is the world's premier example of a resurgent caldera, a giant circular volcano with an uplifted central floor and a near-perfect ring of roughly 15 postcaldera lava dome and flow eruptions.This new Valles caldera map and cross sections represent the cumulative research efforts of countless geologists over the past 40 years, and several state and federal agencies. GM-79 compiles detailed geologic mapping completed in the past eight years from parts of the nine 7.5-min USGS topographic quadrangles that encompass the caldera. More than 150 map units are described in detail. Also incorporated are new geochronologic data and recent refinements to nomenclature.
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Axelrod, M. C., G. A. Clark, and D. Scott. Classification of heart valve sounds from experiments in an anechoic water tank. Office of Scientific and Technical Information (OSTI), June 1999. http://dx.doi.org/10.2172/10788.

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