Download or read book Mechanical Properties of Arteries written by Jan-Lucas Gade and published by Linköping University Electronic Press. This book was released on 2019-08-29 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this Licentiate of Engineering thesis, a method is proposed that identi?es the mechanical properties of arteries in vivo. The mechanical properties of an artery are linked to the development of cardiovascular diseases. The possibility to identify the mechanical properties of an artery inside the human body could, thus, facilitate disease diagnostization, treatment and monitoring. Supplied with information obtainable in the clinic, typically limited to time- resolved pressure-radius measurement pairs, the proposed in vivo parameter identi- ?cation method calculates six representative parameters by solving a minimization problem. The artery is treated as a homogeneous, incompressible, residual stress- free, thin-walled tube consisting of an elastin dominated matrix with embedded collagen ?bers referred to as the constitutive membrane model. To validate the in vivo parameter identi?cation method, in silico arteries in the form of ?nite element models are created using published data for the human abdominal aorta. With these in silico arteries which serve as mock experiments with pre-de?ned material parameters and boundary conditions, in vivo-like pressure-radius data sets are generated. The mechanical properties of the in silico arteries are then determined using the proposed parameter identi?cation method. By comparing the identi?ed and the pre-de?ned parameters, the identi?cation method is quantitatively validated. The parameters for the radius of the stress-free state and the material constant associated with elastin show high agreement in case of healthy arteries. Larger di?erences are obtained for the material constants associated with collagen, and the largest discrepancy occurs for the in situ axial prestretch. For arteries with a pathologically small elastin content, incorrect parameters are identi?ed but the presence of a diseased artery is revealed by the parameter identi?cation method. Furthermore, the identi?ed parameters are used in the constitutive membrane model to predict the stress state of the artery in question. The stress state is thereby decomposed into an isotropic and an anisotropic component which are primarily associated with the elastin dominated matrix and the collagen ?bers, respectively. In order to assess the accuracy of the predicted stress, it is compared to the known stress state of the in silico arteries. The comparison of the predicted and the in silico decomposed stress states show a close agreement for arteries exhibiting a low transmural stress gradient. With increasing transmural stress gradient the agreement deteriorates. The proposed in vivo parameter identi?cation method is capable of identifying adequate parameters and predicting the decomposed stress state reasonably well for healthy human abdominal aortas from in vivo-like data. In diesem Lizentiat der Ingenieurwissenschaften wird eine Methode zur Identifikation der mechanischen Eigenschaften von Arterien in vivo vorgestellt. Die mechanischen Eigenschaften einer Arterie sind mit der Ausbildung kardiovaskulärer Krankheiten verknüpft und deren Identifikation hat daher das Potenzial die Diagnose, die Behandlung und die Überwachung dieser Krankheiten zu verbessern. Basierend auf klinisch möglichen Messungen, die üblicherweise auf ein zeitaufgelöstes Druck-Radiussignal limitiert sind, werden sechs repräsentative Parameter durch Lösen eines Minimierungsproblems berechnet. Die sechs Parameter sind dabei die Eingangsparameter des zur Hilfe gezogenen konstitutiven Schalenmodells welches eine Arterie als eine homogene, inkompressible, restspannungsfreie und dünnwandige Röhre beschreibt. Weiterhin wird angenommen, dass die Arterienwand aus einer elastindominierten Matrix mit eingebetteten Kollagenfasern besteht. Um die in vivo Parameteridentifikationsmethode zu validieren, werden in silico Arterien in Form von Finite Elemente Modellen erstellt. Diese in silico Arterien beruhen auf publizierten Materialparametern der menschlichen Abdominalaorta und dienen als Pseudoexperimente mit vordefinierten mechanischen Eigenschaften und Randbedingungen. Mit diesen Arterien werden in vivo-ähnliche Druck-Radiussignale erstellt und anschliesend werden ihre mechanischen Eigenschaften mit Hilfe der Parameteridentifikationsmethode bestimmt. Der Vergleich der identifizierten und der vordefinierten Parameter ermöglicht die quantitative Validierung der Methode. Die Parameter des spannungsfreien Radius und der Materialkonstanten für Elastin weisen hohe Übereinstummung im Falle gesunder Arterien auf. Die Abweichung der Materialkonstanten für Kollagen sind etwas gröser und der gröste Unterschied tritt beim axialen in situ Stretch auf. Für Arterien mit einem pathologisch geringen Elastinbestandteil werden falsche Parameter identifiziert, wobei die Parameteridentifikationsmethode eine krankhafte Arterie offenlegt. Weiterhin werden mit Hilfe der identifizierten Parameter und des konstitutiven Schalenmodells der Spannungszustand in der Arterienwand berechnet. Dieser ist dabei aufgeteilt in einen isotropen und einen anisotropen Anteil. Der isotrope Anteil wird mit der elastindomierten Matrix und der anisotrope Anteil mit den Kollagenfasern verknüpft. Um die Genauigkeit des berechneten Spannungszustandes beurteilen zu können, wird dieser mit dem Zustand in den in silico Arterien verglichen. Im Fall von Arterien, die einen geringen transmuralen Spannungsgradienten aufweisen, entspricht der berechnete Spannungszustand dem in silico Zustand. Mit zunehmendem transmuralen Spannungsgradienten lässt die Übereinstimmung nach. Für die gesunde menschliche Abdominalaorta ist die entwickelte in vivo Parameteridentifikationsmethode in der Lage, basierend auf in vivo-ähnlichen Messsignalen, adäquate Parameter zu identifizieren und einen zufriedenstellenden Spannungszustand zu berechnen. I denna licentiatavhandling föreslås en metod för att identifiera mekaniska egenskaper hos artärer in vivo. De mekaniska egenskaperna är kopplade till utvecklingen av hjärt-kärlsjukdomar, och möjligheten att identifiera dessa egenskaper skulle således kunna underlätta diagnostisering, behandling och uppföljning av dessa sjukdomar. Den förslagna metoden använder kliniskt mätbara tryck-radie-signaler och löser ett minimeringsproblem för att bestämma sex parametrar som beskriver kärlets mekaniska egenskaper. Artären modelleras som ett homogent, inkompressibelt och spänningsfritt tunnväggigt rör där kärlväggen utgörs av en elastindominerad matris armerad med inbäddade kollagenfibrer. För att validera parameteridentifieringen skapas en uppsättning representativa, virtuella artärer med hjälp av finita element. Dessa in silico-artärer baseras på publicerade data för mänsklig bukaorta och används för att generera fiktiva tryckradie-signaler vilka sedan matas in i den förslagna modellen. Genom att parametrar och randvillkor för in silico-artärerna är kända fungerar dessa som en kontroll mot vilka resultatet från parameteridentifieringen kan jämföras. Parametrarna som beskriver den icke trycksatta radien och den elastindominerade matrisen visar god överensstämmelse med de in silico-artärerna för friska kärl. Större diskrepans erhålls för de parametrar som associeras med kollagenet, och den största avvikelsen erhålls för den parameter som beskriver den axiella försträckningen. För artärer med patologiskt lågt elastininnehåll identifieras felaktiga parametrar, men resultatet avslöjar ändå tydligt en sjuk artär. De identifierade parametrarna har också använts för att jämföra spänningstillst åndet i membranmodellen och in silico-artäreren. Spänningstillståndet har delats upp i en isotrop och en anisotrop komponent svarande mot, i huvudsak, den elastindominerade matrisen samt kollagenfibrerna. Resultatet visar en mycket god överensstämmelse för bägge komponenterna hos in silico-artärer med låg spänningsgradient genom väggen. Med ökande spänningsgradient försämras dock överensstämmelsen. Resultatet visar att den förslagna metoden är kapabel att identifiera adekvata parametrar och att förutsäga spänningskomponenterna i en frisk aorta.

Download or read book Mechanical Properties of Arteries written by Jan-Lucas Gade and published by Linköping University Electronic Press. This book was released on 2021-01-27 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, a method is proposed that identifies the mechanical properties of arteries in vivo. The mechanical properties of an artery are linked to the development of cardiovascular diseases. The possibility to identify the mechanical properties of an artery inside the human body could, thus, facilitate disease diagnostization, treatment and monitoring. Supplied with information obtainable in the clinic, typically limited to time-resolved pressure-radius measurement pairs, the proposed in vivo parameter identification method solves a non-convex minimization problem to determine parameters related to the mechanical properties of the blood vessel. The artery is treated as a homogeneous, incompressible, residual stress-free, thin-walled tube consisting of an elastin dominated matrix with embedded collagen fibers. To validate the in vivo parameter identification method, in silico arteries in the form of finite element models are created using published data for the human abdominal aorta. With these in silico arteries which serve as mock experiments with pre-defined material parameters and boundary conditions, in vivo-like pressure-radius data sets are generated. The mechanical properties of the in silico arteries are then determined using the proposed parameter identification method. By comparing the identified and the pre-defined parameters, the identification method is quantitatively validated and it is shown that the parameters agree well for healthy arteries. Furthermore, the identified parameters are used to compare the stress state in the arterial model and in the in silico arteries. The stress state is thereby decomposed into an isotropic and an anisotropic component which are primarily associated with the elastin dominated matrix and the collagen fibers, respectively. The comparison of the decomposed stress states shows a close agreement for arteries exhibiting a physiological stress gradient. Another important aspect is the identification of parameters by solving a non-convex minimization problem. The non-convexity of the problem implies that incorrect parameter values, corresponding to local minima, may be found when common gradient-based solution techniques are employed. A problem-specific global algorithm based on the branch-and-bound method is, therefore, created which ensures that the global minimum and accordingly the correct parameters are obtained. It turns out that the gradient-based solution technique identifies the correct parameters if certain requirements are met, among others the use of the heuristic multi-start method. In a last step, the in vivo parameter identification method is extended to also identify parameters related to smooth muscle contraction. To prevent an overparameterization caused by the increased number of model parameters, the model is simultaneously fit to clinical data measured during three different arterial conditions: basal; constricted; and dilated. Despite the simple contraction model the extended method fits the clinical data well. Finally, in this dissertation it is shown that the proposed in vivo parameter identification method identifies the mechanical properties of arteries well. An open question for future research is how this method can be applied in a clinical setting to facilitate cardiovascular disease diagnostization, treatment and monitoring.

Download or read book Mechanical Properties of Arteries written by Philip Boone Dobrin and published by . This book was released on 1968 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biomechanics of Soft Tissue in Cardiovascular Systems written by Gerhard A. Holzapfel and published by Springer. This book was released on 2014-05-04 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is written by leading experts in the field presenting an up-to-date view of the subject matter in a didactically sound manner. It presents a review of the current knowledge of the behaviour of soft tissues in the cardiovascular system under mechanical loads, and the importance of constitutive laws in understanding the underlying mechanics is highlighted. Cells are also described together with arteries, tendons and ligaments, heart, and other biological tissues of current research interest in biomechanics. This includes experimental, continuum mechanical and computational perspectives, with the emphasis on nonlinear behaviour, and the simulation of mechanical procedures such as balloon angioplasty.

Download or read book A Method of Determining the Mechanical Properties of Arteries in Vivo written by Frank Paul Primiano and published by . This book was released on 1963 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Biaxial Mechanical Properties of Arteries written by James Lloyd Hickey and published by . This book was released on 1979 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Static Mechanical Properties of Arteries and Their Replacements written by Daniel Nahon and published by . This book was released on 1986 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Equipment for Measurement of Mechanical Properties of Arteries written by Raymond Peter Vito and published by . This book was released on 1979 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Innovations in Biomedical Engineering written by Marek Gzik and published by Springer Nature. This book was released on 2022-05-31 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the latest developments in the field of biomedical engineering and includes practical solutions and strictly scientific considerations. The development of new methods of treatment, advanced diagnostics or personalized rehabilitation requires close cooperation of experts from many fields, including, among others, medicine, biotechnology and finally biomedical engineering. The latter, combining many fields of science, such as computer science, materials science, biomechanics, electronics not only enables the development and production of modern medical equipment, but also participates in the development of new directions and methods of treatment. The presented monograph is a collection of scientific papers on the use of engineering methods in medicine. The topics of the work include both practical solutions and strictly scientific considerations expanding knowledge about the functioning of the human body. We believe that the presented works will have an impact on the development of the field of science, which is biomedical engineering, constituting a contribution to the discussion on the directions of development of cooperation between doctors, physiotherapists and engineers. We would also like to thank all the people who contributed to the creation of this monograph—both the authors of all the works and those involved in technical works.

Download or read book Biomechanics written by Y. C. Fung and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 443 pages. Available in PDF, EPUB and Kindle. Book excerpt: The motivation for writing aseries ofbooks on biomechanics is to bring this rapidly developing subject to students of bioengineering, physiology, and mechanics. In the last decade biomechanics has become a recognized disci pline offered in virtually all universities. Yet there is no adequate textbook for instruction; neither is there a treatise with sufficiently broad coverage. A few books bearing the title of biomechanics are too elementary, others are too specialized. I have long feIt a need for a set of books that will inform students of the physiological and medical applications of biomechanics, and at the same time develop their training in mechanics. We cannot assume that all students come to biomechanics already fully trained in fluid and solid mechanics; their knowledge in these subjects has to be developed as the course proceeds. The scheme adopted in the present series is as follows. First, some basic training in mechanics, to a level about equivalent to the first seven chapters of the author's A First Course in Continuum Mechanics (Prentice-Hall,lnc. 1977), is assumed. We then present some essential parts of biomechanics from the point of view of bioengineering, physiology, and medical applications. In the meantime, mechanics is developed through a sequence of problems and examples. The main text reads like physiology, while the exercises are planned like a mechanics textbook. The instructor may fil1 a dual role: teaching an essential branch of life science, and gradually developing the student's knowledge in mechanics.

Download or read book 8th European Medical and Biological Engineering Conference written by Tomaz Jarm and published by Springer Nature. This book was released on 2020-11-29 with total page 1198 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book aims at informing on new trends, challenges and solutions, in the multidisciplinary field of biomedical engineering. It covers traditional biomedical engineering topics, as well as innovative applications such as artificial intelligence in health care, tissue engineering , neurotechnology and wearable devices. Further topics include mobile health and electroporation-based technologies, as well as new treatments in medicine. Gathering the proceedings of the 8th European Medical and Biological Engineering Conference (EMBEC 2020), held on November 29 - December 3, 2020, in Portorož, Slovenia, this book bridges fundamental and clinically-oriented research, emphasizing the role of education, translational research and commercialization of new ideas in biomedical engineering. It aims at inspiring and fostering communication and collaboration between engineers, physicists, biologists, physicians and other professionals dealing with cutting-edge themes in and advanced technologies serving the broad field of biomedical engineering.

Download or read book Non invasive Characterization of the Mechanical Properties of Arteries written by Yanik Tardy and published by . This book was released on 1992 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of the Static Mechanical Properties of Rabbit Arteries written by Ananda Mohan Thangavelu and published by . This book was released on 1977 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experiments to Determine the Mechanical Properties of Arteries written by Itay Manor and published by . This book was released on 2015 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biology of the Arterial Wall written by Bernard I. Levy and published by Springer Science & Business Media. This book was released on 2007-11-23 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biology of the Arterial Wall is intended as a general reference text concerned with the biology of the vascular cells and the blood vessel wall under physiological and pathological conditions. One of the major functions of the arteries is to maintain a continuous blood flow to the organs whatever the pressure conditions, thanks to the vasomotor tone of the smooth muscle cells. Great advances have been made over the last decade in the understanding of the endothelial cells as integrators and transducers of signals originating from the blood stream. The pluripotent control functions of the endothelial cells in the vessel wall are now well recognized. A review of endothelial functions and dysfunctions is presented. Cell biology and molecular genetic studies have now identified an array of molecules elaborated by endothelial cells and vascular smooth muscle cells and by the blood-borne elements which interact with artery cells, defending the artery against injury and modulating evolving abnormal processes. Molecules which induce or inhibit endothelial and/or smooth muscle cells are currently under great scrutiny. Angiogenesis, which plays a major role in tumor growth, but may also be beneficial as a healing process in muscle ischemia, is discussed. Apoptosis, or programmed cell death, has only recently been recognized as an essential process in blood vessel modeling and remodeling. An overview of apoptosis in the vascular system is presented. It is increasingly evident that the adjustments of the blood vessel wall are made in the presence of deforming disease processes such as hypertension and atherosclerosis. The second part of the book is concerned with the blood vessel wall in disease conditions. Several chapters review the role of the vessel and vascular cells in inflammation, and vascular remodeling during arterial hypertension and aging. One chapter is devoted to atherogenesis, atheroma and plaque instability, followed by the pathophysiology of post-angioplasty restenosis, which is a crucial issue in modern interventional cardiology.

Download or read book The Mechanical Properties of Arterial Walls and Their Replacements written by Cabe Michael Owens and published by . This book was released on 1985 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Deformation Rate on the Mechanical Properties of Arteries written by and published by . This book was released on 2007 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: