Characterization of the Mechanical Properties of the Human Aortic Arch Using an Expansion Method

Analyzing cardiovascular diseases leads to multidisciplinary problems which require transversal and complementary approaches. This study focuses on the identification of the mechanical properties of the aortic arch. Stereo-correlation technique is used to measure the strain field in the aortic arch during its expansion. The aorta is immersed in water which allows better results in terms of measurement method and to take into account the residual stress and strain effects. Results are obtained at different values of expansion: 9 samples are collected, 7 of them are frozen before the experiment and 2 are fresh. The mean age is 76 years old at the volunteers? time of death. 4 samples did not lead to conclusive results because of the quality of the arterial wall and leaks that happened during the experiment preventing a proper expansion. The horizontal and vertical displacements are relatively homogeneous for all the samples: two preferred radial and longitudinal directions are observed. The strain fields associated with these directions show heterogeneities and have significant differences between fresh and frozen specimen. The final objective is to perform virtual surgical simulation of the whole endovascular stent graft procedure for an aortic aneurysm. This procedure has a high rate of short-term success and its indication compared to open surgery is increasing but it needs to be more reliable and secure. In this context, it is important to identify the mechanical properties of the aorta for further numerical simulations

COMPUTER AIDED SURGERY: APPLICATION TO AORTIC DISSECTION

International audienceCardiovascular diseases are the leading cause of mortality in the industrialized world. Among these diseases, aortic dissection is relatively unknown and difficult to treat, with a survival rate for most severe cases not exceeding 10%. This pathology occurs when an injury leads to a localized tear of the innermost layer of the aorta

Essential oils and distilled straws of lavender and lavandin: a review of current use and potential application in white biotechnology

The Lavandula genus, which includes lavender (Lavandula angustifolia) and lavandin (L. angustifolia x Lavandula latifolia), is cultivated worldwide for its essential oils, which find applications in perfumes, cosmetics, food processing and, more recently, in aromatherapy products. The chemical composition of lavender and lavandin essential oils, usually produced by steam distillation from the flowering stems, is characterized by the presence of terpenes (e.g. linalool and linalyl acetate) and terpenoids (e.g. 1,8-cineole), which are mainly responsible for their characteristic flavour and their biological and therapeutic properties. Lavender and lavandin distilled straws, the by-products of oil extraction, were traditionally used for soil replenishment or converted to a fuel source. They are mineral- and carbon-rich plant residues and, therefore, a cheap, readily available source of valuable substances of industrial interest, especially aroma and antioxidants (e.g. terpenoids, lactones and phenolic compounds including coumarin, herniarin, alpha-bisabolol, rosmarinic and chlorogenic acids). Accordingly, recent studies have emphasized the possible uses of lavender and lavandin straws in fermentative or enzymatic processes involving various microorganisms, especially filamentous fungi, for the production of antimicrobials, antioxidants and other bioproducts with pharmaceutical and cosmetic activities, opening up new challenging perspectives in white biotechnology applications

Computer Aided Surgery: Application to Aortic Dissection

International audienceIn cardiovascular disease, aortic dissection is relatively unknown and difficult to treat. Endovascular treatment seeks to obliterate the entrances to the false lumen with a stent. The currently available surgical tools for endovascular procedures are selected only from information based on medical imaging techniques. The images are carried out before the intervention and therefore do not consider the deformation of the vascular structure by the implementation of the prosthesis. While many biomechanical studies have been done on the endovascular treatment of aneurysms of the abdominal aorta, there are, however, very few such studies on aortic dissections. This paper aims to present a numerical tool, from the open-source software FOAM-Extend®, allowing for Multiphysics numerical simulations performing the fluid-structure coupling between the hemodynamics and the arterial deformation to assist in the planning process. And, in addition using Abaqus software we realize the placement of the surgical tools in a 'biomecano-faithful' model

Patient-specific CFD simulations using MPTT rheological model with 4D cardiovascular MRI validation

23rd Congress of the European Society of Biomechanics, SEVILLE, ESPAGNE, 02-/07/2017 - 05/07/2017Cardiovascular diseases are the leading cause of death worldwide. Their analysis leads to multidisciplinary problems that require diversity, transversal and complementary approaches. This contribution is part of a research project in Computer Aided Surgery and intends to contribute to the improvement of TEVAR procedures in terms of accuracy and optimization of the operating strategy. It aims to virtually simulate the whole endovascular stent graft procedure for an aortic aneurysm. An image correlation technique was used during an expansion test and a uniaxial tensile test to calculate strains on the aortic arch. Simulations of blood flow in the thoracic aorta were then performed in a healthy patient using a Modified Phan-Thien and Tanner rheological model. A fluid-structure coupling validates the results by approaching the dynamic imaging conditions

Comportement mécanique de la crosse aortique et simulations numériques de l'écoulement sanguin validées par IRM 4D

3e Journées scientifiques Franco-Maghrébines : Caractérisation des Matériaux Complexes, PARIS, FRANCE, 28-/11/2016 - 30/11/2016Ce travail fait partie d'un projet de recherche en chirurgie virtuelle avec pour objectif la proposition d'une solu-tion de localisation et de contrôle peropératoire précis du largage d'une endoprothèse dans un anévrisme de l'aorte thoracique.Une technique de corrélation d'images a été utilisée pendant un test en gonflementet un test de traction uni-axialeafin d'observer les déformations sur une aorte thoracique. Une loi polynomiale de comportement hyperélastiqueincompressible isotrope a été utilisée pour caractériser mécaniquement le matériau. Des simulations d'écoulement sanguin dans l'aorte thoracique ont ensuite été réa-lisées chez un patient sain avec le logiciel OpenFOAM. Le modèle rhéologique non-Newtonien de Phan-Thien et Tanner modifié (MPTT) a été implanté dans OpenFOAM et les résultats obtenusà partir de ce modèle comparésau modèle Newtonien ainsi qu'aux données de l'IRM 4D pendant un cycle cardiaque.Le modèle rhéo-logiqueMPTT montre plus de similarités avec les données IRM pendant les phases systolique et diastolique que le modèle Newto-nienou Newtoniengénéralisé. Les résultats expérimentaux sur la crosse aortique ont permis d'obtenir des coefficients pour la loi de comportement de la structure. Un couplage fluide-structure réalisé entre OpenFOAM et Abaqus© permettrade valider plus précisé-ment les résultatsen se rapprochant des conditions d'obtention de l'imagerie dynamiqu

Characterization of the aortic arch behaviour and CFD simulations validaded with 4D Cardiovascular MRI

22d congress of the European Society of Biomechanics, LYON, FRANCE, 10-/07/2016 - 13/07/2016Cardiovascular diseases are the leading cause of death worldwide. Their analysis leads to multidisciplinary problems that require diversity, transversal and complementary approaches. This contribution is part of a research project in Computer Aided Surgeryand intends to contribute to the improvement of TEVAR procedures in terms of accuracy and optimization of the operating strategy. The aim is first to identify the aortic arch mechanical behaviourusinga stereo-correlation technique. AFluid-Structure Interaction computation will be then made including non-Newtonian blood behaviour validated with4DCardiovascular Magnetic Resonance Imaging. This wouldprovide a diagnostic tool and support for clinical planning

Comparison between a generalized Newtonian model and a network-type multiscale model for hemodynamic behavior in the aortic arch: Validation with 4D MRI data for a case study

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In vitro assessment of abdominal aortic dissection hemodynamics based on particle image velocimetry

International audienceAortic Dissection (AD) is a condition in which the inner layer of the vessel tears causing separation between the inner and middle layers of the aorta. Blood surges into the tears, resulting in vulnerable secondary blood flow channel. Surgery consists in positioning a stent graft in the damaged area to reinforce vessel walls and redirect flow [1]. Tears, surgical tools insertion and stent graft positioning generate flow field disturbances that may influence the evolution of the disease. Many studies have investigated flow disturbances in Abdominal Aorta (AA) under healthy, dissection and post-surgical conditions with the use of AA phantom [2-4]. However, non-Newtonian behaviour is rarely investigated in such aorta phantom. The current study focuses on replicating AA non-Newtonian flow patterns in pathological and stented AA compliant phantoms.La dissection aortique est une pathologie initiée par une déchirure de la couche interne du vaisseau causant une séparation entre les couches composant la paroi de l’aorte. La pénétration du sang dans la déchirure engendre la formation d’un chenal secondaire et fragilise la paroi. Une technique de chirurgie consiste à déployer une endoprothèse au niveau de la zone endommagée afin de renforcer la paroi et de rediriger l’écoulement sanguin [1]. La déchirure, l’insertion d’outils chirurgicaux et le positionnement de l’endoprothèse sont des sources de perturbations de l’écoulement qui peuvent influencer l’évolution de la maladie. De nombreuse études ont investigué la perturbation des écoulements dans l’aorte saine, disséquée et post-chirurgie sur des fantômes vaisseaux sanguins. Néanmoins, la problématique non-newtonienne de l’écoulement est rarement traitée dans de tels modèles. Cette étude porte sur la reproduction d’écoulements non-newtoniens dans un fantôme d’aorte pathologique pré et post déploiement d’endoprothèse