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https://www.readbyqxmd.com/read/29735263/an-anisotropic-constitutive-model-for-immersogeometric-fluid-structure-interaction-analysis-of-bioprosthetic-heart-valves
#1
Michael C H Wu, Rana Zakerzadeh, David Kamensky, Josef Kiendl, Michael S Sacks, Ming-Chen Hsu
This paper considers an anisotropic hyperelastic soft tissue model, originally proposed for native valve tissue and referred to herein as the Lee-Sacks model, in an isogeometric thin shell analysis framework that can be readily combined with immersogeometric fluid-structure interaction (FSI) analysis for high-fidelity simulations of bioprosthetic heart valves (BHVs) interacting with blood flow. We find that the Lee-Sacks model is well-suited to reproduce the anisotropic stress-strain behavior of the cross-linked bovine pericardial tissues that are commonly used in BHVs...
April 12, 2018: Journal of Biomechanics
https://www.readbyqxmd.com/read/29730841/grading-of-aortic-stenosis-severity-a-head-to-head-comparison-between-cardiac-magnetic-resonance-imaging-and-echocardiography
#2
Cesare Mantini, Gabriele Di Giammarco, Jacopo Pizzicannella, Sabina Gallina, Fabrizio Ricci, Emilia D'Ugo, Marziale Marchetti, Antonio Raffaele Cotroneo, Nauman Ahmed, Chiara Bucciarelli-Ducci, Armando Tartaro, Raffaele De Caterina
AIM: To prospectively evaluate the accuracy of cardiac magnetic resonance (cMR) imaging for the assessment of aortic valve effective orifice area (EOA) by continuity equation and anatomical aortic valve area (AVA) by direct planimetry, as compared with transthoracic (TTE) and transesophageal (TEE) two-dimensional (2D) echocardiography, respectively. METHODS AND RESULTS: A total of 31 patients (21 men, 10 women, mean age 69 ± 10 years) with moderate-to-severe aortic stenosis (AS) diagnosed by TTE and scheduled for elective aortic valve replacement, underwent both cMR and TEE...
May 5, 2018: La Radiologia Medica
https://www.readbyqxmd.com/read/29717983/whole-heart-4d-flow-cardiac-magnetic-resonance-in-healthy-dogs
#3
N Pfammatter, I Campagna, M Baron Toaldo, E Bruellmann, H Richter, P Kircher, M Dennler
In cardiac magnetic resonance imaging (CMR), accurate flow measurements rely on perpendicular plane-alignment with flow direction. For 2D phase contrast (PC) cardiac magnetic resonance measurements, planes have to be defined during the examination of the heart, which is time consuming and error-prone. Collection of flow information of the entire volume of the heart by a 4D flow CMR postpones plane alignment to post-processing. Sampling of such a large amount of data requires acceleration of data acquisition with techniques such as SENSitivity Encoding (k-t SENSE) or Broad-use Linear Acquisition Speed-up Technique (k-t BLAST)...
May 2018: Schweizer Archiv Für Tierheilkunde
https://www.readbyqxmd.com/read/29715592/fucoidan-vegf-based-surface-modification-of-decellularized-pulmonary-heart-valve-improves-the-antithrombotic-and-re-endothelialization-potential-of-bioprostheses
#4
N Marinval, M Morenc, M N Labour, A Samotus, A Mzyk, V Ollivier, M Maire, K Jesse, K Bassand, A Niemiec-Cyganek, O Haddad, M P Jacob, F Chaubet, N Charnaux, P Wilczek, H Hlawaty
Decellularized porcine heart valves offer promising potential as biocompatible prostheses. However, this procedure alter matrix fibres and glycans, leading to lower biomechanical resistance and increased their thrombotic potential. Therefore, their durability is limited due to calcification and weak regeneration in vivo. Surface modifications are highly requested to improve the scaffolds re-endothelialization required to restore functional and haemocompatible heart valve. Fucoidan, a natural sulphated polysaccharide, carries antithrombotic and anti-inflammatory properties and is known to enhance endothelial adhesion and proliferation when associated with vascular endothelial growth factor (VEGF)...
March 16, 2018: Biomaterials
https://www.readbyqxmd.com/read/29713288/3d-fluid-structure-interaction-simulation-of-aortic-valves-using-a-unified-continuum-ale-fem-model
#5
Jeannette H Spühler, Johan Jansson, Niclas Jansson, Johan Hoffman
Due to advances in medical imaging, computational fluid dynamics algorithms and high performance computing, computer simulation is developing into an important tool for understanding the relationship between cardiovascular diseases and intraventricular blood flow. The field of cardiac flow simulation is challenging and highly interdisciplinary. We apply a computational framework for automated solutions of partial differential equations using Finite Element Methods where any mathematical description directly can be translated to code...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29712750/x-ray-computed-tomography-study-of-the-flight-adapted-tracheal-system-in-the-blowfly-calliphora-vicina-analysing-the-ventilation-mechanism-and-flow-directing-valves
#6
Lutz Thilo Wasserthal, Peter Cloetens, Rainer H Fink, Lennard Knut Wasserthal
After the discovery of the flight-motor driven unidirectional gas exchange with rising PO2 in the blowfly, X-ray computer tomography (CT) was used to visualize the organization of the tracheal system in the anterior body with emphasis on the arrangement of the pathways for the airflows. The fly's head is preferentially supplied by cephalic tracheae originating from the ventral orifice of the mesothoracic spiracle (Sp1). The respiratory airflow during flight is a by-product of cyclic deformations of the thoracic box by the flight muscles...
April 30, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/29697598/a-phase-1-study-of-a-novel-bidirectional-perfusion-cannula-in-patients-undergoing-femoral-cannulation-for-cardiac-surgery
#7
Silvana F Marasco, Elli Tutungi, Shirley A Vallance, Andrew A Udy, Justin C Negri, Adam D Zimmet, David C McGiffin, Vincent A Pellegrino, Randall A Moshinsky
OBJECTIVE: Leg ischemia is a serious complication of femoral artery cannulation. The primary aim of this study was to assess the safety and efficacy of a novel bidirectional femoral arterial cannula (Sorin Group USA, a wholly owned subsidiary of LivaNova PLC, Arvada, CO USA) that provides both antegrade and retrograde flow, in patients undergoing peripheral cannulation for cardiopulmonary bypass during cardiac surgery. METHODS: Patients undergoing routine cardiac surgery requiring femoral artery cannulation for cardiopulmonary bypass were identified preoperatively...
April 24, 2018: Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery
https://www.readbyqxmd.com/read/29695249/aortic-flow-patterns-and-wall-shear-stress-maps-by-4d-flow-cardiovascular-magnetic-resonance-in-the-assessment-of-aortic-dilatation-in-bicuspid-aortic-valve-disease
#8
José Fernando Rodríguez-Palomares, Lydia Dux-Santoy, Andrea Guala, Raquel Kale, Giuliana Maldonado, Gisela Teixidó-Turà, Laura Galian, Marina Huguet, Filipa Valente, Laura Gutiérrez, Teresa González-Alujas, Kevin M Johnson, Oliver Wieben, David García-Dorado, Arturo Evangelista
BACKGROUND: In patients with bicuspid valve (BAV), ascending aorta (AAo) dilatation may be caused by altered flow patterns and wall shear stress (WSS). These differences may explain different aortic dilatation morphotypes. Using 4D-flow cardiovascular magnetic resonance (CMR), we aimed to analyze differences in flow patterns and regional axial and circumferential WSS maps between BAV phenotypes and their correlation with ascending aorta dilatation morphotype. METHODS: One hundred and one BAV patients (aortic diameter ≤ 45 mm, no severe valvular disease) and 20 healthy subjects were studied by 4D-flow CMR...
April 26, 2018: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/29682435/assessment-of-ventriculoperitoneal-shunt-function-using-ultrasound-characterization-of-valve-interface-oscillation-as-a-proxy
#9
April Aralar, Matthew Bird, Robert Graham, Beomseo Koo, Parag Chitnis, Siddhartha Sikdar, Mahesh Shenai
Objective Ventricular shunts are a mainstay of hydrocephalus treatment, but the detection of its clinical failure often relies on circumstantial evidence. A direct, non-interventional method for reliably evaluating cerebrospinal fluid (CSF) function does not exist due to the difficulty of measuring in vivo flow characteristics. The objective of this study is to apply a novel method of ultrasound monitoring to characterize the oscillation observed during pulsatile CSF flow and failure states in an in vitro and cadaveric model...
February 19, 2018: Curēus
https://www.readbyqxmd.com/read/29667250/a-new-2d-echocardiographic-approach-to-evaluate-the-membrane-and-valve-movement-of-the-berlin-heart-excor-vad-chamber-in-pediatric-vad-patients
#10
Arianna Di Molfetta, Roberta Iacobelli, Gianfranco Ferrari, Sergio Filippelli, Gianluigi Perri, Alessandra Toscano, Rachele Adorisio, Paolo Guccione, Antonio Amodeo
The use of Berlin Heart EXCOR VAD (BH) is a validated therapy to bridge pediatric patients to heart transplant. Serial echocardiographic (ECHO) assessment of VAD patients is necessary to support patients' management. This work aims at developing an innovative strategy to evaluate the BH device functioning by ECHO and its interaction with the native heart in a pediatric population. ECHO evaluation of BH membrane movement, and inflow and outflow valves was performed in 2D, 2D-color Doppler, M-mode, and M-mode color Doppler to assess the functioning of the device by direct positioning of the ECHO probe on the BH cannulas and membranes...
April 2018: Artificial Organs
https://www.readbyqxmd.com/read/29569259/varicocele-is-the-root-cause-of-bph-destruction-of-the-valves-in-the-spermatic-veins-produces-elevated-pressure-which-diverts-undiluted-testosterone-directly-from-the-testes-to-the-prostate
#11
M Goren, Y Gat
In varicocele, there is venous flow of free testosterone (FT) directly from the testes into the prostate. Intraprostatic FT accelerates prostate cell production and prolongs cell lifespan, leading to the development of BPH. We show that in a large group of patients presenting with BPH, bilateral varicocele is found in all patients. A total of 901 patients being treated for BPH were evaluated for varicocele. Three diagnostic methods were used as follows: physical examination, colour flow Doppler ultrasound and contact liquid crystal thermography...
March 22, 2018: Andrologia
https://www.readbyqxmd.com/read/29544951/grading-of-mitral-regurgitation-in-mitral-valve-prolapse-using-the-average-pixel-intensity-method
#12
Victor Kamoen, Milad El Haddad, Marc De Buyzere, Tine De Backer, Frank Timmermans
AIMS: We recently reported the feasibility of the average pixel intensity (API) method for grading mitral regurgitation (MR) in a heterogeneous MR population. Since mitral valve prolapse (MVP) is an important cause of primary MR, we more specifically investigated the feasibility of the API method and the MR flow dynamics in patients with MVP. METHODS: Transthoracic echocardiography was performed by a single operator in consecutive MVP patients (n=112). MR was assessed using the API method, color Doppler, vena contracta width (VCW), effective regurgitant orifice area (PISA-EROA) and regurgitant volume (PISA-RV)...
May 1, 2018: International Journal of Cardiology
https://www.readbyqxmd.com/read/29505888/puncturing-of-lyophilized-tissue-engineered-vascular-matrices-enhances-the-efficiency-of-their-recellularization
#13
Agnieszka A Książek, Laura Frese, Petra E Dijkman, Bart Sanders, Sarah E Motta, Benedikt Weber, Simon P Hoerstrup
Data on in vitro engineered "off the shelf" matrices support the concept of endogenous cellular repopulation driving the graft's remodeling via immune-mediated response. This seems important to further accelerate the cell reconstitution and may play a crucial role when mononuclear cells are used. Nevertheless, studies on decellularized xenogeneic grafts showed only limited host cell repopulation post-implantation. This study aims at a systematic comparison of reseeding methods (dripping, injection, bathing in a cell suspension and combined puncturing-dripping method) to define the most efficient technique enhancing recellularization of tissue engineered vascular matrices (patches, vessels, small diameter and standard size valves) prior implantation...
April 15, 2018: Acta Biomaterialia
https://www.readbyqxmd.com/read/29493213/nanoclay-based-self-supporting-responsive-nanocomposite-hydrogels-for-printing-applications
#14
Yifei Jin, Yangyang Shen, Jun Yin, Jin Qian, Yong Huang
Stimuli-responsive hydrogels and/or composite hydrogels have been of great interest for various printing applications including four-dimensional printing. Although various responsive hydrogels and/or composite hydrogels have been found to respond to given stimuli and change shapes as designed, the fabrication of three-dimensional (3D) structures from such responsive hydrogels is still a challenge due to their poor 3D printability, and most of the responsive material-based patterns are two-dimensional (2D) in nature...
March 28, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29488031/effects-of-mitral-chordae-tendineae-on-the-flow-in-the-left-heart-ventricle
#15
Valentina Meschini, Marco D de Tullio, Roberto Verzicco
In this paper a computational model for the ventricular flow with a mitral valve and modeled chordae tendineae is presented. The results are compared with an analogous case in which the chordae are not included and their presence is replaced by kinematic boundary conditions. The problem is studied using direct numerical simulation of the Navier-Stokes equations, two-way coupled with a structural solver for the ventricle and mitral valve dynamics. An experimental validation of the model is performed by a comparison of the results with a companion dedicated experiment...
February 28, 2018: European Physical Journal. E, Soft Matter
https://www.readbyqxmd.com/read/29469203/coupling-imaged-capillary-isoelectric-focusing-with-mass-spectrometry-using-a-nanoliter-valve
#16
Cristina Montealegre, Christian Neusüß
Imaged capillary isoelectric focusing (iCIEF) is a powerful separation technique applied frequently for the analysis of biotherapeutics. However, direct mass spectrometric characterization is usually not possible. Here, focused peaks from an iCIEF system are transferred to a four-port nanoliter valve where peaks of interest are cut and transferred directly (flow injection) or via capillary zone electrophoresis to electrospray mass spectrometry. At first, flow injection coupling was tested with a mixture of peptides showing intraday precision (RSD) of 20...
February 22, 2018: Electrophoresis
https://www.readbyqxmd.com/read/29454583/post-operative-ventricular-flow-dynamics-following-atrioventricular-valve-surgical-and-device-therapies-a-review
#17
REVIEW
Yen Ngoc Nguyen, Munirah Ismail, Foad Kabinejadian, Edgar Lik Wui Tay, Hwa Liang Leo
Intra-ventricular flow dynamics has recently emerged as an important evaluation and diagnosis tool in different cardiovascular conditions. The formation of vortex pattern during the cardiac cycle has been suggested to play important epigenetic and energy-modulation roles in cardiac remodelling, adaptations and mal-adaptations. In this new perspective, flow alterations due to different cardiovascular procedures can affect the long-term outcome of those procedures. Especially, repairs and replacements performed on atrioventricular valves are likely to exert direct impact on intra-ventricular flow pattern...
April 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29451963/aortic-valve-stenosis-and-aortic-diameters-determine-the-extent-of-increased-wall-shear-stress-in-bicuspid-aortic-valve-disease
#18
Emile S Farag, Pim van Ooij, R Nils Planken, Kayleigh C P Dukker, Frederiek de Heer, Berto J Bouma, Danielle Robbers-Visser, Maarten Groenink, Aart J Nederveen, Bas A J M de Mol, Jolanda Kluin, S Matthijs Boekholdt
BACKGROUND: Use of 4-dimensional flow magnetic resonance imaging (4D-flow MRI) derived wall shear stress (WSS) heat maps enables identification of regions in the ascending aorta with increased WSS. These regions are subject to dysregulation of the extracellular matrix and elastic fiber degeneration, which is associated with aortic dilatation and dissection. PURPOSE: To evaluate the effect of the presence of aortic valve stenosis and the aortic diameter on the peak WSS and surface area of increased WSS in the ascending aorta...
February 16, 2018: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29446506/picomolar-scale-compound-specific-isotope-analyses
#19
Allison A Baczynski, Pratigya J Polissar, Dieter Juchelka, Johannes Schwieters, Andreas Hilkert, Roger E Summons, Katherine H Freeman
RATIONALE: We report modifications to compound-specific isotope analyses (CSIA) to enable high-precision isotopic analyses of picomoles of carbon for intact organic molecules. This sample size is two orders of magnitude below the amounts required for commercial systems. The greatly enhanced sensitivity of this system expands molecular isotope studies and applications previously prohibited by low concentrations and small samples. METHODS: We utilize the resolving power and low volumetric flow rates of narrow-bore capillary gas chromatography to improve sample transfer efficiency while maintaining narrow peak widths...
May 15, 2018: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/29417607/fetal-pulmonary-valve-stenosis-or-atresia-with-intact-ventricular-septum-predictors-of-need-for-neonatal-intervention
#20
Qing Wang, Yu Rong Wu, Xian Ting Jiao, Peng Fei Wu, Li Qing Zhao, Sun Chen, Kun Sun
OBJECTIVES: To compare the fetal echocardiographic measurements and neonatal outcome of fetuses with diagnosis of critical pulmonary stenosis (CPS/IVS) and pulmonary atresia with intact ventricular septum (PA/IVS) to identify the predictors of neonatal ductus dependence and the need for neonatal intervention. METHODS: Forty-four fetuses with a diagnosis of membranous PA/IVS or CPS/IVS referred to Shanghai Xinhua Hospital Affiliated to Shanghai Jiaotong University between June 2009 and November 2014 were respectively analyzed...
March 2018: Prenatal Diagnosis
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