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Cardiovascular Engineering and Technology

David A Steinman, Francesco Migliavacca
No abstract text is available yet for this article.
November 12, 2018: Cardiovascular Engineering and Technology
Maureen B Gallagher, Kenneth I Aycock, Brent A Craven, Keefe B Manning
PURPOSE: Although many previous computational fluid dynamics (CFD) studies have investigated the hemodynamics in the inferior vena cava (IVC), few studies have compared computational predictions to experimental data, and only qualitative comparisons have been made. Herein, we provide particle image velocimetry (PIV) measurements of flow in a patient-averaged IVC geometry under idealized conditions typical of those used in the preclinical evaluation of IVC filters. METHODS: Measurements are acquired under rest and exercise flow rate conditions in an optically transparent model fabricated using 3D printing...
November 8, 2018: Cardiovascular Engineering and Technology
Anna Maria Tango, Jacob Salmonsmith, Andrea Ducci, Gaetano Burriesci
PURPOSE: The understanding of the optimum function of the healthy aortic valve is essential in interpreting the effect of pathologies in the region, and in devising effective treatments to restore the physiological functions. Still, there is no consensus on the operating mechanism that regulates the valve opening and closing dynamics. The aim of this study is to develop a numerical model that can support a better comprehension of the valve function and serve as a reference to identify the changes produced by specific pathologies and treatments...
November 7, 2018: Cardiovascular Engineering and Technology
Fredrik E Fossan, Jacob Sturdy, Lucas O Müller, Andreas Strand, Anders T Bråten, Arve Jørgensen, Rune Wiseth, Leif R Hellevik
PURPOSE: The main objectives of this study are to validate a reduced-order model for the estimation of the fractional flow reserve (FFR) index based on blood flow simulations that incorporate clinical imaging and patient-specific characteristics, and to assess the uncertainty of FFR predictions with respect to input data on a per patient basis. METHODS: We consider 13 patients with symptoms of stable coronary artery disease for which 24 invasive FFR measurements are available...
October 31, 2018: Cardiovascular Engineering and Technology
Alessandro Boccadifuoco, Alessandro Mariotti, Katia Capellini, Simona Celi, Maria Vittoria Salvetti
PURPOSE: Computational fluid dynamics (CFD) and 4D-flow magnetic resonance imaging (MRI) are synergically used for the simulation and the analysis of the flow in a patient-specific geometry of a healthy thoracic aorta. METHODS: CFD simulations are carried out through the open-source code SimVascular. The MRI data are used, first, to provide patient-specific boundary conditions. In particular, the experimentally acquired flow rate waveform is imposed at the inlet, while at the outlets the RCR parameters of the Windkessel model are tuned in order to match the experimentally measured fractions of flow rate exiting each domain outlet during an entire cardiac cycle...
October 24, 2018: Cardiovascular Engineering and Technology
Effat Soleimani, Manijhe Mokhtari-Dizaji, Nasser Fatouraee, Hazhir Saberi
PURPOSE: We developed a modified Kelvin model so that the periodic changes of the arterial intima-media thickness (IMT) over the cardiac cycle were involved. Modified model was implemented for carotid artery, solved via a parameter optimization technique and biomechanical parameters of the model. METHODS: Consecutive ultrasonic images of the common carotid artery of 30 male patients including 10 healthy subjects, 10 subjects with mild and 10 subjects with sever stenosis were recorded and processed offline...
October 24, 2018: Cardiovascular Engineering and Technology
Rossella Campobasso, Francesca Condemi, Magalie Viallon, Pierre Croisille, Salvatore Campisi, Stéphane Avril
PURPOSE: It has been reported clinically that rupture or dissections in thoracic aortic aneurysms (TAA) often occur due to hypertension which may be modelled with sudden increase of peripheral resistance, inducing acute changes of blood volumes in the aorta. There is clinical evidence that more compliant aneurysms are less prone to rupture as they can sustain such changes of volume. The aim of the current paper is to verify this paradigm by evaluating computationally the role played by the variation of peripheral resistance and the impact of aortic stiffness onto peak wall stress in ascending TAA...
October 19, 2018: Cardiovascular Engineering and Technology
Claire Conway
PURPOSE: The United States' Food and Drug Administration (FDA) recommends that device manufacturers demonstrate 10 years of equivalent life duration for endovascular stents. Yet since the early 2000s clinical evidence of stent strut fracture defies the recommendations for these FDA approved devices. Stent strut fracture has been correlated with a higher incidence of adverse clinical events, such as in-stent thrombosis and in-stent restenosis. METHODS: This paper reviews the current clinical evidence, computational modelling relating to fatigue lifetimes, experimental testing of coronary stents, and the related regulatory guidance and standards...
October 19, 2018: Cardiovascular Engineering and Technology
Hooman Yadollahi-Farsani, Marcus Herrmann, David Frakes, Brian Chong
PURPOSE: To gain insight into the influence of coils on aneurysmal hemodynamics, computational fluid dynamics (CFD) can be used. Conventional methods of modeling coils consider the explicit geometry of the deployed devices within the aneurysm and discretize the fluid domain. However, the complex geometry of a coil mass leads to cumbersome domain discretization along with a significant number of mesh elements. These problems have motivated a homogeneous porous medium coil model, whereby the explicit geometry of the coils is greatly simplified, and relevant homogeneous porous medium parameters are approximated...
October 18, 2018: Cardiovascular Engineering and Technology
Michele Conti, Stijn Vandenberghe, Stefania Marconi, Enrico Ferrari, Rodrigo M Romarowski, Simone Morganti, Ferdinando Auricchio, Stefanos Demertzis
INTRODUCTION: Endovascular treatments, such as transcatheter aortic valve implantation (TAVI), carry a risk of embolization due to debris dislodgement during various procedural steps. Although embolic filters are already available and marketed, mechanisms underlying cerebral embolism still need to be elucidated in order to further reduce cerebrovascular events. METHODS: We propose an experimental framework with an in silico duplicate allowing release of particles at the level of the aortic valve and their subsequent capture in the supra-aortic branches, simulating embolization under constant inflow and controlled hemodynamic conditions...
October 16, 2018: Cardiovascular Engineering and Technology
Brandon J Tefft, Joshua A Choe, Melissa D Young, Ryan S Hennessy, David W Morse, Jeffery A Bouchard, Herbert J Hedberg, Joseph F Consiglio, Dan Dragomir-Daescu, Robert D Simari, Amir Lerman
PURPOSE: Tissue engineered heart valves (TEHV) are being investigated to address the limitations of currently available valve prostheses. In order to advance a wide variety of TEHV approaches, the goal of this study was to develop a cardiac valve bioreactor system capable of conditioning living valves with a range of hydrodynamic conditions as well as capable of assessing hydrodynamic performance to ISO 5840 standards. METHODS: A bioreactor system was designed based on the Windkessel approach...
October 11, 2018: Cardiovascular Engineering and Technology
Ashish Tiwari, Satyendra Singh Chauhan
PURPOSE: Most of the previously studied non-Newtonian blood flow models considered blood viscosity to be constant but for correct measurement of flow rate and flow resistance, the hematocrit dependent viscosity will be better as various literature suggested the variable nature of blood viscosity. Present work concerns the steady and pulsatile nature of blood flow through constricted blood vessels. Two-fluid model for blood is considered with the suspension of all the RBCs (erythrocytes) in the core region as a non-Newtonian (Herschel-Bulkley) fluid and the plasma in the cell free region near wall as a Newtonian fluid...
October 9, 2018: Cardiovascular Engineering and Technology
Prasanna Hariharan, Kenneth I Aycock, Martin Buesen, Steven W Day, Bryan C Good, Luke H Herbertson, Ulrich Steinseifer, Keefe B Manning, Brent A Craven, Richard A Malinauskas
PURPOSE: A credible computational fluid dynamics (CFD) model can play a meaningful role in evaluating the safety and performance of medical devices. A key step towards establishing model credibility is to first validate CFD models with benchmark experimental datasets to minimize model-form errors before applying the credibility assessment process to more complex medical devices. However, validation studies to establish benchmark datasets can be cost prohibitive and difficult to perform...
October 5, 2018: Cardiovascular Engineering and Technology
Salma El Batti, Mariano E Casciaro, Jean-Marc Alsac, Christian Latremouille, Pierre Julia, Elie Mousseaux, Damian Craiem
OBJECTIVES: To analyze the volumetric evolution of abdominal aortic aneurysms after endovascular sealing (EVAS) with the Nellix™ device during follow-up. METHODS: Patients who underwent elective EVAS in our institution in 2014 and 2015 were retrospectively reviewed. Preoperative, postoperative and 1-year scans were processed. A custom software was conceived to assess semi-automated measurements of the aneurysm sac and the endograft sizes including volume, maximum diameter, sectional area and perimeter...
October 4, 2018: Cardiovascular Engineering and Technology
Jan Brüning, Florian Hellmeier, Pavlo Yevtushenko, Titus Kühne, Leonid Goubergrits
PURPOSE: Numerical assessment of the pressure drop across an aortic coarctation using CFD is a promising approach to replace invasive catheter-based measurements. The aim of this study was to investigate and quantify the uncertainty of numerical calculation of the pressure drop introduced during two essential steps of medical image processing: segmentation of the patient-specific geometry and measurement of patient-specific flow rates from 4D-flow-MRI. METHODS: Based on the baseline segmentation, geometries with different stenosis diameters were generated for a sample of ten patients...
October 3, 2018: Cardiovascular Engineering and Technology
Timothy Ruesink, Rafael Medero, David Rutkowski, Alejandro Roldán-Alzate
PURPOSE: Arterial stiffness has predictive value for cardiovascular disease (CVD). Local artery stiffness can provide insight on CVD pathology and may be useful for diagnosis and prognosis. However, current methods are invasive, require real-time expertise for measurement, or are limited by arterial region. 4D Flow MRI can non-invasively measure local stiffness by estimating local pulse wave velocity (PWV). This technique can be applied to vascular regions, previously accessible only by invasive stiffness measurement methods...
September 14, 2018: Cardiovascular Engineering and Technology
Kristian Valen-Sendstad, Aslak W Bergersen, Yuji Shimogonya, Leonid Goubergrits, Jan Bruening, Jordi Pallares, Salvatore Cito, Senol Piskin, Kerem Pekkan, Arjan J Geers, Ignacio Larrabide, Saikiran Rapaka, Viorel Mihalef, Wenyu Fu, Aike Qiao, Kartik Jain, Sabine Roller, Kent-Andre Mardal, Ramji Kamakoti, Thomas Spirka, Neil Ashton, Alistair Revell, Nicolas Aristokleous, J Graeme Houston, Masanori Tsuji, Fujimaro Ishida, Prahlad G Menon, Leonard D Browne, Stephen Broderick, Masaaki Shojima, Satoshi Koizumi, Michael Barbour, Alberto Aliseda, Hernán G Morales, Thierry Lefèvre, Simona Hodis, Yahia M Al-Smadi, Justin S Tran, Alison L Marsden, Sreeja Vaippummadhom, G Albert Einstein, Alistair G Brown, Kristian Debus, Kuniyasu Niizuma, Sherif Rashad, Shin-Ichiro Sugiyama, M Owais Khan, Adam R Updegrove, Shawn C Shadden, Bart M W Cornelissen, Charles B L M Majoie, Philipp Berg, Sylvia Saalfield, Kenichi Kono, David A Steinman
PURPOSE: Image-based computational fluid dynamics (CFD) is widely used to predict intracranial aneurysm wall shear stress (WSS), particularly with the goal of improving rupture risk assessment. Nevertheless, concern has been expressed over the variability of predicted WSS and inconsistent associations with rupture. Previous challenges, and studies from individual groups, have focused on individual aspects of the image-based CFD pipeline. The aim of this Challenge was to quantify the total variability of the whole pipeline...
September 10, 2018: Cardiovascular Engineering and Technology
Philipp Berg, Samuel Voß, Sylvia Saalfeld, Gábor Janiga, Aslak W Bergersen, Kristian Valen-Sendstad, Jan Bruening, Leonid Goubergrits, Andreas Spuler, Nicole M Cancelliere, David A Steinman, Vitor M Pereira, Tin Lok Chiu, Anderson Chun On Tsang, Bong Jae Chung, Juan R Cebral, Salvatore Cito, Jordi Pallarès, Gabriele Copelli, Benjamin Csippa, György Paál, Soichiro Fujimura, Hiroyuki Takao, Simona Hodis, Georg Hille, Christof Karmonik, Saba Elias, Kerstin Kellermann, Muhammad Owais Khan, Alison L Marsden, Hernán G Morales, Senol Piskin, Ender A Finol, Mariya Pravdivtseva, Hamidreza Rajabzadeh-Oghaz, Nikhil Paliwal, Hui Meng, Santhosh Seshadhri, Matthew Howard, Masaaki Shojima, Shin-Ichiro Sugiyama, Kuniyasu Niizuma, Sergey Sindeev, Sergey Frolov, Thomas Wagner, Alexander Brawanski, Yi Qian, Yu-An Wu, Kent D Carlson, Dan Dragomir-Daescu, Oliver Beuing
PURPOSE: Advanced morphology analysis and image-based hemodynamic simulations are increasingly used to assess the rupture risk of intracranial aneurysms (IAs). However, the accuracy of those results strongly depends on the quality of the vessel wall segmentation. METHODS: To evaluate state-of-the-art segmentation approaches, the Multiple Aneurysms AnaTomy CHallenge (MATCH) was announced. Participants carried out segmentation in three anonymized 3D DSA datasets (left and right anterior, posterior circulation) of a patient harboring five IAs...
September 6, 2018: Cardiovascular Engineering and Technology
Scott A Metzler, Steven C Waller, James N Warnock
Current protocols for mechanical preconditioning of tissue engineered heart valves have focused on application of pressure, flexure and fluid flow to stimulate collagen production, ECM remodeling and improving mechanical performance. The aim of this study was to determine if mechanical preconditioning with cyclic stretch could promote an intact endothelium that resembled the viability and morphology of a native valve. Confocal laser scanning microscopy was used to image endothelial cells on aortic valve strips subjected to static incubation or physiological strain regimens...
August 23, 2018: Cardiovascular Engineering and Technology
Anna Nikishova, Lourens Veen, Pavel Zun, Alfons G Hoekstra
Coronary artery stenosis, or abnormal narrowing, is a widespread and potentially fatal cardiac disease. After treatment by balloon angioplasty and stenting, restenosis may occur inside the stent due to excessive neointima formation. Simulations of in-stent restenosis can provide new insight into this process. However, uncertainties due to variability in patient-specific parameters must be taken into account. We performed an uncertainty quantification (UQ) study on a complex two-dimensional in-stent restenosis model...
August 22, 2018: Cardiovascular Engineering and Technology
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