Publications by authors named "Mariano Vázquez"

16 Publications

  • Page 1 of 1

Concomitant Respiratory Failure Can Impair Myocardial Oxygenation in Patients with Acute Cardiogenic Shock Supported by VA-ECMO.

J Cardiovasc Transl Res 2021 Feb 23. Epub 2021 Feb 23.

Department of Surgery, Visible Heart® Laboratories, University of Minnesota Medical School, B172 Mayo, MMC 195, 420 Delaware Street SE, Minneapolis, MN, 55455, USA.

Venous-arterial extracorporeal membrane oxygenation (VA-ECMO) treatment for acute cardiogenic shock in patients who also have acute lung injury predisposes development of a serious complication called "north-south syndrome" (NSS) which causes cerebral hypoxia. NSS is poorly characterized and hemodynamic studies have focused on cerebral perfusion ignoring the heart. We hypothesized in NSS the heart would be more likely to receive hypoxemic blood than the brain due to the proximity of the coronary arteries to the aortic annulus. To test this, we conducted a computational fluid dynamics simulation of blood flow in a human supported by VA-ECMO. Simulations quantified the fraction of blood at each aortic branching vessel originating from residual native cardiac output versus VA-ECMO. As residual cardiac function was increased, simulations demonstrated myocardial hypoxia would develop prior to cerebral hypoxia. These results illustrate the conditions where NSS will develop and the relative cardiac function that will lead to organ-specific hypoxia. Illustration of the impact of north-south syndrome on organ-specific oxygen delivery. Patients on VA-ECMO have two sources of blood flow, one from the VA-ECMO circuit and one from the residual cardiac function. When there is no residual cardiac function, all organs are perfused with oxygenated blood. As myocardial recovery progresses, blood supply from the two sources will begin to mix resulting in non-homogeneous mixing and differential oxygenation based upon the anatomical site of branching vessels.
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http://dx.doi.org/10.1007/s12265-021-10110-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7901681PMC
February 2021

Remoras pick where they stick on blue whales.

J Exp Biol 2020 Oct 28;223(Pt 20). Epub 2020 Oct 28.

Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA 93950, USA.

Animal-borne video recordings from blue whales in the open ocean show that remoras preferentially adhere to specific regions on the surface of the whale. Using empirical and computational fluid dynamics analyses, we show that remora attachment was specific to regions of separating flow and wakes caused by surface features on the whale. Adhesion at these locations offers remoras drag reduction of up to 71-84% compared with the freestream. Remoras were observed to move freely along the surface of the whale using skimming and sliding behaviors. Skimming provided drag reduction as high as 50-72% at some locations for some remora sizes, but little to none was available in regions where few to no remoras were observed. Experimental work suggests that the Venturi effect may help remoras stay near the whale while skimming. Understanding the flow environment around a swimming blue whale will inform the placement of biosensor tags to increase attachment time for extended ecological monitoring.
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http://dx.doi.org/10.1242/jeb.226654DOI Listing
October 2020

Cardiac computational modelling.

Rev Esp Cardiol (Engl Ed) 2021 Jan 15;74(1):65-71. Epub 2020 Aug 15.

Barcelona Supercomputing Center & ELEM Biotech, Barcelona, Spain.

Cardiovascular diseases currently have a major social and economic impact, constituting one of the leading causes of mortality and morbidity. Personalized computational models of the heart are demonstrating their usefulness both to help understand the mechanisms underlying cardiac disease, and to optimize their treatment and predict the patient's response. Within this framework, the Spanish Research Network for Cardiac Computational Modelling (VHeart-SN) has been launched. The general objective of the VHeart-SN network is the development of an integrated, modular and multiscale multiphysical computational model of the heart. This general objective is addressed through the following specific objectives: a) to integrate the different numerical methods and models taking into account the specificity of patients; b) to assist in advancing knowledge of the mechanisms associated with cardiac and vascular diseases; and c) to support the application of different personalized therapies. This article presents the current state of cardiac computational modelling and different scientific works conducted by the members of the network to gain greater understanding of the characteristics and usefulness of these models.
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http://dx.doi.org/10.1016/j.rec.2020.05.024DOI Listing
January 2021

In-silico human electro-mechanical ventricular modelling and simulation for drug-induced pro-arrhythmia and inotropic risk assessment.

Prog Biophys Mol Biol 2021 Jan 22;159:58-74. Epub 2020 Jul 22.

Department of Computer Science, University of Oxford, Parks Road OX1 3QD, Oxford, United Kingdom. Electronic address:

Human-based computational modelling and simulation are powerful tools to accelerate the mechanistic understanding of cardiac patho-physiology, and to develop and evaluate therapeutic interventions. The aim of this study is to calibrate and evaluate human ventricular electro-mechanical models for investigations on the effect of the electro-mechanical coupling and pharmacological action on human ventricular electrophysiology, calcium dynamics, and active contraction. The most recent models of human ventricular electrophysiology, excitation-contraction coupling, and active contraction were integrated, and the coupled models were calibrated using human experimental data. Simulations were then conducted using the coupled models to quantify the effects of electro-mechanical coupling and drug exposure on electrophysiology and force generation in virtual human ventricular cardiomyocytes and tissue. The resulting calibrated human electro-mechanical models yielded active tension, action potential, and calcium transient metrics that are in agreement with experiments for endocardial, epicardial, and mid-myocardial human samples. Simulation results correctly predicted the inotropic response of different multichannel action reference compounds and demonstrated that the electro-mechanical coupling improves the robustness of repolarisation under drug exposure compared to electrophysiology-only models. They also generated additional evidence to explain the partial mismatch between in-silico and in-vitro experiments on drug-induced electrophysiology changes. The human calibrated and evaluated modelling and simulation framework constructed in this study opens new avenues for future investigations into the complex interplay between the electrical and mechanical cardiac substrates, its modulation by pharmacological action, and its translation to tissue and organ models of cardiac patho-physiology.
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http://dx.doi.org/10.1016/j.pbiomolbio.2020.06.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7848595PMC
January 2021

Nasal sprayed particle deposition in a human nasal cavity under different inhalation conditions.

PLoS One 2019 6;14(9):e0221330. Epub 2019 Sep 6.

Barcelona Supercomputing Center (BSC-CNS), Department of Computer Applications in Science and Engineering, Barcelona, Spain.

Deposition of polydisperse particles representing nasal spray application in a human nasal cavity was performed under transient breathing profiles of sniffing, constant flow, and breath hold. The LES turbulence model was used to describe the fluid phase. Particles were introduced into the flow field with initial spray conditions, including spray cone angle, insertion angle, and initial velocity. Since nasal spray atomizer design determines the particle conditions, fifteen particle size distributions were used, each defined by a log-normal distribution with a different volume mean diameter (Dv50). Particle deposition in the anterior region was approximately 80% when Dv50 > 50μm, and this decreased to 45% as Dv50 decreased to 10μ m for constant and sniff breathing conditions. The decrease in anterior deposition was countered with increased deposition in the middle and posterior regions. The significance of increased deposition in the middle region for drug delivery shows there is potential for nasal delivered drugs to reach the highly vascularised mucosal walls in the main nasal passages. For multiple targeted deposition sites, an optimisation equation was introduced where deposition results of any two targeted sites could be combined and a weighting between 0 to 1 was applied to each targeted site, representing the relative importance of each deposition site.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0221330PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6730903PMC
March 2020

On the chordae structure and dynamic behaviour of the mitral valve.

IMA J Appl Math 2018 Nov 30;83(6):1066-1091. Epub 2018 Aug 30.

School of Mathematics and Statistics, University of Glasgow, UK.

We develop a fluid-structure interaction (FSI) model of the mitral valve (MV) that uses an anatomically and physiologically realistic description of the MV leaflets and chordae tendineae. Three different chordae models-complex, 'pseudo-fibre' and simplified chordae-are compared to determine how different chordae representations affect the dynamics of the MV. The leaflets and chordae are modelled as fibre-reinforced hyperelastic materials, and FSI is modelled using an immersed boundary-finite element method. The MV model is first verified under static boundary conditions against the commercial finite element software ABAQUS and then used to simulate MV dynamics under physiological pressure conditions. Interesting flow patterns and vortex formulation are observed in all three cases. To quantify the highly complex system behaviour resulting from FSI, an energy budget analysis of the coupled MV FSI model is performed. Results show that the complex and pseudo-fibre chordae models yield good valve closure during systole but that the simplified chordae model leads to poorer leaflet coaptation and an unrealistic bulge in the anterior leaflet belly. An energy budget analysis shows that the MV models with complex and pseudo-fibre chordae have similar energy distribution patterns but the MV model with the simplified chordae consumes more energy, especially during valve closing and opening. We find that the complex chordae and pseudo-fibre chordae have similar impact on the overall MV function but that the simplified chordae representation is less accurate. Because a pseudo-fibre chordal structure is easier to construct and less computationally intensive, it may be a good candidate for modelling MV dynamics or interaction between the MV and heart in patient-specific applications.
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http://dx.doi.org/10.1093/imamat/hxy035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6328065PMC
November 2018

Three-dimensional cardiac fibre disorganization as a novel parameter for ventricular arrhythmia stratification after myocardial infarction.

Europace 2019 May;21(5):822-832

Centro Nacional de Investigaciones Cardiovasculares (CNIC), Myocardial Pathophysiology Area, Melchor Fernández Almagro 3, Madrid, Spain.

Aims: Myocardial infarction (MI) alters cardiac fibre organization with unknown consequences on ventricular arrhythmia. We used diffusion tensor imaging (DTI) of three-dimensional (3D) cardiac fibres and scar reconstructions to identify the main parameters associated with ventricular arrhythmia inducibility and ventricular tachycardia (VT) features after MI.

Methods And Results: Twelve pigs with established MI and three controls underwent invasive electrophysiological characterization of ventricular arrhythmia inducibility and VT features. Animal-specific 3D scar and myocardial fibre distribution were obtained from ex vivo high-resolution contrast-enhanced T1 mapping and DTI sequences. Diffusion tensor imaging-derived parameters significantly different between healthy and scarring myocardium, scar volumes, and left ventricular ejection fraction (LVEF) were included for arrhythmia risk stratification and correlation analyses with VT features. Ventricular fibrillation (VF) was the only inducible arrhythmia in 4 out of 12 infarcted pigs and all controls. Ventricular tachycardia was also inducible in the remaining eight pigs during programmed ventricular stimulation. A DTI-based 3D fibre disorganization index (FDI) showed higher disorganization within dense scar regions of VF-only inducible pigs compared with VT inducible animals (FDI: 0.36; 0.36-0.37 vs. 0.32; 0.26-0.33, respectively, P = 0.0485). Ventricular fibrillation induction required lower programmed stimulation aggressiveness in VF-only inducible pigs than VT inducible and control animals. Neither LVEF nor scar volumes differentiated between VF and VT inducible animals. Re-entrant VT circuits were localized within areas of highly disorganized fibres. Moreover, the FDI within heterogeneous scar regions was associated with the median VT cycle length per animal (R2 = 0.5320).

Conclusion: The amount of scar-related cardiac fibre disorganization in DTI sequences is a promising approach for ventricular arrhythmia stratification after MI.
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http://dx.doi.org/10.1093/europace/euy306DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6479517PMC
May 2019

Complex Congenital Heart Disease Associated With Disordered Myocardial Architecture in a Midtrimester Human Fetus.

Circ Cardiovasc Imaging 2018 10;11(10):e007753

Institute of Cardiovascular Science (P.G.-C., A.C.C.), University College London, United Kingdom.

Background: In the era of increasingly successful corrective interventions in patients with congenital heart disease (CHD), global and regional myocardial remodeling are emerging as important sources of long-term morbidity/mortality. Changes in organization of the myocardium in CHD, and in its mechanical properties, conduction, and blood supply, result in altered myocardial function both before and after surgery. To gain a better understanding and develop appropriate and individualized treatment strategies, the microscopic organization of cardiomyocytes, and their integration at a macroscopic level, needs to be completely understood. The aim of this study is to describe, for the first time, in 3 dimensions and nondestructively the detailed remodeling of cardiac microstructure present in a human fetal heart with complex CHD.

Methods And Results: Synchrotron X-ray phase-contrast imaging was used to image an archival midgestation formalin-fixed fetal heart with right isomerism and complex CHD and compare with a control fetal heart. Analysis of myocyte aggregates, at detail not accessible with other techniques, was performed. Macroanatomic and conduction system changes specific to the disease were clearly observable, together with disordered myocyte organization in the morphologically right ventricle myocardium. Electrical activation simulations suggested altered synchronicity of the morphologically right ventricle.

Conclusions: We have shown the potential of X-ray phase-contrast imaging for studying cardiac microstructure in the developing human fetal heart at high resolution providing novel insight while preserving valuable archival material for future study. This is the first study to show myocardial alterations occur in complex CHD as early as midgestation.
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http://dx.doi.org/10.1161/CIRCIMAGING.118.007753DOI Listing
October 2018

Implications of bipolar voltage mapping and magnetic resonance imaging resolution in biventricular scar characterization after myocardial infarction.

Europace 2019 Jan;21(1):163-174

Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Myocardial Pathophysiology Area, Melchor Fernández Almagro, 2, Madrid, Spain.

Aims: We aimed to study the differences in biventricular scar characterization using bipolar voltage mapping compared with state-of-the-art in vivo delayed gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) imaging and ex vivo T1 mapping.

Methods And Results: Ten pigs with established myocardial infarction (MI) underwent in vivo scar characterization using LGE-CMR imaging and high-density voltage mapping of both ventricles using a 3.5-mm tip catheter. Ex vivo post-contrast T1 mapping provided a high-resolution reference. Voltage maps were registered onto the left and right ventricular (LV and RV) endocardium, and epicardium of CMR-based geometries to compare voltage-derived scars with surface-projected 3D scars. Voltage-derived scar tissue of the LV endocardium and the epicardium resembled surface projections of 3D in vivo and ex vivo CMR-derived scars using 1-mm of surface projection distance. The thinner wall of the RV was especially sensitive to lower resolution in vivo LGE-CMR images, in which differences between normalized low bipolar voltage areas and CMR-derived scar areas did not decrease below a median of 8.84% [interquartile range (IQR) (3.58, 12.70%)]. Overall, voltage-derived scars and surface scar projections from in vivo LGE-CMR sequences showed larger normalized scar areas than high-resolution ex vivo images [12.87% (4.59, 27.15%), 18.51% (11.25, 24.61%), and 9.30% (3.84, 19.59%), respectively], despite having used optimized surface projection distances. Importantly, 43.02% (36.54, 48.72%) of voltage-derived scar areas from the LV endocardium were classified as non-enhanced healthy myocardium using ex vivo CMR imaging.

Conclusion: In vivo LGE-CMR sequences and high-density voltage mapping using a conventional linear catheter fail to provide accurate characterization of post-MI scar, limiting the specificity of voltage-based strategies and imaging-guided procedures.
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http://dx.doi.org/10.1093/europace/euy192DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6321957PMC
January 2019

Fully coupled fluid-electro-mechanical model of the human heart for supercomputers.

Int J Numer Method Biomed Eng 2018 12;34(12):e3140

Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain.

In this work, we present a fully coupled fluid-electro-mechanical model of a 50th percentile human heart. The model is implemented on Alya, the BSC multi-physics parallel code, capable of running efficiently in supercomputers. Blood in the cardiac cavities is modeled by the incompressible Navier-Stokes equations and an arbitrary Lagrangian-Eulerian (ALE) scheme. Electrophysiology is modeled with a monodomain scheme and the O'Hara-Rudy cell model. Solid mechanics is modeled with a total Lagrangian formulation for discrete strains using the Holzapfel-Ogden cardiac tissue material model. The three problems are simultaneously and bidirectionally coupled through an electromechanical feedback and a fluid-structure interaction scheme. In this paper, we present the scheme in detail and propose it as a computational cardiac workbench.
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http://dx.doi.org/10.1002/cnm.3140DOI Listing
December 2018

The Effect of Partial Premixing and Heat Loss on the Reacting Flow Field Prediction of a Swirl Stabilized Gas Turbine Model Combustor.

Flow Turbul Combust 2018 13;100(2):503-534. Epub 2017 Sep 13.

2Computer Applications in Science and Engineering Department, Barcelona Supercomputing Center (BSC), Barcelona, Spain.

This work addresses the prediction of the reacting flow field in a swirl stabilized gas turbine model combustor using large-eddy simulation. The modeling of the combustion chemistry is based on laminar premixed flamelets and the effect of turbulence-chemistry interaction is considered by a presumed shape probability density function. The prediction capabilities of the presented combustion model for perfectly premixed and partially premixed conditions are demonstrated. The effect of partial premixing for the prediction of the reacting flow field is assessed by comparison of a perfectly premixed and partially premixed simulation. Even though significant mixture fraction fluctuations are observed, only small impact of the non-perfect premixing is found on the flow field and flame dynamics. Subsequently, the effect of heat loss to the walls is assessed assuming perfectly premixing. The adiabatic baseline case is compared to heat loss simulations with adiabatic and non-adiabatic chemistry tabulation. The results highlight the importance of considering the effect of heat loss on the chemical kinetics for an accurate prediction of the flow features. Both heat loss simulations significantly improve the temperature prediction, but the non-adiabatic chemistry tabulation is required to accurately capture the chemical composition in the reacting layers.
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http://dx.doi.org/10.1007/s10494-017-9848-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6044246PMC
September 2017

Evaluating the roles of detailed endocardial structures on right ventricular haemodynamics by means of CFD simulations.

Int J Numer Method Biomed Eng 2018 09 9;34(9):e3115. Epub 2018 Aug 9.

Barcelona Supercomputing Center (BSC), Barcelona, Spain.

Computational modelling plays an important role in right ventricular (RV) haemodynamic analysis. However, current approaches use smoothed ventricular anatomies. The aim of this study is to characterise RV haemodynamics including detailed endocardial structures like trabeculae, moderator band, and papillary muscles. Four paired detailed and smoothed RV endocardium models (2 male and 2 female) were reconstructed from ex vivo human hearts high-resolution magnetic resonance images. Detailed models include structures with ≥1 mm cross-sectional area. Haemodynamic characterisation was done by computational fluid dynamics simulations with steady and transient inflows, using high-performance computing. The differences between the flows in smoothed and detailed models were assessed using Q-criterion for vorticity quantification, the pressure drop between inlet and outlet, and the wall shear stress. Results demonstrated that detailed endocardial structures increase the degree of intra-ventricular pressure drop, decrease the wall shear stress, and disrupt the dominant vortex creating secondary small vortices. Increasingly turbulent blood flow was observed in the detailed RVs. Female RVs were less trabeculated and presented lower pressure drops than the males. In conclusion, neglecting endocardial structures in RV haemodynamic models may lead to inaccurate conclusions about the pressures, stresses, and blood flow behaviour in the cavity.
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http://dx.doi.org/10.1002/cnm.3115DOI Listing
September 2018

Left Ventricular Trabeculations Decrease the Wall Shear Stress and Increase the Intra-Ventricular Pressure Drop in CFD Simulations.

Front Physiol 2018 30;9:458. Epub 2018 Apr 30.

Barcelona Supercomputing Center (BSC), Barcelona, Spain.

The aim of the present study is to characterize the hemodynamics of left ventricular (LV) geometries to examine the impact of trabeculae and papillary muscles (PMs) on blood flow using high performance computing (HPC). Five pairs of detailed and smoothed LV endocardium models were reconstructed from high-resolution magnetic resonance images (MRI) of human hearts. The detailed model of one LV pair is characterized only by the PMs and few big trabeculae, to represent state of art level of endocardial detail. The other four detailed models obtained include instead endocardial structures measuring ≥1 mm in cross-sectional area. The geometrical characterizations were done using computational fluid dynamics (CFD) simulations with rigid walls and both constant and transient flow inputs on the detailed and smoothed models for comparison. These simulations do not represent a clinical or physiological scenario, but a characterization of the interaction of endocardial structures with blood flow. Steady flow simulations were employed to quantify the pressure drop between the inlet and the outlet of the LVs and the wall shear stress (WSS). Coherent structures were analyzed using the Q-criterion for both constant and transient flow inputs. Our results show that trabeculae and PMs increase the intra-ventricular pressure drop, reduce the WSS and disrupt the dominant single vortex, usually present in the smoothed-endocardium models, generating secondary small vortices. Given that obtaining high resolution anatomical detail is challenging , we propose that the effect of trabeculations can be incorporated into smoothed ventricular geometries by adding a porous layer along the LV endocardial wall. Results show that a porous layer of a thickness of 1.2·10 m with a porosity of 20 kg/m on the smoothed-endocardium ventricle models approximates the pressure drops, vorticities and WSS observed in the detailed models.
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http://dx.doi.org/10.3389/fphys.2018.00458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5936785PMC
April 2018

Large-scale CFD simulations of the transitional and turbulent regime for the large human airways during rapid inhalation.

Comput Biol Med 2016 Feb 17;69:166-80. Epub 2015 Dec 17.

Imperial College London, Department of Aeronautics, Exhibition Road, London SW7 2AZ, UK.

The dynamics of unsteady flow in the human large airways during a rapid inhalation were investigated using highly detailed large-scale computational fluid dynamics on a subject-specific geometry. The simulations were performed to resolve all the spatial and temporal scales of the flow, thanks to the use of massive computational resources. A highly parallel finite element code was used, running on two supercomputers, solving the transient incompressible Navier-Stokes equations on unstructured meshes. Given that the finest mesh contained 350 million elements, the study sets a precedent for large-scale simulations of the respiratory system, proposing an analysis strategy for mean flow, fluctuations and wall shear stresses on a rapid and short inhalation (a so-called sniff). The geometry used encompasses the exterior face and the airways from the nasal cavity, through the trachea and up to the third lung bifurcation; it was derived from a contrast-enhanced computed tomography (CT) scan of a 48-year-old male. The transient inflow produces complex flows over a wide range of Reynolds numbers (Re). Thanks to the high fidelity simulations, many features involving the flow transition were observed, with the level of turbulence clearly higher in the throat than in the nose. Spectral analysis revealed turbulent characteristics persisting downstream of the glottis, and were captured even with a medium mesh resolution. However a fine mesh resolution was found necessary in the nasal cavity to observe transitional features. This work indicates the potential of large-scale simulations to further understanding of airway physiological mechanics, which is essential to guide clinical diagnosis; better understanding of the flow also has implications for the design of interventions such as aerosol drug delivery.
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http://dx.doi.org/10.1016/j.compbiomed.2015.12.003DOI Listing
February 2016

Analysis of hemodynamics and wall mechanics at sites of cerebral aneurysm rupture.

J Neurointerv Surg 2015 Jul 14;7(7):530-6. Epub 2014 May 14.

Department of Interventional Neuroradiology, Inova Fairfax Hospital, Falls Church, Virginia, USA.

Background: It is thought that aneurysms evolve as the result of progressive degradation of the wall in response to abnormal hemodynamics characterized by either high or low wall shear stress (WSS).

Objective: To investigate the effects of these two different hemodynamic pathways in a series of cerebral aneurysms with known rupture sites.

Methods: Nine aneurysms in which the rupture site could be identified in three-dimensional images were analyzed. The WSS distribution was obtained from computational fluid dynamics (CFD) simulations. Internal wall stresses were computed using structural wall models under hemodynamic loads determined by the CFD models. Wall properties (thickness and stiffness) were modulated with the WSS distribution (increased or decreased in regions of high or low WSS) to test possible wall degradation pathways. Rupture probability indices (RPI) were calculated to compare different wall models.

Results: Most rupture sites aligned with the intrasaccular flow stream and downstream of the primary impaction zone. The model that best explained the rupture site (produced higher RPI) in eight of the nine aneurysms (89%) had thinner and stiffer walls in regions of abnormally high WSS. The remaining case (11%) was best explained by a model with thinner and stiffer walls in regions of abnormally low WSS.

Conclusions: Aneurysm rupture seems to be caused by localized degradation and weakening of the wall in response to abnormal hemodynamics. Image-based computational models assuming wall thinning and stiffening in regions of abnormally high WSS were able to explain most of the observed rupture sites.
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http://dx.doi.org/10.1136/neurintsurg-2014-011247DOI Listing
July 2015

Coupled electromechanical model of the heart: Parallel finite element formulation.

Int J Numer Method Biomed Eng 2012 Jan;28(1):72-86

BSC-CNS, Barcelona Supercomputing Center, Barcelona, Spain.

In this paper, a highly parallel coupled electromechanical model of the heart is presented and assessed. The parallel-coupled model is thoroughly discussed, with scalability proven up to hundreds of cores. This work focuses on the mechanical part, including the constitutive model (proposing some modifications to pre-existent models), the numerical scheme and the coupling strategy. The model is next assessed through two examples. First, the simulation of a small piece of cardiac tissue is used to introduce the main features of the coupled model and calibrate its parameters against experimental evidence. Then, a more realistic problem is solved using those parameters, with a mesh of the Oxford ventricular rabbit model. The results of both examples demonstrate the capability of the model to run efficiently in hundreds of processors and to reproduce some basic characteristic of cardiac deformation.
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http://dx.doi.org/10.1002/cnm.1494DOI Listing
January 2012