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Fluid dynamics of the heart

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https://www.readbyqxmd.com/read/29423504/nonlinear-dynamics-of-dacron-aortic-prostheses-conveying-pulsatile-flow
#1
Eleonora Tubaldi, Michael Paidoussis, Marco Amabili
This study addresses the dynamic response to pulsatile physiological blood flow and pressure of a woven Dacron graft currently used in thoracic aortic surgery. The model of the prosthesis assumes a cylindrical orthotropic shell described by means of nonlinear Novozhilov shell theory. The blood flow is modeled as Newtonian pulsatile flow, and unsteady viscous effects are included. Coupled fluid-structure Lagrange equations for open systems with wave propagation subject to pulsatile flow are applied. Physiological waveforms of blood pressure and velocity are approximated with the first eight harmonics of the corresponding Fourier series...
February 8, 2018: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/29373336/competing-flow-between-partial-circulatory-support-and-native-cardiac-output-a-clinical-computational-fluid-dynamics-study
#2
Jennifer Engelke, Christof Karmonik, Fabian Rengier, Sasan Partovi, Aron-Frederik Popov, Anja Osswald, Rawa Arif, Bastian Schmack, Philip Raake, André R Simon, Andreas Doesch, Alexander Weymann, Joachim Lotz, Matthias Karck, Arjang Ruhparwar
Partial circulatory support is a promising concept for the treatment of heart failure patients. A better understanding of induced hemodynamic changes is essential for optimizing treatment efficacy. Computational fluid dynamics (CFD) is an alternative method to gain insight into flow phenomena difficult to obtain in vivo. In 10 patients implanted with a Circulite Synergy Micro-pump (HeartWare) (a continuous flow partial circulatory assist device connecting the left atrium to the right subclavian artery), transient CFD simulations were performed...
October 25, 2017: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
https://www.readbyqxmd.com/read/29368625/perioperative-fluid-management-in-kidney-transplantation-a-black-box
#3
REVIEW
Maria Helena Calixto Fernandes, Thomas Schricker, Sheldon Magder, Roupen Hatzakorzian
The incidence of delayed graft function in patients undergoing kidney transplantation remains significant. Optimal fluid therapy has been shown to decrease delayed graft function after renal transplantation. Traditionally, the perioperative volume infusion regimen in this patient population has been guided by central venous pressure as an estimation of the patient's volume status and mean arterial pressure, but this is based on sparse evidence from mostly retrospective observational studies. Excessive volume infusion to the point of no further fluid responsiveness can damage the endothelial glycocalyx and is no longer considered to be the best approach...
January 25, 2018: Critical Care: the Official Journal of the Critical Care Forum
https://www.readbyqxmd.com/read/29368394/complex-coronary-bifurcation-treatment-by-a-novel-stenting-technique-bench-test-fluid-dynamic-study-and-clinical-outcomes
#4
Gianluca Rigatelli, Marco Zuin, Fabio Dell'Avvocata, Dobrin Vassilev, Ramesh Daggubati, Thach Nguyen, Minh Trí Nhân Nguyễn, Nicolas Foin
OBJECTIVES: We assess the mid-term outcomes of ultrathin biodegradable polymer double stenting using a very minimal crushing (Nano-Crush) technique in large complex coronary bifurcation. BACKGROUND: Complex bifurcations have been suggested to be better approached by a planned double stent technique. METHODS: Two hundred and five consecutive patients (107 males and 98 females) referred for large complex coronary bifurcation percutaneous coronary interventions were enrolled...
January 25, 2018: Catheterization and Cardiovascular Interventions
https://www.readbyqxmd.com/read/29354002/cerebrospinal-fluid-dynamics-in-patients-with-multiple-sclerosis-the-role-of-phase-contrast-mri-in-the-differential-diagnosis-of-active-and-chronic-disease
#5
Serkan Öner, Ayşegül Sağır Kahraman, Cemal Özcan, Zeynep Maraş Özdemir, Serkan Ünlü, Özden Kamışlı, Zülal Öner
Objective: Multiple sclerosis (MS) is an inflammatory disease characterized by demyelinating plaques in the white matter. Chronic cerebrospinal venous insufficiency (CCSVI) has been proposed as a new hypothesis for the etiopathogenesis of MS disease. MS-CCSVI includes a significant decrease of cerebrospinal fluid (CSF) flow through the cerebral aqueduct secondary to an impaired venous outflow from the central nervous system. This study aimed to determine whether CSF flow dynamics are affected in MS patients and the contributions to differential diagnosis in active and chronic disease using phase-contrast magnetic resonance imaging (PC-MRI)...
January 2018: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
https://www.readbyqxmd.com/read/29305610/flow-structure-interaction-simulations-of-the-aortic-heart-valve-at-physiologic-conditions-the-role-of-tissue-constitutive-model
#6
Anvar Gilmanov, Henryk Stolarski, Fotis Sotiropoulos
The blood flow patterns in the region around the aortic valve depend on the geometry of the aorta and on the complex flow-structure interaction between the pulsatile flow and the valve leaflets. Consequently, the flow depends strongly on the constitutive properties of the tissue, which can be expected to vary between healthy and diseased heart valves or native and prosthetic valves. In this work we seek to demonstrate the role of tissue constitutive model on aortic valve hemodynamics. We employ the Curvilinear Immersed Boundary - Finite Element - Fluid Structure Interaction (CURVIB-FE-FSI) method developed by Gilmanov et al...
January 5, 2018: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/29285347/patient-specific-simulations-for-planning-treatment-in-congenital-heart-disease
#7
Claudio Capelli, Emilie Sauvage, Giuliano Giusti, Giorgia M Bosi, Hopewell Ntsinjana, Mario Carminati, Graham Derrick, Jan Marek, Sachin Khambadkone, Andrew M Taylor, Silvia Schievano
Patient-specific computational models have been extensively developed over the last decades and applied to investigate a wide range of cardiovascular problems. However, translation of these technologies into clinical applications, such as planning of medical procedures, has been limited to a few single case reports. Hence, the use of patient-specific models is still far from becoming a standard of care in clinical practice. The aim of this study is to describe our experience with a modelling framework that allows patient-specific simulations to be used for prediction of clinical outcomes...
February 6, 2018: Interface Focus
https://www.readbyqxmd.com/read/29262474/-clinical-application-of-electrical-velocimetry-in-monitoring-pediatric-blood-volume-after-cardiopulmonary-bypass
#8
J R Xue, B Li
Objective: To investigate the clinical applicability of electrical velocimetry (EV) in monitoring pediatric blood volume after cardiopulmonary bypass. Method: Between July 2016 and November 2016, 60 children with congenital heart disease were divided into EV group and traditional central venous pressure (CVP) group randomly. For EV group, the volume of fluid and vascular active medicine was adjusted according to the monitoring stroke volume variation (SVV) hemodynamic parameters. Whereas for CVP group empirical volume of fluid infusion was managed by the monitoring traditional hemodynamic parameters such as CVP, blood pressure, heart rate, urine volume and blood gas analysis...
December 2, 2017: Zhonghua Er Ke za Zhi. Chinese Journal of Pediatrics
https://www.readbyqxmd.com/read/29229579/investigation-of-the-pulsatility-of-cerebrospinal-fluid-using-cardiac-gated-intravoxel-incoherent-motion-imaging
#9
Anton S Becker, Andreas Boss, Markus Klarhoefer, Tim Finkenstaedt, Moritz C Wurnig, Cristina Rossi
The quantitative and non-invasive monitoring of cerebrospinal fluid (CSF) dynamics and composition may have high clinical relevance in the management of CSF disorders. In this study, we propose the use of the Intravoxel Incoherent Motion (IVIM) MRI for obtaining simultaneous measurements of CSF self-diffusion and fluid circulation. The rationale for this study was that turbulent fluid and mesoscopic fluid fluctuations can be modeled in a first approximation as a fast diffusion process. In this case, we expect that the fast fluid circulation and slower molecular diffusion dynamics can be quantified, assuming a bi-exponential attenuation pattern of the diffusion-weighted signal in MRI...
December 8, 2017: NeuroImage
https://www.readbyqxmd.com/read/29203173/evaluation-of-the-dynamic-predictors-of-fluid-responsiveness-in-dogs-receiving-goal-directed-fluid-therapy
#10
Maja J Drozdzynska, Yu-Mei Chang, Giacomo Stanzani, Ludovic Pelligand
OBJECTIVES: Goal-directed fluid therapy (GDFT) based on pulse pressure variation (PPV) was used in anaesthetized dogs undergoing abdominal surgeries. The aims were 1) to evaluate the success rate of the PPV ≥13% in detecting fluid responsiveness [delta stroke volume (ΔSV) ≥10%]; 2) to assess the correlation between PPV, systolic pressure variation (SPV), Plethysmograph Variability Index (PVI) and central venous pressure (CVP) and 3) to establish the threshold value for the PVI that would predict a PPV value of ≥13% and indirectly discriminate responders from nonresponders to fluid therapy...
January 2018: Veterinary Anaesthesia and Analgesia
https://www.readbyqxmd.com/read/29183945/organ-size-control-via-hydraulically-gated-oscillations
#11
Teresa Ruiz-Herrero, Kévin Alessandri, Basile V Gurchenkov, Pierre Nassoy, L Mahadevan
Hollow vesicular tissues of various sizes and shapes arise in biological organs such as ears, guts, hearts, brains and even entire organisms. Regulating their size and shape is crucial for their function. Although chemical signaling has been thought to play a role in the regulation of cellular processes that feed into larger scales, it is increasingly recognized that mechanical forces are involved in the modulation of size and shape at larger length scales. Motivated by a variety of examples of tissue cyst formation and size control that show simultaneous growth and size oscillations, we create a minimal theoretical framework for the growth and dynamics of a soft, fluid-permeable, spherical shell...
December 1, 2017: Development
https://www.readbyqxmd.com/read/29181891/fluid-structure-interaction-of-a-pulsatile-flow-with-an-aortic-valve-model-a-combined-experimental-and-numerical-study
#12
J Sigüenza, D Pott, S Mendez, S J Sonntag, T A S Kaufmann, U Steinseifer, F Nicoud
The complex fluid-structure interaction problem associated with the flow of blood through a heart valve with flexible leaflets is investigated both experimentally and numerically. In the experimental test rig, a pulse duplicator generates a pulsatile flow through a biomimetic rigid aortic root where a model of aortic valve with polymer flexible leaflets is implanted. High-speed recordings of the leaflets motion and Particle Image Velocimetry measurements were performed together to investigate the valve kinematics and the dynamics of the flow...
November 27, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29161412/fluid-dynamics-in-heart-development-effects-of-hematocrit-and-trabeculation
#13
Nicholas A Battista, Andrea N Lane, Jiandong Liu, Laura A Miller
Recent in vivo experiments have illustrated the importance of understanding the haemodynamics of heart morphogenesis. In particular, ventricular trabeculation is governed by a delicate interaction between haemodynamic forces, myocardial activity, and morphogen gradients, all of which are coupled to genetic regulatory networks. The underlying haemodynamics at the stage of development in which the trabeculae form is particularly complex, given the balance between inertial and viscous forces. Small perturbations in the geometry, scale, and steadiness of the flow can lead to changes in the overall flow structures and chemical morphogen gradients, including the local direction of flow, the transport of morphogens, and the formation of vortices...
November 16, 2017: Mathematical Medicine and Biology: a Journal of the IMA
https://www.readbyqxmd.com/read/29124548/development-of-an-experimental-and-digital-cardiovascular-arterial-model-for-transient-hemodynamic-and-postural-change-studies-a-preliminary-framework-analysis
#14
Rodward L Hewlin, John P Kizito
The ultimate goal of the present work is to aid in the development of tools to assist in the treatment of cardiovascular disease. Gaining an understanding of hemodynamic parameters for medical implants allow clinicians to have some patient-specific proposals for intervention planning. In the present work an experimental and digital computational fluid dynamics (CFD) arterial model consisting of a number of major arteries (aorta, carotid bifurcation, cranial, femoral, jejunal, and subclavian arteries) were fabricated to study: (1) the effects of local hemodynamics (flow parameters) on global hemodynamics (2) the effects of transition from bedrest to upright position (postural change) on hemodynamics, and (3) diffusion of dye (medical drug diffusion simulation) in the arterial system via experimental and numerical techniques...
November 9, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/29124390/the-liebau-phenomenon-a-translational-approach-to-new-paradigms-of-csf-circulation-and-related-flow-disturbances
#15
Pierluigi Longatti
PURPOSE: The aim of the study is to provide a comparison between Liebau's effect, underlying the working principles of impedance pumps, and the cerebrospinal fluid (CSF) circulation. METHODS: Gerhard Liebau was a cardiologist with a specific interest in severe aortic regurgitation. Such interest drew his scientific attention to the flow-driven efficiency of valveless pumps. During one of his experiments, he assembled two rubber tubes of different sizes and documented how water could be aspirated against gravity when the tube of larger diameter underwent rhythmic compression...
November 9, 2017: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/29122962/frequent-drinking-of-small-volumes-improves-cardiac-function-and-survival-in-rats-with-chronic-heart-failure
#16
Can Zheng, Meihua Li, Toru Kawada, Masashi Inagaki, Kazunori Uemura, Masaru Sugimachi
Fluid retention is the main reason for the high hospitalization rate among patients with chronic heart failure (CHF). Given the lack of knowledge about fluid intake regulation and its consequences in patients with CHF, current guidelines do not provide clear direction for fluid management. Using a rat model of CHF, we investigated altering drinking behaviors and explored fluid management strategies. CHF was induced by ligating the left anterior descending coronary arteries in 8-week-old, male, Sprague-Dawley rats...
November 2017: Physiological Reports
https://www.readbyqxmd.com/read/29098290/fluid-structure-interaction-models-of-bicuspid-aortic-valves-the-effects-of-non-fused-cusp-angles
#17
Karin Lavon, Rotem Halevi, Gil Marom, Sagit Ben Zekry, Ashraf Hamdan, Hans Joachim Schäfers, Ehud Raanani, Rami Haj-Ali
Bicuspid aortic valve (BAV) is the most common type of congenital heart disease, occurring in 0.5-2% of the population, where the valve has only two rather than the three normal cusps. Valvular pathologies, such as aortic regurgitation and aortic stenosis, are associated with BAVs, thereby increasing the need for a better understanding of BAV kinematics and geometrical characteristics. The aim of this study is to investigate the influence of the non-fused cusp (NFC) angle in BAV type-1 configuration on the valve's structural and hemodynamic performance...
November 2, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/29091053/multiscale-network-representation-of-physiological-time-series-for-early-prediction-of-sepsis
#18
Supreeth P Shashikumar, Qiao Li, Gari D Clifford, Shamim Nemati
Objective and Approach: Sepsis, a dysregulated immune-mediated host response to infection, is the leading cause of morbidity and mortality in critically ill patients. Indices of heart rate variability and complexity (such as entropy) have been proposed as surrogate markers of neuro-immune system dysregulation with diseases such as sepsis. However, these indices only provide an average, one dimensional description of complex neuro-physiological interactions. We propose a novel multiscale network construction and analysis method for multivariate physiological time series, and demonstrate its utility for early prediction of sepsis...
November 30, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29082600/analysis-of-left-ventricular-fluid-dynamics-in-dilated-cardiomyopathy-by-echocardiographic-particle-image-velocimetry
#19
Chouchou Tang, Yizhong Zhu, Jing Zhang, Chengcheng Niu, Dan Liu, Yacong Liao, Lijun Zhu, Qinghai Peng
OBJECTIVE: The aim was to analyze left ventricular (LV) fluid dynamics in dilated cardiomyopathy (DCM) by using echocardiographic particle image velocimetry (E-PIV). METHODS: Twenty patients with DCM and twenty healthy volunteers were examined. LV ultrasound contrast was administered by intravenous bolus injection. At least three dynamic contrast-enhanced echocardiographic images of cardiac cycles from apical three-chamber view and four-chamber view were obtained...
January 2018: Echocardiography
https://www.readbyqxmd.com/read/29080776/comprehensive-computational-assessment-of-blood-flow-characteristics-of-left-ventricle-based-on-in-vivo-mri-in-presence-of-artificial-myocardial-infarction
#20
Ali Imanparast, Nasser Fatouraee, Farhad Sharif
BACKGROUND: Understanding the effects of cardiac diseases on the heart's functionality which is the purpose of many biomedical researches, directly affects the diagnostic and therapeutic methods. Myocardial infarction (MI) is a common complication of cardiac ischemia, however, the impact of MI on the left ventricle (LV) flow patterns has not been widely considered by computational fluid dynamics studies thus far. METHODS: In this study, we present an insightful numerical method that creates an artificial MI on an image-based fluid-structure interactional model of normal LV to investigate its influence on the flow in comparison with the normal case...
October 26, 2017: Mathematical Biosciences
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