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Fluid dynamics of the heart

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https://www.readbyqxmd.com/read/28210935/the-effect-of-fluid-resuscitation-on-the-effective-circulating-volume-in-patients-undergoing-liver-surgery-a-post-hoc-analysis-of-a-randomized-controlled-trial
#1
Jaap Jan Vos, A F Kalmar, H G D Hendriks, J Bakker, T W L Scheeren
To assess the significance of an analogue of the mean systemic filling pressure (Pmsa) and its derived variables, in providing a physiology based discrimination between responders and non-responders to fluid resuscitation during liver surgery. A post-hoc analysis of data from 30 patients undergoing major hepatic surgery was performed. Patients received 15 ml kg(-1) fluid in 30 min. Fluid responsiveness (FR) was defined as an increase of 20% or greater in cardiac index, measured by FloTrac-Vigileo(®). Dynamic preload variables (pulse pressure variation and stroke volume variation: PPV, SVV) were recorded additionally...
February 16, 2017: Journal of Clinical Monitoring and Computing
https://www.readbyqxmd.com/read/28181776/cardiovascular-adjustments-to-heat-stress-during-prolonged-exercise
#2
Luna Rizzo, Martin W Thompson
Prolonged effort in hot environments is increasing popular in extreme sports. The number of long distance athletes taking part in races in extremely warm condition, as in deserts, is larger than in the past and also the race distances are increased thus. The demanding for the heart function are higher than those challenged in the past only by few athletes and in easier conditions. This puts news challenges on the professional involved in these activities and there is a need to better understand how the cardiocirculatory system responses in these extreme environmental conditions...
February 8, 2017: Journal of Sports Medicine and Physical Fitness
https://www.readbyqxmd.com/read/28168706/flow-field-simulations-and-hemolysis-estimates-for-the-food-and-drug-administration-critical-path-initiative-centrifugal-blood-pump
#3
Margaret L Heck, Allen Yen, Trevor A Snyder, Edgar A O'Rear, Dimitrios V Papavassiliou
The design of blood pumps for use in ventricular assist devices, which provide life-saving circulatory support in patients with heart failure, require remarkable precision and attention to detail to replicate the functionality of the native heart. The United States Food and Drug Administration (FDA) initiated a Critical Path Initiative to standardize and facilitate the use of computational fluid dynamics in the study and development of these devices. As a part of the study, a simplified centrifugal blood pump model generated by computer-aided design was released to universities and laboratories nationwide...
February 7, 2017: Artificial Organs
https://www.readbyqxmd.com/read/28155704/the-movement-and-deposition-of-pm2-5-in-the-upper-respiratory-tract-for-the-patients-with-heart-failure-an-elementary-cfd-study
#4
Tiantian Zhang, Bin Gao, Zhixiang Zhou, Yu Chang
BACKGROUND: PM2.5 is an important factor to affect the patients with respiratory and cardiovascular diseases. Clinical studies have found that the morbidity and mortality of patients with heart failure (HF) have a close relationship with the movement and deposition state of PM2.5. One reason is that the breathing pattern of patients with HF has obvious difference with healthy people, however the effect caused by these differences on the distribution regularity of PM2.5 in the respiratory tract is still unclear...
December 28, 2016: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28155672/the-study-on-hemodynamic-effect-of-series-type-lvad-on-aortic-blood-flow-pattern-a-primary-numerical-study
#5
Qi Zhang, Bin Gao, Yu Chang
BACKGROUND: Left ventricular assist device (LVAD) has become an alternative treatment for end-stage heart failure patients. Series type of LVAD, as a novel LVAD, has attracted more and more attention. The hemodynamic effects of series type LVAD on aortic blood pattern are considered as its important characteristics; however, the precise mechanism of it is still unclear. METHODS: To clarify the hemodynamic effects of series type LVAD on aortic blood flow pattern, a comparative study on the aortic blood flow pattern and hemodynamic states were carried out numerically for two cases, including series type LVAD support and normal condition...
December 28, 2016: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28072930/left-ventricular-outflow-tract-obstruction-be-prepared
#6
J S Evans, S J Huang, A S McLean, M Nalos
The current trend to treat hypotension in critically ill patients is to place a greater emphasis on inotropic support and less on fluid resuscitation in order to limit the potential harm from fluid overload. This combination may trigger left ventricular outflow tract obstruction (LVOTO) in susceptible patients. Although LVOTO is classically described in patients with hypertrophic cardiomyopathy it has been reported in other conditions including septic shock, apical ballooning syndrome, myocardial infarction, respiratory failure, and post valvular surgery...
January 2017: Anaesthesia and Intensive Care
https://www.readbyqxmd.com/read/28039243/electrical-impedance-tomography-for-non-invasive-assessment-of-stroke-volume-variation-in-health-and-experimental-lung-injury
#7
C J C Trepte, C Phillips, J Solà, A Adler, B Saugel, S Haas, S H Bohm, D A Reuter
BACKGROUND: Functional imaging by thoracic electrical impedance tomography (EIT) is a non-invasive approach to continuously assess central stroke volume variation (SVV) for guiding fluid therapy. The early available data were from healthy lungs without injury-related changes in thoracic impedance as a potentially influencing factor. The aim of this study was to evaluate SVV measured by EIT (SVVEIT) against SVV from pulse contour analysis (SVVPC) in an experimental animal model of acute lung injury at different lung volumes...
January 2017: British Journal of Anaesthesia
https://www.readbyqxmd.com/read/28038944/numerical-simulation-of-mitral-valve-prolapse-considering-the-effect-of-left-ventricle
#8
Seyedvahid Khodaei, Nasser Fatouraee, Malikeh Nabaei
Heart failure is one of the most important issues that has been investigated in recent research studies. Variations that occur in apparatus of mitral valve, such as chordae tendineaea rupture, can affect the valve function during ventricular contraction and lead to regurgitation from the left ventricle into the left atrium. One method for understanding mitral valve function in such conditions is computational analysis. In this paper, we develop a finite element model of mitral valve prolapse, considering the direct effect of left ventricular motion on blood flow interacting with the mitral valve...
December 28, 2016: Mathematical Biosciences
https://www.readbyqxmd.com/read/28033200/lvad-outflow-graft-angle-and-thrombosis-risk
#9
Alberto Aliseda, Venkat Keshav Chivukula, Patrick Mcgah, Anthony R Prisco, Jennifer A Beckman, Guilherme J M Garcia, Nahush A Mokadam, Claudius Mahr
This study quantifies thrombogenic potential (TP) of a wide range of left ventricular assist device (LVAD) outflow graft anastomosis angles through state-of-the-art techniques: 3D imaged-based patient-specific models created via virtual surgery and unsteady computational fluid dynamics with Lagrangian particle tracking. This study aims at clarifying the influence of a single parameter (outflow graft angle) on the thrombogenesis associated with flow patterns in the aortic root after LVAD implantation. This is an important and poorly-understood aspect of LVAD therapy, because several studies have shown strong inter and intrapatient thrombogenic variability and current LVAD implantation strategies do not incorporate outflow graft angle optimization...
January 2017: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
https://www.readbyqxmd.com/read/27905492/high-fidelity-computational-simulation-of-thrombus-formation-in-thoratec-heartmate-ii-continuous-flow-ventricular-assist-device
#10
Wei-Tao Wu, Fang Yang, Jingchun Wu, Nadine Aubry, Mehrdad Massoudi, James F Antaki
Continuous flow ventricular assist devices (cfVADs) provide a life-saving therapy for severe heart failure. However, in recent years, the incidence of device-related thrombosis (resulting in stroke, device-exchange surgery or premature death) has been increasing dramatically, which has alarmed both the medical community and the FDA. The objective of this study was to gain improved understanding of the initiation and progression of thrombosis in one of the most commonly used cfVADs, the Thoratec HeartMate II...
December 1, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27904980/a-resolved-two-way-coupled-cfd-6-dof-approach-for-predicting-embolus-transport-and-the-embolus-trapping-efficiency-of-ivc-filters
#11
Kenneth I Aycock, Robert L Campbell, Keefe B Manning, Brent A Craven
Inferior vena cava (IVC) filters are medical devices designed to provide a mechanical barrier to the passage of emboli from the deep veins of the legs to the heart and lungs. Despite decades of development and clinical use, IVC filters still fail to prevent the passage of all hazardous emboli. The objective of this study is to (1) develop a resolved two-way computational model of embolus transport, (2) provide verification and validation evidence for the model, and (3) demonstrate the ability of the model to predict the embolus-trapping efficiency of an IVC filter...
November 30, 2016: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/27878837/thrombotic-depositions-on-right-impeller-of-double-ended-centrifugal-total-artificial-heart-in-vivo
#12
Jamshid H Karimov, David J Horvath, Shinji Okano, Mark Goodin, Gengo Sunagawa, Nicole Byram, Nader Moazami, Leonard A R Golding, Kiyotaka Fukamachi
The development of total artificial heart devices is a complex undertaking that includes chronic biocompatibility assessment of the device. It is considered particularly important to assess whether device design and features can be compatible long term in a biological environment. As part of the development program for the Cleveland Clinic continuous-flow total artificial heart (CFTAH), we evaluated the device for signs of thrombosis and biological material deposition in four animals that had achieved the intended 14-, 30-, or 90-day durations in each respective experiment...
November 23, 2016: Artificial Organs
https://www.readbyqxmd.com/read/27873180/pledget-armed-sutures-affect-the-haemodynamic-performance-of-biologic-aortic-valve-substitutes-a-preliminary-experimental-and-computational-study
#13
Claudio Capelli, Chiara Corsini, Dario Biscarini, Francesco Ruffini, Francesco Migliavacca, Alfred Kocher, Guenther Laufer, Andrew M Taylor, Silvia Schievano, Martin Andreas, Gaetano Burriesci, Claus Rath
Surgical aortic valve replacement is the most common procedure of choice for the treatment of severe aortic stenosis. Bioprosthetic valves are traditionally sewed-in the aortic root by means of pledget-armed sutures during open-heart surgery. Recently, novel bioprostheses which include a stent-based anchoring system have been introduced to allow rapid implantation, therefore reducing the duration and invasiveness of the intervention. Different effects on the hemodynamics were clinically reported associated with the two technologies...
November 21, 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27866678/patient-specific-cfd-models-for-intraventricular-flow-analysis-from-3d-ultrasound-imaging-comparison-of-three-clinical-cases
#14
A M Bavo, A M Pouch, J Degroote, J Vierendeels, J H Gorman, R C Gorman, P Segers
BACKGROUND: As the intracardiac flow field is affected by changes in shape and motility of the heart, intraventricular flow features can provide diagnostic indications. Ventricular flow patterns differ depending on the cardiac condition and the exploration of different clinical cases can provide insights into how flow fields alter in different pathologies. METHODS: In this study, we applied a patient-specific computational fluid dynamics model of the left ventricle and mitral valve, with prescribed moving boundaries based on transesophageal ultrasound images for three cardiac pathologies, to verify the abnormal flow patterns in impaired hearts...
January 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/27863743/in-vitro-and-in-silico-approaches-to-quantify-the-effects-of-the-mitraclip-%C3%A2-system-on-mitral-valve-function
#15
Francesco Sturla, Riccardo Vismara, Michal Jaworek, Emiliano Votta, Paolo Romitelli, Omar A Pappalardo, Federico Lucherini, Carlo Antona, Gianfranco B Fiore, Alberto Redaelli
Mitraclip(®) implantation is widely used as a valid alternative to conventional open-chest surgery in high-risk patients with severe mitral valve (MV) regurgitation. Although effective in reducing mitral regurgitation (MR) in the majority of cases, the clip implantation produces a double-orifice area that can result in altered MV biomechanics, particularly in term of hemodynamics and mechanical stress distribution on the leaflets. In this scenario, we combined the consistency of in vitro experimental platforms with the versatility of numerical simulations to investigate clip impact on MV functioning...
January 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/27858374/prediction-of-fluid-responsiveness-an-update
#16
REVIEW
Xavier Monnet, Paul E Marik, Jean-Louis Teboul
In patients with acute circulatory failure, the decision to give fluids or not should not be taken lightly. The risk of overzealous fluid administration has been clearly established. Moreover, volume expansion does not always increase cardiac output as one expects. Thus, after the very initial phase and/or if fluid losses are not obvious, predicting fluid responsiveness should be the first step of fluid strategy. For this purpose, the central venous pressure as well as other "static" markers of preload has been used for decades, but they are not reliable...
December 2016: Annals of Intensive Care
https://www.readbyqxmd.com/read/27844463/fluid-structure-interaction-study-of-transcatheter-aortic-valve-dynamics-using-smoothed-particle-hydrodynamics
#17
Wenbin Mao, Kewei Li, Wei Sun
Computational modeling of heart valve dynamics incorporating both fluid dynamics and valve structural responses has been challenging. In this study, we developed a novel fully-coupled fluid-structure interaction (FSI) model using smoothed particle hydrodynamics (SPH). A previously developed nonlinear finite element (FE) model of transcatheter aortic valves (TAV) was utilized to couple with SPH to simulate valve leaflet dynamics throughout the entire cardiac cycle. Comparative simulations were performed to investigate the impact of using FE-only models vs...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27832045/proof-of-concept-of-an-endoscopic-sutureless-valve-sizer
#18
Marco Vola, Juan Pablo Maureira, Vito Giovanni Ruggieri, Jean-François Fuzellier, Salvatore Campisi, Jean-Pierre Favre, Antoine Gerbay, Thierry A Folliguet
OBJECTIVE: In this paper, we present an endoscopic expandable sizer conceived to allow thoracoscopic aortic valve replacement with a sutureless prosthesis using a dynamic sizing of the aortic annulus. METHODS: Ten aortic torsos were prepared using a five-trocar thoracoscopic setting. Once the aortotomy was performed and the aortic valve leaflets removed, the technical feasibility of the endoscopic sizing (introduction into the trocar, expansion into the aortic annulus, determination of the valve size, and retraction) with the device was assessed...
September 2016: Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery
https://www.readbyqxmd.com/read/27824560/assessing-the-performance-of-ultrafast-vector-flow-imaging-in-the-neonatal-heart-via-multiphysics-modeling-and-in-vitro-experiments
#19
Joris Van Cauwenberge, Lasse Lovstakken, Solveig Fadnes, Alfonso Rodriguez-Morales, Jan Vierendeels, Patrick Segers, Abigail Swillens
Ultrafast vector flow imaging would benefit newborn patients with congenital heart disorders, but still requires thorough validation before translation to clinical practice. This paper investigates 2-D speckle tracking (ST) of intraventricular blood flow in neonates when transmitting diverging waves at ultrafast frame rate. Computational and in vitro studies enabled us to quantify the performance and identify artifacts related to the flow and the imaging sequence. First, synthetic ultrasound images of a neonate's left ventricular flow pattern were obtained with the ultrasound simulator Field II by propagating point scatterers according to 3-D intraventricular flow fields obtained with computational fluid dynamics (CFD)...
November 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27815409/a-new-beating-heart-mitral-and-aortic-valve-assessment-model-with-implications-for-valve-intervention-training
#20
Wobbe Bouma, Jayant S Jainandunsing, Arash Khamooshian, Pim van der Harst, Massimo A Mariani, Ehsan Natour
OBJECTIVES: A thorough understanding of mitral and aortic valve motion dynamics is essential in mastering the skills necessary for performing successful valve intervention (open or transcatheter repair or replacement). We describe a reproducible and versatile beating-heart mitral and aortic valve assessment and valve intervention training model in human cadavers. METHODS: The model is constructed by bilateral ligation of the pulmonary veins, ligation of the supra-aortic arteries, creating a shunt between the descending thoracic aorta and the left atrial appendage with a vascular prosthesis, anastomizing a vascular prosthesis to the apex and positioning an intra-aortic balloon pump (IABP) in the vascular prosthesis, cross-clamping the descending thoracic aorta, and finally placing a fluid line in the shunt prosthesis...
November 3, 2016: Interactive Cardiovascular and Thoracic Surgery
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