Journal articles: 'Cardiovascular fluid mechanic'

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Oldenburg, Jan, Julian Renkewitz, Michael Stiehm, and Klaus-Peter Schmitz. "Contributions towards Data driven Deep Learning methods to predict Steady State Fluid Flow in mechanical Heart Valves." Current Directions in Biomedical Engineering 7, no. 2 (October 1, 2021): 625–28. http://dx.doi.org/10.1515/cdbme-2021-2159.

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Abstract It is commonly accepted that hemodynamic situation is related with cardiovascular diseases as well as clinical post-procedural outcome. In particular, aortic valve stenosis and insufficiency are associated with high shear flow and increased pressure loss. Furthermore, regurgitation, high shear stress and regions of stagnant blood flow are presumed to have an impact on clinical result. Therefore, flow field assessment to characterize the hemodynamic situation is necessary for device evaluation and further design optimization. In-vitro as well as in-silico fluid mechanics methods can be used to investigate the flow through prostheses. In-silico solutions are based on mathematical equitation’s which need to be solved numerically (Computational Fluid Dynamics - CFD). Fundamentally, the flow is physically described by Navier-Stokes. CFD often requires high computational cost resulting in long computation time. Techniques based on deep-learning are under research to overcome this problem. In this study, we applied a deep-learning strategy to estimate fluid flows during peak systolic steady-state blood flows through mechanical aortic valves with varying opening angles in randomly generated aortic root geometries. We used a data driven approach by running 3,500 two dimensional simulations (CFD). The simulation data serves as training data in a supervised deep learning framework based on convolutional neural networks analogous to the U-net architecture. We were able to successfully train the neural network using the supervised data driven approach. The results showing that it is feasible to use a neural network to estimate physiological flow fields in the vicinity of prosthetic heart valves (Validation error below 0.06), by only giving geometry data (Image) into the Network. The neural network generates flow field prediction in real time, which is more than 2500 times faster compared to CFD simulation. Accordingly, there is tremendous potential in the use of AIbased approaches predicting blood flows through heart valves on the basis of geometry data, especially in applications where fast fluid mechanic predictions are desired.

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Wiputra, Hadi, Ching Kit Chen, Elias Talbi, Guat Ling Lim, Sanah Merchant Soomar, Arijit Biswas, Citra Nurfarah Zaini Mattar, David Bark, Hwa Liang Leo, and Choon Hwai Yap. "Human fetal hearts with tetralogy of Fallot have altered fluid dynamics and forces." American Journal of Physiology-Heart and Circulatory Physiology 315, no. 6 (December 1, 2018): H1649—H1659. http://dx.doi.org/10.1152/ajpheart.00235.2018.

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Studies have suggested the effect of blood flow forces in pathogenesis and progression of some congenital heart malformations. It is therefore of interest to study the fluid mechanic environment of the malformed prenatal heart, such as the tetralogy of Fallot (TOF), especially when little is known about fetal TOF. In this study, we performed patient-specific ultrasound-based flow simulations of three TOF and seven normal human fetal hearts. TOF right ventricles (RVs) had smaller end-diastolic volumes (EDVs) but similar stroke volumes (SVs), whereas TOF left ventricles (LVs) had similar EDVs but slightly increased SVs compared with normal ventricles. Simulations showed that TOF ventricles had elevated systolic intraventricular pressure gradient (IVPG) and required additional energy for ejection but IVPG elevations were considered to be mild relative to arterial pressure. TOF RVs and LVs had similar pressures because of equalization via ventricular septal defect (VSD). Furthermore, relative to normal, TOF RVs had increased diastolic wall shear stresses (WSS) but TOF LVs were not. This was caused by high tricuspid inflow that exceeded RV SV, leading to right-to-left shunting and chaotic flow with enhanced vorticity interaction with the wall to elevate WSS. Two of the three TOF RVs but none of the LVs had increased thickness. As pressure elevations were mild, we hypothesized that pressure and WSS elevation could play a role in the RV thickening, among other causative factors. Finally, the endocardium surrounding the VSD consistently experienced high WSS because of RV-to-LV flow shunt and high flow rate through the over-riding aorta. NEW & NOTEWORTHY Blood flow forces are thought to cause congenital heart malformations and influence disease progression. We performed novel investigations of intracardiac fluid mechanics of tetralogy of Fallot (TOF) human fetal hearts and found essential differences from normal hearts. The TOF right ventricle (RV) and left ventricle had similar and elevated pressure but only the TOF RV had elevated wall shear stress because of elevated tricuspid inflow, and this may contribute to the observed RV thickening. TOF hearts also expended more energy for ejection.

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Kim, Youngho, and Sangho Yun. "Fluid Dynamics in an Anatomically Correct Total Cavopulmonary Connection : Flow Visualizations and Computational Fluid Dynamics(Cardiovascular Mechanics)." Proceedings of the Asian Pacific Conference on Biomechanics : emerging science and technology in biomechanics 2004.1 (2004): 57–58. http://dx.doi.org/10.1299/jsmeapbio.2004.1.57.

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Rajesh, Parvati. "Cardiovascular Biofluid Mechanics." International Journal of Innovative Science and Research Technology 5, no. 7 (July 16, 2020): 36–39. http://dx.doi.org/10.38124/ijisrt20jul186.

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This paper intends to study a real-life application of fluid mechanics in cardiovascular blood flow. The study of blood flow is termed as Hemodynamics. Fluid mechanics can be used to analyze the factors and impact of obstruction in blood flow due to fat, cholesterol, and plaque deposits in the coronary arteries of the human heart. These blockages are the grounds for coronary artery diseases and heart attacks. We will look at varying parameters of flowrate and pressure for different thicknesses of epicardial fat as well as define a relationship between these three.

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Nakamura, Masanori, Shigeo Wada, Daisuke Mori, Ken-ichi Tsubota, and Takami Yamaguchi. "Computational Fluid Dynamics Study of the Effect of the Left Ventricular Flow Ejection on the Intraaortic Flow(Cardiovascular Mechanics)." Proceedings of the Asian Pacific Conference on Biomechanics : emerging science and technology in biomechanics 2004.1 (2004): 61–62. http://dx.doi.org/10.1299/jsmeapbio.2004.1.61.

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Marusic, Ivan, and Susan Broomhall. "Leonardo da Vinci and Fluid Mechanics." Annual Review of Fluid Mechanics 53, no. 1 (January 5, 2021): 1–25. http://dx.doi.org/10.1146/annurev-fluid-022620-122816.

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This review focuses on Leonardo da Vinci's work and thought related to fluid mechanics as it is presented in a lifetime of notebooks, letters, and artwork. It shows how Leonardo's remaining works offer a complicated picture of unfinished, scattered, and frequently revisited hypotheses and conclusions. It argues that experimentation formed an important mechanism for Leonardo's thought about natural fluid flows, which was an innovation to the scientific thinking of his day, but which did not always lead him to the conclusions of modern fluid mechanics. It highlights the multiple and ambiguous meanings of turbulence in his works. It examines his thinking suggestive of modern concepts such as the no-slip condition, hydraulic jump, cardiovascular vortices, conservation of volume, and the distinctive path of ascending bubbles we now term Leonardo's paradox, among others. It demonstrates how Leonardo thought through analogies, building-block flow patterns, and synthesis, leading both to successes—especially in the management of water—and to failures, perhaps most obviously in his pursuit of human flight.

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Guala, Andrea, Michele Scalseggi, and Luca Ridolfi. "Coronary fluid mechanics in an ageing cardiovascular system." Meccanica 52, no. 3 (October 5, 2015): 503–14. http://dx.doi.org/10.1007/s11012-015-0283-0.

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Taylor, Charles A., and Mary T. Draney. "EXPERIMENTAL AND COMPUTATIONAL METHODS IN CARDIOVASCULAR FLUID MECHANICS." Annual Review of Fluid Mechanics 36, no. 1 (January 2004): 197–231. http://dx.doi.org/10.1146/annurev.fluid.36.050802.121944.

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Dasi, Lakshmi P., Philippe Sucosky, Diane De Zelicourt, Kartik Sundareswaran, Jorge Jimenez, and Ajit P. Yoganathan. "Advances in Cardiovascular Fluid Mechanics: Bench to Bedside." Annals of the New York Academy of Sciences 1161, no. 1 (April 2009): 1–25. http://dx.doi.org/10.1111/j.1749-6632.2008.04320.x.

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Lee, Sang-Hyun. "NUMERICAL MODELING OF FLUID-STRUCTURE INTERACTIONS IN CARDIOVASCULAR MECHANICS." Journal of Computational Fluids Engineering 22, no. 2 (June 30, 2017): 1–14. http://dx.doi.org/10.6112/kscfe.2017.22.2.001.

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Arzani, Amirhossein, and Shawn C. Shadden. "Wall shear stress fixed points in cardiovascular fluid mechanics." Journal of Biomechanics 73 (May 2018): 145–52. http://dx.doi.org/10.1016/j.jbiomech.2018.03.034.

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Guala*, Andrea, Michele Scalseggi, and Luca Ridolfi. "P5.6 CORONARY FLUID MECHANICS IN AN AGEING CARDIOVASCULAR SYSTEM." Artery Research 12, no. C (2015): 21. http://dx.doi.org/10.1016/j.artres.2015.10.271.

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Courchaine, Katherine, and Sandra Rugonyi. "Quantifying blood flow dynamics during cardiac development: demystifying computational methods." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1759 (September 24, 2018): 20170330. http://dx.doi.org/10.1098/rstb.2017.0330.

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Blood flow conditions (haemodynamics) are crucial for proper cardiovascular development. Indeed, blood flow induces biomechanical adaptations and mechanotransduction signalling that influence cardiovascular growth and development during embryonic stages and beyond. Altered blood flow conditions are a hallmark of congenital heart disease, and disrupted blood flow at early embryonic stages is known to lead to congenital heart malformations. In spite of this, many of the mechanisms by which blood flow mechanics affect cardiovascular development remain unknown. This is due in part to the challenges involved in quantifying blood flow dynamics and the forces exerted by blood flow on developing cardiovascular tissues. Recent technologies, however, have allowed precise measurement of blood flow parameters and cardiovascular geometry even at early embryonic stages. Combined with computational fluid dynamics techniques, it is possible to quantify haemodynamic parameters and their changes over development, which is a crucial step in the quest for understanding the role of mechanical cues on heart and vascular formation. This study summarizes some fundamental aspects of modelling blood flow dynamics, with a focus on three-dimensional modelling techniques, and discusses relevant studies that are revealing the details of blood flow and their influence on cardiovascular development. This article is part of the Theo Murphy meeting issue ‘Mechanics of development’.

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Bracamonte, Johane H., Sarah K. Saunders, John S. Wilson, Uyen T. Truong, and Joao S. Soares. "Patient-Specific Inverse Modeling of In Vivo Cardiovascular Mechanics with Medical Image-Derived Kinematics as Input Data: Concepts, Methods, and Applications." Applied Sciences 12, no. 8 (April 14, 2022): 3954. http://dx.doi.org/10.3390/app12083954.

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Inverse modeling approaches in cardiovascular medicine are a collection of methodologies that can provide non-invasive patient-specific estimations of tissue properties, mechanical loads, and other mechanics-based risk factors using medical imaging as inputs. Its incorporation into clinical practice has the potential to improve diagnosis and treatment planning with low associated risks and costs. These methods have become available for medical applications mainly due to the continuing development of image-based kinematic techniques, the maturity of the associated theories describing cardiovascular function, and recent progress in computer science, modeling, and simulation engineering. Inverse method applications are multidisciplinary, requiring tailored solutions to the available clinical data, pathology of interest, and available computational resources. Herein, we review biomechanical modeling and simulation principles, methods of solving inverse problems, and techniques for image-based kinematic analysis. In the final section, the major advances in inverse modeling of human cardiovascular mechanics since its early development in the early 2000s are reviewed with emphasis on method-specific descriptions, results, and conclusions. We draw selected studies on healthy and diseased hearts, aortas, and pulmonary arteries achieved through the incorporation of tissue mechanics, hemodynamics, and fluid–structure interaction methods paired with patient-specific data acquired with medical imaging in inverse modeling approaches.

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Takizawa, Kenji, Yuri Bazilevs, Tayfun E. Tezduyar, Christopher C. Long, Alison L. Marsden, and Kathleen Schjodt. "ST and ALE-VMS methods for patient-specific cardiovascular fluid mechanics modeling." Mathematical Models and Methods in Applied Sciences 24, no. 12 (August 15, 2014): 2437–86. http://dx.doi.org/10.1142/s0218202514500250.

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This paper provides a review of the space–time (ST) and Arbitrary Lagrangian–Eulerian (ALE) techniques developed by the first three authors' research teams for patient-specific cardiovascular fluid mechanics modeling, including fluid–structure interaction (FSI). The core methods are the ALE-based variational multiscale (ALE-VMS) method, the Deforming-Spatial-Domain/Stabilized ST formulation, and the stabilized ST FSI technique. A good number of special techniques targeting cardiovascular fluid mechanics have been developed to be used with the core methods. These include: (i) arterial-surface extraction and boundary condition techniques, (ii) techniques for using variable arterial wall thickness, (iii) methods for calculating an estimated zero-pressure arterial geometry, (iv) techniques for prestressing of the blood vessel wall, (v) mesh generation techniques for building layers of refined fluid mechanics mesh near the arterial walls, (vi) a special mapping technique for specifying the velocity profile at an inflow boundary with non-circular shape, (vii) a scaling technique for specifying a more realistic volumetric flow rate, (viii) techniques for the projection of fluid–structure interface stresses, (ix) a recipe for pre-FSI computations that improve the convergence of the FSI computations, (x) the Sequentially-Coupled Arterial FSI technique and its multiscale versions, (xi) techniques for calculation of the wall shear stress (WSS) and oscillatory shear index (OSI), (xii) methods for stent modeling and mesh generation, (xiii) methods for calculation of the particle residence time, and (xiv) methods for an estimated element-based zero-stress state for the artery. Here we provide an overview of the special techniques for WSS and OSI calculations, stent modeling and mesh generation, and calculation of the residence time with application to pulsatile ventricular assist device (PVAD). We provide references for some of the other special techniques. With results from earlier computations, we show how these core and special techniques work.

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Sanal Kumar, V. R., Vigneshwaran Sankar, Nichith Chandrasekaran, Vignesh Saravanan, Ajith Sukumaran, Vigneshwaran Rajendran, Shiv Kumar Choudhary, et al. "Universal benchmark data of the three-dimensional boundary layer blockage and average friction coefficient for in silico code verification." Physics of Fluids 34, no. 4 (April 2022): 041301. http://dx.doi.org/10.1063/5.0086638.

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The first law of thermodynamics reveals that all fluids are compressible, and the second law of thermodynamics entails all fluids to have positive viscosity. These established laws reaffirm the possibilities of the occurrence of Sanal flow choking in yocto to yotta scale systems and beyond [Kumar et al., “Discovery of nanoscale Sanal flow choking in cardiovascular system: Exact prediction of the 3D boundary-layer-blockage factor in nanotubes,” Sci. Rep. 11, 15429 (2021); “Sanal flow choking: A paradigm shift in computational fluid dynamics code verification and diagnosing detonation and hemorrhage in real-world fluid-flow systems,” Global Challenges 4, 2000012 (2020)]. The Sanal flow choking occurs in the real-world flows at a critical total-to-static pressure ratio [Kumar et al., “Abstract P422: Sanal flow choking leads to hemorrhagic stroke and other neurological disorders in earth and human spaceflight,” Circul. Res. 129(1), AP422 (2021)]. At the Sanal flow choking condition, the Rayleigh-flow-effect (thermal choking) and the Fanno-flow-effect (choking due to frictional effects) unite at a unique site of the sonic-fluid-throat. In this article, the two-dimensional (2D) and the three-dimensional (3D) boundary-layer-blockage factors and average friction coefficient are generated for different working fluids passing through a cylindrical port, at the Sanal flow choking condition, as universal benchmark data for a credible verification of in silico codes for both adiabatic and diabatic flows. The outlook, advancement, and significance of the analytical methodology, invoked for developing Sanal flow choking model using well-posed initial conditions, for generating the universal benchmark data for computational fluid dynamics code verification are critically reviewed herein. The closed-form analytical models presented herein for predicting the 2D and the 3D boundary-layer-blockage factors at the sonic-fluid-throat of adiabatic and diabatic flows and average friction coefficient in a circular duct at the Sanal flow choking condition are fabulously unaffected with any errors due to discretization and fully freed from empiricism for a credible decision making on various high fidelity numerical simulations. The Sanal flow choking model offers the luxury to the scientific community for solving numerous unresolved problems in boundary layer theory. It provides universal benchmark data for various applications irrespective of the laminar/turbulence flow features in wall-bounded compressible viscous flow systems. The 2D and 3D in silico simulation results are presented for demonstrating conclusively the possibilities of the occurrence of the Sanal flow choking and streamtube flow choking [Kumar et al., “The theoretical prediction of the boundary layer blockage and external flow choking at moving aircraft in ground effects,” Phys. Fluids 33(3), 036108 (2021).] in internal and external flows. The phenomenological manifestation of the flow choking phenomenon reported herein extends disruptive technologies at the cutting-edge to solve century-long unresolved scientific problems in physics of fluids with credibility.

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Hsu, Chuan Fu, Fuh Yu Chang, and Yu Xiang Huang. "Surface Machining of Stainless Steel Cardiovascular Stents by Fluid Abrasive Machining and Electropolishing." Key Engineering Materials 897 (August 17, 2021): 3–13. http://dx.doi.org/10.4028/www.scientific.net/kem.897.3.

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The typical manufacturing process of tubular metallic cardiovascular stents includes laser cutting, sand blasting, acid pickling, electropolishing, surface passivation, and cleaning. The most commonly used material for cardiovascular stents is stainless steel, such as SUS 304 and SUS 316. After the laser cutting process, substantial improvement of the stent surface morphology is required to obtain acceptable surface roughness, edge roundness, and reduction of surface defects. This study focuses on a novel post-treatment method of fluid abrasive machining to replace the conventional sand blasting and acid pickling processes, resulting in the surface smoothness and edge roundness that are suitable for cardiovascular stent fabrication. The dross deposition and striations retained after laser cutting can be significantly removed with fluid abrasive machining. Both DC current and pulse current electropolishing techniques were performed to attain the final surface and structural quality after the fluid abrasive machining process. The experimental results show that an extremely fine surface roughness and a satisfactory edge roundness can be achieved for stents through both DC current and pulse current electropolishing. The pulse electropolishing process is more effective than the DC current electropolishing process to achieve edge roundness with less weight removal.

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Reddy, Narender P., and Sunil K. Kesavan. "Perspectives in Non-Traditional Biofluid Mechanics." Engineering in Medicine 16, no. 1 (January 1987): 43–45. http://dx.doi.org/10.1243/emed_jour_1987_016_010_02.

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Although biofluid mechanics has been studied extensively, most of the studies have concentrated on cardiovascular biofluid mechanics. Very little attention has been paid to the other important problems in biomedicine. Several non-traditional areas which offer interesting and challenging problems remain unexplored, and fluid mechanics can have fruitful interaction with these disciplines. This paper brings into focus some of the important areas of biomedicine which offer fertile grounds for biofluid mechanics studies.

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Rabbitt, R. D. "Semicircular canal biomechanics in health and disease." Journal of Neurophysiology 121, no. 3 (March 1, 2019): 732–55. http://dx.doi.org/10.1152/jn.00708.2018.

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The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity-sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes. Disorders altering canal mechanics result in pathological inputs to the CNS, often leading to debilitating symptoms. Vestibular disorders and conditions with mechanical substrates include benign paroxysmal positional nystagmus, direction-changing positional nystagmus, alcohol positional nystagmus, caloric nystagmus, Tullio phenomena, and others. Here, the mechanics of angular motion transduction and how it contributes to neural encoding by the semicircular canals is reviewed in both health and disease.

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Kamensky, David, Ming-Chen Hsu, Yue Yu, John A. Evans, Michael S. Sacks, and Thomas J. R. Hughes. "Immersogeometric cardiovascular fluid–structure interaction analysis with divergence-conforming B-splines." Computer Methods in Applied Mechanics and Engineering 314 (February 2017): 408–72. http://dx.doi.org/10.1016/j.cma.2016.07.028.

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Alberto Figueroa, C., Seungik Baek, Charles A. Taylor, and Jay D. Humphrey. "A computational framework for fluid–solid-growth modeling in cardiovascular simulations." Computer Methods in Applied Mechanics and Engineering 198, no. 45-46 (September 2009): 3583–602. http://dx.doi.org/10.1016/j.cma.2008.09.013.

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Terahara, Takuya, Kenji Takizawa, Tayfun E. Tezduyar, Yuri Bazilevs, and Ming-Chen Hsu. "Heart valve isogeometric sequentially-coupled FSI analysis with the space–time topology change method." Computational Mechanics 65, no. 4 (January 10, 2020): 1167–87. http://dx.doi.org/10.1007/s00466-019-01813-0.

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AbstractHeart valve fluid–structure interaction (FSI) analysis is one of the computationally challenging cases in cardiovascular fluid mechanics. The challenges include unsteady flow through a complex geometry, solid surfaces with large motion, and contact between the valve leaflets. We introduce here an isogeometric sequentially-coupled FSI (SCFSI) method that can address the challenges with an outcome of high-fidelity flow solutions. The SCFSI analysis enables dealing with the fluid and structure parts individually at different steps of the solutions sequence, and also enables using different methods or different mesh resolution levels at different steps. In the isogeometric SCFSI analysis here, the first step is a previously computed (fully) coupled Immersogeometric Analysis FSI of the heart valve with a reasonable flow solution. With the valve leaflet and arterial surface motion coming from that, we perform a new, higher-fidelity fluid mechanics computation with the space–time topology change method and isogeometric discretization. Both the immersogeometric and space–time methods are variational multiscale methods. The computation presented for a bioprosthetic heart valve demonstrates the power of the method introduced.

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Takizawa, Kenji, Yuri Bazilevs, Tayfun E. Tezduyar, Ming-Chen Hsu, and Takuya Terahara. "Computational Cardiovascular Medicine With Isogeometric Analysis." Journal of Advanced Engineering and Computation 6, no. 3 (September 30, 2022): 167. http://dx.doi.org/10.55579/jaec.202263.381.

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Isogeometric analysis (IGA) brought superior accuracy to computations in both fluid and solid mechanics. The increased accuracy has been in representing both the problem geometry and the variables computed. Beyond using IGA basis functions in space, with IGA basis functions in time in a space–time (ST) context, we can have increased accuracy also in representing the motion of solid surfaces. Around the core methods such as the residual-based variational multiscale (VMS), ST-VMS and arbitrary Lagrangian–Eulerian VMS methods, with complex-geometry IGA mesh generation methods and immersogeometric analysis, and with special methods targeting specific classes of computations, the IGA has been very effective in computational cardiovascular medicine. We provide an overview of these IGA-based computational cardiovascular-medicine methods and present examples of the computations performed.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

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Winkler, Christina Maria, Antonia Isabel Kuhn, Gesine Hentschel, and Birgit Glasmacher. "A Review on Novel Channel Materials for Particle Image Velocimetry Measurements—Usability of Hydrogels in Cardiovascular Applications." Gels 8, no. 8 (August 12, 2022): 502. http://dx.doi.org/10.3390/gels8080502.

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Particle image velocimetry (PIV) is an optical and contactless measurement method for analyzing fluid blood dynamics in cardiovascular research. The main challenge to visualization investigated in the current research was matching the channel material’s index of refraction (IOR) to that of the fluid. Silicone is typically used as a channel material for these applications, so optical matching cannot be proven. This review considers hydrogel as a new PIV channel material for IOR matching. The advantages of hydrogels are their optical and mechanical properties. Hydrogels swell more than 90 vol% when hydrated in an aqueous solution and have an elastic behavior. This paper aimed to review single, double, and triple networks and nanocomposite hydrogels with suitable optical and mechanical properties to be used as PIV channel material, with a focus on cardiovascular applications. The properties are summarized in seven hydrogel groups: PAMPS, PAA, PVA, PAAm, PEG and PEO, PSA, and PNIPA. The reliability of the optical properties is related to low IORs, which allow higher light transmission. On the other hand, elastic modulus, tensile/compressive stress, and nominal tensile/compressive strain are higher for multiple-cross-linked and nanocomposite hydrogels than single mono-cross-linked gels. This review describes methods for measuring optical and mechanical properties, e.g., refractometry and mechanical testing.

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Yavelov, I. S., G. L. Danielyan, A. V. Rochagov, and A. V. Zholobov. "Evolution of the cardiac analyzer “Pulse” and the mobile medical devices." CARDIOMETRY, no. 23 (August 20, 2022): 46–50. http://dx.doi.org/10.18137/cardiometry.2022.23.4650.

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The basis of one of the areas in biomechanics, associated with the development of hemodynamics and fluid mechanics of the heart muscle, has been the use of new fiber-optic sensors, previously developed to solve some engineering problems. In particular, the original sensors of pressure and other physical quantities have been modified for the purpose of measuring cardiac mechanical signals, namely tones, noises and other vibration signals of the heart and pulse pressure waves in the circulatory system. The main idea of introducing such sensors into medicine is formulated as an attempt to enable a general practitioner or a cardiologist, as well as any expert, to quickly collect the necessary data both on the patient’s state of the cardiovascular system and the condition of the entire organism in general. In parallel with designing the sensors, secondary equipment and signal processing algorithms have been developed.

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Ebbers, T., L. Wigstro¨m, A. F. Bolger, B. Wranne, and M. Karlsson. "Noninvasive Measurement of Time-Varying Three-Dimensional Relative Pressure Fields Within the Human Heart." Journal of Biomechanical Engineering 124, no. 3 (May 21, 2002): 288–93. http://dx.doi.org/10.1115/1.1468866.

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Understanding cardiac blood flow patterns is important in the assessment of cardiovascular function. Three-dimensional flow and relative pressure fields within the human left ventricle are demonstrated by combining velocity measurements with computational fluid mechanics methods. The velocity field throughout the left atrium and ventricle of a normal human heart is measured using time-resolved three-dimensional phase-contrast MRI. Subsequently, the time-resolved three-dimensional relative pressure is calculated from this velocity field using the pressure Poisson equation. Noninvasive simultaneous assessment of cardiac pressure and flow phenomena is an important new tool for studying cardiac fluid dynamics.

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Pekkan, Kerem, and John N. Oshinski. "Shaping the field of Cardiovascular Fluid Mechanics: The 40th Anniversary of Ajit Yoganathan’s Research Laboratory." Cardiovascular Engineering and Technology 12, no. 6 (October 8, 2021): 557–58. http://dx.doi.org/10.1007/s13239-021-00576-1.

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Sanal Kumar, V. R., Bharath Rajaghatta Sundararam, Pradeep Kumar Radhakrishnan, Nichith Chandrasekaran, Shiv Kumar Choudhary, Vigneshwaran Sankar, Ajith Sukumaran, et al. "In vitro prediction of the lower/upper-critical biofluid flow choking index and in vivo demonstration of flow choking in the stenosis artery of the animal with air embolism." Physics of Fluids 34, no. 10 (October 2022): 101302. http://dx.doi.org/10.1063/5.0105407.

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Diagnostic investigations of aneurysm, hemorrhagic stroke, and other asymptomatic cardiovascular diseases and neurological disorders due to the flow choking (biofluid/boundary layer blockage persuaded flow choking) phenomenon in the circulatory system of humans and animals on the Earth and in the human spaceflight are active research topics of topical interest {Kumar et al., “boundary layer blockage persuaded flow choking leads to hemorrhagic stroke and other neurological disorders in earth and human spaceflight,” Paper presented at the Basic Cardiovascular Sciences Conference, 23–25 August 2021 (American Stroke Association, 2021) [Circ. Res. 129, AP422 (2021)] and “Lopsided blood-thinning drug increases the risk of internal flow choking and shock wave generation causing asymptomatic stroke,” in International Stroke Conference, 19–20 March 2021 (American Stroke Association, 2021) [Stroke 52, AP804 (2021)]}. The theoretical concept of flow choking [Kumar et al., “Lopsided blood-thinning drug increases the risk of internal flow choking leading to shock wave generation causing asymptomatic cardiovascular disease,” Global Challenges 5, 2000076 (2021); “Discovery of nanoscale boundary layer blockage persuaded flow choking in cardiovascular system—Exact prediction of the 3D boundary-layer-blockage factor in nanotubes,” Sci. Rep. 11, 15429 (2021); and “The theoretical prediction of the boundary layer blockage and external flow choking at moving aircraft in ground effects,” Phys. Fluids 33(3), 036108 (2021)] in the cardiovascular system (CVS) due to gas embolism is established herein through analytical, in vitro (Kumar et al., “Nanoscale flow choking and spaceflight effects on cardiovascular risk of astronauts—A new perspective,” AIAA Paper No. 2021-0357, 2021), in silico (Kumar et al., “Boundary layer blockage, Venturi effect and cavitation causing aerodynamic choking and shock waves in human artery leading to hemorrhage and massive heart attack—A new perspective,” AIAA Paper No. 2018-3962, 2018), and in vivo animal methodology [Jayaraman et al., “Animal in vivo: The proof of flow choking and bulging of the downstream region of the stenosis artery due to air embolism,” Paper presented at the Basic Cardiovascular Sciences Conference , 25–28 July 2022 (American Heart Association, 2022)]. The boundary layer blockage persuaded flow choking phenomenon is a compressible viscous flow effect, and it arises at a critical pressure ratio in continuum/non-continuum real-world yocto to yotta scale flow systems and beyond [Kumar et al., “Universal benchmark data of the three-dimensional boundary layer blockage and average friction coefficient for in silico code verification,” Phys. Fluids 34(4), 041301 (2022)]. The closed-form analytical models, capable of predicting the flow choking in CVS, developed from the well-established compressible viscous flow theory are reviewed and presented herein. The lower-critical flow-choking index of the healthy subject (human being/animal) is predicted through the speciation analysis of blood. The upper-critical flow-choking index is predicted from the specific heat of blood at constant pressure (Cp) and constant volume (Cv), estimated using the Differential Scanning Calorimeter. These flow-choking indexes, highlighted in terms of systolic-to-diastolic blood pressure ratio (SBP/DBP), are exclusively controlled by the biofluid/blood heat capacity ratio (BHCR = Cp/Cv). An in vitro study shows that nitrogen (N2), oxygen (O2), and carbon dioxide (CO2) gases are predominant in fresh-blood samples of the healthy humans and Guinea pigs at a temperature range of 37–40 °C (98.6–104 °F) causing gas embolism. In silico results demonstrated the existence of the biofluid/boundary layer blockage persuaded flow choking, stream tube flow choking, shock wave generation, and pressure overshoot in the downstream region of simulated arteries (with and without stenosis), at a critical pressure ratio, due to gas embolism. The flow choking followed by aneurysm (i.e., bulging of the downstream region of the stenosis artery due to shock wave generation) due to air embolism is demonstrated through small animal in vivo studies. We could corroborate herein, with the animal in vivo and three-dimensional in silico studies, that flow-choking followed by shock wave generation and pressure overshoot occurs in arteries with stenosis due to air embolism at a critical pressure ratio. Analytical models reveal that flow-choking occurs at relatively high and low blood viscosities in CVS at a critical blood pressure ratio (BPR), which leads to memory effect (stroke history/arterial stiffness) and asymptomatic cardiovascular diseases [Kumar et al., “Lopsided blood-thinning drug increases the risk of internal flow choking leading to shock wave generation causing asymptomatic cardiovascular disease,” Global Challenges 5, 2000076 (2021)]. We concluded that an overdose of drug for reducing the blood viscosity enhances the risk of flow choking (biofluid/boundary layer blockage persuaded flow choking) due to an enhanced boundary layer blockage (BLB) factor because of the rise in Reynolds number ( Re) and turbulence. An analytical model establishes that an increase in Re due to the individual or the joint effects of fluid density, fluid viscosity, fluid velocity, and the hydraulic diameter of the vessel creates high turbulence level in CVS instigating an escalated BLB factor heading to a rapid adverse flow choking. Therefore, prescribing the exact blood-thinning course of therapy is crucial for achieving the anticipated curative value and further annulling adverse flow choking (biofluid/boundary layer blockage persuaded flow choking) in CVS. We could conclude authoritatively herein, with the animal in vivo studies, that flow choking occurs in the artery with stenosis due to air embolism at a critical BPR (i.e., SBP/DBP = 1.892 9), which is regulated by the heat capacity ratio of air. The cardiovascular risk due to boundary layer blockage persuaded flow choking could be diminished by concurrently reducing the viscosity of biofluid/blood and flow-turbulence. This comprehensive review is a pointer toward achieving relentless unchoked flow conditions (i.e., flow Mach number < 1) in the CVS for prohibiting asymptomatic cardiovascular diseases and neurological disorders associated with flow choking and shock wave generation followed by pressure overshoot causing arterial stiffness. The unchoked flow condition can be achieved in every subject (human/animal) by suitably increasing the thermal-tolerance-level in terms of BHCR and/or by reducing the BPR within the pathophysiological range of individual subjects through the new drug discovery, the new companion drug with the conventional blood thinners and/or proper health care management for increasing the healthy-life span of one and all in the universe.

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Wiputra, Hadi, Chang Quan Lai, Guat Ling Lim, Joel Jia Wei Heng, Lan Guo, Sanah Merchant Soomar, Hwa Liang Leo, Arijit Biwas, Citra Nurfarah Zaini Mattar, and Choon Hwai Yap. "Fluid mechanics of human fetal right ventricles from image-based computational fluid dynamics using 4D clinical ultrasound scans." American Journal of Physiology-Heart and Circulatory Physiology 311, no. 6 (December 1, 2016): H1498—H1508. http://dx.doi.org/10.1152/ajpheart.00400.2016.

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There are 0.6–1.9% of US children who were born with congenital heart malformations. Clinical and animal studies suggest that abnormal blood flow forces might play a role in causing these malformation, highlighting the importance of understanding the fetal cardiovascular fluid mechanics. We performed computational fluid dynamics simulations of the right ventricles, based on four-dimensional ultrasound scans of three 20-wk-old normal human fetuses, to characterize their flow and energy dynamics. Peak intraventricular pressure gradients were found to be 0.2–0.9 mmHg during systole, and 0.1–0.2 mmHg during diastole. Diastolic wall shear stresses were found to be around 1 Pa, which could elevate to 2–4 Pa during systole in the outflow tract. Fetal right ventricles have complex flow patterns featuring two interacting diastolic vortex rings, formed during diastolic E wave and A wave. These rings persisted through the end of systole and elevated wall shear stresses in their proximity. They were observed to conserve ∼25.0% of peak diastolic kinetic energy to be carried over into the subsequent systole. However, this carried-over kinetic energy did not significantly alter the work done by the heart for ejection. Thus, while diastolic vortexes played a significant role in determining spatial patterns and magnitudes of diastolic wall shear stresses, they did not have significant influence on systolic ejection. Our results can serve as a baseline for future comparison with diseased hearts.

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Nucifora, Gaetano, Victoria Delgado, Matteo Bertini, Nina Ajmone Marsan, Nico R. Van de Veire, Arnold C. T. Ng, Hans-Marc J. Siebelink, et al. "Left Ventricular Muscle and Fluid Mechanics in Acute Myocardial Infarction." American Journal of Cardiology 106, no. 10 (November 2010): 1404–9. http://dx.doi.org/10.1016/j.amjcard.2010.06.072.

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Bihari, Shailesh, Ubbo F. Wiersema, David Schembri, Carmine G. De Pasquale, Dani-Louise Dixon, Shivesh Prakash, Mark D. Lawrence, Jeffrey J. Bowden, and Andrew D. Bersten. "Bolus intravenous 0.9% saline, but not 4% albumin or 5% glucose, causes interstitial pulmonary edema in healthy subjects." Journal of Applied Physiology 119, no. 7 (October 1, 2015): 783–92. http://dx.doi.org/10.1152/japplphysiol.00356.2015.

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Rapid intravenous (iv) infusion of 0.9% saline alters respiratory mechanics in healthy subjects. However, the relative cardiovascular and respiratory effects of bolus iv crystalloid vs. colloid are unknown. Six healthy male volunteers were given 30 ml/kg iv 0.9% saline, 4% albumin, and 5% glucose at a rate of 100 ml/min on 3 separate days in a double-blinded, randomized crossover study. Impulse oscillometry, spirometry, lung volumes, diffusing capacity (DLCO), and blood samples were measured before and after fluid administration. Lung ultrasound B-line score (indicating interstitial pulmonary edema) and Doppler echocardiography indices of cardiac preload were measured before, midway, immediately after, and 1 h after fluid administration. Infusion of 0.9% saline increased small airway resistance at 5 Hz ( P = 0.04) and lung ultrasound B-line score ( P = 0.01) without changes in Doppler echocardiography measures of preload. In contrast, 4% albumin increased DLCO, decreased lung volumes, and increased the Doppler echocardiography mitral E velocity ( P = 0.001) and E-to-lateral/septal e′ ratio, estimated blood volume, and N-terminal pro B-type natriuretic peptide ( P = 0.01) but not lung ultrasound B-line score, consistent with increased pulmonary blood volume without interstitial pulmonary edema. There were no significant changes with 5% glucose. Plasma angiopoietin-2 concentration increased only after 0.9% saline ( P = 0.001), suggesting an inflammatory mechanism associated with edema formation. In healthy subjects, 0.9% saline and 4% albumin have differential pulmonary effects not attributable to passive fluid filtration. This may reflect either different effects of these fluids on active signaling in the pulmonary circulation or a protective effect of albumin.

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Petersen, Lonnie G., Alan Hargens, Elizabeth M. Bird, Neeki Ashari, Jordan Saalfeld, and Johan C. G. Petersen. "Mobile Lower Body Negative Pressure Suit as an Integrative Countermeasure for Spaceflight." Aerospace Medicine and Human Performance 90, no. 12 (December 1, 2019): 993–99. http://dx.doi.org/10.3357/amhp.5408.2019.

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BACKGROUND: Persistent headward fluid shift and mechanical unloading cause neuro-ocular, cardiovascular, and musculoskeletal deconditioning during long-term spaceflight. Lower body negative pressure (LBNP) reintroduces footward fluid shift and mechanical loading.METHODS: We designed, built, and tested a wearable, mobile, and flexible LBNP device (GravitySuit) consisting of pressurized trousers with built-in shoes to support ground reaction forces (GRF) and a thoracic vest to distribute load to the entire axial length of the body. In eight healthy subjects we recorded GRF under the feet and over the shoulders (Tekscan) while assessing cardiovascular response (Nexfin) and footward fluid shift from internal jugular venous cross-sectional area (IJVa) using ultrasound (Terason).RESULTS: Relative to normal bodyweight (BW) when standing upright, increments of 10 mmHg LBNP from 0 to 40 mmHg while supine induced axial loading corresponding to 0%, 13 ± 3%, 41 ± 5%, 75 ± 11%, and 125 ± 22% BW, respectively. Furthermore, LBNP reduced IJVa from 1.12 ± 0.3 cm2 to 0.67 ± 0.2, 0.50 ± 0.1, 0.35 ± 0.1, and 0.31 ± 0.1 cm2, respectively. LBNP of 30 and 40 mmHg reduced cardiac stroke volume and increased heart rate while cardiac output and mean arterial pressure were unaffected. During 2 h of supine rest at 20 mmHg LBNP, temperature and humidity inside the suit were unchanged (23 ± 1°C; 47 ± 3%, respectively).DISCUSSION: The flexible GravitySuit at 20 mmHg LBNP comfortably induced mechanical loading and desired fluid displacement while maintaining the mobility of hips and knee joints. The GravitySuit may provide a feasible method to apply low-level, long-term LBNP without interfering with daily activity during spaceflight to provide an integrative countermeasure.Petersen LG, Hargens A, Bird EM, Ashari N, Saalfeld J, Petersen JCG. Mobile lower body negative pressure suit as an integrative countermeasure for spaceflight. Aerosp Med Hum Perform. 2019; 90(12):993–999.

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Kadem, Lyes, and Damien Garcia. "Are We Using the Right Fluid Mechanics Principles?" Annals of Thoracic Surgery 83, no. 1 (January 2007): 354. http://dx.doi.org/10.1016/j.athoracsur.2006.04.009.

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Han, Cong Zhen, Jing An Li, Dan Zou, Xiao Luo, Ping Yang, An Sha Zhao, and Nan Huang. "Mechanical Property of TiO₂ Micro/Nano Surface Based on the Investigation of Residual Stress, Tensile Force and Fluid Flow Shear Stress: For Potential Application of Cardiovascular Devices." Journal of Nano Research 49 (September 2017): 190–201. http://dx.doi.org/10.4028/www.scientific.net/jnanor.49.190.

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The micro-patterned TiO2 nanotube has been anticipated for potential application for cardiovascular implanted devices for its excellent drug loading/ release function and biocompatibility. However, its mechanical behavior has rarely been studied as the cardiovascular devices. The tube length is a crucial factor which not only decides the drug loading ability but also influences the devices’ mechanical behavior. Therefore, in this work, the micro-patterned TiO2 nanotubes with different tube length (MNT2, MNT4 and MNT6) were fabricated, and their surface energy, residual stress, tensile tolerability and blood flow shear stress tolerability were determined, respectively. The results showed that the microstructure reduced the surface energy of the nanotubes surfaces, enhanced or reduced surface tensile tolerability when parallel or vertical to the strain orientation, and also increased the nanotubes surfaces residual stress; In addition, both micro/nano and single nano surfaces possessed good blood flow shear stress tolerability. These results indicated that the micro/nano surfaces possesses excellent mechanical properties for surface modification of cardiovascular devices.

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Rigatelli, Gianluca, Marco Zuin, Sarthak Agarwal, Vivian Nguyen, Cardy Nguyen, Sanyaa Agarwal, and Thach Nguyen. "Applications of Computational Fluid Dynamics in Cardiovascular Disease." TTU Journal of Biomedical Sciences 1, no. 1 (2022): 12–20. http://dx.doi.org/10.53901/tjbs.2022.10.art02.

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Computational fluid dynamics (CFD), alone or coupled with the most advanced imaging tools, allows for the assessment of blood flow patterns in cardiovascular disease to both understand their pathophysiology and anticipate the results of their surgical or interventional repair. CFD is a mathematical technique that characterizes fluid flow using the laws of physics. Through the utilization of specific software and numerical procedures based on virtual simulation and/or patient data from computed tomography, resonance imaging, and 3D/4D ultrasound, models of circulation for most CHDs can be reconstructed. CFD can provide insight into the pathophysiology of coronary artery anomalies, interatrial shunts, coarctation of the aorta and bicuspid aortic valve, tetralogy of Fallot and univentricular heart, valvular heart disease, and aortic disease. In some cases, CFD may be able to simulate different types of surgical or interventional repairs, allowing for the tailoring of treatment accordingly.

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Torii, Ryo, Marie Oshima, Toshio Kobayashi, Kiyoshi Takagi, and Tayfun E. Tezduyar. "Computer modeling of cardiovascular fluid–structure interactions with the deforming-spatial-domain/stabilized space–time formulation." Computer Methods in Applied Mechanics and Engineering 195, no. 13-16 (February 2006): 1885–95. http://dx.doi.org/10.1016/j.cma.2005.05.050.

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Ikomi, F., and G. W. Schmid-Schonbein. "Lymph pump mechanics in the rabbit hind leg." American Journal of Physiology-Heart and Circulatory Physiology 271, no. 1 (July 1, 1996): H173—H183. http://dx.doi.org/10.1152/ajpheart.1996.271.1.h173.

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The mechanisms that govern fluid uptake by the initial lymphatics and adjustment of lymph flow rates remain to a large degree uncertain. The aim of this study was to examine how passive tissue movement contributes to lymph flow rates. Lymph fluid was collected via a cannula inserted into one of the popliteal prenodal lymphatics in the rabbit hind leg. Lymph flow rates were measured during periodic whole leg rotation and controlled oscillatory massage of the dorsal skin of the foot. Without whole leg rotation, lymph flow remained at low values (< 0.01 ml/h). Introduction of whole leg passive rotation caused a frequency-dependent increase in lymph flow rates, which were increased linearly with the log of frequency between 0.03 and 1.0 Hz. Local skin massage in the region of the initial lymphatics also led to a similar increase of lymph flow rates dependent on frequency as well as amplitude of skin displacement. Lymph flow rates during local skin massage reached a comparable order of magnitude regardless of whether the animal was alive or the heart had been arrested, suggesting that local lymph flow rates can be adjusted by periodic tissue motion independently of capillary fluid filtration pressures. The results indicate that periodic expansion and compression of initial lymphatics provide a mechanism for lymph pumping.

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DAHL, KRIS NOEL, AGNIESZKA KALINOWSKI, and KEREM PEKKAN. "Mechanobiology and the Microcirculation: Cellular, Nuclear and Fluid Mechanics." Microcirculation 17, no. 3 (April 2010): 179–91. http://dx.doi.org/10.1111/j.1549-8719.2009.00016.x.

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Sun, Lei, Lijie Ding, Lei Li, Ningning Yin, Nianen Yang, Yi Zhang, Xiaodong Xing, Zhiyong Zhang, and Chen Dong. "Hemodynamic Characteristics of Cardiovascular System in Simulated Zero and Partial Gravities Based on CFD Modeling and Simulation." Life 13, no. 2 (February 1, 2023): 407. http://dx.doi.org/10.3390/life13020407.

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Zero and partial gravities (ZPG) increase cardiovascular risk, while the corresponding theoretical foundation remains uncertain. In the article, the ZPG were generated through a rotating frame with two degrees of freedom in combination with the random walk algorithm. A precise 3D geometric configuration of the cardiovascular system was developed, and the Navier-Stokes laminar flow and solid mechanics were used as governing equations for blood flow and the surrounding tissue in the cardiovascular system. The ZPG were designed into governing equations through the volume force term. The computational fluid dynamics’ (CFD) simulations in combination with proper boundary conditions were carried out to investigate the influences of ZPG on the distribution of blood flow velocity, pressure, and shear stress in the cardiovascular system. The findings show that as simulated gravity gradually decreases from 0.7 g to 0.5 g to 0.3 g to 0 g, as opposed to normal gravity of 1 g, the maximum values of blood flow velocity, pressure, and shear stress on the walls of the aorta and its ramification significantly increase, which would lead to cardiovascular diseases. The research will lay a theoretical foundation for the comprehension of the ZPG effect on cardiovascular risk and the development of effective prevention and control measures under the circumstance of ZPG.

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Taft, Kimberly J., Alfred H. Stammers, Clinton C. Jones, Melinda S. Dickes, Michelle L. Pierce, and Daniel J. Beck. "Cardioplegia flow dynamics in an in vitro model." Perfusion 14, no. 5 (September 1999): 341–49. http://dx.doi.org/10.1177/026765919901400505.

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The flow of fluids in extracorporeal circuits does not conform to conventional Poiseuille mechanics which confounds calculating cardioplegia (CP) flow distribution. The purpose of this study was to quantify CP flow dynamics in a model simulating coronary atherosclerosis across varying sized restrictions. An in vitro preparation was designed to assess hydraulic fluid movement across paired restrictions of 51, 81 and 98% lumen reductions. Volume data were obtained at variable flow, temperature, viscosity and pressure conditions. CP delivered through 14- and 18-gauge (GA) conduits at 8°C and 100 mmHg infusion pressure revealed that both four to one and crystalloid CP solutions had significantly less total percentage flow through the 14-GA conduit, p < 0.0001 and p < 0.001, respectively. Overall, 4:1 CP exhibited the most favorable fluid dynamics at 8°C in that it delivered the highest percentages of total CP flow through the smaller lumen conduit. At both 8°C and 37°C delivery, blood CP resulted in the least homogeneous fluid distribution at all delivery parameters. The results in relation to blood viscosity indicate that, although the 8°C blood CP had a significantly greater viscosity than 37°C blood CP, it did not produce an effect in fluid distribution. These data show that increasing the cardioplegic solution hematocrit causes an inhomogeneous fluid distribution regardless of delivery temperature or infusion pressure.

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Hierck, Beerend P., Kim Van der Heiden, Christian Poelma, Jerry Westerweel, and Robert E. Poelmann. "Fluid Shear Stress and Inner Curvature Remodeling of the Embryonic Heart. Choosing the Right Lane!" Scientific World JOURNAL 8 (2008): 212–22. http://dx.doi.org/10.1100/tsw.2008.42.

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Cardiovascular development is directed or modulated by genetic and epigenetic factors. The latter include blood flow-related shear stress and blood pressure-related circumferential strain. This review focuses on shear stress and its effects on endothelial cells lining the inner surfaces of the heart and blood vessels. Flow characteristics of the embryonic blood, like velocity, viscosity and periodicity, are taken into account to describe the responses of endothelial cells to shear stress and the sensors for this friction force. The primary cilium, which is an integral part of the shear sensor, connects to the cytoskeletal microtubules and transmits information about the level and direction of blood flow into the endothelial cell. When the heart remodels from a more or less straight into a c-shaped tube the sharp curvature, in combination with the small vessel dimensions and high relative viscosity, directs the highest shear stress to the inner curvature of this pump. This proves to be an important epigenetic modulator of cardiac morphogenesis because when shear stress is experimentally altered inner curvature remodeling is affected which leads to the development of congenital cardiovascular anomalies. The best of both worlds, mechanics and biology, are used here to describe early cardiogenesis.

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Kohli, Keshav, Zhenglun Alan Wei, Vahid Sadri, Thomas Easley, Eric Pierce, John Oshinski, Dee Dee Wang, et al. "TCT-19 Predicting TMVR-Related LVOT Obstruction: Concept of Fluid Mechanics Modeling." Journal of the American College of Cardiology 72, no. 13 (September 2018): B8—B9. http://dx.doi.org/10.1016/j.jacc.2018.08.1097.

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Omori, T., T. Ishikawa, Y. Imai, and T. Yamaguchi. "Shear-induced diffusion of red blood cells in a semi-dilute suspension." Journal of Fluid Mechanics 724 (April 29, 2013): 154–74. http://dx.doi.org/10.1017/jfm.2013.159.

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AbstractThe diffusion of red blood cells (RBCs) in blood is important to the physiology and pathology of the cardiovascular system. In this study, we investigate flow-induced diffusion of RBCs in a semi-dilute system by calculating the pairwise interactions between RBCs in simple shear flow. A capsule with a hyperelastic membrane was used to model an RBC. Its deformation was resolved using the finite element method, whereas fluid motion inside and outside the RBC was solved using the boundary element method. The results show that shear-induced RBC diffusion is significantly anisotropic, i.e. the velocity gradient direction component is larger than the vorticity direction. We also found that the motion of RBCs during the interaction is strongly dependent on the viscosity ratio of the internal to external fluid, and the diffusivity decreases monotonically as the viscosity ratio increases. The scaling argument also suggests that the diffusivity is proportional to the shear rate and haematocrit, if the suspension is in a semi-dilute environment and the capillary number is invariant. These fundamental findings are useful to understand transport phenomena in blood flow.

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SEN, S., and S. CHAKRAVARTY. "A NONLINEAR UNSTEADY RESPONSE OF NON-NEWTONIAN BLOOD FLOW PAST AN OVERLAPPING ARTERIAL CONSTRICTION." Journal of Mechanics in Medicine and Biology 07, no. 04 (December 2007): 463–89. http://dx.doi.org/10.1142/s0219519407002352.

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The present study deals with an appropriate mathematical model describing blood flow through a constricted artery that is used to analyze the physiological flow field. The time-variant geometry of the arterial segment having an overlapping type of constriction in the arterial lumen — which frequently occurs in diseased arteries, causing flow disorder and leading to malfunction of the cardiovascular system — is framed mathematically. Blood flow contained in the stenosed artery is treated as non-Newtonian (having shear-dependent viscosity) and is considered to be two-dimensional. The motion of the arterial wall and its effect on local fluid mechanics are not ruled out from the present pursuit. The flow analysis applies the time-dependent, two-dimensional incompressible nonlinear Navier–Stokes equations for non-Newtonian fluids. The flow field can be obtained by first transforming radial coordinates with the use of appropriate boundary conditions, and then adopting a suitable finite difference scheme numerically. The unsteady response of the system and the influence of the arterial wall distensibility, the non-Newtonian rheology of blood, and the presence of stenosis on the important aspects of the physiological flow phenomena are quantified in order to indicate the susceptibility to atherosclerotic lesions and thereby validate the applicability of the present theoretical model.

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Rudenko, M. Y., V. A. Zernov, O. K. Voronova, E. Y. Bersenev, and I. A. Bersenev. "Genome expression induced by specific low-intensity EMF as an effective method for increasing immunity." CARDIOMETRY, no. 18 (May 18, 2021): 19–23. http://dx.doi.org/10.18137/cardiometry.2021.18.1823.

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For the purpose of research of the cardiovascular system performance, various electromagnetic phenomena are widely considered. In particular, an ECG is treated as a result from the electrical activity by the myocardial cells. As to our research team, at the first stage of creating the cardiometric theory, we have focused on hemodynamics: our attention has been occupied in developing a fresh model of the human blood flow from the point of view of fluid mechanics [1]. Our mathematical concept of the cardiac cycle phase structure, which determines the cardiovascular system performance, has allowed achieving very good results in diagnostics. We have succeeded in making a number of scientific discoveries which have become the basis for a new science: cardiometry. But our experience has demanded to make further important steps in research, and we have concentrated our efforts on developing new methods oftherapy to effectively solve the problems revealed by cardiometry.

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Jones, E. A. V., M. H. Baron, S. E. Fraser, and M. E. Dickinson. "Measuring hemodynamic changes during mammalian development." American Journal of Physiology-Heart and Circulatory Physiology 287, no. 4 (October 2004): H1561—H1569. http://dx.doi.org/10.1152/ajpheart.00081.2004.

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The pathogenesis of many congenital cardiovascular diseases involves abnormal flow within the embryonic vasculature that results either from malformations of the heart or defects in the vasculature itself. Extensive genetic and genomic analysis in mice has led to the identification of an array of mutations that result in cardiovascular defects during embryogenesis. Many of these mutations cause secondary effects within the vasculature that are thought to arise because of altered fluid dynamics. Presumably, cardiac defects disturb or reduce flow and thereby lead to the disruption of the mechanical signals necessary for proper vascular development. Unfortunately, a precise understanding of how flow disruptions lead to secondary vasculature defects has been hampered by the inadequacy of existing analytical tools. Here, we used a fast line-scanning technique for the quantitative analysis of hemodynamics during early organogenesis in mouse embryos, and we present a model system for studying cellular responses during the formation and remodeling of the mammalian cardiovascular system. Flow velocity profiles can be measured as soon as a heart begins to beat even in newly formed vessels. These studies establish a link between the pattern of blood flow within the vasculature and the stage of heart development and also enable analysis of the influence of mechanical forces during development.

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Schwarz, Erica L., Luca Pegolotti, Martin R. Pfaller, and Alison L. Marsden. "Beyond CFD: Emerging methodologies for predictive simulation in cardiovascular health and disease." Biophysics Reviews 4, no. 1 (March 2023): 011301. http://dx.doi.org/10.1063/5.0109400.

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Physics-based computational models of the cardiovascular system are increasingly used to simulate hemodynamics, tissue mechanics, and physiology in evolving healthy and diseased states. While predictive models using computational fluid dynamics (CFD) originated primarily for use in surgical planning, their application now extends well beyond this purpose. In this review, we describe an increasingly wide range of modeling applications aimed at uncovering fundamental mechanisms of disease progression and development, performing model-guided design, and generating testable hypotheses to drive targeted experiments. Increasingly, models are incorporating multiple physical processes spanning a wide range of time and length scales in the heart and vasculature. With these expanded capabilities, clinical adoption of patient-specific modeling in congenital and acquired cardiovascular disease is also increasing, impacting clinical care and treatment decisions in complex congenital heart disease, coronary artery disease, vascular surgery, pulmonary artery disease, and medical device design. In support of these efforts, we discuss recent advances in modeling methodology, which are most impactful when driven by clinical needs. We describe pivotal recent developments in image processing, fluid–structure interaction, modeling under uncertainty, and reduced order modeling to enable simulations in clinically relevant timeframes. In all these areas, we argue that traditional CFD alone is insufficient to tackle increasingly complex clinical and biological problems across scales and systems. Rather, CFD should be coupled with appropriate multiscale biological, physical, and physiological models needed to produce comprehensive, impactful models of mechanobiological systems and complex clinical scenarios. With this perspective, we finally outline open problems and future challenges in the field.

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Raman, Narmadaa, Siti A. M. Imran, Khairul Bariah Ahmad Amin Noordin, Wan Safwani Wan Kamarul Zaman, and Fazlina Nordin. "Mechanotransduction in Mesenchymal Stem Cells (MSCs) Differentiation: A Review." International Journal of Molecular Sciences 23, no. 9 (April 21, 2022): 4580. http://dx.doi.org/10.3390/ijms23094580.

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Mechanotransduction is the process by which physical force is converted into a biochemical signal that is used in development and physiology; meanwhile, it is intended for the ability of cells to sense and respond to mechanical forces by activating intracellular signals transduction pathways and the relative phenotypic adaptation. It encompasses the role of mechanical stimuli for developmental, morphological characteristics, and biological processes in different organs; the response of cells to mechanically induced force is now also emerging as a major determinant of disease. Due to fluid shear stress caused by blood flowing tangentially across the lumen surface, cells of the cardiovascular system are typically exposed to a variety of mechanotransduction. In the body, tissues are continuously exposed to physical forces ranging from compression to strain, which is caused by fluid pressure and compressive forces. Only lately, though, has the importance of how forces shape stem cell differentiation into lineage-committed cells and how mechanical forces can cause or exacerbate disease besides organizing cells into tissues been acknowledged. Mesenchymal stem cells (MSCs) are potent mediators of cardiac repair which can secret a large array of soluble factors that have been shown to play a huge role in tissue repair. Differentiation of MSCs is required to regulate mechanical factors such as fluid shear stress, mechanical strain, and the rigidity of the extracellular matrix through various signaling pathways for their use in regenerative medicine. In the present review, we highlighted mechanical influences on the differentiation of MSCs and the general factors involved in MSCs differentiation. The purpose of this study is to demonstrate the progress that has been achieved in understanding how MSCs perceive and react to their mechanical environment, as well as to highlight areas where more research has been performed in previous studies to fill in the gaps.

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Primasatya, Dimas, Erry Rimawan, Hendi Herlambang, and Horas Canman S. "Simulation of the Cardiovascular Mechanical System Based on Pressure-Flow Model Rest Condition." International Journal of Innovative Science and Research Technology 5, no. 7 (July 19, 2020): 104–15. http://dx.doi.org/10.38124/ijisrt20jul031.

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Non-invasive measurement method has made rapid developments in the field of biomedical engineering. One of research is impedance cardiography (ICG), which provide information of pulsation basic. By knowing this kind of measurement technique, it will assist inspection of the patient's physiological condition with cardiovascular system. This research is aimed to determine the mechanical characteristics of the cardiovascular system in the human body such as a wave graph of pressure, flow, and volume, based on pressure–flow model in rest condition, and analyze the simulation results by implementing state of the physiology cardiovascular disease. To obtain the wave chart that is modeled by the cardiovascular system using a lumped parameter method, formulate the differential equations of the pressure–flow dynamics equation for an incompressible fluid in a segment of a cylindrical elastic tube and simulate the model using the Simulink toolboxes from Matlab R2008b. The simulation with lumped parameter method resulted wave graphics of pressure, flow, and volume of physiological state a person in rest condition, the left ventricular pressure is 120 mmHg , right ventricular pressure is 30 mmHg , left ventricular outflow is 800 mL / sec and volume in the left ventricle is 160 mL . By implementing the simulation have been developed on the physiological state of cardiovascular disease, hypertension occurs when the arteries resistance R3i = 0.61 mmHg × s mL with the pressure of the left ventricle is 145 mmHg. For coronary heart condition, ventricular pressure decreased until 82 mmHg in the value of the coronary arteries resistance is R3o = 0.852 mmHg × s mL. This research assumed heart haves the character of passive because there is no feedback signal that can compensate if the pressure in the systemic circulation is reduced. The research can be concluded that the graph from simulation shows the results are not much different from the reference chart, this results indicates that the equation and the simulation was able to reflect on the human circulatory physiological circumstances. A little different of a graphic simulation result due to differences in the parameters and assumptions used.

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Grinstein, J., P. J. Blanco, C. A. Bulant, R. Torii, C. V. Bourantas, P. A. Lemos, and H. Garcia-Garcia. "Combining Invasive Cardiopulmonary Exercise Testing with Computational Fluid Dynamics to Better Understand LVAD Fluid Mechanics during Exercise." Journal of Heart and Lung Transplantation 40, no. 4 (April 2021): S450—S451. http://dx.doi.org/10.1016/j.healun.2021.01.1254.

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Journal articles on the topic 'Cardiovascular fluid mechanic'

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