Articles de revues : « Cardiovascular fluid dynamic »

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Felipini, Celso Luiz, Aron José Pazin de Andrade, Júlio César Lucchi, Jeison Willian Gomes da Fonseca et Denys Nicolosi. « An Electro-Fluid-Dynamic Simulator for the Cardiovascular System ». Artificial Organs 32, n^o 4 (avril 2008) : 349–54. http://dx.doi.org/10.1111/j.1525-1594.2008.00553.x.

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Brien, Lori Dugan, Marilyn H. Oermann, Margory Molloy et Catherine Tierney. « Implementing a Goal-Directed Therapy Protocol for Fluid Resuscitation in the Cardiovascular Intensive Care Unit ». AACN Advanced Critical Care 31, n^o 4 (15 décembre 2020) : 364–70. http://dx.doi.org/10.4037/aacnacc2020582.

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Background Balancing fluid administration and titration of vasoactive medications is critical to preventing postoperative complications in cardiac surgical patients. Objective To evaluate the impact of implementing a goal-directed therapy protocol in the cardiovascular intensive care unit on total intravenous fluids administered on the day of surgery, rates of acute kidney injury, and hospital length of stay. Methods A fluid resuscitation protocol using dynamic assessment of fluid responsiveness with stroke volume index was developed, and nurses were prepared for its implementation using simulation training. Results After implementation of the new protocol, the total amount of intravenous fluids administered on the day of surgery was significantly reduced (P = .003). There were no significant changes in hospital length of stay (P = .83) or rates of acute kidney injury (P = .86). There were significant increases in nurses’ knowledge of (P < .001) and confidence in (P < .001) fluid resuscitation and titration of vasoactive medications after simulation training. Conclusions Use of a fluid resuscitation protocol resulted in a reduction in the amount of intravenous fluids administered on the day of surgery. The simulation training increased nurses’ knowledge of and confidence in fluid resuscitation and titration of vasoactive medications.

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Benes, Jan, Mikhail Kirov, Vsevolod Kuzkov, Mitja Lainscak, Zsolt Molnar, Gorazd Voga et Xavier Monnet. « Fluid Therapy : Double-Edged Sword during Critical Care ? » BioMed Research International 2015 (2015) : 1–14. http://dx.doi.org/10.1155/2015/729075.

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Fluid therapy is still the mainstay of acute care in patients with shock or cardiovascular compromise. However, our understanding of the critically ill pathophysiology has evolved significantly in recent years. The revelation of the glycocalyx layer and subsequent research has redefined the basics of fluids behavior in the circulation. Using less invasive hemodynamic monitoring tools enables us to assess the cardiovascular function in a dynamic perspective. This allows pinpointing even distinct changes induced by treatment, by postural changes, or by interorgan interactions in real time and enables individualized patient management. Regarding fluids as drugs of any other kind led to the need for precise indication, way of administration, and also assessment of side effects. We possess now the evidence that patient centered outcomes may be altered when incorrect time, dose, or type of fluids are administered. In this review, three major features of fluid therapy are discussed: the prediction of fluid responsiveness, potential harms induced by overzealous fluid administration, and finally the problem of protocol-led treatments and their timing.

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Baker, R. Scott, Christopher T. Lam, Emily A. Heeb et Pirooz Eghtesady. « Dynamic fluid shifts induced by fetal bypass ». Journal of Thoracic and Cardiovascular Surgery 137, n^o 3 (mars 2009) : 714–22. http://dx.doi.org/10.1016/j.jtcvs.2008.09.023.

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Slack, Steven M., et Vincent T. Turitto. « Chapter 2 Fluid dynamic and hemorheologic considerations ». Cardiovascular Pathology 2, n^o 3 (juillet 1993) : 11–21. http://dx.doi.org/10.1016/1054-8807(93)90043-2.

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Ravi, Chandni, et Daniel W. Johnson. « Optimizing Fluid Resuscitation and Preventing Fluid Overload in Patients with Septic Shock ». Seminars in Respiratory and Critical Care Medicine 42, n^o 05 (20 septembre 2021) : 698–705. http://dx.doi.org/10.1055/s-0041-1733898.

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AbstractIntravenous fluid administration remains an important component in the care of patients with septic shock. A common error in the treatment of septic shock is the use of excessive fluid in an effort to overcome both hypovolemia and vasoplegia. While fluids are necessary to help correct the intravascular depletion, vasopressors should be concomitantly administered to address vasoplegia. Excessive fluid administration is associated with worse outcomes in septic shock, so great care should be taken when deciding how much fluid to give these vulnerable patients. Simple or strict “recipes” which mandate an exact amount of fluid to administer, even when weight based, are not associated with better outcomes and therefore should be avoided. Determining the correct amount of fluid requires the clinician to repeatedly assess and consider multiple variables, including the fluid deficit, organ dysfunction, tolerance of additional fluid, and overall trajectory of the shock state. Dynamic indices, often involving the interaction between the cardiovascular and respiratory systems, appear to be superior to traditional static indices such as central venous pressure for assessing fluid responsiveness. Point-of-care ultrasound offers the bedside clinician a multitude of applications which are useful in determining fluid administration in septic shock. In summary, prevention of fluid overload in septic shock patients is extremely important, and requires the careful attention of the entire critical care team.

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Mazzoni, M. C., P. Borgstrom, K. E. Arfors et M. Intaglietta. « Dynamic fluid redistribution in hyperosmotic resuscitation of hypovolemic hemorrhage ». American Journal of Physiology-Heart and Circulatory Physiology 255, n^o 3 (1 septembre 1988) : H629—H637. http://dx.doi.org/10.1152/ajpheart.1988.255.3.h629.

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A mathematical description of blood volume restoration after hemorrhage with resuscitative fluids, particularly hyperosmotic solutions, is presented. It is based on irreversible thermodynamic transport equations and known physiological data. The model shows that after a 20% hemorrhage, the rapid addition of a hypertonic (7.5% NaCl)-hyperoncotic (6% Dextran 70) solution amounting to one-seventh of the shed blood volume reestablishes blood volume within 1 min. Measurements of systemic hematocrit, hemoglobin concentration, and plasma osmolality taken from 13 experiments on anesthetized rabbits verify this prediction. The model shows that immediately after hyperosmotic infusion, water shifts into the plasma first from red blood cells and endothelium and then from the interstitium and tissue cells. The increase in blood volume is transitory; however, it occurs in a fraction of the time compared with isoosmotic fluids at the same infusion rate and is partially sustained by Dextran 70. We theorize that the concurrent hemodilution and endothelial cell shrinkage during hyperosmotic infusion lead to a decreased capillary hydraulic resistance, an effect that is even more significant in capillaries with swollen endothelium. Our results support the significant role of an osmotic mechanism during hyperosmotic resuscitation in quickly restoring blood volume with the added benefit of improved tissue perfusion.

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Mazzoni, M. C., P. Borgstrom, K.-E. Afors et M. Intaglietta. « Dynamic fluid redistribution in hyperosmotic resuscitation of hypovolemic hemorrhage ». Resuscitation 18, n^o 1 (octobre 1989) : 112–13. http://dx.doi.org/10.1016/0300-9572(89)90123-8.

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Stühle, Sebastian, Daniel Wendt, Guojun Hou, Hermann Wendt, Matthias Thielmann, Heinz Jakob et Wojciech Kowalczyk. « Fluid Dynamic Investigation of the ATS 3F Enable Sutureless Heart Valve ». Innovations : Technology and Techniques in Cardiothoracic and Vascular Surgery 6, n^o 1 (janvier 2011) : 37–44. http://dx.doi.org/10.1097/imi.0b013e31820c0f0c.

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Objective Currently, sutureless heart valves (SHV) reveal good clinical results during aortic valve replacement. The aim of this study was to evaluate the fluid dynamics of the ATS 3F Enable SHV in the ascending aorta and their influence on the aortic wall in an in vitro setup. Methods A two-dimensional particle image velocimetry study with an image rate of 15 Hz was conducted to evaluate the fluid dynamics of the SHV in the aortic flow field. The prosthesis (diameter, 23 mm) was placed inside a silicone mock aorta under pulsatile flow conditions. Velocities, vorticity, and strain rate were obtained and calculated with a fixed frequency (70 Hz) at constant stroke volume (70 mL). Results 3F Enable showed a jet flow type profile with a maximum velocity of 1.01 ± 0.13 m/s during peak flow phase (PFP). The jet flow was surrounded by ambilateral vortices with a slightly higher percentage of clockwise than counterclockwise vorticity (377 ± 57/s vs 389 ± 76/s), strain rate (370 ± 79/s for elongation vs — 370 ± 102/s for contraction) was nearly similar. The point-of-interest analysis revealed a higher velocity for bottom compared with upper aortic wall (0.28 ± 0.07 m/s vs 0.31 ± 0.06 m/s, P = 0.024). All values were lower during acceleration and deceleration phase compared with PFP. Conclusions The peak flow of the 3F Enable SHV seems to be little higher compared with native aortic valves, thus simulating nearly physiologic conditions. Vorticity and strain rate are high during PFP and low during other phases and might have an influence on the aortic wall as well.

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Pinsky, M. R., P. Brophy, J. Padilla, E. Paganini et N. Pannu. « Fluid and Volume Monitoring ». International Journal of Artificial Organs 31, n^o 2 (février 2008) : 111–26. http://dx.doi.org/10.1177/039139880803100205.

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Background Fluid resuscitation is not only used to prevent acute kidney injury (AKI) but fluid management is also a cornerstone of treatment for patients with established AKI and renal failure. Ultrafiltration removes volume initially from the intravascular compartment inducing a relative degree of hypovolemia. Normal reflex mechanisms attempt to sustain blood pressure constant despite marked changes in blood volume and cardiac output. Thus, compensated shock with a normal blood pressure is a major cause of AKI or exacerbations of AKI during ultrafiltration. Methods We undertook a systematic review of the literature using MEDLINE, Google Scholar and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated clinical practice recommendations and/or directions for future research. Results We defined three aspects of fluid monitoring: i) normal and pathophysiological cardiovascular mechanisms; ii) measures of volume responsiveness and impending cardiovascular collapse during volume removal, and; iii) measured indices of each using non-invasive and minimally invasive continuous and intermittent monitoring techniques. The evidence documents that AKI can occur in the setting of normotensive hypovolemia and that under-resuscitation represents a major cause of both AKI and mortality ion critically ill patients. Traditional measures of intravascular volume and ventricular filling do not predict volume responsiveness whereas dynamic functional hemodynamic markers, such as pulse pressure or stroke volume variation during positive pressure breathing or mean flow changes with passive leg raising are highly predictive of volume responsiveness. Numerous commercially-available devices exist that can acquire these signals. Conclusions Prospective clinical trials using functional hemodynamic markers in the diagnosis and management of AKI and volume status during ultrafiltration need to be performed. More traditional measure of preload be abandoned as marked of volume responsiveness though still useful to assess overall volume status.

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Zuin, Marco, Gianluca Rigatelli, Giovanni Zuliani et Loris Roncon. « New prediction tools for coronary plaque erosion : Don't forget computational fluid dynamic analysis ». Atherosclerosis 323 (avril 2021) : 54–55. http://dx.doi.org/10.1016/j.atherosclerosis.2021.03.001.

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Nguyen, Thach, Marco Zuni, Nguyen Thanh Luan, Nguyen Ngoc Huyen Vy, Kim Truong, Thao Dang, Tu NT Nguyen, Tarneem Darwish, Gianluca Rigatelli et Ernest Talarico. « GW29-e0867 Demonstration of Cavitation in the Coronary Arteries by Computational Fluid Dynamic ». Journal of the American College of Cardiology 72, n^o 16 (octobre 2018) : C72. http://dx.doi.org/10.1016/j.jacc.2018.08.414.

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Kamali Shahri, Seyed Mehdi, Christian Contarino, Francesco Chifari, Morteza Mahmoudi et Simon Gelman. « Function of arteries and veins in conditions of simulated cardiac arrest ». BioImpacts 11, n^o 2 (7 mars 2021) : 157–64. http://dx.doi.org/10.34172/bi.2021.13.

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Introduction: The study examined the behavior of vasculature in conditions of eliminated cardiac function using mathematical modeling. In addition, we addressed the question of whether the stretch-recoil capability of veins, at least in part accounts for the slower response to simulated cardiac arrest. Methods: In the first set of computational experiments, blood flow and pressure patterns in veins and arteries during the first few seconds after cardiac arrest were assessed via a validated multi-scale mathematical model of the whole cardiovascular system, comprising cardiac dynamics, arterial and venous blood flow dynamics, and microcirculation. In the second set of experiments, the effects of stretch-recoil zones of venous vessels with different diameters and velocities on blood velocity and dynamic pressure analyzed using computational fluid dynamics (CFD) modeling. Results: In the first set of experiments, measurement of changes in velocity, dynamic pressure, and fluid flow revealed that the venous system responded to cardiac arrest more slowly compared to the arteries. This disparity might be due to the intrinsic characteristics of the venous system, including stretch-recoil and elastic fiber composition. In the second set of experiments, we attempted to determine the role of the stretch-recoil capability of veins in the slower response to cardiac arrest. During the second set of experiments, we found that this recoil behavior increased dynamic pressure, velocity, and blood flow. The enhancement in dynamic pressure through combining the results from both experiments yielded a 15-40% increase in maximum dynamic pressure due to stretch-recoil, depending on vein diameter under normal conditions. Conclusion: In the situation of cardiac arrest, the vein geometry changes continue, promoting smooth responses of the venous system. Moreover, the importance of such vein behavior in blood displacement may grow as the pressure on the venous side gradually decreases with time. Our experiments suggest that the driving force for venous return is the pressure difference that remains within the venous system after the energy coming from every ventricular systole spent to overcome the resistance created by arterial and capillary systems.

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Corno, A. F., et E. S. Mickaily-Huber. « Comparative computational fluid dynamic study of two distal Contegra conduit anastomoses ». Interactive CardioVascular and Thoracic Surgery 7, n^o 1 (1 février 2008) : 1–5. http://dx.doi.org/10.1510/icvts.2007.162412.

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Lardo, Albert C., Steven A. Webber, Ingeborg Friehs, Pedro J. del Nido et Edward G. Cape. « Fluid dynamic comparison of intra-atrial and extracardiac total cavopulmonary connections ». Journal of Thoracic and Cardiovascular Surgery 117, n^o 4 (avril 1999) : 697–704. http://dx.doi.org/10.1016/s0022-5223(99)70289-8.

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Bucurenciu, Cristian, Victor S. Costache et Gabriela S. Cândea. « Study of aortic dissections treatment. Segmentation, simulation and valiadation of surgical results ». MATEC Web of Conferences 290 (2019) : 04004. http://dx.doi.org/10.1051/matecconf/201929004004.

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Nowadays, Computational Fluid Dynamics (CFD) it’s seen as the new trend in the management of aortic pathologies. Together with visualization capabilities of cardiovascular magnetic resonance (CMR) and computed tomography (CT) imaging, real time segmentation (volumetric) models further used as meshes in Computational Fluid Dynamic supply to the clinicians an innovative and extensive decision-making system. In the present paper, we identified and analysed the clinical indicators (lumens diameters, fenestrated area and blood volume) monitored by clinicians to evaluate the patient’ condition before and after the intervention. In order to achieve the targeted aims, we used CT scans as input data (segmented with MIMICS software) and output 3D models (3matic), further processed to mesh model in ANSYS software. Computational results validate the improved patient’ condition, meaning the blood velocity tend to have values to normal flowing conditions. As a conclusion, the linear modification of velocity can be used in further investigations as an input value of pathology treatment

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Hull, Jeffrey E., Boris V. Balakin, Brad M. Kellerman et David K. Wrolstad. « Computational fluid dynamic evaluation of the side-to-side anastomosis for arteriovenous fistula ». Journal of Vascular Surgery 58, n^o 1 (juillet 2013) : 187–93. http://dx.doi.org/10.1016/j.jvs.2012.10.070.

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Capelli, Claudio, Emilie Sauvage, Giuliano Giusti, Giorgia M. Bosi, Hopewell Ntsinjana, Mario Carminati, Graham Derrick et al. « Patient-specific simulations for planning treatment in congenital heart disease ». Interface Focus 8, n^o 1 (15 décembre 2017) : 20170021. http://dx.doi.org/10.1098/rsfs.2017.0021.

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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. A cohort of 12 patients with congenital heart disease who were referred for percutaneous pulmonary valve implantation, stenting of aortic coarctation and surgical repair of double-outlet right ventricle was included in this study. Image data routinely acquired for clinical assessment were post-processed to set up patient-specific models and test device implantation and surgery. Finite-element and computational fluid dynamics analyses were run to assess feasibility of each intervention and provide some guidance. Results showed good agreement between simulations and clinical decision including feasibility, device choice and fluid-dynamic parameters. The promising results of this pilot study support translation of computer simulations as tools for personalization of cardiovascular treatments.

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Park, Jun-Bean, Gilwoo Choi, Eun Ju Chun, Hyun Jin Kim, Jonghanne Park, Ji-Hyun Jung, Min-Ho Lee et al. « Computational fluid dynamic measures of wall shear stress are related to coronary lesion characteristics ». Heart 102, n^o 20 (14 juin 2016) : 1655–61. http://dx.doi.org/10.1136/heartjnl-2016-309299.

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Kimball, Brian P., Nikolas Dafopoulos et Victor LiPreti. « Comparative evaluation of coronary stenoses using fluid dynamic equations and standard quantitative coronary arteriography ». American Journal of Cardiology 64, n^o 1 (juillet 1989) : 6–10. http://dx.doi.org/10.1016/0002-9149(89)90644-9.

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Kim, Youngho, et 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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Santa-Maria, Ana R., Fruzsina R. Walter, Ricardo Figueiredo, András Kincses, Judit P. Vigh, Marjolein Heymans, Maxime Culot et al. « Flow induces barrier and glycocalyx-related genes and negative surface charge in a lab-on-a-chip human blood-brain barrier model ». Journal of Cerebral Blood Flow & ; Metabolism 41, n^o 9 (9 février 2021) : 2201–15. http://dx.doi.org/10.1177/0271678x21992638.

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Microfluidic lab-on-a-chip (LOC) devices allow the study of blood-brain barrier (BBB) properties in dynamic conditions. We studied a BBB model, consisting of human endothelial cells derived from hematopoietic stem cells in co-culture with brain pericytes, in an LOC device to study fluid flow in the regulation of endothelial, BBB and glycocalyx-related genes and surface charge. The highly negatively charged endothelial surface glycocalyx functions as mechano-sensor detecting shear forces generated by blood flow on the luminal side of brain endothelial cells and contributes to the physical barrier of the BBB. Despite the importance of glycocalyx in the regulation of BBB permeability in physiological conditions and in diseases, the underlying mechanisms remained unclear. The MACE-seq gene expression profiling analysis showed differentially expressed endothelial, BBB and glycocalyx core protein genes after fluid flow, as well as enriched pathways for the extracellular matrix molecules. We observed increased barrier properties, a higher intensity glycocalyx staining and a more negative surface charge of human brain-like endothelial cells (BLECs) in dynamic conditions. Our work is the first study to provide data on BBB properties and glycocalyx of BLECs in an LOC device under dynamic conditions and confirms the importance of fluid flow for BBB culture models.

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Sluysmans, Thierry, et Steven D. Colan. « Theoretical and empirical derivation of cardiovascular allometric relationships in children ». Journal of Applied Physiology 99, n^o 2 (août 2005) : 445–57. http://dx.doi.org/10.1152/japplphysiol.01144.2004.

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Basic fluid dynamic principles were used to derive a theoretical model of optimum cardiovascular allometry, the relationship between somatic and cardiovascular growth. The validity of the predicted models was then tested against the size of 22 cardiovascular structures measured echocardiographically in 496 normal children aged 1 day to 20 yr, including valves, pulmonary arteries, aorta and aortic branches, pulmonary veins, and left ventricular volume. Body surface area (BSA) was found to be a more important determinant of the size of each of the cardiovascular structures than age, height, or weight alone. The observed vascular and valvar dimensions were in agreement with values predicted from the theoretical models. Vascular and valve diameters related linearly to the square root of BSA, whereas valve and vascular areas related to BSA. The relationship between left ventricular volume and body size fit a complex model predicted by the nonlinear decrease of heart rate with growth. Overall, the relationship between cardiac output and body size is the fundamental driving factor in cardiovascular allometry.

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Domanin, Maurizio, Daniele Bissacco, Davide Le Van et Christian Vergara. « Computational fluid dynamic comparison between patch-based and primary closure techniques after carotid endarterectomy ». Journal of Vascular Surgery 67, n^o 3 (mars 2018) : 887–97. http://dx.doi.org/10.1016/j.jvs.2017.08.094.

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Garcia, Mario J., Pieter Vandervoort, William J. Stewart, Bruce W. Lytle, Delos M. Cosgrove, James D. Thomas et Brian P. Griffin. « Mechanisms of hemolysis with mitral prosthetic regurgitation study using transesophageal echocardiography and fluid dynamic simulation ». Journal of the American College of Cardiology 27, n^o 2 (février 1996) : 399–406. http://dx.doi.org/10.1016/0735-1097(95)00403-3.

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Tanaka, Rie, Tohru Tani, Atsushi Yamada, Soichiro Tani, Khiem Tran Dang, Norihisa Nitta, Takahisa Tabata, Shintaro Muraoka, Tsutomu Yoneyama et Shigeru Sanada. « Correlations between cardiovascular parameters and image parameters on dynamic chest radiographs in a porcine model under fluid loading ». Radiological Physics and Technology 14, n^o 3 (21 juin 2021) : 288–96. http://dx.doi.org/10.1007/s12194-021-00626-2.

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Oude Egbrink, M. G., G. J. Tangelder, D. W. Slaaf et R. S. Reneman. « Fluid dynamics and the thromboembolic reaction in mesenteric arterioles and venules ». American Journal of Physiology-Heart and Circulatory Physiology 260, n^o 6 (1 juin 1991) : H1826—H1833. http://dx.doi.org/10.1152/ajpheart.1991.260.6.h1826.

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In the mesentery of the anesthetized rabbit, the thromboembolic reaction after wall puncture lasts six times longer in arterioles than in venules, a difference that cannot be explained by fluid dynamic conditions before puncture. In the present study, it was investigated whether this difference in response between arterioles and venules results from a different degree of stenosis by the thrombus and/or a difference in velocity changes resulting in a different pressure drop over the thrombus. Arteriolar and venular mean red blood cell velocity and vessel diameter were measured before puncture and after this injury in the stenosed vessel segment and upstream. Thrombi with similar heights were formed in arterioles and venules and induced similar degrees of stenosis. A surface area reduction less than 55% induced only a small and similar decrease in volume flow (less than 10%) in arterioles and venules. Reduced velocity, a measure of wall shear rate, increased similarly in both vessel types for similar degrees of stenosis. In conclusion, changes in fluid dynamic factors, as induced by thrombus formation, cannot be held responsible for the difference in thromboembolic reaction between arterioles and venules.

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Dekker, Marijke J. E., Frank M. van der Sande, Florence van den Berghe, Karel M. L. Leunissen et Jeroen P. Kooman. « Fluid Overload and Inflammation Axis ». Blood Purification 45, n^o 1-3 (2018) : 159–65. http://dx.doi.org/10.1159/000485153.

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Extracellular fluid overload (FO), which is assessed using bioimpedance technologies, is an important predictor of outcome in dialysis patients and in patients with early stages of chronic kidney disease. While traditional cardiovascular abnormalities are assumed to mediate this risk, recently also, the importance of noncardiovascular factors, such as systemic inflammation and malnutrition has been shown. While both FO and inflammation are independent risk factors for mortality, recent studies have shown that their combined presence can lead to a cumulative risk profile. From a pathophysiologic viewpoint, FO and inflammation can also be mutually reinforcing. Inflammation could contribute to FO by hypoalbuminemia, capillary leakage, and a (unnoticed) decline in lean and/or fat tissue mass resulting in incorrect estimation of dry weight. Reciprocally, FO could lead to inflammation by the translocation of endotoxins through a congested bowel wall or by a proinflammatory effect of tissue sodium. The relative importance of these putative factors is, however, not clear yet and epidemiological studies have shown no clear temporal direction regarding the relationship between FO and inflammation. FO and inflammation appear to be part of (dynamic) clusters of risk factors, including malnutrition and hyponatremia. Technology-guided fluid management of the often vulnerable dialysis patient with FO and inflammation cannot yet be based on evidence from randomized controlled trials, in which these specific patients were in general not included. In the absence of those trials, treatment should be based on identifying actionable causes of inflammation and on the judicious removal of excess volume based on frequent clinical reassessment.

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Fot, Evgenia V., Natalia N. Izotova, Aleksei A. Smetkin, Vsevolod V. Kuzkov et Mikhail Y. Kirov. « Dynamic Tests to Predict Fluid Responsiveness After Off-Pump Coronary Artery Bypass Grafting ». Journal of Cardiothoracic and Vascular Anesthesia 34, n^o 4 (avril 2020) : 926–31. http://dx.doi.org/10.1053/j.jvca.2019.09.013.

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Kurzhals, Anja, Christoph Brandt-Wunderlich, Niels Grabow, Wolfram Schmidt et Klaus-Peter Schmitz. « Dynamic image analysis of transparent particles released during the simulated use test of cardiovascular devices ». Current Directions in Biomedical Engineering 5, n^o 1 (1 septembre 2019) : 203–6. http://dx.doi.org/10.1515/cdbme-2019-0052.

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AbstractFor product approval of coated cardiovascular devices, the assessment of particle release is essential. Particularly challenging are delivery systems equipped with hydrophilic coatings releasing highly transparent particles. The aim of this study was to compare two different methods of particle counting, namely the light obscuration method and the dynamic image analysis (DIA), with respect to optical transparent particles. The particles were collected during the simulated use of cardiovascular catheters and analysed in suspension with a dynamic imaging device (FlowCam, Fluid Imaging Technologies). Particles were detected by a greyscale threshold and imaged to analyse their shape and transparency. The statistical influence of the threshold on particle counts and size distribution was determined and compared to light obscuration particle counting (Model 9703 with sensor HRLD 400CE, HIAC ROYCO). The light obscuration method provided lower particle counts in suspensions containing a high amount of transparent particles. The lower the detection threshold, the higher the particle counts were. In conclusion, it is important to adapt the threshold value for samples that are expected to contain a high amount of transparent particles. DIA may be suggested as a valuable additional method for particulate analysis.

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Fang, Yuanjian, Lei Huang, Xiaoyu Wang, Xiaoli Si, Cameron Lenahan, Hui Shi, Anwen Shao et al. « A new perspective on cerebrospinal fluid dynamics after subarachnoid hemorrhage : From normal physiology to pathophysiological changes ». Journal of Cerebral Blood Flow & ; Metabolism 42, n^o 4 (22 novembre 2021) : 543–58. http://dx.doi.org/10.1177/0271678x211045748.

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Knowledge about the dynamic metabolism and function of cerebrospinal fluid (CSF) physiology has rapidly progressed in recent decades. It has traditionally been suggested that CSF is produced by the choroid plexus and drains to the arachnoid villi. However, recent findings have revealed that the brain parenchyma produces a large portion of CSF and drains through the perivascular glymphatic system and meningeal lymphatic vessels into the blood. The primary function of CSF is not limited to maintaining physiological CNS homeostasis but also participates in clearing waste products resulting from neurodegenerative diseases and acute brain injury. Aneurysmal subarachnoid hemorrhage (SAH), a disastrous subtype of acute brain injury, is associated with high mortality and morbidity. Post-SAH complications contribute to the poor outcomes associated with SAH. Recently, abnormal CSF flow was suggested to play an essential role in the post-SAH pathophysiological changes, such as increased intracerebral pressure, brain edema formation, hydrocephalus, and delayed blood clearance. An in-depth understanding of CSF dynamics in post-SAH events would shed light on potential development of SAH treatment options. This review summarizes and updates the latest physiological characteristics of CSF dynamics and discusses potential pathophysiological changes and therapeutic targets after SAH.

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Li, Jianping, Yanjun Gong, Tieci Yi, Tao Hong, Zhaoping Liu, Bo Zheng et Yunlong Huo. « TCT-323 Angiography-Derived Contrast Fractional Flow Reserve From a Specially Designed Computational Fluid Dynamic Method ». Journal of the American College of Cardiology 74, n^o 13 (octobre 2019) : B321. http://dx.doi.org/10.1016/j.jacc.2019.08.403.

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Lin, W. C. Patrick, Matthew G. Doyle, S. Lucy Roche, Osami Honjo, Thomas L. Forbes et Cristina H. Amon. « Computational fluid dynamic simulations of a cavopulmonary assist device for failing Fontan circulation ». Journal of Thoracic and Cardiovascular Surgery 158, n^o 5 (novembre 2019) : 1424–33. http://dx.doi.org/10.1016/j.jtcvs.2019.03.008.

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Koratala, Abhilash, Claudio Ronco et Amir Kazory. « Need for Objective Assessment of Volume Status in Critically Ill Patients with COVID-19 : The Tri-POCUS Approach ». Cardiorenal Medicine 10, n^o 4 (2020) : 209–16. http://dx.doi.org/10.1159/000508544.

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As the coronavirus disease 2019 (COVID-19) continues to spread across the globe, the knowledge of its epidemiology, clinical features, and management is rapidly evolving. Nevertheless, the data on optimal fluid management strategies for those who develop critical illness remain sparse. Adding to the challenge, the fluid volume status of these patients has been found to be dynamic. Some present with several days of malaise, gastrointestinal symptoms, and consequent hypovolemia requiring aggressive fluid resuscitation, while a subset develop acute respiratory distress syndrome with renal dysfunction and lingering congestion necessitating restrictive fluid management. Accurate objective assessment of volume status allows physicians to tailor the fluid management goals throughout this wide spectrum of critical illness. Conventional point-of-care ultrasonography (POCUS) enables the reliable assessment of fluid status and reducing the staff exposure. However, due to specific characteristics of COVID-19 (e.g., rapidly expanding lung lesions), a single imaging method such as lung POCUS will have significant limitations. Herein, we suggest a Tri-POCUS approach that represents concurrent bedside assessment of the lungs, heart, and the venous system. This combinational approach is likely to overcome the limitations of the individual methods and provide a more precise evaluation of the volume status in critically ill patients with COVID-19.

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Broch, Ole, Jochen Renner, Patrick Meybohm, Martin Albrecht, Jan Höcker, Assad Haneya, Markus Steinfath, Berthold Bein et Matthias Gruenewald. « Dynamic Variables Fail to Predict Fluid Responsiveness in an Animal Model With Pericardial Effusion ». Journal of Cardiothoracic and Vascular Anesthesia 30, n^o 5 (octobre 2016) : 1205–11. http://dx.doi.org/10.1053/j.jvca.2016.03.151.

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Cheng, Stephen W. K., Edward S. K. Lam, George S. K. Fung, Pei Ho, Albert C. W. Ting et Kwok W. Chow. « A computational fluid dynamic study of stent graft remodeling after endovascular repair of thoracic aortic dissections ». Journal of Vascular Surgery 48, n^o 2 (août 2008) : 303–10. http://dx.doi.org/10.1016/j.jvs.2008.03.050.

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Shadden, Shawn C., Ian Carr, Naohiko Nemoto, John R. Lesser et Robert S. Schwartz. « EMBOLIC PARTICLES SHOW SIZE DEPENDENT PREDILECTION FOR CEREBRAL VERSUS PERIPHERAL ARTERIES : RESULTS FROM COMPUTATIONAL FLUID DYNAMIC MODELING ». Journal of the American College of Cardiology 61, n^o 10 (mars 2013) : E2044. http://dx.doi.org/10.1016/s0735-1097(13)62044-6.

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Canaud, Bernard, Allan Collins et Frank Maddux. « The renal replacement therapy landscape in 2030 : reducing the global cardiovascular burden in dialysis patients ». Nephrology Dialysis Transplantation 35, Supplement_2 (1 mars 2020) : ii51—ii57. http://dx.doi.org/10.1093/ndt/gfaa005.

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Abstract Despite the significant progress made in understanding chronic kidney disease and uraemic pathophysiology, use of advanced technology and implementation of new strategies in renal replacement therapy, the clinical outcomes of chronic kidney disease 5 dialysis patients remain suboptimal. Considering residual suboptimal medical needs of short intermittent dialysis, it is our medical duty to revisit standards of dialysis practice and propose new therapeutic options for improving the overall effectiveness of dialysis sessions and reduce the burden of stress induced by the therapy. Several themes arise to address the modifiable components of the therapy that are aimed at mitigating some of the cardiovascular risks in patients with end-stage kidney disease. Among them, five are of utmost importance and include: (i) enhancement of treatment efficiency and continuous monitoring of dialysis performances; (ii) prevention of dialysis-induced stress; (iii) precise handling of sodium and fluid balance; (iv) moving towards heparin-free dialysis; and (v) customizing electrolyte prescriptions. In summary, haemodialysis treatment in 2030 will be substantially more personalized to the patient, with a clear focus on cardioprotection, volume management, arrhythmia surveillance, avoidance of anticoagulation and the development of more dynamic systems to align the fluid and electrolyte needs of the patient on the day of the treatment to their particular circumstances.

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Masuzawa, Toru, Akiko Ohta, Nobuatu Tanaka, Yi Qian et Tomonori Tsukiya. « Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysis ». Journal of Artificial Organs 12, n^o 3 (septembre 2009) : 150–59. http://dx.doi.org/10.1007/s10047-009-0459-2.

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Nguyen and, T. T., Y. Biadillah, R. Mongrain, J. Brunette, and, J. C. Tardif et O. F. Bertrand. « A Method for Matching the Refractive Index and Kinematic Viscosity of a Blood Analog for Flow Visualization in Hydraulic Cardiovascular Models ». Journal of Biomechanical Engineering 126, n^o 4 (1 août 2004) : 529–35. http://dx.doi.org/10.1115/1.1785812.

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In this work, we propose a simple method to simultaneously match the refractive index and kinematic viscosity of a circulating blood analog in hydraulic models for optical flow measurement techniques (PIV, PMFV, LDA, and LIF). The method is based on the determination of the volumetric proportions and temperature at which two transparent miscible liquids should be mixed to reproduce the targeted fluid characteristics. The temperature dependence models are a linear relation for the refractive index and an Arrhenius relation for the dynamic viscosity of each liquid. Then the dynamic viscosity of the mixture is represented with a Grunberg-Nissan model of type 1. Experimental tests for acrylic and blood viscosity were found to be in very good agreement with the targeted values (measured refractive index of 1.486 and kinematic viscosity of 3.454 milli-m2/s with targeted values of 1.47 and 3.300 milli-m2/s).

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Asada, Satoshi, Masaaki Yamagishi, Keiichi Itatani, Yoshinobu Maeda, Satoshi Taniguchi, Shuhei Fujita, Hisayuki Hongu et Hitoshi Yaku. « Early outcomes and computational fluid dynamic analyses of chimney reconstruction in the Norwood procedure ». Interactive CardioVascular and Thoracic Surgery 29, n^o 2 (15 mars 2019) : 252–59. http://dx.doi.org/10.1093/icvts/ivz040.

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Abstract OBJECTIVES The ideal configuration of a reconstructed aortic arch in the Norwood procedure for hypoplastic left heart syndrome is still a matter of debate. Chimney reconstruction was developed to avoid postoperative complications and turbulent flow in the aortic arch. This study sought to clarify early outcomes of the procedure and verify its haemodynamic advantages using computational fluid dynamics (CFD). METHODS Fourteen consecutive patients with hypoplastic left heart syndrome or a variant who underwent chimney reconstruction in the Norwood procedure between January 2013 and March 2018 were enrolled. Median age and body weight at the time of operation were 2.5 months and 4.1 kg, respectively. Thirteen patients (93.9%) had been palliated with previous bilateral pulmonary artery (PA) banding. In addition, patient-specific CFD models of neoarches based on postoperative computed tomograms from 6 patients were created and the flow profiles analysed. RESULTS Survival rates at 1, 3 and 5 years were 76.6%, 67.3% and 67.3%, respectively. No patient developed left PA compression by neoaorta, neoaortic dilation or neoaortic insufficiency. Only 2 patients (14.3%) required surgical intervention for recoarctation. Fontan completion was performed on 5 patients. On CFD analysis, all reconstructed aortic arches showed low energy loss (9.16–14.4 mW/m2) and low wall shear stresses. CONCLUSIONS Chimney reconstruction was a feasible technique when homografts were not readily available. CFD analyses underscored the fact that this technique produced excellent flow profiles. Larger studies should be conducted to clarify long-term outcomes.

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Jung, E. M., F. Jung, C. Stroszczynski et I. Wiesinger. « Dynamic endoluminal contrast enhanced ultrasound (CEUS) for display of drainages in inflammatory abdominal fluid collections1 ». Clinical Hemorheology and Microcirculation 80, n^o 2 (17 février 2022) : 49–59. http://dx.doi.org/10.3233/ch-211370.

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AIM: To evaluate the additive clinical value of endoluminal contrast enhanced ultrasound (CEUS) after interventional placement of drainages in abdominal fluid collections. MATERIAL/METHOD: Examination of 30 patients using a 1–6 MHz convex probe (Resona 7, Mindray) to locate the fluid collection in B-Mode. Additionally, dynamic endoluminal CEUS with 1 ml sulphur-hexafluoride microbubbles was performed to measure the extent of the percutaneously drained abscesses. Independent assessment of dynamically stored images in PACS in DICOM format. Correlation to reference imaging using computed tomography (CT). RESULTS: A total of 30 patients were examined (17 m, 19–78 years, mean 56.1 years). Drainages were positioned in the liver in 15 cases, in the pelvis after kidney transplantation in 4 cases, close to the spleen in 1 case, and in the abdomen in 10 cases. In all cases abscesses showed marginal hyperaemia with reactive septations in CEUS. The drainage position was assessed by means of B-mode in all cases first and then by CEUS. In 4 cases CEUS showed a fistula to the pleura, in 5 cases to the peritoneum, in 2 cases to the intestine, in 5 cases to the biliary tract, corresponding to the CT. In 2 cases there was a hint of an anastomotic leakage after intestinal anastomosis, which was reliably detected by CT. The drainage was removed in 11 cases within a period of 2 to 5 days after CEUS control, in 9 cases within a period of 5 to 10 days. Another operation was necessary in 3 cases. A new drainage was placed in 2 cases. The required amount of ultrasound contrast medium is 1 ml endoluminally diluted to 9 ml sodium chloride. CONCLUSION: CEUS facilitates the exact localization and characterization of inflammatory abdominal fluid collections. Furthermore, possible fistulas can be detected that cannot be seen with conventional ultrasound.

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Yu, Yue, David Kamensky, Ming-Chen Hsu, Xin Yang Lu, Yuri Bazilevs et Thomas J. R. Hughes. « Error estimates for projection-based dynamic augmented Lagrangian boundary condition enforcement, with application to fluid–structure interaction ». Mathematical Models and Methods in Applied Sciences 28, n^o 12 (novembre 2018) : 2457–509. http://dx.doi.org/10.1142/s0218202518500537.

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In this work, we analyze the convergence of the recent numerical method for enforcing fluid–structure interaction (FSI) kinematic constraints in the immersogeometric framework for cardiovascular FSI. In the immersogeometric framework, the structure is modeled as a thin shell, and its influence on the fluid subproblem is imposed as a forcing term. This force has the interpretation of a Lagrange multiplier field supplemented by penalty forces, in an augmented Lagrangian formulation of the FSI kinematic constraints. Because of the non-matching fluid and structure discretizations used, no discrete inf-sup condition can be assumed. To avoid solving (potentially unstable) discrete saddle point problems, the penalty forces are treated implicitly and the multiplier field is updated explicitly. In the present contribution, we introduce the term dynamic augmented Lagrangian (DAL) to describe this time integration scheme. Moreover, to improve the stability and conservation of the DAL method, in a recently-proposed extension we projected the multiplier onto a coarser space and introduced the projection-based DAL method. In this paper, we formulate this projection-based DAL algorithm for a linearized parabolic model problem in a domain with an immersed Lipschitz surface, analyze the regularity of solutions to this problem, and provide error estimates for the projection-based DAL method in both the [Formula: see text] and [Formula: see text] norms. Numerical experiments indicate that the derived estimates are sharp and that the results of the model problem analysis can be extrapolated to the setting of nonlinear FSI, for which the numerical method was originally proposed.

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Amir, Offer, Stefan D. Anker, Ittamar Gork, William T. Abraham, Sean P. Pinney, Daniel Burkhoff, Ilan D. Shallom, Ronit Haviv, Elazer R. Edelman et Chaim Lotan. « Feasibility of remote speech analysis in evaluation of dynamic fluid overload in heart failure patients undergoing haemodialysis treatment ». ESC Heart Failure 8, n^o 4 (5 mai 2021) : 2467–72. http://dx.doi.org/10.1002/ehf2.13367.

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Ganushchak, Yuri M., Eva R. Kurniawati, Jos G. Maessen et Patrick W. Weerwind. « Peripheral cannulae selection for veno-arterial extracorporeal life support : a paradox ». Perfusion 35, n^o 4 (10 novembre 2019) : 331–37. http://dx.doi.org/10.1177/0267659119885586.

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Explosive penetration of veno-arterial extracorporeal life support in everyday practice has drawn awareness to complications of peripheral cannulation, resulting in recommendations to use smaller size cannulae. However, using smaller cannulae may limit the effectiveness of extracorporeal support and thereby the specific needs of the patient. Selection of proper size cannulae may therefore pose a dilemma, especially since pressure-flow characteristics at different hematocrits are lacking. This study evaluates the precision of cannula pressure drop prediction with increase of fluid viscosity from water flow-pressure charts by M-number, dynamic similarity law, and via fitted parabolic equation. Thirteen commercially available peripheral cannulae were used in this in vitro study. Pressure drop and flow were recorded using water and a water-glycerol solution as a surrogate for blood, at ambient temperature. Subsequently, pressure-flow curves were modeled with increased fluid viscosity (0.0031 N s m−2), and then compared by M-number, dynamic similarity law, and fitted parabolic equation. The agreement of predicted and measured values were significantly higher when the M-number (concordance correlation = 0.948), and the dynamic similarity law method (concordance correlation = 0.947) was used in comparison to the fitted parabolic equation (concordance correlation = 0.898, p < 0.01). The M-number and dynamic similarity based model allow for reliable prediction of peripheral cannula pressure drop with changes of fluid viscosity and could therefore aid in well-thought-out selection of cannulae for extracorporeal life support.

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Chandra, Ankur, Doran Mix et Nicole Varble. « Hemodynamic study of arteriovenous fistulas for hemodialysis access ». Vascular 21, n^o 1 (26 octobre 2012) : 54–62. http://dx.doi.org/10.1258/vasc.2011.201204.

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Dialysis access failure and associated complications represent a major cause of morbidity in patients with renal failure. This is due to an incomplete understanding of the hemodynamics associated with both arteriovenous fistula (AVF) successes and complications. Several decades of research have been performed studying these complex hemodynamic changes. This review provides an overview of work undertaken in three key areas of AVF hemodynamic research: mathematical modeling, in vivo fluid dynamic measurements and in vitro fluid dynamic modeling. Current and future work is then summarized involving the application of a comprehensive, systematic study of dialysis access hemodynamics. The ultimate goal is the ability to predict clinical outcomes of dialysis access procedures through personalized, patient-specific surgical planning. If successful, this type of tool would allow surgeons to predict multiple-dialysis access intervention outcomes and choose a personalized approach to maximize success.

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Heim, Laurant, Robert J. Poole, Richard Warwick et Michael Poullis. « The concept of aortic replacement based on computational fluid dynamic analysis : patient-directed aortic replacement† ». Interactive CardioVascular and Thoracic Surgery 16, n^o 5 (13 février 2013) : 583–88. http://dx.doi.org/10.1093/icvts/ivt031.

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Matsuura, Kaoru, Wei Wei Jin, Hao Liu et Goro Matsumiya. « Computational fluid dynamic study of multiple sequential coronary artery bypass anastomoses in a native coronary stenosis model ». Coronary Artery Disease 31, n^o 5 (20 mars 2020) : 458–63. http://dx.doi.org/10.1097/mca.0000000000000864.

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Maaliki, Naji, Michael Omar, Aleem Azal Ali, Amy Roemer, Jose Ruiz et Edin Sadic. « Myocardial Bridging Unmasks as an Acute Coronary Syndrome from Dehydration ». Case Reports in Cardiology 2021 (12 juillet 2021) : 1–4. http://dx.doi.org/10.1155/2021/5589776.

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A 50-year-old male presented for loss of consciousness. He was initially treated with intravenous epinephrine and fluids, and an electrocardiogram (ECG) displayed an ST-segment elevation in lead aVR with global ST-segment depressions. A subsequent left heart catheterization revealed that the middle segment of the left anterior descending artery (LAD) demonstrated severe stenosis during systole but would become patent during diastole, which was suggestive of myocardial bridging. After stopping the epinephrine and increasing the fluid infusion, the ECG changes rapidly resolved. The patient had later admitted to significant dehydration all day. Myocardial bridging is a congenital anomaly in which a coronary artery segment courses through the myocardium instead of the usual epicardial surface. Occasionally, myocardial bridging may present similarly to acute coronary syndrome in severe dehydration or hyperadrenergic states. The diagnosis can be made through coronary angiography, which reveals a dynamic vessel obstruction pattern corresponding with the cardiac cycle. Long-term effects may also include accelerated atherosclerosis. Treatment consists of reversing precipitating causes during acute presentations and decreasing the risk of coronary artery disease on a chronic basis.

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Moosavi, Mir-Hossein, Nasser Fatouraee, Hamid Katoozian, Ali Pashaei et Alejandro F. Frangi. « USING ATLAS OF HEART SHAPES FOR SIMULATION OF BLOOD FLOW IN LEFT VENTRICLE ». Biomedical Engineering : Applications, Basis and Communications 25, n^o 06 (décembre 2013) : 1350050. http://dx.doi.org/10.4015/s1016237213500506.

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Integrative modeling of cardiac system is important for understanding the complex biophysical function of the heart]. To this end, multimodal cardiovascular imaging plays an important role in providing the computational domain, the boundary/initial conditions, and tissue function and properties. In particular, the incorporation of blood flow in the physiological models can help to simulate the hemodynamic properties and their effects on cardiac function. In this paper, we present a multimodal framework for quantitative and subject-specific analysis of blood flow in the cardiac chambers, including the left ventricle (LV). The 3D geometries of the LV at different time steps are extracted from medical images using an atlas of LV shape. The motion of the myocardium wall is used to extract the moving boundary data of the computational geometry. The data is used as a constraint for the computational fluid dynamics (CFD). An arbitrary Lagrangian–Eulerian (ALE) finite element method (FEM) formulation is used to derive a numerical solution of the transient dynamic equation of the fluid domain. With this method, simulation results describe detailed flow characteristics (such as velocity, pressure and wall shear stress) in the computational domain. The personalized hemodynamic characteristics obtained with the proposed approach can provide clinical value for diagnosis and treatment of abnormalities related to disturbed blood flow such as in myocardial remodeling and aortic sinus lesion formation.

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