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Regular aerobic exercise (RAEX) elicits several positive adaptations in all organs and tissues of the body, culminating in improved health and well-being. Indeed, in over half a century, many studies have shown the benefit of RAEX on cardiovascular outcome in terms of morbidity and mortality. RAEX elicits a wide range of functional and structural adaptations in the heart and its coronary circulation, all of which are to maintain optimal myocardial oxygen and nutritional supply during increased demand. Although there is no evidence suggesting that oxidative metabolism is limited by coronary blood flow (CBF) rate in the normal heart even during maximal exercise, increased CBF and capillary exchange capacities have been reported. Adaptations of coronary macro- and microvessels include outward remodelling of epicardial coronary arteries, increased coronary arteriolar size and density, and increased capillary surface area. In addition, there are adjustments in the neural and endothelial regulation of coronary macrovascular tone. Similarly, there are several adaptations at the level of microcirculation, including enhanced (such as nitric oxide mediated) smooth muscle-dependent pressure-induced myogenic constriction and upregulated endothelium-dependent/shear-stress-induced dilation, increasing the range of diameter change. Alterations in the signalling interaction between coronary vessels and cardiac metabolism have also been described. At the molecular and cellular level, ion channels are key players in the local coronary vascular adaptations to RAEX, with enhanced activation of influx of Ca2+ contributing to the increased myogenic tone (via voltage-gated Ca2+ channels) as well as the enhanced endothelium-dependent dilation (via TRPV4 channels). Finally, RAEX elicits a number of beneficial effects on several haemorheological variables that may further improve CBF and myocardial oxygen delivery and nutrient exchange in the microcirculation by stabilizing and extending the range and further optimizing the regulation of myocardial blood flow during exercise. These adaptations also act to prevent and/or delay the development of coronary and cardiac diseases., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

This paper is intended to update the former consensus between the French Societies of Radiology and Cardiology about the use of stress cardiac magnetic resonance imaging in chronic coronary syndrome, published in 2009. The Delphi method was used to build the present consensus. This expert panel consensus includes recommendations for indications, the procedure (with patient preparation), stress-inducing drugs, the acquisition protocol, interpretation and risk stratification by stress magnetic resonance imaging., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

The governing international standard for the development of prosthetic heart valves is International Organization for Standardization (ISO) 5840. This standard requires the assessment of the thrombus potential of transcatheter heart valve substitutes using an integrated thrombus evaluation. Besides experimental flow field assessment and ex vivo flow testing, computational fluid dynamics is a critical component of this integrated approach. This position paper is intended to provide and discuss best practices for the setup of a computational model, numerical solving, post-processing, data evaluation and reporting, as it relates to transcatheter heart valve substitutes. This paper is not intended to be a review of current computational technology; instead, it represents the position of the ISO working group consisting of experts from academia and industry with regards to considerations for computational fluid dynamic assessment of transcatheter heart valve substitutes.

Heart failure (HF) is a complex clinical syndrome with multiple interactions between the failing myocardium and cerebral (dys-)functions. Bi-directional feedback interactions between the heart and the brain are inherent in the pathophysiology of HF: (i) the impaired cardiac function affects cerebral structure and functional capacity, and (ii) neuronal signals impact on the cardiovascular continuum. These interactions contribute to the symptomatic presentation of HF patients and affect many co-morbidities of HF. Moreover, neuro-cardiac feedback signals significantly promote aggravation and further progression of HF and are causal in the poor prognosis of HF. The diversity and complexity of heart and brain interactions make it difficult to develop a comprehensive overview. In this paper a systematic approach is proposed to develop a comprehensive atlas of related conditions, signals and disease mechanisms of the interactions between the heart and the brain in HF. The proposed taxonomy is based on pathophysiological principles. Impaired perfusion of the brain may represent one major category, with acute (cardio-embolic) or chronic (haemodynamic failure) low perfusion being sub-categories with mostly different consequences (i.e. ischaemic stroke or cognitive impairment, respectively). Further categories include impairment of higher cortical function (mood, cognition), of brain stem function (sympathetic over-activation, neuro-cardiac reflexes). Treatment-related interactions could be categorized as medical, interventional and device-related interactions. Also interactions due to specific diseases are categorized. A methodical approach to categorize the interdependency of heart and brain may help to integrate individual research areas into an overall picture., (© 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.)

Reflexology is a complex massage intervention, based on the concept that specific areas of the feet (reflex points) correspond to individual internal organs within the body. Reflexologists trained in the popular Ingham reflexology method claim that massage to these points, using massage techniques unique to reflexology, stimulates an increase in blood supply to the corresponding organ. Reflexology researchers face two key methodological challenges that need to be addressed if a specific treatment-related hemodynamic effect is to be scientifically demonstrated. The first is the problem of inconsistent reflexology foot maps; the second is the issue of poor experimental controls. This article proposes a potential experimental solution that we believe can address both methodological challenges and in doing so, allow any specific hemodynamic treatment effect unique to reflexology to experimentally reveal itself.

The opening and closing dynamics of the aortic valve (AV) has a strong influence on haemodynamics in the aortic root, and both play a pivotal role in maintaining normal physiological functions of the valve. The aim of this study was to establish a subject-specific fluid-structure interaction (FSI) workflow capable of simulating the motion of a tricuspid healthy valve and the surrounding haemodynamics under physiologically realistic conditions. A subject-specific aortic root was reconstructed from magnetic resonance (MR) images acquired from a healthy volunteer, whilst the valve leaflets were built using a parametric model fitted to the subject-specific aortic root geometry. The material behaviour of the leaflets was described using the isotropic hyperelastic Ogden model, and subject-specific boundary conditions were derived from 4D-flow MR imaging (4D-MRI). Strongly coupled FSI simulations were performed using a finite volume-based boundary conforming method implemented in FlowVision. Our FSI model was able to simulate the opening and closing of the AV throughout the entire cardiac cycle. Comparisons of simulation results with 4D-MRI showed a good agreement in key haemodynamic parameters, with stroke volume differing by 7.5% and the maximum jet velocity differing by less than 1%. Detailed analysis of wall shear stress (WSS) on the leaflets revealed much higher WSS on the ventricular side than the aortic side and different spatial patterns amongst the three leaflets., (© 2024 The Author(s). International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd.)

Background: Cirrhosis patients often exhibit clinical symptoms such as right liver atrophy, portal hypertension, spleen enlargement and increased blood supply, which exhibit considerable variation between the left and right liver sections. These differences are hypothesized to stem from disparities in blood flow within the left and right portal vein (PV) branches. However, rigorous quantitative evidence remains scarce., Purpose: We mainly aim at quantitatively revealing the relationship between the blood flow rates of two PV branches and liver volumes, and providing quantitative evidence and theoretical support for the diagnosis and treatment of cirrhosis from the perspective of hemodynamics., Methods: Five cirrhotic patients and two healthy volunteers from Beijing Friendship Hospital are investigated. Their PV blood flow models are established based on computed tomography (CT) images and finite volume simulations. The volume of the left and right liver lobes are measured in 3-matic. The distributions of blood source in the PV branches are tracked by streamline analysis. The blood flow rates are quantitatively counted by integrating the blood source velocities. Linear analysis is performed to build the relationship between liver volumes and PV blood flow distributions., Results: Streamline analysis reveals significant differences in blood distribution between the left and right PV branches. The majority of blood from the superior mesenteric vein (SMV) flowed into the right portal vein (RPV), while most blood from the splenic vein (SV) entered the left portal vein (LPV). The main PV pressure drop linearly increases with the SV blood velocity for all PV structures of patients and healthy volunteers. The flow rate ratio Q RPV /Q LPV demonstrates an increase in tandem with the volume ratio V R /V L , exhibiting a linear correlation with the Pearson correlation coefficient being 0.93., Conclusion: The differences in the blood distributions are consistent with the clinicians' knowledge and validate our simulations. We demonstrated a linear increase in PV pressure with elevated SV blood velocity. Additionally, the volumes of the left and right hepatic lobes exhibited a positive correlation with blood flow rates in the corresponding PV branches., (© 2024 American Association of Physicists in Medicine.)

One-dimensional (1D) cardiovascular models offer a non-invasive method to answer medical questions, including predictions of wave-reflection, shear stress, functional flow reserve, vascular resistance and compliance. This model type can predict patient-specific outcomes by solving 1D fluid dynamics equations in geometric networks extracted from medical images. However, the inherent uncertainty in in vivo imaging introduces variability in network size and vessel dimensions, affecting haemodynamic predictions. Understanding the influence of variation in image-derived properties is essential to assess the fidelity of model predictions. Numerous programs exist to render three-dimensional surfaces and construct vessel centrelines. Still, there is no exact way to generate vascular trees from the centrelines while accounting for uncertainty in data. This study introduces an innovative framework employing statistical change point analysis to generate labelled trees that encode vessel dimensions and their associated uncertainty from medical images. To test this framework, we explore the impact of uncertainty in 1D haemodynamic predictions in a systemic and pulmonary arterial network. Simulations explore haemodynamic variations resulting from changes in vessel dimensions and segmentation; the latter is achieved by analysing multiple segmentations of the same images. Results demonstrate the importance of accurately defining vessel radii and lengths when generating high-fidelity patient-specific haemodynamics models. KEY POINTS: This study introduces novel algorithms for generating labelled directed trees from medical images, focusing on accurate junction node placement and radius extraction using change points to provide haemodynamic predictions with uncertainty within expected measurement error. Geometric features, such as vessel dimension (length and radius) and network size, significantly impact pressure and flow predictions in both pulmonary and aortic arterial networks. Standardizing networks to a consistent number of vessels is crucial for meaningful comparisons and decreases haemodynamic uncertainty. Change points are valuable to understanding structural transitions in vascular data, providing an automated and efficient way to detect shifts in vessel characteristics and ensure reliable extraction of representative vessel radii., (© 2024 The Author(s). The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Capillary Refill Time (CRT) assesses peripheral perfusion in resource-limited settings. However, the repeatability and reproducibility of CRT measurements are limited for individuals with darker skin. This paper presents quantitative CRT measurements demonstrating good performance and repeatability across all Fitzpatrick skin phototypes. The study involved 22 volunteers and utilized controlled compression at 7 kPa, an RGB video camera, and cocircular polarized white LED light. CRT was determined by calculating the time constant of an exponential regression applied to the mean pixel intensity of the green (G) channel. An adaptive algorithm identifies the optimal regression region for noise reduction, and flags inappropriate readings. The results indicate that 80% of the CRT readings fell within a 20% range of the expected CRT value. The repetition standard deviation was 17%. These findings suggest the potential for developing reliable and reproducible quantitative CRT methods for robust measurements in patient triage, monitoring, and telehealth applications., (© 2023 Wiley-VCH GmbH.)

In this work, we develop numerical methods for the solution of blood flow and coagulation on dynamic adaptive moving meshes. We consider the blood flow as a flow of incompressible Newtonian fluid governed by the Navier-Stokes equations. The blood coagulation is introduced through the additional Darcy term, with a permeability coefficient dependent on reactions. To this end, we introduce moving mesh collocated finite-volume methods for the Navier-Stokes equations, advection-diffusion equations, and a method for the stiff cascade of reactions. A monolithic nonlinear system is solved to advance the solution in time. The finite volume method for the Navier-Stokes equations features collocated arrangement of pressure and velocity unknowns and a coupled momentum and mass flux. The method is conservative and inf-sup stable despite the saddle point nature of the system. It is verified on a series of analytical problems and applied to the blood flow problem in the deforming domain of the right ventricle, reconstructed from a time series of computed tomography scans. At last, we demonstrate the ability to model the coagulation process in deforming microfluidic capillaries., (© 2023 John Wiley & Sons Ltd.)

The indices of asymmetry of microcirculation in the skin of the temporal areas of the head in young male and female subjects were studied. In 20 healthy volunteers (10 men and 10 women, age 18-19 years), synchronous measurements of the microcirculation of the skin of the symmetrical temporal areas of the head were carried out by laser Doppler flowmetry. The coefficients of asymmetry of regression relationships between perfusion changes in each side and initial perfusion values in both the same and opposite sides, the distribution function of perfusion asymmetry coefficients, and variability of perfusion in the studied areas were analyzed. The sex differences of the measured characteristics of asymmetry were revealed. In men, the distribution functions of perfusion asymmetry are pointed, with positive excesses, and in women they were flat, with negative excesses. In female subjects, the contribution of the right microcirculatory bed to the right-left hemodynamic balance was higher. These findings support the hypothesis on greater plasticity of the female brain in comparison with the male brain., (© 2023. Springer Science+Business Media, LLC, part of Springer Nature.)

Numerical simulations of cardiac blood pump systems are integral to the optimization of device design, hydraulic performance and hemocompatibility. In wave membrane blood pumps, blood propulsion arises from the wave propagation along an oscillating immersed membrane, which generates small pockets of fluid that are pushed towards the outlet against an adverse pressure gradient. We studied the Fluid-Structure Interaction between the oscillating membrane and the blood flow via three-dimensional simulations using the Extended Finite Element Method (XFEM), an unfitted numerical technique that avoids remeshing by using a fluid fixed mesh. Our three-dimensional numerical simulations in a realistic pump geometry highlighted, for the first time in this field of application, that XFEM is a reliable strategy to handle complex industrial problems. Moreover, they showed the role of the membrane deformation in promoting a blood flow towards the outlet despite an adverse pressure gradient. We also simulated the pump system at different pressure conditions and we validated the numerical results against in-vitro experimental data., (© 2021 John Wiley & Sons Ltd.)

Despite a large body of evidence, the implementation of guidelines on hemodynamic optimization and goal-directed therapy remains limited in daily routine practice. To facilitate/accelerate this implementation, a panel of experts in the field proposes an approach based on six relevant questions/answers that are frequently mentioned by clinicians, using a critical appraisal of the literature and a modified Delphi process. The mean arterial pressure is a major determinant of organ perfusion, so that the authors unanimously recommend not to tolerate absolute values below 65 mmHg during surgery to reduce the risk of postoperative organ dysfunction. Despite well-identified limitations, the authors unanimously propose the use of dynamic indices to rationalize fluid therapy in a large number of patients undergoing non-cardiac surgery, pending the implementation of a "validity criteria checklist" before applying volume expansion. The authors recommend with a good agreement mini- or non-invasive stroke volume/cardiac output monitoring in moderate to high-risk surgical patients to optimize fluid therapy on an individual basis and avoid volume overload. The authors propose to use fluids and vasoconstrictors in combination to achieve optimal blood flow and maintain perfusion pressure above the thresholds considered at risk. Although purchase of disposable sensors and stand-alone monitors will result in additional costs, the authors unanimously acknowledge that there are data strongly suggesting this may be counterbalanced by a sustained reduction in postoperative morbidity and hospital lengths of stay. Beside existing guidelines, knowledge and explicit clinical reasoning tools followed by decision algorithms are mandatory to implement individualized hemodynamic optimization strategies and reduce postoperative morbidity and duration of hospital stay in high-risk surgical patients. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the estimates of pump flow and systemic vascular resistance (SVR) derived from a mathematical regression model to those from an artificial deep neural network (ADNN). Hemodynamic and pump-related data were generated using both the Cleveland Clinic continuous-flow total artificial heart (CFTAH) and pediatric CFTAH on a mock circulatory loop. An ADNN was trained with generated data, and a mathematical regression model was also generated using the same data. Finally, the absolute error for the actual measured data and each set of estimated data were compared. A strong correlation was observed between the measured flow and the estimated flow using either method (mathematical, R = 0.97, p < 0.01; ADNN, R = 0.99, p < 0.01). The absolute error was smaller in the ADNN estimation (mathematical, 0.3 L/min; ADNN 0.12 L/min; p < 0.01). Furthermore, strong correlation was observed between measured and estimated SVR (mathematical, R = 0.97, p < 0.01; ADNN, R = 0.99, p < 0.01). The absolute error for ADNN estimation was also smaller than that of the mathematical estimation (mathematical, 463 dynes·sec·cm -5 ; ADNN, 123 dynes·sec·cm -5 , p < 0.01). Therefore, in this study, ADNN estimation was more accurate than mathematical regression estimation. http://links.lww.com/ASAIO/A991., Competing Interests: Disclosure: B.D.K., J.H.K., and K.F. are co-inventors of Cleveland Clinic’s continuous-flow total artificial heart (CFTAH) and pediatric continuous-flow total artificial heart (P-CFTAH). The CFTAH and P-CFTAH technology is owned by Cleveland Clinic. The remaining authors declare that they have no conflicts of interest., (Copyright © ASAIO 2023.)

Purpose: To investigate the feasibility of high-frame-rate vector flow imaging (HiFR-VFI) compared to ultrasound color Doppler flow imaging (CDFI) for precisely evaluating flow characteristics in the carotid bifurcation (CB) of presumed healthy adults., Methods: Forty-three volunteers were assessed for flow characteristics and their extensions using HiFR-VFI and CDFI in CBs. The flow patterns were classified according to the streamlines in HiFR-VFI and quantitatively measured using an innovative turbulence index (Tur-value). Interobserver agreement was also assessed., Results: HiFR-VFI was consistent with CDFI in detecting laminar and nonlaminar flow in 81.4% of the cases; however, in 18.6% of the cases, only HiFR-VFI identified the nonlaminar flow. HiFR-VFI showed a larger extension of complex flow (0.37 ± 0.26 cm 2 ) compared to CDFI (0.22 ± 0.21 cm 2 ; p < 0.05). The flow patterns were classified into four types: 3 type-I (laminar flow), 35 type-II (rotational flow), 27 type-III (reversed flow), and 5 type-IV (complex flow). The Tur-value of type-IV (50.03 ± 14.97)% is larger than type-III (44.57 ± 8.89)%, type-II (16.30 ± 8.16)%, and type-I (1.48 ± 1.43)% (p < 0.05). Two radiologists demonstrated almost perfect interobserver agreement on recognizing the change of streamlines (κ = 0.81, p < 0.001). The intraclass correlation coefficient of the Tur-value was 0.98., Conclusion: HiFR-VFI can reliably characterize complex hemodynamics with quantitative turbulence measurement and may be an auxiliary diagnostic tool for assessing atherosclerotic arterial disease., (© 2023 Wiley Periodicals LLC.)

In this work, we introduce an algorithmic approach to generate microvascular networks starting from larger vessels that can be reconstructed without noticeable segmentation errors. Contrary to larger vessels, the reconstruction of fine-scale components of microvascular networks shows significant segmentation errors, and an accurate mapping is time and cost intense. Thus there is a need for fast and reliable reconstruction algorithms yielding surrogate networks having similar stochastic properties as the original ones. The microvascular networks are constructed in a marching way by adding vessels to the outlets of the vascular tree from the previous step. To optimise the structure of the vascular trees, we use Murray's law to determine the radii of the vessels and bifurcation angles. In each step, we compute the local gradient of the partial pressure of oxygen and adapt the orientation of the new vessels to this gradient. At the same time, we use the partial pressure of oxygen to check whether the considered tissue block is supplied sufficiently with oxygen. Computing the partial pressure of oxygen, we use a 3D-1D coupled model for blood flow and oxygen transport. To decrease the complexity of a fully coupled 3D model, we reduce the blood vessel network to a 1D graph structure and use a bi-directional coupling with the tissue which is described by a 3D homogeneous porous medium. The resulting surrogate networks are analysed with respect to morphological and physiological aspects., (© 2020 The Authors. International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd.)

Left ventricular assist devices (LVADs) have been used as a bridge to transplantation or as destination therapy to treat patients with heart failure (HF). The inability of control strategy to respond automatically to changes in hemodynamic conditions can impact the patients' quality of life. The developed control system/algorithm consists of a control system that harmoniously adjusts pump speed without additional sensors, considering the patient's clinical condition and his physical activity. The control system consists of three layers: (a) Actuator speed control; (b) LVAD flow control (FwC); and (c) Fuzzy control system (FzC), with the input variables: heart rate (HR), mean arterial pressure (MAP), minimum pump flow, level of physical activity (data from patient), and clinical condition (data from physician, INTERMACS profile). FzC output is the set point for the second LVAD control schemer (FwC) which in turn adjusts the speed. Pump flow, MAP, and HR are estimated from actuator drive parameters (speed and power). Evaluation of control was performed using a centrifugal blood pump in a hybrid cardiovascular simulator, where the left heart function is the mechanical model and right heart function is the computational model. The control system was able to maintain MAP and cardiac output in the physiological level, even under variation of EF. Apart from this, also the rotational pump speed is adjusted following the simulated clinical condition. No backflow from the aorta in the ventricle occurred through LVAD during tests. The control algorithm results were considered satisfactory for simulations, but it still should be confirmed during in vivo tests., (© 2020 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

: Improvement in hemodynamic parameters is routinely demonstrated in patients implanted with continuous-flow left ventricular assist devices (CF-LVADs). However, functional capacity assessed by cardiopulmonary exercise test (CPET), following LVAD implantation, remains considerably restricted. In this review, we analyzed the current knowledge on the causes of the persistent limitation in exercise capacity in CF-LVAD patients. Limitation to exercise is multifactorial and involves: LVAD factors (fixed CF-LVAD pump speed), native cardiac factors (residual function of native left ventricle, right ventricular dysfunction, aortic valve abnormalities), comorbidities (abnormal skeletal muscle metabolism, low skeletal muscle mass, anemia), patient's characteristics (age, physical deconditioning). In addition, we emphasize the role of some potential therapeutic strategies like the increase in CF-LVAD pump speed according to the patient's activity, the echo-optimization of the device (paying attention to right ventricular function and aortic valve opening), the implementation of physical rehabilitation and the treatment of potentially reversible extracardiac factors (anemia, muscle deconditioning, obesity).

Interest in developing paper-based devices for point-of-care diagnostics in resource-limited settings has risen remarkably in recent decades. In this paper, we demonstrate what we refer to as “high yield passive rrythrocyte removal” (HYPER) technology, which utilizes capillary forces in a unique cross-flow filtration for the separation of whole blood with performance comparable to centrifuges. As we will demonstrate, state-of-the-art passive blood separation methods implemented in paper-based systems exhibit rapid blood cell clogging on the filtration media or serum outlet and yield only about 10–30% of the total serum present in the sample. Our innovation results from the inclusion of a differentiation pad, which exploits hydrodynamic effects to reduce the formation of a fouling layer on the blood filtration membrane resulting in more than 60% serum yield with undiluted whole blood as direct input. To demonstrate the effectiveness of the HYPER technology we implement it in a lateral flow system and demonstrate the accurate quantification of vitamin A and iron levels in whole blood samples in 15 minutes. [ABSTRACT FROM AUTHOR]

SUMMARY Digital books have become popular as electronic media has become more common. An evaluation that includes not only a subjective assessment of readability or usability, but also an objective assessment of psychometric health impact is needed. The goal of this study is an objective assessment of the physiological and psychological effects of reading books using electronic or paper media. This paper focuses on hemodynamic parameters. The measurement items include VAS and POMS as a psychological index and hemodynamic parameters as a physiological index. As a result, low levels of vigor and limited readability were recognized as significant ( p < 0.05) when reading a book using electronic media as compared to paper media. The cardiovascular system was actively engaged in coping because of sympathetic hyperactivity in the hemodynamic reaction. By contrast, using electronic media was not seen to involve stress coping. We also found that the parasympathetic nervous system activity was enhanced by the illegibility of sentences and fatigue due to using electronic media. Based on all of these results, we identified a difference in how people react physiologically when reading a book using electronic and paper media. [ABSTRACT FROM AUTHOR]

A numerical investigation of MHD blood flow through a stenosed permeable curved artery has been done in this study. Blood flow is considered in two-phases; core and plasma region, respectively. Viscosity of the core region is considered as temperature-dependent, while constant viscosity is considered in plasma region. The governing equations of the proposed two-phase blood flow model are considered in the toroidal coordinate system. The second-order finite difference method is adopted to solve governing equations with [Formula: see text] tolerance in the iteration process. A comparative study of Darcy number (Da) is performed to understand the influence of permeable and impermeable wall conditions. The effect of various physical parameters such as magnetic field (M), viscosity variation parameter ([Formula: see text]), Darcy number (Da), heat source (H) and chemical reaction parameter ([Formula: see text]) is displayed graphically on the flow velocity, temperature, concentration, wall shear stress and frictional resistance profiles. A comparison with published work has also been displayed through the graph to validate the present model, and it is in fair agreement with the existing work. The present study suggested that the curvature and permeability of the arterial wall raise the risk of atherosclerosis formation, while the implication of heat source on the blood flow lower this risk., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: The pre-hospital use of Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is increasing, although it remains controversial, in part because of suggested contraindications such as acute cardiac tamponade (ACT). As both the pre-hospital and in-hospital use of REBOA might potentially occur with concurrent ACT, knowledge of the hemodynamic effect of REBOA in this setting is crucial. This study, therefore, aimed at investigating the physiological effects of REBOA in hemodynamic instability secondary to ACT in a porcine model. We hypothesize that REBOA can temporarily increase systemic blood pressure and carotid blood flow, and prolong survival, in hemodynamic shock caused by ACT., Methods: Fourteen pigs (24-38 kg) underwent ACT, through true cardiac injury and hemorrhage into the pericardial space, and were allowed to hemodynamically deteriorate. At a systolic blood pressure (SBP) of 50 mm Hg (SBP50) they were randomized to total occlusion REBOA in zone 1 or to a control group. Survival, hemodynamic parameters, carotid blood flow (CBF), femoral blood flow (FBF), cardiac output (CO), end-tidal CO2, and arterial blood gas parameters were analyzed., Results: REBOA intervention was associated with a significant increase in SBP (50 mm Hg to 74 mm Hg, P = 0.016) and CBF (110 mL/min to 195 mL/min, P = 0.031), with no change in CO, compared to the control group. At 20 min after SBP50, the survival rate in the intervention group was 86% and in the control group 14%, with time to death being significantly longer in the intervention group., Conclusions: This randomized animal study demonstrates that REBOA can help provide hemodynamic stabilization and prolong survival in hemodynamic shock provoked by ACT. It is important to stress that our study does not change the fact that urgent pericardiocentesis or cardiac surgery is, and should remain, the standard optimal treatment for ACT.Level of evidence: Prospective, randomized, experimental animal study. Basic science study, therapeutic., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by the Shock Society.)

The liver is the most injured organ in abdominal trauma. Road traffic crashes and antisocial, violent behavior account for the majority of liver injuries. The present position paper represents the position of the World Society of Emergency Surgery (WSES) about the management of liver injuries. [ABSTRACT FROM AUTHOR]

Dexamethasone (DEX)-induced hypertension is observed in normotensive rats, but little is known about the effects of DEX on spontaneously hypertensive animals (SHR). This study aimed to evaluate the effects of DEX on hemodynamics, cardiac hypertrophy and arterial stiffness in normotensive and hypertensive rats. Wistar rats and SHR were treated with DEX (50 μg/kg s.c., 14 d) or saline. Pulse wave velocity (PWV), echocardiographic parameters, blood pressure (BP), autonomic modulation and histological analyses of heart and thoracic aorta were performed. SHR had higher BP compared with Wistar, associated with autonomic unbalance to the heart. Echocardiographic changes in SHR (vs. Wistar) were suggestive of cardiac remodeling: higher relative wall thickness (RWT, +28%) and left ventricle mass index (LVMI, +26%) and lower left ventricle systolic diameter (LVSD, -19%) and LV diastolic diameter (LVDD, -10%), with slightly systolic dysfunction and preserved diastolic dysfunction. Also, SHR had lower myocardial capillary density and similar collagen deposition area. PWV was higher in SHR due to higher aortic collagen deposition. DEX-treated Wistar rats presented higher BP (~23%) and autonomic unbalance. DEX did not change cardiac structure in Wistar, but PWV (+21%) and aortic collagen deposition area (+21%) were higher compared with control. On the other side, DEX did not change BP or autonomic balance to the heart in SHR, but reduced RWT and LV collagen deposition area (-12% vs. SHR CT ). In conclusion, the results suggest a differential effect of dexamethasone on arterial stiffness, myocardial remodeling and blood pressure between normotensive and spontaneously hypertensive rats., (© 2021 John Wiley & Sons, Ltd.)

Competing Interests: Dr. Joosten’s institution received funding from Edwards Lifesciences. Dr. Saugel received funding from Edwards Lifesciences, Pulsion Medical Systems SE, CNSystems Medizintechnik GmbH, Retia Medical LLC, Philips Medizin Systeme Böblingen GmbH, and Tensys Medical. Dr. Vincent has disclosed that he does not have any potential conflicts of interest.

Background/Aims: Modified rock, paper, scissors (RPS) tasks have previously been used in neuroscience to investigate activity of the prefrontal cortex (PFC). In this study, we investigated hemodynamic changes in the PFC using near-infrared spectroscopy (NIRS) during a modified RPS task in which each subject's successful performance rate was equalized; the workload was increased parametrically in order to reveal the resulting pattern of PFC activation. Methods: The subjects were 20 healthy adults. During RPS, the player uses hand gestures to represent rock, paper, and scissors. Rock beats scissors, paper beats rock, and scissors beats paper. In the modified RPS task, the player is instructed to lose intentionally against the computer hand; the computer goes first and the player follows. The interstimulus interval (ISI) level was adjusted with 11 steps. If the level rose, the ISI decreased and the workload increased parametrically. The maximal level (maxLv: the shortest ISI and the biggest workload) in which a subject could perform the task correctly was determined for every subject during rehearsal of the task prior to the experiment. Lowering the level from the maxLv made the task easier. Hemodynamic changes were measured by NIRS over 4 task levels (maxLv-3, maxLv-2, maxLv-1 and maxLv). Results: The hemodynamic changes in the left lateral PFC and bilateral Brodmann area 6 rose significantly with the increase in workload and presented a linear trend. Conclusion: These results suggest that PFC activation may linearly increase with increased workload during a modified RPS task in which successful performance rates of subjects are equalized. Copyright © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Aims: Resource optimization in the intensive cardiac care unit (ICCU) is, nowadays, of great importance because of the increasing number of acute cardiovascular patients requiring high-intensity level-of-care. Because of natural limits in ICCU bed availability, understanding, which patients will really benefit from in a such a critical care setting, is of paramount importance. In our study, we analysed a heterogeneous ICCU population with initially stable haemodynamic conditions, in order to find potential predictors of severe complications., Methods: Nine hundred and fifty patients admitted to our ICCU during the year 2019 were screened in order to detect those with a stable haemodynamic condition at admission. Data were extrapolated from an internal database. Comorbidity burden was expressed by the Charlson Comorbidity Index (CCI). Our primary end point was defined by a combination of severe complications requiring critical care, and in-hospital death., Results: Ninety-eight patients (14.1% of 695 stable patients identified) developed severe complications. After a multivariable logistic regression analysis, four predictors were identified: signs of congestive heart failure [OR: 9.25, 95% confidence interval (CI): 5.61-15.25; P < 0.001], SBP 120 mmHg or less (OR: 2.10, 95% CI: 1.27-3.47; P = 0.004), haemoglobin level 13 g/dl or less (OR: 1.75, 95% CI: 1.03-2.95; P = 0.037), and the CCI above 3 (OR: 2.27, 95% CI: 1.13-4.56; P = 0.022)., Conclusion: In our study, 73% of patients showed a stable haemodynamic condition on admission. Severe complications occurred in 14.1% of these patients, and signs of heart failure were the main determinants of the outcome. SBP, haemoglobin level, and the CCI concurred in the prediction of severe complications during the hospital stay., (Copyright © 2021 Italian Federation of Cardiology - I.F.C. All rights reserved.)

Purpose: Chemotherapy treatment can lead to cardiovascular toxicity and physical impairment prior to autologous hematopoietic stem cell transplantation (auto-HSCT). Cardiovascular adjustments during exercise and the exercise capacity remain unknown in patients prior to auto-HSCT. Thus, the hemodynamic responses during exercise and exercise capacity were evaluated using a novel effort test in patients prior to auto-HSCT., Methods: Thirty patients prior to auto-HSCT (BMT group: 44.6 ± 14.1 years) and 23 control participants (CON group: 43.9 ± 16.6 years) performed the 6-Minute Step Test (6MST) to assess their exercise capacity and the hemodynamic responses during exercise. Systolic and diastolic blood pressure (SBP and DBP), heart rate (HR), and oxygen saturation (SpO 2 ) were measured during the test. Rate-pressure product (RPP) was calculated multiplying SBP by HR. The highest HR value recorded during the test was compared with the maximum HR predicted by age and was used as % of maximum HR (%HRmax)., Results: The number of steps up and down performed by the BMT group was lower than CON (108.8 ± 25.3 vs. 127.5 ± 34.4 steps, P = 0.02). The BMT group showed a higher magnitude of increase in SBP and RPP during the 6MST when compared to CON (ΔSBP: 18.5 ± 11.45 vs. 8.30 ± 18.46 mmHg, P = 0.01; and ΔRPP: 8197.3 ± 3829.1 vs. 6170.9 ± 3568.9 mmHg beats min -1 , P = 0.05). The BMT group exhibited higher SpO2 and HR values throughout the protocol (P < 0.05), reaching a higher %HRmax than CON group (76.9 ± 9.6 vs. 66.4 ± 8.9%, P < 0.01)., Conclusions: Patients with indication for auto-HSCT have exacerbated chronotropic and pressor responses during exercise and reduced exercise capacity in the 6MST.

Background: Dobutamine is particularly suited to treatment of haemodynamic insufficiency caused by increased peripheral vascular resistance and myocardial dysfunction in the preterm infant. Knowledge of the elimination half-life is essential to estimate the steady state when its efficacy/safety can be evaluated., Methods: Analysis of pharmacokinetic data in ten preterm newborns treated with a new neonatal formulation of dobutamine (IMP) after screening for haemodynamic insufficiency within the first 72 h from birth. Blood samples were withdrawn at the end of IMP infusion and at a random time after the end of infusion (5 min, 15 min, 45 min, 2 h and 6 h). IMP concentration in each sample was measured by ultra-high performance liquid chromatography with electrochemical detection., Results: Median duration of IMP infusion was 37.7 h (IQR 21.2). Calculated IMP half-life ranged between 3.06 and 36.1 min (median 10.6 min), leading to a time to reach the steady-state concentration between 15 min and >2 h. Adverse events were not related to IMP., Conclusions: The wide variability in dobutamine metabolism in preterm infants requires awareness about the risk of under- or overtreatment. A delay of up to 3 h might be required before drawing blood samples to evaluate the effective dose., Impact: Small trials suggest dobutamine as the optimal drug in the preterm infant with haemodynamic insufficiency after birth. Age-related differences in drug pharmacokinetics may result in suboptimal treatments. The lack of formal studies in preterms results in inadequate data on efficacy and safety. This study provides data on the variability of the elimination half-life of dobutamine in the very preterm infant during transitional circulation. There is a wide variation in the time to reach the plasma concentration corresponding to steady state, the moment when its efficacy/safety can be reliably evaluated. This information is crucial for planning future trials on cardiovascular support.

The present contribution deals with the estimation of haemodynamics Quantities of Interest by exploiting Ultrasound Doppler measurements. A fast method is proposed, based on the Parameterized Background Data-Weak (PBDW) method. Several methodological contributions are described: a sub-manifold partitioning is introduced to improve the reduced-order approximation, two different ways to estimate the pressure drop are compared, and an error estimation is derived. A fully synthetic test-case on a realistic common carotid geometry is presented, showing that the proposed approach is promising in view of realistic applications., (© 2020 John Wiley & Sons, Ltd.)

The mechanisms of high blood pressure (HBP) -related brain pathology progression remain relatively unclear. We investigated whether lowering BP in chronic HBP patients normalizes cerebral perfusion dynamics at resistance vessel and capillary levels. Sixty-seven patients with HBP and 49 age- and sex-matched healthy controls underwent simultaneous recordings of middle cerebral artery blood flow velocity (CBFV), BP, and end-tidal CO 2 concentration. Thirty-four controls and 28 patients underwent additional near-infrared spectroscopy recordings (oxygenated [O 2 Hb] and deoxygenated [HHb] hemoglobin). Degree of microcirculatory white matter lesions was graded by Fazekas scale. Dynamic cerebral autoregulation (dCA) was assessed by transfer function analysis. BP was successfully lowered (patients = 89 ± 15 mm Hg, controls = 87 ± 17), but cerebrovascular resistance was higher in BP patients (p < 0.05). BP-CBFV phase was lower in very low frequency (VLF) (left/right: 48 ± 20°/44 ± 17; controls: 61 ± 20/60 ± 21; p < 0.001) and low frequency (LF) (34 ± 14/35 ± 14; controls: 48 ± 20/44 ± 17; p < 0.05) ranges. Gain was higher in VLF range (in %/ mm Hg 0.56 ± 0.44/0.59 ± 0.49; controls: 0.32 ± 0.29/0.34 ± 0.32; p ≤ 0.005). BP-CBFV phase and gain did not differ across Fazekas groups. Across all patients, the capillary phases and gains (CBFV-[O2Hb], CBFV-[HHb]) were comparable to controls. Successfully treated chronic HBP results in normal brain capillary hemodynamics while the resistance vessel state is disturbed (phase decrease, gain increase).

There is limited data available to guide management of patients supported with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). An international cross-sectional survey of medical directors/program coordinators from Extracorporeal Life Support Organization centers was conducted. A hierarchical clustering on principle components was used. A total of 243 (55%) centers responded and were divided into three clusters: Cluster 1 (n = 102) had few high volumes and low specialized heart failure (HF) involvement; Cluster 2 (n = 75) had few high volumes and moderate HF involvement; Cluster 3 (n = 66) contained the majority of centers with >50 annual cases and high HF involvement. The most divergent responses were observed between Clusters 1 and 3 wherein Cluster 1 centers were less likely to change management based on pulse pressure (77% vs. 100%; p < 0.001) and would rather avoid inotropes to "rest the heart" (28%). Cluster 3 centers were more likely to perform daily echocardiograms (50% vs. 24%, p < 0.001), which were less likely to be exclusively performed by cardiologist (36% vs. 58%, p < 0.046) and base weaning on echocardiographic findings, when compared to Cluster 1 (3.97/5 vs. 3.56, p < 0.001). Responses were variable in management reflecting the lack of evidence for hemodynamic care for those supported with VA-ECMO.

Purpose: Although the underlying mechanisms of reflex syncope remain under debate, there is evidence that it results from decreased cardiac output related to splanchnic blood pooling or a fall in systemic vascular resistance. The aim was to evaluate the response of cerebrovascular and autonomic variables to passive orthostatic challenge in adult patients with different mechanisms leading to reflex syncope., Methods: The study included 30 subjects (66% women, mean age 34 ± 14 years) who suffered a hemodynamic collapse during a drug-free head-up tilt test. They were categorized into three groups according to their hemodynamic cardiovascular response during the head-up tilt test: (1) reduced cardiac output (patients, n = 10), (2) reduced systemic vascular resistance (patients, n = 10), and (3) reduced cardiac output and systemic vascular resistance, (reduced cardiac output reduced systemic vascular resistance patients, n = 10). Cardiovascular and cerebrovascular dynamics, as well as autonomic variables, were noninvasively assessed during the head-up tilt test and median values were calculated at baseline and throughout the three phases of the tilt., Results: At baseline, the reduced systemic vascular resistance group had lower cardiac output and higher total peripheral resistance index and a sustained increase of heart rate throughout the head-up tilt test in comparison to the other groups. Cerebrovascular dynamics and autonomic variables showed no difference among groups throughout the test. Compared with baseline, these variables had similar percentual change during the orthostatic challenge., Conclusions: Although different cardiovascular hemodynamic mechanisms of reflex syncope exist in adult patients, cerebrovascular hypoperfusion and autonomic modulation occur to a similar extent.

Introduction: The management of liver failure (LF) remains a challenge for the physician. Therapeutic plasma exchange (TPE) improves consciousness level and tends to normalize hyperkinetic circulation by removing neurotoxic substances from the circulation. Hemodynamic stability is essential for optimal patient management. The objective of this study was to observe the effects of TPE on mean arterial pressure (MAP), vasopressor dependency index (VDI) and vasopressor score (VS) in LF patients., Method: This retrospective study was conducted on LF patients at a liver institute in Delhi. Clinical data were collected from April 2018 to September 2018., Results: A total of 229 TPEs were performed on 97 patients. Baseline values were MAP 82 (56-141), VS 10.55 (0.00-111.66), and VDI 0.13(0.00-1.44). MAP increased with TPE from 82 to 85 at 1 hour post-TPE and fell back to baseline in 6 hours post-TPE. VDI and VS decreased significantly with TPE till 1 hour post-TPE but reached baseline by 6 hours post-TPE. VDI decreased consistently untill third TPE session and remained stable thereafter. Post-TPE, S. Procalcitonin decreased from 4.69 to 4.25. The average time from admission to start of first TPE procedure was 11 hours in survivors and 26 hours in nonsurvivors., Conclusions: Patients became hemodynamically stable with TPE but effect did not last long. Sustained improvements in VDI were observed with multiple TPE procedures. Distinct differences were seen between survivors and nonsurvivors in MAP, VDI, and VS early initiation of TPE correlated with improved survival in ALF patients. TPE did not increase risk of sepsis., (© 2019 Wiley Periodicals, Inc.)

The central hemodynamic characteristics of young adults with isolated systolic hypertension (ISH) remain controversial, particularly regarding the extent of pulse pressure amplification (PPamp) compared with that of normotensives (NTs). Given the lack of ambulatory blood pressure monitoring (ABPM)-based data, this study evaluated 509 untreated young adults (18-35 years) who had undergone ABPM during the last decade, 109 who had undergone both ABPM and SphygmoCor analysis, and 26 newly recruited NTs. The agreement rate between office BP- and ABPM-based subtype classification was alarmingly low (50.7%). ISH was distinguishable from systolic-diastolic hypertension, the predominant subtype characterized by increased central BPs and stiffened arteries. The central hemodynamic parameters were all similar between patients with ISH and white-coat hypertension (WC). ISH patients had central BPs that were, albeit higher than those of NTs, at an upper-normal level that was comparable to those of WC patients. ISH patients had similar cfPWV but significantly higher PPamp than NTs (p = 0.032). The central hemodynamic parameters of the participants were further analyzed according to central pressure waveform types (A vs. B vs. C). Type C waves were associated with the highest PPamp and lowest cfPWV, whereas type A waves were associated with the lowest PPamp and highest cfPWV. Subjects with type B waves, an intermediate form, also had considerably high PPamps. Waveform composition differed significantly across hypertension subtypes (p < 0.001). ISH patients mostly had type B or C waves (96.7%), with only 3.3% having type A waves. This study based on a refined diagnosis showed that the ambulatory ISH of young adults arises from highly elastic arteries and related robustness of PPamp and shares similar central hemodynamic characteristics with WC patients.

Background and Aim: To mitigate the risk of perioperative neurological complications during frozen elephant trunk procedures, we aimed to computationally evaluate the effects of direct cerebral perfusion strategy through a left carotid-subclavian bypass on hemodynamics in a patient-specific thoracic aorta model., Methods: Between July 2016 and March 2019, 11 consecutive patients underwent frozen elephant trunk operation using the left carotid-subclavian bypass with a side graft anastomosis and right-axillary cannulation for systemic and brain perfusion. A multiscale model realized coupling three-dimensional computational fluid dynamics was developed and validated with in vivo data. Model comparison with direct antegrade cannulation of all epiaortic vessels was performed. Wall shear stress, wall shear stress spatial gradient, and localized normalized helicity were selected as hemodynamic indicators. Four cerebral perfusion flows were tested (6 to 15 mL/kg/min)., Results: Direct cerebral perfusion of the left subclavian bypass resulted in higher flow rates with augmented speeds in all epiaortic vessels in comparison with traditional perfusion model. At the level of the left vertebral artery (LVA), a speed of 22.5 vs 21 mL/min and mean velocity of 3.07 vs 2.93 cm/s were registered, respectively. With a cerebral perfusion flow of 15 mL/kg, lower LVA wall shear stress (1.596 vs 2.030 N/m 2 ), and wall shear stress gradient (1445 vs 5882 N/m 3 ) were observed. A less disturbed flow considering the localized normalized helicity was documented. No patients experienced neurological/spinal cord damages., Conclusions: Direct perfusion of a left carotid bypass proved to be cerebroprotective, resulting in a more physiological and stable anterior and posterior cerebral perfusion., (© 2020 Wiley Periodicals, Inc.)

Introduction: Vasovagal reflex is the most common type of syncope but its etiology is not fully elucidated. Venous return and cardiac output are key in hemodynamic control. The aim of the study was to assess cardiovascular biomarkers and echocardiographic measures at rest and during hypovolemia in women with and without a history of vasovagal syncope., Methods: Fourteen women (aged 18-30) suffering from recurrent vasovagal syncope and 15 age-matched healthy women were included. Graded lower body negative pressure (LBNP) was used to create central hypovolemic stress until signs of presyncope occurred. Echocardiography was applied at rest and throughout LBNP. Cardiovascular biomarkers: copeptin, mid-regional proadrenomedullin, mid-regional pro-ANP, C-terminal proendothelin-1, and plasma norepinephrine were measured both at rest and throughout graded hypovolemia to presyncope., Results: Women prone to vasovagal syncope presented with a narrower right ventricle (RV) (29 ± 1 vs 32 ± 1 mm, P < .05), smaller left atrium (36 ± 2 vs 47 ± 3 cm 3 , P < .01) and lower cardiac output at rest (3.1 ± 0.2 vs 3.7 ± 0.2 L/min, P < .05) and during graded hypovolemia (P < .05). Copeptin was elevated at rest (4.3 ± 0.8 vs 2.5 ± 0.2 pmol/L, P < .05) and increased more in women with vasovagal syncope during progression of LBNP (P < .01). At rest, lower C-terminal proendothelin-1 (35 ± 5 vs 46 ± 2 pmol/L, P < .05) and higher norepinephrine levels (1.1 ± 0.1 vs 0.8 ± 0.1 nmol/L, P < .01) were seen in women with vasovagal syncope., Conclusion: Women prone to vasovagal syncope demonstrate reduced cardiac preload, lower cardiac output, as well as increased release of vasopressin in rest and during hypovolemic challenge. The results emphasize the importance of venous return and cardiac output in the pathogenesis of vasovagal syncope., (© 2019 Wiley Periodicals, Inc.)