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Sample records for hemodynamic purposes oxymetry

  1. Hemodynamics.

    PubMed

    Secomb, Timothy W

    2016-04-01

    A review is presented of the physical principles governing the distribution of blood flow and blood pressure in the vascular system. The main factors involved are the pulsatile driving pressure generated by the heart, the flow characteristics of blood, and the geometric structure and mechanical properties of the vessels. The relationship between driving pressure and flow in a given vessel can be understood by considering the viscous and inertial forces acting on the blood. Depending on the vessel diameter and other physical parameters, a wide variety of flow phenomena can occur. In large arteries, the propagation of the pressure pulse depends on the elastic properties of the artery walls. In the microcirculation, the fact that blood is a suspension of cells strongly influences its flow properties and leads to a nonuniform distribution of hematocrit among microvessels. The forces acting on vessel walls include shear stress resulting from blood flow and circumferential stress resulting from blood pressure. Biological responses to these forces are important in the control of blood flow and the structural remodeling of vessels, and also play a role in major disease processes including hypertension and atherosclerosis. Consideration of hemodynamics is essential for a comprehensive understanding of the functioning of the circulatory system. PMID:27065172

  2. Hemodynamics of Cerebral Aneurysms

    PubMed Central

    Sforza, Daniel M.; Putman, Christopher M.; Cebral, Juan Raul

    2009-01-01

    The initiation and progression of cerebral aneurysms are degenerative processes of the arterial wall driven by a complex interaction of biological and hemodynamic factors. Endothelial cells on the artery wall respond physiologically to blood-flow patterns. In normal conditions, these responses are associated with nonpathological tissue remodeling and adaptation. The combination of abnormal blood patterns and genetics predisposition could lead to the pathological formation of aneurysms. Here, we review recent progress on the basic mechanisms of aneurysm formation and evolution, with a focus on the role of hemodynamic patterns. PMID:19784385

  3. Functional Hemodynamic Monitoring

    PubMed Central

    Pinsky, Michael R.

    2014-01-01

    Functional hemodynamic monitoring is the assessment of the dynamic interactions of hemodynamic variables in response to a defined perturbation. Dynamic tissue O2 saturation (StO2) responses to complete stop flow conditions (vascular occlusion test), which can be created by measuring hand StO2 and occluding flow with a blood pressure cuff, assesses cardiovascular sufficiency and microcirculatory blood flow distribution. Recent interest in functional hemodynamic monitoring for the bedside assessment of cardiovascular insufficiency has heightened with the documentation of its accuracy in predicting volume responsiveness using a wide variety of monitoring devices both invasive and non-invasive and across multiple patient groups and clinical conditions. Accordingly, fluid responsiveness can be predicted in a quantities fashion by measuring as arterial pulse pressure variation, left ventricular stroke volume variation or their surrogates during positive pressure breathing or the change in cardiac output response to a passive leg raising maneuver. However, volume responsiveness, though important, reflects only part of the overall spectrum of functional physiological variables that can be measured to define physiologic state and monitor response to therapy. PMID:25435480

  4. [Implantable hemodynamic monitoring devices].

    PubMed

    Seifert, M; Butter, C

    2015-11-01

    Heart failure is one of the most frequent diagnoses in hospital admissions in Germany. In the majority of these admissions acute decompensation of an already existing chronic heart failure is responsible. New mostly wireless and remote strategies for monitoring, titration, adaptation and optimization are the focus for improvement of the treatment of heart failure patients and the poor prognosis. The implantation of hemodynamic monitoring devices follows the hypothesis that significant changes in hemodynamic parameters occur before the occurrence of acute decompensation requiring readmission. Three different hemodynamic monitoring devices have so far been investigated in clinical trials employing right ventricular pressure, left atrial pressure and pulmonary artery pressure monitoring. Only one of these systems, the CardioMENS™ HF monitoring system, demonstrated a significant reduction of hospitalization due to heart failure over 6 months in the CHAMPION trial. The systematic adaptation of medication in the CHAMPION trial significantly differed from the usual care of the control arm over 6 months. This direct day to day management of diuretics is currently under intensive investigation; however, further studies demonstrating a positive effect on mortality are needed before translation of this approach into guidelines. Without this evidence a further implementation of pressure monitoring into currently used devices and justification of the substantial technical and personnel demands are not warranted.

  5. Statins and cerebral hemodynamics

    PubMed Central

    Giannopoulos, Sotirios; Katsanos, Aristeidis H; Tsivgoulis, Georgios; Marshall, Randolph S

    2012-01-01

    HMG-CoA reductase inhibitors (statins) are associated with improved stroke outcome. This observation has been attributed in part to the palliative effect of statins on cerebral hemodynamics and cerebral autoregulation (CA), which are mediated mainly through the upregulation of endothelium nitric oxide synthase (eNOS). Several animal studies indicate that statin pretreatment enhances cerebral blood flow after ischemic stroke, although this finding is not further supported in clinical settings. Cerebral vasomotor reactivity, however, is significantly improved after long-term statin administration in most patients with severe small vessel disease, aneurysmal subarachnoid hemorrhage, or impaired baseline CA. PMID:22929438

  6. Hemodynamics in Idealized Stented Coronary Arteries: Important Stent Design Considerations.

    PubMed

    Beier, Susann; Ormiston, John; Webster, Mark; Cater, John; Norris, Stuart; Medrano-Gracia, Pau; Young, Alistair; Cowan, Brett

    2016-02-01

    Stent induced hemodynamic changes in the coronary arteries are associated with higher risk of adverse clinical outcome. The purpose of this study was to evaluate the impact of stent design on wall shear stress (WSS), time average WSS, and WSS gradient (WSSG), in idealized stent geometries using computational fluid dynamics. Strut spacing, thickness, luminal protrusion, and malapposition were systematically investigated and a comparison made between two commercially available stents (Omega and Biomatrix). Narrower strut spacing led to larger areas of adverse low WSS and high WSSG but these effects were mitigated when strut size was reduced, particularly for WSSG. Local hemodynamics worsened with luminal protrusion of the stent and with stent malapposition, adverse high WSS and WSSG were identified around peak flow and throughout the cardiac cycle respectively. For the Biomatrix stent, the adverse effect of thicker struts was mitigated by greater strut spacing, radial cell offset and flow-aligned struts. In conclusion, adverse hemodynamic effects of specific design features (such as strut size and narrow spacing) can be mitigated when combined with other hemodynamically beneficial design features but increased luminal protrusion can worsen the stent's hemodynamic profile significantly.

  7. Hemodynamic management of subarachnoid hemorrhage.

    PubMed

    Treggiari, Miriam M

    2011-09-01

    Hemodynamic augmentation therapy is considered standard treatment to help prevent and treat vasospasm and delayed cerebral ischemia. Standard triple-H therapy combines volume expansion (hypervolemia), blood pressure augmentation (hypertension), and hemodilution. An electronic literature search was conducted of English-language papers published between 2000 and October 2010 that focused on hemodynamic augmentation therapies in patients with subarachnoid hemorrhage. Among the eligible reports identified, 11 addressed volume expansion, 10 blood pressure management, 4 inotropic therapy, and 12 hemodynamic augmentation in patients with unsecured aneurysms. While hypovolemia should be avoided, hypervolemia did not appear to confer additional benefits over normovolemic therapy, with an excess of side effects occurring in patients treated with hypervolemic targets. Overall, hypertension was associated with higher cerebral blood flow, regardless of volume status (normo- or hypervolemia), with neurological symptom reversal seen in two-thirds of treated patients. Limited data were available for evaluating inotropic agents or hemodynamic augmentation in patients with additional unsecured aneurysms. In the context of sparse data, no incremental risk of aneurysmal rupture has been reported with the induction of hemodynamic augmentation. PMID:21786046

  8. Lagrangian postprocessing of computational hemodynamics

    PubMed Central

    Shadden, Shawn C.; Arzani, Amirhossein

    2014-01-01

    Recent advances in imaging, modeling and computing have rapidly expanded our capabilities to model hemodynamics in the large vessels (heart, arteries and veins). This data encodes a wealth of information that is often under-utilized. Modeling (and measuring) blood flow in the large vessels typically amounts to solving for the time-varying velocity field in a region of interest. Flow in the heart and larger arteries is often complex, and velocity field data provides a starting point for investigating the hemodynamics. This data can be used to perform Lagrangian particle tracking, and other Lagrangian-based postprocessing. As described herein, Lagrangian methods are necessary to understand inherently transient hemodynamic conditions from the fluid mechanics perspective, and to properly understand the biomechanical factors that lead to acute and gradual changes of vascular function and health. The goal of the present paper is to review Lagrangian methods that have been used in post-processing velocity data of cardiovascular flows. PMID:25059889

  9. Hemodynamic aspects of Alzheimer's disease.

    PubMed

    Nagata, Ken; Sato, Mika; Satoh, Yuichi; Watahiki, Yasuhito; Kondoh, Yasushi; Sugawara, Maki; Box, Georgia; Wright, David; Leung, Sumie; Yuya, Hiromichi; Shimosegawa, Eku

    2002-11-01

    Neuroradiological functional imaging techniques demonstrate the patterns of hypoperfusion and hypometabolism that are thought to be useful in the differential diagnosis of Alzheimer's disease (AD) from other dementing disorders. Besides the distribution patterns of perfusion or energy metabolism, vascular transit time (VTT), vascular reactivity (VR), and oxygen extraction fraction (OEF), which can be measured with positron emission tomography (PET), provide hemodynamic aspects of brain pathophysiology. In order to evaluate the hemodynamic features of AD, PET studies were carried out in 20 patients with probable AD and 20 patients with vascular dementia (VaD). The PET findings were not included in their diagnostic process of AD. Using oxygen-15-labeled compounds, cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO(2)), OEF, cerebral blood volume, and VTT were measured quantitatively during resting state. To evaluate VR, CBF was also measured during CO(2) inhalation. There was a significant increase in OEF in and around the parietotemporal cortices, but both VTT and VR were well preserved in patients with AD. By contrast, VR was markedly depressed and VTT was mildly prolonged in patients with VaD. Thus, from the hemodynamic point of view, the preservation of vascular reserve may be a distinct difference between AD and VaD. Furthermore, this indicates a hemodynamic integrity of the vasculature in the level of arterioles in AD.

  10. Hemodynamics of Mechanical Circulatory Support.

    PubMed

    Burkhoff, Daniel; Sayer, Gabriel; Doshi, Darshan; Uriel, Nir

    2015-12-15

    An increasing number of devices can provide mechanical circulatory support (MCS) to patients with acute hemodynamic compromise and chronic end-stage heart failure. These devices work by different pumping mechanisms, have various flow capacities, are inserted by different techniques, and have different sites from which blood is withdrawn and returned to the body. These factors result in different primary hemodynamic effects and secondary responses of the body. However, these are not generally taken into account when choosing a device for a particular patient or while managing a patient undergoing MCS. In this review, we discuss fundamental principles of cardiac, vascular, and pump mechanics and illustrate how they provide a broad foundation for understanding the complex interactions between the heart, vasculature, and device, and how they may help guide future research to improve patient outcomes.

  11. Hemodynamic Intervention of Cerebral Aneurysms

    NASA Astrophysics Data System (ADS)

    Meng, Hui

    2005-11-01

    Cerebral aneurysm is a pathological vascular response to hemodynamic stimuli. Endovascular treatment of cerebral aneurysms essentially alters the blood flow to stop them from continued growth and eventual rupture. Compared to surgical clipping, endovascular methods are minimally invasive and hence rapidly gaining popularity. However, they are not always effective with risks of aneurysm regrowth and various complications. We aim at developing a Virtual Intervention (VI) platform that allows: patient-specific flow calculation and risk prediction as well as recommendation of tailored intervention based on quantitative analysis. This is a lofty goal requiring advancement in three areas of research: (1). Advancement of image-based CFD; (2) Understanding the biological/pathological responses of tissue to hemodynamic factors in the context of cerebral aneurysms; and (3) Capability of designing and testing patient-specific endovascular devices. We have established CFD methodologies based on anatomical geometry obtained from 3D angiographic or CT images. To study the effect of hemodynamics on aneurysm development, we have created a canine model of a vascular bifurcation anastomosis to provide the hemodynamic environment similar to those in CA. Vascular remodeling was studied using histology and compared against the flow fields obtained from CFD. It was found that an intimal pad, similar to those frequently seen clinically, developed at the flow impingement site, bordering with an area of `groove' characteristic of an early stage of aneurysm, where the micro environment exhibits an elevated wall shear stresses. To further address the molecular mechanisms of the flow-mediated aneurysm pathology, we are also developing in vitro cell culture systems to complement the in vivo study. Our current effort in endovascular device development focuses on novel stents that alters the aneurysmal flow to promote thrombotic occlusion as well as favorable remodeling. Realization of an

  12. Spatiotemporal hemodynamic response functions derived from physiology.

    PubMed

    Aquino, K M; Robinson, P A; Drysdale, P M

    2014-04-21

    Probing neural activity with functional magnetic resonance imaging (fMRI) relies upon understanding the hemodynamic response to changes in neural activity. Although existing studies have extensively characterized the temporal hemodynamic response, less is understood about the spatial and spatiotemporal hemodynamic responses. This study systematically characterizes the spatiotemporal response by deriving the hemodynamic response due to a short localized neural drive, i.e., the spatiotemporal hemodynamic response function (stHRF) from a physiological model of hemodynamics based on a poroelastic model of cortical tissue. In this study, the model's boundary conditions are clarified and a resulting nonlinear hemodynamic wave equation is derived. From this wave equation, damped linear hemodynamic waves are predicted from the stHRF. The main features of these waves depend on two physiological parameters: wave propagation speed, which depends on mean cortical stiffness, and damping which depends on effective viscosity. Some of these predictions were applied and validated in a companion study (Aquino et al., 2012). The advantages of having such a theory for the stHRF include improving the interpretation of spatiotemporal dynamics in fMRI data; improving estimates of neural activity with fMRI spatiotemporal deconvolution; and enabling wave interactions between hemodynamic waves to be predicted and exploited to improve the signal to noise ratio of fMRI. PMID:24398024

  13. Human bulbar conjunctival hemodynamics in hemoglobin SS and SC disease.

    PubMed

    Wanek, Justin; Gaynes, Bruce; Lim, Jennifer I; Molokie, Robert; Shahidi, Mahnaz

    2013-08-01

    The known biophysical variations of hemoglobin (Hb) S and Hb C may result in hemodynamic differences between subjects with SS and SC disease. The purpose of this study was to measure and compare conjunctival hemodynamics between subjects with Hb SS and SC hemoglobinopathies. Image sequences of the conjunctival microcirculation were acquired in 9 healthy control subjects (Hb AA), 24 subjects with SC disease, and 18 subjects with SS disease, using a prototype imaging system. Diameter (D) and blood velocity (V) measurements were obtained in multiple venules of each subject. Data were categorized according to venule caliber by averaging V and D for venules with diameters less than (vessel size 1) or greater than (vessel size 2) 15 µm. V in vessel size 2 was significantly greater than V in vessel size 1 in the AA and SS groups (P ≥ 0.009), but not in the SC group (P = 0.1). V was significantly lower in the SC group as compared to the SS group (P = 0.03). In AA and SS groups, V correlated with D (P ≤ 0.005), but the correlation was not statistically significant in the SC group (P = 0.08). V was inversely correlated with hematocrit in the SS group for large vessels (P = 0.03); however, no significant correlation was found in the SC group (P ≥ 0.2). Quantitative assessment of conjunctival microvascular hemodynamics in SS and SC disease may advance understanding of sickle cell disease pathophysiology and thereby improve therapeutic interventions.

  14. Hemodynamics driven cardiac valve morphogenesis.

    PubMed

    Steed, Emily; Boselli, Francesco; Vermot, Julien

    2016-07-01

    Mechanical forces are instrumental to cardiovascular development and physiology. The heart beats approximately 2.6 billion times in a human lifetime and heart valves ensure that these contractions result in an efficient, unidirectional flow of the blood. Composed of endocardial cells (EdCs) and extracellular matrix (ECM), cardiac valves are among the most mechanically challenged structures of the body both during and after their development. Understanding how hemodynamic forces modulate cardiovascular function and morphogenesis is key to unraveling the relationship between normal and pathological cardiovascular development and physiology. Most valve diseases have their origins in embryogenesis, either as signs of abnormal developmental processes or the aberrant re-expression of fetal gene programs normally quiescent in adulthood. Here we review recent discoveries in the mechanobiology of cardiac valve development and introduce the latest technologies being developed in the zebrafish, including live cell imaging and optical technologies, as well as modeling approaches that are currently transforming this field. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

  15. Hemodynamic Responses Associated with Post-exercise Hypotension in Normotensive Black Males.

    ERIC Educational Resources Information Center

    Headley, Samuel A.; And Others

    The purpose of this study was to characterize the hemodynamic responses during recovery from moderate intensity exercise in young Black normotensive males. Nineteen normotensive men (age 24-26 years) walked continuously on a treadmill for 40 minutes at 50-60 percent heart rate reserve. Following exercise, blood pressure (by auscultation) and…

  16. Hemodynamic Features of Symptomatic Vertebrobasilar Disease

    PubMed Central

    Amin-Hanjani, Sepideh; Du, Xinjian; Rose-Finnell, Linda; Pandey, Dilip K.; Richardson, DeJuran; Thulborn, Keith R.; Elkind, Mitchell S.V.; Zipfel, Gregory J.; Liebeskind, David S.; Silver, Frank L.; Kasner, Scott E.; Aletich, Victor A.; Caplan, Louis R.; Derdeyn, Colin P.; Gorelick, Philip B; Charbel, Fady T.

    2015-01-01

    Background and Purpose Atherosclerotic vertebrobasilar (VB) disease is an important etiology of posterior circulation stroke. To examine the role of hemodynamic compromise, a prospective multi-center study, Vertebrobasilar Flow Evaluation and Risk of Transient Ischemic Attack and Stroke (VERiTAS), was conducted. Here we report clinical features and vessel flow measurements from the study cohort. Methods Patients with recent VB TIA or stroke and ≥50% atherosclerotic stenosis or occlusion in vertebral (VA) and/or basilar (BA) arteries were enrolled. Large vessel flow in the VB territory was assessed using quantitative MRA. Results The cohort (n=72, 44% female) had a mean age of 65.6 years; 72% presented with ischemic stroke. Hypertension (93%) and hyperlipidemia (81%) were the most prevalent vascular risk factors. BA flows correlated negatively with percentage stenosis in the affected vessel, and positively to the minimal diameter at the stenosis site (p<0.01). A relative threshold effect was evident, with flows dropping most significantly with ≥80% stenosis/occlusion (p<0.05). Tandem disease involving the BA and either/both VAs had the greatest negative impact on immediate downstream flow in the BA (43 ml/min vs. 71 ml/min, p=0.01). Distal flow status assessment, based on an algorithm incorporating collateral flow by examining distal vessels (BA and posterior cerebral arteries), correlated neither with multifocality of disease nor severity of the maximal stenosis. Conclusions Flow in stenotic posterior circulation vessels correlates with residual diameter, and drops significantly with tandem disease. However, distal flow status, incorporating collateral capacity, is not well predicted by the severity or location of the disease. PMID:25977279

  17. Post-stenotic Recirculating Flow May Cause Hemodynamic Perforator Infarction

    PubMed Central

    Kim, Bum Joon; Ha, Hojin; Huh, Hyung Kyu; Kim, Guk Bae; Kim, Jong S.; Kim, Namkug; Lee, Sang-Joon; Kang, Dong-Wha; Kwon, Sun U.

    2016-01-01

    Background and Purpose The primary mechanism underlying paramedian pontine infarction (PPI) is atheroma obliterating the perforators. Here, we encountered a patient with PPI in the post-stenotic area of basilar artery (BA) without a plaque, shown by high-resolution magnetic resonance imaging (HR-MRI). We performed an experiment using a 3D-printed BA model and a particle image velocimetry (PIV) to explore the hemodynamic property of the post-stenotic area and the mechanism of PPI. Methods 3D-model of a BA stenosis was reconstructed with silicone compound using a 3D-printer based on the source image of HR-MRI. Working fluid seeded with fluorescence particles was used and the velocity of those particles was measured horizontally and vertically. Furthermore, microtubules were inserted into the posterior aspect of the model to measure the flow rates of perforators (pre-and post-stenotic areas). The flow rates were compared between the microtubules. Results A recirculating flow was observed from the post-stenotic area in both directions forming a spiral shape. The velocity of the flow in these regions of recirculation was about one-tenth that of the flow in other regions. The location of recirculating flow well corresponded with the area with low-signal intensity at the time-of-flight magnetic resonance angiography and the location of PPI. Finally, the flow rate through the microtubule inserted into the post-stenotic area was significantly decreased comparing to others (P<0.001). Conclusions Perforator infarction may be caused by a hemodynamic mechanism altered by stenosis that induces a recirculation flow. 3D-printed modeling and PIV are helpful understanding the hemodynamics of intracranial stenosis. PMID:26687122

  18. Computational study of anterior communicating artery hemodynamics before aneurysm formation

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Putman, Christopher M.; Cebral, Juan R.

    2012-03-01

    It is widely accepted that complexity in the flow pattern at the anterior communicating artery (AComA) is associated with the high rate of aneurysm formation in that location observed in large studies. A previous computational hemodynamic study showed a possible association between high maximum intraaneurysmal wall shear stress (WSS) at the systolic peak with rupture in a cohort of AComA aneurysms. In another study it was observed a connection between location of aneurysm blebs and regions of high WSS in models where blebs were virtually removed. However, others reported associations between low WSS and either rupture or blister formation. The purpose of this work is to study associations between hemodynamic patterns and AComA aneurysm initiation by comparing hemodynamics in the aneurysm and the normal model where the aneurysm was computationally removed. Vascular models of both right and left circulation were independently reconstructed from three-dimensional rotational angiography images using deformable models, and fused using a surface merging algorithm. The geometric models were then used to generate high-quality volumetric finite element grids of tetrahedra with an advancing front technique. For each patient, the second anatomical model was created by digitally removing the aneurysm. It was iteratively achieved by applying a Laplacian smoothing filter and remeshing the surface. Finite element blood flow numerical simulations were performed. It was observed that aneurysms initiated in regions of high and moderate WSS in the counterpart normal models. Adjacent or close to those regions, low WSS portions of the arterial wall were not affected by the disease.

  19. Human bulbar conjunctival hemodynamics in hemoglobin SS and SC disease

    PubMed Central

    Wanek, Justin; Gaynes, Bruce; Lim, Jennifer I.; Molokie, Robert; Shahidi, Mahnaz

    2014-01-01

    The known biophysical variations of hemoglobin (Hb) S and Hb C may result in hemodynamic differences between subjects with SS and SC disease. The purpose of this study was to measure and compare conjunctival hemodynamics between subjects with Hb SS and SC hemoglobinopathies. Image sequences of the conjunctival microcirculation were acquired in 9 healthy control subjects (Hb AA), 24 subjects with SC disease, and 18 subjects with SS disease, using a prototype imaging system. Diameter (D) and blood velocity (V) measurements were obtained in multiple venules of each subject. Data were categorized according to venule caliber by averaging V and D for venules with diameters less than (vessel size 1) or greater than (vessel size 2) 15 µm. V in vessel size 2 was significantly greater than V in vessel size 1 in the AA and SS groups (P ≥ 0.009), but not in the SC group (P = 0.1). V was significantly lower in the SC group as compared to the SS group (P = 0.03). In AA and SS groups, V correlated with D (P ≥ 0.005), but the correlation was not statistically significant in the SC group (P = 0.08). V was inversely correlated with hematocrit in the SS group for large vessels (P = 0.03); however, no significant correlation was found in the SC group (P ≥ 0.2). Quantitative assessment of conjunctival microvascular hemodynamics in SS and SC disease may advance understanding of sickle cell disease pathophysiology and thereby improve therapeutic interventions. PMID:23657867

  20. Quantitative Characterization of the Hemodynamic Environment in Ruptured and Unruptured Brain Aneurysms

    PubMed Central

    Cebral, Juan R.; Mut, Fernando; Weir, Jane; Putman, Christopher

    2011-01-01

    Background and purpose Hemodynamics is thought to play an important role in the mechanisms of aneurysm pathogenesis, progression and rupture. The purpose of this study was to define quantitative measures related to qualitative flow characteristics previously analyzed and to investigate their relationship to aneurysm rupture. Methods The hemodynamic environments in 210 cerebral aneurysms were analyzed using image-based CFD under different flow conditions. Quantitative hemodynamic variables were defined and extracted from the simulation results. A statistical analysis of the relationship to the previous history of aneurysm rupture was performed, and the variability with flow conditions was assessed. Results Ruptured aneurysms were more likely to have larger inflow concentrations, larger maximum wall shear stress (WSS), larger shear concentrations and lower viscous dissipation ratios than unruptured aneurysms. Areas under low WSS and measures of abnormally low shear force distributions of ruptured and unruptured aneurysms were not statistically different. Although the values of hemodynamic quantities changed with different flow conditions, the statistical differences or ratios between their mean values over the ruptured and unruptured groups were maintained, for both pulsatile and steady flows. Conclusions Concentrated inflow streams and WSS distributions with elevated levels of maximal WSS and low aneurysmal viscous dissipation are statistically associated with a clinical history of prior aneurysm rupture. In contrast, the area and total viscous shear force applied in the aneurysm region subjected to abnormally low WSS levels are not. This study highlights the potential for image-based CFD for investigating aneurysm evolution mechanisms and for clinical assessment of aneurysm risks. PMID:21127144

  1. Basic Perforator Flap Hemodynamic Mathematical Model

    PubMed Central

    Tao, Youlun; Ding, Maochao; Wang, Aiguo; Zhuang, Yuehong; Chang, Shi-Min; Mei, Jin; Hallock, Geoffrey G.

    2016-01-01

    Background: A mathematical model to help explain the hemodynamic characteristics of perforator flaps based on blood flow resistance systems within the flap will serve as a theoretical guide for the future study and clinical applications of these flaps. Methods: There are 3 major blood flow resistance network systems of a perforator flap. These were defined as the blood flow resistance of an anastomosis between artery and artery of adjacent perforasomes, between artery and vein within a perforasome, and then between vein and vein corresponding to the outflow of that perforasome. From this, a calculation could be made of the number of such blood flow resistance network systems that must be crossed for all perforasomes within a perforator flap to predict whether that arrangement would be viable. Results: The summation of blood flow resistance networks from each perforasome in a given perforator flap could predict which portions would likely survive. This mathematical model shows how this is directly dependent on the location of the vascular pedicle to the flap and whether supercharging or superdrainage maneuvers have been added. These configurations will give an estimate of the hemodynamic characteristics for the given flap design. Conclusions: This basic mathematical model can (1) conveniently determine the degree of difficulty for each perforasome within a perforator flap to survive; (2) semiquantitatively allow the calculation of basic hemodynamic parameters; and (3) allow the assessment of the pros and cons expected for each pattern of perforasomes encountered clinically based on predictable hemodynamic observations. PMID:27579238

  2. Hemodynamic findings in patients with brain stroke

    PubMed Central

    Siebert, Janusz; Molisz, Andrzej; Trzeciak, Bartosz; Nyka, Walenty

    2012-01-01

    Introduction Standard procedures carried out at a stroke department in patients after a cerebral event may prove insufficient for monitoring hemodynamic indices. Impedance cardiography enables hemodynamic changes to be monitored non-invasively. The aim of the work was to describe hemodynamic parameters in patients with acute phase of ischemic and hemorrhagic stroke and to analyse the correlation between the type of hemodynamic response and long-term prognosis. Material and methods The 45 consecutive subjects with ischemic stroke and 16 with a hemorrhagic stroke were examined additionally with impedance cardiography during the first day of hospitalization. The heart contractility, pump performance, afterload and preload indices were recorded and calculated automatically and the data analyzed in terms of 6-month mortality. Results We found a significant association between the systemic vascular resistance index, Heather index, stroke index, heart rate, systolic and diastolic and mean arterial blood pressure and mortality in patients with ischemic stroke (p = 0.002, p = 0.008, p = 0.012, p = 0.005, p = 0.007, p = 0.009, p = 0.002 respectively). Logistic regression analysis identified the thoracic fluid content as the most significant variable correlating with the non-survival of the patients with ischemic stroke and in the whole group (ischemic and hemorrhagic stroke). The significant parameters were also mean arterial pressure and stroke index in ischemic stroke (the correct answer ratio was 86.67%) and heart rate in the whole group (the correct answer ratio was 80.33%). There were no significant associations in hemorrhagic stroke. Conclusions The hemodynamic parameters correlate with long term prognosis in patients with ischemic brain stroke. PMID:22662014

  3. Invasive hemodynamic characterization of heart failure with preserved ejection fraction.

    PubMed

    Andersen, Mads J; Borlaug, Barry A

    2014-07-01

    Recent hemodynamic studies have advanced our understanding of heart failure with preserved ejection fraction (HFpEF). Despite improved pathophysiologic insight, clinical trials have failed to identify an effective treatment for HFpEF. Invasive hemodynamic assessment can diagnose or exclude HFpEF, making it invaluable in understanding the basis of the disease. This article reviews the hemodynamic mechanisms underlying HFpEF and how they manifest clinically, discusses invasive hemodynamic assessment as a diagnostic tool, and explores how invasive hemodynamic profiling may allow understanding of pathophysiological differences and inform the design and entry criteria for future trials.

  4. Multi-scale modeling of hemodynamics in the cardiovascular system

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Liang, Fuyou; Wong, Jasmin; Fujiwara, Takashi; Ye, Wenjing; Tsubota, Ken-iti; Sugawara, Michiko

    2015-08-01

    The human cardiovascular system is a closed-loop and complex vascular network with multi-scaled heterogeneous hemodynamic phenomena. Here, we give a selective review of recent progress in macro-hemodynamic modeling, with a focus on geometrical multi-scale modeling of the vascular network, micro-hemodynamic modeling of microcirculation, as well as blood cellular, subcellular, endothelial biomechanics, and their interaction with arterial vessel mechanics. We describe in detail the methodology of hemodynamic modeling and its potential applications in cardiovascular research and clinical practice. In addition, we present major topics for future study: recent progress of patient-specific hemodynamic modeling in clinical applications, micro-hemodynamic modeling in capillaries and blood cells, and the importance and potential of the multi-scale hemodynamic modeling.

  5. Simultaneous hemodynamic and echocardiographic changes during abdominal gas insufflation.

    PubMed

    Myre, K; Buanes, T; Smith, G; Stokland, O

    1997-10-01

    The purpose of this study was to investigate cardiovascular changes during CO2 pneumoperitoneum. We performed simultaneous hemodynamic recordings and transesophageal echocardiographic measurements of possible alterations in cardiac dimensions. Seven patients scheduled for elective laparoscopic cholecystectomy were investigated. With an intraabdominal pressure of 15 mm Hg, mean arterial pressure increased from 75 to 93 mm Hg (p < 0.05). Despite the increase in pulmonary capillary wedge pressure (PCWP) from 10 (9.5-12) to 17 (16-19.9) mm Hg (p < 0.05), left ventricular end-diastolic area index (EDAI) did not change significantly. The cardiac index remained unchanged. Thus abdominal gas insufflation substantially alters the PCWP/EDAI relation. During pneumoperitoneum, left ventricular filling pressure, estimated by PCWP, cannot be used as an indicator of left ventricular dilation. PMID:9348623

  6. Novel MRI approaches for assessing cerebral hemodynamics in ischemic cerebrovascular disease.

    PubMed

    Donahue, Manus J; Strother, Megan K; Hendrikse, Jeroen

    2012-03-01

    Changes in cerebral hemodynamics underlie a broad spectrum of ischemic cerebrovascular disorders. An ability to accurately and quantitatively measure hemodynamic (cerebral blood flow and cerebral blood volume) and related metabolic (cerebral metabolic rate of oxygen) parameters is important for understanding healthy brain function and comparative dysfunction in ischemia. Although positron emission tomography, single-photon emission tomography, and gadolinium-MRI approaches are common, more recently MRI approaches that do not require exogenous contrast have been introduced with variable sensitivity for hemodynamic parameters. The ability to obtain hemodynamic measurements with these new approaches is particularly appealing in clinical and research scenarios in which follow-up and longitudinal studies are necessary. The purpose of this review is to outline current state-of-the-art MRI methods for measuring cerebral blood flow, cerebral blood volume, and cerebral metabolic rate of oxygen and provide practical tips to avoid imaging pitfalls. MRI studies of cerebrovascular disease performed without exogenous contrast are synopsized in the context of clinical relevance and methodological strengths and limitations.

  7. Analysis of Hemodynamics and Aneurysm Occlusion after Flow Diverting Treatment in Rabbit Models

    PubMed Central

    Cebral, Juan R.; Mut, Fernando; Raschi, Marcelo; Hodis, Simona; Ding, Yong-Hong; Erickson, Bradley J.; Kadirvel, Ramanathan; Kallmes, David F.

    2015-01-01

    Purpose to investigate the relationship between hemodynamic conditions created immediately after flow diversion and subsequent occlusion of experimental aneurysms in rabbits. Methods The hemodynamic environment before and after flow diversion treatment of elastase induced aneurysms in 20 rabbits was modeled using image-based computational fluid dynamics. Local aneurysm occlusion was quantified using a voxelization technique on 3D images acquired 8 weeks after treatment. Global and local voxel-by-voxel hemodynamic variables were used to statistically compare aneurysm regions that later thrombosed to regions that remained patent. Results Six aneurysms remained patent at 8 weeks while 14 were completely or nearly completely occluded. Patent aneurysms had statistically larger neck sizes (p=0.0015) and smaller mean transit times (p=0.02). The velocity, vorticity and shear rate were about 2.8 times (p<0.0001) larger in patent regions, i.e. had larger “flow activity”, than regions that progressed to occlusion. Statistical models based on local hemodynamic variables were capable of predicting local occlusion with good precision (84% accuracy), especially away from the neck (92–94%). Predictions near the neck were poorer (73% accuracy). Conclusion These results suggests that the dominant healing mechanism of occlusion within the aneurysm dome are related to slow flow induced thrombosis while near the neck other processes could be at play simultaneously. PMID:24729467

  8. Analysis of Hemodynamics and Aneurysm Occlusion after Flow Diverting Treatment in Rabbit Models

    PubMed Central

    Cebral, Juan R.; Mut, Fernando; Raschi, Marcelo; Hodis, Simona; Ding, Yong-Hong; Erickson, Bradley J.; Kadirvel, Ramanathan; Kallmes, David F.

    2014-01-01

    Purpose to investigate the relationship between hemodynamic conditions created immediately after flow diversion and subsequent occlusion of experimental aneurysms in rabbits. Methods The hemodynamic environment before and after flow diversion treatment of elastase induced aneurysms in 20 rabbits was modeled using image-based computational fluid dynamics. Local aneurysm occlusion was quantified using a voxelization technique on 3D images acquired 8 weeks after treatment. Global and local voxel-by-voxel hemodynamic variables were used to statistically compare aneurysm regions that later thrombosed to regions that remained patent. Results Six aneurysms remained patent at 8 weeks while 14 were completely or nearly completely occluded. Patent aneurysms had statistically larger neck sizes (p=0.0015) and smaller mean transit times (p=0.02). The velocity, vorticity and shear rate were about 2.8 times (p<0.0001) larger in patent regions, i.e. had larger “flow activity”, than regions that progressed to occlusion. Statistical models based on local hemodynamic variables were capable of predicting local occlusion with good precision (84% accuracy), especially away from the neck (92–94%). Predictions near the neck were poorer (73% accuracy). Conclusion These results suggests that the dominant healing mechanism of occlusion within the aneurysm dome are related to slow flow induced thrombosis while near the neck other processes could be at play simultaneously. PMID:24722302

  9. Hemodynamic assessment in heart failure: role of physical examination and noninvasive methods.

    PubMed

    Almeida Junior, Gustavo Luiz; Xavier, Sérgio Salles; Garcia, Marcelo Iorio; Clausell, Nadine

    2012-01-01

    Among the cardiovascular diseases, heart failure (HF) has a high rate of hospitalization, morbidity and mortality, consuming vast resources of the public health system in Brazil and other countries. The correct determination of the filling pressures of the left ventricle by noninvasive or invasive assessment is critical to the proper treatment of patients with decompensated chronic HF, considering that congestion is the main determinant of symptoms and hospitalization. Physical examination has shown to be inadequate to predict the hemodynamic pattern. Several studies have suggested that agreement on physical findings by different physicians is small and that, ultimately, adaptive physiological alterations in chronic HF mask important aspects of the physical examination. As the clinical assessment fails to predict hemodynamic aspects and because the use of Swan-Ganz catheter is not routinely recommended for this purpose in patients with HF, noninvasive hemodynamic assessment methods, such as BNP, echocardiography and cardiographic bioimpedance, are being increasingly used. The present study intends to carry out, for the clinician, a review of the role of each of these tools when defining the hemodynamic status of patients with decompensated heart failure, aiming at a more rational and individualized treatment.

  10. Hemodynamic Characteristics Regarding Recanalization of Completely Coiled Aneurysms: Computational Fluid Dynamic Analysis Using Virtual Models Comparison

    PubMed Central

    Park, Wonhyoung; Song, Yunsun; Park, Kye Jin; Koo, Hae-Won; Yang, Kuhyun

    2016-01-01

    Purpose Hemodynamic factors are considered to play an important role in initiation and progression of the recurrence after endosaccular coiling of the intracranial aneurysms. We made paired virtual models of completely coiled aneurysms which were subsequently recanalized and compared to identify hemodynamic characteristics related to the recurred aneurysmal sac. Materials and Methods We created paired virtual models of computational fluid dynamics (CFD) in five aneurysms which were initially regarded as having achieved complete occlusion and then recurred during follow-up. Paired virtual models consisted of the CFD model of 3D rotational angiography obtained in the recurred aneurysm and the control model of the initial, parent artery after artificial removal of the coiled and recanalized aneurysm. Using the CFD analysis of the virtual model, we analyzed the hemodynamic characteristics on the neck of each aneurysm before and after its recurrence. Results High wall shear stress (WSS) was identified at the cross-sectionally identified aneurysm neck at which recurrence developed in all cases. A small vortex formation with relatively low velocity in front of the neck was also identified in four cases. The aneurysm recurrence locations corresponded to the location of high WSS and/or small vortex formation. Conclusion Recanalized aneurysms revealed increased WSS and small vortex formation at the cross-sectional neck of the aneurysm. This observation may partially explain the hemodynamic causes of future recanalization after coil embolization. PMID:26958410

  11. Time-Varying Modeling of Cerebral Hemodynamics

    PubMed Central

    Marmarelis, Vasilis Z.; Shin, Dae C.; Orme, Melissa; Zhang, Rong

    2014-01-01

    The scientific and clinical importance of cerebral hemodynamics has generated considerable interest in their quantitative understanding via computational modeling. In particular, two aspects of cerebral hemodynamics, Cerebral Flow Autoregulation (CFA) and CO2 Vasomotor Reactivity (CVR), have attracted much attention because they are implicated in many important clinical conditions and pathologies (orthostatic intolerance, syncope, hypertension, stroke, vascular dementia, MCI, Alzheimer’s disease and other neurodegenerative diseases with cerebrovascular components). Both CFA and CVR are dynamic physiological processes by which cerebral blood flow is regulated in response to fluctuations in cerebral perfusion pressure and blood CO2 tension. Several modeling studies to date have analyzed beat-to-beat hemodynamic data in order to advance our quantitative understanding of CFA-CVR dynamics. A confounding factor in these studies is the fact that the dynamics of the CFA-CVR processes appear to vary with time (i.e. changes in cerebrovascular characteristics) due to neural, endocrine and metabolic effects. This paper seeks to address this issue by tracking the changes in linear time-invariant models obtained from short successive segments of data from 10 healthy human subjects. The results suggest that systemic variations exist but have stationary statistics and, therefore, the use of time-invariant modeling yields “time-averaged models” of physiological and clinical utility. PMID:24184697

  12. Time-varying modeling of cerebral hemodynamics.

    PubMed

    Marmarelis, Vasilis Z; Shin, Dae C; Orme, Melissa; Rong Zhang

    2014-03-01

    The scientific and clinical importance of cerebral hemodynamics has generated considerable interest in their quantitative understanding via computational modeling. In particular, two aspects of cerebral hemodynamics, cerebral flow autoregulation (CFA) and CO2 vasomotor reactivity (CVR), have attracted much attention because they are implicated in many important clinical conditions and pathologies (orthostatic intolerance, syncope, hypertension, stroke, vascular dementia, mild cognitive impairment, Alzheimer's disease, and other neurodegenerative diseases with cerebrovascular components). Both CFA and CVR are dynamic physiological processes by which cerebral blood flow is regulated in response to fluctuations in cerebral perfusion pressure and blood CO2 tension. Several modeling studies to date have analyzed beat-to-beat hemodynamic data in order to advance our quantitative understanding of CFA-CVR dynamics. A confounding factor in these studies is the fact that the dynamics of the CFA-CVR processes appear to vary with time (i.e., changes in cerebrovascular characteristics) due to neural, endocrine, and metabolic effects. This paper seeks to address this issue by tracking the changes in linear time-invariant models obtained from short successive segments of data from ten healthy human subjects. The results suggest that systemic variations exist but have stationary statistics and, therefore, the use of time-invariant modeling yields "time-averaged models" of physiological and clinical utility.

  13. Role and Effectiveness of Percutaneous Arterial Embolization in Hemodynamically Unstable Patients with Ruptured Splanchnic Artery Pseudoaneurysms

    SciTech Connect

    Dohan, Anthony; Eveno, Clarisse; Dautry, Raphael Guerrache, Youcef; Camus, Marine; Boudiaf, Mourad; Gayat, Etienne; Dref, Olivier Le Sirol, Marc Soyer, Philippe

    2015-08-15

    PurposeTo assess the role and effectiveness of percutaneous arterial embolization (TAE) in patients with hemodynamic instability due to hypovolemic shock secondary to ruptured splanchnic artery pseudoaneurysms (SAPA).Materials and MethodsSeventeen patients (11 men, 6 women; mean age, 53 years) with hemodynamic instability (systolic blood pressure <90 mmHg) due to hypovolemic shock secondary to ruptured SAPA were treated by TAE. Clinical files, multidetector row computed tomography angiography, and angiographic examinations along with procedure details were reviewed.ResultsSeventeen SAPAs were present, predominantly located on gastroduodenal or pancreatic arteries (9/17; 53 %). Angiography showed extravasation of contrast medium from SAPA in 15/17 patients (88 %). Technical success rate of TAE was 100 %. TAE was performed using metallic coils in all patients (100 %), in association with gelatin sponge in 5/17 patients (29 %). TAE allowed controlling the bleeding and returning to normal hemodynamic status in 16/17 patients (94 %). In 1/17 patient (6 %), surgery was needed to definitively control the bleeding. The mortality and morbidity rate of TAE at 30 days were 0 and 12 %, respectively. Morbidity consisted in coil migration in 1/17 patient (6 %) and transient serum liver enzyme elevation in 1/17 patient (6 %).ConclusionTAE is an effective and safe treatment option for ruptured SAPA in hemodynamically unstable patients, with a success rate of 94 %. Our results suggest that TAE should be the favored option in patients with hemodynamic instability due to ruptured SAPA.

  14. Comparison of Dexmedetomidine and Remifentanil on Airway Reflex and Hemodynamic Changes during Recovery after Craniotomy

    PubMed Central

    Kim, Hyunzu; Min, Kyeong Tae; Lee, Jeong Rim; Ha, Sang Hee; Lee, Woo Kyung; Seo, Jae Hee

    2016-01-01

    Purpose During emergence from anesthesia for a craniotomy, maintenance of hemodynamic stability and prompt evaluation of neurological status is mandatory. The aim of this prospective, randomized, double-blind study was to compare the effects of dexmedetomidine and remifentanil on airway reflex and hemodynamic change in patients undergoing craniotomy. Materials and Methods Seventy-four patients undergoing clipping of unruptured cerebral aneurysm were recruited. In the dexmedetomidine group, patients were administered dexmedetomidine (0.5 µg/kg) for 5 minutes, while the patients of the remifentanil group were administered remifentanil with an effect site concentration of 1.5 ng/mL until endotracheal extubation. The incidence and severity of cough and hemodynamic variables were measured during the recovery period. Hemodynamic variables, respiration rate, and sedation scale were measured after extubation and in the post-anesthetic care unit (PACU). Results The incidence of grade 2 and 3 cough at the point of extubation was 62.5% in the dexmedetomidine group and 53.1% in the remifentanil group (p=0.39). Mean arterial pressure (p=0.01) at admission to the PACU and heart rate (p=0.04 and 0.01, respectively) at admission and at 10 minutes in the PACU were significantly lower in the dexmedetomidine group. Respiration rate was significantly lower in the remifentanil group at 2 minutes (p<0.01) and 5 minutes (p<0.01) after extubation. Conclusion We concluded that a single bolus of dexmedetomidine (0.5 µg/kg) and remifentanil infusion have equal effectiveness in attenuating coughing and hemodynamic changes in patients undergoing cerebral aneurysm clipping; however, dexmedetomidine leads to better preservation of respiration. PMID:27189295

  15. Effect of Sildenafil on Neuropathic Pain and Hemodynamics in Rats

    PubMed Central

    Huang, Lan Ji; Choi, Jeong Il; Kim, Woong Mo; Lee, Hyung Gon; Kim, Yeo Ok

    2010-01-01

    Purpose The inhibition of phosphodiesterase 5 produces an antinociception through the increase of cyclic guanosine monophosphate (cGMP), and increasing cGMP levels enhance the release of γ-aminobutyric acid (GABA). Furthermore, this phosphodiesterase 5 plays a pivotal role in the regulation of the vasodilatation associated to cGMP. In this work, we examined the contribution of GABA receptors to the effect of sildenafil, a phosphodiesterase 5 inhibitor, in a neuropathic pain rat, and assessed the hemodynamic effect of sildenafil in normal rats. Materials and Methods Neuropathic pain was induced by ligation of L5/6 spinal nerves in Sprague-Dawley male rats. After observing the effect of intravenous sildenafil on neuropathic pain, GABAA receptor antagonist (bicuculline) and GABAB receptor antagonist (saclofen) were administered prior to delivery of sildenafil to determine the role of GABA receptors in the activity of sildenafil. For hemodynamic measurements, catheters were inserted into the tail artery. Mean arterial pressure (MAP) and heart rate (HR) were measured over 60 min following administration of sildenafil. Results Intravenous sildenafil dose-dependently increased the withdrawal threshold to the von Frey filament application in the ligated paw. Intravenous bicuculline and saclofen reversed the antinociception of sildenafil. Intravenous sildenafil increased the magnitude of MAP reduction at the maximal dosage, but it did not affect HR response. Conclusion These results suggest that sildenafil is active in causing neuropathic pain. Both GABAA and GABAB receptors are involved in the antinociceptive effect of sildenafil. Additionally, intravenous sildenafil reduces MAP without affecting HR. PMID:20046518

  16. Hemodynamic and metabolic effects of cerebral revascularization.

    PubMed

    Leblanc, R; Tyler, J L; Mohr, G; Meyer, E; Diksic, M; Yamamoto, L; Taylor, L; Gauthier, S; Hakim, A

    1987-04-01

    Pre- and postoperative positron emission tomography (PET) was performed in six patients undergoing extracranial to intracranial bypass procedures for the treatment of symptomatic extracranial carotid occlusion. The six patients were all men, aged 52 to 68 years. Their symptoms included transient ischemic attacks (five cases), amaurosis fugax (two cases), and completed stroke with good recovery (one case). Positron emission tomography was performed within 4 weeks prior to surgery and between 3 to 6 months postoperatively, using oxygen-15-labeled CO, O2, and CO2 and fluorine-18-labeled fluorodeoxyglucose. Cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rates for oxygen and glucose (CMRO2 and CMRGlu), and the oxygen extraction fraction (OEF) were measured in both hemispheres. Preoperatively, compared to five elderly control subjects, patients had increased CBV, a decreased CBF/CBV ratio, and decreased CMRO2, indicating reduced cerebral perfusion pressure and depressed oxygen metabolism. The CBF was decreased in only one patient who had bilateral carotid occlusions; the OEF, CMRGlu, and CMRO2/CMRGlu and CMRGlu/CBF ratios were not significantly different from control measurements. All bypasses were patent and all patients were asymptomatic following surgery. Postoperative PET revealed decreased CBV and an increased CBF/CBV ratio, indicating improved hemodynamic function and oxygen hypometabolism. This was associated with increased CMRO2 in two patients in whom the postoperative OEF was also increased. The CMRGlu and CMRGlu/CBF ratio were increased in five patients. Changes in CBF and the CMRO2/CMRGlu ratio were variable. One patient with preoperative progressive mental deterioration, documented by serial neuropsychological testing and decreasing CBF and CMRO2, had improved postoperative CBF and CMRO2 concomitant with improved neuropsychological functioning. It is concluded that symptomatic carotid occlusion is associated with altered

  17. [Hemodynamic monitoring in the critically patient. Recomendations of the Cardiological Intensive Care and CPR Working Group of the Spanish Society of Intensive Care and Coronary Units].

    PubMed

    Ochagavía, A; Baigorri, F; Mesquida, J; Ayuela, J M; Ferrándiz, A; García, X; Monge, M I; Mateu, L; Sabatier, C; Clau-Terré, F; Vicho, R; Zapata, L; Maynar, J; Gil, A

    2014-04-01

    Hemodynamic monitoring offers valuable information on cardiovascular performance in the critically ill, and has become a fundamental tool in the diagnostic approach and in the therapy guidance of those patients presenting with tissue hypoperfusion. From introduction of the pulmonary artery catheter to the latest less invasive technologies, hemodynamic monitoring has been surrounded by many questions regarding its usefulness and its ultimate impact on patient prognosis. The Cardiological Intensive Care and CPR Working Group (GTCIC-RCP) of the Spanish Society of Intensive Care and Coronary Units (SEMICYUC) has recently impulsed the development of an updating series in hemodynamic monitoring. Now, a final series of recommendations are presented in order to analyze essential issues in hemodynamics, with the purpose of becoming a useful tool for residents and critical care practitioners involved in the daily management of critically ill patients.

  18. Empirical Evaluation of Visual Fatigue from Display Alignment Errors Using Cerebral Hemodynamic Responses

    PubMed Central

    Wiyor, Hanniebey D.; Ntuen, Celestine A.

    2013-01-01

    The purpose of this study was to investigate the effect of stereoscopic display alignment errors on visual fatigue and prefrontal cortical tissue hemodynamic responses. We collected hemodynamic data and perceptual ratings of visual fatigue while participants performed visual display tasks on 8 ft × 6 ft NEC LT silver screen with NEC LT 245 DLP projectors. There was statistical significant difference between subjective measures of visual fatigue before air traffic control task (BATC) and after air traffic control task (ATC 3), (P < 0.05). Statistical significance was observed between left dorsolateral prefrontal cortex oxygenated hemoglobin (l DLPFC-HbO2), left dorsolateral prefrontal cortex deoxygenated hemoglobin (l DLPFC-Hbb), and right dorsolateral prefrontal cortex deoxygenated hemoglobin (r DLPFC-Hbb) on stereoscopic alignment errors (P < 0.05). Thus, cortical tissue oxygenation requirement in the left hemisphere indicates that the effect of visual fatigue is more pronounced in the left dorsolateral prefrontal cortex. PMID:27006917

  19. Advanced Hemodynamic Management in Patients with Septic Shock

    PubMed Central

    Huber, Wolfgang; Nierhaus, Axel; Kluge, Stefan; Reuter, Daniel A.; Wagner, Julia Y.

    2016-01-01

    In patients with sepsis and septic shock, the hemodynamic management in both early and later phases of these “organ dysfunction syndromes” is a key therapeutic component. It needs, however, to be differentiated between “early goal-directed therapy” (EGDT) as proposed for the first 6 hours of emergency department treatment by Rivers et al. in 2001 and “hemodynamic management” using advanced hemodynamic monitoring in the intensive care unit (ICU). Recent large trials demonstrated that nowadays protocolized EGDT does not seem to be superior to “usual care” in terms of a reduction in mortality in emergency department patients with early identified septic shock who promptly receive antibiotic therapy and fluid resuscitation. “Hemodynamic management” comprises (a) making the diagnosis of septic shock as one differential diagnosis of circulatory shock, (b) assessing the hemodynamic status including the identification of therapeutic conflicts, and (c) guiding therapeutic interventions. We propose two algorithms for hemodynamic management using transpulmonary thermodilution-derived variables aiming to optimize the cardiocirculatory and pulmonary status in adult ICU patients with septic shock. The complexity and heterogeneity of patients with septic shock implies that individualized approaches for hemodynamic management are mandatory. Defining individual hemodynamic target values for patients with septic shock in different phases of the disease must be the focus of future studies. PMID:27703980

  20. Review: hemodynamic response to carbon monoxide

    SciTech Connect

    Penney, D.G.

    1988-04-01

    Historically, and at present, carbon monoxide is a major gaseous poison responsible for widespread morbidity and mortality. From threshold to maximal nonlethal levels, a variety of cardiovascular changes occur, both immediately and in the long term, whose homeostatic function it is to renormalize tissue oxygen delivery. However, notwithstanding numerous studies over the past century, the literature remains equivocal regarding the hemodynamic responses in animals and humans, although CO hypoxia is clearly different in several respects from hypoxic hypoxia. Factors complicating interpretation of experimental findings include species, CO dose level and rate, route of CO delivery, duration, level of exertion, state of consciousness, and anesthetic agent used. Augmented cardiac output usually observed with moderate COHb may be compromised in more sever poisoning for the same reasons, such that regional or global ischemia result. The hypotension usually seen in most animal studies is thought to be a primary cause of CNS damage resulting from acute CO poisoning, yet the exact mechanism(s) remains unproven in both animals and humans, as does the way in which CO produces hypotension. This review briefly summarizes the literature relevant to the short- and long-term hemodynamic responses reported in animals and humans. It concludes by presenting an overview using data from a single species in which the most complete work has been done to date.

  1. Hemodynamic Simulations in Dialysis Access Fistulae

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Leotta, Daniel; Beach, Kirk; Riley, James; Aliseda, Alberto

    2010-11-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis in patients with End-Stage Renal Disease. It has long been hypothesized that the hemodynamic and mechanical forces (such as wall shear stress, wall stretch, or flow- induced wall vibrations) constitute the primary external influence on the remodeling process. Given that nearly 50% of fistulae fail after one year, understanding fistulae hemodynamics is an important step toward improving patency in the clinic. We perform numerical simulations of the flow in patient-specific models of AV fistulae reconstructed from 3D ultrasound scans with physiologically-realistic boundary conditions also obtained from Doppler ultrasound. Comparison of the flow features in different geometries and configurations e.g. end-to-side vs. side-to-side, with the in vivo longitudinal outcomes will allow us to hypothesize which flow conditions are conducive to fistulae success or failure. The flow inertia and pulsatility in the simulations (mean Re 700, max Re 2000, Wo 4) give rise to complex secondary flows and coherent vortices, further complicating the spatio- temporal variability of the wall pressure and shear stresses. Even in mature fistulae, the anastomotic regions are subjected to non-physiological shear stresses (>10.12pcPa) which may potentially lead to complications.

  2. Local and global contributions to hemodynamic activity in mouse cortex

    PubMed Central

    Pisauro, M. Andrea; Benucci, Andrea

    2016-01-01

    Imaging techniques such as functional magnetic resonance imaging seek to estimate neural signals in local brain regions through measurements of hemodynamic activity. However, hemodynamic activity is accompanied by large vascular fluctuations of unclear significance. To characterize these fluctuations and their impact on estimates of neural signals, we used optical imaging in visual cortex of awake mice. We found that hemodynamic activity can be expressed as the sum of two components, one local and one global. The local component reflected presumed neural signals driven by visual stimuli in the appropriate retinotopic region. The global component constituted large fluctuations shared by larger cortical regions, which extend beyond visual cortex. These fluctuations varied from trial to trial, but they did not constitute noise; they correlated with pupil diameter, suggesting that they reflect variations in arousal or alertness. Distinguishing local and global contributions to hemodynamic activity may help understand neurovascular coupling and interpret measurements of hemodynamic responses. PMID:26984421

  3. Nonlinear extension of a hemodynamic linear model for coherent hemodynamics spectroscopy.

    PubMed

    Sassaroli, Angelo; Kainerstorfer, Jana M; Fantini, Sergio

    2016-01-21

    In this work, we are proposing an extension of a recent hemodynamic model (Fantini, 2014a), which was developed within the framework of a novel approach to the study of tissue hemodynamics, named coherent hemodynamics spectroscopy (CHS). The previous hemodynamic model, from a signal processing viewpoint, treats the tissue microvasculature as a linear time-invariant system, and considers changes of blood volume, capillary blood flow velocity and the rate of oxygen diffusion as inputs, and the changes of oxy-, deoxy-, and total hemoglobin concentrations (measured in near infrared spectroscopy) as outputs. The model has been used also as a forward solver in an inversion procedure to retrieve quantitative parameters that assess physiological and biological processes such as microcirculation, cerebral autoregulation, tissue metabolic rate of oxygen, and oxygen extraction fraction. Within the assumption of "small" capillary blood flow velocity oscillations the model showed that the capillary and venous compartments "respond" to this input as low pass filters, characterized by two distinct impulse response functions. In this work, we do not make the assumption of "small" perturbations of capillary blood flow velocity by solving without approximations the partial differential equation that governs the spatio-temporal behavior of hemoglobin saturation in capillary and venous blood. Preliminary comparison between the linear time-invariant model and the extended model (here identified as nonlinear model) are shown for the relevant parameters measured in CHS as a function of the oscillation frequency (CHS spectra). We have found that for capillary blood flow velocity oscillations with amplitudes up to 10% of the baseline value (which reflect typical scenarios in CHS), the discrepancies between CHS spectra obtained with the linear and nonlinear models are negligible. For larger oscillations (~50%) the linear and nonlinear models yield CHS spectra with differences within typical

  4. Monitoring changes in hemodynamics following optogenetic stimulation

    NASA Astrophysics Data System (ADS)

    Frye, Seth

    The brain is composed of billions of neurons, all of which connected through a vast network. After years of study and applications of different technologies and techniques, there are still more questions than answers when it comes to the fundamental functions of the brain. This project aims to provide a new tool which can be used to gain a better understanding of the fundamental mechanisms that govern neurological processes inside the brain. In order for neural networks to operate, blood has to be supplied through neighboring blood vessels. As such, the increase or decrease in the blood supply has been used as an indicator of neural activity. The neural activity and blood supply relationship is known as neural vasculature coupling. Monitoring the hemodynamics is used as an indicator of neurological activity, but the causal relationship is an area of current research. Gaining a better understanding of the coupling of neural activity and the surrounding vasculature provides a more accurate methodology to evaluate regional neural activity. The new optical technology applied in this project provides a set of tools to both stimulate and monitor this coupling relationship. Optogenetics provides the capability of stimulating neural activity using specific wavelengths of light. Essentially this tool allows for the direct stimulation of networks of neurons by simply shining one color of light onto the brain. Optical Coherence Tomography (OCT), another new optical technology applied in this project, can record volumetric images of blood vessels and flow using only infrared light. The combination of the two optical technologies is then capable of stimulating neural activity and monitoring the hemodynamic response inside the brain using only light. As a result of this project we have successfully demonstrated the capability of both stimulating and imaging the brain using new optical technologies. The optical stimulation of neural activity has evoked a direct hemodynamic effect

  5. Spontaneous Low-Frequency Cerebral Hemodynamics Oscillations in Restless Legs Syndrome with Periodic Limb Movements During Sleep: A Near-Infrared Spectroscopy Study

    PubMed Central

    Byun, Jung-Ick; Lee, Gwan-Taek; Kim, Choong-Ki

    2016-01-01

    Background and Purpose Periodic limb movements (PLM) during sleep (PLMS) are associated with cortical and cardiovascular activation. Changes in cerebral hemodynamics caused by cortical activity can be measured using near-infrared spectroscopy (NIRS). We investigated oscillatory components of cerebral hemodynamics during PLM and different sleep stages in restless legs syndrome (RLS) patients with PLMS. Methods Four female RLS patients with PLMS, and four age- and sex-matched normal controls were included. PLM and sleep stages were scored using polysomnography, while the spontaneous cerebral hemodynamics was measured by NIRS. The phase and amplitude of the cerebral oxyhemoglobin concentration [HbO] and the deoxyhemoglobin concentration [Hb] low-frequency oscillations (LFOs) were evaluated during each sleep stage [waking, light sleep (LS; stages N1 and N2), slow-wave sleep (stage N3), and rapid eye movement (REM) sleep]. In RLS patients with PLMS, the cerebral hemodynamics during LS was divided into LS with and without PLM. Results The cerebral hemodynamics activity varied among the different sleep stages. There were changes in phase differences between [HbO] and [Hb] LFOs during the different sleep stages in the normal controls but not in the RLS patients with PLMS. The [HbO] and [Hb] LFO amplitudes were higher in the patient group than in controls during both LS with PLM and REM sleep. Conclusions The present study has demonstrated the presence of cerebral hemodynamics disturbances in RLS patients with PLMS, which may contribute to an increased risk of cerebrovascular events. PMID:26754783

  6. [Myocardial contractility and hemodynamics in hypothyroidism].

    PubMed

    Selivonenko, V G

    1977-01-01

    The author determined the phasic structure of the systole of the left ventricle by the method of polycardiography and hemodynamics in 20 patients suffering from hypothyrodism. Blood plasma and erythrocyte electrolytes were examined at the same time. Patients with hypothyroidism displayed a phasic syndrome of hypodynamia and a marked correlation between the phase of the synchronous contraction, the period of ejection, the strength of contraction of the left ventricle and the electrolyte content. Sodium and magnesium produced the greatest influence on the phasic structure of the systole; potassium and calcium had a lesser effect. The heart stroke volume diminished; as to the cardiac index, expenditure of the energy of cardiac contractions directed to the maintenance of movement of 1 litre of the minute blood volume; the external work, and the peripheral vascular resistance displayed no significant change.

  7. Hemodynamic Traveling Waves in Human Visual Cortex

    PubMed Central

    Aquino, Kevin M.; Schira, Mark M.; Robinson, P. A.; Drysdale, Peter M.; Breakspear, Michael

    2012-01-01

    Functional MRI (fMRI) experiments rely on precise characterization of the blood oxygen level dependent (BOLD) signal. As the spatial resolution of fMRI reaches the sub-millimeter range, the need for quantitative modelling of spatiotemporal properties of this hemodynamic signal has become pressing. Here, we find that a detailed physiologically-based model of spatiotemporal BOLD responses predicts traveling waves with velocities and spatial ranges in empirically observable ranges. Two measurable parameters, related to physiology, characterize these waves: wave velocity and damping rate. To test these predictions, high-resolution fMRI data are acquired from subjects viewing discrete visual stimuli. Predictions and experiment show strong agreement, in particular confirming BOLD waves propagating for at least 5–10 mm across the cortical surface at speeds of 2–12 mm s-1. These observations enable fundamentally new approaches to fMRI analysis, crucial for fMRI data acquired at high spatial resolution. PMID:22457612

  8. Hemodynamic Correlates of Cognition in Human Infants

    PubMed Central

    Aslin, Richard N.; Shukla, Mohinish; Emberson, Lauren L.

    2015-01-01

    Over the past 20 years, the field of cognitive neuroscience has relied heavily on hemodynamic measures of blood oxygenation in local regions of the brain to make inferences about underlying cognitive processes. These same functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) techniques have recently been adapted for use with human infants. We review the advantages and disadvantages of these two neuroimaging methods for studies of infant cognition, with a particular emphasis on their technical limitations and the linking hypotheses that are used to draw conclusions from correlational data. In addition to summarizing key findings in several domains of infant cognition, we highlight the prospects of improving the quality of fNIRS data from infants to address in a more sophisticated way how cognitive development is mediated by changes in underlying neural mechanisms. PMID:25251480

  9. Hemodynamic consequences of continuous arteriovenous hemofiltration.

    PubMed

    Lauer, A; Alvis, R; Avram, M

    1988-08-01

    Continuous arteriovenous hemofiltration (CAVH) is an extracorporeal treatment in which fluid, electrolytes, and low and middle molecular weight solutes are removed from the blood by ultrafiltration. It is efficacious in the management of acute or chronic renal failure complicated by fluid overload, and following surgery. In this study, cardiac filling pressures, cardiac indices, and BP were monitored in nine patients. A mean of 7 kg of fluid was removed in ten treatments without the induction of hypotension. In nine of ten treatments, cardiac index increased following fluid removal. An increment in myocardial pump function was noted even in patients with low output heart failure. This treatment differs from dialysis in its ability to remove large fluid volumes without compromising cardiac hemodynamics. In addition, CAVH may have a role in treating volume overload patients with renal insufficiency and heart failure resistant to pharmacologic intervention. PMID:3400631

  10. Fontan hemodynamics: Importance of pulmonary artery diameter

    PubMed Central

    Dasi, Lakshmi P.; KrishnankuttyRema, Resmi; Kitajima, Hiroumi D.; Pekkan, Kerem; Sundareswaran, Kartik S.; Fogel, Mark; Sharma, Shiva; Whitehead, Kevin; Kanter, Kirk; Yoganathan, Ajit P.

    2010-01-01

    Objective We quantify the geometric and hemodynamic characteristics of extracardiac and lateral tunnel Fontan surgical options and correlate certain anatomic characteristics with their hemodynamic efficiency and patient cardiac index. Methods and Results The study was conducted retrospectively on 22 patients undergoing Fontan operations (11 extracardiac and 11 lateral tunnel operations). Total cavopulmonary connection geometric parameters such as vessel areas, curvature, and offsets were quantified using a skeletonization method. Energy loss at the total cavopulmonary connection junction was available from previous in vitro experiments and computational fluid dynamic simulations for 5 and 9 patients, respectively. Cardiac index data were available for all patients. There was no significant difference in the mean and minimum cross-sectional vessel areas of the pulmonary artery between the extracardiac and lateral tunnel groups. The indexed energy dissipation within the total cavopulmonary connection was strongly correlated to minimum cross-sectional area of the pulmonary arteries (R2 value of 0.90 and P < .0002), whereas all other geometric features, including shape characteristics, had no significant correlation. Finally, cardiac index significantly correlated with the minimum pulmonary artery area (P = .006), suggesting that total cavopulmonary connection energy losses significantly affect resting cardiac output. Conclusions The minimum outlet size of the total cavopulmonary connection (ie, minimum cross section of pulmonary artery) governs the energy loss characteristics of the total cavopulmonary connection more strongly than variations in the shapes corresponding to extracardiac and lateral tunnel configurations. Differences in pulmonary artery sizes must be accounted for when comparing energy losses between extracardiac and lateral tunnel geometries. PMID:19258065

  11. Large Eddy Simulation of Powered Fontan Hemodynamics

    PubMed Central

    Delorme, Y.; Anupindi, K.; Kerlo, A.E.; Shetty, D.; Rodefeld, M.; Chen, J.; Frankel, S.

    2012-01-01

    Children born with univentricular heart disease typically must undergo three open heart surgeries within the first 2–3 years of life to eventually establish the Fontan circulation. In that case the single working ventricle pumps oxygenated blood to the body and blood returns to the lungs flowing passively through the Total Cavopulmonary Connection (TCPC) rather than being actively pumped by a subpulmonary ventricle. The TCPC is a direct surgical connection between the superior and inferior vena cava and the left and right pulmonary arteries. We have postulated that a mechanical pump inserted into this circulation providing a 3–5 mmHg pressure augmentation will reestablish bi-ventricular physiology serving as a bridge-to-recovery, bridge-to-transplant or destination therapy as a “biventricular Fontan” circulation. The Viscous Impeller Pump (VIP) has been proposed by our group as such an assist device. It is situated in the center of the 4-way TCPC intersection and spins pulling blood from the vena cavae and pushing it into the pulmonary arteries. We hypothesized that Large Eddy Simulation (LES) using high-order numerical methods are needed to capture unsteady powered and unpowered Fontan hemodynamics. Inclusion of a mechanical pump into the CFD further complicates matters due to the need to account for rotating machinery. In this study, we focus on predictions from an in-house high-order LES code (WenoHemo™) for unpowered and VIP-powered idealized TCPC hemodynamics with quantitative comparisons to Stereoscopic Particle Imaging Velocimetry (SPIV) measurements. Results are presented for both instantaneous flow structures and statistical data. Simulations show good qualitative and quantitative agreement with measured data. PMID:23177085

  12. Time evolution and hemodynamics of cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Sforza, Daniel M.; Putman, Christopher; Tateshima, Satoshi; Viñuela, Fernando; Cebral, Juan

    2011-03-01

    Cerebral aneurysm rupture is a leading cause of hemorrhagic strokes. Because they are being more frequently diagnosed before rupture and the prognosis of subarachnoid hemorrhage is poor, clinicians are often required to judge which aneurysms are prone to progression and rupture. Unfortunately, the processes of aneurysm initiation, growth and rupture are not well understood. Multiple factors associated to these processes have been identified. Our goal is to investigate two of them, arterial hemodynamics (using computational fluid dynamics) and the peri-aneurysmal environment, by studying a group of growing cerebral aneurysms that are followed longitudinally in time. Six patients with unruptured untreated brain aneurysms which exhibited growth during the observation period were selected for the study. Vascular models of each aneurysm at each observation time were constructed from the corresponding computed tomography angiography (CTA) images. Subsequently, models were aligned, and geometrical differences quantified. Blood flow was modeled with the 3D unsteady incompressible Navier-Stokes equation for a Newtonian fluid, and wall shear stress distribution and flow patterns were calculated and visualized. Analysis of the simulations and changes in geometry revealed asymmetric growth patterns and suggests that areas subject to vigorous flows, i.e. relative high wall shear stress and concentrated streamlines patterns; correspond to regions of aneurysm growth. Furthermore, in some cases the geometrical evolution of aneurysms is clearly affected by contacts with bone structures and calcifications in the wall, and as a consequence the hemodynamics is greatly modified. Thus, in these cases the peri-aneurysmal environment must be considered when analyzing aneurysm evolution.

  13. Effects of movement from a postural maintenance position on lumbar hemodynamic changes

    PubMed Central

    Kumamoto, Tsuneo; Seko, Toshiaki; Takahashi, Yui

    2016-01-01

    [Purpose] To investigate the effects of movement from a postural maintenance position on lumbar hemodynamic changes, in order to prevent lower back pain and develop exercise therapy. [Subjects and Methods] Twenty-five healthy adults (mean age: 23.2 years) participated in the study. During flexion-extension exercise, the subjects moved their trunks gradually to a flexed position from an upright posture while sitting and standing, and then returned to and maintained an upright (re-upright) position. In the extension–flexion exercise, the subjects moved their trunks gradually from an upright posture to an extended position, and back while maintaining an upright (re-upright) position. Lumbar spinal muscle activity and hemodynamic changes were evaluated during both exercises. [Results] During the flexion and extension exercises, increased trunk-flexion angle caused increased muscle activity, decreased oxygenated hemoglobin in the multifidus muscle, and increased deoxygenated hemoglobin in the multifidus and lumbar erector spinae muscles. Moreover, the muscle activities were nearly the same in the re-upright and upright positions, and total hemoglobin also increased. [Conclusion] In both standing and sitting positions, holding the trunk in a flexed position causes ischemic hemodynamic changes in the multifidus muscle; however, the hyperemic response when returning the trunk to an extended position may improve circulation. PMID:27390450

  14. Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms

    PubMed Central

    Karmonik, Christof; Fang, Yibin; Xu, Jinyu; Yu, Ying; Cao, Wei; Liu, Jianmin; Huang, Qinghai

    2016-01-01

    Background and Purpose The conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA) aneurysms. Materials and Methods In 129 PCoA aneurysms (85 ruptured, 44 unruptured), clinical, morphological and hemodynamic characteristics were compared between the ruptured and unruptured cases. Multivariate logistic regression analysis was performed to determine the discriminators for rupture status of PCoA aneurysms. Results While univariate analyses showed that the size of aneurysm dome, aspect ratio (AR), size ratio (SR), dome-to-neck ratio (DN), inflow angle (IA), normalized wall shear stress (NWSS) and percentage of low wall shear stress area (LSA) were significantly associated with PCoA aneurysm rupture status. With multivariate analyses, significance was only retained for higher IA (OR = 1.539, p < 0.001) and LSA (OR = 1.393, p = 0.041). Conclusions Hemodynamics and morphology were related to rupture status of intracranial aneurysms. Higher IA and LSA were identified as discriminators for rupture status of PCoA aneurysms. PMID:26910518

  15. A computer-based matrix for rapid calculation of pulmonary hemodynamic parameters in congenital heart disease

    PubMed Central

    Lopes, Antonio Augusto; dos Anjos Miranda, Rogério; Gonçalves, Rilvani Cavalcante; Thomaz, Ana Maria

    2009-01-01

    BACKGROUND: In patients with congenital heart disease undergoing cardiac catheterization for hemodynamic purposes, parameter estimation by the indirect Fick method using a single predicted value of oxygen consumption has been a matter of criticism. OBJECTIVE: We developed a computer-based routine for rapid estimation of replicate hemodynamic parameters using multiple predicted values of oxygen consumption. MATERIALS AND METHODS: Using Microsoft® Excel facilities, we constructed a matrix containing 5 models (equations) for prediction of oxygen consumption, and all additional formulas needed to obtain replicate estimates of hemodynamic parameters. RESULTS: By entering data from 65 patients with ventricular septal defects, aged 1 month to 8 years, it was possible to obtain multiple predictions for oxygen consumption, with clear between-age groups (P <.001) and between-methods (P <.001) differences. Using these predictions in the individual patient, it was possible to obtain the upper and lower limits of a likely range for any given parameter, which made estimation more realistic. CONCLUSION: The organized matrix allows for rapid obtainment of replicate parameter estimates, without error due to exhaustive calculations. PMID:19641642

  16. Effect of Lower Body Compression Garments on Hemodynamics in Response to Running Session

    PubMed Central

    Venckūnas, Tomas; Trinkūnas, Eugenijus; Kamandulis, Sigitas; Poderys, Jonas; Grūnovas, Albinas; Brazaitis, Marius

    2014-01-01

    Purpose. Compression garments are often worn during exercise and allegedly have ergogenic and/or physiological effects. In this study, we compared hemodynamics and running performance while wearing compression and loose-fit breeches. We hypothesized that in neutral-warm environment compression breeches impair performance by diminishing body cooling via evaporative sweat loss and redistributing blood from active musculature to skin leading to a larger rise in body temperature and prolonging recovery of hemodynamics after exercise. Methods. Changes in hemodynamics (leg blood flow, heart rate, and blood pressure during orthoclinostatic test), calf muscle tissue oxygenation, and skin and core temperatures were measured in response to 30 min running (simulation of aerobic training session) followed by maximal 400 m sprint (evaluation of running performance) in recreationally active females (25.1 ± 4.2 yrs; 63.0 ± 8.6 kg) wearing compression or loose-fit breeches in randomized fashion. Results. Wearing compression breeches resulted in larger skin temperature rise under the garment during exercise and recovery (by about 1°C, P < 0.05; statistical power > 85%), while core temperature dynamics and other measured parameters including circulation, running performance, and sensations were similar compared to wearing loose-fit breeches (P > 0.05). Conclusion. Compared with loose-fit breeches, compression breeches have neither positive nor negative physiological and performance effects for females running in thermoneutral environment. PMID:25202721

  17. 3D Hemodynamics in Intracranial Aneurysms: Influence of Size and Morphology

    PubMed Central

    Schnell, Susanne; Ansari, Sameer A.; Vakil, Parmede; Wasielewski, Marie; Carr, Maria L.; Hurley, Michael C.; Bendok, Bernard R.; Batjer, Hunt; Carroll, Timothy J.; Carr, James; Markl, Michael

    2013-01-01

    Purpose To employ 4D-flow MRI for the comprehensive in-vivo analysis of hemodynamics and its relationship to size and morphology of different intracranial aneurysms (IA). We hypothesize that different IA groups, defined by size and morphology, exhibit different velocity fields, wall shear stress and vorticity. Materials and Methods 4D-flow MRI (spatial resolution=0.99–1.8×0.78–1.46×1.2–1.4mm3, temporal resolution=44–48ms) was performed in 19 IAs (18 patients, age=55.4 ± 13.8 years) with saccular (n=16) and fusiform (n=3) morphology and different sizes ranging from small (n=8, largest dimension=6.2 ± 0.4mm) to large and giant (n=11, 25 ± 7mm). Analysis included quantification of volumetric spatial-temporal velocity distribution, vorticity, and wall shear stress (WSS) along the aneurysms 3D surface. Results 4D-flow MRI revealed distinct hemodynamic patterns for large/giant saccular aneurysms (Group 1), small saccular aneurysms (Group 2) and large/giant fusiform aneurysms (Group 3). Saccular IA (Groups 1, 2) demonstrated significantly higher peak velocities (p<0.002) and WSS (p<0.001) compared to fusiform aneurysms. Although intra-aneurysmal 3D velocity distributions were similar for Group 1 and 2, vorticity and WSS was significantly (p<0.001) different (increased in Group 1 by 54%) indicating a relationship between IA size and hemodynamics. Group 3 showed reduced velocities (p<0.001) and WSS (p<0.001). Conclusion 4D flow MRI demonstrated the influence of lesion size and morphology on aneurysm hemodynamics suggesting the potential of 4D-flow MRI to assist in the classification of individual aneurysms. PMID:24151067

  18. Photoacoustic Imaging of Vascular Hemodynamics: Validation with Blood Oxygenation Level–Dependent MR Imaging

    PubMed Central

    Rich, Laurie J.

    2015-01-01

    Purpose To noninvasively assess vascular hemodynamics with photoacoustic imaging (PAI) and blood oxygenation level–dependent (BOLD) magnetic resonance (MR) imaging in phantoms and in an animal model. Materials and Methods In vivo studies were performed with institutional animal care and use committee approval. In vitro experiments were performed by using a tissue-mimicking phantom in multiple oxygenation conditions (n = 6) to compare PAI measurements and BOLD MR imaging measurements. PAI and T2-weighted spin-echo–based BOLD MR imaging were performed to assess tumor response to carbogen (95% O2, 5% CO2) in mice with head and neck tumors before (n = 11) and after (n = 9) treatment with a vascular disrupting agent (VDA). Two-tailed Pearson correlation analysis was performed to determine the correlation between the parameters measured with PAI and BOLD MR imaging in vitro. Two-tailed paired t tests were used to compare change in tumor hemoglobin oxygen saturation (sO2) levels and BOLD signal in response to carbogen. Changes in PAI and BOLD signal intensity before and after VDA treatment were analyzed for significance by using analysis of variance with repeated measures. Results Phantom measurements yielded good correlation between photoacoustically derived sO2 levels and BOLD signal intensity (r = 0.937, P = .005) and partial pressure of oxygen (r = 0.981, P = .005). In vivo hemodynamic response to carbogen was characterized by a significant increase in tumor sO2 levels (P = .003) and BOLD signal (P = .001). When compared with pretreatment estimates, treatment with VDA resulted in a significant reduction in the tumor hemodynamic response to carbogen at PAI (P = .030). Conclusion Carbogen-based functional imaging with PAI and BOLD MR imaging enables monitoring of early changes in tumor hemodynamics after vascular targeted therapy. © RSNA, 2014 Online supplemental material is available for this article. PMID:25423146

  19. Advanced hemodynamic monitoring: principles and practice in neurocritical care.

    PubMed

    Lazaridis, Christos

    2012-02-01

    Advanced hemodynamic monitoring is necessary for many patients with acute brain and/or spinal cord injury. Optimizing cerebral and systemic physiology requires multi-organ system function monitoring. Hemodynamic manipulations are cardinal among interventions to regulate cerebral perfusion pressure and cerebral blood flow. The pulmonary artery catheter is not any more the sole tool available; less invasive and potentially more accurate methodologies have been developed and employed in the operating room and among diverse critically ill populations. These include transpulmonary thermodilution, arterial pressure pulse contour, and waveform analysis and bedside critical care ultrasound. A thorough understanding of hemodynamics and of the available monitoring modalities is an essential skill for the neurointensivist.

  20. Evaluation of Hemodynamic Parameters as Predictors of Glaucoma Progression

    PubMed Central

    Janulevičiene, Ingrida; Ehrlich, Rita; Siesky, Brent; Nedzelskienė, Irena; Harris, Alon

    2011-01-01

    Purpose. To evaluate hemodynamic parameters as possible predictors for glaucoma progression. Methods. An 18-month randomized double-masked cohort study including 30 open-angle glaucoma patients receiving fixed-combination treatment with Dorzolamide/Timolol (DTFC) or Latanoprost/Timolol (LTFC) (n = 15 per group) was performed. Intraocular pressure (IOP), arterial blood pressure (BP), ocular and diastolic perfusion pressures (OPP, DPP), color Doppler imaging, pulsatile ocular blood flow analysis, scanning laser polarimetry, and Humphrey visual field evaluations were included. Results. Both treatments showed statistically similar IOP reduction. Six patients in DTFC and 7 in LTFC group met glaucoma progression criteria. DTFC group had higher OPP, DPP, and lower vascular resistivity indices as compared to the LTFC. Progressing patients had higher nerve fiber index, lower systolic BP, OPP, DPP, higher ophthalmic and central retinal artery vascular resistance, and lower pulse volume (P < .05; t-test). Conclusions. Structural changes consistent with glaucoma progression correlate with non-IOP-dependent risk factors. PMID:21577269

  1. [Impact of aortic stiffness on central hemodynamics and cardiovascular system].

    PubMed

    Bulas, J; Potočárová, M; Filková, M; Simková, A; Murín, J

    2013-06-01

    Arterial stiffness increases as a result of degenerative processes accelerated by aging and many risk factors, namely arterial hypertension. Basic clinical examination reveals increased pulse pressure as its hemodynamic manifestation. The most serious consequence of increased vascular stiffness, which cannot be revealed by clinical examination, is a change of central hemodynamics leading to increased load of left ventricle, left ventricular hypertrophy, diastolic dysfunction and to overall increase of cardiovascular risk. This review aimed to point at some patophysiological mechanisms taking part in the development of vascular stiffness, vascular remodeling and hemodynamic consequences of these changes. This work also gives an overview of noninvasive examination methods and their characteristics enabling to evaluate the local, regional and systemic arterial stiffness and central pulse wave analysis and their meaning for central hemodynamics and heart workload. PMID:23808736

  2. An electrical network model of intracranial arteriovenous malformations: analysis of variations in hemodynamic and biophysical parameters.

    PubMed

    Hademenos, G J; Massoud, T F

    1996-12-01

    The propensity of intracranial arteriovenous malformations (AVMs) to hemorrhage is correlated significantly with their hemodynamic features. Biomathematical models offer a theoretical approach to analyse complex AVM hemodynamics, which otherwise are difficult to quantify, particularly within or in close proximity to the nidus. Our purpose was to investigate a newly developed biomathematical AVM model based on electrical network analysis in which morphological, biophysical, and hemodynamic characteristics of intracranial AVMs were replicated accurately. Several factors implemented into the model were altered systematically to study the effects of a possible wide range of normal variations in AVM hemodynamic and biophysical parameters on the behavior of this model and its fidelity to physiological reality. The model represented a complex, noncompartmentalized AVM with four arterial feeders, two draining veins, and a nidus consisting of 28 interconnected plexiform and fistulous components. Various clinically-determined experimentally-observed, or hypothetically-assumed values for the nidus vessel radii (plexiform: 0.01 cm-0.1 cm; fistulous: 0.1 cm-0.2 cm), mean systemic arterial pressure (71 mm Hg-125 mm Hg), mean arterial feeder pressures (21 mm Hg-80 mm Hg), mean draining vein pressures (5 mm Hg-23 mm Hg), wall thickness of nidus vessels (20 microns-70 microns), and elastic modulus of nidus vessels (1 x 10(4) dyn/cm2 to 1 x 10(5) dyn/cm2) were used as normal or realistic ranges of parameters implemented in the model. Using an electrical analogy of Ohm's law, flow was determined based on Poiseuille's law given the aforementioned pressures and resistance of each nidus vessel. Circuit analysis of the AVM vasculature based on the conservation of flow and voltage revealed the flow rate through each vessel in the AVM network. An expression for the risk of AVM nidus rupture was derived based on the functional distribution of the critical radii of component vessels. The two

  3. A biomathematical model of intracranial arteriovenous malformations based on electrical network analysis: theory and hemodynamics.

    PubMed

    Hademenos, G J; Massoud, T F; Viñuela, F

    1996-05-01

    Hemodynamics play a significant role in the propensity of intracranial arteriovenous malformations (AVMs) to hemorrhage and in influencing both therapeutic strategies and their complications. AVM hemodynamics are difficult to quantitate, particularly within or in close proximity to the nidus. Biomathematical models represent a theoretical method of investigating AVM hemodynamics but currently provide limited information because of the simplicity of simulated anatomic and physiological characteristics in available models. Our purpose was to develop a new detailed biomathematical model in which the morphological, biophysical, and hemodynamic characteristics of an intracranial AVM are replicated more faithfully. The technique of electrical network analysis was used to construct the biomathematical AVM model to provide an accurate rendering of transnidal and intranidal hemodynamics. The model represented a complex, noncompartmentalized AVM with 4 arterial feeders (with simulated pial and transdural supply), 2 draining veins, and a nidus consisting of 28 interconnecting plexiform and fistulous components. Simulated vessel radii were defined as observed in human AVMs. Common values were assigned for normal systemic arterial pressure, arterial feeder pressures, draining vein pressures, and central venous pressure. Using an electrical analogy of Ohm's law, flow was determined based on Poiseuille's law given the aforementioned pressures and resistances of each nidus vessel. Circuit analysis of the AVM vasculature based on the conservation of flow and voltage revealed the flow rate through each vessel in the AVM network. Once the flow rate was established, the velocity, the intravascular pressure gradient, and the wall shear stress were determined. Total volumetric flow through the AVM was 814 ml/min. Hemodynamic analysis of the AVM showed increased flow rate, flow velocity, and wall shear stress through the fistulous component. The intranidal flow rate varied from 5.5 to 57

  4. Computational Hemodynamics Framework for the Analysis of Cerebral Aneurysms

    PubMed Central

    Mut, Fernando; Löhner, Rainald; Chien, Aichi; Tateshima, Satoshi; Viñuela, Fernando; Putman, Christopher; Cebral, Juan

    2010-01-01

    Assessing the risk of rupture of intracranial aneurysms is important for clinicians because the natural rupture risk can be exceeded by the small but significant risk carried by current treatments. To this end numerous investigators have used image-based computational fluid dynamics models to extract patient-specific hemodynamics information, but there is no consensus on which variables or hemodynamic characteristics are the most important. This paper describes a computational framework to study and characterize the hemodynamic environment of cerebral aneurysms in order to relate it to clinical events such as growth or rupture. In particular, a number of hemodynamic quantities are proposed to describe the most salient features of these hemodynamic environments. Application to a patient population indicates that ruptured aneurysms tend to have concentrated inflows, concentrated wall shear stress distributions, high maximal wall shear stress and smaller viscous dissipation ratios than unruptured aneurysms. Furthermore, these statistical associations are largely unaffected by the choice of physiologic flow conditions. This confirms the notion that hemodynamic information derived from image-based computational models can be used to assess aneurysm rupture risk, to test hypotheses about the mechanisms responsible for aneurysm formation, progression and rupture, and to answer specific clinical questions. PMID:21643491

  5. Computational modeling of cardiac hemodynamics: Current status and future outlook

    NASA Astrophysics Data System (ADS)

    Mittal, Rajat; Seo, Jung Hee; Vedula, Vijay; Choi, Young J.; Liu, Hang; Huang, H. Howie; Jain, Saurabh; Younes, Laurent; Abraham, Theodore; George, Richard T.

    2016-01-01

    The proliferation of four-dimensional imaging technologies, increasing computational speeds, improved simulation algorithms, and the widespread availability of powerful computing platforms is enabling simulations of cardiac hemodynamics with unprecedented speed and fidelity. Since cardiovascular disease is intimately linked to cardiovascular hemodynamics, accurate assessment of the patient's hemodynamic state is critical for the diagnosis and treatment of heart disease. Unfortunately, while a variety of invasive and non-invasive approaches for measuring cardiac hemodynamics are in widespread use, they still only provide an incomplete picture of the hemodynamic state of a patient. In this context, computational modeling of cardiac hemodynamics presents as a powerful non-invasive modality that can fill this information gap, and significantly impact the diagnosis as well as the treatment of cardiac disease. This article reviews the current status of this field as well as the emerging trends and challenges in cardiovascular health, computing, modeling and simulation and that are expected to play a key role in its future development. Some recent advances in modeling and simulations of cardiac flow are described by using examples from our own work as well as the research of other groups.

  6. Wireless Monitoring of Liver Hemodynamics In Vivo

    SciTech Connect

    Akl, Tony; Wilson, Mark A.; Ericson, Milton Nance; Farquhar, Ethan; Cote, Gerard L.

    2014-01-01

    Liver transplants have their highest technical failure rate in the first two weeks following surgery. Currently, there are limited devices for continuous, real-time monitoring of the graft. In this work, a three wavelengths system is presented that combines near-infrared spectroscopy and photoplethysmography with a processing method that can uniquely measure and separate the venous and arterial oxygen contributions. This strategy allows for the quantification of tissue oxygen consumption used to study hepatic metabolic activity and to relate it to tissue stress. The sensor is battery operated and communicates wirelessly with a data acquisition computer which provides the possibility of implantation provided sufficient miniaturization. In two in vivo porcine studies, the sensor tracked perfusion changes in hepatic tissue during vascular occlusions with a root mean square error (RMSE) of 0.135 mL/min/g of tissue. We show the possibility of using the pulsatile wave to measure the arterial oxygen saturation similar to pulse oximetry. The signal is also used to extract the venous oxygen saturation from the direct current (DC) levels. Arterial and venous oxygen saturation changes were measured with an RMSE of 2.19% and 1.39% respectively when no vascular occlusions were induced. This error increased to 2.82% and 3.83% when vascular occlusions were induced during hypoxia. These errors are similar to the resolution of a commercial oximetry catheter used as a reference. This work is the first realization of a wireless optical sensor for continuous monitoring of hepatic hemodynamics.

  7. Hemodynamics of Curved Vessels with Stenosis

    NASA Astrophysics Data System (ADS)

    Boghosian, Michael E.; Cassel, Kevin W.

    2007-11-01

    In hemodialysis access, the brachiocephalic or upper-arm fistula has less than optimal functional rates. The cause of this reduced patency is stenosis due to intimal hyperplasia in the cephalic vein. Stenosis typically leads to thrombosis and ultimately failure of the fistula. To increase our understanding of this process, numerical simulations of the unsteady, two-dimensional, incompressible Navier-Stokes equations are solved for the flow in an infinite channel having curvature and stenosis. Physiologically relevant Reynolds numbers ranging from 300 to 1500 and stenosis percentages of 0, 25, 50, and 75 are modeled. The post-stenotic flow is characterized by strong shear layers and recirculation regions. The largest shear stresses are found just upstream of the stenosis apex. The maximum shear stress increases with increasing Reynolds number and percent stenosis. The results indicate that hemodynamic conditions in the vein after fistula creation combined with curvature of the cephalic arch lead to shear stresses that exceed normal physiological values (both minimum and maximum). In some cases, the shear stresses are sufficiently large to cause damage to the endothelium and possibly denudation.

  8. Saccades and prefrontal hemodynamics in basketball players.

    PubMed

    Fujiwara, K; Kiyota, N; Maekawa, M; Kunita, K; Kiyota, T; Maeda, K

    2009-09-01

    We investigated saccade performance and prefrontal hemodynamics in basketball players with different skill levels. Subjects were 27 undergraduate basketball players and 13 non-athlete undergraduates (control group: CON). The players were divided into two groups: those who had played in the National Athletic Meet during high school or played regularly (n=13, elite group: ELI) and those who were bench warmers (n=14, skilled group: SKI). Horizontal eye movement and oxy-, deoxy-, and total-hemoglobin (Hb) concentration in the prefrontal cortex during pro- and anti-saccade were measured using electro-oculography and near-infrared spectroscopy, respectively. Only error rate in anti-saccade was less in ELI (4.8+/-4.0%) than SKI (13.7+/-12.6%) and CON (13.9+/-8.3%) (p<0.05). In ELI alone, oxy- (-0.15+/-0.18 mmol*mm) and total-Hb (-0.12+/-0.15 mmol*mm) during anti-saccade decreased significantly compared with that during rest (p<0.05), while those in CON significantly increased (oxy-Hb: 0.17+/-0.15 mmol*mm, total-Hb: 0.14+/-0.14 mmol*mm) (p<0.05). These results suggest that inhibition of eye movement to a visual target changes from voluntary to automatic through the motor learning of basketball. PMID:19569008

  9. Effects of spaceflight on human calf hemodynamics

    NASA Technical Reports Server (NTRS)

    Watenpaugh, D. E.; Buckey, J. C.; Lane, L. D.; Gaffney, F. A.; Levine, B. D.; Moore, W. E.; Wright, S. J.; Blomqvist, C. G.

    2001-01-01

    Chronic microgravity may modify adaptations of the leg circulation to gravitational pressures. We measured resting calf compliance and blood flow with venous occlusion plethysmography, and arterial blood pressure with sphygmomanometry, in seven subjects before, during, and after spaceflight. Calf vascular resistance equaled mean arterial pressure divided by calf flow. Compliance equaled the slope of the calf volume change and venous occlusion pressure relationship for thigh cuff pressures of 20, 40, 60, and 80 mmHg held for 1, 2, 3, and 4 min, respectively, with 1-min breaks between occlusions. Calf blood flow decreased 41% in microgravity (to 1.15 +/- 0.16 ml x 100 ml(-1) x min(-1)) relative to 1-G supine conditions (1.94 +/- 0.19 ml x 100 ml(-1) x min(-1), P = 0.01), and arterial pressure tended to increase (P = 0.05), such that calf vascular resistance doubled in microgravity (preflight: 43 +/- 4 units; in-flight: 83 +/- 13 units; P < 0.001) yet returned to preflight levels after flight. Calf compliance remained unchanged in microgravity but tended to increase during the first week postflight (P > 0.2). Calf vasoconstriction in microgravity qualitatively agrees with the "upright set-point" hypothesis: the circulation seeks conditions approximating upright posture on Earth. No calf hemodynamic result exhibited obvious mechanistic implications for postflight orthostatic intolerance.

  10. Vestibular stimulation leads to distinct hemodynamic patterning

    NASA Technical Reports Server (NTRS)

    Kerman, I. A.; Emanuel, B. A.; Yates, B. J.

    2000-01-01

    Previous studies demonstrated that responses of a particular sympathetic nerve to vestibular stimulation depend on the type of tissue the nerve innervates as well as its anatomic location. In the present study, we sought to determine whether such precise patterning of vestibulosympathetic reflexes could lead to specific hemodynamic alterations in response to vestibular afferent activation. We simultaneously measured changes in systemic blood pressure and blood flow (with the use of Doppler flowmetry) to the hindlimb (femoral artery), forelimb (brachial artery), and kidney (renal artery) in chloralose-urethane-anesthetized, baroreceptor-denervated cats. Electrical vestibular stimulation led to depressor responses, 8 +/- 2 mmHg (mean +/- SE) in magnitude, that were accompanied by decreases in femoral vasoconstriction (23 +/- 4% decrease in vascular resistance or 36 +/- 7% increase in vascular conductance) and increases in brachial vascular tone (resistance increase of 10 +/- 6% and conductance decrease of 11 +/- 4%). Relatively small changes (<5%) in renal vascular tone were observed. In contrast, electrical stimulation of muscle and cutaneous afferents produced pressor responses (20 +/- 6 mmHg) that were accompanied by vasoconstriction in all three beds. These data suggest that vestibular inputs lead to a complex pattern of cardiovascular changes that is distinct from that which occurs in response to activation of other types of somatic afferents.

  11. Changes in cerebral hemodynamics during laparoscopic cholecystectomy.

    PubMed

    De Cosmo, G; Iannace, E; Primieri, P; Valente, M R; Proietti, R; Matteis, M; Silvestrini, M

    1999-10-01

    Laparoscopic surgery requires a series of procedures, including intraperitoneal CO2 insufflation, which can cause cardiovascular and hemogasanalytic modifications, potentially able to impair cerebral perfusion. The aim of this study was to evaluate changes in cerebral blood flow velocity during laparoscopic cholecystectomy. Eighteen patients undergoing laparoscopic cholecystectomy were studied. Middle cerebral artery blood flow velocity was monitored using transcranial Doppler ultrasonography. Electrical bioimpedance was employed to measure cardiac output, stroke volume and to calculate derived parameters. End-tidal CO2, mean arterial blood pressure, end expiratory anesthetic concentration and O2 saturation were monitored non-invasively. Cerebral artery blood flow velocity increased significantly after CO2 insufflation (p < 0.05) and remained stable. The highest values were reached after CO2 desufflation. A significant reduction in stroke volume and cardiac output (p < 0.05) associated with increased vascular systemic resistances (p < 0.001) was observed soon after CO2 insufflation. The decrease in cardiac output and the increase in vascular systemic resistances remained significant throughout abdominal insufflation. Heart rate and mean arterial pressure remained substantially unchanged with the exception of a significant decrease (p < 0.001) before CO2 insufflation. There was no significant change in end-tidal CO2 during abdominal insufflation. These findings suggest that the cerebrovascular system can undergo adaptive changes during all phases of laparoscopic surgery. However, the extent of cardio- and cerebrovascular variation indicates the need for careful preliminary evaluation of cerebral hemodynamics in patients with vascular disorders before laparoscopic surgery. PMID:10555187

  12. Concurrent bias correction in hemodynamic data assimilation.

    PubMed

    Hu, Zhenghui; Liu, Huafeng; Shi, Pengcheng

    2012-10-01

    Low-frequency drift in fMRI datasets can be caused by various sources and are generally not of interest in a conventional task-based fMRI experiment. This feature complicates the assimilation approach that is always under specific assumption on statistics of system uncertainties. In this paper, we present a novel approach to the assimilation of nonlinear hemodynamic system with stochastic biased noise. By treating the drift variation as a random-walk process, the assimilation problem was translated into the identification of a nonlinear system in the presence of time-varying bias. We developed a bias aware unscented Kalman estimator to efficiently handle this problem. In this framework, the estimates of bias-free states and drift are separately carried out in two parallel filters, the optimal estimates of the system states then are corrected from bias-free states with drift estimates. The approach can simultaneously deal with the fMRI responses and drift in an assimilation cycle in an on-line fashion. It makes no assumptions of the structure and statistics of the drift, thereby is particularly suited for fMRI imaging where the formulation of real drift remains difficult to acquire. Experiments with synthetic data and real fMRI data are performed to demonstrate feasibility of our approach and to explore its potential advantages over classic polynomial approach. Moreover, we include the comparison of the variability of observables from the scanner and of normalized signal used in assimilation procedure in Appendix.

  13. Saccades and prefrontal hemodynamics in basketball players.

    PubMed

    Fujiwara, K; Kiyota, N; Maekawa, M; Kunita, K; Kiyota, T; Maeda, K

    2009-09-01

    We investigated saccade performance and prefrontal hemodynamics in basketball players with different skill levels. Subjects were 27 undergraduate basketball players and 13 non-athlete undergraduates (control group: CON). The players were divided into two groups: those who had played in the National Athletic Meet during high school or played regularly (n=13, elite group: ELI) and those who were bench warmers (n=14, skilled group: SKI). Horizontal eye movement and oxy-, deoxy-, and total-hemoglobin (Hb) concentration in the prefrontal cortex during pro- and anti-saccade were measured using electro-oculography and near-infrared spectroscopy, respectively. Only error rate in anti-saccade was less in ELI (4.8+/-4.0%) than SKI (13.7+/-12.6%) and CON (13.9+/-8.3%) (p<0.05). In ELI alone, oxy- (-0.15+/-0.18 mmol*mm) and total-Hb (-0.12+/-0.15 mmol*mm) during anti-saccade decreased significantly compared with that during rest (p<0.05), while those in CON significantly increased (oxy-Hb: 0.17+/-0.15 mmol*mm, total-Hb: 0.14+/-0.14 mmol*mm) (p<0.05). These results suggest that inhibition of eye movement to a visual target changes from voluntary to automatic through the motor learning of basketball.

  14. Hemodynamics in coronary arteries with overlapping stents.

    PubMed

    Rikhtegar, Farhad; Wyss, Christophe; Stok, Kathryn S; Poulikakos, Dimos; Müller, Ralph; Kurtcuoglu, Vartan

    2014-01-22

    Coronary artery stenosis is commonly treated by stent placement via percutaneous intervention, at times requiring multiple stents that may overlap. Stent overlap is associated with increased risk of adverse clinical outcome. While changes in local blood flow are suspected to play a role therein, hemodynamics in arteries with overlapping stents remain poorly understood. In this study we analyzed six cases of partially overlapping stents, placed ex vivo in porcine left coronary arteries and compared them to five cases with two non-overlapping stents. The stented vessel geometries were obtained by micro-computed tomography of corrosion casts. Flow and shear stress distribution were calculated using computational fluid dynamics. We observed a significant increase in the relative area exposed to low wall shear stress (WSS<0.5 Pa) in the overlapping stent segments compared both to areas without overlap in the same samples, as well as to non-overlapping stents. We further observed that the configuration of the overlapping stent struts relative to each other influenced the size of the low WSS area: positioning of the struts in the same axial location led to larger areas of low WSS compared to alternating struts. Our results indicate that the overlap geometry is by itself sufficient to cause unfavorable flow conditions that may worsen clinical outcome. While stent overlap cannot always be avoided, improved deployment strategies or stent designs could reduce the low WSS burden.

  15. Magnetic Particle Imaging for High Temporal Resolution Assessment of Aneurysm Hemodynamics

    PubMed Central

    Frölich, Andreas; Spallek, Johanna; Forkert, Nils D.; Faizy, Tobias D.; Werner, Franziska; Knopp, Tobias; Krause, Dieter; Fiehler, Jens; Buhk, Jan-Hendrik

    2016-01-01

    Purpose The purpose of this work was to demonstrate the capability of magnetic particle imaging (MPI) to assess the hemodynamics in a realistic 3D aneurysm model obtained by additive manufacturing. MPI was compared with magnetic resonance imaging (MRI) and dynamic digital subtraction angiography (DSA). Materials and Methods The aneurysm model was of saccular morphology (7 mm dome height, 5 mm cross-section, 3–4 mm neck, 3.5 mm parent artery diameter) and connected to a peristaltic pump delivering a physiological flow (250 mL/min) and pulsation rate (70/min). High-resolution (4 h long) 4D phase contrast flow quantification (4D pc-fq) MRI was used to directly assess the hemodynamics of the model. Dynamic MPI, MRI, and DSA were performed with contrast agent injections (3 mL volume in 3 s) through a proximally placed catheter. Results and Discussion 4D pc-fq measurements showed distinct pulsatile flow velocities (20–80 cm/s) as well as lower flow velocities and a vortex inside the aneurysm. All three dynamic methods (MPI, MRI, and DSA) also showed a clear pulsation pattern as well as delayed contrast agent dynamics within the aneurysm, which is most likely caused by the vortex within the aneurysm. Due to the high temporal resolution of MPI and DSA, it was possible to track the contrast agent bolus through the model and to estimate the average flow velocity (about 60 cm/s), which is in accordance with the 4D pc-fq measurements. Conclusions The ionizing radiation free, 4D high resolution MPI method is a very promising tool for imaging and characterization of hemodynamics in human. It carries the possibility of overcoming certain disadvantages of other modalities like considerably lower temporal resolution of dynamic MRI and limited 2D characteristics of DSA. Furthermore, additive manufacturing is the key for translating powerful pre-clinical techniques into the clinic. PMID:27494610

  16. Effects of radiation on tumor hemodynamics and NF-kappaB in breast tumors

    NASA Astrophysics Data System (ADS)

    Stantz, Keith M.; Cao, Ning; Liu, Bo; Cao, Minsong; Chin-Sinex, Helen; Mendonca, Marc; Li, Jian Jian

    2010-02-01

    Purpose: The purpose of this study is to monitor in vivo the IR dose dependent response of NF-κB and tumor hemodynamics as a function of time. Material and Methods: An MDA-231 breast cancer cell line was stably transfected with a firefly luciferase gene within the NF-kappaB promoter. Tumors on the right flank irradiated with a single fractionated dose of 5Gy or 10Gy. Over two weeks, photoacoustic spectroscopy (PCT-S), bioluminescence imaging (BLI), and dynamic contrast enhanced CT (DCE-CT) was used to monitor hemoglobin status, NF-kappaB expression, and physiology, respectively. Results: From the BLI, an increase in NF-kappaB expression was observed in both the right (irradiation) and left (nonirradiated) tumors, which peaked at 8-12 hours, returned to basal levels after 24 hours, and increased a second time from 3 to 7 days. This data identifies both a radiation-induced bystander effect and a bimodal longitudinal response associated with NF-κB-controlled luciferase promoter. The physiological results from DCE-CT measured an increase in perfusion (26%) two days after radiation and both a decrease in perfusion and an increase in fp by week 1 (10Gy cohort). PCT-S measured increased levels of oxygen saturation two days post IR, which did not change after 1 week. Initially, NF-κB would modify hemodynamics to increase oxygen delivery after IR insult. The secondary response appears to modulate tumor angiogenesis. Conclusions: A bimodal response to radiation was detected with NF-kappaB-controlled luciferase reporter with a concomitant hemodynamic response associated with tumor hypoxia. Experiments are being performed to increase statistics.

  17. Evaluation of the Hemodynamic Response to Endotracheal Intubation Comparing the Airtraq® with Macintosh Laryngoscopes in Cardiac Surgical Patients

    PubMed Central

    Gavrilovska-Brzanov, Aleksandra; Jarallah, Mohhamed Al; Cogliati, Andrea; Mojsova-Mijovska, Maja; Mijuskovic, Dragan; Slaveski, Dimce

    2015-01-01

    Introduction: Cardiac patients are more prone to develop hemodynamic instability on induction of anesthesia and endotracheal intubation. The Airtraq® optical laryngoscope is a single-use rigid video laryngoscope that has been developed to facilitate tracheal intubation. There are limited studies comparing differences in the circulatory responses to Airtraq® and direct Macintosh larynngoscopy in cardiac patients. Aim: The purpose of our study was to evaluate whether there was clinically significant difference between the hemodynamic response to orotracheal intubation guided by either of the two devices (Airtraq® and Macintosh laryngoscopes) in patients who underwent coronary artery bypass grafting surgery. Material and methods: In this clinical study we analyzed the hemodynamic response to endotracheal intubation performed with Airtraq® or Macintosh laryngoscopes in patients who underwent elective coronary artery bypass graft surgery under general anesthesia. Results: We analyzed: blood pressure (systolic, diastolic, mean), heart rate and peripheral oxygen saturation (all notified before induction in anesthesia, immediately after induction, at the time of intubation and thereafter one and five minutes after intubation). We also recorded the maximal values of blood pressure and heart rate, as well as calculated the product of heart rate and systolic blood pressure. There were statistically significant differences in the hemodynamic response between the groups. At the time of intubation, there was significant inter-group difference in heart rate, systolic, diastolic and mean blood pressure. Endotracheal intubation with Macintosh laryngoscope was accompanied by significant increase in blood pressure and heart rate compared to Airtraq® group. Conclusion: The Airtraq® laryngoscope performed better than the Macintosh laryngoscope in terms of hemodynamic to the patient undergoing routine coronary artery bypass graft surgery. PMID:26635435

  18. Reductions in central venous pressure by lower body negative pressure or blood loss elicit similar hemodynamic responses

    PubMed Central

    Johnson, Blair D.; van Helmond, Noud; Curry, Timothy B.; van Buskirk, Camille M.; Convertino, Victor A.

    2014-01-01

    The purpose of this study was to compare hemodynamic and blood analyte responses to reduced central venous pressure (CVP) and pulse pressure (PP) elicited during graded lower body negative pressure (LBNP) to those observed during graded blood loss (BL) in conscious humans. We hypothesized that the stimulus-response relationships of CVP and PP to hemodynamic responses during LBNP would mimic those observed during BL. We assessed CVP, PP, heart rate, mean arterial pressure (MAP), and other hemodynamic markers in 12 men during LBNP and BL. Blood samples were obtained for analysis of catecholamines, hematocrit, hemoglobin, arginine vasopressin, and blood gases. LBNP consisted of 5-min stages at 0, 15, 30, and 45 mmHg of suction. BL consisted of 5 min at baseline and following three stages of 333 ml of hemorrhage (1,000 ml total). Individual r2 values and linear regression slopes were calculated to determine whether the stimulus (CVP and PP)-hemodynamic response trajectories were similar between protocols. The CVP-MAP trajectory was the only CVP-response slope that was statistically different during LBNP compared with BL (0.93 ± 0.27 vs. 0.13 ± 0.26; P = 0.037). The PP-heart rate trajectory was the only PP-response slope that was statistically different during LBNP compared with BL (−1.85 ± 0.45 vs. −0.46 ± 0.27; P = 0.024). Norepinephrine, hematocrit, and hemoglobin were all lower at termination in the BL protocol compared with LBNP (P < 0.05). Consistent with our hypothesis, LBNP mimics the hemodynamic stimulus-response trajectories observed during BL across a significant range of CVP in humans. PMID:24876357

  19. Wireless monitoring of liver hemodynamics in vivo.

    PubMed

    Akl, Tony J; Wilson, Mark A; Ericson, M Nance; Farquhar, Ethan; Coté, Gerard L

    2014-01-01

    Liver transplants have their highest technical failure rate in the first two weeks following surgery. Currently, there are limited devices for continuous, real-time monitoring of the graft. In this work, a three wavelengths system is presented that combines near-infrared spectroscopy and photoplethysmography with a processing method that can uniquely measure and separate the venous and arterial oxygen contributions. This strategy allows for the quantification of tissue oxygen consumption used to study hepatic metabolic activity and to relate it to tissue stress. The sensor is battery operated and communicates wirelessly with a data acquisition computer which provides the possibility of implantation provided sufficient miniaturization. In two in vivo porcine studies, the sensor tracked perfusion changes in hepatic tissue during vascular occlusions with a root mean square error (RMSE) of 0.135 mL/min/g of tissue. We show the possibility of using the pulsatile wave to measure the arterial oxygen saturation similar to pulse oximetry. The signal is also used to extract the venous oxygen saturation from the direct current (DC) levels. Arterial and venous oxygen saturation changes were measured with an RMSE of 2.19% and 1.39% respectively when no vascular occlusions were induced. This error increased to 2.82% and 3.83% when vascular occlusions were induced during hypoxia. These errors are similar to the resolution of a commercial oximetry catheter used as a reference. This work is the first realization of a wireless optical sensor for continuous monitoring of hepatic hemodynamics. PMID:25019160

  20. Wireless Monitoring of Liver Hemodynamics In Vivo

    PubMed Central

    Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Farquhar, Ethan; Coté, Gerard L.

    2014-01-01

    Liver transplants have their highest technical failure rate in the first two weeks following surgery. Currently, there are limited devices for continuous, real-time monitoring of the graft. In this work, a three wavelengths system is presented that combines near-infrared spectroscopy and photoplethysmography with a processing method that can uniquely measure and separate the venous and arterial oxygen contributions. This strategy allows for the quantification of tissue oxygen consumption used to study hepatic metabolic activity and to relate it to tissue stress. The sensor is battery operated and communicates wirelessly with a data acquisition computer which provides the possibility of implantation provided sufficient miniaturization. In two in vivo porcine studies, the sensor tracked perfusion changes in hepatic tissue during vascular occlusions with a root mean square error (RMSE) of 0.135 mL/min/g of tissue. We show the possibility of using the pulsatile wave to measure the arterial oxygen saturation similar to pulse oximetry. The signal is also used to extract the venous oxygen saturation from the direct current (DC) levels. Arterial and venous oxygen saturation changes were measured with an RMSE of 2.19% and 1.39% respectively when no vascular occlusions were induced. This error increased to 2.82% and 3.83% when vascular occlusions were induced during hypoxia. These errors are similar to the resolution of a commercial oximetry catheter used as a reference. This work is the first realization of a wireless optical sensor for continuous monitoring of hepatic hemodynamics. PMID:25019160

  1. Acute hemodynamic responses to weightlessness in humans

    NASA Technical Reports Server (NTRS)

    Lathers, C. M.; Charles, J. B.; Elton, K. F.; Holt, T. A.; Mukai, C.; Bennett, B. S.; Bungo, M. W.

    1989-01-01

    As NASA designs space flights requiring prolonged periods of weightlessness for a broader segment of the population, it will be important to know the acute and sustained effects of weightlessness on the cardiovascular system since this information will contribute to understanding of the clinical pharmacology of drugs administered in space. Due to operational constraints on space flights, earliest effects of weightlessness have not been documented. We examined hemodynamic responses of humans to transitions from acceleration to weightlessness during parabolic flight on NASA's KC-135 aircraft. Impedance cardiography data were collected over four sets of 8-10 parabolas, with a brief rest period between sets. Each parabola included a period of 1.8 Gz, then approximately 20 seconds of weightlessness, and finally a period of 1.6 Gz; the cycle repeated almost immediately for the remainder of the set. Subjects were semi-supine (Shuttle launch posture) for the first set, then randomly supine, sitting and standing for each subsequent set. Transition to weightlessness while standing produced decreased heart rate, increased thoracic fluid content, and increased stroke index. Surprisingly, the onset of weightlessness in the semi-supine posture produced little evidence of a headward fluid shift. Heart rate, stroke index, and cardiac index are virtually unchanged after 20 seconds of weightlessness, and thoracic fluid content is slightly decreased. Semi-supine responses run counter to Shuttle crewmember reports of noticeable fluid shift after minutes to hours in orbit. Apparently, the headward fluid shift commences in the semi-supine posture before launch. is augmented by launch acceleration, but briefly interrupted immediately in orbit, then resumes and is completed over the next hours.

  2. Cerebral hemodynamics during graded Valsalva maneuvers

    PubMed Central

    Perry, Blake G.; Cotter, James D.; Mejuto, Gaizka; Mündel, Toby; Lucas, Samuel J. E.

    2014-01-01

    The Valsalva maneuver (VM) produces large and abrupt changes in mean arterial pressure (MAP) that challenge cerebral blood flow and oxygenation. We examined the effect of VM intensity on middle cerebral artery blood velocity (MCAv) and cortical oxygenation responses during (phases I–III) and following (phase IV) a VM. Healthy participants (n = 20 mean ± SD: 27 ± 7 years) completed 30 and 90% of their maximal VM mouth pressure for 10 s (order randomized) whilst standing. Beat-to-beat MCAv, cerebral oxygenation (NIRS) and MAP across the different phases of the VM are reported as the difference from standing baseline. There were significant interaction (phase * intensity) effects for MCAv, total oxygenation index (TOI) and MAP (all P < 0.01). MCAv decreased during phases II and III (P < 0.01), with the greatest decrease during phase III (−5 ± 8 and −19 ± 15 cm·s−1 for 30 and 90% VM, respectively). This pattern was also evident in TOI (phase III: −1 ± 1 and −5 ± 4%, both P < 0.05). Phase IV increased MCAv (22 ± 15 and 34 ± 23 cm·s−1), MAP (15 ± 14 and 24 ± 17 mm Hg) and TOI (5 ± 6 and 7 ± 5%) relative to baseline (all P < 0.05). Cerebral autoregulation, indexed, as the %MCAv/%MAP ratio, showed a phase effect only (P < 0.001), with the least regulation during phase IV (2.4 ± 3.0 and 3.2 ± 2.9). These data illustrate that an intense VM profoundly affects cerebral hemodynamics, with a reactive hyperemia occurring during phase IV following modest ischemia during phases II and III. PMID:25309449

  3. Prediction of Prolonged Hemodynamic Instability During Carotid Angioplasty and Stenting

    PubMed Central

    Rhim, Jong Kook; Park, Jeong Jin; Choi, Hyuk Jai; Cho, Young Dae; Sheen, Seung Hun; Jang, Kyung-Sool

    2016-01-01

    Purpose The aim of this study was to assess the risk factors of prolonged hemodynamic instability (HDI) after carotid angioplasty and stenting (CAS). Herein, a simplified predictive scoring system for prolonged HDI is proposed. Materials and Methods Sixty-six patients who had CAS from 2011 to 2016 at a single institution were evaluated. Prolonged HDI was defined as systolic blood pressure >160 mm Hg or <90 mm Hg or heart rate <50 beats/min, lasting over 30 minutes despite medical treatments. For the study, clinical data and radiologic data, including plaque morphology and stenosis were analyzed. Results Prolonged HDI was observed in 21 patients (31.8%). Multivariable analysis revealed that calcification (OR, 6.726; p=0.006), eccentric stenosis (OR, 3.645; p=0.047) and extensive plaque distribution (OR, 7.169; p=0.006) were related to prolonged HDI. According to these results, a simplified scoring scale was proposed based on the summation of points: 2 points for calcified plaque, 2 points for extensive plaque distribution, and 1 point for eccentric stenosis. The percentages of prolonged HDI according to the total score were as follows: score 0, 8.7%; score 1, 20.0%; score 2, 38.5%; score 3, 72.7%; score 4, 66.7%; score 5, 100%. From the analysis, the total score in patients with prolonged HDI was significantly higher than those without prolonged HDI (p<0.001). Conclusion Prolonged HDI can be associated with calcification of plaque, eccentric stenosis and extensive plaque distribution, and a simplified scoring system enables prediction of prolonged HDI according to our cohort. PMID:27621949

  4. Ambient Temperature and Cerebrovascular Hemodynamics in the Elderly

    PubMed Central

    Pan, Wen-Chi; Eliot, Melissa N.; Koutrakis, Petros; Coull, Brent A.; Sorond, Farzaneh A.; Wellenius, Gregory A.

    2015-01-01

    Background and Purpose Some prior studies have linked ambient temperature with risk of cerebrovascular events. If causal, the pathophysiologic mechanisms underlying this putative association remain unknown. Temperature-related changes in cerebral vascular function may play a role, but this hypothesis has not been previously evaluated. Methods We evaluated the association between ambient temperature and cerebral vascular function among 432 participants ≥65 years old from the MOBILIZE Boston Study with data on cerebrovascular blood flow, cerebrovascular resistance, and cerebrovascular reactivity in the middle cerebral artery. We used linear regression models to assess the association of mean ambient temperature in the previous 1 to 28 days with cerebrovascular hemodynamics adjusting for potential confounding factors. Results A 10°C increase in the 21-day moving average of ambient temperature was associated with a 10.1% (95% confidence interval [CI], 2.2%, 17.3%) lower blood flow velocity, a 9.0% (95% CI, 0.7%, 18.0%) higher cerebrovascular resistance, and a 15.3% (95%CI, 2.7%, 26.4%) lower cerebral vasoreactivity. Further adjustment for ozone and fine particulate matter (PM2.5) did not materially alter the results. However, we found statistically significant interactions between ambient temperature and PM2.5 such that the association between temperature and blood flow velocity was attenuated at higher levels of PM2.5. Conclusions In this elderly population, we found that ambient temperature was negatively associated with cerebral blood flow velocity and cerebrovascular vasoreactivity and positively associated with cerebrovascular resistance. Changes in vascular function may partly underlie the observed associations between ambient temperature and risk of cerebrovascular events. PMID:26258469

  5. Prediction of Prolonged Hemodynamic Instability During Carotid Angioplasty and Stenting

    PubMed Central

    Rhim, Jong Kook; Park, Jeong Jin; Choi, Hyuk Jai; Cho, Young Dae; Sheen, Seung Hun; Jang, Kyung-Sool

    2016-01-01

    Purpose The aim of this study was to assess the risk factors of prolonged hemodynamic instability (HDI) after carotid angioplasty and stenting (CAS). Herein, a simplified predictive scoring system for prolonged HDI is proposed. Materials and Methods Sixty-six patients who had CAS from 2011 to 2016 at a single institution were evaluated. Prolonged HDI was defined as systolic blood pressure >160 mm Hg or <90 mm Hg or heart rate <50 beats/min, lasting over 30 minutes despite medical treatments. For the study, clinical data and radiologic data, including plaque morphology and stenosis were analyzed. Results Prolonged HDI was observed in 21 patients (31.8%). Multivariable analysis revealed that calcification (OR, 6.726; p=0.006), eccentric stenosis (OR, 3.645; p=0.047) and extensive plaque distribution (OR, 7.169; p=0.006) were related to prolonged HDI. According to these results, a simplified scoring scale was proposed based on the summation of points: 2 points for calcified plaque, 2 points for extensive plaque distribution, and 1 point for eccentric stenosis. The percentages of prolonged HDI according to the total score were as follows: score 0, 8.7%; score 1, 20.0%; score 2, 38.5%; score 3, 72.7%; score 4, 66.7%; score 5, 100%. From the analysis, the total score in patients with prolonged HDI was significantly higher than those without prolonged HDI (p<0.001). Conclusion Prolonged HDI can be associated with calcification of plaque, eccentric stenosis and extensive plaque distribution, and a simplified scoring system enables prediction of prolonged HDI according to our cohort.

  6. Hemodynamic Consequences of Malignant Ascites in Epithelial Ovarian Cancer Surgery∗

    PubMed Central

    Hunsicker, Oliver; Fotopoulou, Christina; Pietzner, Klaus; Koch, Mandy; Krannich, Alexander; Sehouli, Jalid; Spies, Claudia; Feldheiser, Aarne

    2015-01-01

    Abstract Malignant ascites (MA) is most commonly observed in patients scheduled for epithelial ovarian cancer (EOC) surgery and is supposed as a major risk factor promoting perioperative hemodynamic deterioration. We aimed to assess the hemodynamic consequences of MA on systemic circulation in patients undergoing cytoreductive EOC surgery. This study is a predefined post-hoc analysis of a randomized controlled pilot trial comparing intravenous solutions within a goal-directed algorithm to optimize hemodynamic therapy in patients undergoing cytoreductive EOC surgery. Ascites was used to stratify the EOC patients prior to randomization in the main study. We analyzed 2 groups according to the amount of ascites (NLAS: none or low ascites [<500 mL] vs HAS: high ascites group [>500 mL]). Differences in hemodynamic variables with respect to time were analyzed using nonparametric analysis for longitudinal data and multivariate generalized estimating equation adjusting the analysis for the randomized study groups of the main study. A total of 31 patients in the NLAS and 16 patients in the HAS group were analyzed. Although cardiac output was not different between groups suggesting a similar circulatory blood flow, the HAS group revealed higher heart rates and lower stroke volumes during surgery. There were no differences in pressure-based hemodynamic variables. In the HAS group, fluid demands, reflected by the time to reindication of a fluid challenge after preload optimization, increased steadily, whereas stroke volume could not be maintained at baseline resulting in hemodynamic instability after 1.5 h of surgery. In contrast, in the NLAS group fluid demands were stable and stroke volume could be maintained during surgery. Clinically relevant associations of the type of fluid replacement with hemodynamic consequences were particularly observed in the HAS group, in which transfusion of fresh frozen plasma (FFP) was associated to an improved circulatory flow and reduced

  7. Hemodynamic Conditions in a Failing Peripheral Artery Bypass Graft

    PubMed Central

    McGah, Patrick M.; Leotta, Daniel F.; Beach, Kirk W.; Zierler, R. Eugene; Riley, James J.; Aliseda, Alberto

    2012-01-01

    Objective The mechanisms of restenosis in autogenous vein bypass grafts placed for peripheral artery disease are not completely understood. We seek to investigate the role of hemodynamic stress in a case study of a revised bypass graft that failed due to restenosis. Methods The morphology of the lumen is reconstructed from a custom 3D ultrasound system. Scans were taken at one, six, and sixteen months after a patch angioplasty procedure. Computational hemodynamic simulations of the patient-specific model provide the blood flow features and the hemodynamic stresses on the vessel wall at the three time points studied. Results The vessel was initially free of any detectable lesions, but a 60% diameter reducing stenosis developed over the 16 month interval of study. As determined from the simulations, chaotic and recirculating flow occurred downstream of the stenosis due to the sudden widening of the lumen at the patch location. Curvature and a sudden increase in the lumen cross-sectional area induce these flow features that are hypothesized to be conducive to intimal hyperplasia. Favorable agreement was found between simulation results and in vivo Doppler ultrasound velocity measurements. Conclusions Transitional and chaotic flow occurs at the site of the revision, inducing a complex pattern of wall shear are computed with the hemodynamic simulations. This supports the hypothesis that the hemodynamic stresses in the revised segment, produced by the coupling of vessel geometry and chaotic flow, led to the intimal hyperplasia and restenosis of the graft. PMID:22551907

  8. The optimal hemodynamics management of post-cardiac arrest shock.

    PubMed

    Pellis, Tommaso; Sanfilippo, Filippo; Ristagno, Giuseppe

    2015-12-01

    Patients resuscitated from cardiac arrest develop a pathophysiological state named "post-cardiac arrest syndrome." Post-resuscitation myocardial dysfunction is a common feature of this syndrome, and many patients eventually die from cardiovascular failure. Cardiogenic shock accounts for most deaths in the first 3 days, when post-resuscitation myocardial dysfunction peaks. Thus, identification and treatment of cardiovascular failure is one of the key therapeutic goals during hospitalization of post-cardiac arrest patients. Patients with hemodynamic instability may require advanced cardiac output monitoring. Inotropes and vasopressors should be considered if hemodynamic goals are not achieved despite optimized preload. If these measures fail to restore adequate organ perfusion, a mechanical circulatory assistance device may be considered. Adequate organ perfusion should be ensured in the absence of definitive data on the optimal target pressure goals. Hemodynamic goals should also take into account targeted temperature management and its effect on the cardiovascular function.

  9. A Revised Hemodynamic Theory of Age-Related Macular Degeneration.

    PubMed

    Gelfand, Bradley D; Ambati, Jayakrishna

    2016-08-01

    Age-related macular degeneration (AMD) afflicts one out of every 40 individuals worldwide, causing irreversible central blindness in millions. The transformation of various tissue layers within the macula in the retina has led to competing conceptual models of the molecular pathways, cell types, and tissues responsible for the onset and progression of AMD. A model that has persisted for over 6 decades is the hemodynamic, or vascular theory of AMD progression, which states that vascular dysfunction of the choroid underlies AMD pathogenesis. Here, we re-evaluate this hypothesis in light of recent advances on molecular, anatomic, and hemodynamic changes underlying choroidal dysfunction in AMD. We propose an updated, detailed model of hemodynamic dysfunction as a mechanism of AMD development and progression. PMID:27423265

  10. Evaluation of bioimpedance for the measurement of physiologic variables as related to hemodynamic studies in space flight

    NASA Technical Reports Server (NTRS)

    Taylor, Bruce C.

    1993-01-01

    Orthostatic intolerance, following space flight, has received substantial attention because of the possibility that it compromises astronaut safety and reduces the ability of astronauts to function at peak performance levels upon return to a one-g environment. Many pre- and post-flight studies are performed to evaluate changes in hemodynamic responses to orthostatic challenges after shuttle missions. The purpose of this present project is to validate bioimpedance as a means to acquire stroke volume and other hemodynamic information in these studies. In this study, ten male and ten female subjects were subjected to simultaneous measurements of thoracic bioimpedance and Doppler ultrasonic velocimetry under supine, 10 degree head down and 30 degree head up conditions. Paired measurements were made during six periods of five seconds breath holding, over a two minute period, for each of the three positions. Stroke volume was calculated by three bioimpedance techniques and ultrasonic Doppler.

  11. Physical Activity and Hemodynamic Reactivity in Chronic Kidney Disease

    PubMed Central

    Agarwal, Rajiv; Light, Robert P.

    2008-01-01

    Background and objectives: Patients with chronic kidney disease (CKD) have an elevated cardiovascular risk. This study was designed to understand better the presence and strength of the relationship between physical activity and BP and to explore determinants of hemodynamic reactivity. Design, setting, participants, & measurements: Twenty-four patients with CKD (mean age 69.5 yr; 3.1 antihypertensive drugs; estimated GFR 47 ml/min per 1.73 m2, albumin/creatinine ratio 403 mg/g) were studied on three occasions during a 6-wk period with 24-h ambulatory BP monitoring and simultaneous activity monitoring with wrist actigraphy. Results: Nondippers were found have a greater level of sleep activity compared with dippers, although the awake activity level was similar (7.06 versus 6.73) between groups (P = 0.042 for interaction). In 3587 BP activity pairs, hemodynamic reactivity was variable between individuals (systolic BP reactivity 1.06 [SD 10.50]; diastolic BP reactivity 0.89 [SD 7.80] heart rate reactivity 1.18 [SD 11.00]); those who were more sedentary had a greater increment in systolic BP compared with those who were less sedentary. Antihypertensive drugs blunted hemodynamic reactivity. Hemodynamic reactivity was greatest between 12 a.m. and 8 a.m., making this a vulnerable period for cardiovascular events. Conclusions: Greater hemodynamic reactivity in sedentary people with CKD offers a possible and thus far unrecognized mechanism of cardiovascular damage. Besides reducing BP, antihypertensive drugs reduce hemodynamic reactivity, which offers another plausible mechanism of cardiovascular protection with their use. PMID:18922983

  12. Monitoring of Systemic and Hepatic Hemodynamic Parameters in Mice

    PubMed Central

    Xie, Chichi; Wei, Weiwei; Zhang, Tao; Dirsch, Olaf; Dahmen, Uta

    2014-01-01

    The use of mouse models in experimental research is of enormous importance for the study of hepatic physiology and pathophysiological disturbances. However, due to the small size of the mouse, technical details of the intraoperative monitoring procedure suitable for the mouse were rarely described. Previously we have reported a monitoring procedure to obtain hemodynamic parameters for rats. Now, we adapted the procedure to acquire systemic and hepatic hemodynamic parameters in mice, a species ten-fold smaller than rats. This film demonstrates the instrumentation of the animals as well as the data acquisition process needed to assess systemic and hepatic hemodynamics in mice. Vital parameters, including body temperature, respiratory rate and heart rate were recorded throughout the whole procedure. Systemic hemodynamic parameters consist of carotid artery pressure (CAP) and central venous pressure (CVP). Hepatic perfusion parameters include portal vein pressure (PVP), portal flow rate as well as the flow rate of the common hepatic artery (table 1). Instrumentation and data acquisition to record the normal values was completed within 1.5 h. Systemic and hepatic hemodynamic parameters remained within normal ranges during this procedure. This procedure is challenging but feasible. We have already applied this procedure to assess hepatic hemodynamics in normal mice as well as during 70% partial hepatectomy and in liver lobe clamping experiments. Mean PVP after resection (n= 20), was 11.41±2.94 cmH2O which was significantly higher (P<0.05) than before resection (6.87±2.39 cmH2O). The results of liver lobe clamping experiment indicated that this monitoring procedure is sensitive and suitable for detecting small changes in portal pressure and portal flow rate. In conclusion, this procedure is reliable in the hands of an experienced micro-surgeon but should be limited to experiments where mice are absolutely needed. PMID:25350047

  13. Body position does not affect the hemodynamic response to venous air embolism in dogs

    NASA Technical Reports Server (NTRS)

    Mehlhorn, U.; Burke, E. J.; Butler, B. D.; Davis, K. L.; Katz, J.; Melamed, E.; Morris, W. P.; Allen, S. J.

    1994-01-01

    Current therapy for massive venous air embolism (VAE) includes the use of the left lateral recumbent (LLR) position. This recommendation is based on animal studies, conducted 50 yr ago, which looked primarily at survival. Little is known, however, about the concomitant hemodynamic response after VAE in various body positions. The purpose of this study was to investigate the hemodynamic and cardiovascular changes in various body positions after VAE. Twenty-two mechanically ventilated supine mongrel dogs received a venous air infusion of 2.5 mL/kg at a rate of 5 mL/s. One minute after the infusion, 100% oxygen ventilation was commenced and the body position of the dogs was changed to either the LLR (n = 6), the LLR with the head 10 degrees down (LLR-10 degrees; n = 6) or the right lateral recumbent (RLR; n = 5) position. Five dogs were maintained in the supine position (SUP; n = 5). One dog died in every group except in the SUP group, where all the dogs recovered. There were no significant differences among the various body positions in terms of heart rate, mean arterial pressure, pulmonary artery pressure, central venous pressure, left ventricular end-diastolic pressure, or cardiac output. The acute hemodynamic changes occurring during the first 5-15 min after VAE recovered to 80% of control within 60 min. Our data suggest that body repositioning does not influence the cardiovascular response to VAE. Specifically, our data do not support the recommendation of repositioning into the LLR position for the treatment of VAE.

  14. Body position does not affect the hemodynamic response to venous air embolism in dogs

    NASA Technical Reports Server (NTRS)

    Mehlhorn, Uwe; Burke, Edward J.; Butler, Bruce D.; Davis, Karen L.; Katz, Jeffrey; Melamed, Evan; Morris, William P.; Allen, Steven J.

    1993-01-01

    Current therapy for massive venous air embolism (VAE) includes the use of the left lateral recumbent (LLR) position. This recommendation is based on animal studies, conducted 50 years ago, which looked primarily at survival. Little is known, however, about the concomitant hemodynamic response after VAE in various body positions. The purpose of this study was to investigate the hemodynamic and cardiovascular changes in various body positions after VAE. Twenty-two mechanically ventilated supine mongrel dogs received a venous air infusion of 2.5 mL/kg at a rate of 5 mL/s. One minute after the infusion, 100% oxygen ventilation was commenced and the body position of the dogs was changed to either the LLR (n = 6), the LLR with the head 10 deg down (LLR-10 deg; n = 6) or the right lateral recumbent (RLR; n = 5) position. Five dogs were maintained in the supine position (SUP; n = 5). One dog died in every group except in the SUP group, where all the dogs recovered. There were no significant differences among the various body positions in terms of heart rate, mean arterial pressure, pulmonary artery pressure, central venous pressure, left ventricular end-diastolic pressure, or cardiac output. The acute hemodynamic changes occurring during the first 5-15 min after VAE recovered to 80% of control within 60 min. Our data suggest that body repositioning does not influence the cardiovascular response to VAE. Specifically, our data do not support the recommendation of repositioning into the LLR position for the treatment of VAE.

  15. Morphometric and hemodynamic analysis of atherosclerotic progression in human carotid artery bifurcations.

    PubMed

    Huang, Xu; Yin, Xiaoping; Xu, Yingjin; Jia, Xinwei; Li, Jianhui; Niu, Pei; Shen, Wenzeng; Kassab, Ghassan S; Tan, Wenchang; Huo, Yunlong

    2016-03-01

    Although atherosclerosis has been widely investigated at carotid artery bifurcation, there is a lack of morphometric and hemodynamic data at different stages of the disease. The purpose of this study was to determine the lesion difference in patients with carotid artery disease compared with healthy control subjects. The three-dimensional (3D) geometry of carotid artery bifurcation was reconstructed from computed tomography angiography (CTA) images of Chinese control subjects (n = 30) and patients with carotid artery disease (n = 30). We defined two novel vector angles (i.e., angles 1 and 2) that were tangential to the reconstructed contour of the 3D vessel. The best-fit diameter was computed along the internal carotid artery (ICA) center line. Hemodynamic analysis was performed at various bifurcations. Patients with stenotic vessels have larger angles 1 and 2 (151 ± 11° and 42 ± 20°) and smaller diameters of the external carotid artery (ECA) (4.6 ± 0.85 mm) compared with control subjects (144 ± 13° and 36 ± 16°, 5.2 ± 0.57 mm) although there is no significant difference in the common carotid artery (CCA) (7.1 ± 1.2 vs. 7.5 ± 1.0 mm, P = 0.18). In particular, all patients with carotid artery disease have a stenosis at the proximal ICA (including both sinus and carina regions), while 20% of patients have stenosis at the middle ICA and 20% have stenosis expansion to the entire cervical ICA. Morphometric and hemodynamic analyses suggest that atherosclerotic plaques initiate at both sinus and carina regions of ICA and progress downstream.

  16. Limb movement-induced hyperemia has a central hemodynamic component: evidence from a neural blockade study

    PubMed Central

    Amann, Markus; McDaniel, John; Fjeldstad, Anette S.; Barrett-O'Keefe, Zachary; Runnels, Sean; Morgan, David E.; Wray, D. Walter; Richardson, Russell S.

    2010-01-01

    The purpose of this investigation was to partially remove feedback from type III/IV skeletal muscle afferents and determine how this feedback influences the central and peripheral hemodynamic responses to passive leg movement. Heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure, leg vascular conductance (LVC), and leg blood flow (LBF) were measured during 2 min of passive knee extension in eight young men before and after intrathecal fentanyl injection. Passive movement increased HR by 14 beats/min from baseline to maximal response during control (CON) (65 ± 4 to 79 ± 5 beats/min, P < 0.05), whereas HR did not significantly increase with the fentanyl block (BLK). LBF and LVC increased in both conditions; however, these increases were attenuated and delayed during BLK [%change from baseline to maximum, LBF: CON 295 ± 109 vs. BLK 210 ± 86%, (P < 0.05); LVC: CON 322 ± 40% vs. BLK 231 ± 32%, (P < 0.04)]. In CON, HR, SV, CO, and LVC increased contributing to the hyperemic response. However, under BLK conditions, statistically insignificant increases in HR and SV combined to yield a small, but significant, increase in CO and an attenuated hyperemic response. Therefore, partially blocking skeletal muscle afferent feedback blunts the central hemodynamic response due to passive limb movement, which then results in an attenuated and delayed movement-induced hyperemia. In combination, these findings provide evidence that limb movement-induced hyperemia has a significant central hemodynamic component induced by peripheral nerve activation. PMID:20802133

  17. Measuring cerebral hemodynamic changes during action observation with functional transcranial doppler

    PubMed Central

    Kim, Seong-Sik; Lee, Byoung-Hee

    2015-01-01

    [Purpose] The purpose of this study was to investigate the effects of action observation training (AOT) on cerebral hemodynamic changes including cerebral blood flow velocity (CBFV) and cerebral blood flow volume (CBFvol) in healthy subjects. [Subjects] Fifteen healthy subjects participated in this study. [Methods] All subjects were educated regarding AOT, and systolic peak velocity (Vs) as well as mean flow velocity (Vm) in the middle cerebral artery (MCA), anterior cerebral artery (ACA), and posterior cerebral artery (PCA) were evaluated using functional transcranial doppler with a 2-MHz probe, before and after performing AOT. [Results] Healthy subjects showed significant differences in Vs and Vm in the MCA, ACA, and PCA after AOT compared with those before AOT. [Conclusion] Our findings indicate that AOT has a positive effect in terms of an increase in CBFV and CBFvol in healthy subjects, since the brain requires more blood to meet the metabolic demand during AOT. PMID:26157224

  18. Hemodynamic monitoring in the era of digital health.

    PubMed

    Michard, Frederic

    2016-12-01

    Digital innovations are changing medicine, and hemodynamic monitoring will not be an exception. Five to ten years from now, we can envision a world where clinicians will learn hemodynamics with simulators and serious games, will monitor patients with wearable or implantable sensors in the hospital and after discharge, will use medical devices able to communicate and integrate the historical, clinical, physiologic and biological information necessary to predict adverse events, propose the most rationale therapy and ensure it is delivered properly. Considerable intellectual and financial investments are currently made to ensure some of these new ideas and products soon become a reality. PMID:26885656

  19. Ultrasonic Imaging of Hemodynamic Force in Carotid Blood Flow

    NASA Astrophysics Data System (ADS)

    Nitta, N.; Homma, K.

    Hemodynamic forces including blood pressure and shear stress affect vulnerable plaque rupture in arteriosclerosis and biochemical activation of endothelium such as NO production. In this study, a method for estimating and imaging shear stress and pressure gradient distributions in blood vessel as the hemodynamic force based on viscosity estimation is presented. Feasibility of this method was investigated by applying to human carotid blood flow. Estimated results of shear stress and pressure gradient distributions coincide with the ideal distributions obtained by numerical simulation and flow-phantom experiment.

  20. Acute hemodynamic response to weightlessness during parabolic flight

    NASA Technical Reports Server (NTRS)

    Mukai, Chiaki N.; Lathers, Claire M.; Charles, John B.; Bennett, Barbara S.; Igarashi, Makoto; Patel, Saumil

    1991-01-01

    The effect of a short exposure to weightlessness on hemodynamic parameters of humans was investigated in seven subjects flown aboard the KC-135 aircraft. Particular attention is given to the relationships among various hemodynamic responses to hypergravic and hypogravic states, observed for four different postures: semisupine, supine, standing, and sitting. Results are presented on changes in the thoracic fluid index, heart rate, cardiac index, and the coefficient of variation of the R-R intervals. High values of the coefficient of variation were found at the onset of 0-G, suggesting that vagal cardiac neural activity increases in all positions except supine (where a small decrease was registered).

  1. Ischemia and reperfusion injury in renal transplantation: hemodynamic and immunological paradigms

    PubMed Central

    Requião-Moura, Lúcio Roberto; Durão, Marcelino de Souza; de Matos, Ana Cristina Carvalho; Pacheco-Silva, Alvaro

    2015-01-01

    Ischemia and reperfusion injury is an inevitable event in renal transplantation. The most important consequences are delayed graft function, longer length of stay, higher hospital costs, high risk of acute rejection, and negative impact of long-term follow-up. Currently, many factors are involved in their pathophysiology and could be classified into two different paradigms for education purposes: hemodynamic and immune. The hemodynamic paradigm is described as the reduction of oxygen delivery due to blood flow interruption, involving many hormone systems, and oxygen-free radicals produced after reperfusion. The immune paradigm has been recently described and involves immune system cells, especially T cells, with a central role in this injury. According to these concepts, new strategies to prevent ischemia and reperfusion injury have been studied, particularly the more physiological forms of storing the kidney, such as the pump machine and the use of antilymphocyte antibody therapy before reperfusion. Pump machine perfusion reduces delayed graft function prevalence and length of stay at hospital, and increases long-term graft survival. The use of antilymphocyte antibody therapy before reperfusion, such as Thymoglobulin™, can reduce the prevalence of delayed graft function and chronic graft dysfunction. PMID:25993079

  2. Telemetric Catheter-Based Pressure Sensor for Hemodynamic Monitoring: Experimental Experience

    SciTech Connect

    Mahnken, Andreas H.; Urban, Ute; Fassbender, Holger; Schnakenberg, Uwe; Schoth, Felix; Schmitz-Rode, Thomas

    2009-07-15

    The purpose of this study was to evaluate the technical and animal experimental feasibility of a percutaneously implantable pulmonary arterial implant for permanent hemodynamic monitoring. Two systems for measuring pulmonary artery pressure (PAP) as well as pulmonary artery occlusion pressure (PAOP) were developed by modifying a commercially available pulmonary artery catheter (PAC). First, a cable-bound catheter-based system was designed by implementation of a capacitive absolute-pressure sensor in the catheter tip. This system was developed further into a completely implantable telemetric system. The devices were tested in an acute setting in a total of 10 sheep. The implant was placed with its tip in the descending pulmonary artery via the right jugular approach. Results were compared with conventional PAC positioned in the contralateral pulmonary artery using Pearson's correlation coefficients and Bland-Altman plots. Implantation of the monitoring systems was uneventful in 10 animals. Data from two fully functional cable-bound and telemetric pressure monitoring systems were available, with a total of 18,506 measurements. There was an excellent correlation between reference data and the data obtained with the implants (r = 0.9944). Bland-Altman plots indicated a very good agreement between the techniques. We report the development and successful initial test of an implantable catheter-based device for long-term measurement of PAP and PAOP. Both devices may be applicable for hemodynamic monitoring. Further long-term studies for assessing reliability and durability of the device are warranted.

  3. From Unicuspid to Quadricuspid: Influence of Aortic Valve Morphology on Aortic 3D Hemodynamics

    PubMed Central

    Entezari, Pegah; Schnell, Susanne; Mahadevia, Riti; Malaisrie, Chris; McCarthy, Patrick; Mendelson, Marla; Collins, Jeremy; Carr, James C.; Markl, Michael; Barker, Alex J.

    2016-01-01

    Purpose To assess the impact of aortic valve morphology on aortic hemodynamicsbetweennormal tricuspid and congenitally anomalous aortic valvesranging from unicuspid to quadricuspid morphology. Materials and Methods Aortic 3D blood flow was evaluated by 4D flow MRI in 14 healthy volunteers with normal trileaflet valves and 14 patients withunicuspid(n=3), bicuspid (n=9, 3 ‘true’ bicuspid, 3 right-left (RL), 3 right-non (RN) coronary leaflet fusion, and quadricuspid aortic valves (n=2). Data analysis included the co-registered visualization of aortic valve morphology with systolic 3D blood flow. The influence of valve morphology on aortic hemodynamics was quantified by valve flow angle. Results All RL-BAV were associated with flow jets directed towards the right anterior aortic wallwhile RN-fusion and unicuspid valves resulted in flow jet patterns towards the right-posterior or posterior wall. Flow angles were clearly influenced by valve morphology(47°±10, 28°±2, 29°±18, 18°±12, 15°±2 for unicuspid, trueBAV, RN-BAV, RL-BAV, quadricuspid valves) and increased compared to controls (7.2°±1.1, p=0.001). Conclusions Altered 3D aortic hemodynamics are impacted by the morphology of congenitally malformed aortic valves. PMID:24265266

  4. Computational hemodynamic study of intracranial aneurysms coexistent with proximal artery stenosis

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Peloc, Nora L.; Putman, Christopher M.; Cebral, Juan R.

    2012-03-01

    Intracranial aneurysms and artery stenosis are vascular diseases with different pathophysiological characteristics. However, although unusual, aneurysms may coexist in up to 5% of patients with stenotic plaque, according to a previous study. Another study showed that incidental detection of cerebral aneurysm in the same cerebral circulation as the stenotic plaque was less than 2%. Patients with concomitant carotid artery stenosis and unruptured intracranial aneurysms pose a difficult management decision for the physician. Case reports showed patients who died due to aneurysm rupture months after endarterectomy but before aneurysm clipping, while others did not show any change in the aneurysm after plaque removal, having optimum outcome after aneurysm coiling. The purpose of this study is to investigate the intraaneurysmal hemodynamic changes before and after treatment of stenotic plaque. Idealized models were constructed with different stenotic grade, distance and relative position to the aneurysm. Digital removal of the stenotic plaque was performed in the reconstructed model of a patient with both pathologies. Computational fluid dynamic simulations were performed using a finite element method approach. Blood velocity field and hemodynamic forces were recorded and analyzed. Changes in the flow patterns and wall shear stress values and distributions were observed in both ideal and image-based models. Detailed investigation of wall shear stress distributions in patients with both pathologies is required to make the best management decision.

  5. Hemodynamic and cellular response feedback in calcific aortic valve disease.

    PubMed

    Gould, Sarah T; Srigunapalan, Suthan; Simmons, Craig A; Anseth, Kristi S

    2013-07-01

    This review highlights aspects of calcific aortic valve disease that encompass the entire range of aortic valve disease progression from initial cellular changes to aortic valve sclerosis and stenosis, which can be initiated by changes in blood flow (hemodynamics) and pressure across the aortic valve. Appropriate hemodynamics is important for normal valve function and maintenance, but pathological blood velocities and pressure can have profound consequences at the macroscopic to microscopic scales. At the macroscopic scale, hemodynamic forces impart shear stresses on the surface of the valve leaflets and cause deformation of the leaflet tissue. As discussed in this review, these macroscale forces are transduced to the microscale, where they influence the functions of the valvular endothelial cells that line the leaflet surface and the valvular interstitial cells that populate the valve extracellular matrix. For example, pathological changes in blood flow-induced shear stress can cause dysfunction, impairing their homeostatic functions, and pathological stretching of valve tissue caused by elevated transvalvular pressure can activate valvular interstitial cells and latent paracrine signaling cytokines (eg, transforming growth factor-β1) to promote maladaptive tissue remodeling. Collectively, these coordinated and complex interactions adversely impact bulk valve tissue properties, feeding back to further deteriorate valve function and propagate valve cell pathological responses. Here, we review the role of hemodynamic forces in calcific aortic valve disease initiation and progression, with focus on cellular responses and how they feed back to exacerbate aortic valve dysfunction.

  6. Measuring cerebral hemodynamics with a modified magnetoencephalography system.

    PubMed

    Burke, Broc A; Diamond, Solomon G

    2012-12-01

    Magnetoencephalography (MEG) systems are designed to noninvasively measure magnetic fields produced by neural electrical currents. This project examines the possibility of measuring hemodynamics with an MEG system that has been modified with dc electromagnets to measure magnetic susceptibility while maintaining the capability of measuring neural dynamics. A forward model is presented that simulates the interaction of an applied magnetic field with changes in magnetic susceptibility in the brain associated with hemodynamics. Model predictions are compared with an experiment where deionized water was pumped into an inverted flask under the MEG sensor array of superconducting quantum interference device (SQUID) gradiometers (R(2) = 0.98, p < 0.001). The forward model was used to simulate the SQUID readouts from hemodynamics in the scalp and brain induced by performing the Valsalva maneuver. Experimental human subject recordings (N = 10) were made from the prefrontal region during Valsalva using concurrent measurement with the modified MEG system and near-infrared spectroscopy (NIRS). The NIRS deoxyhemoglobin signal was found to correlate significantly with the SQUID readouts (R(2) = 0.84, p < 0.01). SQUID noise was found to increase with the applied field, which will need to be mitigated in future work. These results demonstrate the potential and technical challenges of measuring cerebral hemodynamics with a modified MEG system.

  7. Dietary melatonin alters uterine artery hemodynamics in pregnant holstein heifers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to examine uterine artery hemodynamics and maternal serum profiles in pregnant heifers supplemented with dietary melatonin (MEL) or no supplementation (CON). In addition, melatonin receptor–mediated responses in steroid metabolism were examined using a bovine endometrial epithelial...

  8. Hemodynamic alterations in chronically conscious unrestrained diabetic rats

    SciTech Connect

    Carbonell, L.F.; Salmon, M.G.; Garcia-Estan, J.; Salazar, F.J.; Ubeda, M.; Quesada, T.

    1987-05-01

    Important cardiovascular dysfunctions have been described in streptozotocin (STZ)-diabetic rats. To determine the influence of these changes on the hemodynamic state and whether insulin treatment can avoid them, different hemodynamic parameters, obtained by the thermodilution method, were studied in STZ-induced (65 mg/kg) diabetic male Wistar rats, as well as in age-control, weight-control, and insulin-treated diabetic ones. Plasma volume was measured by dilution of radioiodinated (/sup 125/I) human serum albumin. All rats were examined in the conscious, unrestrained state 12 wk after induction of diabetes or acidified saline (pH 4.5) injection. At 12 wk of diabetic state most important findings were normotension, high blood volume, bradycardia, increase in stroke volume, cardiac output, and cardiosomatic ratio, and decrease in total peripheral resistance and cardiac contractility and relaxation (dP/dt/sub max/ and dP/dt/sub min/ of left ventricular pressure curves). The insulin-treated diabetic rats did not show any hemodynamic differences when compared with the control animals. These results suggest that important hemodynamic alterations are present in the chronic diabetic states, possibly conditioning congestive heart failure. These alterations can be prevented by insulin treatment.

  9. [Hemodynamic repercussion of epidural bupivacaine in thoracic injuries].

    PubMed

    Pérez Gallardo, A; Lajara Montell, A M; Manzanos Luna, A M

    1991-01-01

    Systemic and pulmonary hemodynamic effects of 8 to 10 ml of 0.25% bupivacaine containing 1:200,000 adrenaline administered at the midthoracic level were prospectively assessed in 20 patients (aged 45 +/- 16 years) with thoracic trauma presenting 6 +/- 2 rib fractures and pulmonary contusion of different extent and radiologic density. The study was carried out at comparable evolving times, 24 h after trauma, during the second or third day of treatment, and when the hemodynamic stability of the patient was achieved. Hemodynamic measurements were performed before and 30 min after administration of the analgesic agent using a Swan-Ganz catheter. The results indicate that administration of moderate doses of epidural bupivacaine at the middle thoracic level in patients with normovolemic thoracic traumatism were not followed by alterations in the hemodynamic function except for a slight decrease in systemic arterial and pulmonary pressure. The mean arterial pressure decreased by 8% (p less than 0.05), the cardiac index showed a 4% reduction (p = 0.05), and the mean pulmonary pressure experienced a 14% decrease (p less than 0.05).

  10. Central hemodynamics and target organ damage in hypertension.

    PubMed

    Hashimoto, Junichiro

    2014-01-01

    Recent advances in technology have enabled the noninvasive evaluation of pulsatile hemodynamics in the central aorta; namely, central pressure and flow measurements. The central blood pressure represents the true load imposed on the heart, kidney and brain, and the central blood flow influences the local flow into these vital organs. An elevation of the central blood pressure has a direct, adverse impact on the target organ and, thus, the cardiovascular prognosis in patients with hypertension. A decrease in the central blood flow can cause organ dysfunction and failure. The central pressure and flow dynamics were conventionally regarded as unidirectional from the heart to the periphery. However, current evidence suggests that it should be recognized as a bidirectional interplay between the central and peripheral arteries. Specifically, the pressure pulse wave is not only transmitted forward to the periphery but also reflected backward to the central aorta. The flow pulse wave is also composed of the forward and reverse components. Aortic stiffening and arteriolar remodeling due to hypertension not only augment the central pressure by increasing the wave reflection but also may alter the central bidirectional flow, inducing hemodynamic damage/dysfunction in susceptible organs. Therefore, central hemodynamic monitoring has the potential to provide a diagnostic and therapeutic basis for preventing systemic target organ damage and for offering personalized therapy suitable for the arterial properties in each patient with hypertension. This brief review will summarize hypothetical mechanisms for the association between the central hemodynamics and hypertensive organ damage in the heart, kidney and brain.

  11. Central circulatory hemodynamics as a function of gravitational stress

    NASA Technical Reports Server (NTRS)

    Latham, Rick D.; White, C. D.; Fanton, J. W.; Owens, R. W.; Barber, J. F.; Lewkowski, B. E.; Goff, O. T.

    1991-01-01

    This study focuses on an evaluation of the central hemodynamics in a nonhuman primate model to variations in gravitational states. The baboon, phylogenectically close to man, was chosen as the human surrogate. The study environments selected are head-down and head-up tilt in the physiology laboratory, centrifugation to test hypergravic stress, and parabolic flights to test transient acute responses to microgravity.

  12. Elementary Hemodynamic Principles Based on Modified Bernoulli's Equation.

    ERIC Educational Resources Information Center

    Badeer, Henry S.

    1985-01-01

    Develops and expands basic concepts of Bernoulli's equation as it applies to vascular hemodynamics. Simple models are used to illustrate gravitational potential energy, steady nonturbulent flow, pump-driven streamline flow, and other areas. Relationships to the circulatory system are also discussed. (DH)

  13. Patient-specific analysis of post-operative aortic hemodynamics: a focus on thoracic endovascular repair (TEVAR)

    NASA Astrophysics Data System (ADS)

    Auricchio, F.; Conti, M.; Lefieux, A.; Morganti, S.; Reali, A.; Sardanelli, F.; Secchi, F.; Trimarchi, S.; Veneziani, A.

    2014-10-01

    The purpose of this study is to quantitatively evaluate the impact of endovascular repair on aortic hemodynamics. The study addresses the assessment of post-operative hemodynamic conditions of a real clinical case through patient-specific analysis, combining accurate medical image analysis and advanced computational fluid-dynamics (CFD). Although the main clinical concern was firstly directed to the endoluminal protrusion of the prosthesis, the CFD simulations have demonstrated that there are two other important areas where the local hemodynamics is impaired and a disturbed blood flow is present: the first one is the ostium of the subclavian artery, which is partially closed by the graft; the second one is the stenosis of the distal thoracic aorta. Besides the clinical relevance of these specific findings, this study highlights how CFD analyses allow to observe important flow effects resulting from the specific features of patient vessel geometries. Consequently, our results demonstrate the potential impact of computational biomechanics not only on the basic knowledge of physiopathology, but also on the clinical practice, thanks to a quantitative extraction of knowledge made possible by merging medical data and mathematical models.

  14. Transient AV Block as a Hemodynamic Complication of the Influenza A Virus: A Case Report.

    PubMed

    Rivera-Guzmán, Norwin; Del Olmo-Arroyo, Francisco; Robles-Arías, Carlos M; Rodríguez-Cintrón, William

    2016-09-01

    Influenza virus causes annual epidemics of respiratory illness characterized by sudden onset of fever, malaise, myalgias, headache, cough, and other respiratory complains. Each year in the United States, it is estimated that this debilitating respiratory illness accounts for 294,000 excess hospitalizations and 36,000 attributable deaths. Epidemiological studies describe increased cardiovascular mortality during influenza seasons. Cardiovascular involvement in acute influenza infection can occur through direct effects of the virus on the myocardium or through exacerbation of existing cardiovascular disease. The purpose of this report is to document a transient atrioventricular (AV) block with hemodynamic compromise after infection with the influenza virus in a patient with underlying cardiac disease without myocarditis. PMID:27623145

  15. Applicability of Pulse Pressure Variation during Unstable Hemodynamic Events in the Intensive Care Unit: A Five-Day Prospective Multicenter Study

    PubMed Central

    Delannoy, Bertrand; Wallet, Florent; Maucort-Boulch, Delphine; Page, Mathieu; Kaaki, Mahmoud; Schoeffler, Mathieu; Alexander, Brenton; Desebbe, Olivier

    2016-01-01

    Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting with an unstable hemodynamic event. The six predefined inclusion criteria for pulse pressure variation applicability were as follows: mechanical ventilation, tidal volume >7 mL/kg, sinus rhythm, no spontaneous breath, heart rate/respiratory rate ratio >3.6, absence of right ventricular dysfunction, or severe valvulopathy. Seventy-three patients presented at least one unstable hemodynamic event, with a total of 163 unstable hemodynamic events. The six predefined criteria for the applicability of pulse pressure variation were completely present in only 7% of these. This data indicates that PPV should only be used alongside a strong understanding of the relevant physiology and applicability criteria. Although these exclusion criteria appear to be profound, they likely represent an absolute contraindication of use for only a minority of critical care patients. PMID:27127648

  16. Hemodynamic-impact-based prioritization of ventricular tachycardia alarms.

    PubMed

    Desai, Kalpit; Lexa, Michael; Matthews, Brett; Genc, Sahika

    2014-01-01

    Ventricular tachycardia (V-tach) is a very serious condition that occurs when the ventricles are driven at high rates. The abnormal excitation pathways make ventricular contraction less synchronous resulting in less effective filling and emptying of the left ventricles. However, almost half of the V-tach alarms declared through processing of patterns observed in electrocardiography are not clinically actionable. The focus of this study is to provide guidance on determining whether a technically-correct V-tach alarm is clinically-actionable by determining its "hemodynamic impact". A supervisory learning approach based on conditional inference trees to determine the hemodynamic impact of a V-tach alarm based on extracted features is described. According to preliminary results on a subset of Multiparameter intelligent monitoring in intensive care II (MIMIC-II) database, true positive rate of more than 90% can be achieved. PMID:25570734

  17. Optimal control of CPR procedure using hemodynamic circulation model

    DOEpatents

    Lenhart, Suzanne M.; Protopopescu, Vladimir A.; Jung, Eunok

    2007-12-25

    A method for determining a chest pressure profile for cardiopulmonary resuscitation (CPR) includes the steps of representing a hemodynamic circulation model based on a plurality of difference equations for a patient, applying an optimal control (OC) algorithm to the circulation model, and determining a chest pressure profile. The chest pressure profile defines a timing pattern of externally applied pressure to a chest of the patient to maximize blood flow through the patient. A CPR device includes a chest compressor, a controller communicably connected to the chest compressor, and a computer communicably connected to the controller. The computer determines the chest pressure profile by applying an OC algorithm to a hemodynamic circulation model based on the plurality of difference equations.

  18. Cerebral venous hemodynamic abnormalities in episodic and chronic migraine

    PubMed Central

    Petolicchio, Barbara; Viganò, Alessandro; di Biase, Lazzaro; Tatulli, Doriana; Toscano, Massimiliano; Vicenzini, Edoardo; Passarelli, Francesco; Di Piero, Vittorio

    2016-01-01

    Summary Alterations of cerebral venous drainage have been demonstrated in chronic migraine (CM), suggesting that cerebral venous hemodynamic abnormalities (CVHAs) play a role in this condition. The aim of the present study was to look for a correlation between CM and CVHAs. We recruited 33 subjects suffering from CM with or without analgesic overuse, 29 episodic migraine (EM) patients with or without aura, and 21 healthy subjects as controls (HCs). CVHAs were evaluated by transcranial and extracranial echo-color Doppler evaluation of five venous hemodynamic parameters. CVHAs were significantly more frequent in the CM and EM patients than in the HCs. In the migraine patients, CVHAs were not correlated with clinical features. The significantly greater frequency of CVHAs observed in the migraineurs may reflect a possible relationship between migraine and these abnormalities. Prospective longitudinal studies are needed to investigate whether CVHAs have a role in the processes of migraine chronification. PMID:27358220

  19. [Central and regional hemodynamics in long space flights].

    PubMed

    Turchaninova, V F; Egorov, A D; Domracheva, M V

    1989-01-01

    This paper presents the results of studying central and regional hemodynamics in short-term (7 days) and long-term (65-237 days) space mission onboard Salyut-6--Soyuz and Salyut-7--Soyuz using the method of tetrapolar rheography. During space flights circulation changes were observed: variations in pulse blood filling and tone of regional vessels (head, forearm, leg) and insignificant changes of stroke volume and cardiac output. In response to exercise tests the contribution of stroke volume to cardiac output decreased and that of the chronotropic function of the heart increased. These changes were induced by variations in the hemodynamic status of the human body and were, to a certain extent, dependent on flight duration and position of the vascular area relative to the heart. The changes suggested that the circulation system retained its adaptive capabilities in flights of 237 days in duration.

  20. Pharmacological Modulation of Hemodynamics in Adult Zebrafish In Vivo

    PubMed Central

    Brönnimann, Daniel; Dellenbach, Christian; Saveljic, Igor; Rieger, Michael; Rohr, Stephan; Filipovic, Nenad; Djonov, Valentin

    2016-01-01

    Introduction Hemodynamic parameters in zebrafish receive increasing attention because of their important role in cardiovascular processes such as atherosclerosis, hematopoiesis, sprouting and intussusceptive angiogenesis. To study underlying mechanisms, the precise modulation of parameters like blood flow velocity or shear stress is centrally important. Questions related to blood flow have been addressed in the past in either embryonic or ex vivo-zebrafish models but little information is available for adult animals. Here we describe a pharmacological approach to modulate cardiac and hemodynamic parameters in adult zebrafish in vivo. Materials and Methods Adult zebrafish were paralyzed and orally perfused with salt water. The drugs isoprenaline and sodium nitroprusside were directly applied with the perfusate, thus closely resembling the preferred method for drug delivery in zebrafish, namely within the water. Drug effects on the heart and on blood flow in the submental vein were studied using electrocardiograms, in vivo-microscopy and mathematical flow simulations. Results Under control conditions, heart rate, blood flow velocity and shear stress varied less than ± 5%. Maximal chronotropic effects of isoprenaline were achieved at a concentration of 50 μmol/L, where it increased the heart rate by 22.6 ± 1.3% (n = 4; p < 0.0001). Blood flow velocity and shear stress in the submental vein were not significantly increased. Sodium nitroprusside at 1 mmol/L did not alter the heart rate but increased blood flow velocity by 110.46 ± 19.64% (p = 0.01) and shear stress by 117.96 ± 23.65% (n = 9; p = 0.03). Discussion In this study, we demonstrate that cardiac and hemodynamic parameters in adult zebrafish can be efficiently modulated by isoprenaline and sodium nitroprusside. Together with the suitability of the zebrafish for in vivo-microscopy and genetic modifications, the methodology described permits studying biological processes that are dependent on hemodynamic

  1. Altering hemodynamics leads to congenital heart defects (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ford, Stephanie M.; McPheeters, Matthew T.; Wang, Yves T.; Gu, Shi; Doughman, Yong Qiu; Strainic, James P.; Rollins, Andrew M.; Watanabe, Michiko; Jenkins, Michael W.

    2016-03-01

    The role of hemodynamics in early heart development is poorly understood. In order to successfully assess the impact of hemodynamics on development, we need to monitor and perturb blood flow, and quantify the resultant effects on morphology. Here, we have utilized cardiac optical pacing to create regurgitant flow in embryonic hearts and OCT to quantify regurgitation percentage and resultant morphology. Embryonic quail in a shell-less culture were optically paced at 3 Hz (well above the intrinsic rate or 1.33-1.67 Hz) on day 2 of development (3-4 weeks human) for 5 minutes. The pacing fatigued the heart and led to a prolonged period (> 1 hour) of increased regurgitant flow. Embryos were kept alive until day 3 (cardiac looping - 4-5 weeks human) or day 8 (4 chambered heart - 8 weeks human) to quantify resultant morphologic changes with OCT. All paced embryos imaged at day 3 displayed cardiac defects. The extent of regurgitant flow immediately after pacing was correlated with cardiac cushion size 24-hours post pacing (p-value < 0.01) with higher regurgitation leading to smaller cushions. Almost all embryos (16/18) surviving to day 8 exhibited congenital heart defects (CHDs) including 11/18 with valve defects, 5/18 with ventricular septal defects and 5/18 with hypoplastic right ventricles. Our data suggests that regurgitant flow leads to smaller cushions, which develop into abnormal valves and septa. Our model produces similar phenotypes as found in our fetal alcohol syndrome and velo-cardio-facial/DiGeorge syndrome models suggesting that hemodynamics plays a role in these syndromes as well. Utilizing OCT and optical pacing to understand hemodynamics in development is an important step towards determining CHD mechanisms and ultimately developing earlier treatments.

  2. Stenosis hemodynamics: from physical principles to clinical indices.

    PubMed

    Brown, Donald J; Smith, Francis W K

    2002-01-01

    Clinical evaluation of patients with aortic stenosis entails hemodynamic determinations and interpretations that depend on complex blood flow patterns. Although pressure gradient and Doppler velocity are intrinsically adjusted for a wide range of species and body size, they are highly flow-dependent indices that can vary among patients with physically identical stenosis areas and within individuals between determinations. Other indices, such as the Gorlin area, are adjusted for flow. All stenosis indices derived from hemodynamic measurements, however, must exhibit some degree of flow dependence because of fundamental aspects of fluid dynamics that affect the blood velocity profile. The Gorlin effective orifice area is an index that sacrifices adjustment for body size. This hinders comparisons over a range of patient species, breed, and size because it may be problematic to determine what effective orifice area is appropriate for a given individual. One potential solution is to compare the effective area of an individual's normal tract, if one exists, to the tract in question as a ratio, the effective orifice area ratio (EOAR). The EOAR can be estimated from the ratio of flow velocity integrals (FVIs) of the 2 outflow tracts. Clinical data and experience are lacking, but theoretical advantages of the index include intrinsic adjustment for both body size and flow rate. Aortic stenosis is a complex, multifactorial disease, and selection of an optimal hemodynamic severity index may not result in adequate prognostic criteria for segregation of patient risk and treatment groups.

  3. Hemodynamic Responses to Speech and Music in Preverbal Infants

    PubMed Central

    Fava, Eswen; Hull, Rachel; Baumbauer, Kyle; Bortfeld, Heather

    2013-01-01

    Numerous studies have provided clues about the ontogeny of lateralization of auditory processing in humans, but most have employed specific subtypes of stimuli and/or have assessed responses in discrete temporal windows. The present study used near-infrared spectroscopy (NIRS) to establish changes in hemodynamic activity in the neocortex of preverbal infants (aged 4-11 months) while they were exposed to two distinct types of complex auditory stimuli (full sentences and musical phrases). Measurements were taken from bilateral temporal regions, including both anterior and posterior superior temporal gyri. When the infant sample was treated as a homogenous group, no significant effects emerged for stimulus type. However, when infants' hemodynamic responses were categorized according to their overall changes in volume, two very clear neurophysiological patterns emerged. A high responder group, showed a pattern of early and increasing activation, primarily in the left hemisphere, similar to that observed in comparable studies with adults. In contrast, a low responder group showed a pattern of gradual decreases inactivation over time. Although age did track with responder type, no significant differences between these groups emerged for stimulus type, suggesting that the high versus low responder characterization generalizes across classes of auditory stimuli. These results highlight a new way to conceptualize the variable cortical blood flow patterns that are frequently observed across infants and stimuli, with hemodynamic response volumes potentially serving as an early indicator of developmental changes in auditory processing sensitivity. PMID:23777481

  4. Hemodynamic responses to speech and music in preverbal infants.

    PubMed

    Fava, Eswen; Hull, Rachel; Baumbauer, Kyle; Bortfeld, Heather

    2014-01-01

    Numerous studies have provided clues about the ontogeny of lateralization of auditory processing in humans, but most have employed specific subtypes of stimuli and/or have assessed responses in discrete temporal windows. The present study used near-infrared spectroscopy (NIRS) to establish changes in hemodynamic activity in the neocortex of preverbal infants (aged 4-11 months) while they were exposed to two distinct types of complex auditory stimuli (full sentences and musical phrases). Measurements were taken from bilateral temporal regions, including both anterior and posterior superior temporal gyri. When the infant sample was treated as a homogenous group, no significant effects emerged for stimulus type. However, when infants' hemodynamic responses were categorized according to their overall changes in volume, two very clear neurophysiological patterns emerged. A high-responder group showed a pattern of early and increasing activation, primarily in the left hemisphere, similar to that observed in comparable studies with adults. In contrast, a low-responder group showed a pattern of gradual decreases in activation over time. Although age did track with responder type, no significant differences between these groups emerged for stimulus type, suggesting that the high- versus low-responder characterization generalizes across classes of auditory stimuli. These results highlight a new way to conceptualize the variable cortical blood flow patterns that are frequently observed across infants and stimuli, with hemodynamic response volumes potentially serving as an early indicator of developmental changes in auditory-processing sensitivity.

  5. A study of the hemodynamics of anterior communicating artery aneurysms

    NASA Astrophysics Data System (ADS)

    Cebral, Juan R.; Castro, Marcelo A.; Putman, Christopher M.

    2006-03-01

    In this study, the effects of unequal physiologic flow conditions in the internal carotid arteries on the intra-aneurysmal hemodynamics of anterior communicating artery aneurysms were investigated. Patient-specific vascular computational fluid dynamics models of five cerebral aneurysms were constructed from bilateral 3D rotational angiography images. The aneurysmal hemodynamics was analyzed under a range of physiologic flow conditions including the effects of unequal mean flows and phase shifts between the flow waveforms of the left and right internal carotid arteries. A total of five simulations were performed for each patient, and unsteady wall shear stress (WSS) maps were created for each flow condition. Time dependent curves of average WSS magnitude over selected regions on the aneurysms were constructed and used to analyze the influence of the inflow conditions. It was found that mean flow imbalances in the feeding vessels tend to shift the regions of elevated WSS (flow impingement region) towards the dominating inflow jet and to change the magnitude of the WSS peaks. However, the overall qualitative appearance of the WSS distribution and velocity simulations is not substantially affected. In contrast, phase differences tend to increase the temporal complexity of the hemodynamic patterns and to destabilize the intra-aneurysmal flow pattern. However, these effects are less important when the A1 confluence is less symmetric, i.e. dominated by one of the A1 segments. Conditions affecting the flow characteristics in the parent arteries of cerebral aneurysms with more than one avenue of inflow should be incorporated into flow models.

  6. [Study on Indicator Densitometry Determination Method of Hemodynamic Parameters].

    PubMed

    Liu, Guang-da; Zhou, Run-dong; Zha, Yu-tong; Cai, Jing; Niu, Jun-qi; Gao, Pu-jun; Liu, Li-li

    2016-03-01

    Measurement for hemodynamic parameters has always been a hot spot of clinical research. Methods for measuring hemodynamic parameters clinically have the problems of invasiveness, complex operation and being unfit for repeated measurement. To solve the problems, an indicator densitometry analysis method is presented based on near-infrared spectroscopy (NIRS) and indicator dilution theory, which realizes the hemodynamic parameters measured noninvasively. While the indocyanine green (ICG) was injected into human body, circulation carried the indicator mixing and diluting with the bloodstream. Then the near-nfrared probe was used to emit near-infrared light at 735, 805 and 940 nm wavelengths through the sufferer's fingertip and synchronously capture the transmission light containing the information of arterial pulse wave. By uploading the measured data, the computer would calculate the ICG concentration, establish continuous concentration curve and compute some intermediate variables such as the mean transmission time (MTT) and the initial blood ICG concentration (c(t0)). Accordingly Cardiac Output (CO) and Circulating Blood Volume (CBV) could be calculated. Compared with the clinical "gold standard" methods of thermodilution and I-131 isotope-labelling method to measure the two parameters by clinical controlled trials, ten sets of data were obtained. The maximum relative errors of this method were 8.88% and 4.28% respectively, and both of the average relative errors were below 5%. The result indicates that this method can meet the clinical accuracy requirement and can be used as a noninvasive, repeatable and applied solution for clinical hemodynamnic parameters measurement. PMID:27400501

  7. Calf pump activity influencing venous hemodynamics in the lower extremity.

    PubMed

    Recek, Cestmir

    2013-03-01

    Calf muscle pump is the motive force enhancing return of venous blood from the lower extremity to the heart. It causes displacement of venous blood in both vertical and horizontal directions, generates ambulatory pressure gradient between thigh and lower leg veins, and bidirectional streaming within calf perforators. Ambulatory pressure gradient triggers venous reflux in incompetent veins, which induces ambulatory venous hypertension in the lower leg and foot. Bidirectional flow in calf perforators enables quick pressure equalization between deep and superficial veins of the lower leg; the outward (into the superficial veins) oriented component of the bidirectional flow taking place during calf muscle contraction is no pathological reflux but a physiological centripetal flow streaming via great saphenous vein into the femoral vein. Calf perforators are communicating channels between both systems making them conjoined vessels; they are not involved in the generation of pathological hemodynamic situations, nor do they cause ambulatory venous hypertension. The real cause why recurrences develop has not as yet been cleared. Pressure gradient arising during calf pump activity between the femoral vein and the saphenous remnant after abolition of saphenous reflux triggers biophysical and biochemical events, which might induce recurrence. Thus, abolition of saphenous reflux removes the hemodynamic disturbance, but at the same time it generates precondition for reflux recurrence and for the comeback of the previous pathological situation; this chain of events has been called hemodynamic paradox. PMID:24436580

  8. Hemodynamics in Coronary Arterial Tree of Serial Stenoses

    PubMed Central

    Lu, Bin; Jia, Xinwei; Zhong, Liang; Kassab, Ghassan S.; Tan, Wenchang

    2016-01-01

    Serial segmental narrowing frequently occurs in humans, which alters coronary hemodynamics and further affects atherosclerotic progression and plaque formation. The objective of this study was to understand the distribution of hemodynamic parameters in the epicardial left main coronary arterial (LMCA) tree with serial stenoses reconstructed from patient computer tomography angiography (CTA) images. A finite volume method was used in conjunction with the inlet pressure wave and outlet flow resistance. The time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI) were determined from the flow field. A stenosis at a mother vessel mainly deteriorated the hemodynamics near the bifurcation while a stenosis at a daughter vessel affected the remote downstream bifurcation. In comparison with a single stenosis, serial stenoses increased the peak pressure gradient along the main trunk of the epicardial left anterior descending arterial tree by > 50%. An increased distance between serial stenoses further increased the peak pressure gradient. These findings have important implications on the diagnosis and treatment of serial coronary stenoses. PMID:27685989

  9. Quantifying the abnormal hemodynamics of sickle cell anemia

    NASA Astrophysics Data System (ADS)

    Lei, Huan; Karniadakis, George

    2012-02-01

    Sickle red blood cells (SS-RBC) exhibit heterogeneous morphologies and abnormal hemodynamics in deoxygenated states. A multi-scale model for SS-RBC is developed based on the Dissipative Particle Dynamics (DPD) method. Different cell morphologies (sickle, granular, elongated shapes) typically observed in deoxygenated states are constructed and quantified by the Asphericity and Elliptical shape factors. The hemodynamics of SS-RBC suspensions is studied in both shear and pipe flow systems. The flow resistance obtained from both systems exhibits a larger value than the healthy blood flow due to the abnormal cell properties. Moreover, SS-RBCs exhibit abnormal adhesive interactions with both the vessel endothelium cells and the leukocytes. The effect of the abnormal adhesive interactions on the hemodynamics of sickle blood is investigated using the current model. It is found that both the SS-RBC - endothelium and the SS-RBC - leukocytes interactions, can potentially trigger the vicious ``sickling and entrapment'' cycles, resulting in vaso-occlusion phenomena widely observed in micro-circulation experiments.

  10. Dynamic cerebral autoregulation measured with coherent hemodynamics spectroscopy (CHS)

    NASA Astrophysics Data System (ADS)

    Kainerstorfer, Jana M.; Sassaroli, Angelo; Tgavalekos, Kristen T.; Fantini, Sergio

    2015-03-01

    Coherent Hemodynamics Spectroscopy (CHS) is a novel technique for non-invasive measurements of local microcirculation quantities such as the capillary blood transit times and dynamic autoregulation. The basis of CHS is to measure, for instance with near-infrared spectroscopy (NIRS), peripheral coherent hemodynamic changes that are induced by controlled perturbations in the systemic mean arterial pressure (MAP). In this study, the MAP perturbation was induced by the fast release of two pneumatic cuffs placed around the subject's thighs after they were kept inflated (at 200 mmHg) for two minutes. The resulting transient changes in cerebral oxy- (O) and deoxy- (D) hemoglobin concentrations measured with NIRS on the prefrontal cortex are then described by a novel hemodynamic model, from which quantifiable parameters such as the capillary blood transit time and a cutoff frequency for cerebral autoregulation are obtained. We present results on eleven healthy volunteers in a protocol involving measurements during normal breathing and during hyperventilation, which is known to cause a hypocapnia-induced increase in cerebral autoregulation. The measured capillary transit time was unaffected by hyperventilation (normal breathing: 1.1±0.1 s; hyperventilation: 1.1±0.1 s), whereas the cutoff frequency of autoregulation, which increases for higher autoregulation efficiency, was indeed found to be significantly greater during hyperventilation (normal breathing: 0.017±0.002 Hz; hyperventilation: 0.034±0.005 Hz). These results provide a validation of local cerebral autoregulation measurements with the new technique of CHS.

  11. Hemodynamics alter arterial low-density lipoprotein metabolism

    SciTech Connect

    Warty, V.S.; Calvo, W.J.; Berceli, S.A.; Pham, S.M.; Durham, S.J.; Tanksale, S.K.; Klein, E.C.; Herman, I.M.; Borovetz, H.S. )

    1989-10-01

    We have investigated the role of hemodynamic factors on low-density lipoprotein transport and metabolism in the intact arterial wall. Freshly excised canine carotid blood vessels were exposed to well-defined pulsatile flow in vitro for continuous periods up to 20 hours. We chose to impose the following hemodynamic conditions on our test carotid arteries: normotension, hypertension (at physiologic flow conditions), and hypertension coupled with elevated flow of canine serum perfusate. In several experiments the effect of endothelial denudation was examined in carotid arteries exposed to normotensive pulsatile flow. A trapped ligand method was used for quantitating low-density lipoprotein uptake and metabolism in the arterial wall. The distribution of both intact and degraded low-density lipoprotein fractions was determined from measurements of radiolabelled low-density lipoprotein activity within thin radial sections of perfused arteries. Our results suggest that both hypertensive hemodynamic simulations exacerbate the uptake of low-density lipoprotein within the arterial wall (by a factor of three to nine). The percentage of low-density lipoprotein that undergoes irreversible degradation falls from 41% under normotensive conditions to below 30% when hypertensive conditions are imposed, indicating that degradative processes are not proportionally elevated with the accelerated influx. A similar pattern is observed for deendothelialized vessels.

  12. Hemodynamics in an Aorta with Bicuspid and Trileaflet Valves

    NASA Astrophysics Data System (ADS)

    Gilmanov, Anvar; Sotiropoulos, Fotis

    2015-11-01

    Bicuspid aortic valve (BAV) is a congenital heart defect that has been associated with serious aortopathies, such as ascending aortic aneurysm, aortic stenosis, aortic regurgitation, infective endocarditis, aortic dissection, calcific aortic valve and dilatation of ascending aorta. Two main hypotheses - the genetic and the hemodynamic are discussed in literature to explain the development and progression of aortopathies in patients with BAV. In this study we seek to investigate the possible role of hemodynamic factors as causes of BAV-associated aortopathy. We employ the Curvilinear Immersed Boundary (CURVIB) method coupled with an efficient thin-shell finite element (TS-FE) formulation for tissues to carry out fluid-structure interaction simulations of a healthy tri-leaflet aortic valve (TAV) and a BAV placed in the same anatomic aorta. The computed results reveal major differences between the TAV and BAV flow patterns. These include: the dynamics of the aortic valve vortex ring formation and break up; the large scale flow patterns in the ascending aorta; and the shear stress magnitude on the aortic wall. The computed results are in qualitative agreement with in vivo Magnetic Resonance Imaging (MRI) data and suggest that the linkages between BAV aortopathy and hemodynamics deserve further investigation. This work is supported by the Lillehei Heart Institute at the University of Minnesota and the Minnesota Supercomputing Institute.

  13. Comparative hemodynamics in an aorta with bicuspid and trileaflet valves

    NASA Astrophysics Data System (ADS)

    Gilmanov, Anvar; Sotiropoulos, Fotis

    2016-04-01

    Bicuspid aortic valve (BAV) is a congenital heart defect that has been associated with serious aortopathies, such as aortic stenosis, aortic regurgitation, infective endocarditis, aortic dissection, calcific aortic valve and dilatation of ascending aorta. There are two main hypotheses to explain the increase prevalence of aortopathies in patients with BAV: the genetic and the hemodynamic. In this study, we seek to investigate the possible role of hemodynamic factors as causes of BAV-associated aortopathy. We employ the curvilinear immersed boundary method coupled with an efficient thin-shell finite-element formulation for tissues to carry out fluid-structure interaction simulations of a healthy trileaflet aortic valve (TAV) and a BAV placed in the same anatomic aorta. The computed results reveal major differences between the TAV and BAV flow patterns. These include: the dynamics of the aortic valve vortex ring formation and break up; the large-scale flow patterns in the ascending aorta; the shear stress magnitude, directions, and dynamics on the heart valve surfaces. The computed results are in qualitative agreement with in vivo magnetic resonance imaging data and suggest that the linkages between BAV aortopathy and hemodynamics deserve further investigation.

  14. Monitoring of hemodynamic changes induced in the healthy breast through inspired gas stimuli with MR-guided diffuse optical imaging

    PubMed Central

    Carpenter, C. M.; Rakow-Penner, R.; Jiang, S.; Pogue, B. W.; Glover, G. H.; Paulsen, K. D.

    2010-01-01

    Purpose: The modulation of tissue hemodynamics has important clinical value in medicine for both tumor diagnosis and therapy. As an oncological tool, increasing tissue oxygenation via modulation of inspired gas has been proposed as a method to improve cancer therapy and determine radiation sensitivity. As a radiological tool, inducing changes in tissue total hemoglobin may provide a means to detect and characterize malignant tumors by providing information about tissue vascular function. The ability to change and measure tissue hemoglobin and oxygenation concentrations in the healthy breast during administration of three different types of modulated gas stimuli (oxygen∕carbogen, air∕carbogen, and air∕oxygen) was investigated. Methods: Subjects breathed combinations of gases which were modulated in time. MR-guided diffuse optical tomography measured total hemoglobin and oxygen saturation in the breast every 30 s during the 16 min breathing stimulus. Metrics of maximum correlation and phase lag were calculated by cross correlating the measured hemodynamics with the stimulus. These results were compared to an air∕air control to determine the hemodynamic changes compared to the baseline physiology. Results: This study demonstrated that a gas stimulus consisting of alternating oxygen∕carbogen induced the largest and most robust hemodynamic response in healthy breast parenchyma relative to the changes that occurred during the breathing of room air. This stimulus caused increases in total hemoglobin and oxygen saturation during the carbogen phase of gas inhalation, and decreases during the oxygen phase. These findings are consistent with the theory that oxygen acts as a vasoconstrictor, while carbogen acts as a vasodilator. However, difficulties in inducing a consistent change in tissue hemoglobin and oxygenation were observed because of variability in intersubject physiology, especially during the air∕oxygen or air∕carbogen modulated breathing protocols

  15. Physiological responses to environmental factors related to space flight. [hemodynamic and metabolic responses to weightlessness

    NASA Technical Reports Server (NTRS)

    Pace, N.

    1973-01-01

    Physiological base line data are established, and physiological procedures and instrumentation necessary for the automatic measurement of hemodynamic and metabolic parameters during prolonged periods of weightlessness are developed.

  16. Flexible multivariate hemodynamics fMRI data analyses and simulations with PyHRF

    PubMed Central

    Vincent, Thomas; Badillo, Solveig; Risser, Laurent; Chaari, Lotfi; Bakhous, Christine; Forbes, Florence; Ciuciu, Philippe

    2014-01-01

    As part of fMRI data analysis, the pyhrf package provides a set of tools for addressing the two main issues involved in intra-subject fMRI data analysis: (1) the localization of cerebral regions that elicit evoked activity and (2) the estimation of activation dynamics also known as Hemodynamic Response Function (HRF) recovery. To tackle these two problems, pyhrf implements the Joint Detection-Estimation framework (JDE) which recovers parcel-level HRFs and embeds an adaptive spatio-temporal regularization scheme of activation maps. With respect to the sole detection issue (1), the classical voxelwise GLM procedure is also available through nipy, whereas Finite Impulse Response (FIR) and temporally regularized FIR models are concerned with HRF estimation (2) and are specifically implemented in pyhrf. Several parcellation tools are also integrated such as spatial and functional clustering. Parcellations may be used for spatial averaging prior to FIR/RFIR analysis or to specify the spatial support of the HRF estimates in the JDE approach. These analysis procedures can be applied either to volume-based data sets or to data projected onto the cortical surface. For validation purpose, this package is shipped with artificial and real fMRI data sets, which are used in this paper to compare the outcome of the different available approaches. The artificial fMRI data generator is also described to illustrate how to simulate different activation configurations, HRF shapes or nuisance components. To cope with the high computational needs for inference, pyhrf handles distributing computing by exploiting cluster units as well as multi-core machines. Finally, a dedicated viewer is presented, which handles n-dimensional images and provides suitable features to explore whole brain hemodynamics (time series, maps, ROI mask overlay). PMID:24782699

  17. Virtual angiography for visualization and validation of computational fluid dynamics models of aneurysm hemodynamics

    NASA Astrophysics Data System (ADS)

    Ford, Matthew D.; Stuhne, Gordan R.; Nikolov, Hristo N.; Lownie, Stephen P.; Holdsworth, David W.; Steinman, David A.

    2005-04-01

    It has recently become possible to simulate aneurysmal blood flow dynamics in a patient-specific manner via the coupling of 3D X-ray angiography and computational fluid dynamics (CFD). Before such image-based CFD models can be used in a predictive capacity, however, it must be shown that they indeed reproduce the in vivo hemodynamic environment. Motivated by the fact that there is currently no technique for measuring complex blood velocity fields in vivo, in this paper we describe how cine X-ray angiograms may be simulated for the purpose of indirectly validating patient-specific CFD models. Mirroring the radiological procedure, a virtual angiogram is constructed by first simulating the time-varying injection of contrast agent into a previously computed patient-specific CFD model. A time-series of images is then constructed by simulating attenuation of X-rays through the simulated 3D contrast-agent flow dynamics. Virtual angiographic images and residence time maps, here derived from an image-based CFD model of a giant aneurysm, are shown to be in excellent agreement with the corresponding clinical images and maps, but only when the interaction between the quasi-steady contrast-agent injection and the pulsatile wash-out are properly accounted for. These virtual angiographic techniques therefore pave the way for validating image-based CFD models against routinely available clinical data, and also provide a means of visualizing complex, 3D blood flow dynamics in a clinically relevant manner. However, they also clearly show how the contrast-agent injection perturbs the normal blood flow dynamics, further highlighting the utility of CFD as a window into the true aneurysmal hemodynamics.

  18. Calibrated MRI to evaluate cerebral hemodynamics in patients with an internal carotid artery occlusion

    PubMed Central

    De Vis, Jill B; Petersen, Esben T; Bhogal, Alex; Hartkamp, Nolan S; Klijn, Catharina JM; Kappelle, L J; Hendrikse, J

    2015-01-01

    The purpose of this study was to assess whether calibrated magnetic resonance imaging (MRI) can identify regional variances in cerebral hemodynamics caused by vascular disease. For this, arterial spin labeling (ASL)/blood oxygen level-dependent (BOLD) MRI was performed in 11 patients (65±7 years) and 14 controls (66±4 years). Cerebral blood flow (CBF), ASL cerebrovascular reactivity (CVR), BOLD CVR, oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2) were evaluated. The CBF was 34±5 and 36±11 mL/100 g per minute in the ipsilateral middle cerebral artery (MCA) territory of the patients and the controls. Arterial spin labeling CVR was 44±20 and 53±10% per 10 mm Hg ▵EtCO2 in patients and controls. The BOLD CVR was lower in the patients compared with the controls (1.3±0.8 versus 2.2±0.4% per 10 mm Hg ▵EtCO2, P<0.01). The OEF was 41±8% and 38±6%, and the CMRO2 was 116±39 and 111±40 μmol/100 g per minute in the patients and the controls. The BOLD CVR was lower in the ipsilateral than in the contralateral MCA territory of the patients (1.2±0.6 versus 1.6±0.5% per 10 mmHg ▵EtCO2, P<0.01). Analysis was hampered in three patients due to delayed arrival time. Thus, regional hemodynamic impairment was identified with calibrated MRI. Delayed arrival artifacts limited the interpretation of the images in some patients. PMID:25712500

  19. Optical imaging of neural and hemodynamic brain activity

    NASA Astrophysics Data System (ADS)

    Schei, Jennifer Lynn

    Optical imaging technologies can be used to record neural and hemodynamic activity. Neural activity elicits physiological changes that alter the optical tissue properties. Specifically, changes in polarized light are concomitant with neural depolarization. We measured polarization changes from an isolated lobster nerve during action potential propagation using both reflected and transmitted light. In transmission mode, polarization changes were largest throughout the center of the nerve, suggesting that most of the optical signal arose from the inner nerve bundle. In reflection mode, polarization changes were largest near the edges, suggesting that most of the optical signal arose from the outer sheath. To overcome irregular cell orientation found in the brain, we measured polarization changes from a nerve tied in a knot. Our results show that neural activation produces polarization changes that can be imaged even without regular cell orientations. Neural activation expends energy resources and elicits metabolic delivery through blood vessel dilation, increasing blood flow and volume. We used spectroscopic imaging techniques combined with electrophysiological measurements to record evoked neural and hemodynamic responses from the auditory cortex of the rat. By using implantable optics, we measured responses across natural wake and sleep states, as well as responses following different amounts of sleep deprivation. During quiet sleep, evoked metabolic responses were larger compared to wake, perhaps because blood vessels were more compliant. When animals were sleep deprived, evoked hemodynamic responses were smaller following longer periods of deprivation. These results suggest that prolonged neural activity through sleep deprivation may diminish vascular compliance as indicated by the blunted vascular response. Subsequent sleep may allow vessels to relax, restoring their ability to deliver blood. These results also suggest that severe sleep deprivation or chronic

  20. Hemodynamic effects of prazosin in chronic heart failure.

    PubMed

    Parmley, W W; Chatterjee, K; Arnold, S; Rubin, S A; Brundage, B H; Williams, R L; Ports, T; Chuck, L; Rouleau, J

    1981-09-01

    Three series of investigations were carried out with prazosin (PZN) hydrochloride. In the first, hemodynamic effects of PZN were compared with those of hydralazine (HDZ) in 11 patients with chronic congestive heart failure (CHF). In doses up to 5 mg, PZN increased cardiac output (CO) 20% accompanied by a 20% decrease in pulmonary capillary wedge pressure (LVFP). HDZ increased CO by 50% with little or no effect on LVFP. An additional 12 patients were given multiple 5 mg doses of PZN at 6-hour intervals with measurements of hemodynamic and plasma blood levels. Results suggested an attenuation of the effects of PZN on increasing CO but not on decreasing LVFP. This attenuation of CO was not due to inadequate plasma levels. Acute exercise studies (supine bicycle) were performed in 10 patients with severe CHF before and after the administration of several doses of PZN. There appeared to be a greater effect of PZN during exercise than at rest, with a beneficial increase in CO and reduction in LVFP. These data suggest that, despite hemodynamic attenuation of its effects on CO at rest, PZN may still be beneficial to active patients with CHF. In vitro studies with various vasodilators were performed to evaluate potential intropic effects. Isometric force (cat papillary muscle) increased 2% with 10-4M and 31% with 10-3M HDZ. PZN increased force 4% at 10-6M and 18% at 10-4M. Captopril did not increase force development at any dose level. The doses of HDZ and PZN that increased force development were higher than usual clinical doses.

  1. Post-Treatment Hemodynamics of a Basilar Aneurysm and Bifurcation

    SciTech Connect

    Ortega, J; Hartman, J; Rodriguez, J; Maitland, D

    2008-01-16

    Aneurysm re-growth and rupture can sometimes unexpectedly occur following treatment procedures that were initially considered to be successful at the time of treatment and post-operative angiography. In some cases, this can be attributed to surgical clip slippage or endovascular coil compaction. However, there are other cases in which the treatment devices function properly. In these instances, the subsequent complications are due to other factors, perhaps one of which is the post-treatment hemodynamic stress. To investigate whether or not a treatment procedure can subject the parent artery to harmful hemodynamic stresses, computational fluid dynamics simulations are performed on a patient-specific basilar aneurysm and bifurcation before and after a virtual endovascular treatment. The simulations demonstrate that the treatment procedure produces a substantial increase in the wall shear stress. Analysis of the post-treatment flow field indicates that the increase in wall shear stress is due to the impingement of the basilar artery flow upon the aneurysm filling material and to the close proximity of a vortex tube to the artery wall. Calculation of the time-averaged wall shear stress shows that there is a region of the artery exposed to a level of wall shear stress that can cause severe damage to endothelial cells. The results of this study demonstrate that it is possible for a treatment procedure, which successfully excludes the aneurysm from the vascular system and leaves no aneurysm neck remnant, to elevate the hemodynamic stresses to levels that are injurious to the immediately adjacent vessel wall.

  2. Effect of dialysate temperature on hemodynamic stability among hemodialysis patients.

    PubMed

    Azar, Ahmad Taher

    2009-07-01

    Cooling the dialysate below 36.5 degrees C is an important factor that contributes to hemodynamic stability in patients during hemodialysis (HD). In this study, the effect of dialysate temperature on hemodynamic stability, patients' perception of dialysis discomfort and post dialysis fatigue were assessed in a group of patients on HD. A total of 50 patients, all of whom were on 3-times-per-week dialysis regimen, were studied. Patients were assessed during six dialysis sessions; in three sessions, the dialysate temperature was normal (37 degrees C) and in three other sessions, the dialysate temperature was low (35 degrees C). Specific scale questionnaires were used in each dialysis session, to evaluate the symptoms during the dialysis procedure as well as post-dialysis fatigue, and respective scores were noted. The results showed that usage of low dialysate temperature was associated with the following: higher post dialysis systolic blood pressure (P< 0.05) and lower post dialysis heart rate (P< 0.01), with similar ultrafiltration rates, better intra-dialysis symptoms score and post-dialysis fatigue scores (P< 0.001, and P < 0.001, respectively), shorter post-dialysis fatigue period (P< 0.001) as well as higher urea removal (P< 00001) and Kt/V (P< 0.0001). Patients' perceptions were measured by a questionnaire, which showed that 76% of them felt more energetic after dialysis with cool dialysate and requested to be always dialyzed with cool dialysate. Low temperature dialysate is particularly beneficial for highly symptomatic patients, improves tolerance to dialysis in hypotensive patients and helps increase ultrafiltration while maintaining hemodynamic stability during and after dialysis.

  3. Central and regional hemodynamics in prolonged space flights

    NASA Astrophysics Data System (ADS)

    Gazenko, O. G.; Shulzhenko, E. B.; Turchaninova, V. F.; Egorov, A. D.

    This paper presents the results of measuring central and regional (head, forearm, calf) hemodynamics at rest and during provocative tests by the method of tetrapolar rheography in the course of Salyut-6-Soyuz and Salyut-7-Soyuz missions. The measurements were carried out during short-term (19 man-flights of 7 days in duration) and long-term (21 man-flights of 65-237 days in duration) manned missions. At rest, stroke volume (SV) and cardiac output (CO) as well as heart rate (HR) decreased insignificantly (in short-term flights) or remained essentially unchanged (in long-term flights). In prolonged flights CO increased significantly in response to exercise tests due to an increase in HR and the lack of changes in SV. After exercise tests SV and CO decreased as compared to the preflight level. During lower body negative pressure (LBNP) tests HR and CO were slightly higher than preflight. Changes in regional hemodynamics included a distinct decrease of pulse blood filling (PBF) of the calf, a reduction of the tone of large vessels of the calf and small vessels of the forearm. Head examination (in the region of the internal carotid artery) showed a decrease of PBF of the left hemisphere (during flight months 2-8) and a distinct decline of the tone of small vessels, mainly, in the right hemisphere. During LBNP tests the tone of pre- and postcapillary vessels of the brain returned to normal while PBF of the right and left hemisphere vessels declined. It has been shown that regional circulation variations depend on the area examined and are induced by a rearrangement of total hemodynamics of the human body in microgravity. This paper reviews the data concerning changes in central and regional circulation of men in space flights of different duration.

  4. Phonocardiographic Assessment of Hemodynamic Response to Balloon Aortic Valvuloplasty

    PubMed Central

    Bush, Howard S.; Ferguson, James J.

    1990-01-01

    The time to systolic murmur peak is a clinical index that is useful in assessing the severity of valvular aortic stenosis. To determine whether phonocardiography could be used to detect a change in the timing of the murmur and thus to measure hemodynamic improvements in elderly balloon aortic valvuloplasty patients, we retrospectively reviewed phonocardiographic tracings of 18 patients taken before and after the procedure. Ten men and 8 women were included in the study; the mean age was 80.7 ± 11.2 years (range, 64 to 90). Phonocardiographic signals were digitized, and the R-wave to murmur peak interval (R-MP) was measured. In 11 patients, the R-MP decreased (mean decrease, 16% ± 11%): of these, 10 had a significant (> 25%) decrease in mean gradient; 10 had a significant (> 25%) decrease in peak-to-peak gradient; and the average increase in aortic valve area was 38%. Seven patients had an increase in R-MP (mean increase, 10% ± 9%): of these, 6 had a decrease in mean gradient of less than 25%; 6 had a decrease in peak-to-peak gradient of less than 25%; and the average increase in aortic valve area was 21%. Pre- and post-balloon aortic valvuloplasty heart rates were not significantly different (71 ± 8 beats/min versus 73 ± 5 beats/min). In this study, hemodynamic improvements after valvuloplasty were manifested by a reduction in the R-MP interval. We conclude that phonocardiography may be a practical, noninvasive method of assessing the hemodynamic response to balloon aortic valvuloplasty. (Texas Heart Institute Journal 1990;17:42-7) PMID:15227188

  5. A Simple Echocardiographic Prediction Rule for Hemodynamics in Pulmonary Hypertension

    PubMed Central

    Opotowsky, Alexander R.; Ojeda, Jason; Rogers, Frances; Prasanna, Vikram; Clair, Mathieu; Moko, Lilamarie; Vaidya, Anjali; Afilalo, Jonathan; Forfia, Paul R.

    2012-01-01

    Background Pulmonary hypertension (PH) has diverse causes with heterogeneous physiology compelling distinct management. Differentiating patients with primarily elevated pulmonary vascular resistance (PVR) from those with PH predominantly due to elevated left sided filling pressure is critical. Methods and Results We reviewed hemodynamics, echocardiography, and clinical data for 108 patients seen at a referral PH clinic with transthoracic echocardiogram and right heart catheterization within 1 year. We derived a simple echocardiographic prediction rule to allow hemodynamic differentiation of PH due to pulmonary vascular disease (PHPVD, defined as pulmonary artery wedge pressure (PAWP) ≤ 15mmHg and PVR >3WU). Age averaged 61.3±14.8 years, μPAWP and PVR were 16.4±7.1mmHg and 6.3±4.0WU respectively, and 52 (48.1%) patients fulfilled PHPVD hemodynamic criteria. The derived prediction rule ranged from −2 to +2 with higher scores suggesting higher probability of PHPVD: +1 point for left atrial AP dimension<3.2cm; +1 for presence of a mid-systolic notch or acceleration time<80msec; −1 for lateral mitral E:e′>10; −1 for left atrial AP dimension>4.2cm. PVR increased stepwise with score (for −2, 0 and +2, μPVR were 2.5, 4.5, and 8.1WU) while the inverse was true for PAWP (corresponding μPAWP were 21.5, 16.5 and 10.4mmHg). Among subjects with complete data, the score had an AUC of 0.921 for PHPVD. A score ≥ 0 had 100% sensitivity and 69.3% positive predictive value for PHPVD, with 62.3% specificity. No patients with a negative score had PHPVD. Patients with a negative score and acceleration time >100msec had normal PVR (μPVR=1.8WU, range=0.7–3.2WU). Conclusions We present a simple echocardiographic prediction rule that accurately defines PH hemodynamics facilitates improved screening and focused clinical investigation for PH diagnosis and management. PMID:22914595

  6. Enteral nutrition in the hemodynamically unstable critically ill patient.

    PubMed

    Flordelís Lasierra, J L; Pérez-Vela, J L; Montejo González, J C

    2015-01-01

    The benefit of enteral nutrition in critically ill patients has been demonstrated by several studies, especially when it is started early, in the first 24-48h of stay in the Intensive Care Unit, and this practice is currently advised by the main clinical guidelines. The start of enteral nutrition is controversial in patients with hemodynamic failure, since it may trigger intestinal ischemia. However, there are data from experimental studies in animals, as well as from observational studies in humans that allow for hypotheses regarding its beneficial effect and safety. Interventional clinical trials are needed to confirm these findings.

  7. Clinical monitoring of systemic hemodynamics in critically ill newborns.

    PubMed

    de Boode, Willem-Pieter

    2010-03-01

    Circulatory failure is a major cause of mortality and morbidity in critically ill newborn infants. Since objective measurement of systemic blood flow remains very challenging, neonatal hemodynamics is usually assessed by the interpretation of various clinical and biochemical parameters. An overview is given about the predictive value of the most used indicators of circulatory failure, which are blood pressure, heart rate, urine output, capillary refill time, serum lactate concentration, central-peripheral temperature difference, pH, standard base excess, central venous oxygen saturation and colour.

  8. Hemodynamics and annuloplasty in isolated mitral regurgitation in children.

    PubMed

    Sulayman, R; Mathew, R; Thilenius, O G; Replogle, R; Arcilla, R A

    1975-12-01

    Isolated mitral insufficiency in children is quantitated angiographically by comparing the stroke volumes of the right ventricle and left ventricle. The disease results in greater enlargement of the left atrium than of the left ventricle and is accompanied by a significant increase in left atrial "distensibility." Right and left heart pressures may be normal or may be increased; they tend to be elevated in the group with regurgitant fractions of over 50%. Annuloplasty results in marked clinical and hemodynamic improvement and may even be corrective.

  9. Modeling Fluid Flows in Distensible Tubes for Applications in Hemodynamics

    NASA Astrophysics Data System (ADS)

    Descovich, X.; Pontrelli, G.; Melchionna, S.; Succi, S.; Wassertheurer, S.

    2013-05-01

    We present a lattice Boltzmann (LB) model for the simulation of hemodynamic flows in the presence of compliant walls. The new scheme is based on the use of a continuous bounce-back boundary condition, as combined with a dynamic constitutive relation between the flow pressure at the wall and the resulting wall deformation. The method is demonstrated for the case of two-dimensional (axisymmetric) pulsatile flows, showing clear evidence of elastic wave propagation of the wall perturbation in response to the fluid pressure. The extension of the present two-dimensional axisymmetric formulation to more general three-dimensional geometries is currently under investigation.

  10. From hemodynamic towards cardiomechanic sensors in implantable devices

    NASA Astrophysics Data System (ADS)

    Ferek-Petric, Bozidar

    2013-06-01

    Sensor could significantly improve the cardiac electrotherapy. It has to provide long-term stabile signal not impeding the device longevity and lead reliability. It may not introduce special implantation and adjustment procedures. Hemodynamic sensors based on the blood flow velocity and cardiomechanic sensors based on the lead bending measurement are disclosed. These sensors have a broad clinical utility. Triboelectric and high-frequency lead bending sensors yield accurate and stable signals whereby functioning with every cardiac lead. Moreover, high frequency measurement avoids use of any kind of special hardware mounted on the cardiac lead.

  11. Effect of continuous ATP injection on human hemodynamics.

    PubMed

    Komukai, Kimiaki; Hashimoto, Koichi; Shibata, Takahiro; Iwano, Keiji; Muto, Makoto; Mogi, Junichi; Imai, Kamon; Horie, Toshinobu; Mochizuki, Seibu

    2002-10-01

    Continuous ATP injection is used clinically for Tl imaging or coronary flow measurement and because the effect on human hemodynamics is unknown, the present study investigated it in 14 patients undergoing heart catheter examination. Continuous ATP injection induced chest symptoms in 13 of the patients and second-degree atrioventricular block in one, but these complications disappeared immediately after the end of ATP infusion. Continuous ATP injection decreased aortic pressure, but increased pulmonary artery pressure, right atrial pressure and pulmonary capillary wedge pressure. ATP increased heart rate, stroke volume and cardiac output, the latter the result of an increase in preload, a decrease in afterload, and the increase in heart rate. PMID:12381087

  12. Effects of Dietary Nitrates on Systemic and Cerebrovascular Hemodynamics

    PubMed Central

    Curry, Bryan H.; Adams, Richard G.; Asadi, M. Sadegh; Millis, Richard M.; Haddad, Georges E.

    2013-01-01

    Cerebral blood flow dysregulation is often associated with hypertension. We hypothesized that a beetroot juice (BRJ) treatment could decrease blood pressure and cerebrovascular resistance (CVR). We subjected 12 healthy females to control and BRJ treatments. Cerebrovascular resistance index (CVRI), systolic blood pressure (SBP), total vascular resistance (TVR), and the heart rate-systolic pressure product (RPP) measured at rest and at two exercise workloads were lower after the BRJ treatment. CVRI, SBP, and RPP were lower without a lower TVR at the highest exercise level. These findings suggest improved systemic and cerebral hemodynamics that could translate into a dietary treatment for hypertension. PMID:24455404

  13. Bedside calculation of hemodynamic parameters with a hand held programmable calculator. Part II: Programs for hemodynamic and oxygen transport parameters computation.

    PubMed

    Laurent, M

    1980-01-01

    Two programs calculating oxygen transport parameters and hemodynamic values respectively are described. They may be used indifferently with HP 67 or HP 97 Hewlett Packard calculators. (Acta anaesth. belg., 1980, 31, 53-59).

  14. Effect of Maturation on Hemodynamic and Autonomic Control Recovery Following Maximal Running Exercise in Highly Trained Young Soccer Players

    PubMed Central

    Buchheit, Martin; Al Haddad, Hani; Mendez-Villanueva, Alberto; Quod, Marc J.; Bourdon, Pitre C.

    2011-01-01

    The purpose of this study was to examine the effect of maturation on post-exercise hemodynamic and autonomic responses. Fifty-five highly trained young male soccer players (12–18 years) classified as pre-, circum-, or post-peak height velocity (PHV) performed a graded running test to exhaustion on a treadmill. Before (Pre) and after (5th–10th min, Post) exercise, heart rate (HR), stroke volume (SV), cardiac output (CO), arterial pressure (AP), and total peripheral resistance (TPR) were monitored. Parasympathetic (high frequency [HFRR] of HR variability (HRV) and baroreflex sensitivity [Ln BRS]) and sympathetic activity (low frequency [LFSAP] of systolic AP variability) were estimated. Post-exercise blood lactate [La]b, the HR recovery (HRR) time constant, and parasympathetic reactivation (time-varying HRV analysis) were assessed. In all three groups, exercise resulted in increased HR, CO, AP, and LFSAP (P < 0.001), decreased SV, HFRR, and Ln BRS (all P < 0.001), and no change in TPR (P = 0.98). There was no “maturation × time” interaction for any of the hemodynamic or autonomic variables (all P > 0.22). After exercise, pre-PHV players displayed lower SV, CO, and [La]b, faster HRR and greater parasympathetic reactivation compared with circum- and post-PHV players. Multiple regression analysis showed that lean muscle mass, [La]b, and Pre parasympathetic activity were the strongest predictors of HRR (r2 = 0.62, P < 0.001). While pre-PHV players displayed a faster HRR and greater post-exercise parasympathetic reactivation, maturation had little influence on the hemodynamic and autonomic responses following maximal running exercise. HRR relates to lean muscle mass, blood acidosis, and intrinsic parasympathetic function, with less evident impact of post-exercise autonomic function. PMID:22013423

  15. Hemodynamic Measurement Using Four-Dimensional Phase-Contrast MRI: Quantification of Hemodynamic Parameters and Clinical Applications

    PubMed Central

    Ha, Hojin; Kim, Guk Bae; Kweon, Jihoon; Lee, Sang Joon; Kim, Young-Hak; Lee, Deok Hee

    2016-01-01

    Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions. PMID:27390537

  16. Hemodynamic Measurement Using Four-Dimensional Phase-Contrast MRI: Quantification of Hemodynamic Parameters and Clinical Applications.

    PubMed

    Ha, Hojin; Kim, Guk Bae; Kweon, Jihoon; Lee, Sang Joon; Kim, Young-Hak; Lee, Deok Hee; Yang, Dong Hyun; Kim, Namkug

    2016-01-01

    Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions. PMID:27390537

  17. Encephalic hemodynamic phases in subarachnoid hemorrhage: how to improve the protective effect in patient prognoses

    PubMed Central

    de Lima Oliveira, Marcelo; de Azevedo, Daniel Silva; de Azevedo, Milena Krajnyk; de Carvalho Nogueira, Ricardo; Teixeira, Manoel Jacobsen; Bor-Seng-Shu, Edson

    2015-01-01

    Subarachnoid hemorrhage is frequently associated with poor prognoses. Three different hemodynamic phases were identified during subarachnoid hemorrhage: oligemia, hyperemia, and vasospasm. Each phase is associated with brain metabolic changes. In this review, we correlated the hemodynamic phases with brain metabolism and potential treatment options in the hopes of improving patient prognoses. PMID:26109948

  18. Endovascular Treatment of Thoracic Aortic Dissection: Hemodynamic Shear Stress Study

    NASA Astrophysics Data System (ADS)

    Tang, Yik Sau; Lai, Siu Kai; Cheng, Stephen Wing Keung; Chow, Kwok Wing

    2012-11-01

    Thoracic Aortic Dissection (TAD), a life threatening cardiovascular disease, occurs when blood intrudes into the layers of the aortic wall, creating a new artificial channel (the false lumen) beside the original true lumen. The weakened false lumen wall may expand, enhancing the risk of rupture and resulting in high mortality. Endovascular treatment involves the deployment of a stent graft into the aorta, thus blocking blood from entering the false lumen. Due to the irregular geometry of the aorta, the stent graft, however, may fail to conform to the vessel curvature, and would create a ``bird-beak'' configuration, a wedge-shaped domain between the graft and the vessel wall. Computational fluid dynamics analysis is employed to study the hemodynamics of this pathological condition. With the `beaking' configuration, the local hemodynamic shear stress will drop below the threshold of safety reported earlier in the literature. The oscillating behavior of the shear stress might lead to local inflammation, atherosclerosis and other undesirable consequences. Supported by the Innovation and Technology Fund of the Hong Kong Government.

  19. Hemodynamic transition driven by stent porosity in sidewall aneurysms.

    PubMed

    Bouillot, Pierre; Brina, Olivier; Ouared, Rafik; Lovblad, Karl-Olof; Farhat, Mohamed; Pereira, Vitor Mendes

    2015-05-01

    The healing process of intracranial aneurysms (IAs) treated with flow diverter stents (FDSs) depends on the IA flow modifications and on the epithelization process over the neck. In sidewall IA models with straight parent artery, two main hemodynamic regimes with different flow patterns and IA flow magnitude were broadly observed for unstented and high porosity stented IA on one side, and low porosity stented IA on the other side. The hemodynamic transition between these two regimes is potentially involved in thrombosis formation. In the present study, CFD simulations and multi-time lag (MTL) particle imaging velocimetry (PIV) measurements were combined to investigate the physical nature of this transition. Measurable velocity fields and non-measurable shear stress and pressure fields were assessed experimentally and numerically in the aneurysm volume in the presence of stents with various porosities. The two main regimes observed in both PIV and CFD showed typical flow features of shear and pressure driven regimes. In particular, the waveform of the averaged IA velocities was matching both the shear stress waveform at IA neck or the pressure gradient waveform in parent artery. Moreover, the transition between the two regimes was controlled by stent porosity: a decrease of stent porosity leads to an increase (decrease) of pressure differential (shear stress) through IA neck. Finally, a good PIV-CFD agreement was found except in transitional regimes and low motion eddies due to small mismatch of PIV-CFD running conditions. PMID:25798761

  20. Bayesian hemodynamic parameter estimation by bolus tracking perfusion weighted imaging.

    PubMed

    Boutelier, Timothé; Kudo, Koshuke; Pautot, Fabrice; Sasaki, Makoto

    2012-07-01

    A delay-insensitive probabilistic method for estimating hemodynamic parameters, delays, theoretical residue functions, and concentration time curves by computed tomography (CT) and magnetic resonance (MR) perfusion weighted imaging is presented. Only a mild stationarity hypothesis is made beyond the standard perfusion model. New microvascular parameters with simple hemodynamic interpretation are naturally introduced. Simulations on standard digital phantoms show that the method outperforms the oscillating singular value decomposition (oSVD) method in terms of goodness-of-fit, linearity, statistical and systematic errors on all parameters, especially at low signal-to-noise ratios (SNRs). Delay is always estimated sharply with user-supplied resolution and is purely arterial, by contrast to oSVD time-to-maximum TMAX that is very noisy and biased by mean transit time (MTT), blood volume, and SNR. Residue functions and signals estimates do not suffer overfitting anymore. One CT acute stroke case confirms simulation results and highlights the ability of the method to reliably estimate MTT when SNR is low. Delays look promising for delineating the arterial occlusion territory and collateral circulation. PMID:22410325

  1. Neuronal or Hemodynamic? Grappling with the Functional MRI Signal

    PubMed Central

    2014-01-01

    Abstract Magnetic resonance imaging (MRI) and functional MRI (fMRI) continue to advance because creative physicists, engineers, neuroscientists, clinicians, and physiologists find new ways for extracting more information from the signal. Innovations in pulse sequence design, paradigm design, and processing methods have advanced the field and firmly established fMRI as a cornerstone for understanding the human brain. In this article, the field of fMRI is described through consideration of the central problem of separating hemodynamic from neuronal information. Discussed here are examples of how pulse sequences, activation paradigms, and processing methods are integrated such that novel, high-quality information can be obtained. Examples include the extraction of information such as activation onset latency, metabolic rate, neuronal adaptation, vascular patency, vessel diameter, vigilance, and subvoxel activation. Experimental measures include time series latency, hemodynamic shape, MR phase, multivoxel patterns, ratios of activation-related R2* to R2, metabolic rate changes, fluctuation correlations and frequencies, changes in fluctuation correlations and frequencies over time, resting correlation states, echo time dependence, and more. PMID:25093397

  2. Antiadrenergic and hemodynamic effects of ranolazine in conscious dogs.

    PubMed

    Zhao, Gong; Walsh, Erin; Shryock, John C; Messina, Eric; Wu, Yuzhi; Zeng, Dewan; Xu, Xiaobin; Ochoa, Manuel; Baker, Stephen P; Hintze, Thomas H; Belardinelli, Luiz

    2011-06-01

    Effects of ranolazine alone and in the presence of phenylephrine (PE) or isoproterenol (ISO) on hemodynamics, coronary blood flow and heart rate (HR) in the absence and presence of hexamethonium (a ganglionic blocker) were studied in conscious dogs. Ranolazine (0.4, 1.2, 3.6, and 6 mg/kg, intravenous) alone caused transient (<1 minute) and reversible hemodynamic changes. PE (0.3-10 μg/kg) caused a dose-dependent increase in blood pressure and decrease in HR. ISO (0.01-0.3 μg/kg) caused a dose-dependent decrease in blood pressure and an increase in HR. Ranolazine at high (11-13 mM), but not at moderate (4-5 mM) concentrations partially attenuated changes in mean arterial blood pressure and HR caused by either PE or ISO in normal conscious dogs. However, in dogs treated with hexamethonium (20 mg/kg) to cause autonomic blockade, ranolazine (both 4-5 and 11-13 μM) significantly attenuated both the PE- and ISO-induced changes in mean arterial blood pressure. The results suggest that a potential antiadrenergic effect of ranolazine was masked by autonomic control mechanisms in conscious dogs but could be observed when these mechanisms were inhibited (eg, in the hexamethonium-treated dog). Ranolazine, at plasma concentrations <10 μM and in conscious dogs with intact autonomic regulation, had minimal antiadrenergic (α and β) effects.

  3. Bioimpedance Measurement of Segmental Fluid Volumes and Hemodynamics

    NASA Technical Reports Server (NTRS)

    Montgomery, Leslie D.; Wu, Yi-Chang; Ku, Yu-Tsuan E.; Gerth, Wayne A.; DeVincenzi, D. (Technical Monitor)

    2000-01-01

    Bioimpedance has become a useful tool to measure changes in body fluid compartment volumes. An Electrical Impedance Spectroscopic (EIS) system is described that extends the capabilities of conventional fixed frequency impedance plethysmographic (IPG) methods to allow examination of the redistribution of fluids between the intracellular and extracellular compartments of body segments. The combination of EIS and IPG techniques was evaluated in the human calf, thigh, and torso segments of eight healthy men during 90 minutes of six degree head-down tilt (HDT). After 90 minutes HDT the calf and thigh segments significantly (P < 0.05) lost conductive volume (eight and four percent, respectively) while the torso significantly (P < 0.05) gained volume (approximately three percent). Hemodynamic responses calculated from pulsatile IPG data also showed a segmental pattern consistent with vascular fluid loss from the lower extremities and vascular engorgement in the torso. Lumped-parameter equivalent circuit analyses of EIS data for the calf and thigh indicated that the overall volume decreases in these segments arose from reduced extracellular volume that was not completely balanced by increased intracellular volume. The combined use of IPG and EIS techniques enables noninvasive tracking of multi-segment volumetric and hemodynamic responses to environmental and physiological stresses.

  4. Bicuspid aortic valve hemodynamics: a fluid-structure interaction study

    NASA Astrophysics Data System (ADS)

    Chandra, Santanu; Seaman, Clara; Sucosky, Philippe

    2011-11-01

    The bicuspid aortic valve (BAV) is a congenital defect in which the aortic valve forms with two leaflets instead of three. While calcific aortic valve disease (CAVD) also develops in the normal tricuspid aortic valve (TAV), its progression in the BAV is more rapid. Although studies have suggested a mechano-potential root for the disease, the native BAV hemodynamics remains largely unknown. This study aimed at characterizing BAV hemodynamics and quantifying the degree of wall-shear stress (WSS) abnormality on BAV leaflets. Fluid-structure interaction models validated with particle-image velocimetry were designed to predict the flow and leaflet dynamics in idealized TAV and BAV anatomies. Valvular function was quantified in terms of the effective orifice area. The regional leaflet WSS was characterized in terms of oscillatory shear index, temporal shear magnitude and temporal shear gradient. The predictions indicate the intrinsic degree of stenosis of the BAV anatomy, reveal drastic differences in shear stress magnitude and pulsatility on BAV and TAV leaflets and confirm the side- and site-specificity of the leaflet WSS. Given the ability of abnormal fluid shear stress to trigger valvular inflammation, these results support the existence of a mechano-etiology of CAVD in the BAV.

  5. Hemodynamic simulations in coronary aneurysms of children with Kawasaki disease

    NASA Astrophysics Data System (ADS)

    Sengupta, Dibyendu; Burns, Jane; Marsden, Alison

    2009-11-01

    Kawasaki disease (KD) is a serious pediatric illness affecting the cardiovascular system. One of the most serious complications of KD, occurring in about 25% of untreated cases, is the formation of large aneurysms in the coronary arteries, which put patients at risk for myocardial infarction. In this project we performed patient specific computational simulations of blood flow in aneurysmal left and right coronary arteries of a KD patient to gain an understanding about their hemodynamics. Models were constructed from CT data using custom software. Typical pulsatile flow waveforms were applied at the model inlets, while resistance and RCR lumped models were applied and compared at the outlets. Simulated pressure waveforms compared well with typical physiologic data. High wall shear stress values are found in the narrow region at the base of the aneurysm and low shear values occur in regions of recirculation. A Lagrangian approach has been adopted to perform particle tracking and compute particle residence time in the recirculation. Our long-term goal will be to develop links between hemodynamics and the risk for thrombus formation in order to assist in clinical decision-making.

  6. Hemodynamic effects of isoproterenol in canine endotoxin shock

    PubMed Central

    Starzecki, Boleslaw; Spink, Wesley W.

    1968-01-01

    Myocardial function and peripheral hemodynamic alterations were measured through the late stages of canine endotoxin shock. 60 min postendotoxin paired animals were given infusions of either 5 ml/kg per hr of 5% dextrose or dextrose plus isoproterenol (0.25 μg/kg per min). Comparable blood lactic and pyruvic acid levels were determined, the excess lactic acid calculated, and pH values were obtained. During the initial stages the classic pattern of hemodynamic alterations was observed; an excess of lactic acid appeared and the pH decreased. Outstanding was evidence of markedly reduced myocardial function in the late stages of shock with progressive rise in left ventricular end diastolic pressure (LVEDP), low cardiac index, rise of central venous pressure, increased central blood volume, tachycardia, and declining arterial pressure. Analyses of left ventricular function curves also indicated myocardial failure. Infusion of dextrose alone failed to decrease mortality rate (10 of 18 dying), whereas the rate was significantly decreased with isoproterenol (2 of 18). Dextrose infusion did not benefit myocardial function. Isoproterenol resulted in a marked improvement in myocardial action with a significant increase in heart work associated with, yet very minor, increments of LVEDP. In addition, tachycardia subsided, peripheral resistance decreased, and the blood pressure stabilized. The prognostic value of excess lactic acid was doubtful but a progressive fall in later stages was associated with survival. Images PMID:5676517

  7. Hemodynamic responses to amygdaloid stimulation in spontaneously hypertensive rats.

    PubMed

    Galeno, T M; Brody, M J

    1983-08-01

    Our studies were done to determine 1) the regional hemodynamic effects of stimulating the central amygdaloid nucleus in conscious and anesthetized rats and 2) whether these effects differ between normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Flow was recorded with miniaturized pulsed Doppler probes placed on the renal and superior mesenteric arteries and the lower abdominal aorta. In rats anesthetized with Dialurethane, electrical stimulation elicited a depressor response accompanied by a decrease in hindquarter vascular resistance, with little or no change in heart rate or renal or mesenteric resistance in both SHR and WKY. By contrast, in conscious rats, stimulation was accompanied by a pressor response, tachycardia, and renal and mesenteric vasoconstriction in both groups. Hindquarter vascular resistance was unchanged in WKY and decreased at higher frequencies in SHR. There were no significant differences between SHR and WKY, whether anesthetized or awake, in hemodynamic responses to amygdaloid stimulation. Despite previous evidence indicating that the central amygdaloid nucleus contributes to the development of spontaneous hypertension, our results show that stimulation of this region does not elicit exaggerated cardiovascular responses in SHR.

  8. Closed-Loop Dynamic Modeling of Cerebral Hemodynamics

    PubMed Central

    Marmarelis, V. Z.; Shin, D. C.; Orme, M. E.; Zhang, R.

    2013-01-01

    The dynamics of cerebral hemodynamics have been studied extensively because of their fundamental physiological and clinical importance. In particular, the dynamic processes of cerebral flow autoregulation and CO2 vasomotor reactivity have attracted broad attention because of their involvement in a host of pathologies and clinical conditions (e.g. hypertension, syncope, stroke, traumatic brain injury, vascular dementia, Alzheimer’s disease, mild cognitive impairment etc.). This raises the prospect of useful diagnostic methods being developed on the basis of quantitative models of cerebral hemodynamics, if cerebral vascular dysfunction can be quantified reliably from data collected within practical clinical constraints. This paper presents a modeling method that utilizes beat-to-beat measurements of mean arterial blood pressure, cerebral blood flow velocity and end-tidal CO2 (collected non-invasively under resting conditions) to quantify the dynamics of cerebral flow autoregulation (CFA) and cerebral vasomotor reactivity (CVMR). The unique and novel aspect of this dynamic model is that it is nonlinear and operates in a closed-loop configuration. PMID:23292615

  9. Immediate hemodynamic response to furosemide in patients undergoing chronic hemodialysis.

    PubMed

    Schmieder, R E; Messerli, F H; deCarvalho, J G; Husserl, F E

    1987-01-01

    To evaluate the effect of furosemide on cardiovascular hemodynamics in patients with end-stage renal failure, we studied ten patients undergoing hemodialysis three times a week. Arterial pressure, heart rate, and cardiac output (indocyanine green dye) were measured in triplicate; total peripheral resistance and central blood volume were calculated by standard formulas. Hemodynamics were determined at baseline and 5, 10, 15, and 30 minutes after intravenous (IV) bolus injection of furosemide 60 mg. Furosemide produced a decrease in central blood volume of -13% +/- 2.2% from pretreatment values (P less than .01) that was most pronounced five minutes after injection, together with a fall in cardiac output (from 6.76 +/- 0.59 to 6.17 +/- 0.52 L/min, P less than .10). Stroke volume decreased with a maximum fall occurring after 15 minutes (from 84 +/- 7 to 79 +/- 7 mL/min, P less than .05), and total peripheral resistance increased (from 15.8 +/- 2.1 to 17.8 +/- 2.3 units, P less than .05) after furosemide. Arterial pressure and heart rate did not change. The decrease in central blood volume reflects a shift of the total blood volume from the cardiopulmonary circulation to the periphery, suggesting dilation of the peripheral venous bed. Thus, even in patients undergoing hemodialysis, furosemide acutely decreases left ventricular preload by venous dilation and should therefore prove to be beneficial in acute volume overload.

  10. Computational Hemodynamic Simulation of Human Circulatory System under Altered Gravity

    NASA Technical Reports Server (NTRS)

    Kim. Chang Sung; Kiris, Cetin; Kwak, Dochan

    2003-01-01

    A computational hemodynamics approach is presented to simulate the blood flow through the human circulatory system under altered gravity conditions. Numerical techniques relevant to hemodynamics issues are introduced to non-Newtonian modeling for flow characteristics governed by red blood cells, distensible wall motion due to the heart pulse, and capillary bed modeling for outflow boundary conditions. Gravitational body force terms are added to the Navier-Stokes equations to study the effects of gravity on internal flows. Six-type gravity benchmark problems are originally presented to provide the fundamental understanding of gravitational effects on the human circulatory system. For code validation, computed results are compared with steady and unsteady experimental data for non-Newtonian flows in a carotid bifurcation model and a curved circular tube, respectively. This computational approach is then applied to the blood circulation in the human brain as a target problem. A three-dimensional, idealized Circle of Willis configuration is developed with minor arteries truncated based on anatomical data. Demonstrated is not only the mechanism of the collateral circulation but also the effects of gravity on the distensible wall motion and resultant flow patterns.

  11. [Influence of pilot's professional activity on the adaptive character of hemodynamic reactions to the tilt test].

    PubMed

    Batishcheva, G A; Chernov, Iu N; Soldatov, S K; Goncharova, N Iu; Khomenko, M N

    2010-01-01

    The comparative study of blood circulation reaction to the tilt test was performed with three groups of essentially healthy subjects: AF pilots (n = 72), locomen (n = 44) and students of Military Institute of Radio Electronics (n = 32). In each group, adequate adaptive reactions were due to the eukinetic hemodynamics with steady minute volume and blood pressure values combined with heart rate increase by 10-12%. Hypokinetic hemodynamics caused 20% growth in minute volume during the initial 5 minutes of tilting in pilots versus 8-12% growth in non-flyers. Hyperkinetic hemodynamics was responsible for the minute volume growth in pilots but not in the other groups of subjects. Parasympathetic system activation was peculiar of hypokinetic hemodynamics, while sympathetic system activation was associated with hyperkinetic hemodynamics. These results point to a larger body functional reserve in pilots compared with the other subjects as a by-effect of the profession.

  12. [Use of alpha-tocopherol acetate in the treatment of hemodynamic disorders in patients with pulmonary tuberculosis].

    PubMed

    Ditiatkov, A E; Tikhonov, V A; Radzevich, A E; Zholnin, P A

    2005-01-01

    Examination of 101 patients with pulmonary tuberculosis established the impact of specific intoxication on central hemodynamics in 51 patients. Specific treatment was found to have a certain positive effect on impaired hemodynamics. However, there were no significant changes in patients with severe tuberculosis. Hemodynamics substantially improved when alpha-tocopherol acetate was supplemented to antibacterial therapy.

  13. Estimating Hemodynamic Responses to the Wingate Test Using Thoracic Impedance

    PubMed Central

    Astorino, Todd A.; Bovee, Curtis; DeBoe, Ashley

    2015-01-01

    Techniques including direct Fick and Doppler echocardiography are frequently used to assess hemodynamic responses to exercise. Thoracic impedance has been shown to be a noninvasive alternative to these methods for assessing these responses during graded exercise to exhaustion, yet its feasibility during supramaximal bouts of exercise is relatively unknown. We used thoracic impedance to estimate stroke volume (SV) and cardiac output (CO) during the Wingate test (WAnT) and compared these values to those from graded exercise testing (GXT). Active men (n = 9) and women (n = 7) (mean age = 24.8 ± 5.9 yr) completed two Wingate tests and two graded exercise tests on a cycle ergometer. During exercise, heart rate (HR), SV, and CO were continuously estimated using thoracic impedance. Repeated measures analysis of variance was used to identify potential differences in hemodynamic responses across protocols. Results: Maximal SV (138.6 ± 37.4 mL vs. 135.6 ± 26.9 mL) and CO (24.5 ± 6.1 L·min-1 vs. 23.7 ± 5.1 L·min-1) were similar (p > 0.05) between repeated Wingate tests. Mean maximal HR was higher (p < 0.01) for GXT (185 ± 7 b·min-1) versus WAnT (177 ± 11 b·min-1), and mean SV was higher in response to WAnT (137.1 ± 32.1 mL) versus GXT (123.0 ± 32.0 mL), leading to similar maximal cardiac output between WAnT and GXT (23.9 ± 5.6 L·min-1 vs. 22.5 ± 6.0 L·min-1). Our data show no difference in hemodynamic responses in response to repeated administrations of the Wingate test. In addition, the Wingate test elicits similar cardiac output compared to progressive cycling to VO2max. Key points Measurement of cardiac output (CO), the rate of oxygen transport delivered by the heart to skeletal muscle, is not widely-employed in Exercise Physiology due to the level of difficulty and invasiveness characteristic of most techniques used to measure this variable. Nevertheless, thoracic impedance has been shown to provide a noninvasive and simpler approach to continuously

  14. Growth and hemodynamics after early embryonic aortic arch occlusion*

    PubMed Central

    Lindsey, Stephanie E.; Menon, Prahlad G.; Kowalski, William J.; Shekhar, Akshay; Yalcin, Huseyin C.; Nishimura, Nozomi; Schaffer, Chris B.; Butcher, Jonathan T.; Pekkan, Kerem

    2015-01-01

    The majority of severe clinically significant forms of congenital heart disease (CHD) is associated with great artery lesions, including hypoplastic, double, right or interrupted aortic arch morphologies. While fetal and neonatal interventions are advancing, their potential ability to restore cardiac function, optimal timing, location, and intensity required for intervention remain largely unknown. We here combine computational fluid dynamics (CFD) simulations with in vivo experiments to test how individual pharyngeal arch artery hemodynamics alters as a result of local interventions to obstruct individual arch artery flow. Simulated isolated occlusions within each pharyngeal arch artery were created with image derived three-dimensional (3D) reconstructions of normal chick pharyngeal arch anatomy at Hamburger-Hamilton (HH) developmental stages HH18 and HH24. Acute flow redistributions were then computed using in vivo measured subject-specific aortic sinus inflow velocity profiles. A kinematic vascular growth-rendering algorithm was then developed and implemented to test the role of changing local wall shear stress patterns in downstream 3D morphogenesis of arch arteries. CFD simulations predicted that altered pressure gradients and flow redistributions were most sensitive to occlusion of the IVth arches. To evaluate these simulations experimentally, a novel in vivo experimental model of pharyngeal arch occlusion was developed and implemented using two-photon microscopy guided femtosecond laser based photodisruption surgery. The right IVth arch was occluded at HH18, and resulting diameter changes were followed for up to 24 hours. Pharyngeal arch diameter responses to acute hemodynamic changes were predicted qualitatively but poorly quantitatively. Chronic growth and adaptation to hemodynamic changes however were predicted in a subset of arches. Our findings suggest that this complex biodynamic process is governed through more complex forms of mechanobiological

  15. Systemic arterial hemodynamics in the diamond python Morelia spilotes.

    PubMed

    Avolio, A P; O'Rourke, M F; Bulliman, B T; Webster, M E; Mang, K

    1982-09-01

    Studies of pulsatile systemic arterial hemodynamics were conducted in 10 diamond python snakes to test the hypothesis that body shape--through spatial dispersion of peripheral reflecting sites--is an important determinant of impedance patterns and of pulse wave contour. Findings support the hypothesis. Flow patterns in the aortic roots were similar to those in humans, sheep, dogs, rabbits, and guinea pigs, but in contrast to larger animals, little change in flow contour was seen in other arteries. Pressure wave contour was similar in all systemic arteries from which records were taken with no secondary diastolic wave under any circumstances. Impedance patterns at different sites showed none of the fluctuations that in other animals are attributable to discrete wave reflection. Discrete proximal wave reflection at the confluence of aortic arches was minimal. Data are explicable on the basis of widely distributed peripheral reflecting sites--a consequence of the snake's long and tapered body.

  16. CFD modeling of pulsatile hemodynamics in the total cavopulmonary connection

    NASA Astrophysics Data System (ADS)

    Zobaer, S. M. Tareq; Hasan, A. B. M. Toufique

    2016-07-01

    Total cavopulmonary connection is a blood flow pathway which is created surgically by an operation known as Fontan procedure, performed on children with single ventricle heart defects. Recent studies have shown that the hemodynamics in the connection can be strongly influenced by the presence of pulsatile flow. The aim of this paper is model the pulsatile flow patterns, and to calculate the vorticity field and power losses in an idealized 1.5D offset model of Total Cavopulmonary Connection. A three-dimensional polyhedral mesh was constructed for the numerical simulation. The rheological properties of blood were considered as Newtonian, and flow in the connection was assumed to be laminar. The results demonstrated complex flow patterns in the connection. The outcomes of the simulation showed reasonable agreement with the results available in the literature for a similar model.

  17. [Current concepts on hemodynamic support and therapy in septic shock].

    PubMed

    Rocha, Leonardo Lima; Pessoa, Camila Menezes Souza; Corrêa, Thiago Domingos; Pereira, Adriano José; de Assunção, Murillo Santucci Cesar; Silva, Eliézer

    2015-01-01

    Severe sepsis and septic shock represent a major healthcare challenge. Much of the improvement in mortality associated with septic shock is related to early recognition combined with timely fluid resuscitation and adequate antibiotics administration. The main goals of septic shock resuscitation include intravascular replenishment, maintenance of adequate perfusion pressure and oxygen delivery to tissues. To achieve those goals, fluid responsiveness evaluation and complementary interventions - i.e. vasopressors, inotropes and blood transfusion - may be necessary. This article is a literature review of the available evidence on the initial hemodynamic support of the septic shock patients presenting to the emergency room or to the intensive care unit and the main interventions available to reach those targets, focusing on fluid and vasopressor therapy, blood transfusion and inotrope administration.

  18. Current concepts on hemodynamic support and therapy in septic shock.

    PubMed

    Rocha, Leonardo Lima; Pessoa, Camila Menezes Souza; Corrêa, Thiago Domingos; Pereira, Adriano José; de Assunção, Murillo Santucci Cesar; Silva, Eliézer

    2015-01-01

    Severe sepsis and septic shock represent a major healthcare challenge. Much of the improvement in mortality associated with septic shock is related to early recognition combined with timely fluid resuscitation and adequate antibiotics administration. The main goals of septic shock resuscitation include intravascular replenishment, maintenance of adequate perfusion pressure and oxygen delivery to tissues. To achieve those goals, fluid responsiveness evaluation and complementary interventions - i.e. vasopressors, inotropes and blood transfusion - may be necessary. This article is a literature review of the available evidence on the initial hemodynamic support of the septic shock patients presenting to the emergency room or to the intensive care unit and the main interventions available to reach those targets, focusing on fluid and vasopressor therapy, blood transfusion and inotrope administration.

  19. The hemodynamics of septic shock: a historical perspective.

    PubMed

    Feihl, Francois; Waeber, Bernard; Liaudet, Lucas

    2013-03-01

    In the late 19th century, it was already known that severe infections could be associated with cardiovascular collapse, a fact essentially attributed to cardiac failure. A major experimental work in the rabbit, published by Romberg and Pässler in 1899, shifted attention to disturbed peripheral vascular tone as the mechanism of hypotension in these conditions. In the first half of the 20th century, great progresses were made in the pathophysiologic understanding of hemorrhagic and traumatic shocks, while researchers devoted relatively little attention to septic shock. Progress in the hemodynamic understanding of septic shock resumed with the advent of critical care units. The hyperdynamic state was recognized in the late fifties and early sixties. The present short review ends with landmark studies by Max Harry Weil, demonstrating the importance of venous pooling, and John H. Siegel, which introduced the concept of deficient peripheral utilization of oxygen, inspiring later work on the microvascular disturbances of septic shock.

  20. Hemodynamic responses to functional activation accessed by optical imaging

    NASA Astrophysics Data System (ADS)

    Ni, Songlin; Li, Pengcheng; Yang, Yuanyuan; Lv, Xiaohua; Luo, Qingming

    2006-01-01

    A multi-wavelength light-emitting diode (LED) and laser diode (LD) based optical imaging system was developed to visualize the changes in cerebral blood flow, oxygenation following functional activation simultaneously in rodent cortex. The 2-D blood flow image was accessed by laser speckle contrast imaging, and the spectroscopic imaging of intrinsic signal was used for the calculation of oxyhemoglobin (HbO), deoxyhemoglobin (Hb) and total hemoglobin (HbT) concentration. The combination of spectroscopic imaging and laser speckle contrast imaging provides the capability to simultaneously investigate the spatial and temporal blood flow and hemoglobin concentration changes with high resolution, which may lead to a better understanding of the coupling between neuronal activation and vascular responses. The optical imaging system been built is compact and convenient to investigators. And it is reliable to acquire raw data. In present study, the hemodynamic responses to cortical spreading depression (CSD) in parietal cortex of ~-chloralose/urethan anesthetized rats were demonstrated.

  1. Echocardiographic Hemodynamic Monitoring in the Critically Ill Patient

    PubMed Central

    Romero-Bermejo, Francisco J; Ruiz-Bailén, Manuel; Guerrero-De-Mier, Manuel; López-Álvaro, Julián

    2011-01-01

    Echocardiography has shown to be an essential diagnostic tool in the critically ill patient's assessment. In this scenario the initial fluid therapy, such as it is recommended in the actual clinical guidelines, not always provides the desired results and maintains a considerable incidence of cardiorrespiratory insufficiency. Echocardiography can council us on these patients' clinical handling, not only the initial fluid therapy but also on the best-suited election of the vasoactive/inotropic treatment and the early detection of complications. It contributes as well to improving the etiological diagnosis, allowing one to know the heart performance with more precision. The objective of this manuscript is to review the more important parameters that can assist the intensivist in theragnosis of hemodynamically unstable patients. PMID:22758613

  2. Vascular tracers alter hemodynamics and airway pressure in anesthetized sheep

    SciTech Connect

    Albertine, K.H.; Staub, N.C.

    1986-11-01

    The technique of vascular labeling was developed to mark sites of increased microvascular permeability. We used the vascular labeling technique in anesthetized sheep and found that hemodynamics and airway pressure were adversely affected by intraarterial infusions of two vascular tracers. Monastral blue (nine sheep) immediately caused systemic arterial hypotension, pulmonary arterial hypertension, and bronchoconstriction. All three physiological responses were partially blocked by a cyclooxygenase inhibitor (indomethacin) but not by an H1-antihistamine (chlorpheniramine). Colloidal gold (nine sheep) caused immediate, but less dramatic, pulmonary arterial hypertension which was not attenuated by the blocking agents. We conclude that these two vascular tracers caused detrimental physiological side effects in sheep at the usual doses used to label injured microvessels in other species.

  3. Efficient hemodynamic event detection utilizing relational databases and wavelet analysis

    NASA Technical Reports Server (NTRS)

    Saeed, M.; Mark, R. G.

    2001-01-01

    Development of a temporal query framework for time-oriented medical databases has hitherto been a challenging problem. We describe a novel method for the detection of hemodynamic events in multiparameter trends utilizing wavelet coefficients in a MySQL relational database. Storage of the wavelet coefficients allowed for a compact representation of the trends, and provided robust descriptors for the dynamics of the parameter time series. A data model was developed to allow for simplified queries along several dimensions and time scales. Of particular importance, the data model and wavelet framework allowed for queries to be processed with minimal table-join operations. A web-based search engine was developed to allow for user-defined queries. Typical queries required between 0.01 and 0.02 seconds, with at least two orders of magnitude improvement in speed over conventional queries. This powerful and innovative structure will facilitate research on large-scale time-oriented medical databases.

  4. Hemodynamics of vascular 'waterfall': is the analogy justified?

    PubMed

    Badeer, H S; Hicks, J W

    1992-02-01

    The concept of 'vascular waterfall' has been used for collapsible vessels in different hemodynamic states which have little similarity to each other from a dynamic standpoint. Examples include (a) flow through large systemic veins entering the thorax, (b) flow through microvessels, such as pulmonary, cardiac, hepatic, cerebral, and (c) flow through the jugular vein of the giraffe. The dynamics of freely falling liquids (waterfall) as compared with flow through collapsible blood vessels (in vivo and in vitro) and in collapsible tubes are dissimilar in too many respects to justify analogy. The flow through collapsible tubes and blood vessels can be explained satisfactorily on the basis of elementary principles of fluid mechanics (Bernoulli-Poiseuille). Hence, the term waterfall as a metaphor is misleading and unjustified. We suggest that the use of the term be discontinued for describing vascular dynamics.

  5. In-vivo optical imaging and spectroscopy of cerebral hemodynamics

    NASA Astrophysics Data System (ADS)

    Zhou, Chao

    Functional optical imaging techniques, such as diffuse optical imaging and spectroscopy and laser speckle imaging (LSI), were used in research and clinical settings to measure cerebral hemodynamics. In this thesis, theoretical and experimental developments of the techniques and their in-vivo applications ranging from small animals to adult humans are demonstrated. Near infrared diffuse optical techniques non-invasively measure hemoglobin concentrations, blood oxygen saturation (diffuse reflectance spectroscopy, DRS) and blood flow (diffuse correlation spectroscopy, DCS) in deep tissues, e.g. brain. A noise model was derived for DCS measurements. Cerebral blood flow (CBF) measured with DCS was validated with arterial-spin-labeling MRI. Three-dimensional CBF tomography was obtained during cortical spreading depression from a rat using the optimized diffuse correlation tomographic method. Cerebral hemodynamics in newborn piglets after traumatic brain injury were continuously monitored optically for six hours to demonstrate the feasibility of using diffuse optical techniques as bedside patient monitors. Cerebral autoregulation in piglets and human stroke patients was demonstrated to be non-invasively assessable via the continuous DCS measurement. Significant differences of CBF responses to head-of-bead maneuvers were observed between the peri- and contra-infarct hemispheres in human stroke patients. A significant portion of patient population showed paradoxical CBF responses, indicating the importance of individualized stroke management. The development of a speckle noise model revealed the source of noise for LSI. LSI was then applied to study the acute functional recovery of the rat brain following transient brain ischemia. The spatial and temporal cerebral blood flow responses to functional stimulation were statistically quantified. The area of activation, and the temporal response to stimulation were found significantly altered by the ischemic insult, while the

  6. Optimal hemodynamic response model for functional near-infrared spectroscopy

    PubMed Central

    Kamran, Muhammad A.; Jeong, Myung Yung; Mannan, Malik M. N.

    2015-01-01

    Functional near-infrared spectroscopy (fNIRS) is an emerging non-invasive brain imaging technique and measures brain activities by means of near-infrared light of 650–950 nm wavelengths. The cortical hemodynamic response (HR) differs in attributes at different brain regions and on repetition of trials, even if the experimental paradigm is kept exactly the same. Therefore, an HR model that can estimate such variations in the response is the objective of this research. The canonical hemodynamic response function (cHRF) is modeled by two Gamma functions with six unknown parameters (four of them to model the shape and other two to scale and baseline respectively). The HRF model is supposed to be a linear combination of HRF, baseline, and physiological noises (amplitudes and frequencies of physiological noises are supposed to be unknown). An objective function is developed as a square of the residuals with constraints on 12 free parameters. The formulated problem is solved by using an iterative optimization algorithm to estimate the unknown parameters in the model. Inter-subject variations in HRF and physiological noises have been estimated for better cortical functional maps. The accuracy of the algorithm has been verified using 10 real and 15 simulated data sets. Ten healthy subjects participated in the experiment and their HRF for finger-tapping tasks have been estimated and analyzed. The statistical significance of the estimated activity strength parameters has been verified by employing statistical analysis (i.e., t-value > tcritical and p-value < 0.05). PMID:26136668

  7. Critical Transitions in Early Embryonic Aortic Arch Patterning and Hemodynamics

    PubMed Central

    Kowalski, William J.; Dur, Onur; Wang, Yajuan; Patrick, Michael J.; Tinney, Joseph P.; Keller, Bradley B.; Pekkan, Kerem

    2013-01-01

    Transformation from the bilaterally symmetric embryonic aortic arches to the mature great vessels is a complex morphogenetic process, requiring both vasculogenic and angiogenic mechanisms. Early aortic arch development occurs simultaneously with rapid changes in pulsatile blood flow, ventricular function, and downstream impedance in both invertebrate and vertebrate species. These dynamic biomechanical environmental landscapes provide critical epigenetic cues for vascular growth and remodeling. In our previous work, we examined hemodynamic loading and aortic arch growth in the chick embryo at Hamburger-Hamilton stages 18 and 24. We provided the first quantitative correlation between wall shear stress (WSS) and aortic arch diameter in the developing embryo, and observed that these two stages contained different aortic arch patterns with no inter-embryo variation. In the present study, we investigate these biomechanical events in the intermediate stage 21 to determine insights into this critical transition. We performed fluorescent dye microinjections to identify aortic arch patterns and measured diameters using both injection recordings and high-resolution optical coherence tomography. Flow and WSS were quantified with 3D computational fluid dynamics (CFD). Dye injections revealed that the transition in aortic arch pattern is not a uniform process and multiple configurations were documented at stage 21. CFD analysis showed that WSS is substantially elevated compared to both the previous (stage 18) and subsequent (stage 24) developmental time-points. These results demonstrate that acute increases in WSS are followed by a period of vascular remodeling to restore normative hemodynamic loading. Fluctuations in blood flow are one possible mechanism that impacts the timing of events such as aortic arch regression and generation, leading to the variable configurations at stage 21. Aortic arch variations noted during normal rapid vascular remodeling at stage 21 identify a

  8. Mathematical simulation of hemodynamical processes and medical technologies

    NASA Astrophysics Data System (ADS)

    Tsitsyura, Nadiya; Novyc'kyy, Victor V.; Lushchyk, Ulyana B.

    2001-06-01

    Vascular pathologies constitute a significant part of human's diseases and their rate tends to increase. Numerous investigations of brain blood flow in a normal condition and in a pathological one has created a new branch of modern medicine -- angioneurology. It combines the information on brain angioarchitecture and on blood supply in a normal condition and in a pathological one. Investigations of a disease's development constitute an important problem of a modern medicine. Cerebrum blood supply is regulated by arterial inflow and venous outflow, but, unfortunately, in the literature available arterial and venous beds are considered separately. This causes an one-sided interpretation of atherosclerotical and discirculatory encefalopathies. As arterial inflow and venous outflow are interrelated, it seems to be expedient to perform a complex estimation of arteriovenous interactions, prove a correlation dependence connection between the beds and find a dependence in a form of mathematical function. The results will be observed clearly in the graphs. There were 139 patients aged from 2 up to 70 examined in the 'Istyna' Scientific Medical Ultrasound Center by means of a Logidop 2 apparatus manufactured by Kranzbuhler, Germany using a technique of cerebral arteries and veins ultrasound location (invented and patented by Ulyana Lushchyk, State Patent of Ukraine N10262 of 19/07/1995). A clinical interpretation of the results obtained was performed. With the help of this technique and ultrasound Dopplerography the blood flow in major head and cervical arteries was investigated. While performing a visual graphic analysis we paid attention to the changes of carotid artery (CA), internal jugular vein (IJV) and supratrochlear artery's (STA) hemodynamical parameters. Generally accepted blood flow parameters: FS -- maximal systolic frequency and FD -- minimal diastolic frequency were measured. The correlation between different combinations of parameters in the vessels mentioned

  9. Hemodynamic Effect of Laser Therapy in Spontaneously Hypertensive Rats

    PubMed Central

    Tomimura, Suely; Silva, Bianca Passos Assumpção; Sanches, Iris Callado; Canal, Marina; Consolim-Colombo, Fernanda; Conti, Felipe Fernandes; Angelis, Katia De; Chavantes, Maria Cristina

    2014-01-01

    Systemic arterial hypertension (SAH) is considered to be the greatest risk factor for the development of neuro-cardiovascular pathologies, thus constituting a severe Public Health issue in the world. The Low-Level Laser Therapy (LLLT), or laser therapy, activates components of the cellular structure, therefore converting luminous energy into photochemical energy and leading to biophysical and biochemical reactions in the mitochondrial respiratory chain. The LLLT promotes cellular and tissue photobiomodulation by means of changes in metabolism, leading to molecular, cellular and systemic changes. The objective of this study was to analyze the action of low-level laser in the hemodynamic modulation of spontaneously hypertensive rats, in the long term. Animals (n = 16) were randomly divided into the Laser Group (n = 8), which received three weekly LLLT irradiations for seven weeks, and into the Sham Group (n = 8), which received three weekly simulations of laser for seven weeks, accounting for 21 applications in each group. After seven weeks, animals were cannulated by the implantation of a catheter in the left carotid artery. On the following day, the systemic arterial pressure was recorded. The Laser Group showed reduced levels of mean blood pressure, with statistically significant reduction (169 ± 4 mmHg* vs. 182 ± 4 mmHg from the Sham Group) and reduced levels of diastolic pressure (143 ± 4 mmHg* vs. 157 ± 3 mmHg from the Sham Group), revealing a 13 and 14 mmHg decrease, respectively. Besides, there was a concomitant important decline in heart rate (312 ± 14 bpm vs. 361 ± 13 bpm from the Sham Group). Therefore, laser therapy was able to produce hemodynamic changes, thus reducing pressure levels in spontaneously hypertensive rats. PMID:25211315

  10. Plethyzmography in assessment of hemodynamic results of pacemaker functions programming

    NASA Astrophysics Data System (ADS)

    Wojciechowski, Dariusz; Sionek, Piotr; Peczalski, Kazimierz; Janusek, Dariusz

    2011-01-01

    The paper presents potential role of plethyzmography in optimization of heart hemodynamic function during pacemaker programming. The assessment of optimal stroke volume in patients, with implanted dual chamber pacemaker (DDD), by plethyzmography was a goal of the study. The data were collected during pacing rhythm. 20 patients (8 female and 12 male, average 77.4+/-4.6 years) with dual chamber pacemaker (DDD) and with pacing rhythm during routine pacemaker control and study tests were incorporated in the study group. Hemodynamic parameters were assessed during modification of atrio-ventricular delay (AVD) for pacing rhythm of 70 bpm and 90 bpm. The time of atrioventricular was programmed with 20 ms steps within range 100-200 ms and data were recorded with two minutes delay between two consecutive measurements. Stroke volume (SV) and cardiac output (CO) were calculated from plethyzmographic signal by using Beatscope software (TNO Holand). Highest SV calculated for given pacing rhythm was named optimal stroke volume (OSV) and consequently highest cardiac output was named maximal cardiac output (MCO). The time of atrio-ventricular delay for OSV was named optimal atrioventricular delay (OAVD). The results have showed: mean values of OAVD for 70 bpm - 152+/-33 ms and for 90 bpm -149+/-35 ms, shortening of the mean OAVD time caused by increase of pacing rate from 70 bpm to 90 bpm what resulted in statistically significant decrease of OSV with not statistically significant increase of MCO. The analysis of consecutive patients revealed three types of response to increase of pacing rhythm: 1. typical-shortening of OAVD, 2. neutral-no change of OAVD and 3.atypical-lengthening of OAVD.

  11. Leonardo da Vinci and the first hemodynamic observations.

    PubMed

    Martins e Silva, J

    2008-02-01

    Leonardo da Vinci was a genius whose accomplishments and ideas come down to us today, five centuries later, with the freshness of innovation and the fascination of discovery. This brief review begins with a summary of Leonardo's life and a description of the most important works of art that he bequeathed us, and then concentrates on his last great challenge. There was a point at which Leonardo's passion for art gave way to the study of human anatomy, not only to improve his drawing but to go beyond what had been simply a representation of form to understand the underlying functioning. Among his many interests, we focus on his study of the heart and blood vessels, which he observed carefully in animals and human autopsies, and reproduced in drawings of great quality with annotations of astonishing acuteness. The experience that he had acquired from observing the flow of water in currents and around obstacles, and the conclusions that he drew concerning hydrodynamics, were central to his interpretation of the mechanisms of the heart and of blood flow, to which he devoted much of his time between 1508 and 1513. From these studies, immortalized in drawings of great clarity, come what are acknowledged to be the first hemodynamic records, in which Leonardo demonstrates the characteristics of blood flow in the aorta and great vessels and the importance of blood reflux and the formation of eddies in the sinus in aortic valve his assiduous and careful observations, and his subsequent deductions, Leonardo put forward detailed findings on hemodynamic questions that advanced technology has only recently enabled us to confirm.

  12. Hemodynamic effect of laser therapy in spontaneously hypertensive rats.

    PubMed

    Tomimura, Suely; Silva, Bianca Passos Assumpção; Sanches, Iris Callado; Canal, Marina; Consolim-Colombo, Fernanda; Conti, Felipe Fernandes; De Angelis, Katia; Chavantes, Maria Cristina

    2014-08-01

    Systemic arterial hypertension (SAH) is considered to be the greatest risk factor for the development of neuro-cardiovascular pathologies, thus constituting a severe Public Health issue in the world. The Low-Level Laser Therapy (LLLT), or laser therapy, activates components of the cellular structure, therefore converting luminous energy into photochemical energy and leading to biophysical and biochemical reactions in the mitochondrial respiratory chain. The LLLT promotes cellular and tissue photobiomodulation by means of changes in metabolism, leading to molecular, cellular and systemic changes. The objective of this study was to analyze the action of low-level laser in the hemodynamic modulation of spontaneously hypertensive rats, in the long term. Animals (n = 16) were randomly divided into the Laser Group (n = 8), which received three weekly LLLT irradiations for seven weeks, and into the Sham Group (n = 8), which received three weekly simulations of laser for seven weeks, accounting for 21 applications in each group. After seven weeks, animals were cannulated by the implantation of a catheter in the left carotid artery. On the following day, the systemic arterial pressure was recorded. The Laser Group showed reduced levels of mean blood pressure, with statistically significant reduction (169 ± 4 mmHg* vs. 182 ± 4 mmHg from the Sham Group) and reduced levels of diastolic pressure (143 ± 4 mmHg* vs. 157 ± 3 mmHg from the Sham Group), revealing a 13 and 14 mmHg decrease, respectively. Besides, there was a concomitant important decline in heart rate (312 ± 14 bpm vs. 361 ± 13 bpm from the Sham Group). Therefore, laser therapy was able to produce hemodynamic changes, thus reducing pressure levels in spontaneously hypertensive rats.

  13. Post-Treatment Hemodynamics of a Basilar Aneurysm and Bifurcation

    PubMed Central

    Ortega, J.; Hartman, J.; Rodriguez, J.; Maitland, D.

    2009-01-01

    To investigate whether or not a successful aneurysm treatment procedure can subject a parent artery to harmful hemodynamic stresses, computational fluid dynamics simulations are performed on a patient-specific basilar aneurysm and bifurcation before and after a virtual endovascular treatment. Prior to treatment, the aneurysm at systole is filled with a periodic train of vortex tubes, which form at the aneurysm neck and advect upwards into the dome. Following the treatment procedure however, the motion of the vortex train is inhibited by the aneurysm filling material, which confines the vortex tubes to the region beneath the aneurysm neck. Analysis of the post-treatment flow field indicates that the impingement of the basilar artery flow upon the treated aneurysm neck and the close proximity of a vortex tube to the parent artery wall increase the maximum wall shear stresses to values approximately equal to 50 Pa at systole. Calculation of the time-averaged wall shear stresses indicates that there is a 1.4 × 9 10−7 m2 area on the parent artery exposed to wall shear stresses greater than 37.9 Pa, a value shown by Fry [Circ. Res. 22(2):165–197, 1968] to cause severe damage to the endothelial cells that line the artery wall. The results of this study demonstrate that it is possible for a treatment procedure, which successfully isolates the aneurysm from the circulation and leaves no aneurysm neck remnant, to elevate the hemodynamic stresses to levels that are injurious to the artery wall. PMID:18629647

  14. Arterial stiffness, central hemodynamics, and cardiovascular risk in hypertension

    PubMed Central

    Palatini, Paolo; Casiglia, Edoardo; Gąsowski, Jerzy; Głuszek, Jerzy; Jankowski, Piotr; Narkiewicz, Krzysztof; Saladini, Francesca; Stolarz-Skrzypek, Katarzyna; Tikhonoff, Valérie; Van Bortel, Luc; Wojciechowska, Wiktoria; Kawecka-Jaszcz, Kalina

    2011-01-01

    This review summarizes several scientific contributions at the recent Satellite Symposium of the European Society of Hypertension, held in Milan, Italy. Arterial stiffening and its hemodynamic consequences can be easily and reliably measured using a range of noninvasive techniques. However, like blood pressure (BP) measurements, arterial stiffness should be measured carefully under standardized patient conditions. Carotid-femoral pulse wave velocity has been proposed as the gold standard for arterial stiffness measurement and is a well recognized predictor of adverse cardiovascular outcome. Systolic BP and pulse pressure in the ascending aorta may be lower than pressures measured in the upper limb, especially in young individuals. A number of studies suggest closer correlation of end-organ damage with central BP than with peripheral BP, and central BP may provide additional prognostic information regarding cardiovascular risk. Moreover, BP-lowering drugs can have differential effects on central aortic pressures and hemodynamics compared with brachial BP. This may explain the greater beneficial effect provided by newer antihypertensive drugs beyond peripheral BP reduction. Although many methodological problems still hinder the wide clinical application of parameters of arterial stiffness, these will likely contribute to cardiovascular assessment and management in future clinical practice. Each of the abovementioned parameters reflects a different characteristic of the atherosclerotic process, involving functional and/or morphological changes in the vessel wall. Therefore, acquiring simultaneous measurements of different parameters of vascular function and structure could theoretically enhance the power to improve risk stratification. Continuous technological effort is necessary to refine our methods of investigation in order to detect early arterial abnormalities. Arterial stiffness and its consequences represent the great challenge of the twenty-first century for

  15. Arterial stiffness, central hemodynamics, and cardiovascular risk in hypertension.

    PubMed

    Palatini, Paolo; Casiglia, Edoardo; Gąsowski, Jerzy; Głuszek, Jerzy; Jankowski, Piotr; Narkiewicz, Krzysztof; Saladini, Francesca; Stolarz-Skrzypek, Katarzyna; Tikhonoff, Valérie; Van Bortel, Luc; Wojciechowska, Wiktoria; Kawecka-Jaszcz, Kalina

    2011-01-01

    This review summarizes several scientific contributions at the recent Satellite Symposium of the European Society of Hypertension, held in Milan, Italy. Arterial stiffening and its hemodynamic consequences can be easily and reliably measured using a range of noninvasive techniques. However, like blood pressure (BP) measurements, arterial stiffness should be measured carefully under standardized patient conditions. Carotid-femoral pulse wave velocity has been proposed as the gold standard for arterial stiffness measurement and is a well recognized predictor of adverse cardiovascular outcome. Systolic BP and pulse pressure in the ascending aorta may be lower than pressures measured in the upper limb, especially in young individuals. A number of studies suggest closer correlation of end-organ damage with central BP than with peripheral BP, and central BP may provide additional prognostic information regarding cardiovascular risk. Moreover, BP-lowering drugs can have differential effects on central aortic pressures and hemodynamics compared with brachial BP. This may explain the greater beneficial effect provided by newer antihypertensive drugs beyond peripheral BP reduction. Although many methodological problems still hinder the wide clinical application of parameters of arterial stiffness, these will likely contribute to cardiovascular assessment and management in future clinical practice. Each of the abovementioned parameters reflects a different characteristic of the atherosclerotic process, involving functional and/or morphological changes in the vessel wall. Therefore, acquiring simultaneous measurements of different parameters of vascular function and structure could theoretically enhance the power to improve risk stratification. Continuous technological effort is necessary to refine our methods of investigation in order to detect early arterial abnormalities. Arterial stiffness and its consequences represent the great challenge of the twenty-first century for

  16. Additional hemodynamic measurements with an esophageal Doppler monitor: a preliminary report of compliance, force, kinetic energy, and afterload in the clinical setting.

    PubMed

    Atlas, Glen; Brealey, David; Dhar, Sunil; Dikta, Gerhard; Singer, Meryvn

    2012-12-01

    The esophageal Doppler monitor (EDM) is a minimally-invasive hemodynamic device which evaluates both cardiac output (CO), and fluid status, by estimating stroke volume (SV) and calculating heart rate (HR). The measurement of these parameters is based upon a continuous and accurate approximation of distal thoracic aortic blood flow. Furthermore, the peak velocity (PV) and mean acceleration (MA), of aortic blood flow at this anatomic location, are also determined by the EDM. The purpose of this preliminary report is to examine additional clinical hemodynamic calculations of: compliance (C), kinetic energy (KE), force (F), and afterload (TSVR(i)). These data were derived using both velocity-based measurements, provided by the EDM, as well as other contemporaneous physiologic parameters. Data were obtained from anesthetized patients undergoing surgery or who were in a critical care unit. A graphical inspection of these measurements is presented and discussed with respect to each patient's clinical situation. When normalized to each of their initial values, F and KE both consistently demonstrated more discriminative power than either PV or MA. The EDM offers additional applications for hemodynamic monitoring. Further research regarding the accuracy, utility, and limitations of these parameters is therefore indicated.

  17. Cerebrospinal Fluid Enhancement on Fluid Attenuated Inversion Recovery Images After Carotid Artery Stenting with Neuroprotective Balloon Occlusions: Hemodynamic Instability and Blood-Brain Barrier Disruption

    SciTech Connect

    Ogami, Ryo Nakahara, Toshinori; Hamasaki, Osamu; Araki, Hayato; Kurisu, Kaoru

    2011-10-15

    Purpose: A rare complication of carotid artery stenting (CAS), prolonged reversible neurological symptoms with delayed cerebrospinal fluid (CSF) space enhancement on fluid attenuated inversion recovery (FLAIR) images, is associated with blood-brain barrier (BBB) disruption. We prospectively identified patients who showed CSF space enhancement on FLAIR images. Methods: Nineteen patients-5 acute-phase and 14 scheduled-underwent 21 CAS procedures. Balloon catheters were navigated across stenoses, angioplasty was performed using a neuroprotective balloon, and stents were placed with after dilation under distal balloon protection. CSF space hyperintensity or obscuration on FLAIR after versus before CAS indicated CSF space enhancement. Correlations with clinical factors were examined. Results: CSF space was enhanced on FLAIR in 12 (57.1%) cases. Postprocedural CSF space enhancement was significantly related to age, stenosis rate, acute-stage procedure, and total occlusion time. All acute-stage CAS patients showed delayed enhancement. Only age was associated with delayed CSF space enhancement in scheduled CAS patients. Conclusions: Ischemic intolerance for severe carotid artery stenosis and temporary neuroprotective balloon occlusion, causing reperfusion injury, seem to be the main factors that underlie BBB disruption with delayed CSF space enhancement shortly after CAS, rather than sudden poststenting hemodynamic change. Our results suggest that factors related to hemodynamic instability or ischemic intolerance seem to be associated with post-CAS BBB vulnerability. Patients at risk for hemodynamic instability or with ischemic intolerance, which decrease BBB integrity, require careful management to prevent intracranial hemorrhagic and other post-CAS complications.

  18. Intersystem relationships of respiration and hemodynamics in the initial period of postural effects.

    PubMed

    Donina, Zh A; Lavrova, I N; Baranov, V M

    2013-07-01

    We studied the dependence of parameters of lung volumes and the elastic properties of the lungs on changes in the central hemodynamics occurring in the initial period of passive postural changes in cats. It was found that transition from the horizontal to head-up and head-down tilting was accompanied by opposite hemodynamic changes in the cranial and caudal parts of the body. Changes in lung compliance and functional residual capacity of the lungs were opposite and linearly depended on the intensity of hemodynamic shifts, which indicates passive character of the primary disorders primarily determined by a physical factor, gravity-dependent redistribution of body fluids.

  19. Hemodynamic Influences on Abdominal Aortic Aneurysm Disease: Application of Biomechanics to Aneurysm Pathophysiology

    PubMed Central

    Dua, Monica M.; Dalman, Ronald L.

    2010-01-01

    “Atherosclerotic” abdominal aortic aneurysms (AAAs) occur with the greatest frequency in the distal aorta. The unique hemodynamic environment of this area predisposes it to site-specific degenerative changes. In this review, we summarize the differential hemodynamic influences present along the length of the abdominal aorta, and demonstrate how alterations in aortic flow and wall shear stress modify AAA progression in experimental models. Improved understanding of aortic hemodynamic risk profiles provides an opportunity to modify patient activity patterns to minimize risk of aneurysmal degeneration. PMID:20347049

  20. Lateralization and Localization of Epilepsy Related Hemodynamic Foci Using Presurgical fMRI

    PubMed Central

    Zhang, Clara Huishi; Lu, Yunfeng; Brinkmann, Benjamin; Welker, Kirk; Worrell, Gregory; He, Bin

    2014-01-01

    Objective The aim was to develop a method for the purpose of localizing epilepsy related hemodynamic foci for patients suffering intractable focal epilepsy using task-free fMRI alone. Methods We studied three groups of subjects: patients with intractable focal epilepsy, healthy volunteers performing motor tasks, and healthy volunteers in resting state. We performed spatial independent component analysis (ICA) on the fMRI alone data and developed a set of IC selection criteria to identify epilepsy related ICs. The method was then tested in the two healthy groups. Results In seven out of the nine surgery patients, identified ICs were concordant with surgical resection. Our results were also consistent with presurgical evaluation of the remaining one patient without surgery and may explain why she was not suitable for resection treatment. In the motor task study of ten healthy subjects, our method revealed components with concordant spatial and temporal features as expected from the unilateral motor tasks. In the resting state study of seven healthy subjects, the method successfully rejected all components in four out of seven subjects as non-epilepsy related components. Conclusion These results suggest the lateralization and localization value of fMRI alone in presurgical evaluation for patients with intractable unilateral focal epilepsy. Significance The proposed method is noninvasive in nature and easy to implement. It has the potential to be incorporated in current presurgical workup for treating intractable focal epilepsy patients. PMID:24856460

  1. Effect of valsalva maneuver-induced hemodynamic changes on brain near-infrared spectroscopy measurements.

    PubMed

    Tsubaki, Atsuhiro; Kojima, Sho; Furusawa, Adriane Akemi; Onishi, Hideaki

    2013-01-01

    Near-infrared spectroscopy (NIRS) is widely used to measure human brain activation on the basis of cerebral hemodynamic response. However, a limitation of NIRS is that systemic changes influence the measured signals. The purpose of this study was to clarify the relationship between NIRS signals and blood pressure during the Valsalva maneuver. Nine healthy volunteers performed a 20-s Valsalva maneuver to change their blood pressure. Changes in oxyhemoglobin (O2Hb) concentration were measured with 34 channels with an inter-optode distance of 30 mm for deep-penetration measurements (deepO2Hb) and 9 channels with an inter-optode distance of 15 mm for shallow-penetration measurements (shallowO2Hb). The difference value (diffO2Hb) between deepO2Hb and shallowO2Hb was calculated. Mean arterial pressure (MAP) was recorded by volume clamping the finger pulse, and skin blood flow changes were measured at the forehead. Pearson's correlation coefficients between deepO2Hb and MAP, shallowO2Hb and MAP, and diffO2Hb and MAP were 0.893 (P < 0.01), 0.963 (P < 0.01), and 0.831 (P < 0.01), respectively. The results suggest that regional and systemic changes in the cardiovascular state strongly influence NIRS signals. PMID:23852482

  2. Hemodynamics analysis of patient-specific carotid bifurcation: a CFD model of downstream peripheral vascular impedance.

    PubMed

    Dong, Jingliang; Wong, Kelvin K L; Tu, Jiyuan

    2013-04-01

    The study of cardiovascular models was presented in this paper based on medical image reconstruction and computational fluid dynamics. Our aim is to provide a reality platform for the purpose of flow analysis and virtual intervention outcome predication for vascular diseases. By connecting two porous mediums with transient permeability at the downstream of the carotid bifurcation branches, a downstream peripheral impedance model was developed, and the effect of the downstream vascular bed impedance can be taken into consideration. After verifying its accuracy with a healthy carotid bifurcation, this model was implemented in a diseased carotid bifurcation analysis. On the basis of time-averaged wall shear stress, oscillatory shear index, and the relative residence time, fractions of abnormal luminal surface were highlighted, and the atherosclerosis was assessed from a hemodynamic point of view. The effect of the atherosclerosis on the transient flow division between the two branches because of the existence of plaque was also analysed. This work demonstrated that the proposed downstream peripheral vascular impedance model can be used for computational modelling when the outlets boundary conditions are not available, and successfully presented the potential of using medical imaging and numerical simulation to provide existing clinical prerequisites for diagnosis and therapeutic treatment.

  3. Effect of valsalva maneuver-induced hemodynamic changes on brain near-infrared spectroscopy measurements.

    PubMed

    Tsubaki, Atsuhiro; Kojima, Sho; Furusawa, Adriane Akemi; Onishi, Hideaki

    2013-01-01

    Near-infrared spectroscopy (NIRS) is widely used to measure human brain activation on the basis of cerebral hemodynamic response. However, a limitation of NIRS is that systemic changes influence the measured signals. The purpose of this study was to clarify the relationship between NIRS signals and blood pressure during the Valsalva maneuver. Nine healthy volunteers performed a 20-s Valsalva maneuver to change their blood pressure. Changes in oxyhemoglobin (O2Hb) concentration were measured with 34 channels with an inter-optode distance of 30 mm for deep-penetration measurements (deepO2Hb) and 9 channels with an inter-optode distance of 15 mm for shallow-penetration measurements (shallowO2Hb). The difference value (diffO2Hb) between deepO2Hb and shallowO2Hb was calculated. Mean arterial pressure (MAP) was recorded by volume clamping the finger pulse, and skin blood flow changes were measured at the forehead. Pearson's correlation coefficients between deepO2Hb and MAP, shallowO2Hb and MAP, and diffO2Hb and MAP were 0.893 (P < 0.01), 0.963 (P < 0.01), and 0.831 (P < 0.01), respectively. The results suggest that regional and systemic changes in the cardiovascular state strongly influence NIRS signals.

  4. Computed Tomography Perfusion Assessment of Radiation Therapy Effects on Spinal Cord Hemodynamics

    SciTech Connect

    Spampinato, Maria Vittoria; Bisdas, Sotirios; Sharma, Anand K.; McDonald, Daniel; Strojan, Primoz; Rumboldt, Zoran

    2010-07-01

    Purpose: We used computed tomography (CT) perfusion to evaluate the acute and late effect of radiation therapy (RT) on spinal cord (SC) hemodynamics in patients without symptoms of myelopathy. We hypothesized that SC perfusion could be acutely altered during RT. Methods and Materials: We analyzed neck CT perfusion studies of 36 head-and-neck cancer patients (N1), 16 of whom had previously undergone RT. In a separate group of 6 patients (N2), CT perfusion studies were obtained before RT, after 40 Gy, and after treatment completion. Results: In the N1 group, SC blood flow (BF), blood volume (BV), mean transit time (MTT), and capillary permeability (CP) maps were not significantly different between RT-treated and RT-naive patients. In the N2 group, BF and CP were significantly increased during treatment compared with the baseline and post-RT studies. Conclusions: Radiation therapy of the head and neck may cause transient perturbations of SC perfusion that seem to reverse after treatment. There are no definite chronic effects of RT on SC perfusion observeable at the typical doses administered during treatment of head and neck malignancies.

  5. [Comparison of clinical assessment and invasive evaluation of hemodynamic parameters in septic shock].

    PubMed

    Vucić, N; Pilas, V

    1995-06-01

    The authors compare, in this prospective study, the accuracy of their own clinical assessment of hemodynamic parameters and severity of disease with the findings obtained by right heart catheterization in 50 patients with septic shock. The purpose of the study was to determine whether Swan-Ganz catheter insertion was necessary in all patients with septic shock. As soon as the diagnosis was established, the value of pulmonary capillary wedge pressure was estimated, as well as presence or absence of pathological uptake/supply dependency in all patients. The latter is an excellent indicator of severity of disease. The accurate assessment was noted in 27 (54%) patients (1. investigator), and in 30 (60%) patients (2. investigator). The sensitivity of detection of pathological uptake/supply dependency amounted to 53% and 65%; specificity was 73% and 79%, respectively. The therapy was altered in 21 patients (42%) after catheter insertion. The results were tested with chi2-test (p < 0.01). The findings of this study warrant catheter insertion in patients with septic shock. PMID:8649145

  6. Hemodynamic simulation of blood flow in a new type of cardiac assist device named AVICENA.

    PubMed

    Alizadeh, Mansour; Tehrani, Pedram; Rahmani, Shahrokh

    2014-08-01

    The purpose of this study is to investigate the hemodynamic parameters of blood flow in a balloon as a part of a new type of cardiac assist device named AVICENA, which is implanted into the descending aorta to improve the strength of pumping blood flow in a poor-performing left ventricle. Balloon is inflated and deflated during diastole and systole, respectively. The longitudinal velocity of blood flow during balloon inflation and deflation has been considered. Through these investigations, the result reveals that the balloon inflation causes the blood flow to accelerate through the balloon and compensates the blood flow velocity required for the normal circulation system. When the balloon deflates, a reverse flow is generated and improves the perfusion of coronary arteries. Furthermore, the inlet pressure and acting force on the aortic valve for the healthy, unhealthy, and assisted heart have been compared. Result indicates that the force acting on the aortic valve has been considerably reduced for the assisted heart compare to the unhealthy or unassisted heart.

  7. Oxymetry Deep in Tissues With Low-Frequency Electron Paramagnetic Resonance

    NASA Astrophysics Data System (ADS)

    Halpern, Howard J.; Yu, Cheng; Peric, Miroslav; Barth, Eugene; Grdina, David J.; Teicher, Beverly A.

    1994-12-01

    We have measured the oxygen concentration in the body water of murine FSa and NFSa fibrosarcomas using a new method for quantitative oxygen concentration determination deep in the tissues of a living animal. The measurement uses unusually low-frequency electron paramagnetic spectroscopy sensitive to substrate 7 cm deep in tissue, partially deuterated spin probes (spin labels of molecular mass 195, approximating that of glucose) whose distribution compartment can be targeted with facile adduct substitution, and novel analytic techniques. We show that the water-compartment oxygen concentration of the tumors decreases as the tumor size increases and also shows a trend to decrease as radiobiologic hypoxia increases. An oxymetric spectral image of the tumor is presented. The technique will improve with larger human tissue samples. It provides the potential to quantitatively assess tissue hypoxia in ischemic or preischemic states in stroke and myocardial infarction. It will allow direct assessment of tumor hypoxia to determine the usefulness of radiation and chemotherapy adjuvants directed to hypoxic cell compartments.

  8. [ENDOTHELIAL MONOCYTEACTIVATING FACTOR II CANCELS OXIDATIVE STRESS, CONSTITUTIVE NOS UNCOUPLING AND INDUCED VIOLATIONS OF CARDIAC HEMODYNAMICS IN HYPERTENSION (PART II)].

    PubMed

    Dorofeyeva, N A; Kotsuruba, A V; Mogilnitskaya, L A; Malyna, A E; Kornelyuk, A I; Sagach, V F

    2015-01-01

    The purpose of this study was to investigate the effect of EMAP II on free radical state of the heart and blood vessels, to restore cNOS coupling and cardiac hemodynamics in spontaneously hypertensive rats. It was found that, due to the combined inhibition of oxidative and nitrosative stress, EMAP I quickly restores impaired in hypertension constitutive de novo synthesis of NO by restoring cNOS coupling. Restoration by EMAP II of constitutive de novo synthesis NO abolished cardiac and endothelial dysfunction in spontaneously hypertensive rats. In hypertension, the introduction of EMAP II helped to improve the performance of the pumping function of the heart (stroke volume increased by 18.2 %, cardiac output -22 %), an arterial stiffness decreased by 23.2 %, process of relaxation of the left ventricle improved, due to decreased in 4,7 times myocardial end-diastolic stiffness. PMID:26495731

  9. Venous hemodynamic changes in lower limb venous disease: the UIP consensus according to scientific evidence.

    PubMed

    Lee, Byung B; Nicolaides, Andrew N; Myers, Kenneth; Meissner, Mark; Kalodiki, Evi; Allegra, Claudio; Antignani, Pier L; Bækgaard, Niels; Beach, Kirk; Belcaro, Giovanni; Black, Stephen; Blomgren, Lena; Bouskela, Eliete; Cappelli, Massimo; Caprini, Joseph; Carpentier, Patrick; Cavezzi, Attilio; Chastanet, Sylvain; Christenson, Jan T; Christopoulos, Demetris; Clarke, Heather; Davies, Alun; Demaeseneer, Marianne; Eklöf, Bo; Ermini, Stefano; Fernández, Fidel; Franceschi, Claude; Gasparis, Antonios; Geroulakos, George; Sergio, Gianesini; Giannoukas, Athanasios; Gloviczki, Peter; Huang, Ying; Ibegbuna, Veronica; Kakkos, Stavros K; Kistner, Robert; Kölbel, Tilo; Kurstjens, Ralph L; Labropoulos, Nicos; Laredo, James; Lattimer, Christopher R; Lugli, Marzia; Lurie, Fedor; Maleti, Oscar; Markovic, Jovan; Mendoza, Erika; Monedero, Javier L; Moneta, Gregory; Moore, Hayley; Morrison, Nick; Mosti, Giovanni; Nelzén, Olle; Obermayer, Alfred; Ogawa, Tomohiro; Parsi, Kurosh; Partsch, Hugo; Passariello, Fausto; Perrin, Michel L; Pittaluga, Paul; Raju, Seshadri; Ricci, Stefano; Rosales, Antonio; Scuderi, Angelo; Slagsvold, Carl E; Thurin, Anders; Urbanek, Tomasz; M VAN Rij, Andre; Vasquez, Michael; Wittens, Cees H; Zamboni, Paolo; Zimmet, Steven; Ezpeleta, Santiago Z

    2016-06-01

    There are excellent guidelines for clinicians to manage venous diseases but few reviews to assess their hemodynamic background. Hemodynamic concepts that evolved in the past have largely remained unchallenged in recent decades, perhaps due to their often complicated nature and in part due to emergence of new diagnostic techniques. Duplex ultrasound scanning and other imaging techniques which evolved in the latter part of the 20th century have dominated investigation. They have greatly improved our understanding of the anatomical patterns of venous reflux and obstruction. However, they do not provide the physiological basis for understanding the hemodynamics of flow, pressure, compliance and resistance. Hemodynamic investigations appear to provide a better correlation with post-treatment clinical outcome and quality of life than ultrasound findings. There is a far better prospect for understanding the complete picture of the patient's disability and response to management by combining ultrasound with hemodynamic studies. Accordingly, at the instigation of Dr Angelo Scuderi, the Union Internationale de Phlebologie (UIP) executive board commissioned a large number of experts to assess all aspects of management for venous disease by evidence-based principles. These included experts from various member societies including the European Venous Forum (EVF), American Venous Forum (AVF), American College of Phlebology (ACP) and Cardiovascular Disease Educational and Research Trust (CDERT). Their aim was to confirm or dispel long-held hemodynamic principles and to provide a comprehensive review of venous hemodynamic concepts underlying the pathophysiology of lower limb venous disorders, their usefulness for investigating patients and the relevant hemodynamic changes associated with various forms of treatment. Chapter 1 is devoted to basic hemodynamic concepts and normal venous physiology. Chapter 2 presents the mechanism and magnitude of hemodynamic changes in acute deep vein

  10. Hemodynamic impact of cerebral aneurysm endovascular treatment devices: coils and flow diverters.

    PubMed

    Goubergrits, Leonid; Schaller, Jens; Kertzscher, Ulrich; Woelken, Thies; Ringelstein, Moritz; Spuler, Andreas

    2014-07-01

    Coils and flow diverters or stents are devices successfully used to treat cerebral aneurysms. Treatment aims to reduce intra-aneurysmal flow, thereby separating the aneurysmal sac from the blood circulation. The focus and this manuscript combining literature review and our original research is an analysis of changes in aneurysmal hemodynamics caused by endovascular treatment devices. Knowledge of post-treatment hemodynamics is a path to successful long-term treatment. Summarizing findings on hemodynamic impact of treatment devices, we conclude: coiling and stenting do not affect post-treatment intra-aneurysmal pressure, but significantly alter aneurysmal hemodynamics through flow reduction and a change in flow structure. The impact of treatment devices on aneurysmal flow depends, however, on a set of parameters including device geometry, course of placement, parent vessel and aneurysm geometry.

  11. Transitional cardiovascular physiology and comprehensive hemodynamic monitoring in the neonate: relevance to research and clinical care.

    PubMed

    Azhibekov, Timur; Noori, Shahab; Soleymani, Sadaf; Seri, Istvan

    2014-02-01

    A thorough understanding of developmental cardiovascular physiology is essential for early recognition of cardiovascular compromise, selective screening of at-risk groups of neonates, and individualized management using pathophysiology-targeted interventions. Although we have gained a better understanding of the physiology and pathophysiology of postnatal cardiovascular transition over the past decade with the use of sophisticated methods to study neonatal hemodynamics, most aspects of neonatal hemodynamics remain incompletely understood. In addition, targeted therapeutic interventions of neonatal hemodynamic compromise have not been shown to improve mortality and clinically relevant outcomes. However, the recent development of comprehensive hemodynamic monitoring systems capable of non-invasive, continuous and simultaneous bedside assessment of cardiac output, organ blood flow, microcirculation, and tissue oxygen delivery has made sophisticated analysis of the obtained physiologic data possible and has created new research opportunities with the potential of direct implications to patient care.

  12. Cerebral versus systemic hemodynamics during graded orthostatic stress in humans

    NASA Technical Reports Server (NTRS)

    Levine, B. D.; Giller, C. A.; Lane, L. D.; Buckey, J. C.; Blomqvist, C. G.

    1994-01-01

    BACKGROUND: Orthostatic syncope is usually attributed to cerebral hypoperfusion secondary to systemic hemodynamic collapse. Recent research in patients with neurocardiogenic syncope has suggested that cerebral vasoconstriction may occur during orthostatic hypotension, compromising cerebral autoregulation and possibly contributing to the loss of consciousness. However, the regulation of cerebral blood flow (CBF) in such patients may be quite different from that of healthy individuals, particularly when assessed during the rapidly changing hemodynamic conditions associated with neurocardiogenic syncope. To be able to interpret the pathophysiological significance of these observations, a clear understanding of the normal responses of the cerebral circulation to orthostatic stress must be obtained, particularly in the context of the known changes in systemic and regional distributions of blood flow and vascular resistance during orthostasis. Therefore, the specific aim of this study was to examine the changes that occur in the cerebral circulation during graded reductions in central blood volume in the absence of systemic hypotension in healthy humans. We hypothesized that cerebral vasoconstriction would occur and CBF would decrease due to activation of the sympathetic nervous system. We further hypothesized, however, that the magnitude of this change would be small compared with changes in systemic or skeletal muscle vascular resistance in healthy subjects with intact autoregulation and would be unlikely to cause syncope without concomitant hypotension. METHODS AND RESULTS: To test this hypothesis, we studied 13 healthy men (age, 27 +/- 7 years) during progressive lower body negative pressure (LBNP). We measured systemic flow (Qc is cardiac output; C2H2 rebreathing), regional forearm flow (FBF; venous occlusion plethysmography), and blood pressure (BP; Finapres) and calculated systemic (SVR) and forearm (FVR) vascular resistances. Changes in brain blood flow were

  13. [Effect of complex sanatorium treatment including magnetotherapy on hemodynamics in patients with arterial hypertension].

    PubMed

    Efremushkin, G G; Duruda, N V

    2003-01-01

    Forty nine patients with arterial hypertension of stage I-II received combined sanatorium treatment. Of them, 21 had adjuvant total magnetotherapy. All the patients were examined for parameters of central, cerebral hemodynamics and microcirculation. The adjuvant magnetotherapy produced a beneficial effect on hypertension: clinical symptoms attenuated, arterial pressure became more stable, hemodynamics improved, duration of hospitalization reduced, requirement in hypotensive drugs diminished. PMID:12852007

  14. Vascular and Renal Hemodynamic Changes after Renal Denervation

    PubMed Central

    Ott, Christian; Janka, Rolf; Schmid, Axel; Titze, Stephanie; Ditting, Tilmann; Sobotka, Paul A.; Veelken, Roland; Uder, Michael

    2013-01-01

    Summary Background and objectives Renal denervation (RDN) has been shown to be effective in reducing BP in treatment-resistant hypertension. Measurement of the renal and sympathetic activity revealed a decrease in sympathetic drive to the kidney and small resistance vessels after RDN. However, the consequences on renal perfusion and renal vascular resistance (RVR), as well as central hemodynamics, are unknown. Design, setting, participants, & measurements Nineteen patients with treatment-resistant hypertension (office BP≥140/90 mmHg, despite at least three antihypertensive drugs [including a diuretic], and diagnosis confirmed by 24-hour ambulatory BP monitoring) underwent RDN between January and October 2011. Renal perfusion and RVR were noninvasively assessed by magnetic resonance imaging with arterial spin labeling, and renal function was assessed by estimating GFR before (day −1), after (day +1), and again after 3 months of RDN. Central hemodynamics was assessed using pulse wave analysis at day −1 and after 6 months of RDN. Results Peripheral office BP (systolic, 158±26 versus 142±23 mmHg, P=0.002; diastolic, 83±13 versus 76±9 mmHg, P=0.02) and mean systolic 24-hour ambulatory BP (159±17 versus 152±17 mmHg, P=0.02) were significantly reduced 6 months after RDN. Renal perfusion was not statistically different between day −1 and day +1 (256.8 [interquartile range (IQR), 241–278] versus 263.4 [IQR, 252–277] ml/min per 100 g; P=0.17) as well as after 3 months (256.8 [IQR, 241–278] versus 261.2 [IQR, 240–285] ml/min per 100 g; P=0.27) after RDN. RVR dropped (432.1 [IQR, 359–525] versus 390.6 [IQR, 338–461] AU; P=0.02), whereas renal function was not statistically different at any time point. Central systolic BP (145±31 versus 131±28 mmHg; P=0.009), diastolic BP (85±18 versus 80±14 mmHg; P=0.03), and central pulse pressure (61±18 versus 52±18 mmHg; P=0.02) were significantly reduced 6 months after RDN. Central augmentation index (24±8

  15. Systemic hemodynamics in advanced cirrhosis: Concerns during perioperative period of liver transplantation.

    PubMed

    Hori, Tomohide; Ogura, Yasuhiro; Onishi, Yasuharu; Kamei, Hideya; Kurata, Nobuhiko; Kainuma, Motoshi; Takahashi, Hideo; Suzuki, Shogo; Ichikawa, Takashi; Mizuno, Shoko; Aoyama, Tadashi; Ishida, Yuki; Hirai, Takahiro; Hayashi, Tomoko; Hasegawa, Kazuko; Takeichi, Hiromu; Ota, Atsunobu; Kodera, Yasuhiro; Sugimoto, Hiroyuki; Iida, Taku; Yagi, Shintaro; Taniguchi, Kentaro; Uemoto, Shinji

    2016-09-01

    Advanced liver cirrhosis is usually accompanied by portal hypertension. Long-term portal hypertension results in various vascular alterations. The systemic hemodynamic state in patients with cirrhosis is termed a hyperdynamic state. This peculiar hemodynamic state is characterized by an expanded blood volume, high cardiac output, and low total peripheral resistance. Vascular alterations do not disappear even long after liver transplantation (LT), and recipients with cirrhosis exhibit a persistent systemic hyperdynamic state even after LT. Stability of optimal systemic hemodynamics is indispensable for adequate portal venous flow (PVF) and successful LT, and reliable parameters for optimal systemic hemodynamics and adequate PVF are required. Even a subtle disorder in systemic hemodynamics is precisely indicated by the balance between cardiac output and blood volume. The indocyanine green (ICG) kinetics reflect the patient's functional hepatocytes and effective PVF, and PVF is a major determinant of the ICG elimination constant (kICG) in the well-preserved allograft. The kICG value is useful to set the optimal PVF during living-donor LT and to evaluate adequate PVF after LT. Perioperative management has a large influence on the postoperative course and outcome; therefore, key points and unexpected pitfalls for intensive management are herein summarized. Transplant physicians should fully understand the peculiar systemic hemodynamic behavior in LT recipients with cirrhosis and recognize the critical importance of PVF after LT. PMID:27660671

  16. Image-based modeling of the hemodynamics in cerebral arterial trees

    NASA Astrophysics Data System (ADS)

    Mut, Fernando; Wright, Susan; Putman, Christopher; Ascoli, Giorgio; Cebral, Juan

    2009-02-01

    Knowledge of the hemodynamics in normal arterial trees of the brain is important to better understand the mechanisms responsible for the initiation and progression of cerebrovascular diseases. Information about the baseline values of hemodynamic variables such as velocity magnitudes, swirling flows, wall shear stress, pressure drops, vascular resistances, etc. is important for characterization of the normal hemodynamics and comparison with pathological states such as aneurysms and stenoses. This paper presents image-based computational hemodynamics models of cerebral arterial trees constructed from magnetic resonance angiography (MRA) images. The construction of large models of cerebral arterial trees is challenging because of the following main reasons: a) it is necessary to acquire high resolution angiographic images covering the entire brain, b) it is necessary to construct topologically correct and geometrically accurate watertight models of the vasculature, and c) the models typically result in large computational grids which make the calculations computationally demanding. This paper presents a methodology to model the hemodynamics in the brain arterial network that combines high resolution MRA at 3T, a vector representation of the vascular structures based on semi-manual segmentation, and a novel algorithm to solve the incompressible flow equations efficiently in tubular geometries. These techniques make the study of the hemodynamics in the cerebral arterial network practical.

  17. Systemic hemodynamics in advanced cirrhosis: Concerns during perioperative period of liver transplantation

    PubMed Central

    Hori, Tomohide; Ogura, Yasuhiro; Onishi, Yasuharu; Kamei, Hideya; Kurata, Nobuhiko; Kainuma, Motoshi; Takahashi, Hideo; Suzuki, Shogo; Ichikawa, Takashi; Mizuno, Shoko; Aoyama, Tadashi; Ishida, Yuki; Hirai, Takahiro; Hayashi, Tomoko; Hasegawa, Kazuko; Takeichi, Hiromu; Ota, Atsunobu; Kodera, Yasuhiro; Sugimoto, Hiroyuki; Iida, Taku; Yagi, Shintaro; Taniguchi, Kentaro; Uemoto, Shinji

    2016-01-01

    Advanced liver cirrhosis is usually accompanied by portal hypertension. Long-term portal hypertension results in various vascular alterations. The systemic hemodynamic state in patients with cirrhosis is termed a hyperdynamic state. This peculiar hemodynamic state is characterized by an expanded blood volume, high cardiac output, and low total peripheral resistance. Vascular alterations do not disappear even long after liver transplantation (LT), and recipients with cirrhosis exhibit a persistent systemic hyperdynamic state even after LT. Stability of optimal systemic hemodynamics is indispensable for adequate portal venous flow (PVF) and successful LT, and reliable parameters for optimal systemic hemodynamics and adequate PVF are required. Even a subtle disorder in systemic hemodynamics is precisely indicated by the balance between cardiac output and blood volume. The indocyanine green (ICG) kinetics reflect the patient’s functional hepatocytes and effective PVF, and PVF is a major determinant of the ICG elimination constant (kICG) in the well-preserved allograft. The kICG value is useful to set the optimal PVF during living-donor LT and to evaluate adequate PVF after LT. Perioperative management has a large influence on the postoperative course and outcome; therefore, key points and unexpected pitfalls for intensive management are herein summarized. Transplant physicians should fully understand the peculiar systemic hemodynamic behavior in LT recipients with cirrhosis and recognize the critical importance of PVF after LT.

  18. Systemic hemodynamics in advanced cirrhosis: Concerns during perioperative period of liver transplantation

    PubMed Central

    Hori, Tomohide; Ogura, Yasuhiro; Onishi, Yasuharu; Kamei, Hideya; Kurata, Nobuhiko; Kainuma, Motoshi; Takahashi, Hideo; Suzuki, Shogo; Ichikawa, Takashi; Mizuno, Shoko; Aoyama, Tadashi; Ishida, Yuki; Hirai, Takahiro; Hayashi, Tomoko; Hasegawa, Kazuko; Takeichi, Hiromu; Ota, Atsunobu; Kodera, Yasuhiro; Sugimoto, Hiroyuki; Iida, Taku; Yagi, Shintaro; Taniguchi, Kentaro; Uemoto, Shinji

    2016-01-01

    Advanced liver cirrhosis is usually accompanied by portal hypertension. Long-term portal hypertension results in various vascular alterations. The systemic hemodynamic state in patients with cirrhosis is termed a hyperdynamic state. This peculiar hemodynamic state is characterized by an expanded blood volume, high cardiac output, and low total peripheral resistance. Vascular alterations do not disappear even long after liver transplantation (LT), and recipients with cirrhosis exhibit a persistent systemic hyperdynamic state even after LT. Stability of optimal systemic hemodynamics is indispensable for adequate portal venous flow (PVF) and successful LT, and reliable parameters for optimal systemic hemodynamics and adequate PVF are required. Even a subtle disorder in systemic hemodynamics is precisely indicated by the balance between cardiac output and blood volume. The indocyanine green (ICG) kinetics reflect the patient’s functional hepatocytes and effective PVF, and PVF is a major determinant of the ICG elimination constant (kICG) in the well-preserved allograft. The kICG value is useful to set the optimal PVF during living-donor LT and to evaluate adequate PVF after LT. Perioperative management has a large influence on the postoperative course and outcome; therefore, key points and unexpected pitfalls for intensive management are herein summarized. Transplant physicians should fully understand the peculiar systemic hemodynamic behavior in LT recipients with cirrhosis and recognize the critical importance of PVF after LT. PMID:27660671

  19. Sub-band denoising and spline curve fitting method for hemodynamic measurement in perfusion MRI

    NASA Astrophysics Data System (ADS)

    Lin, Hong-Dun; Huang, Hsiao-Ling; Hsu, Yuan-Yu; Chen, Chi-Chen; Chen, Ing-Yi; Wu, Liang-Chi; Liu, Ren-Shyan; Lin, Kang-Ping

    2003-05-01

    In clinical research, non-invasive MR perfusion imaging is capable of investigating brain perfusion phenomenon via various hemodynamic measurements, such as cerebral blood volume (CBV), cerebral blood flow (CBF), and mean trasnit time (MTT). These hemodynamic parameters are useful in diagnosing brain disorders such as stroke, infarction and periinfarct ischemia by further semi-quantitative analysis. However, the accuracy of quantitative analysis is usually affected by poor signal-to-noise ratio image quality. In this paper, we propose a hemodynamic measurement method based upon sub-band denoising and spline curve fitting processes to improve image quality for better hemodynamic quantitative analysis results. Ten sets of perfusion MRI data and corresponding PET images were used to validate the performance. For quantitative comparison, we evaluate gray/white matter CBF ratio. As a result, the hemodynamic semi-quantitative analysis result of mean gray to white matter CBF ratio is 2.10 +/- 0.34. The evaluated ratio of brain tissues in perfusion MRI is comparable to PET technique is less than 1-% difference in average. Furthermore, the method features excellent noise reduction and boundary preserving in image processing, and short hemodynamic measurement time.

  20. Slow spontaneous hemodynamic oscillations during sleep measured with near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Virtanen, Jaakko; Näsi, Tiina; Noponen, Tommi; Toppila, Jussi; Salmi, Tapani; Ilmoniemi, Risto J.

    2011-07-01

    Spontaneous cerebral hemodynamic oscillations below 100 mHz reflect the level of cerebral activity, modulate hemodynamic responses to tasks and stimuli, and may aid in detecting various pathologies of the brain. Near-infrared spectroscopy (NIRS) is ideally suited for both measuring spontaneous hemodynamic oscillations and monitoring sleep, but little research has been performed to combine these two applications. We analyzed 30 all-night NIRS-electroencephalography (EEG) sleep recordings to investigate spontaneous hemodynamic activity relative to sleep stages determined by polysomnography. Signal power of hemodynamic oscillations in the low-frequency (LF, 40-150 mHz) and very-low-frequency (VLF, 3-40 mHz) bands decreased in slow-wave sleep (SWS) compared to light sleep (LS) and rapid-eye-movement (REM) sleep. No statistically significant (p < 0.05) differences in oscillation power between LS and REM were observed. However, the period of VLF oscillations around 8 mHz increased in REM sleep in line with earlier studies with other modalities. These results increase our knowledge of the physiology of sleep, complement EEG data, and demonstrate the applicability of NIRS to studying spontaneous hemodynamic fluctuations during sleep.

  1. Glomerular hemodynamics in persistent renovascular hypertension in the rat.

    PubMed

    Herrera-Acosta, J; Gabbai, F; Franco, M; Tapia, E; Linfa, G; Díaz, L; Campos, J

    1983-01-01

    We studied the glomerular hemodynamics and activity of the tubuloglomerular feedback system (TGFS) in Wistar rats with persistent hypertension 60 days after removal of the clipped kidney in the Goldblatt (two-kidney, one clip) hypertension model. Ten hypertensive rats (HBP) were compared with 12 normotensive ones (NBP). Micropuncture studies revealed that values for the single nephron glomerular filtration rate (SNGFR), glomerular plasma flow (QA), and afferent oncotic pressure (PAR.A) were similar in both groups, whereas glomerular capillary pressure (PGC) and effective filtration pressure (EFP) were higher in the HBP group (p less than 0.05). A slight but insignificant increase in afferent resistance was present in the HBP group. A positive correlation was found between mean arterial pressure and stop flow pressure (SFP) (r = 0.64, p less than 0.05) but not with SNGFR, suggesting a reduction in the ultrafiltration coefficient in hypertensive rats. This was further supported by studies of the activity of the TGFS, which demonstrated that interrupting flow to the macula densa was followed by a smaller increment in SNGFR in HBP, in spite of a similar rise in SFP. The mechanism responsible for decreasing glomerular permeability is unknown but could be related to structural changes in glomerular capillary or to an increase in intrarenal angiotensin II, as has been demonstrated previously in this model. It is suggested that these adaptations occurring in the kidney exposed to hypertension can contribute to the maintenance of elevated arterial pressure after removing the stenotic kidney.

  2. Varicose veins of lower extremities, hemodynamics and treatment methods.

    PubMed

    Chwała, Maciej; Szczeklik, Wojciech; Szczeklik, Michał; Aleksiejew-Kleszczyński, Tomasz; Jagielska-Chwała, Maria

    2015-01-01

    Chronic venous insufficiency is one of the most common disorders of the vascular system, affecting approximately 50% of adults. If left untreated it can lead to a number of complications, including venous ulceration and venous thrombosis. This review paper outlines the epidemiology and ethiopathogenesis of the disease with regard to hemodynamics and microcirculation disturbances. It describes the medical treatment as well as the traditional surgical approach to varicose veins (with several modifications of this technique), and its limitations and contraindications. Furthermore, it discusses a number of new, minimally invasive treatment methods, namely thermal in form (radiofrequency ablation, endovenous laser ablation, steam ablation) and nonthermal (sclerotherapy, echosclerotherapy, Clarivein, Sapheon). For each method, there is a brief historical overview, a description of its mechanism of action, and its indications and limitations. The results of comparative studies on individual treatment methods as well as meta-analyses on this topic are briefly discussed. This paper highlights the progressive trend towards minimally invasive methods and attempts to predict the further development.

  3. Hemodynamic measurements for evaluating vasovagal syncope in the emergency department

    PubMed Central

    Chan, Stewart Siu-Wa; Mo, Junrong; Graham, Colin Alexander; Rainer, Timothy Hudson

    2015-01-01

    Syncope is a sudden and transient loss of consciousness and postural tone, with spontaneous recovery without medical intervention. It accounts for 1.0% to 1.5% of emergency department (ED) visits and up to 6% of hospital admissions. Vasovagal syncope may be the cause of syncope in 21% to 40% of cases. A 53-year-old Chinese woman was brought to the ED by ambulance after a near-syncope episode while performing gentle morning exercises. She was hypotensive and bradycardic in the ambulance. Upon arrival at the ED, her blood pressure was 89/61 mmHg. The use of a Doppler cardiac output monitor readily demonstrated that the patient’s systemic vascular resistance was reduced, with cardiac output at the lower limit of the normal range. These hemodynamic data were useful in supporting the diagnosis of vasovagal syncope; they helped in the risk stratification of our patient with syncope, and guided the management and subsequent disposition decision.

  4. Hemodynamic effects of plasma exchange in septic patients: preliminary report.

    PubMed

    Berlot, G; Gullo, A; Fasiolo, S; Serra, L; Silvestri, L; Wörz, M

    1997-01-01

    To assess the effects of plasma exchange on the hemodynamic performance of septic patients, we studied 12 septic patients (11 males and 1 female, age range 19-64, mean 39 +/- 17 years). After cardiovascular stabilization, plasma exchange was performed in the spontaneous mode via a femorofemoral arteriovenous shunt; during the treatment the infusion rate of cardiovascular drugs and the mechanical ventilation setting were not modified. Heart rate, pulmonary artery occlusion pressure, and peripheral vascular resistance did not change significantly. The stroke volume index increased significantly (from 49 +/- 9 to 60 +/- 9 ml/min/m2; p < 0.05) as well as the cardiac index (from 5.5 +/- 1.2 to 6.3 +/- 0.8 liters/min/m2, the oxygen delivery (from 785 +/- 166 to 872 +/- 118 ml/min/m2; p < 0.05), and the left ventricular stroke work index/pulmonary artery occlusion pressure ratio (from 4.03 +/- 1.92 to 5.07 +/- 2.54; p < 0.05). The oxygen consumption did not change. Four patients survived. In conclusion, in our patients plasma exchange was associated with an improvement in cardiac function, possibly due to the elimination of some sepsis mediator(s) with negative inotropic properties. PMID:9096906

  5. Effects of adenosine infusion into renal interstitium on renal hemodynamics

    SciTech Connect

    Pawlowska, D.; Granger, J.P.; Knox, F.G.

    1987-04-01

    This study was designed to investigate the hemodynamic effects of exogenous adenosine in the interstitium of the rat kidney. Adenosine or its analogues were infused into the renal interstitium by means of chronically implanted capsules. In fusion of adenosine decreased glomerular filtration rate (GFR) from 0.81 +/- 0.06 to 0.37 +/- 0.06 ml/min while having no effect on renal blood flow (RBF). The metabolically stable analogue, 2-chloradenosine (2-ClAdo), decreased GFR from 0.73 +/- 0.07 to 021 +/- 0.06 ml/min. Interstitial infusion of theophylline, an adenosine receptor antagonist, completely abolished the effects of adenosine and 2-ClAdo on GFR. The distribution of adenosine, when infused into the renal interstitium, was determined using radiolabeled 5'-(N-ethyl)-carboxamidoadenosine (NECA), a metabolically stable adenosine agonist. After continuous infusion, (/sup 3/H)NECA was distributed throughout the kidney. The effects of NECA to reduce GFR were similar to those of adenosine and 2-ClAdo. They conclude that increased levels of adenosine in the renal interstitium markedly decrease GFR without affecting RBF in steady-state conditions. The marked effects of adenosine agonists during their infusion into the renal interstitium and the complete blockade of these effects by theophylline suggest an extracellular action of adenosine.

  6. Hemodynamic forces regulate developmental patterning of atrial conduction.

    PubMed

    Bressan, Michael C; Louie, Jonathan D; Mikawa, Takashi

    2014-01-01

    Anomalous action potential conduction through the atrial chambers of the heart can lead to severe cardiac arrhythmia. To date, however, little is known regarding the mechanisms that pattern proper atrial conduction during development. Here we demonstrate that atrial muscle functionally diversifies into at least two heterogeneous subtypes, thin-walled myocardium and rapidly conducting muscle bundles, during a developmental window just following cardiac looping. During this process, atrial muscle bundles become enriched for the fast conduction markers Cx40 and Nav1.5, similar to the precursors of the fast conduction Purkinje fiber network located within the trabeculae of the ventricles. In contrast to the ventricular trabeculae, however, atrial muscle bundles display an increased proliferation rate when compared to the surrounding myocardium. Interestingly, mechanical loading of the embryonic atrial muscle resulted in an induction of Cx40, Nav1.5 and the cell cycle marker Cyclin D1, while decreasing atrial pressure via in vivo ligation of the vitelline blood vessels results in decreased atrial conduction velocity. Taken together, these data establish a novel model for atrial conduction patterning, whereby hemodynamic stretch coordinately induces proliferation and fast conduction marker expression, which in turn promotes the formation of large diameter muscle bundles to serve as preferential routes of conduction.

  7. Adrenergic Metabolic and Hemodynamic Effects of Octopamine in the Liver

    PubMed Central

    de Oliveira, Andrea Luiza; de Paula, Mariana Nascimento; Comar, Jurandir Fernando; Vilela, Vanessa Rodrigues; Peralta, Rosane Marina; Bracht, Adelar

    2013-01-01

    The fruit extracts of Citrus aurantium (bitter orange) are traditionally used as weight-loss products and as appetite suppressants. A component of these extracts is octopamine, which is an adrenergic agent. Weight-loss and adrenergic actions are always related to metabolic changes and this work was designed to investigate a possible action of octopamine on liver metabolism. The isolated perfused rat liver was used to measure catabolic and anabolic pathways and hemodynamics. Octopamine increased glycogenolysis, glycolysis, oxygen uptake, gluconeogenesis and the portal perfusion pressure. Octopamine also accelerated the oxidation of exogenous fatty acids (octanoate and oleate), as revealed by the increase in 14CO2 production derived from 14C labeled precursors. The changes in glycogenolysis, oxygen uptake and perfusion pressure were almost completely abolished by α1-adrenergic antagonists. The same changes were partly sensitive to the β-adrenergic antagonist propranolol. It can be concluded that octopamine accelerates both catabolic and anabolic processes in the liver via adrenergic stimulation. Acceleration of oxygen uptake under substrate-free perfusion conditions also means acceleration of the oxidation of endogenous fatty acids, which are derived from lipolysis. All these effects are compatible with an overall stimulating effect of octopamine on metabolism, which is compatible with its reported weight-loss effects in experimental animals. PMID:24196353

  8. Hemodynamic and alveolar protein studies in noncardiac pulmonary edema.

    PubMed

    Gelb, A F; Klein, E

    1976-11-01

    Hemodynamic data were obtained within 15 hours of admission in 11 previously healthy patients (20 to 51 years of age, 7 men and 4 women) who had developed transient, reversible pulmonary edema without cardiac dilation in association with near-death from freshwater drowning (2 cases), pentobarbital overdose, heroin overdose (2 cases), smoke inhalation, chest trauma, sepsis (2 cases), pancreatitis, or prolonged abdominal surgery with suspected sepsis. Using a balloon-tipped flow-directed catheter, the pulmonary artery systolic/diastolic pressures (in mm Hg) were 25/12, 22/9, 31/11, 26/15, 20/10, 35/15, 40/15, 32/18, 20/10, 24/10, and 20/7; the corresponding pulmonary capillary wedge pressures (in mm Hg) were 8, 9, 6, 14, 6, 6, 15, 15, 10, 10, and 5, respectively. Plasma colloidal osmotic pressures measured in the latter 5 cases were 26, 18, 18, 18, and 15 mm Hg, respectively. In addition, the protein content of the alveolar fluid was 5.1, 3.4, 4.0, and 7.1 g per 100 ml in 4 patients. The concentration and distribution of the protein in plasma and alveolar fluid were very similar. These findings provide strong efidence that altered capillary permeability is responsible for the pulmonary edema.

  9. Adverse pacemaker hemodynamics evaluated by pulmonary venous flow monitoring.

    PubMed

    Stierle, U; Krüger, D; Mitusch, R; Potratz, J; Taubert, G; Sheikhzadeh, A

    1995-11-01

    The pacemaker syndrome refers to symptoms and signs in the pacemaker patient caused by an inadequate timing of atrial and ventricular contractions. The lack of normal atrioventricular synchrony may result in a decreased cardiac output and venous cannon A waves. The objective of this study was to define the left atrial and pulmonary venous flow response to ventricular pacing in a group of 14 unselected consecutive patients with total heart block and sinus rhythm. Pulmonary venous flow was assessed by transesophageal pulsed Doppler echocardiography in the VVI and DDD pacing modes. An inappropriate atrial timing caused a marked augmentation of the normally small pulmonary venous z wave in all patients ("negative atrial kick," peak z wave in DDD pacing 14.5 +/- 4.6 cm/s, VVI pacing 51.8 +/- 15.0 cm/s). Restoration of AV synchrony (DDD pacing, AV interval 100 ms) abolished these "cannon z waves" in all patients, and a normal pattern of pulmonary venous flow was achieved. Abnormal pulmonary venous flow characteristics were observed in 2 of 14 patients during DDD pacing with short AV intervals (100 ms). The Doppler pattern was similar to the findings seen in VVI pacing. Assessment of pulmonary venous flow by transesophageal pulsed Doppler echocardiography may provide a simple, sensitive, and relatively noninvasive technique to evaluate patients with suspected pacing induced adverse hemodynamics.

  10. Hemodynamic and adrenergic responses of bevantolol and propranolol in hypertensives.

    PubMed

    Snedden, W; Fernandez, P G; Vasdev, S; Bolli, P

    1989-01-01

    The hemodynamic and neurohumoral responses of 21 thiazide-resistant hypertensives receiving sequential chronic therapy with propranolol and bevantolol, a new cardioselective beta-1 blocker, were studied and compared with their responses to placebo. The objective was to determine to what extent decreased circulation levels of catecholamines and renin activity contributed to the hypotensive action of bevantolol and whether it demonstrated a significant sparing effect on vascular resistance. Both propranolol and bevantolol lowered supine and erect blood pressures to a comparable extent but the response of diastolic pressure to upright posture was maintained. Resting heart rates were lowered and postural tachycardia was attenuated. Propranolol induced a greater decrease in forearm blood flow and greater increase in vascular resistance than bevantolol. Both drug therapies were associated with lowered plasma concentrations of noradrenaline and adrenaline, while the decrease in noradrenaline levels was linearly related to the fall of mean arterial pressure for both drugs. Plasma renin activity was lowered only to a marginal extent by either drug but aldosterone concentrations were significantly reduced to a comparable extent by both drugs. The results suggest that a negative chronotropic action on the heart and an overall reduction in sympathetic nervous tone both contribute to the hypotensive effects of bevantolol and propranolol, but reduction of plasma renin activity may be of lesser importance. Bevantolol demonstrated a significant vascular sparing effect in this patient group compared with propranolol.

  11. A near-infrared spectroscopy computational model for cerebral hemodynamics.

    PubMed

    Kannan, R; Przekwas, A

    2012-11-01

    Near infrared spectroscopy (NIRS) is a technique used to detect and measure changes in the concentrations of oxygenated hemoglobin, deoxygenated hemoglobin, and water in tissues based on the differential absorption, scattering, and refraction of the near infrared light. In this imaging technique, the optical properties of tissues are reconstructed from the measurements obtained from the sensors located on the boundary. A computational method for the rapid noninvasive detection ∕ quantification of cerebral hemorrhage is described using the above procedure. CFD Research Corporation's finite volume computational biology code was used to numerically mimic the NIRS procedure by (i) noninvasively 'numerically penetrating' the brain tissues and (ii) reconstructing the optical properties the presence of water, oxygenated, and deoxygenated blood. These numerical noninvasive measurements are then used to predict the extent and severity of the brain hemorrhage. The paper also discusses ideas to obtain the location and the severity of a localized injury. Two-dimensional and three-dimensional simulations are performed as a proof of concept for the numerical formulation being feasible for the above mentioned detection/quantification. The results demonstrate that this numerical NIRS formulation can be used as a noninvasive technique for both qualitative and quantitative evaluation of cerebral hemodynamics.

  12. The Hemodynamics of Total Cavo-Pulmonary Connection Anatomies

    NASA Astrophysics Data System (ADS)

    Wang, Chang

    2005-11-01

    The single ventricle is a congenital heart defect in which the right side of the heart is hypoplastic or totally absent. This anomaly results in mixing of the oxygenated and deoxygenated blood in the single ventricle, reducing the amount of oxygen transferred to the body. In U.S. two in 1000 babies are born with a single ventricle heart defect. Palliative surgical treatments are performed in stages as the child grows. The last stage is the total cavo-pulmonary connection (TCPC), which bypasses the right side of the heart and the single ventricle drives blood throughout the pulmonary and systemic circulations. We simulate the flow in two TCPC anatomies using a sharp-interface, hybrid Cartesian/Immersed Boundary approach. The computed solutions are compared with PIV in-vitro experiments and analyzed in detail to elucidate the richness of the hemodynamics in the surgically create pouch region where the inferior and superior vena cava flows collide and bifurcate into the left and right pulmonary arteries. The effect of the connection anatomy on the flow dynamics will also be discussed.

  13. Ocular hemodynamic effects of nitrovasodilators in healthy subjects.

    PubMed

    Schmidl, D; Polska, E; Kiss, B; Sacu, S; Garhofer, G; Schmetterer, L

    2010-01-01

    Nitric oxide (NO) plays a key role in the regulation of ocular blood flow and may be an interesting therapeutic target in ocular ischemic disease. In the present study, we hypothesized that NO-releasing drugs may increase blood flow to the head of the optic nerve and also in the choroid. The study employed a randomized, placebo-controlled, double blind, four-way crossover design. On separate study days, 12 healthy subjects received infusions of nitroglycerin, isosorbide dinitrate, sodium nitroprusside, or placebo. All three study drugs reduced the mean arterial pressure (MAP) and ocular perfusion pressure (OPP) (P < 0.001). None of the administered drugs increased the ocular hemodynamic variables. By contrast, vascular resistance decreased dose dependently during administration of the study drugs (P < 0.001). These results indicate that systemic administration of NO-donor drugs is associated with a decrease in vascular resistance in the ocular vasculature. However, because these drugs also reduce blood pressure, they do not improve perfusion to the posterior eye pole.

  14. Bayesian estimation of the hemodynamic response function in functional MRI

    NASA Astrophysics Data System (ADS)

    Marrelec, G.; Benali, H.; Ciuciu, P.; Poline, J.-B.

    2002-05-01

    Functional MRI (fMRI) is a recent, non-invasive technique allowing for the evolution of brain processes to be dynamically followed in various cognitive or behavioral tasks. In BOLD fMRI, what is actually measured is only indirectly related to neuronal activity through a process that is still under investigation. A convenient way to analyze BOLD fMRI data consists of considering the whole brain as a system characterized by a transfer response function, called the Hemodynamic Response Function (HRF). Precise and robust estimation of the HRF has not been achieved yet: parametric methods tend to be robust but require too strong constraints on the shape of the HRF, whereas non-parametric models are not reliable since the problem is badly conditioned. We therefore propose a full Bayesian, non-parametric method that makes use of basic but relevant a priori knowledge about the underlying physiological process to make robust inference about the HRF. We show that this model is very robust to decreasing signal-to-noise ratio and to the actual noise sampling distribution. We finally apply the method to real data, revealing a wide variety of HRF shapes.

  15. Numerical predictions of hemodynamics following surgeries in cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Rayz, Vitaliy; Lawton, Michael; Boussel, Loic; Leach, Joseph; Acevedo, Gabriel; Halbach, Van; Saloner, David

    2014-11-01

    Large cerebral aneurysms present a danger of rupture or brain compression. In some cases, clinicians may attempt to change the pathological hemodynamics in order to inhibit disease progression. This can be achieved by changing the vascular geometry with an open surgery or by deploying a stent-like flow diverter device. Patient-specific CFD models can help evaluate treatment options by predicting flow regions that are likely to become occupied by thrombus (clot) following the procedure. In this study, alternative flow scenarios were modeled for several patients who underwent surgical treatment. Patient-specific geometries and flow boundary conditions were obtained from magnetic resonance angiography and velocimetry data. The Navier-Stokes equations were solved with a finite volume solver Fluent. A porous media approach was used to model flow-diverter devices. The advection-diffusion equation was solved in order to simulate contrast agent transport and the results were used to evaluate flow residence time changes. Thrombus layering was predicted in regions characterized by reduced velocities and shear stresses as well as increased flow residence time. The simulations indicated surgical options that could result in occlusion of vital arteries with thrombus. Numerical results were compared to experimental and clinical MRI data. The results demonstrate that image-based CFD models may help improve the outcome of surgeries in cerebral aneurysms. acknowledge R01HL115267.

  16. Advanced clinical monitoring: considerations for real-time hemodynamic diagnostics.

    PubMed

    Goldman, J M; Cordova, M J

    1994-01-01

    In an effort to ease staffing burdens and potentially improve patient outcome in an intensive care unit (ICU) environment, we are developing a real-time system to accurately and efficiently diagnose cardiopulmonary emergencies. The system is being designed to utilize all relevant routinely-monitored physiological data in order to automatically diagnose potentially fatal events. The initial stage of this project involved formulating the overall system design and appropriate methods for real-time data acquisition, data storage, data trending, waveform analysis, and implementing diagnostic rules. Initially, we defined a conceptual analysis of the minimum physiologic data set, and the monitoring time-frames (trends) which would be required to diagnose cardiopulmonary emergencies. Following that analysis, we used a fuzzy logic diagnostic engine to analyze physiological data during a simulated arrhythmic cardiac arrest (ACA) in order to assess the validity of our diagnostic methodology. We used rate, trend, and morphologic data extracted from the following signals: expired CO2 time-concentration curve (capnogram), electrocardiogram, and arterial blood pressure. The system performed well: The fuzzy logic engine effectively diagnosed the likelihood of ACA from the subtle hemodynamic trends which preceded the complete arrest. As the clinical picture worsened, the fuzzy logic-based system accurately indicated the change in patient condition. Termination of the simulated arrest was rapidly detected by the diagnostic engine. In view of the effectiveness of this fuzzy logic implementation, we plan to develop additional fuzzy logic modules to diagnose other cardiopulmonary emergencies.

  17. Hemodynamic Correlates of Proteinuria in Chronic Kidney Disease

    PubMed Central

    Townsend, Raymond R.; Fink, Jeffrey C.; Teal, Valerie; Anderson, Cheryl; Appel, Lawrence; Chen, Jing; He, Jiang; Litbarg, Natasha; Ojo, Akinlolu; Rahman, Mahboob; Rosen, Leigh; Sozio, Stephen M.; Steigerwalt, Susan; Strauss, Louise; Joffe, Marshall M.

    2011-01-01

    Summary Background and objectives Brachial artery measures of BP are associated with increasing degrees of proteinuria. Whether central measures of BP or vascular stiffness are associated with increased risk of proteinuria in patients with chronic kidney disease (CKD) is unknown. Design, setting, participants, & measurements Measurements of central and brachial artery BP, and aortic pulse wave velocity (PWV) were performed in a cross-sectional cohort of patients with CKD (n = 2144) from the Chronic Renal Insufficiency Cohort (CRIC) study to determine factors which predict increased risk of proteinuria. Multivariate analysis stratified by diabetes included age, ethnicity, gender, estimated glomerular filtration rate (GFR), waistline, smoking, heart rate, and medications to evaluate the relationship of hemodynamic factors and proteinuria. Results Brachial artery systolic BP (SBP) was important as an explanatory factor for variations in proteinuria among both diabetics (R2 = 0.40, P < 0.0001) and non diabetics (R2 = 0.38, P < 0.001). Measures of peripheral pulse pressure (PP), central SBP, and central pulse pressure added little to the explained variation in proteinuria beyond brachial artery SBP, whereas PWV as a measure of vascular stiffness incrementally accounted for a significant portion of variation in proteinuria beyond that explained by brachial artery SBP in diabetics (R2 = 0.42, P < 0.001) but not non diabetics. Conclusions Brachial artery SBP and PWV are both associated with variations in proteinuria in patients with CKD. PMID:21852669

  18. Clinical predictive factors of sildenafil response: a penile hemodynamic study.

    PubMed

    Elhanbly, S M; Elkholy, A A-M; Alghobary, M; Abou Al-Ghar, M

    2015-03-01

    Phosphodiestrase-5 inhibitors are an important line of treatment for erectile dysfunction (ED). To detect the clinical and hemodynamic predictors of sildenafil response, we conducted this study on 124 Egyptian men with ED. All patients were evaluated by thorough history and clinical assessment with measurement of the abridged international index of erectile function-5 (IIEF-5) score. All patients were then subjected to intracavernosal injection (ICI) of trimix and pharmaco-penile duplex ultrasonography (PPDU). Patients were then classified into sildenafil responders and non-responders after six consecutive doses of 100 mg sildenafil. On doing the binary logistic stepwise regression analysis, only ED duration, IIEF-5 score, and response to ICI were the significant independent predictors of sildenafil response. These three parameters together correctly predicted the sildenafil response by 81.5% (p value <0.001). With the receiver operator characteristic curve analysis, the cut-off value of ED duration was 2.5 years and it was 14 for the IIEF-5 score. These findings indicate that ED duration, the IIEF-5 score and response to ICI are more significant predictors of sildenafil response than the more expensive and time-consuming PPDU testing. PMID:25644869

  19. Deleterious effects of bretylium on hemodynamic recovery from ventricular fibrillation.

    PubMed

    Euler, D E; Zeman, T W; Wallock, M E; Scanlon, P J

    1986-07-01

    To study the effects of bretylium on the restoration of circulatory function after resuscitation from ventricular fibrillation, closed-chest anesthetized dogs were electrically fibrillated for 1 minute followed by defibrillation (direct-current shock). After one control episode of fibrillation and defibrillation, 16 dogs received a bolus of bretylium (10 mg/kg intravenously). A second episode of fibrillation and defibrillation was induced in eight dogs 3 minutes after bretylium and in eight dogs 4 hours after bretylium. Prior to bretylium, mean arterial blood pressure spontaneously recovered to exceed 200 mm Hg by 2 minutes after defibrillation in all 16 dogs. However, after bretylium, 13 of 16 dogs were in electromechanical dissociation 2 minutes after defibrillation (p less than 0.001). Despite external chest compression, epinephrine, and sodium bicarbonate, a stable blood pressure could not be restored in 6 of 16 dogs. Clofilium, a bretylium analogue lacking sympathetic influences, did not alter the pattern of hemodynamic recovery following defibrillation in five of five dogs. The results suggest that the effects of bretylium on the sympathetic nervous system may profoundly influence the outcome of cardiac resuscitation from fibrillation. PMID:3728284

  20. Right Ventricular Hemodynamics in Patients with Pulmonary Hypertension

    NASA Astrophysics Data System (ADS)

    Browning, James; Fenster, Brett; Hertzberg, Jean; Schroeder, Joyce

    2012-11-01

    Recent advances in cardiac magnetic resonance imaging (CMR) have allowed for characterization of blood flow in the right ventricle (RV), including calculation of vorticity and circulation, and qualitative visual assessment of coherent flow patterns. In this study, we investigate qualitative and quantitative differences in right ventricular hemodynamics between subjects with pulmonary hypertension (PH) and normal controls. Fifteen (15) PH subjects and 10 age-matched controls underwent same day 3D time resolved CMR and echocardiography. Echocardiography was used to determine right ventricular diastolic function as well as pulmonary artery systolic pressure (PASP). Velocity vectors, vorticity vectors, and streamlines in the RV were visualized in Paraview and total RV Early (E) and Atrial (A) wave diastolic vorticity was quantified. Visualizations of blood flow in the RV are presented for PH and normal subjects. The hypothesis that PH subjects exhibit different RV vorticity levels than normals during diastole is tested and the relationship between RV vorticity and PASP is explored. The mechanics of RV vortex formation are discussed within the context of pulmonary arterial pressure and right ventricular diastolic function coincident with PH.

  1. A parameter estimation framework for patient-specific hemodynamic computations

    NASA Astrophysics Data System (ADS)

    Itu, Lucian; Sharma, Puneet; Passerini, Tiziano; Kamen, Ali; Suciu, Constantin; Comaniciu, Dorin

    2015-01-01

    We propose a fully automated parameter estimation framework for performing patient-specific hemodynamic computations in arterial models. To determine the personalized values of the windkessel models, which are used as part of the geometrical multiscale circulation model, a parameter estimation problem is formulated. Clinical measurements of pressure and/or flow-rate are imposed as constraints to formulate a nonlinear system of equations, whose fixed point solution is sought. A key feature of the proposed method is a warm-start to the optimization procedure, with better initial solution for the nonlinear system of equations, to reduce the number of iterations needed for the calibration of the geometrical multiscale models. To achieve these goals, the initial solution, computed with a lumped parameter model, is adapted before solving the parameter estimation problem for the geometrical multiscale circulation model: the resistance and the compliance of the circulation model are estimated and compensated. The proposed framework is evaluated on a patient-specific aortic model, a full body arterial model, and multiple idealized anatomical models representing different arterial segments. For each case it leads to the best performance in terms of number of iterations required for the computational model to be in close agreement with the clinical measurements.

  2. Reading with Purpose

    ERIC Educational Resources Information Center

    Linderholm, Tracy

    2006-01-01

    In college-level courses, the vast majority of students read expository textbooks with a primary purpose in mind: to memorize and, hopefully, understand enough information to receive a particular grade on a course exam. Intuitively, this kind of reading is different than the kind of reading that these same students do when reading a novel while…

  3. Meaningful and Purposeful Practice

    ERIC Educational Resources Information Center

    Clementi, Donna

    2014-01-01

    This article describes a graphic, designed by Clementi and Terrill, the authors of "Keys to Planning for Learning" (2013), visually representing the components that contribute to meaningful and purposeful practice in learning a world language, practice that leads to greater proficiency. The entire graphic is centered around the letter…

  4. Spanish Special Purpose Dictionaries.

    ERIC Educational Resources Information Center

    Champion, James J.

    1982-01-01

    A variety of special purpose Spanish dictionaries available for students of Spanish are described, including dictionaries of groupings of associated words, technical language, regional and slang language, single authors' usage, historical periods, etymology, frequency, and reverse organization. Several illustrations of dictionary organization are…

  5. Purposes and Leadership.

    ERIC Educational Resources Information Center

    Gallin, Alice, Ed.

    1981-01-01

    Purposes and leadership in Catholic higher education are discussed to promote further dialogue among members of the Association of Catholic Colleges and Universities on institutional roots, present institutional conditions, and future vision. Papers and authors include: Commentary on Bishops' Pastoral Letter on Catholic Higher Education (William…

  6. Acute effect of nitric oxide supplement on blood nitrate/nitrite and hemodynamic variables in resistance trained men.

    PubMed

    Bloomer, Richard J; Williams, Sara A; Canale, Robert E; Farney, Tyler M; Kabir, Mohammad M

    2010-10-01

    Nitric oxide dietary supplements are extremely popular within the sport and bodybuilding community. Most products contain l-arginine, for which there is no direct evidence that oral L-arginine increases circulating nitric oxide or blood flow. A new molecule (2-[nitrooxy]thyl 2-amino-3-methylbutanoate) is being marketed as a sport supplement for purposes of delivering "real nitric oxide" to the circulation. In the present study, we measured the acute effects of this supplement on blood nitrate/nitrite and hemodynamic variables. Ten resistance trained men (26 ± 4 years old; 8 ± 6 years of resistance exercise training) reported to the laboratory in random order after a 10-hour overnight fast on 2 occasions separated by 1 week and were provided the supplement (2-[nitrooxy]ethyl 2-amino-3-methylbutanoate) or placebo. Heart rate and blood pressure were recorded, and venous blood samples were collected before and at 5, 15, 30, and 60 minutes after complete breakdown of the supplement (5 minutes post intake) or placebo. Blood samples were assayed for plasma nitrate/nitrite. No interaction (p = 0.99), condition (p = 0.18), or time (p = 0.98) effects were noted for plasma nitrate/nitrite, with values remaining nearly identical across time for placebo (∼27 μmol·L(-1)) and increasing a maximum of ∼6.7% (from 32.9 to 35.1 μmol·L(-1)) at the 15-minute collection period for the supplement. In regards to hemodynamic variables, no interaction, condition, or time effects were noted for heart rate, systolic, or diastolic blood pressure (p > 0.05), with values near identical between conditions and virtually unchanged across time. These findings indicate that 2-(nitrooxy)ethyl 2-amino-3-methylbutanoate has a small effect on increasing circulating nitrate/nitrite and does not cause any change in hemodynamic variables within the 1 hour postingestion period in a sample of resistance trained men.

  7. Age-correlated changes in cerebral hemodynamics assessed by near-infrared spectroscopy.

    PubMed

    Safonova, Larisa P; Michalos, Antonios; Wolf, Ursula; Wolf, Martin; Hueber, Dennis M; Choi, Jee H; Gupta, Rajarsi; Polzonetti, Chiara; Mantulin, William W; Gratton, Enrico

    2004-01-01

    Cerebral hemodynamic responses due to normal aging may interfere with hormonal changes, drug therapy, diseases, life style, and other factors. Age-correlated alterations in cerebral vasculature and autoregulatory mechanisms are the subject of interest in many studies. Near-infrared spectroscopy (NIRS) is widely used for monitoring cerebral hemodynamics and oxygenation changes at the level of small vessels. We believe that the compensatory ability of cerebral arterioles under hypoxic conditions and the dilatatory ability of cerebral vessels due to vasomotion may decline with normal aging. To test this hypothesis we used frequency-domain NIRS to measure changes in cerebral tissue oxygenation and oxy- and deoxy-hemoglobin concentrations caused by hypoxia during breath holding. We also assessed cerebral vasomotion during profound relaxation. Thirty seven healthy volunteers, 12 females and 25 males, ranging from 22 to 56 years of age (mean age 35 +/- 11 years) participated in the study. We observed age-correlated changes in the cerebral hemodynamics of normal subjects: diminished cerebral hemodynamic response to hypoxia due to breath holding in middle-aged subjects (38-56 years) and reduced amplitude of cerebral hemodynamic changes due to vasomotion during rest. Snoring related changes in cerebral hemodynamics did not allow us to observe the effect of age in a group of snorers. The prolonged supine position influenced measured changes due to hypoxia. In this investigation NIRS methodology allowed detection of age-correlated changes in cerebral oxygenation and hemodynamics. Other variables, such as snoring or posture impacted the observations in our group of healthy volunteers. PMID:15381340

  8. Purposive discovery of operations

    NASA Technical Reports Server (NTRS)

    Sims, Michael H.; Bresina, John L.

    1992-01-01

    The Generate, Prune & Prove (GPP) methodology for discovering definitions of mathematical operators is introduced. GPP is a task within the IL exploration discovery system. We developed GPP for use in the discovery of mathematical operators with a wider class of representations than was possible with the previous methods by Lenat and by Shen. GPP utilizes the purpose for which an operator is created to prune the possible definitions. The relevant search spaces are immense and there exists insufficient information for a complete evaluation of the purpose constraint, so it is necessary to perform a partial evaluation of the purpose (i.e., pruning) constraint. The constraint is first transformed so that it is operational with respect to the partial information, and then it is applied to examples in order to test the generated candidates for an operator's definition. In the GPP process, once a candidate definition survives this empirical prune, it is passed on to a theorem prover for formal verification. We describe the application of this methodology to the (re)discovery of the definition of multiplication for Conway numbers, a discovery which is difficult for human mathematicians. We successfully model this discovery process utilizing information which was reasonably available at the time of Conway's original discovery. As part of this discovery process, we reduce the size of the search space from a computationally intractable size to 3468 elements.

  9. In vivo isolation of the effects of melanin from underlying hemodynamics across skin types using spatial frequency domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Saager, Rolf B.; Sharif, Ata; Kelly, Kristen M.; Durkin, Anthony J.

    2016-05-01

    Skin is a highly structured tissue, raising concerns as to whether skin pigmentation due to epidermal melanin may confound accurate measurements of underlying hemodynamics. Using both venous and arterial cuff occlusions as a means of inducing differential hemodynamic perturbations, we present analyses of spectra limited to the visible or near-infrared regime, in addition to a layered model approach. The influence of melanin, spanning Fitzpatrick skin types I to V, on underlying estimations of hemodynamics in skin as interpreted by these spectral regions are assessed. The layered model provides minimal cross-talk between melanin and hemodynamics and enables removal of problematic correlations between measured tissue oxygenation estimates and skin phototype.

  10. [Data processing system for laboratory and hemodynamic heart catheterization measurements].

    PubMed

    Jensch, P; Meyer, J; Mattar, E; Ameling, W; Effert, S

    1976-10-01

    In cooperation with the Department of Electronic Data Processing Systems we have developed a data processing unit for the analysis of hemodynamic data at the Department of Internal Medicine I. The aim was to design a computer-system for the daily routine in heart-catheterizations as well as for the solution of scientific problems during hemodynamic studies. In the on-line-mode besides the ECG up to four pressures can be analysed simultaneously. Analog and digital tapes can also be processed off-line on demand. The concept of the whole system and the individual steps of computer-handling are adjusted to the problems of data-analysis in praxis from the viewpoint of the examining cardiologist. Since the system is interactive after each measurement and each given command the computer-results are displayed on the video-scope. Because of the modular structure of the program new medical criteria can easily be implemented at any time. Since the computer-system is not effectively used with only one cath-lab other units possibly of different hard-ware configuration can be connected simultaneously to the computer. Each cath-lab shares 16 K out of the total 32 K core-memory. The results are displayed graphically and alpha-numerically on video-scope, x-y-plotter and line printer. The sampling-rate for fluid-filled catheters is 200 Hz and for catheter-tip-manometers 400 Hz. Smothing and differentiation-procedures are adapted to the respective catheter-material. The computer-program calibrates the different pressure amplifiers automatically. After defining the catheter-position the pressure-signals are sampled for 10 s and immediately afterwards analyzed by the computer. The ECG and the corresponding pressure-curves are displayed on the video-scope. The automatically selected representative beat as well as each of the identified and numerated other beats of the sampling-phase can be displayed selectively together with its numerical results. The computer marks the positions within

  11. Can maternal-fetal hemodynamics influence prenatal development in dogs?

    PubMed

    Freitas, Luana Azevedo de; Mota, Gustavo Lobato; Silva, Herlon Victor Rodrigues; Carvalho, Cibele Figueira; Silva, Lúcia Daniel Machado da

    2016-09-01

    The goals of this study were to report embryonic and fetal ultrasound changes and compare blood flow of uteroplacental and umbilical arteries of normal and abnormal conceptus. Accordingly, from the day of mating or artificial insemination, all fetuses in 60 pregnancies were evaluated weekly. According to the ultrasound findings, the gestational age was determined and the conceptuses were divided into normal or abnormal (embryonic and fetal abnormalities). The two-dimensional ultrasound assessment consists of measuring and evaluating the echogenicity of conceptus and extra-fetal structures. Doppler velocimetry measured the resistivity index (RI) and pulsatility index (PI) of uteroplacental and umbilical arteries. Two-dimensional and Doppler measurements were expressed as mean and standard deviation. Differences between normal and abnormal groups were subject to Mann-Whitney test (P<0.05). Of 264 fetuses, 15.90% showed embryonic abnormalities (resorption) and 5.68% presented fetal abnormalities (congenital abnormalities, fetal underdevelopment and fetal death). We observed a reduced diameter and abnormalities in the contour of gestational vesicle, lack of viability, increased placental thickness, increased fluid echogenicity and increases in RI and PI of uteroplacental arteries of conceptuses with embryonic resorption between the 2nd and 4th weeks. Fetuses with abnormalities showed changes in the flow of uteroplacental and umbilical arteries prior to visualization of two-dimensional alterations and different vascular behavior according to the classification of the change. Results show that ultrasound is efficient for the detection of embryonic and fetal abnormalities. When combined with Doppler ultrasound, it allows early detection of gestational changes, as well as hemodynamic changes, in conceptuses with abnormalities, which may influence their development. PMID:27509872

  12. Requirements for mesh resolution in 3D computational hemodynamics.

    PubMed

    Prakash, S; Ethier, C R

    2001-04-01

    Computational techniques are widely used for studying large artery hemodynamics. Current trends favor analyzing flow in more anatomically realistic arteries. A significant obstacle to such analyses is generation of computational meshes that accurately resolve both the complex geometry and the physiologically relevant flow features. Here we examine, for a single arterial geometry, how velocity and wall shear stress patterns depend on mesh characteristics. A well-validated Navier-Stokes solver was used to simulate flow in an anatomically realistic human right coronary artery (RCA) using unstructured high-order tetrahedral finite element meshes. Velocities, wall shear stresses (WSS), and wall shear stress gradients were computed on a conventional "high-resolution" mesh series (60,000 to 160,000 velocity nodes) generated with a commercial meshing package. Similar calculations were then performed in a series of meshes generated through an adaptive mesh refinement (AMR) methodology. Mesh-independent velocity fields were not very difficult to obtain for both the conventional and adaptive mesh series. However, wall shear stress fields, and, in particular, wall shear stress gradient fields, were much more difficult to accurately resolve. The conventional (nonadaptive) mesh series did not show a consistent trend towards mesh-independence of WSS results. For the adaptive series, it required approximately 190,000 velocity nodes to reach an r.m.s. error in normalized WSS of less than 10 percent. Achieving mesh-independence in computed WSS fields requires a surprisingly large number of nodes, and is best approached through a systematic solution-adaptive mesh refinement technique. Calculations of WSS, and particularly WSS gradients, show appreciable errors even on meshes that appear to produce mesh-independent velocity fields.

  13. Gender affects sympathetic and hemodynamic response to postural stress

    NASA Technical Reports Server (NTRS)

    Shoemaker, J. K.; Hogeman, C. S.; Khan, M.; Kimmerly, D. S.; Sinoway, L. I.

    2001-01-01

    We tested the hypothesis that differences in sympathetic reflex responses to head-up tilt (HUT) between males (n = 9) and females (n = 8) were associated with decrements in postural vasomotor responses in women. Muscle sympathetic nerve activity (MSNA; microneurography), heart rate, stroke volume (SV; Doppler), and blood pressure (Finapres) were measured during a progressive HUT protocol (5 min at each of supine, 20 degrees, 40 degrees, and 60 degrees ). MSNA and hemodynamic responses were also measured during the cold pressor test (CPT) to examine nonbaroreflex neurovascular control. SV was normalized to body surface area (SV(i)) to calculate the index of cardiac output (Q(i)), and total peripheral resistance (TPR). During HUT, heart rate increased more in females versus males (P < 0.001) and SV(i) and Q(i) decreased similarly in both groups. Mean arterial pressure (MAP) increased to a lesser extent in females versus males in the HUT (P < 0.01) but increases in TPR during HUT were similar. MSNA burst frequency was lower in females versus males in supine (P < 0.03) but increased similarly during HUT. Average amplitude/burst increased in 60 degrees HUT for males but not females. Both males and females demonstrated an increase in MAP as well as MSNA burst frequency, mean burst amplitude, and total MSNA during the CPT. However, compared with females, males demonstrated a greater neural response (DeltaTotal MSNA) due to a larger increase in mean burst amplitude (P < 0.05). Therefore, these data point to gender-specific autonomic responses to cardiovascular stress. The different MSNA response to postural stress between genders may contribute importantly to decrements in blood pressure control during HUT in females.

  14. A dimensionless parameter for classifying hemodynamics in intracranial

    NASA Astrophysics Data System (ADS)

    Asgharzadeh, Hafez; Borazjani, Iman

    2015-11-01

    Rupture of an intracranial aneurysm (IA) is a disease with high rates of mortality. Given the risk associated with the aneurysm surgery, quantifying the likelihood of aneurysm rupture is essential. There are many risk factors that could be implicated in the rupture of an aneurysm. However, the most important factors correlated to the IA rupture are hemodynamic factors such as wall shear stress (WSS) and oscillatory shear index (OSI) which are affected by the IA flows. Here, we carry out three-dimensional high resolution simulations on representative IA models with simple geometries to test a dimensionless number (first proposed by Le et al., ASME J Biomech Eng, 2010), denoted as An number, to classify the flow mode. An number is defined as the ratio of the time takes the parent artery flow transports across the IA neck to the time required for vortex ring formation. Based on the definition, the flow mode is vortex if An>1 and it is cavity if An<1. We show that the specific definition of Le et al. works for sidewall but needs to be modified for bifurcation aneurysms. In addition, we show that this classification works on three-dimensional geometries reconstructed from three-dimensional rotational angiography of human subjects. Furthermore, we verify the correlation of IA flow mode and WSS/OSI on the human subject IA. This work was supported partly by the NIH grant R03EB014860, and the computational resources were partly provided by CCR at UB. We thank Prof. Hui Meng and Dr. Jianping Xiang for providing us the database of aneurysms and helpful discussions.

  15. Pulmonary hemodynamic profile in chronic obstructive pulmonary disease

    PubMed Central

    Portillo, Karina; Torralba, Yolanda; Blanco, Isabel; Burgos, Felip; Rodriguez-Roisin, Roberto; Rios, Jose; Roca, Josep; Barberà, Joan A

    2015-01-01

    Introduction Few data are available in regards to the prevalence of pulmonary hypertension (PH) in the broad spectrum of COPD. This study was aimed at assessing the prevalence of PH in a cohort of COPD patients across the severity of airflow limitation, and reporting the hemodynamic characteristics at rest and during exercise. Methods We performed a retrospective analysis on COPD patients who underwent right-heart catheterization in our center with measurements obtained at rest (n=139) and during exercise (n=85). PH was defined as mean pulmonary artery pressure (mPAP) ≥25 mmHg and pulmonary capillary wedge pressure <15 mmHg. Exercise-induced PH (EIPH) was defined by a ratio of ΔmPAP/Δcardiac output >3. Results PH was present in 25 patients (18%). According to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification, PH prevalence in GOLD 2 was 7% (3 patients); 25% (14 patients) in GOLD 3; and 22% (8 patients) in GOLD 4. Severe PH (mPAP ≥35 mmHg) was identified in four patients (2.8%). Arterial partial oxygen pressure was the outcome most strongly associated with PH (r=−0.29, P<0.001). EIPH was observed in 60 patients (71%) and had a similar prevalence in both GOLD 2 and 3, and was present in all GOLD 4 patients. Patients with PH had lower cardiac index during exercise than patients without PH (5.0±1.2 versus 6.7±1.4 L/min/m2, respectively; P=0.001). Conclusion PH has a similar prevalence in COPD patients with severe and very-severe airflow limitation, being associated with the presence of arterial hypoxemia. In contrast, EIPH is highly prevalent, even in moderate COPD, and might contribute to limiting exercise tolerance. PMID:26203238

  16. FALLS-protocol: lung ultrasound in hemodynamic assessment of shock.

    PubMed

    Lichtenstein, D

    2013-01-01

    The assessment of acute circulatory failure is a challenge in absence of solid gold standard. It is suggested that artifacts generated by lung ultrasound can be of help. The FALLS-protocol (Fluid Administration Limited by Lung Sonography) follows Weil's classification of shocks. Firstly, it searches for pericardial fluid, then right heart enlargment, lastly abolished lung sliding. In this setting, the diagnoses of pericardial tamponade, pulmonary embolism and tension pneumothorax, i.e. obstructive shock, can be schematically ruled out. Moreover, the search of diffuse lung rockets (i.e. multiple B-lines, a comet-tail artifact) is performed. Its absence excludes pulmonary edema, that in clinical practice is left cardiogenic shock (most cases). At this step, the patient (defined FALLS-responder) receives fluid therapy. He/she has usually a normal sonographic lung surface, an A-profile. Any clinical improvement suggests hypovolemic shock. The absence of improvement generates continuation of fluid therapy, eventually yielding fluid overload. This condition results in the change from A-profile to B-profile. Lung ultrasound has the advantage to demonstrate this interstitial syndrome at an early and infraclinical stage (FALLS-endpoint). The change from horizontal A-lines to vertical B-lines can be considered as a direct marker of volemia in this use. By elimination, this change indicates schematically distributive shock, while in current practice septic shock. The major limitation is the B-profile on admission generated by an initial lung disorder. FALLS-protocol, which can be associated with no drawback with traditional hemodynamic tools, uses a simple machine (without Doppler) and a suitable microconvex probe allowing for heart, lung and vein assessment. PMID:24364005

  17. Gender affects sympathetic and hemodynamic response to postural stress.

    PubMed

    Shoemaker, J K; Hogeman, C S; Khan, M; Kimmerly, D S; Sinoway, L I

    2001-11-01

    We tested the hypothesis that differences in sympathetic reflex responses to head-up tilt (HUT) between males (n = 9) and females (n = 8) were associated with decrements in postural vasomotor responses in women. Muscle sympathetic nerve activity (MSNA; microneurography), heart rate, stroke volume (SV; Doppler), and blood pressure (Finapres) were measured during a progressive HUT protocol (5 min at each of supine, 20 degrees, 40 degrees, and 60 degrees ). MSNA and hemodynamic responses were also measured during the cold pressor test (CPT) to examine nonbaroreflex neurovascular control. SV was normalized to body surface area (SV(i)) to calculate the index of cardiac output (Q(i)), and total peripheral resistance (TPR). During HUT, heart rate increased more in females versus males (P < 0.001) and SV(i) and Q(i) decreased similarly in both groups. Mean arterial pressure (MAP) increased to a lesser extent in females versus males in the HUT (P < 0.01) but increases in TPR during HUT were similar. MSNA burst frequency was lower in females versus males in supine (P < 0.03) but increased similarly during HUT. Average amplitude/burst increased in 60 degrees HUT for males but not females. Both males and females demonstrated an increase in MAP as well as MSNA burst frequency, mean burst amplitude, and total MSNA during the CPT. However, compared with females, males demonstrated a greater neural response (DeltaTotal MSNA) due to a larger increase in mean burst amplitude (P < 0.05). Therefore, these data point to gender-specific autonomic responses to cardiovascular stress. The different MSNA response to postural stress between genders may contribute importantly to decrements in blood pressure control during HUT in females. PMID:11668064

  18. Hemodynamics in the Circle of Willis with Internal Carotid Artery Stenosis under Cervical Rotatory Manipulation: A Finite Element Analysis

    PubMed Central

    Lin, Weishen; Ma, Xiaokang; Deng, Datai; Li, Yikai

    2015-01-01

    Background The circle of Willis (CoW) plays an important role in cerebral collateral circulation. The hemodynamics changes in the CoW have usually been associated with the internal carotid artery (ICA) stenosis, but whether rotatory manipulation will affect it remains unknown. Material/Methods In this study we attempted to analyze the influence of rotatory manipulation on the hemodynamics in the CoW in models with or without ICA stenosis by means of finite element analysis. For this purpose, the CoW was reasonably simplified and a fluid-solid coupling 3D finite element model was created by using MIMICS10.0 and ANSYS14.5. The healthy (without stenosis) and the diseased (ratios of stenosis include 15%, 30%, 45%, 60%, 70%, 80%, and 90%) situations were simulated. A remote displacement of 60° was applied at a distal ICA (the right ICA was chosen here) to imitate the rotatory manipulation. Blood flow was then monitored at the anterior communicating artery (ACoA) and posterior communicating arteries (PCoA). Results Before the conduction of rotatory manipulation, blood flow changed significantly only when the stenosis ratio was increased to more than 70%, and the situation did not have significant difference after the application of remote displacement except the model with stenosis ration of 90%. Conclusions The result suggests that the rotatory manipulation does not have an obvious influence on the blood flow in the CoW when the stenosis of ICA is less than 90%, and this kind of manipulation is suggested to be a safe technique in most of the clinical applications. PMID:26103051

  19. Bend sweep angle and Reynolds number effects on hemodynamics of s-shaped arteries.

    PubMed

    Niazmand, H; Rajabi Jaghargh, E

    2010-09-01

    The purpose of this study is to investigate the effects of the Reynolds number and the bend sweep angle on the blood flow patterns of S-shaped bends. The numerical simulations of steady flows in S-shaped bends with sweep angles of 45 degrees , 90 degrees , and 135 degrees are performed at Reynolds numbers of 125, 500, and 960. Hemodynamic characteristics such as secondary flows, vorticity, and axial velocity profiles are analyzed in detail. Flow patterns in S-shaped bends are strongly dependent on both Reynolds number and bend sweep angle, which can be categorized into three groups based on the first bend secondary flow effects on the transverse flow of the second bend. For low Reynolds numbers and any sweep angles, secondary flows in the second bend eliminate the first bend effects in the early sections of the second bend and therefore the axial velocity profile is consistent with the bend curvature, while for high Reynolds numbers depending on the bend sweep angles the secondary vortex pattern of the first bend may persist partially or totally throughout the second bend leading to a four-vortex secondary structure. Moreover, an interesting flow feature observed at the Reynolds number of 960 is that the secondary flow asymmetrical behavior occurred around the second bend exit and along the outflow straight section. This symmetry-breaking phenomenon which has not been reported in the previous studies is shown to be more pronounced in the 90 degrees S-shaped bend as compared to other models considered here. The probability of flow separation as one of the important flow features contributing to the onset and development of arterial wall diseases is also studied. It is observed that the second bend outer wall of gentle bends with sweep angles from 20 degrees to 30 degrees at high enough Reynolds numbers are prone to flow separation.

  20. Hemodynamic Response to Interictal Epileptiform Discharges Addressed by Personalized EEG-fNIRS Recordings

    PubMed Central

    Pellegrino, Giovanni; Machado, Alexis; von Ellenrieder, Nicolas; Watanabe, Satsuki; Hall, Jeffery A.; Lina, Jean-Marc; Kobayashi, Eliane; Grova, Christophe

    2016-01-01

    Objective: We aimed at studying the hemodynamic response (HR) to Interictal Epileptic Discharges (IEDs) using patient-specific and prolonged simultaneous ElectroEncephaloGraphy (EEG) and functional Near InfraRed Spectroscopy (fNIRS) recordings. Methods: The epileptic generator was localized using Magnetoencephalography source imaging. fNIRS montage was tailored for each patient, using an algorithm to optimize the sensitivity to the epileptic generator. Optodes were glued using collodion to achieve prolonged acquisition with high quality signal. fNIRS data analysis was handled with no a priori constraint on HR time course, averaging fNIRS signals to similar IEDs. Cluster-permutation analysis was performed on 3D reconstructed fNIRS data to identify significant spatio-temporal HR clusters. Standard (GLM with fixed HRF) and cluster-permutation EEG-fMRI analyses were performed for comparison purposes. Results: fNIRS detected HR to IEDs for 8/9 patients. It mainly consisted oxy-hemoglobin increases (seven patients), followed by oxy-hemoglobin decreases (six patients). HR was lateralized in six patients and lasted from 8.5 to 30 s. Standard EEG-fMRI analysis detected an HR in 4/9 patients (4/9 without enough IEDs, 1/9 unreliable result). The cluster-permutation EEG-fMRI analysis restricted to the region investigated by fNIRS showed additional strong and non-canonical BOLD responses starting earlier than the IEDs and lasting up to 30 s. Conclusions: (i) EEG-fNIRS is suitable to detect the HR to IEDs and can outperform EEG-fMRI because of prolonged recordings and greater chance to detect IEDs; (ii) cluster-permutation analysis unveils additional HR features underestimated when imposing a canonical HR function (iii) the HR is often bilateral and lasts up to 30 s. PMID:27047325

  1. Intraoperative brain hemodynamic response assessment with real-time hyperspectral optical imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Laurence, Audrey; Pichette, Julien; Angulo-Rodríguez, Leticia M.; Saint Pierre, Catherine; Lesage, Frédéric; Bouthillier, Alain; Nguyen, Dang Khoa; Leblond, Frédéric

    2016-03-01

    Following normal neuronal activity, there is an increase in cerebral blood flow and cerebral blood volume to provide oxygenated hemoglobin to active neurons. For abnormal activity such as epileptiform discharges, this hemodynamic response may be inadequate to meet the high metabolic demands. To verify this hypothesis, we developed a novel hyperspectral imaging system able to monitor real-time cortical hemodynamic changes during brain surgery. The imaging system is directly integrated into a surgical microscope, using the white-light source for illumination. A snapshot hyperspectral camera is used for detection (4x4 mosaic filter array detecting 16 wavelengths simultaneously). We present calibration experiments where phantoms made of intralipid and food dyes were imaged. Relative concentrations of three dyes were recovered at a video rate of 30 frames per second. We also present hyperspectral recordings during brain surgery of epileptic patients with concurrent electrocorticography recordings. Relative concentration maps of oxygenated and deoxygenated hemoglobin were extracted from the data, allowing real-time studies of hemodynamic changes with a good spatial resolution. Finally, we present preliminary results on phantoms obtained with an integrated spatial frequency domain imaging system to recover tissue optical properties. This additional module, used together with the hyperspectral imaging system, will allow quantification of hemoglobin concentrations maps. Our hyperspectral imaging system offers a new tool to analyze hemodynamic changes, especially in the case of epileptiform discharges. It also offers an opportunity to study brain connectivity by analyzing correlations between hemodynamic responses of different tissue regions.

  2. Saturation thresholds of evoked neural and hemodynamic responses in awake and asleep rats

    NASA Astrophysics Data System (ADS)

    Schei, Jennifer L.; Van Nortwick, Amy S.; Meighan, Peter C.; Rector, David M.

    2011-03-01

    Neural activation generates a hemodynamic response to the localized region replenishing nutrients to the area. Changes in vigilance state have been shown to alter the vascular response where the vascular response is muted during wake compared to quiet sleep. We tested the saturation thresholds of the neurovascular response in the auditory cortex during wake and sleep by chronically implanting rats with an EEG electrode, a light emitting diode (LED, 600 nm), and photodiode to simultaneously measure evoked response potentials (ERPs) and evoked hemodynamic responses. We stimulated the cortex with a single speaker click delivered at random intervals 2-13 s at varied stimulus intensities ranging from 45-80 dB. To further test the potential for activity related saturation, we sleep deprived animals for 2, 4, or 6 hours and recorded evoked responses during the first hour recovery period. With increasing stimulus intensity, integrated ERPs and evoked hemodynamic responses increased; however the hemodynamic response approached saturation limits at a lower stimulus intensity than the ERP. With longer periods of sleep deprivation, the integrated ERPs did not change but evoked hemodynamic responses decreased. There may be physical limits in cortical blood delivery and vascular compliance, and with extended periods of neural activity during wake, vessels may approach these limits.

  3. Depth-resolved optical imaging of hemodynamic response in mouse brain with microcirculatory beds

    NASA Astrophysics Data System (ADS)

    Jia, Yali; Nettleton, Rosemary; Rosenberg, Mara; Boudreau, Eilis; Wang, Ruikang K.

    2011-03-01

    Optical hemodynamic imaging employed in pre-clinical studies with high spatial and temporal resolution is significant to unveil the functional activities of brain and the mechanism of internal or external stimulus effects in diverse pathological conditions and treatments. Most current optical systems only resolve hemodynamic changes within superficial macrocirculatory beds, such as laser speckle contrast imaging; or only provide vascular structural information within microcirculatory beds, such as multi-photon microscopy. In this study, we introduce a hemodynamic imaging system based on Optical Micro-angiography (OMAG) which is capable of resolving and quantifying 3D dynamic blood perfusion down to microcirculatory level. This system can measure the optical phase shifts caused by moving blood cells in microcirculation. Here, the utility of OMAG was demonstrated by monitoring the hemodynamic response to alcohol administration in mouse prefrontal cortex. Our preliminary results suggest that the spatiotemporal tracking of cerebral micro-hemodynamic using OMAG can be successfully applied to the mouse brain and reliably distinguish between vehicle and alcohol stimulation experiment.

  4. Self-reported tolerance influences prefrontal cortex hemodynamics and affective responses.

    PubMed

    Tempest, Gavin; Parfitt, Gaynor

    2016-02-01

    The relationship between cognitive and sensory processes in the brain contributes to the regulation of affective responses (pleasure-displeasure). Exercise can be used to manipulate sensory processes (by increasing physiological demand) in order to examine the role of dispositional traits that may influence an individual's ability to cognitively regulate these responses. With the use of near infrared spectroscopy, in this study we examined the influence of self-reported tolerance upon prefrontal cortex (PFC) hemodynamics and affective responses. The hemodynamic response was measured in individuals with high or low tolerance during an incremental exercise test. Sensory manipulation was standardized against metabolic processes (ventilatory threshold [VT] and respiratory compensation point [RCP]), and affective responses were recorded. The results showed that the high-tolerance group displayed a larger hemodynamic response within the right PFC above VT (which increased above RCP). The low-tolerance group showed a larger hemodynamic response within the left PFC above VT. The high-tolerance group reported a more positive/less negative affective response above VT. These findings provide direct neurophysiological evidence of differential hemodynamic responses within the PFC that are associated with tolerance in the presence of increased physiological demands. This study supports the role of dispositional traits and previous theorizing into the underlying mechanisms (cognitive vs. sensory processes) of affective responses. PMID:26337703

  5. Mayer waves reduce the accuracy of estimated hemodynamic response functions in functional near-infrared spectroscopy

    PubMed Central

    Yücel, Meryem A.; Selb, Juliette; Aasted, Christopher M.; Lin, Pei-Yi; Borsook, David; Becerra, Lino; Boas, David A.

    2016-01-01

    Analysis of cerebral hemodynamics reveals a wide spectrum of oscillations ranging from 0.0095 to 2 Hz. While most of these oscillations can be filtered out during analysis of functional near-infrared spectroscopy (fNIRS) signals when estimating stimulus evoked hemodynamic responses, oscillations around 0.1 Hz are an exception. This is due to the fact that they share a common spectral range with typical stimulus evoked hemodynamic responses from the brain. Here we investigate the effect of hemodynamic oscillations around 0.1 Hz on the estimation of hemodynamic response functions from fNIRS data. Our results show that for an expected response of ~1 µM in oxygenated hemoglobin concentration (HbO), Mayer wave oscillations with an amplitude > ~1 µM at 0.1 Hz reduce the accuracy of the estimated response as quantified by a 3 fold increase in the mean squared error and decrease in correlation (R2 below 0.78) when compared to the true HRF. These results indicate that the amplitude of oscillations at 0.1 Hz can serve as an objective metric of the expected HRF estimation accuracy. In addition, we investigated the effect of short separation regression on the recovered HRF, and found that this improves the recovered HRF when large amplitude 0.1 Hz oscillations are present in fNIRS data. We suspect that the development of other filtering strategies may provide even further improvement. PMID:27570699

  6. [MONITORING OF HEMODYNAMICS IN THE CHOICE OF INTENSIVE THERAPY IN THE OPERATED INFANTS].

    PubMed

    Stepanenko, S M; Afukov, I I; Sitnikova, M I

    2016-01-01

    Noninvasive monitoring in obtaining important and reliable information relevant to pediatric practices, not only in respect of dangers and complications of most invasive techniques, but also because a number of them difficult or even impossible in infants. The aim of this study was to estimate the significance of hemodynamic parameters and capabilities of ECHO and dophlercardiography for analyzing violations hemodynamics in primary diagnosis and conduct drug therapy in infants. The study included the results of a survey of 65 infants aged from 29 to 39 weeks with various surgical pathology, who received the various options the hemodynamic support. In the initial assessment and selecting tactics of therapy for hemodynamic analysis carried out routine monitoring and for evaluation of cardiac contractility used echo- and Doppler exams. All children have pointed out a number of significant changes of haemodynamics, that has required inotropic therapy with dopamine (64% of children with diaphragmatic hernia received additional dobutamine). Validation of expressed pulmonary hypertension children appointed sildenafil, and in the absence ofthe effect used nitrous oxide. Hemodynamic monitoring allows to monitor the status of circulation on the background of the treatment and to make timely changes to the script therapy. PMID:27192852

  7. Mayer waves reduce the accuracy of estimated hemodynamic response functions in functional near-infrared spectroscopy.

    PubMed

    Yücel, Meryem A; Selb, Juliette; Aasted, Christopher M; Lin, Pei-Yi; Borsook, David; Becerra, Lino; Boas, David A

    2016-08-01

    Analysis of cerebral hemodynamics reveals a wide spectrum of oscillations ranging from 0.0095 to 2 Hz. While most of these oscillations can be filtered out during analysis of functional near-infrared spectroscopy (fNIRS) signals when estimating stimulus evoked hemodynamic responses, oscillations around 0.1 Hz are an exception. This is due to the fact that they share a common spectral range with typical stimulus evoked hemodynamic responses from the brain. Here we investigate the effect of hemodynamic oscillations around 0.1 Hz on the estimation of hemodynamic response functions from fNIRS data. Our results show that for an expected response of ~1 µM in oxygenated hemoglobin concentration (HbO), Mayer wave oscillations with an amplitude > ~1 µM at 0.1 Hz reduce the accuracy of the estimated response as quantified by a 3 fold increase in the mean squared error and decrease in correlation (R(2) below 0.78) when compared to the true HRF. These results indicate that the amplitude of oscillations at 0.1 Hz can serve as an objective metric of the expected HRF estimation accuracy. In addition, we investigated the effect of short separation regression on the recovered HRF, and found that this improves the recovered HRF when large amplitude 0.1 Hz oscillations are present in fNIRS data. We suspect that the development of other filtering strategies may provide even further improvement. PMID:27570699

  8. The hemodynamic effects of ibopamine, a dopamine congener, in patients with congestive heart failure.

    PubMed

    Leier, C V; Ren, J H; Huss, P; Unverferth, D V

    1986-01-01

    Ten patients with congestive heart failure underwent noninvasive and invasive hemodynamic testing before and sequentially after the administration of ibopamine to determine the cardiovascular effects of this oral dopamine congener. Single doses of 200, 400 and 600 mg were administered to all patients and 5 repeated doses of 200 or 400 mg were studied in 8. Hemodynamic effects occurred as early as 30 minutes and lasted up to 4 hours after dosing. In general, ibopamine elicited statistically significant dose-related increases in cardiac output and reductions in the derived resistance of the systemic and pulmonary circulations. A biphasic response in central and peripheral pressures was observed; up to 1 hour after administration, ibopamine elevated mean right and left atrial pressures and pulmonary and systemic arterial pressures with a significant reduction of these measurements beyond 1 hour. It did not alter heart rate. Repeated doses qualitatively affected hemodynamics similar to the initial dose and did not appear to be accompanied by short-term tolerance. While oral ibopamine elicits some favorable hemodynamic effects in humans with cardiac failure, the biphasic hemodynamic response is generally undesirable in the majority of these patients.

  9. A Signal Processing Approach for Detection of Hemodynamic Instability before Decompensation

    PubMed Central

    Belle, Ashwin; Ansari, Sardar; Spadafore, Maxwell; Convertino, Victor A.; Ward, Kevin R.; Derksen, Harm; Najarian, Kayvan

    2016-01-01

    Advanced hemodynamic monitoring is a critical component of treatment in clinical situations where aggressive yet guided hemodynamic interventions are required in order to stabilize the patient and optimize outcomes. While there are many tools at a physician’s disposal to monitor patients in a hospital setting, the reality is that none of these tools allow hi-fidelity assessment or continuous monitoring towards early detection of hemodynamic instability. We present an advanced automated analytical system which would act as a continuous monitoring and early warning mechanism that can indicate pending decompensation before traditional metrics can identify any clinical abnormality. This system computes novel features or bio-markers from both heart rate variability (HRV) as well as the morphology of the electrocardiogram (ECG). To compare their effectiveness, these features are compared with the standard HRV based bio-markers which are commonly used for hemodynamic assessment. This study utilized a unique database containing ECG waveforms from healthy volunteer subjects who underwent simulated hypovolemia under controlled experimental settings. A support vector machine was utilized to develop a model which predicts the stability or instability of the subjects. Results showed that the proposed novel set of features outperforms the traditional HRV features in predicting hemodynamic instability. PMID:26871715

  10. A Signal Processing Approach for Detection of Hemodynamic Instability before Decompensation.

    PubMed

    Belle, Ashwin; Ansari, Sardar; Spadafore, Maxwell; Convertino, Victor A; Ward, Kevin R; Derksen, Harm; Najarian, Kayvan

    2016-01-01

    Advanced hemodynamic monitoring is a critical component of treatment in clinical situations where aggressive yet guided hemodynamic interventions are required in order to stabilize the patient and optimize outcomes. While there are many tools at a physician's disposal to monitor patients in a hospital setting, the reality is that none of these tools allow hi-fidelity assessment or continuous monitoring towards early detection of hemodynamic instability. We present an advanced automated analytical system which would act as a continuous monitoring and early warning mechanism that can indicate pending decompensation before traditional metrics can identify any clinical abnormality. This system computes novel features or bio-markers from both heart rate variability (HRV) as well as the morphology of the electrocardiogram (ECG). To compare their effectiveness, these features are compared with the standard HRV based bio-markers which are commonly used for hemodynamic assessment. This study utilized a unique database containing ECG waveforms from healthy volunteer subjects who underwent simulated hypovolemia under controlled experimental settings. A support vector machine was utilized to develop a model which predicts the stability or instability of the subjects. Results showed that the proposed novel set of features outperforms the traditional HRV features in predicting hemodynamic instability.

  11. All purpose railroad car

    SciTech Connect

    Terlecky, B.S.

    1987-01-13

    An all purpose railroad car is described for transporting wheeled trailers and containers, the car comprising an elongated frame supported by wheel trucks, combined hitch and bolster means adjacent one end of the frame for selectively receiving and releasably retaining a trailer king pin and one end of a container. A means is spaced from the combined hitch and bolster means for selectively receiving and supporting the wheels of a wheeled trailer and the other end of a container. The combined hitch and bolster means is an integral rigid structure with the hitch fixed in spaced relationship to the bolster with both the hitch and the bolster permanently disposed in operative position to respectively receive and retain a trailer king pin and a container.

  12. [Patients with hemodynamic unstable pelvic fractures in extremis: pelvic packing or angiography?].

    PubMed

    Liñán-Padilla, A; Giráldez-Sánchez, M Á; Serrano-Toledano, D; Lázaro-Gonzálvez, A; Cano-Luís, P

    2013-01-01

    The multidisciplinary management of patients with pelvic trauma has improved prognosis, but mortality is still very high. The appropriate treatment strategy remains controversial, especially regarding the control of bleeding in patients whose clinical situation is extreme by using angiography or pelvic packing. We propose using a tool of evidence-based medicine (CAT) the benefit of the completion of pelvic packing in relation to a specific clinical question from a specific situation. What is best for the management of bleeding, extraperitoneal pelvic packing or angiography, in patients with hemodynamically unstable pelvic fracture in extremis? From this study we can conclude that angiography may improve control of bleeding in patients with arterial bleeding and hemodynamically stable but the packing has priority in patients with pelvic fractures and hemodynamic instability.

  13. Simultaneous measurement of hemorheological and hemodynamic properties using a rat extracorporeal model

    NASA Astrophysics Data System (ADS)

    Yeom, Eunseop; Lee, Sang Joon; CenterBiofluid; Biomimetics Research Team

    2015-11-01

    It is well known that cardiovascular diseases (CVDs) are closely related with the variations of hemorheological and hemodynamic properties. Accurate measurement of these properties is essential for early diagnosis of CVDs. However, in vitro measurements have technical limitation for the accurate measurement because in vitro exposure can change hemorheological properties. To resolve this problem, a rat extracorporeal model which connects the artery and vein in a rat was employed in this study. Blood flows in the rat extracorporeal model were visualized by an ultrasound imaging system and microfluidic devices for monitoring hemorheological and hemodynamic properties. As a result, the system can be effectively used to measure blood viscosity, red blood cell aggregation and flow rate under ex vivo conditions. The present results would be helpful to develop a diagnostic modality for monitoring the variations in hemorheological and hemodynamic parameters. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP) (No. 2008-0061991).

  14. Utility of Functional Hemodynamics and Echocardiography to Aid Diagnosis and Management of Shock.

    PubMed

    McGee, William T; Raghunathan, Karthik; Adler, Adam C

    2015-12-01

    The utility of functional hemodynamics and bedside ultrasonography is increasingly recognized as advantageous for both improved diagnosis and management of shock states. In contrast to conventional "static" measures, "dynamic" hemodynamic measures and bedside imaging modalities enhance pathophysiology-based comprehensive understanding of shock states and the response to therapy. The current editions of major textbooks in the primary specialties--in which clinicians routinely encounter patients in shock--including surgery, anesthesia, emergency medicine, and internal medicine continue to incorporate traditional (conventional) descriptions of shock that use well-described (but potentially misleading) intravascular pressures to classify shock states. Reliance on such intravascular pressure measurements is not as helpful as newer "dynamic" functional measures including ultrasonography to both better assess volume responsiveness and biventricular cardiac function. This review thus emphasizes the application of current functional hemodynamics and ultrasonography to the diagnosis and management of shock as a contrast to conventional "static" pressure-based measures.

  15. Hemodynamic changes and baroreflex sensitivity associated with carotid endarterectomy and carotid artery stenting.

    PubMed

    Cao, Qinqin; Zhang, Jun; Xu, Gelin

    2015-01-01

    Atherosclerotic carotid lesion is a major cause of stroke which accounts for up to 20% of ischemic stroke. Aggressive treatment of carotid stenosis may prevent stroke. Currently, carotid endarterectomy (CEA) and carotid artery stenting (CAS) are the first-line treatments for severe carotid stenosis. CEA is superior to medical therapy in preventing stroke and cardiovascular death. CAS has emerged as an alternative to CEA in recent years due to its less invasive nature. However, both CEA and CAS may be associated with adverse hemodynamic changes as well as a variation of carotid baroreflex sensitivity. There is no consensus on which of these two methods is more advantageous concerning the procedure-related hemodynamic changes. This article reviews the hemodynamic changes and baroreflex sensitivity after CEA and CAS. PMID:25999987

  16. The influence of stenosis degrees and graft suture position on local hemodynamics of coronary bypass

    NASA Astrophysics Data System (ADS)

    Totorean, A. F.; Bernad, S. I.; Susan-Resiga, R. F.

    2016-06-01

    Bypass graft failure is mainly caused by intimal hyperplasia (IH) that occurs at the graft anastomosis after coronary artery bypass grafting (CABG) surgery. It has been shown that local hemodynamics influences the process of IH initiation and progression. A main concern at this type of surgery is to increase the graft patency, respectively to improve the local hemodynamics. This paper analyzes the influence of different degree of stenosis severity and graft suture position on graft patency, taking into consideration the local hemodynamics. Bypass configurations with anastomosis angle of 45° were numerically investigated, with respect to wall shear stress and pressure variation. We can assume that in the conditions of our study, different stenosis degrees and position of the graft suture influence the local blood flow conditions, and, nevertheless, the graft patency.

  17. Taurine, cardiopulmonary hemodynamics, and pulmonary hypertension syndrome in broilers.

    PubMed

    Ruiz-Feria, C A; Wideman, R F

    2001-11-01

    Previous studies have suggested cardiac taurine is released into the plasma in response to hypoxemia (low blood oxygen levels) during the pathogenesis of pulmonary hypertension syndrome (PHS, ascites). In the present study, broilers reared under cool temperature conditions (16 C) were provided tap water (control group), tap water supplemented with taurine, or tap water supplemented with the taurine transport antagonist beta-alanine. When compared with control values, taurine supplementation consistently elevated free taurine concentrations in the plasma but not in cardiac tissues, whereas beta-alanine supplementation consistently reduced free taurine concentrations in cardiac tissues but not in the plasma. Neither the incidence of PHS nor specific predictors of PHS susceptibility (electrocardiogram Lead II S-wave amplitude, % saturation of hemoglobin with oxygen, heart rate, right to total ventricular weight ratio) were affected by taurine or beta-alanine supplementation. Cardiopulmonary hemodynamic evaluations were conducted to compare control and beta-alanine supplemented broilers breathing room air or air containing 12% oxygen (low oxygen challenge). While breathing room air, the betaalanine-supplemented broilers had higher baseline values for cardiac output (186.2 vs. 146.9 mL/min/kg BW) and pulmonary arterial pressure (27.4 vs. 22.4 mm Hg), similar values for mean systemic arterial pressure (100 vs. 104 mm Hg) and pulmonary vascular resistance (0.062 vs. 0.064 resistance units), and lower values for total peripheral resistance (0.228 vs. 0.296 resistance units) when compared with control broilers breathing room air. During low oxygen challenges, the beta-alanine-supplemented broilers exhibited larger reductions in cardiac output, mean systemic arterial pressure, and pulmonary arterial pressure and greater increases in pulmonary vascular resistance than control broilers. These observations indicate that beta-alanine-supplemented broilers breathing room air had

  18. Regulation of Renal Hemodynamics and Function by RGS2.

    PubMed

    Osei-Owusu, Patrick; Owens, Elizabeth A; Jie, Li; Reis, Janaina S; Forrester, Steven J; Kawai, Tatsuo; Eguchi, Satoru; Singh, Harpreet; Blumer, Kendall J

    2015-01-01

    Regulator of G protein signaling 2 (RGS2) controls G protein coupled receptor (GPCR) signaling by acting as a GTPase-activating protein for heterotrimeric G proteins. Certain Rgs2 gene mutations have been linked to human hypertension. Renal RGS2 deficiency is sufficient to cause hypertension in mice; however, the pathological mechanisms are unknown. Here we determined how the loss of RGS2 affects renal function. We examined renal hemodynamics and tubular function by monitoring renal blood flow (RBF), glomerular filtration rate (GFR), epithelial sodium channel (ENaC) expression and localization, and pressure natriuresis in wild type (WT) and RGS2 null (RGS2-/-) mice. Pressure natriuresis was determined by stepwise increases in renal perfusion pressure (RPP) and blood flow, or by systemic blockade of nitric oxide synthase with L-NG-Nitroarginine methyl ester (L-NAME). Baseline GFR was markedly decreased in RGS2-/- mice compared to WT controls (5.0 ± 0.8 vs. 2.5 ± 0.1 μl/min/g body weight, p<0.01). RBF was reduced (35.4 ± 3.6 vs. 29.1 ± 2.1 μl/min/g body weight, p=0.08) while renal vascular resistance (RVR; 2.1 ± 0.2 vs. 3.0 ± 0.2 mmHg/μl/min/g body weight, p<0.01) was elevated in RGS2-/- compared to WT mice. RGS2 deficiency caused decreased sensitivity and magnitude of changes in RVR and RBF after a step increase in RPP. The acute pressure-natriuresis curve was shifted rightward in RGS2-/- relative to WT mice. Sodium excretion rate following increased RPP by L-NAME was markedly decreased in RGS2-/- mice and accompanied by increased translocation of ENaC to the luminal wall. We conclude that RGS2 deficiency impairs renal function and autoregulation by increasing renal vascular resistance and reducing renal blood flow. These changes impair renal sodium handling by favoring sodium retention. The findings provide a new line of evidence for renal dysfunction as a primary cause of hypertension. PMID:26193676

  19. Regulation of Renal Hemodynamics and Function by RGS2

    PubMed Central

    Osei-Owusu, Patrick; Owens, Elizabeth A.; Jie, Li; Reis, Janaina S.; Forrester, Steven J.; Kawai, Tatsuo; Eguchi, Satoru; Singh, Harpreet; Blumer, Kendall J.

    2015-01-01

    Regulator of G protein signaling 2 (RGS2) controls G protein coupled receptor (GPCR) signaling by acting as a GTPase-activating protein for heterotrimeric G proteins. Certain Rgs2 gene mutations have been linked to human hypertension. Renal RGS2 deficiency is sufficient to cause hypertension in mice; however, the pathological mechanisms are unknown. Here we determined how the loss of RGS2 affects renal function. We examined renal hemodynamics and tubular function by monitoring renal blood flow (RBF), glomerular filtration rate (GFR), epithelial sodium channel (ENaC) expression and localization, and pressure natriuresis in wild type (WT) and RGS2 null (RGS2-/-) mice. Pressure natriuresis was determined by stepwise increases in renal perfusion pressure (RPP) and blood flow, or by systemic blockade of nitric oxide synthase with L-NG-Nitroarginine methyl ester (L-NAME). Baseline GFR was markedly decreased in RGS2-/- mice compared to WT controls (5.0 ± 0.8 vs. 2.5 ± 0.1 μl/min/g body weight, p<0.01). RBF was reduced (35.4 ± 3.6 vs. 29.1 ± 2.1 μl/min/g body weight, p=0.08) while renal vascular resistance (RVR; 2.1 ± 0.2 vs. 3.0 ± 0.2 mmHg/μl/min/g body weight, p<0.01) was elevated in RGS2-/- compared to WT mice. RGS2 deficiency caused decreased sensitivity and magnitude of changes in RVR and RBF after a step increase in RPP. The acute pressure–natriuresis curve was shifted rightward in RGS2-/- relative to WT mice. Sodium excretion rate following increased RPP by L-NAME was markedly decreased in RGS2-/- mice and accompanied by increased translocation of ENaC to the luminal wall. We conclude that RGS2 deficiency impairs renal function and autoregulation by increasing renal vascular resistance and reducing renal blood flow. These changes impair renal sodium handling by favoring sodium retention. The findings provide a new line of evidence for renal dysfunction as a primary cause of hypertension. PMID:26193676

  20. Resolution and outcome of acute circulatory failure does not correlate with hemodynamics

    PubMed Central

    Suistomaa, Matti; Uusaro, Ari; Parviainen, Ilkka; Ruokonen, Esko

    2003-01-01

    Introduction Hemodynamic goals in the treatment of acute circulatory failure (ACF) are controversial. In critical care, organ failures can be assessed using Sequential Organ Failure Assessment and its refinement, total maximal Sequential Organ Failure Assessment (TMS). We studied the associations between resolution of ACF and hemodynamics in the early (< 24 hours) phase of intensive care unit care and their relation to TMS and mortality. Patients and methods Eighty-three patients with ACF (defined as arterial lactate > 2 mmol/l and/or base deficit > 4) who had pulmonary artery catheters and stayed for longer than 24 hours in the intensive care unit were included. Hemodynamics, oxygen transport, vasoactive drugs and TMS scores were recorded. Normalisation of hyperlactatemia and metabolic acidosis in less than 24 hours after admission was defined as a positive response to hemodynamic resuscitation. Results Fifty-two patients responded to resuscitation. Nonresponders had higher mortality than responders (52% versus 33%, P = 0.044). Hospital mortality was highest (63%) among nonresponders who received vasoactive drugs. The TMS scores of nonresponders (median [interquartile range], 12 [9-16]) were higher than the scores of responders (10 [7-12], P = 0.019). Late accumulation of TMS scores was associated with increasing mortality, and if the TMS score increase occurred > 5 days after admission then the mortality was 77%. Responders had higher mean arterial pressure at 24 hours, but it was no different between survivors and nonsurvivors. No other hemodynamic and oxygen transport variables were associated with the success of resuscitation or with mortality. Conclusions Except for the mean arterial pressure at 24 hours, invasively derived hemodynamic and oxygen transport variables are not associated with the response to resuscitation or with mortality. Positive response to resuscitation in ACF is associated with less severe organ failures as judged by TMS scores. Late

  1. Non-invasive measurements of tissue hemodynamics with hybrid diffuse optical methods

    NASA Astrophysics Data System (ADS)

    Durduran, Turgut

    Diffuse optical techniques were used to measure hemodynamics of tissues non-invasively. Spectroscopy and tomography of the brain, muscle and implanted tumors were carried out in animal models and humans. Two qualitatively different methods, diffuse optical tomography and diffuse correlation tomography, were hybridized permitting simultaneous measurement of total hemoglobin concentration, blood oxygen saturation and blood flow. This combination of information was processed further to derive estimates of oxygen metabolism (e.g. CMRO 2) in tissue. The diffuse correlation measurements of blood flow were demonstrated in human tissues, for the first time, demonstrating continous, non-invasive imaging of oxygen metabolism in large tissue volumes several centimeters below the tissue surface. The bulk of these investigations focussed on cerebral hemodynamics. Extensive validation of this methodology was carried out in in vivo rat brain models. Three dimensional images of deep tissue hemodynamics in middle cerebral artery occlusion and cortical spreading depression (CSD) were obtained. CSD hemodynamics were found to depend strongly on partial pressure of carbon dioxide. The technique was then adapted for measurement of human brain. All optical spectroscopic measurements of CMRO2 during functional activation were obtained through intact human skull non-invasively. Finally, a high spatio-temporal resolution measurement of cerebral blood flow due to somatosensory cortex activation following electrical forepaw stimulation in rats was carried out with laser speckle flowmetry. New analysis methods were introduced for laser speckle flowmetry. In other organs, deep tissue hemodynamics were measured on human calf muscle during exercise and cuff-ischemia and were shown to have some clinical utility for peripheral vascular disease. In mice tumor models, the measured hemodynamics were shown to be predictive of photodynamic therapy efficacy, again suggesting promise of clinical utility

  2. Hemodynamic responses to continuous versus pulsatile mechanical unloading of the failing left ventricle.

    PubMed

    Bartoli, Carlo R; Giridharan, Guruprasad A; Litwak, Kenneth N; Sobieski, Michael; Prabhu, Sumanth D; Slaughter, Mark S; Koenig, Steven C

    2010-01-01

    Debate exists regarding the merits and limitations of continuous versus pulsatile flow mechanical circulatory support. To characterize the hemodynamic differences between each mode of support, we investigated the acute effects of continuous versus pulsatile unloading of the failing left ventricle in a bovine model. Heart failure was induced in male calves (n = 14). During an acute study, animals were instrumented through thoracotomy for hemodynamic measurement. A continuous flow (n = 8) and/or pulsatile flow (n = 8) left ventricular assist device (LVAD) was implanted and studied during maximum support ( approximately 5 L/min) and moderate support ( approximately 2-3 L/min) modes. Pulse pressure (PP), surplus hemodynamic energy (SHE), and (energy equivalent pressure [EEP]/mean aortic pressure (MAP) - 1) x 100% were derived to characterize hemodynamic energy profiles during the different support modes. Standard hemodynamic parameters of cardiac performance were also derived. Data were analyzed by repeated measures one-way analysis of variance within groups and unpaired Student's t-tests across groups. During maximum and moderate continuous unloading, PP, SHE, and (EEP/MAP - 1) x 100% were significantly decreased compared with baseline and compared with pulsatile unloading. As a result, continuous unloading significantly altered left ventricular peak systolic pressure, aortic systolic and diastolic pressure, +/-dP/dt, and rate x pressure product, whereas pulsatile unloading preserved a normal profile of physiologic values. As continuous unloading increased, the pressure-volume relationship collapsed, and the aortic valve remained closed. In contrast, as pulsatile unloading increased, a comparable decrease in left ventricular volumes was noted. However, a normal range of left ventricular pressures was preserved. Continuous unloading deranged the physiologic profile of myocardial and vascular hemodynamic energy utilization, whereas pulsatile unloading preserved more

  3. SvO(2)-guided resuscitation for experimental septic shock: effects of fluid infusion and dobutamine on hemodynamics, inflammatory response, and cardiovascular oxidative stress.

    PubMed

    Rosário, André Loureiro; Park, Marcelo; Brunialti, Milena Karina; Mendes, Marialice; Rapozo, Marjorie; Fernandes, Denise; Salomão, Reinaldo; Laurindo, Francisco Rafael; Schettino, Guilherme Paula; Azevedo, Luciano Cesar P

    2011-12-01

    The pathogenetic mechanisms associated to the beneficial effects of mixed venous oxygen saturation (SvO(2))-guided resuscitation during sepsis are unclear. Our purpose was to evaluate the effects of an algorithm of SvO(2)-driven resuscitation including fluids, norepinephrine and dobutamine on hemodynamics, inflammatory response, and cardiovascular oxidative stress during a clinically resembling experimental model of septic shock. Eighteen anesthetized and catheterized pigs (35-45 kg) were submitted to peritonitis by fecal inoculation (0.75 g/kg). After hypotension, antibiotics were administered, and the animals were randomized to two groups: control (n = 9), with hemodynamic support aiming central venous pressure 8 to 12 mmHg, urinary output 0.5 mL/kg per hour, and mean arterial pressure greater than 65 mmHg; and SvO(2) (n = 9), with the goals above, plus SvO(2) greater than 65%. The interventions lasted 12 h, and lactated Ringer's and norepinephrine (both groups) and dobutamine (SvO(2) group) were administered. Inflammatory response was evaluated by plasma concentration of cytokines, neutrophil CD14 expression, oxidant generation, and apoptosis. Oxidative stress was evaluated by plasma and myocardial nitrate concentrations, myocardial and vascular NADP(H) oxidase activity, myocardial glutathione content, and nitrotyrosine expression. Mixed venous oxygen saturation-driven resuscitation was associated with improved systolic index, oxygen delivery, and diuresis. Sepsis induced in both groups a significant increase on IL-6 concentrations and plasma nitrate concentrations and a persistent decrease in neutrophil CD14 expression. Apoptosis rate and neutrophil oxidant generation were not different between groups. Treatment strategies did not significantly modify oxidative stress parameters. Thus, an approach aiming SvO(2) during sepsis improves hemodynamics, without any significant effect on inflammatory response and oxidative stress. The beneficial effects associated

  4. Rapid Cerebral Hemodynamic Modulation during Set Shifting: Evidence of Time-Locked Associations with Cognitive Control in Females

    ERIC Educational Resources Information Center

    Schuepbach, Daniel; Huizinga, Mariette; Duschek, Stefan; Grimm, Simone; Boeker, Heinz; Hell, Daniel

    2009-01-01

    Set shifting provokes specific alterations of cerebral hemodynamics in basal cerebral arteries. However, no gender differences have been reported. In the following functional transcranial Doppler study, we introduced cerebral hemodynamic modulation to the aspects of set shifting during Wisconsin Card Sorting Test (WCST). Twenty-one subjects…

  5. [YAKTON INFLUENCE ON THE RABBITS CARDIAC ACTIVITY AND SYSTEMI HEMODYNAMIC IN THE CONDITIONS OF 5-FLUOROURACILUM INTOXICATION].

    PubMed

    Maksimchuk, E A

    2015-01-01

    In the experiments on the rabbits the disturbances of cardio and systemic hemodynamic after 5-fluorouracilum administration have been shown. Yakton administercd intravenously in dose 560 mg/ kg one hour before 5-fluorouracilum protects the disturbances of cardio- and systemic hemodynamic data in animals. PMID:26827456

  6. On the complexity of scoring acute respiratory distress syndrome: do not forget hemodynamics!

    PubMed

    Repessé, Xavier; Aubry, Alix; Vieillard-Baron, Antoine

    2016-08-01

    Acute respiratory distress syndrome (ARDS) remains associated with a poor outcome despite recent major therapeutic advances. Forecasting the outcome of patients suffering from such a syndrome is of a crucial interest and many scores have been proposed, all suffering from limits responsible for important discrepancies. Authors try to elaborate simple, routine and reliable scores but most of them do not consider hemodynamics yet acknowledged as a major determinant of outcome. This article aims at reminding the approach of scoring in ARDS and at deeply describing the most recently published one in order to highlight their main pitfall, which is to forget the hemodynamics. PMID:27618840

  7. On the complexity of scoring acute respiratory distress syndrome: do not forget hemodynamics!

    PubMed Central

    Repessé, Xavier; Aubry, Alix

    2016-01-01

    Acute respiratory distress syndrome (ARDS) remains associated with a poor outcome despite recent major therapeutic advances. Forecasting the outcome of patients suffering from such a syndrome is of a crucial interest and many scores have been proposed, all suffering from limits responsible for important discrepancies. Authors try to elaborate simple, routine and reliable scores but most of them do not consider hemodynamics yet acknowledged as a major determinant of outcome. This article aims at reminding the approach of scoring in ARDS and at deeply describing the most recently published one in order to highlight their main pitfall, which is to forget the hemodynamics. PMID:27618840

  8. On the complexity of scoring acute respiratory distress syndrome: do not forget hemodynamics!

    PubMed Central

    Repessé, Xavier; Aubry, Alix

    2016-01-01

    Acute respiratory distress syndrome (ARDS) remains associated with a poor outcome despite recent major therapeutic advances. Forecasting the outcome of patients suffering from such a syndrome is of a crucial interest and many scores have been proposed, all suffering from limits responsible for important discrepancies. Authors try to elaborate simple, routine and reliable scores but most of them do not consider hemodynamics yet acknowledged as a major determinant of outcome. This article aims at reminding the approach of scoring in ARDS and at deeply describing the most recently published one in order to highlight their main pitfall, which is to forget the hemodynamics.

  9. Hemodynamic management of septic shock: is it time for "individualized goal-directed hemodynamic therapy" and for specifically targeting the microcirculation?

    PubMed

    Saugel, Bernd; Trepte, Constantin J; Heckel, Kai; Wagner, Julia Y; Reuter, Daniel A

    2015-06-01

    Septic shock is a life-threatening condition in both critically ill medical patients and surgical patients during the perioperative phase. In septic shock, specific alterations in global cardiovascular dynamics (i.e., the macrocirculation) and in the microcirculatory blood flow (i.e., the microcirculation) have been described. However, the presence and degree of microcirculatory failure are in part independent from systemic macrohemodynamic variables. Macrocirculatory and microcirculatory failure can independently induce organ dysfunction. We review current diagnostic and therapeutic approaches for the assessment and optimization of both the macrocirculation and the microcirculation in septic shock. There are various technologies for the determination of macrocirculatory hemodynamic variables. We discuss the data on early goal-directed therapy for the resuscitation of the macrocirculation. In addition, we describe the concept of "individualized goal-directed hemodynamic therapy." Technologies to assess the local microcirculation are also available. However, adequate resuscitation goals for the optimization of the microcirculation still need to be defined. At present, we are not ready to specifically monitor and target the microcirculation in clinical routine outside studies. In the future, concepts for an integrative approach for individualized hemodynamic management of the macrocirculation and in parallel the microcirculation might constitute a huge opportunity to define additional resuscitation end points in septic shock.

  10. Hemodynamic and thrombogenic analysis of a trileaflet polymeric valve using a fluid-structure interaction approach.

    PubMed

    Piatti, Filippo; Sturla, Francesco; Marom, Gil; Sheriff, Jawaad; Claiborne, Thomas E; Slepian, Marvin J; Redaelli, Alberto; Bluestein, Danny

    2015-10-15

    Surgical valve replacement in patients with severe calcific aortic valve disease using either bioprosthetic or mechanical heart valves is still limited by structural valve deterioration for the former and thrombosis risk mandating anticoagulant therapy for the latter. Prosthetic polymeric heart valves have the potential to overcome the inherent material and design limitations of these valves, but their development is still ongoing. The aim of this study was to characterize the hemodynamics and thrombogenic potential of the Polynova polymeric trileaflet valve prototype using a fluid-structure interaction (FSI) approach. The FSI model replicated experimental conditions of the valve as tested in a left heart simulator. Hemodynamic parameters (transvalvular pressure gradient, flow rate, maximum velocity, and effective orifice area) were compared to assess the validity of the FSI model. The thrombogenic footprint of the polymeric valve was evaluated using a Lagrangian approach to calculate the stress accumulation (SA) values along multiple platelet trajectories and their statistical distribution. In the commissural regions, platelets were exposed to the highest SA values because of highest stress levels combined with local reverse flow patterns and vortices. Stress-loading waveforms from representative trajectories in regions of interest were emulated in our hemodynamic shearing device (HSD). Platelet activity was measured using our platelet activation state (PAS) assay and the results confirmed the higher thrombogenic potential of the commissural hotspots. In conclusion, the proposed method provides an in depth analysis of the hemodynamic and thrombogenic performance of the polymer valve prototype and identifies locations for further design optimization.

  11. Augmentation of sensory-evoked hemodynamic response in an early Alzheimer's disease mouse model.

    PubMed

    Kim, Jinho; Jeong, Yong

    2013-01-01

    Based on enlarged blood oxygen level-dependent (BOLD) responses in cognitively normal subjects at risk for Alzheimer's disease (AD), compensatory neuronal hyperactivation has been proposed as an early marker for diagnosis of AD. The BOLD response results from neurovascular coupling, i.e., hemodynamic response induced by neuronal activity. However, there has been no evidence of task-induced increases in hemodynamic response in animal models of AD. Here, we observed an augmented hemodynamic response pattern in a transgenic AβPP(SWE)/PS1ΔE9 mouse model of AD using three in vivo imaging methods: intrinsic optical signal imaging, multi-photon laser scanning microscopy, and laser Doppler flowmetry. Sensory stimulation resulted in augmented and prolonged hemodynamic responses in transgenic mice evidenced by changes in total, oxygenated, and deoxygenated hemoglobin concentration. This difference between transgenic and wild-type mice was significant at 7 months of age when amyloid plaques and cerebral amyloid angiopathy had developed but not at younger or older ages. Correspondingly, sensory stimulation-induced pial arteriole diameter was also augmented and prolonged in transgenic mice at 7 months of age. Cerebral blood flow response in transgenic mice was augmented but not prolonged. These results are consistent with the existence of BOLD signal hyperactivation in non-demented AD-risk human subjects, supporting its potential use as an early diagnostic marker of AD.

  12. Feasibility of In-Vivo Simulation of Acute Hemodynamics in Human Atrial Fibrillation

    PubMed Central

    Sramko, Marek; Wichterle, Dan; Kautzner, Josef

    2016-01-01

    This study evaluated hemodynamic feasibility and reproducibility of a new method for in vivo simulation of human atrial fibrillation (AF). The method was tested during sinus rhythm in 10 patients undergoing catheter ablation for AF. A simple electronic device was assembled that allowed triggering a cardiac stimulator by predefined series of RR intervals. Irregular RR interval sequences with a mean heart rate of 90/min and 130/min were obtained from ECG recordings of another patients with AF. Simultaneous atrioventricular pacing was delivered by catheters placed inside the coronary sinus and at the His bundle region. Hemodynamic effect of the simulated AF was assessed by invasive measurement of the left ventricular (LV) pressure, dP/dt, and Tau. Compared to regular pacing at the same mean heart rate, the simulated AF significantly impaired the LV both systolic and diastolic function. Repeated AF pacing in the same patients generated similar LV hemodynamics. The proposed method provides a realistic and reproducible in-vivo model of AF. It can be exploited for investigation of the hemodynamic consequences of AF in various patient populations. PMID:27764240

  13. Perspective on CFD studies of coronary artery disease lesions and hemodynamics: a review.

    PubMed

    Zhang, Jun-Mei; Zhong, Liang; Su, Boyang; Wan, Min; Yap, Jinq Shya; Tham, Jasmine P L; Chua, Leok Poh; Ghista, Dhanjoo N; Tan, Ru San

    2014-06-01

    Coronary artery disease (CAD) is the most common cardiovascular disease. Early diagnosis of CAD's physiological significance is of utmost importance for guiding individualized risk-tailored treatment strategies. In this paper, we first review the state-of-the-art clinical diagnostic indices to quantify the severity of CAD and the associated invasive and noninvasive imaging technologies in order to quantify the anatomical parameters of diameter stenosis, area stenosis, and hemodynamic indices of coronary flow reserve and fractional flow reserve. With the development of computational technologies and CFD methods, tremendous progress has been made in applying image-based CFD simulation techniques to elucidate the effects of hemodynamics in vascular pathophysiology toward the initialization and progression of CAD. So then, we review the advancements of CFD technologies in patient-specific modeling, involving the development of geometry reconstruction, boundary conditions, and fluid-structure interaction. Next, we review the applications of CFD to stenotic sites, in order to compute their hemodynamic parameters and study the relationship between the hemodynamic conditions and the clinical indices, to thereby assess the amount of viable myocardium and candidacy for percutaneous coronary intervention. Finally, we review the strengths and limitations of current researches of applying CFD to CAD studies.

  14. Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers.

    PubMed

    Son, Taeyoon; Wang, Benquan; Thapa, Damber; Lu, Yiming; Chen, Yanjun; Cao, Dingcai; Yao, Xincheng

    2016-08-01

    Blood flow changes are highly related to neural activities in the retina. It has been reported that neural activity increases when flickering light stimulation of the retina is used. It is known that blood flow changes with flickering light stimulation can be altered in patients with vascular disease and that measurement of flicker-induced vasodilatation is an easily applied tool for monitoring functional microvascular alterations. However, details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood due to the limitation of existing techniques. In this study, flickering light stimulation was applied to mouse retinas to investigate stimulus evoked hemodynamic responses in individual retinal layers. A spectral domain optical coherence tomography (OCT) angiography imaging system was developed to provide dynamic mapping of hemodynamic responses in the ganglion cell layer, inner plexiform layer, outer plexiform layer and choroid layer before, during and after flickering light stimulation. Experimental results showed hemodynamic responses with different magnitudes and time courses in individual retinal layers. We anticipate that the dynamic OCT angiography of stimulus evoked hemodynamic responses can greatly foster the study of neurovascular coupling mechanisms in the retina, promising new biomarkers for retinal disease detection and diagnosis. PMID:27570706

  15. Correlation between Hemodynamics and Treatment Outcome of Intracranial Aneurysms after Intervention with Flow Diverters

    NASA Astrophysics Data System (ADS)

    Paliwal, Nikhil; Damiano, Robert; Davies, Jason; Siddiqui, Adnan; Meng, Hui

    2015-11-01

    Endovascular intervention by Flow Diverter (FD) - a densely woven stent - occludes an aneurysm by inducing thrombosis in the aneurysm sac and reconstructing the vessel. Hemodynamics plays a vital role in the thrombotic occlusion of aneurysms and eventual treatment outcome. CFD analysis of pre- and post-treatment aneurysms not only provides insight of flow modifications by FD, but also allows investigation of interventional strategies and prediction of their outcome. In this study 80 patient-specific aneurysms treated with FDs were retrospectively studied to evaluate the effect of intervention. Out of these cases, 16 required retreatment and thus are considered as having unfavorable outcome. Clinical FD deployment in these cases was simulated using an efficient virtual stenting workflow. CFD analysis was carried out on both pre- and post-treatment cases, and changes in hemodynamic parameters were calculated. Support vector machine algorithm was used to correlate the hemodynamic changes with outcome. Results show that cases having higher flow reduction into the aneurysmal sac have a better likelihood of occlusion. This suggests that changes in hemodynamics can be potentially used to predict the outcome of different clinical intervention strategies in aneurysms. This work was supported by the National Institutes of Health (R01 NS091075).

  16. [The hemodynamic disorders in Sudeck's atrophy and the effect on them of interference therapy].

    PubMed

    Nikolova, L

    1992-01-01

    Interferential currents applied to the forearm fracture region of 80 patients with Sudeck atrophy eliminated hemodynamic changes in the affected limb as shown by capillaroscopy, rheovasography. The effect of the treatment is attributed to recovery of normal blood flow and microcirculation in the region of bone atrophy as well as analgetic action of pulse current. PMID:1384234

  17. [Study of sharing platform of web-based enhanced extracorporeal counterpulsation hemodynamic waveform data].

    PubMed

    Huang, Mingbo; Hu, Ding; Yu, Donglan; Zheng, Zhensheng; Wang, Kuijian

    2011-12-01

    Enhanced extracorporeal counterpulsation (EECP) information consists of both text and hemodynamic waveform data. At present EECP text information has been successfully managed through Web browser, while the management and sharing of hemodynamic waveform data through Internet has not been solved yet. In order to manage EECP information completely, based on the in-depth analysis of EECP hemodynamic waveform file of digital imaging and communications in medicine (DICOM) format and its disadvantages in Internet sharing, we proposed the use of the extensible markup language (XML), which is currently the Internet popular data exchange standard, as the storage specification for the sharing of EECP waveform data. Then we designed a web-based sharing system of EECP hemodynamic waveform data via ASP. NET 2.0 platform. Meanwhile, we specifically introduced the four main system function modules and their implement methods, including DICOM to XML conversion module, EECP waveform data management module, retrieval and display of EECP waveform module and the security mechanism of the system. PMID:22295686

  18. Induced Hypothermia Does Not Harm Hemodynamics after Polytrauma: A Porcine Model

    PubMed Central

    Weuster, Matthias; Mommsen, Philipp; Pfeifer, Roman; Mohr, Juliane; Ruchholtz, Steffen; Flohé, Sascha; Fröhlich, Matthias; Keibl, Claudia; Seekamp, Andreas; van Griensven, Martijn; Witte, Ingo

    2015-01-01

    Background. The deterioration of hemodynamics instantly endangers the patients' life after polytrauma. As accidental hypothermia frequently occurs in polytrauma, therapeutic hypothermia still displays an ambivalent role as the impact on the cardiopulmonary function is not yet fully understood. Methods. We have previously established a porcine polytrauma model including blunt chest trauma, penetrating abdominal trauma, and hemorrhagic shock. Therapeutic hypothermia (34°C) was induced for 3 hours. We documented cardiovascular parameters and basic respiratory parameters. Pigs were euthanized after 15.5 hours. Results. Our polytrauma porcine model displayed sufficient trauma impact. Resuscitation showed adequate restoration of hemodynamics. Induced hypothermia had neither harmful nor major positive effects on the animals' hemodynamics. Though heart rate significantly decreased and mixed venous oxygen saturation significantly increased during therapeutic hypothermia. Mean arterial blood pressure, central venous pressure, pulmonary arterial pressure, and wedge pressure showed no significant differences comparing normothermic trauma and hypothermic trauma pigs during hypothermia. Conclusions. Induced hypothermia after polytrauma is feasible. No major harmful effects on hemodynamics were observed. Therapeutic hypothermia revealed hints for tissue protective impact. But the chosen length for therapeutic hypothermia was too short. Nevertheless, therapeutic hypothermia might be a useful tool for intensive care after polytrauma. Future studies should extend therapeutic hypothermia. PMID:26170533

  19. Hemodynamic study of the elliptic St. Jude Medical valve: A computational study.

    PubMed

    Jahandardoost, Mehdi; Fradet, Guy; Mohammadi, Hadi

    2016-02-01

    Despite successful implantation of St. Jude Medical bileaflet mechanical heart valves, red blood cell lysis and thrombogenic complications associated with these types of valves are yet to be addressed. In our previous study, we proposed an elliptic housing where 10% ovality was applied to the housing of St. Jude Medical valves. Our preliminary results suggested that the overall hemodynamic performance of St. Jude Medical valves improved in both the closing and opening phases. In this study, we evaluated the hemodynamics around the leaflets in the opening phase using a more sophisticated computational platform, computational fluid dynamics. Results suggested both lower shear stress and wall shear stress values and an overall improved hemodynamic performance in the proposed design. This improvement is characterized by lower values of shear stress and wall shear stress in the regions downstream of the leaflets, lower pressure drop across the valve and smaller recirculation zones in the sinuses areas. The proposed design may open a new chapter in the concept of design and hemodynamic improvement of the next generation of mechanical heart valves. PMID:26783246

  20. Posterior reversible encephalopathy syndrome following hemodynamic treatment of aneurysmal subarachnoid hemorrhage-induced vasospasm.

    PubMed

    Awori, Jonathan; Rajajee, Venkatakrishna; Gemmete, Joseph J; Chaudhary, Neeraj; Thompson, B Gregory; Pandey, Aditya S

    2016-04-01

    Posterior reversible encephalopathy syndrome (PRES) is an uncommon but significant complication of hemodynamic therapy after aneurysmal subarachnoid hemorrhage (aSAH)-induced vasospasm. We performed a PubMed literature search for the period January 1999 to January 2015 using the search terms "posterior reversible encephalopathy syndrome", "subarachnoid hemorrhage", "vasospasm", and "hypertensive encephalopathy", and identified nine cases of PRES after aSAH-induced vasospasm in the literature. We also present a 63-year-old man with aSAH complicated by vasospasm treated with hemodynamic augmentation who subsequently developed PRES. Imaging following development of PRES symptoms shows vasogenic edema in the white matter of the parietal and occipital lobes. Age, sex, history of hypertension, and baseline blood pressure were variable among patients in the literature review. In all cases, patients improved both from a radiological and clinical perspective following blood pressure reduction. To summarize, PRES is a rare complication of hemodynamic therapy for vasospasm following aSAH. The literature at the time of writing demonstrates no common pattern with regard to patient demographics, medical history, or mode of treatment for symptomatic vasospasm. Given its sporadic and unpredictable nature, considering PRES in the differential diagnosis is important when addressing neurological decline following hemodynamic treatment of vasospasm related to aSAH. PMID:26755456

  1. Evaluation of hemodynamics changes during interventional stent placement using Doppler optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Vuong, Barry; Genis, Helen; Wong, Ronnie; Ramjist, Joel; Jivraj, Jamil; Farooq, Hamza; Sun, Cuiru; Yang, Victor X. D.

    2015-03-01

    Carotid atherosclerosis is a critical medical concern that can lead to ischemic stroke. Local hemodynamic patterns have also been associated with the development of atherosclerosis, particularly in regions with disturbed flow patterns such as bifurcations. Traditionally, this disease was treated using carotid endarterectomy, however recently there is an increasing trend of carotid artery stenting due to its minimally invasive nature. It is well known that this interventional technique creates changes in vasculature geometry and hemodynamic patterns due to the interaction of stent struts with arterial lumen, and is associated with complications such as distal emboli and restenosis. Currently, there is no standard imaging technique to evaluate regional hemodynamic patterns found in stented vessels. Doppler optical coherence tomography (DOCT) provides an opportunity to identify in vivo hemodynamic changes in vasculature using high-resolution imaging. In this study, blood flow profiles were examined at the bifurcation junction in the internal carotid artery (ICA) in a porcine model following stent deployment. Doppler imaging was further conducted using pulsatile flow in a phantom model, and then compared to computational fluid dynamics (CFD) simulation of a virtual bifurcation to assist with the interpretation of emphin vivo results.

  2. Reconsideration of Hemodynamic Cerebral Ischemia Using Recent PET/SPECT Studies.

    PubMed

    Nakagawara, Jyoji

    2016-01-01

    Hemodynamic cerebral ischemia has been conceptually confirmed by positron emission tomography (PET) imaging, and misery perfusion could be compensated with both vascular and metabolic reserve; however, these compensatory reserve capacities do not always respond in the same manner from short-term to long-term compromise of hemodynamic cerebral ischemia.In patients with acute misery perfusion, CMRO2 is immediately compensated by a marked increase of OEF combined with a limited increase of CBV. In patients with chronic misery perfusion, a moderate increase of OEF is compatible with a moderate increase of CBV, which could correlate with a moderate decrease of vascular reserve (VR). In moyamoya disease with long-standing misery perfusion, hemodynamic cerebral ischemia is initially compensated with a great deal of vasodilation, and can then be followed with an increased OEF in response to the degree of progression.The stage of hemodynamic cerebral ischemia has been defined by an increase of OEF, but could be reconsidered from different patterns of the engagement of compensatory reserve capacities, and misery perfusion could be classified into three subtypes, such as acute, chronic, and long-standing misery perfusion. PMID:27637635

  3. [Study of sharing platform of web-based enhanced extracorporeal counterpulsation hemodynamic waveform data].

    PubMed

    Huang, Mingbo; Hu, Ding; Yu, Donglan; Zheng, Zhensheng; Wang, Kuijian

    2011-12-01

    Enhanced extracorporeal counterpulsation (EECP) information consists of both text and hemodynamic waveform data. At present EECP text information has been successfully managed through Web browser, while the management and sharing of hemodynamic waveform data through Internet has not been solved yet. In order to manage EECP information completely, based on the in-depth analysis of EECP hemodynamic waveform file of digital imaging and communications in medicine (DICOM) format and its disadvantages in Internet sharing, we proposed the use of the extensible markup language (XML), which is currently the Internet popular data exchange standard, as the storage specification for the sharing of EECP waveform data. Then we designed a web-based sharing system of EECP hemodynamic waveform data via ASP. NET 2.0 platform. Meanwhile, we specifically introduced the four main system function modules and their implement methods, including DICOM to XML conversion module, EECP waveform data management module, retrieval and display of EECP waveform module and the security mechanism of the system.

  4. The Hemodynamic Effects of Blood Flow-Arterial Wall Interaction on Cerebral Aneurysms

    NASA Astrophysics Data System (ADS)

    Oshima, Marie

    2005-11-01

    Mechanical stresses such as wall shear induced by blood flow play an important role on cardiovascular diseases and cerebral disorders like arterioscleroses and cerebral aneurysm. In order to obtain a better understanding of mechanism of formation, growth, and rupture of cerebral aneurysm, this paper focuses on investigation of cerebral hemodynamics and its effects on aneurismal wall. The paper mainly consists of three parts. Since it is important to obtain the detailed information on the hemodynamic properties in the cerebral circulatory system, the first part discusses a large-scale hemodynamic simulation of the Cerebral Arterial Circle of Willis. The second part presents the simulation and in-vitro experiment of cerebral aneurysm with the consideration of blood flow-arterial wall interaction. Both simulations in the first and the second parts are conducted in a patient specific manner using medical images and also include modeling of boundary conditions to emulate realistic hemodynamic conditions. The present mathematical model, however, includes only macroscopic mechanical functions. Therefore, in the third part, the paper touches upon on future prospects in modeling of microscopic functions such as the effects of endothelial cells and multi physics functions such as physiological effects.

  5. Hemodynamic response of children with attention-deficit and hyperactive disorder (ADHD) to emotional facial expressions.

    PubMed

    Ichikawa, Hiroko; Nakato, Emi; Kanazawa, So; Shimamura, Keiichi; Sakuta, Yuiko; Sakuta, Ryoichi; Yamaguchi, Masami K; Kakigi, Ryusuke

    2014-10-01

    Children with attention-deficit/hyperactivity disorder (ADHD) have difficulty recognizing facial expressions. They identify angry expressions less accurately than typically developing (TD) children, yet little is known about their atypical neural basis for the recognition of facial expressions. Here, we used near-infrared spectroscopy (NIRS) to examine the distinctive cerebral hemodynamics of ADHD and TD children while they viewed happy and angry expressions. We measured the hemodynamic responses of 13 ADHD boys and 13 TD boys to happy and angry expressions at their bilateral temporal areas, which are sensitive to face processing. The ADHD children showed an increased concentration of oxy-Hb for happy faces but not for angry faces, while TD children showed increased oxy-Hb for both faces. Moreover, the individual peak latency of hemodynamic response in the right temporal area showed significantly greater variance in the ADHD group than in the TD group. Such atypical brain activity observed in ADHD boys may relate to their preserved ability to recognize a happy expression and their difficulty recognizing an angry expression. We firstly demonstrated that NIRS can be used to detect atypical hemodynamic response to facial expressions in ADHD children.

  6. Artifact reduction in long-term monitoring of cerebral hemodynamics using near-infrared spectroscopy

    PubMed Central

    Vinette, Sarah A.; Dunn, Jeff F.; Slone, Edward; Federico, Paolo

    2015-01-01

    Abstract. Near-infrared spectroscopy (NIRS) is a noninvasive neuroimaging technique used to assess cerebral hemodynamics. Its portability, ease of use, and relatively low operational cost lend itself well to the long-term monitoring of hemodynamic changes, such as those in epilepsy, where events are unpredictable. Long-term monitoring is associated with challenges including alterations in behaviors and motion that can result in artifacts. Five patients with epilepsy were assessed for interictal hemodynamic changes and alterations in behavior or motion. Based on this work, visual inspection was used to identify NIRS artifacts during a period of interest, specifically prior to seizures, in four patients. A motion artifact reduction algorithm (MARA, also known as the spline interpolation method) was tested on these data. Alterations in the NIRS measurements often occurred simultaneously with changes in motion and behavior. Occasionally, sharp shift artifacts were observed in the data. When artifacts appeared as sustained baseline shifts in the data, MARA reduced the standard deviation of the data and the appearance improved. We discussed motion and artifacts as challenges associated with long-term monitoring of cerebral hemodynamics in patients with epilepsy and our group’s approach to circumvent these challenges and improve the quality of the data collected. PMID:26158008

  7. Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers

    PubMed Central

    Son, Taeyoon; Wang, Benquan; Thapa, Damber; Lu, Yiming; Chen, Yanjun; Cao, Dingcai; Yao, Xincheng

    2016-01-01

    Blood flow changes are highly related to neural activities in the retina. It has been reported that neural activity increases when flickering light stimulation of the retina is used. It is known that blood flow changes with flickering light stimulation can be altered in patients with vascular disease and that measurement of flicker-induced vasodilatation is an easily applied tool for monitoring functional microvascular alterations. However, details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood due to the limitation of existing techniques. In this study, flickering light stimulation was applied to mouse retinas to investigate stimulus evoked hemodynamic responses in individual retinal layers. A spectral domain optical coherence tomography (OCT) angiography imaging system was developed to provide dynamic mapping of hemodynamic responses in the ganglion cell layer, inner plexiform layer, outer plexiform layer and choroid layer before, during and after flickering light stimulation. Experimental results showed hemodynamic responses with different magnitudes and time courses in individual retinal layers. We anticipate that the dynamic OCT angiography of stimulus evoked hemodynamic responses can greatly foster the study of neurovascular coupling mechanisms in the retina, promising new biomarkers for retinal disease detection and diagnosis. PMID:27570706

  8. Effect of the serotonin antagonist ketanserin on the hemodynamic and morphological consequences of thrombotic infarction

    SciTech Connect

    Dietrich, W.D.; Busto, R.; Ginsberg, M.D. )

    1989-12-01

    The effect of the serotonin (5-hydroxytryptamine, 5-HT) antagonist ketanserin on the remote hemodynamic consequences of thrombotic brain infarction was studied in rats. Treated rats received an injection of 1 mg/kg ketanserin 30 min before and 1 h following photochemically induced cortical infarction. Local CBF (LCBF) was assessed autoradiographically with ({sup 14}C)iodoantipyrine 4 h following infarction, and chronic infarct size was documented at 5 days. Thrombotic infarction led to significant decreases in LCBF within noninfarcted cortical regions. For example, mean LCBF was decreased to 63, 55, and 65% of control (nontreated normal rats) in ipsilateral frontal, lateral, and auditory cortices, respectively. In rats treated with ketanserin, significant decreases in LCBF were not documented within remote cortical areas compared with controls. In contrast to these hemodynamic effects, morphological analysis of chronic infarct size demonstrated no differences in infarct volume between treated (27 +/- 3 mm3) and nontreated (27 +/- 6 mm3) rats. These data are consistent with the hypothesis that 5-HT is involved in the widespread hemodynamic consequences of experimentally induced thrombotic infarction. Remote hemodynamic consequences of acute infarction can be inhibited without altering final infarct size.

  9. Laser Speckle Flowmetry Method for Measuring Spatial and Temporal Hemodynamic Alterations Throughout Large Microvascular Networks

    PubMed Central

    Meisner, Joshua K.; Sumer, Suna; Murrell, Kelsey P.; Higgins, Timothy J.; Price, Richard J.

    2012-01-01

    Objectives 1) Develop and validate laser speckle flowmetry (LSF) as a quantitative tool for individual microvessel hemodynamics in large networks. 2) Use LSF to determine if structural differences in the dorsal skinfold microcirculation (DSFWC) of C57BL/6 and BALB/c mice impart differential network hemodynamic responses to occlusion. Methods We compared LSF velocity measurements to known/measured velocities in vitro using capillary tube tissue phantoms and in vivo using mouse DSFWCs and cremaster muscles. Hemodynamic changes induced by feed arteriole occlusion were measured using LSF in DSFWCs implanted on C57BL/6 and BALB/c. Results In vitro, we found that the normalized speckle intensity (NSI) versus velocity linear relationship (R2≥0.97) did not vary with diameter or hematocrit and can be shifted to meet an expected operating range. In vivo, DSFWC and cremaster muscle preparations (R2=0.92 and 0.95, respectively) demonstrated similar linear relationships between NSI and centerline velocity. Stratification of arterioles into predicted collateral pathways revealed significant differences between C57BL/6 and BALB/c strains in response to feed arteriole occlusion. Conclusions These data demonstrate the applicability of LSF to intravital microscopy microcirculation preparations for determining both relative and absolute hemodynamics on a network-wide scale while maintaining the resolution of individual microvessels. PMID:22591575

  10. Simultaneous measurement of neuronal activity and cortical hemodynamics by unshielded magnetoencephalography and near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Seki, Yusuke; Miyashita, Tsuyoshi; Kandori, Akihiko; Maki, Atsushi; Koizumi, Hideaki

    2012-10-01

    The correlation between neuronal activity and cortical hemodynamics, namely, neurovascular coupling (NVC), is important to shed light on the mechanism of a variety of brain functions or neuronal diseases. NVC can be studied by simultaneously measuring neuronal activity and cortical hemodynamics. Consequently, noninvasive measurements of the NVC have been widely studied using both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). However, electromagnetic interference between EEG and fMRI is still a major problem. On the other hand, near-infrared spectroscopy (NIRS) is another promising tool for detecting cortical hemodynamics because it can be combined with EEG or magnetoencephalography (MEG) without any electromagnetic interference. Accordingly, in the present study, a simultaneous measurement system-combining an unshielded MEG using a two-dimensional gradiometer based on a low-T superconducting quantum interference device (SQUID) and an NIRS using nonmagnetic thin probes-was developed. This combined system was used to simultaneously measure both an auditory-evoked magnetic field and blood flow change in the auditory cortex. It was experimentally demonstrated that the combined unshielded MEG/NIRS system can simultaneously measure neuronal activity and cortical hemodynamics.

  11. [Characteristic features of systemic hemodynamics during cesarean section under general anesthesia with ketamine].

    PubMed

    Moiseev, V N

    1983-02-01

    On the basis of a comparative investigation of the central hemodynamics by the method of integrative rheography of the body in two groups of women during the operation of cesarean section under general anesthesia with ether or ketamin the author makes a conclusion that ketamin is a good drug for anesthesia in urgent surgical situations.

  12. [Prediction of human orthostatic tolerance by changes in arterial and venous hemodynamics in the microgravity environment].

    PubMed

    Kotovskaia, A R; Fomin, G A

    2013-01-01

    The authors intentionally present exclusively the results of their recent studies of arterial and venous hemodynamics as predictors of human orthostatic tolerance (OT) during space flight and on return to Earth. There is a sufficient demonstration of the in-flight OT predictability by arterial hemodynamic reactions to LBNP and venous hemodynamic changes in response to the lower extremities occlusion. Three levels of cerebral blood flow deficits in the course of the lower body negative pressure test (LBNP) performed in microgravity were first defined. The authors offer quantitative arguments for the dependence of cerebral flow deficit on the degree of LBNP tolerance degradation. Patterns of arterial hemodynamics during LBNP were used successfully to diagnose the actual orthostatic tolerance and also to follow its trend as flight extended, which attests to the predictability of OT change in an individual cosmonaut on space flight. Occlusion plethysmography of legs revealed three levels of response of the most informative venous parameters (capacity, distensibility and rate of filling) correlating with severity of OT degradation. PMID:25509869

  13. Noninvasive high-speed photoacoustic tomography of cerebral hemodynamics in awake-moving rats

    PubMed Central

    Tang, Jianbo; Xi, Lei; Zhou, Junli; Huang, Hua; Zhang, Tao; Carney, Paul R; Jiang, Huabei

    2015-01-01

    We present a noninvasive method of photoacoustic tomography (PAT) for imaging cerebral hemodynamics in awake-moving rats. The wearable PAT (wPAT) system has a size of 15 mm in height and 33 mm in diameter, and a weight of ~8 g (excluding cabling). The wPAT achieved an imaging rate of 3.33 frames/s with a lateral resolution of 243 μm. Animal experiments were designed to show wPAT feasibility for imaging cerebral hemodynamics on awake-moving animals. Results showed that the cerebral oxy-hemoglobin and deoxy-hemoglobin changed significantly in response to hyperoxia; and, after the injection of pentylenetetrazol (PTZ), cerebral blood volume changed faster over time and larger in amplitude for rats in awake-moving state compared with rats under anesthesia. By providing a light-weight, high-resolution technology for in vivo monitoring of cerebral hemodynamics in awake-behaving animals, it will be possible to develop a comprehensive understanding on how activity alters hemodynamics in normal and diseased states. PMID:26082016

  14. Computational hemodynamics in cerebral aneurysms: the effects of modeled versus measured boundary conditions.

    PubMed

    Marzo, Alberto; Singh, Pankaj; Larrabide, Ignacio; Radaelli, Alessandro; Coley, Stuart; Gwilliam, Matt; Wilkinson, Iain D; Lawford, Patricia; Reymond, Philippe; Patel, Umang; Frangi, Alejandro; Hose, D Rod

    2011-02-01

    Modeling of flow in intracranial aneurysms (IAs) requires flow information at the model boundaries. In absence of patient-specific measurements, typical or modeled boundary conditions (BCs) are often used. This study investigates the effects of modeled versus patient-specific BCs on modeled hemodynamics within IAs. Computational fluid dynamics (CFD) models of five IAs were reconstructed from three-dimensional rotational angiography (3DRA). BCs were applied using in turn patient-specific phase-contrast-MR (pc-MR) measurements, a 1D-circulation model, and a physiologically coherent method based on local WSS at inlets. The Navier-Stokes equations were solved using the Ansys®-CFX™ software. Wall shear stress (WSS), oscillatory shear index (OSI), and other hemodynamic indices were computed. Differences in the values obtained with the three methods were analyzed using boxplot diagrams. Qualitative similarities were observed in the flow fields obtained with the three approaches. The quantitative comparison showed smaller discrepancies between pc-MR and 1D-model data, than those observed between pc-MR and WSS-scaled data. Discrepancies were reduced when indices were normalized to mean hemodynamic aneurysmal data. The strong similarities observed for the three BCs models suggest that vessel and aneurysm geometry have the strongest influence on aneurysmal hemodynamics. In absence of patient-specific BCs, a distributed circulation model may represent the best option when CFD is used for large cohort studies.

  15. Joint state and parameter estimation of the hemodynamic model by particle smoother expectation maximization method

    NASA Astrophysics Data System (ADS)

    Aslan, Serdar; Taylan Cemgil, Ali; Akın, Ata

    2016-08-01

    Objective. In this paper, we aimed for the robust estimation of the parameters and states of the hemodynamic model by using blood oxygen level dependent signal. Approach. In the fMRI literature, there are only a few successful methods that are able to make a joint estimation of the states and parameters of the hemodynamic model. In this paper, we implemented a maximum likelihood based method called the particle smoother expectation maximization (PSEM) algorithm for the joint state and parameter estimation. Main results. Former sequential Monte Carlo methods were only reliable in the hemodynamic state estimates. They were claimed to outperform the local linearization (LL) filter and the extended Kalman filter (EKF). The PSEM algorithm is compared with the most successful method called square-root cubature Kalman smoother (SCKS) for both state and parameter estimation. SCKS was found to be better than the dynamic expectation maximization (DEM) algorithm, which was shown to be a better estimator than EKF, LL and particle filters. Significance. PSEM was more accurate than SCKS for both the state and the parameter estimation. Hence, PSEM seems to be the most accurate method for the system identification and state estimation for the hemodynamic model inversion literature. This paper do not compare its results with Tikhonov-regularized Newton—CKF (TNF-CKF), a recent robust method which works in filtering sense.

  16. Experimental Comparison of the Hemodynamic Effects of Bifurcating Coronary Stent Implantation Techniques

    NASA Astrophysics Data System (ADS)

    Brindise, Melissa; Vlachos, Pavlos; AETheR Lab Team

    2015-11-01

    Stent implantation in coronary bifurcations imposes unique effects to the blood flow patterns and currently there is no universally accepted stent deployment approach. Despite the fact that stent-induced changes can greatly alter clinical outcomes, no concrete understanding exists regarding the hemodynamic effects of each implantation method. This work presents an experimental evaluation of the hemodynamic differences between implantation techniques. We used four common stent implantation methods including the currently preferred one-stent provisional side branch (PSB) technique and the crush (CRU), Culotte (CUL), and T-stenting (T-PR) two-stent techniques, all deployed by a cardiologist in coronary models. Particle image velocimetry was used to obtain velocity and pressure fields. Wall shear stress (WSS), oscillatory shear index, residence times, and drag and compliance metrics were evaluated and compared against an un-stented case. The results of this study demonstrate that while PSB is preferred, both it and T-PR yielded detrimental hemodynamic effects such as low WSS values. CRU provided polarizing and unbalanced results. CUL demonstrated a symmetric flow field, balanced WSS distribution, and ultimately the most favorable hemodynamic environment.

  17. Comparison of tricuspid and bicuspid aortic valve hemodynamics under steady flow conditions

    NASA Astrophysics Data System (ADS)

    Seaman, Clara; Ward, James; Sucosky, Philippe

    2011-11-01

    The bicuspid aortic valve (BAV), a congenital valvular defect consisting of two leaflets instead of three, is associated with a high prevalence of calcific aortic valve disease (CAVD). CAVD also develops in the normal tricuspid aortic valve (TAV) but its progression in the BAV is more severe and rapid. Although hemodynamic abnormalities are increasingly considered potential pathogenic contributor, the native BAV hemodynamics remain largely unknown. Therefore, this study aims at comparing experimentally the hemodynamic environments in TAV and BAV anatomies. Particle-image velocimetry was used to characterize the flow downstream of a native TAV and a model BAV mounted in a left-heart simulator and subjected to three steady flow rates characterizing different phases of the cardiac cycle. While the TAV developed a jet aligned along the valve axis, the BAV was shown to develop a skewed systolic jet with skewness decreasing with increasing flow rate. Measurement of the transvalvular pressure revealed a valvular resistance up to 50% larger in the BAV than in the TAV. The increase in velocity between the TAV and BAV leads to an increase in shear stress downstream of the valve. This study reveals strong hemodynamic abnormalities in the BAV, which may contribute to CAVD pathogenesis.

  18. School burnout and cardiovascular functioning in young adult males: a hemodynamic perspective.

    PubMed

    May, Ross W; Sanchez-Gonzalez, Marcos A; Brown, Preston C; Koutnik, Andrew P; Fincham, Frank D

    2014-01-01

    This study investigated aortic and brachial hemodynamic functioning that may link school burnout to cardiovascular risk factors. Methodological improvements from previous research were implemented including (1) statistical control of depressive and anxiety symptoms (2) resting, stress-induced and cardiac recovery condition comparisons and (3) use of pulse wave analysis. Forty undergraduate young adult males completed self-report measures of school burnout, trait anxiety and depressive symptoms. Participants then completed a protocol consisting of a 10-min seated rest, 5-min baseline (BASE), 3-min cold pressor test (CPT) and a 3-min recovery period (REC). Indices of brachial and aortic hemodynamics were obtained by means of pulse wave analysis via applanation tonometry. Controlling for anxiety and depressive symptoms, planned contrasts identified no differences in cardiovascular parameters at BASE between participants in burnout and non-burnout groups. However, negative changes in hemodynamic indices occurred in burnout participants at CPT and REC as evidenced by increased aortic and brachial systolic and diastolic blood pressures, increased left ventricular work and increased myocardial oxygen consumption. Findings suggest that school burnout symptoms are associated with cardiac hyperactivity during conditions of cardiac stress and recovery and therefore may be associated with the early manifestations of cardiovascular disease. Future studies are suggested to reveal underlying autonomic mechanisms explaining hemodynamics functioning in individuals with school burnout symptomatology.

  19. Acute effects of ferumoxytol on regulation of renal hemodynamics and oxygenation

    PubMed Central

    Cantow, Kathleen; Pohlmann, Andreas; Flemming, Bert; Ferrara, Fabienne; Waiczies, Sonia; Grosenick, Dirk; Niendorf, Thoralf; Seeliger, Erdmann

    2016-01-01

    The superparamagnetic iron oxide nanoparticle ferumoxytol is increasingly used as intravascular contrast agent in magnetic resonance imaging (MRI). This study details the impact of ferumoxytol on regulation of renal hemodynamics and oxygenation. In 10 anesthetized rats, a single intravenous injection of isotonic saline (used as volume control) was followed by three consecutive injections of ferumoxytol to achieve cumulative doses of 6, 10, and 41 mg Fe/kg body mass. Arterial blood pressure, renal blood flow, renal cortical and medullary perfusion and oxygen tension were continuously measured. Regulation of renal hemodynamics and oxygenation was characterized by dedicated interventions: brief periods of suprarenal aortic occlusion, hypoxia, and hyperoxia. None of the three doses of ferumoxytol resulted in significant changes in any of the measured parameters as compared to saline. Ferumoxytol did not significantly alter regulation of renal hemodynamics and oxygenation as studied by aortic occlusion and hypoxia. The only significant effect of ferumoxytol at the highest dose was a blunting of the hyperoxia-induced increase in arterial pressure. Taken together, ferumoxytol has only marginal effects on the regulation of renal hemodynamics and oxygenation. This makes ferumoxytol a prime candidate as contrast agent for renal MRI including the assessment of renal blood volume fraction. PMID:27436132

  20. Image-based modeling of hemodynamics in coronary artery aneurysms caused by Kawasaki disease.

    PubMed

    Sengupta, Dibyendu; Kahn, Andrew M; Burns, Jane C; Sankaran, Sethuraman; Shadden, Shawn C; Marsden, Alison L

    2012-07-01

    Kawasaki Disease (KD) is the leading cause of acquired pediatric heart disease. A subset of KD patients develops aneurysms in the coronary arteries, leading to increased risk of thrombosis and myocardial infarction. Currently, there are limited clinical data to guide the management of these patients, and the hemodynamic effects of these aneurysms are unknown. We applied patient-specific modeling to systematically quantify hemodynamics and wall shear stress in coronary arteries with aneurysms caused by KD. We modeled the hemodynamics in the aneurysms using anatomic data obtained by multi-detector computed tomography (CT) in a 10-year-old male subject who suffered KD at age 3 years. The altered hemodynamics were compared to that of a reconstructed normal coronary anatomy using our subject as the model. Computer simulations using a robust finite element framework were used to quantify time-varying shear stresses and particle trajectories in the coronary arteries. We accounted for the cardiac contractility and the microcirculation using physiologic downstream boundary conditions. The presence of aneurysms in the proximal coronary artery leads to flow recirculation, reduced wall shear stress within the aneurysm, and high wall shear stress gradients at the neck of the aneurysm. The wall shear stress in the KD subject (2.95-3.81 dynes/sq cm) was an order of magnitude lower than the normal control model (17.10-27.15 dynes/sq cm). Particle residence times were significantly higher, taking 5 cardiac cycles to fully clear from the aneurysmal regions in the KD subject compared to only 1.3 cardiac cycles from the corresponding regions of the normal model. In this novel quantitative study of hemodynamics in coronary aneurysms caused by KD, we documented markedly abnormal flow patterns that are associated with increased risk of thrombosis. This methodology has the potential to provide further insights into the effects of aneurysms in KD and to help risk stratify patients for

  1. Sensitivity of CFD Based Hemodynamic Results in Rabbit Aneurysm Models to Idealizations in Surrounding Vasculature

    PubMed Central

    Zeng, Zijing; Kallmes, David F.; Durka, Michael J.; Ding, Yonghong; Lewis, Debra; Kadirvel, Ramanathan

    2010-01-01

    Computational fluid dynamics (CFD) studies provide a valuable tool for evaluating the role of hemodynamics in vascular diseases such as cerebral aneurysms and atherosclerosis. However, such models necessarily only include isolated segments of the vasculature. In this work, we evaluate the influence of geometric approximations in vascular anatomy on hemodynamics in elastase induced saccular aneurysms in rabbits. One representative high aspect ratio (AR—height/neck width) aneurysm and one low AR aneurysm were created at the origin of the right common carotid artery in two New Zealand white rabbits. Three-dimensional (3D) reconstructions of the aneurysm and surrounding arteries were created using 3D rotational angiographic data. Five models with varying extents of neighboring vasculature were created for both the high and low AR cases. A reference model included the aneurysm sac, left common carotid artery (LCCA), aortic arch, and downstream trifurcation/quadrification. Three-dimensional, pulsatile CFD studies were performed and streamlines, wall shear stress (WSS), oscillatory shear index, and cross sectional velocity were compared between the models. The influence of the vascular domain on intra-aneurysmal hemodynamics varied between the low and high AR cases. For the high AR case, even a simple model including only the aneurysm, a small section of neighboring vasculature, and simple extensions captured the main features of the steamline and WSS distribution predicted by the reference model. However, the WSS distribution in the low AR case was more strongly influenced by the extent of vasculature. In particular, it was necessary to include the downstream quadrification and upstream LCCA to obtain good predictions of WSS. The findings in this work demonstrate the accuracy of CFD results can be compromised if insufficient neighboring vessels are included in studies of hemodynamics in elastase induced rabbit aneurysms. Consideration of aspect ratio, hemodynamic

  2. Oral contraceptive use, muscle sympathetic nerve activity, and systemic hemodynamics in young women

    PubMed Central

    Harvey, Ronee E.; Hart, Emma C.; Charkoudian, Nisha; Curry, Timothy B.; Carter, Jason R.; Fu, Qi; Minson, Christopher T.; Joyner, Michael J.; Barnes, Jill N.

    2015-01-01

    Endogenous female sex hormones influence muscle sympathetic nerve activity (MSNA), a regulator of arterial blood pressure and important factor in hypertension development. While nearly 80% of American women report using hormonal contraceptives sometime during their life, the influence of combined oral contraceptives (OCs) on MSNA and systemic hemodynamics remains equivocal. The goal of this study was to determine if women taking OCs have altered MSNA and hemodynamics (cardiac output and total peripheral resistance) at rest during the placebo phase of OC use compared to women with natural menstrual cycles during the early follicular phase. We retrospectively analyzed data from studies in which healthy, premenopausal women (ages 18–35 years old) participated. We collected MSNA values at rest and hemodynamic measurements in women taking OCs (n=53, 25±4 yr) and women with natural menstrual cycles (n=74, 25±4 yr). Blood pressure was higher in women taking OCs versus those with natural menstrual cycles (mean arterial pressure: 89±1 vs. 85±1 mmHg, respectively; p=0.01), although MSNA was similar in both groups (MSNA burst incidence: 16±1 vs. 18±1 bursts/100 heartbeats, respectively, p=0.19). In a subset of women in which detailed hemodynamic data were available, those taking OCs (n=33) had similar cardiac output (4.9±0.2 vs. 4.7±0.2 L/min, respectively; p=0.47) and total peripheral resistance (19.2±0.8 vs. 20.0±0.9 units, respectively; p=0.51) as women with natural menstrual cycles (n=22). In conclusion, women taking OCs have higher resting blood pressure and similar MSNA and hemodynamics during the placebo phase of OC use compared to naturally menstruating women in the early follicular phase. PMID:26101348

  3. Sensitivity of CFD based hemodynamic results in rabbit aneurysm models to idealizations in surrounding vasculature.

    PubMed

    Zeng, Zijing; Kallmes, David F; Durka, Michael J; Ding, Yonghong; Lewis, Debra; Kadirvel, Ramanathan; Robertson, Anne M

    2010-09-01

    Computational fluid dynamics (CFD) studies provide a valuable tool for evaluating the role of hemodynamics in vascular diseases such as cerebral aneurysms and atherosclerosis. However, such models necessarily only include isolated segments of the vasculature. In this work, we evaluate the influence of geometric approximations in vascular anatomy on hemodynamics in elastase induced saccular aneurysms in rabbits. One representative high aspect ratio (AR-height/neck width) aneurysm and one low AR aneurysm were created at the origin of the right common carotid artery in two New Zealand white rabbits. Three-dimensional (3D) reconstructions of the aneurysm and surrounding arteries were created using 3D rotational angiographic data. Five models with varying extents of neighboring vasculature were created for both the high and low AR cases. A reference model included the aneurysm sac, left common carotid artery (LCCA), aortic arch, and downstream trifurcation/quadrification. Three-dimensional, pulsatile CFD studies were performed and streamlines, wall shear stress (WSS), oscillatory shear index, and cross sectional velocity were compared between the models. The influence of the vascular domain on intra-aneurysmal hemodynamics varied between the low and high AR cases. For the high AR case, even a simple model including only the aneurysm, a small section of neighboring vasculature, and simple extensions captured the main features of the steamline and WSS distribution predicted by the reference model. However, the WSS distribution in the low AR case was more strongly influenced by the extent of vasculature. In particular, it was necessary to include the downstream quadrification and upstream LCCA to obtain good predictions of WSS. The findings in this work demonstrate the accuracy of CFD results can be compromised if insufficient neighboring vessels are included in studies of hemodynamics in elastase induced rabbit aneurysms. Consideration of aspect ratio, hemodynamic

  4. Seizure Duration and Hemodynamic State during Electroconvulsive Therapy: Sodium Thiopental versus Propofol

    PubMed Central

    Jarineshin, Hashem; Kashani, Saeed; Fekrat, Fereydoon; Vatankhah, Majid; Golmirzaei, Javad; Alimolaee, Esmaeel; Zafarpour, Hamid

    2016-01-01

    Introduction: General anesthesia is required for Electroconvulsive Therapy (ECT) and it is usually provided by a hypnotic agent. The seizure duration is important for the treatment, and it is usually accompanied by severe hemodynamic changes. The aim of this study was to compare the effects of sodium thiopental versus Propofol on seizure duration and hemodynamic variables during ECT. Methods: A number of 100 patient-sessions of ECT were included in this randomized clinical trial. The initial hemodynamic state of each patient was recorded. Anesthesia was induced by Sodium thiopental in the 1st group and with Propofol in 2nd group. All the patients received the muscle relaxant succinylcholine. The hemodynamic variables after seizure and seizure duration were recorded. The data were analyzed through SPSS 20 and independent t-test. P<0.05 was considered significant. Results: The mean duration of seizure in the sodium thiopental group was significantly longer than the Propofol group (40.3±16.6 sec versus 32±11.3 sec) (P=0.001). There was no statistically significant difference between the mean energy level applied in the two groups (20.5±3.81 joules in the sodium thiopental versus 20.2±3.49 joules in the Propofol group). The mean systolic and diastolic blood pressure at all times after seizure and mean heart rate at 3 and 5 minutes after seizure were significantly lower in Propofol than sodium thiopental groups. Discussion and Conclusion: Propofol provides a more stable hemodynamic state for the ECT procedures, and its use is highly preferred over sodium thiopental in patients with cardiovascular disease. PMID:26383207

  5. Hemodynamic and morphological characteristics of unruptured posterior communicating artery aneurysms with oculomotor nerve palsy.

    PubMed

    Lv, Nan; Yu, Ying; Xu, Jinyu; Karmonik, Christof; Liu, Jianmin; Huang, Qinghai

    2016-08-01

    OBJECT Unruptured posterior communicating artery (PCoA) aneurysms with oculomotor nerve palsy (ONP) have a very high risk of rupture. This study investigated the hemodynamic and morphological characteristics of intracranial aneurysms with high rupture risk by analyzing PCoA aneurysms with ONP. METHODS Fourteen unruptured PCoA aneurysms with ONP, 33 ruptured PCoA aneurysms, and 21 asymptomatic unruptured PCoA aneurysms were included in this study. The clinical, morphological, and hemodynamic characteristics were compared among the different groups. RESULTS The clinical characteristics did not differ among the 3 groups (p > 0.05), whereas the morphological and hemodynamic analyses showed that size, aspect ratio, size ratio, undulation index, nonsphericity index, ellipticity index, normalized wall shear stress (WSS), and percentage of low WSS area differed significantly (p < 0.05) among the 3 groups. Furthermore, multiple comparisons revealed that these parameters differed significantly between the ONP group and the asymptomatic unruptured group and between the ruptured group and the asymptomatic unruptured group, except for size, which differed significantly only between the ONP group and the asymptomatic unruptured group (p = 0.0005). No morphological or hemodynamic parameters differed between the ONP group and the ruptured group. CONCLUSIONS Unruptured PCoA aneurysms with ONP demonstrated a distinctive morphological-hemodynamic pattern that was significantly different compared with asymptomatic unruptured PCoA aneurysms and was similar to ruptured PCoA aneurysms. The larger size, more irregular shape, and lower WSS might be related to the high rupture risk of PCoA aneurysms.

  6. Oral Contraceptive Use, Muscle Sympathetic Nerve Activity, and Systemic Hemodynamics in Young Women.

    PubMed

    Harvey, Ronee E; Hart, Emma C; Charkoudian, Nisha; Curry, Timothy B; Carter, Jason R; Fu, Qi; Minson, Christopher T; Joyner, Michael J; Barnes, Jill N

    2015-09-01

    Endogenous female sex hormones influence muscle sympathetic nerve activity (MSNA), a regulator of arterial blood pressure and important factor in hypertension development. Although ≈80% of American women report using hormonal contraceptives sometime during their life, the influence of combined oral contraceptives (OCs) on MSNA and systemic hemodynamics remains equivocal. The goal of this study was to determine whether women taking OCs have altered MSNA and hemodynamics (cardiac output and total peripheral resistance) at rest during the placebo phase of OC use compared with women with natural menstrual cycles during the early follicular phase. We retrospectively analyzed data from studies in which healthy, premenopausal women (aged 18-35 years) participated. We collected MSNA values at rest and hemodynamic measurements in women taking OCs (n=53; 25±4 years) and women with natural menstrual cycles (n=74; 25±4 years). Blood pressure was higher in women taking OCs versus those with natural menstrual cycles (mean arterial pressure, 89±1 versus 85±1 mm Hg, respectively; P=0.01), although MSNA was similar in both groups (MSNA burst incidence, 16±1 versus 18±1 bursts/100 heartbeats, respectively; P=0.19). In a subset of women in which detailed hemodynamic data were available, those taking OCs (n=33) had similar cardiac output (4.9±0.2 versus 4.7±0.2 L/min, respectively; P=0.47) and total peripheral resistance (19.2±0.8 versus 20.0±0.9 U, respectively; P=0.51) as women with natural menstrual cycles (n=22). In conclusion, women taking OCs have higher resting blood pressure and similar MSNA and hemodynamics during the placebo phase of OC use when compared with naturally menstruating women in the early follicular phase. PMID:26101348

  7. The impact of hemodynamic stress on sensory signal processing in the rodent lateral geniculate nucleus

    PubMed Central

    Zitnik, Gerard A.; Clark, Brain D.; Waterhouse, Barry D.

    2013-01-01

    Hemodynamic stress via hypotensive challenge has been shown previously to cause a corticotropin-releasing factor (CRF)-mediated increase in tonic locus coeruleus (LC) activity and consequent release of norepinephrine (NE) in noradrenergic terminal fields. Although alterations in LC-NE can modulate the responsiveness of signal processing neurons along sensory pathways, little is understood regarding how continuous CRF-mediated activation of LC-NE output due to physiologically relevant stressor affects downstream target cell physiology. The goal of the present study was to investigate the effects of a physiological stressor [hemodynamic stress via sodium nitroprusside (SNP) i.v.] on stimulus evoked responses of sensory processing neurons that receive LC inputs. In rat, the dorsal lateral geniculate nucleus (dLGN) of the thalamus is the primary relay for visual information and is a major target of the LC-NE system. We used extracellular recording techniques in the anesthetized rat monitor single dLGN neuron activity during repeated presentation of light stimuli before and during hemodynamic stress. A significant decrease in magnitude occurred, as well as an increase in latency of dLGN stimulus-evoked responses were observed during hemodynamic stress. In another group of animals the CRF antagonist DpheCRF12–41 was infused onto the ipsilateral LC prior to SNP administration. This infusion blocked the hypotension-induced changes in dLGN stimulus-evoked discharge. These results show that CRF-mediated increases in LC-NE due to hemodynamic stress disrupts the transmission of information along thalamic-sensory pathways by: (1) initially reducing signal transmission during onset of the stressor and (2) decreasing the speed of stimulus evoked sensory transmission. PMID:23643838

  8. Arterial wall degeneration plus hemodynamic insult cause arterial wall remodeling and nascent aneurysm formation at specific sites in dogs.

    PubMed

    Zhu, Yue-Qi; Li, Ming-Hua; Yan, Lei; Tan, Hua-Qiao; Cheng, Ying-Sheng

    2014-09-01

    To determine whether arterial wall degeneration, in combination with hemodynamic insult, causes cerebral artery aneurysms in a dog model, we simulated the geometry and hemodynamics of a human artery by surgical reconstruction of both common carotid arteries in 12 dogs. The dogs were then randomly assigned to one of the following groups: hemodynamic insult + elastase insult group ( n = 6), hemodynamic insult group (n = 6), or elastase control group (n = 3), in which the straight common carotid arteries were subjected to elastase alone. Angiography and hemodynamic analysis were performed immediately and at 12 weeks after surgery; the animals were then killed for histologic evaluation. The 12 surgically reconstructed distal internal carotid arteries simulated the human artery well with respect to geometric and hemodynamic measurements, with the intended aneurysm sites exposed to higher wall shear stress and velocity, lower pressure, turbulent flow, and changes in wall shear stress gradient. Nascent aneurysms developed in 4 hemodynamic insult + elastase insult group dogs at 12 weeks; blood flow analysis demonstrated decreased wall shear stress, increased pressure, and wall shear stress gradient from the neck to the dome. Arterial wall remodeling or nascent aneurysm formation in the hemodynamic insult + elastase insult group versus the other groups was indicated by internal elastic lamina/elastic fiber disruption, muscular layer thinning, increased smooth muscle cell proliferation, macrophage infiltration, and high expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 in the media. These data suggest that nascent aneurysms were caused by the combination of arterial wall degeneration and hemodynamic perturbations in this distal internal carotid artery dog model.

  9. Developmental Purposes of Commercial Games.

    ERIC Educational Resources Information Center

    Practical Pointers, 1977

    1977-01-01

    Listed are 45 table, target, manipulative, active, and creative games with such developmental purposes as associative learning, tactile discrimination, and visual motor integration. Information includes the name of the item, distributor, price, description, and developmental purpose. (JYC)

  10. [The use of lithium electrophoresis combined with balneotherapy in hypertension depending on the type of central hemodynamics].

    PubMed

    Stefanchuk, L V; Parkhomenko, O A; Usenko, L I; Voronina, E V; Mamontova, L A; Morozov, A I

    1992-01-01

    Central chest rheography was used to study the central hemodynamics in 62 patients with hypertensive disease (grades I-II) before and after treatment. 23 patients (hyperkinetic hemodynamics) were treated with oxygen baths and endonasal lithium chloride electrophoresis; 20 with en--and hypokinetic types of hemodynamics received CO2 baths and endonasal lithium chloride electrophoresis. It is concluded that lithium chloride electrophoresis in association with balneotherapy increases the therapeutic effect in hypertensive disease, especially in patients with the hyperkinetic type of blood circulation. PMID:1337959

  11. Attenuation of Hemodynamic Responses to Laryngoscopy and Tracheal Intubation: Propacetamol versus Lidocaine—A Randomized Clinical Trial

    PubMed Central

    Kord Valeshabad, Ali; Nabavian, Omid; Nourijelyani, Keramat; Kord, Hadi; Vafainejad, Hossein; Kord Valeshabad, Reza; Reza Feili, Ali; Rezaei, Mehdi; Darabi, Hamed; Koohkan, Mohammad; Golbinimofrad, Poorya; Jafari, Samira

    2014-01-01

    The purpose of this study is to assess the effects of propacetamol on attenuating hemodynamic responses subsequent laryngoscopy and tracheal intubation compared to lidocaine. In this randomized clinical trial, 62 patients with the American Anesthesiologists Society (ASA) class I/II who required laryngoscopy and tracheal intubation for elective surgery were assigned to receive propacetamol 2 g/I.V./infusion (group P) or lidocaine 1.5 mg/kg (group L) prior to laryngoscopy. Systolic and diastolic blood pressures (SBP, DBP), mean arterial pressure (MAP), and heart rate (HR) were recorded at baseline, before laryngoscopy and within nine minutes after intubation. In both groups P and L, MAP increased after laryngoscopy and the changes were statistically significant (P < 0.001). There were significant changes of HR in both groups after intubation (P < 0.02), but the trend of changes was different between two groups (P < 0.001). In group L, HR increased after intubation and its change was statistically significant within 9 minutes after intubation (P < 0.001), while in group P, HR remained stable after intubation (P = 0.8). Propacetamol 2 gr one hour prior intubation attenuates heart rate responses after laryngoscopy but is not effective to prevent acute alterations in blood pressure after intubation. PMID:24822063

  12. Attenuation of Hemodynamic Responses to Laryngoscopy and Tracheal Intubation: Propacetamol versus Lidocaine-A Randomized Clinical Trial.

    PubMed

    Kord Valeshabad, Ali; Nabavian, Omid; Nourijelyani, Keramat; Kord, Hadi; Vafainejad, Hossein; Kord Valeshabad, Reza; Reza Feili, Ali; Rezaei, Mehdi; Darabi, Hamed; Koohkan, Mohammad; Golbinimofrad, Poorya; Jafari, Samira

    2014-01-01

    The purpose of this study is to assess the effects of propacetamol on attenuating hemodynamic responses subsequent laryngoscopy and tracheal intubation compared to lidocaine. In this randomized clinical trial, 62 patients with the American Anesthesiologists Society (ASA) class I/II who required laryngoscopy and tracheal intubation for elective surgery were assigned to receive propacetamol 2 g/I.V./infusion (group P) or lidocaine 1.5 mg/kg (group L) prior to laryngoscopy. Systolic and diastolic blood pressures (SBP, DBP), mean arterial pressure (MAP), and heart rate (HR) were recorded at baseline, before laryngoscopy and within nine minutes after intubation. In both groups P and L, MAP increased after laryngoscopy and the changes were statistically significant (P < 0.001). There were significant changes of HR in both groups after intubation (P < 0.02), but the trend of changes was different between two groups (P < 0.001). In group L, HR increased after intubation and its change was statistically significant within 9 minutes after intubation (P < 0.001), while in group P, HR remained stable after intubation (P = 0.8). Propacetamol 2 gr one hour prior intubation attenuates heart rate responses after laryngoscopy but is not effective to prevent acute alterations in blood pressure after intubation. PMID:24822063

  13. Evaluation of Hemodynamic Properties of Cerebral Venous Drainage in Patients with Multiple Sclerosis: A Case-Control Study

    PubMed Central

    Jandaghi, Ali Babaei; Amanian, Dayan; Roudbari, Seyed Ali; Kanafi, Alireza Rajabzadeh; Pourghorban, Ramin

    2014-01-01

    Summary Background The purpose of this study was to compare patients with multiple sclerosis and healthy control subjects as regards hemodynamics of cerebral venous drainage. Material/Methods Between December 2012 and May 2013, 44 consecutive patients with multiple sclerosis and 44 age- and sex-matched healthy subjects underwent the B-mode, color Doppler, and duplex Doppler evaluations of the internal jugular vein (IJV) and vertebral vein. The following four parameters were investigated: IJV stenosis, reversal of postural control of the cerebral venous outflow pathways, absence of detectable blood flow in the IJVs and/or vertebral veins, and reflux in the IJVs and/or vertebral veins in the sitting or supine position. Results In the study group, IJV stenosis, postural control reversal of the cerebral venous outflow pathways, and absence of flow in the IJVs and/or vertebral veins were found in 3 (6.8%), 2 (4.5%), and 3 (6.8%) patients, respectively. In the control group, IJV stenosis (P=0.12), postural control reversal of the cerebral venous outflow pathways (P=0.50), and absence of flow (P=0.12) were not detected. Abnormal reflux was found neither in multiple sclerosis patients nor in healthy subjects. Conclusions No significant difference in the cerebral venous drainage through the IJV or vertebral vein was found between patients with multiple sclerosis and healthy subjects within any of the investigated ultrasonographic parameters. PMID:25250100

  14. The acute effects of the thermogenic supplement Meltdown on energy expenditure, fat oxidation, and hemodynamic responses in young, healthy males

    PubMed Central

    Jitomir, Jean; Nassar, Erika; Culbertson, Julie; Moreillon, Jen; Buford, Thomas; Hudson, Geoffrey; Cooke, Matt; Kreider, Richard; Willoughby, Darryn S

    2008-01-01

    The purpose of this study was to evaluate the effects of a thermogenic supplement, Meltdown, on energy expenditure, fat oxidation, and hemodynamics before and after maximal treadmill exercise. In a double-blind, randomized, placebo-controlled, cross-over design, 12 male participants underwent two testing sessions after consuming either the Meltdown or placebo supplement. While in a fasted state, participants rested for one hour, orally ingested either Meltdown or placebo and rested for another hour, performed a maximal treadmill exercise test, and then rested for another hour. Throughout the testing protocol, resting energy expenditure (REE) and respiratory exchange ratio (RER) were assessed. In addition, heart rate (HR) and blood pressure (BP) were assessed before and after exercise. Meltdown increased REE significantly more than placebo at 45 min (1.44 ± 0.25 vs. 1.28 ± 0.23 kcal/min; p = 0.003), 60 min (1.49 ± 0.28 vs. 1.30 ± 0.22 kcal/min; p = 0.025), and 120 min (1.51 ± 0.26 vs. 1.33 ± 0.27 kcals/min; p = 0.014) post-ingestion. Meltdown significantly decreased RER at 30 min (0.84 ± 0.03 vs. 0.91 ± 0.04; p = 0.022) and 45 min post-ingestion (0.82 ± 0.04 vs. 0.89 ± 0.05; p = 0.042), and immediately post-exercise (0.83 ± 0.05 vs. 0.90 ± 0.07; p = 0.009). Furthermore, over the course of the evaluation period, area under the curve assessment demonstrated that REE was significantly increased with Meltdown compared to placebo (992.5 ± 133.1 vs. 895.1 ± 296.1 kcals; p = 0.043), while RER was significantly less than placebo (5.55 ± 0.61 vs. 5.89 ± 0.44; p = 0.002) following ingestion. HR and BP were not significantly affected prior to exercise with either supplement (p > 0.05) and the exercise-induced increases for HR and BP decreased into recovery and were not different between supplements (p > 0.05). These data suggest that Meltdown enhances REE and fat oxidation more than placebo for several hours after ingestion in fully rested and post

  15. Transoesophageal Doppler compared to central venous pressure for perioperative hemodynamic monitoring and fluid guidance in liver resection

    PubMed Central

    El Sharkawy, Osama A.; Refaat, Emad K.; Ibraheem, Abdel Elmoniem M.; Mahdy, Wafiya R.; Fayed, Nirmeen A.; Mourad, Wesam S.; Abd Elhafez, Hanaa S.; Yassen, Khaled A.

    2013-01-01

    Purpose: Major hepatic resections may result in hemodynamic changes. Aim is to study transesophageal Doppler (TED) monitoring and fluid management in comparison to central venous pressure (CVP) monitoring. A follow-up comparative hospital based study. Methods: 59 consecutive cirrhotic patients (CHILD A) undergoing major hepatotomy. CVP monitoring only (CVP group), (n=30) and TED (Doppler group), (n=29) with CVP transduced but not available on the monitor. Exclusion criteria include contra-indication for Doppler probe insertion or bleeding tendency. An attempt to reduce CVP during the resection in both groups with colloid restriction, but crystalloids infusion of 6 ml/kg/h was allowed to replace insensible loss. Post-resection colloids infusion were CVP guided in CVP group (5-10 mmHg) and corrected flow time (FTc) aortic guided in Doppler group (>0.4 s) blood products given according to the laboratory data. Results: Using the FTc to guide Hydroxyethyl starch 130/0.4 significantly decreased intake in TED versus CVP (1.03 [0.49] versus 1.74 [0.41] Liter; P<0.05). Nausea, vomiting, and chest infection were less in TED with a shorter hospital stay (P<0.05). No correlation between FTc and CVP (r=0.24, P > 0.05). Cardiac index and stroke volume of TED increased post-resection compared to baseline, 3.0 (0.9) versus 3.6 (0.9) L/min/m2, P<0.05; 67.1 (14.5) versus 76 (13.2) ml, P<0.05, respectively, associated with a decrease in systemic vascular resistance (SVR) 1142.7 (511) versus 835.4 (190.9) dynes.s/cm5, P<0.05. No significant difference in arterial pressure and CVP between groups at any stage. CVP during resection in TED 6.4 (3.06) mmHg versus 6.1 (1.4) in CVP group, P=0.6. TED placement consumed less time than CVP (7.3 [1.5] min versus 13.2 [2.9], P<0.05). Conclusion: TED in comparison to the CVP monitoring was able to reduced colloids administration post-resection, lower morbidity and shorten hospital stay. TED consumed less time to insert and was also able to present

  16. Acute impact of intermittent pneumatic leg compression frequency on limb hemodynamics, vascular function, and skeletal muscle gene expression in humans.

    PubMed

    Sheldon, Ryan D; Roseguini, Bruno T; Thyfault, John P; Crist, Brett D; Laughlin, M H; Newcomer, Sean C

    2012-06-01

    The mechanisms by which intermittent pneumatic leg compression (IPC) treatment effectively treats symptoms associated with peripheral artery disease remain speculative. With the aim of gaining mechanistic insight into IPC treatment, the purpose of this study was to investigate the effect of IPC frequency on limb hemodynamics, vascular function, and skeletal muscle gene expression. In this two study investigation, healthy male subjects underwent an hour of either high-frequency (HF; 2-s inflation/3-s deflation) or low-frequency (LF; 4-s inflation/16-s deflation) IPC treatment of the foot and calf. In study 1 (n = 11; 23.5 ± 4.7 yr), subjects underwent both HF and LF treatment on separate days. Doppler/ultrasonography was used to measure popliteal artery diameter and blood velocity at baseline and during IPC treatment. Flow-mediated dilation (FMD) and peak reactive hyperemia blood flow (RHBF) were determined before and after IPC treatment. In study 2 (n = 19; 22.0 ± 4.6 yr), skeletal muscle biopsies were taken from the lateral gastrocnemius of the treated and control limb at baseline and at 30- and 150-min posttreatment. Quantitative PCR was used to assess mRNA concentrations of genes associated with inflammation and vascular remodeling. No treatment effect on vascular function was observed. Cuff deflation resulted in increased blood flow (BF) and shear rate (SR) in both treatments at the onset of treatment compared with baseline (P < 0.01). BF and SR significantly diminished by 45 min of HF treatment only (P < 0.01). Both treatments reduced BF and SR and elevated oscillatory shear index compared with baseline (P < 0.01) during cuff inflation. IPC decreased the mRNA expression of cysteine-rich protein 61 from baseline and controls (P <0 .01) and connective tissue growth factor from baseline (P < 0.05) in a frequency-dependent manner. In conclusion, a single session of IPC acutely impacts limb hemodynamics and skeletal muscle gene expression in a frequency

  17. A Shape Memory Polymer Dialysis Needle Adapter for the Reduction of Hemodynamic Stress within Arteriovenous Grafts

    SciTech Connect

    Ortega, J M; Small, W; Wilson, T S; Benett, W; Loge, J; Maitland, D J

    2006-08-16

    A deployable, shape memory polymer adapter is investigated for reducing the hemodynamic stress caused by a dialysis needle flow within an arteriovenous graft. Computational fluid dynamics simulations of dialysis sessions with and without the adapter demonstrate that the adapter provides a significant decrease in the wall shear stress. In vitro flow visualization measurements are made within a graft model following delivery and actuation of a prototype shape memory polymer adapter. Vascular access complications resulting from arteriovenous (AV) graft failures account for over $1 billion per year in the health care costs of dialysis patients in the U.S.[1] The primary mode of failure of arteriovenous fistulas (AVF's) and polytetrafluoroethylene (PTFE) grafts is the development of intimal hyperplasia (IH) and the subsequent formation of stenotic lesions, resulting in a graft flow decline. The hemodynamic stresses arising within AVF's and PTFE grafts play an important role in the pathogenesis of IH. Studies have shown that vascular damage can occur in regions where there is flow separation, oscillation, or extreme values of wall shear stress (WSS).[2] Nevaril et al.[3] show that exposure of red blood cells to WSS's on the order of 1500 dynes/cm2 can result in hemolysis. Hemodynamic stress from dialysis needle flow has recently been investigated for the role it plays in graft failure. Using laser Doppler velocimetry measurements, Unnikrishnan et al.[4] show that turbulence intensities are 5-6 times greater in the AV flow when the needle flow is present and that increased levels of turbulence exist for approximately 7-8cm downstream of the needle. Since the AVF or PTFE graft is exposed to these high levels of hemodynamic stress several hours each week during dialysis sessions, it is quite possible that needle flow is an important contributor to vascular access occlusion.[4] We present a method for reducing the hemodynamic stress in an AV graft by tailoring the fluid

  18. Effects of the inlet conditions and blood models on accurate prediction of hemodynamics in the stented coronary arteries

    NASA Astrophysics Data System (ADS)

    Jiang, Yongfei; Zhang, Jun; Zhao, Wanhua

    2015-05-01

    Hemodynamics altered by stent implantation is well-known to be closely related to in-stent restenosis. Computational fluid dynamics (CFD) method has been used to investigate the hemodynamics in stented arteries in detail and help to analyze the performances of stents. In this study, blood models with Newtonian or non-Newtonian properties were numerically investigated for the hemodynamics at steady or pulsatile inlet conditions respectively employing CFD based on the finite volume method. The results showed that the blood model with non-Newtonian property decreased the area of low wall shear stress (WSS) compared with the blood model with Newtonian property and the magnitude of WSS varied with the magnitude and waveform of the inlet velocity. The study indicates that the inlet conditions and blood models are all important for accurately predicting the hemodynamics. This will be beneficial to estimate the performances of stents and also help clinicians to select the proper stents for the patients.

  19. Clinical Implications of Cluster Analysis-Based Classification of Acute Decompensated Heart Failure and Correlation with Bedside Hemodynamic Profiles

    PubMed Central

    Ahmad, Tariq; Desai, Nihar; Wilson, Francis; Schulte, Phillip; Dunning, Allison; Jacoby, Daniel; Allen, Larry; Fiuzat, Mona; Rogers, Joseph; Felker, G. Michael; O’Connor, Christopher; Patel, Chetan B.

    2016-01-01

    Background Classification of acute decompensated heart failure (ADHF) is based on subjective criteria that crudely capture disease heterogeneity. Improved phenotyping of the syndrome may help improve therapeutic strategies. Objective To derive cluster analysis-based groupings for patients hospitalized with ADHF, and compare their prognostic performance to hemodynamic classifications derived at the bedside. Methods We performed a cluster analysis on baseline clinical variables and PAC measurements of 172 ADHF patients from the ESCAPE trial. Employing regression techniques, we examined associations between clusters and clinically determined hemodynamic profiles (warm/cold/wet/dry). We assessed association with clinical outcomes using Cox proportional hazards models. Likelihood ratio tests were used to compare the prognostic value of cluster data to that of hemodynamic data. Results We identified four advanced HF clusters: 1) male Caucasians with ischemic cardiomyopathy, multiple comorbidities, lowest B-type natriuretic peptide (BNP) levels; 2) females with non-ischemic cardiomyopathy, few comorbidities, most favorable hemodynamics; 3) young African American males with non-ischemic cardiomyopathy, most adverse hemodynamics, advanced disease; and 4) older Caucasians with ischemic cardiomyopathy, concomitant renal insufficiency, highest BNP levels. There was no association between clusters and bedside-derived hemodynamic profiles (p = 0.70). For all adverse clinical outcomes, Cluster 4 had the highest risk, and Cluster 2, the lowest. Compared to Cluster 4, Clusters 1–3 had 45–70% lower risk of all-cause mortality. Clusters were significantly associated with clinical outcomes, whereas hemodynamic profiles were not. Conclusions By clustering patients with similar objective variables, we identified four clinically relevant phenotypes of ADHF patients, with no discernable relationship to hemodynamic profiles, but distinct associations with adverse outcomes. Our analysis

  20. Purpose Plus: Supporting Youth Purpose, Control, and Academic Achievement

    ERIC Educational Resources Information Center

    Pizzolato, Jane Elizabeth; Brown, Elizabeth Levine; Kanny, Mary Allison

    2011-01-01

    Research in the past decade suggests that a persistent achievement gap between students from low-income minority backgrounds and higher-income white backgrounds may be rooted in theories of student motivation and youth purpose. Yet limited research exists regarding the role of purpose on positive youth development as it pertains to academic…

  1. Experience of decortication for restrictive hemodynamics in adults with congenital heart disease.

    PubMed

    Mizuno, Masanori; Ohuchi, Hideo; Kagisaki, Koji; Miyazaki, Aya; Ishibashi-Ueda, Hatsue; Yamada, Osamu

    2014-08-01

    We treated four postoperative adults with congenital heart disease with severe restrictive hemodynamics (RH), and performed decortication (DC) with the anticipation of some relief of the RH. The catheterizations before DC showed high central venous, and right and left ventricular end-diastolic pressures with "dip-and-plateau" pressure waveforms in the right and left ventricles. Upon myocardial histopathologic examination, moderate myocardial fibrotic change was demonstrated in two of three cases. DC led to decrease in type B natriuretic peptide levels in all cases, resulting in a decline in the central venous, right and left ventricular end-diastolic pressures in three cases. Successful DC-related relief of RH, dilatation of the ventricles with decline in central and end-diastolic pressures, was observed in only one case. Our limited DC-related hemodynamic improvement indicates a complexity of the severe RH, which may represent a unique intractable heart failure pathophysiology in intractable postoperative adult congenital heart disease.

  2. Cardiac Hemodynamics in the Pathogenesis of Congenital Heart Disease and Aortic Valve Calcification

    NASA Astrophysics Data System (ADS)

    Nigam, Vishal

    2011-11-01

    An improved understanding of the roles of hemodynamic forces play in cardiac development and the pathogenesis of cardiac disease will have significant scientific and clinical impact. I will focus on the role of fluid dynamics in congenital heart disease and aortic valve calcification. Congenital heart defects are the most common form of birth defect. Aortic valve calcification/stenosis is the third leading cause of adult heart disease and the most common form of acquired valvular disease in developed countries. Given the high incidence of these diseases and their associated morbidity and mortality, the potential translational impact of an improved understanding of cardiac hemodynamic forces is very large. Division of Pediatric Cardiology, Rady Children's Hospital, San Diego

  3. Effect of ultra-fast mild hypothermia using total liquid ventilation on hemodynamics and respiratory mechanics.

    PubMed

    Sage, Michaël; Nadeau, Mathieu; Kohlhauer, Matthias; Praud, Jean-Paul; Tissier, Renaud; Robert, Raymond; Walti, Hervé; Micheau, Philippe

    2016-08-01

    Ultra-fast cooling for mild therapeutic hypothermia (MTH) has several potential applications, including prevention of post-cardiac arrest syndrome. Ultra-fast MTH by total liquid ventilation (TLV) entails the sudden filling of the lungs with a cold perfluorocarbon liquid and its subsequent use to perform TLV. The present physiological study was aimed at assessing whether pulmonary and systemic hemodynamics as well as lung mechanics are significantly altered during this procedure. Pulmonary and systemic arterial pressures, cardiac output as well as airway resistance and respiratory system compliance were measured during ultra-fast MTH by TLV followed by rewarming and normothermia in six healthy juvenile lambs. Results show that none of the studied variables were altered upon varying the perfluorocarbon temperature from 12 to 41 °C. It is concluded that ultra-fast MTH by TLV does not have any deleterious effect on hemodynamics or lung mechanics in healthy juvenile lambs.

  4. Ethanol consumption impairs the hemodynamic response to hemorrhagic shock in rats.

    PubMed

    Sato, Hiroaki; Tanaka, Toshiko; Kasai, Kentaro

    2013-02-01

    Alcohol intoxication can exacerbate hemodynamic instability following hemorrhagic shock. Impairment of hormonal, neurohumoral, and immune responses can contribute to such instability; however, the relationship between blood alcohol levels and the progression of hemorrhagic shock accompanied with these responses has not been clearly demonstrated. Herein, we examined this relationship in rats treated with various dose of alcohol. After oral administration of alcohol and then hemorrhage, the recovery of mean blood pressure (MBP); increase in plasma level of norepinephrine, epinephrine, and vasopressin; and survival interval decreased in a dose-dependent manner as the blood alcohol level increased. There were no significant differences in the production of proinflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β among the groups. The present results demonstrated alcohol aggravates hemorrhagic shock in a dose-dependent manner not by alerting the immune response, but by suppressing hormonal and neurohumoral responses, thereby inhibiting hemodynamic autoregulation and shortening the survival interval.

  5. Imaging of hemodynamic effects in arthritic joints with dynamic optical tomography

    NASA Astrophysics Data System (ADS)

    Hielscher, Andreas H.; Lasker, Joseph M.; Fong, Christopher J.; Dwyer, Edward

    2007-07-01

    Optical probing of hemodynamics is often employed in areas such as brain, muscular, and breast-cancer imaging. In these studies an external stimulus is applied and changes in relevant physiological parameters, e.g. oxy or deoxyhemoglobin concentrations, are determined. In this work we present the first application of this method for characterizing joint diseases, especially effects of rheumatoid arthritis (RA) in the proximal-interphalangeal (PIP) finger joints. Using a dual-wavelength tomographic imaging system together with previously implemented model-based iterative image reconstruction schemes, we have performed dynamic imaging case studies on a limited number of healthy volunteers and patients diagnosed with RA. Inflating a sphygmomanometer cuff placed around the forearm we elicited a controlled vascular response. We observed pronounced differences between the hemodynamic effect occurring in healthy volunteers and patients affected by RA.

  6. Implantable Hemodynamic Monitoring in Ambulatory Heart Failure: Who, When, Why, How?

    PubMed

    Desai, Akshay S

    2015-12-01

    Despite considerable advances in therapeutics, the risk of hospitalization for patients with heart failure remains high. Since many hospitalizations in heart failure patients are driven by congestive exacerbations, optimal management of congestion is a key goal of longitudinal heart failure disease management. Existing strategies for hemodynamic optimization in heart failure patients rely heavily on remote monitoring of weights and symptoms, augmented in selected cases by data from implanted cardiac devices. When they have been systematically studied, however, none of these approaches has been demonstrated to consistently improve clinical outcomes. Recent data suggests that implantable hemodynamic monitors may facilitate early detection and treatment of worsening congestion, thereby reducing the need for hospital admission. In this review, we explore the rationale and evidence supporting the use of these novel devices as an adjunct to routine heart failure management and the strategies for appropriate patient selection.

  7. Influence of Exercise Modality on Cerebral-Ocular Hemodynamics and Pressures

    NASA Technical Reports Server (NTRS)

    Crowell, Brent; Martin, David; Goetchius, Elizabeth; Gonzales, Rebecca; Matz, Timothy; Ploutz-Snyder, Robert; Stenger, Michael; Ploutz-Snyder, Lori; Scott, Jessica

    2016-01-01

    Introduction: (a) Exercise training is beneficial for cardiac, muscle, and bone health, however, its effects on the development of visual impairment due to intracranial pressure (VIIP) remain controversial, (b) Resistive exercise without a Valsalva has been shown to increase intracranial pressure (ICP) by 3 mmHg, while with a Valsalva the increase is 18 mmHg, (c) Similar increases in intraocular pressure (IOP) have been observed during weight lifting, (d) Aerobic exercise also induces hemodynamic changes that impact ICP and IOP. During moderate-intensity exercise increases in cerebral blood flow and velocity occur, suggesting that moderate-intensity exercise could further increase intracranial blood volume and therefore ICP; and (e) Importantly, however, it is unknown how regional differences in cerebrovascular hemodynamics impact ocular pressure and global cerebral inflow and outflow during exercise with a cephalad fluid shift.

  8. Lattice Boltzmann method simulating hemodynamics in the three-dimensional stenosed and recanalized human carotid bifurcations

    NASA Astrophysics Data System (ADS)

    Kang, XiuYing

    2015-01-01

    By using the lattice Boltzmann method (LBM) pulsatile blood flows were simulated in three-dimensional moderate stenosed and recanalized carotid bifurcations to understand local hemodynamics and its relevance in arterial atherosclerosis formation and progression. The helical flow patterns, secondary flow and wall dynamical pressure spatiotemporal distributions were investigated, which leads to the disturbed shear forces in the carotid artery bifurcations. The wall shear stress distributions indicated by time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and the relative residence time (RRT) in a cardiac cycle revealed the regions where atherosclerotic plaques are prone to form, extend or rupture. This study also illustrates the point that locally disturbed flow may be considered as an indicator for early atherosclerosis diagnosis. Additionally the present work demonstrates the robust and highly efficient advantages of the LBM for the hemodynamics study of the human blood vessel system.

  9. Imaging hemodynamic response after ischemic stroke in mouse cortex using visible-light optical coherence tomography

    PubMed Central

    Chen, Siyu; Liu, Qi; Shu, Xiao; Soetikno, Brian; Tong, Shanbao; Zhang, Hao F.

    2016-01-01

    Visible-light optical coherence tomography (Vis-OCT) is an emerging technology that can image hemodynamic response in microvasculature. Vis-OCT can retrieve blood oxygen saturation (sO2) mapping using intrinsic optical absorption contrast while providing high-resolution anatomical vascular structures at the same time. To improve the accuracy of Vis-OCT oximetry on vessels embedded in highly scattering medium, i.e., brain cortex, we developed and formulated a novel dual-depth sampling and normalization strategy that allowed us to minimize the detrimental effect of ubiquitous tissue scattering. We applied our newly developed approach to monitor the hemodynamic response in mouse cortex after focal photothrombosis. We observed vessel dilatation, which was negatively correlated with the original vessel diameter, in the penumbra region. The sO2 of vessels in the penumbra region also dropped below normal range after focal ischemia.

  10. Relationship of bispectral index to hemodynamic variables and alveolar concentration multiples of sevoflurane in puppies.

    PubMed

    Morgaz, J; Granados, M M; Domínguez, J M; Navarrete, R; Galán, A; Fernández, J A; Gómez-Villamandos, R J

    2009-06-01

    The relationships between bispectral index (BIS), cardiovascular variables and minimum alveolar concentration (MAC) multiples of sevoflurane in puppies were determined. Five puppies were anesthetized with sevoflurane on two occasions. First, the individual sevoflurane MAC values were determined for each puppy. Secondly, dogs were anesthetized with sevoflurane at each of 5 MAC multiples, 0.75, 1, 1.25, 1.5 and 1.75 MAC administered in random order. Hemodynamic parameters and BIS data were collected for 20min. Somatic stimulus was then applied and the same parameters and data were collected for 6min. Correlation between BIS and end tidal sevoflurane and between BIS and hemodynamic parameters were studied. We found positive significant correlation in both cases. BIS is lower in puppies that in adults at the same alveolar anesthetic concentrations and sevoflurane appears to be a safe anesthetic in puppies.

  11. Using ventilator and cardiovascular graphics in the patient who is hemodynamically unstable.

    PubMed

    Murphy, Bryant A; Durbin, Charles G

    2005-02-01

    The interaction of a mechanical ventilator and the human cardiovascular system is complex. One of the most important effects of positive-pressure ventilation (PPV) is that it can decrease venous return. PPV also alters right- and left-ventricular ejection. Increased lung volume increases right-ventricular size by increasing pulmonary vascular resistance, causing intraventricular cardiac-septum shift, and decreasing left-ventricular filling. Increased intrathoracic pressure reduces afterload on the LV and increases ejection of blood from the LV. Understanding and managing these complex and often opposing interactions in critically ill patients is facilitated by analysis of hemodynamic and ventilator waveforms at the bedside. The relationship of PPV to changes in the arterial pressure waveform gives important information regarding appropriate fluid and vasopressor treatment. This article focuses on effects of respiratory pressures on hemodynamics and considers how cardiac pressures can be transmitted to the airway and cause ventilator malfunction. PMID:15691395

  12. A practical introduction to the hemodynamic analysis of the cardiovascular system with 4D Flow MRI.

    PubMed

    Pineda Zapata, J A; Delgado de Bedout, J A; Rascovsky Ramírez, S; Bustamante, C; Mesa, S; Calvo Betancur, V D

    2014-01-01

    The 4D Flow MRI technique provides a three-dimensional representation of blood flow over time, making it possible to evaluate the hemodynamics of the cardiovascular system both qualitatively and quantitatively. In this article, we describe the application of the 4D Flow technique in a 3T scanner; in addition to the technical parameters, we discuss the advantages and limitations of the technique and its possible clinical applications. We used 4D Flow MRI to study different body areas (chest, abdomen, neck, and head) in 10 volunteers. We obtained 3D representations of the patterns of flow and quantitative hemodynamic measurements. The technique makes it possible to evaluate the pattern of blood flow in large and midsize vessels without the need for exogenous contrast agents.

  13. In vivo imaging of retinal hemodynamics with OCT angiography and Doppler OCT

    PubMed Central

    Huang, Shenghai; Shen, Meixiao; Zhu, Dexi; Chen, Qi; Shi, Ce; Chen, Zhongping; Lu, Fan

    2016-01-01

    Retinal hemodynamics is important for early diagnosis and precise monitoring in retinal vascular diseases. We propose a novel method for measuring absolute retinal blood flow in vivo using the combined techniques of optical coherence tomography (OCT) angiography and Doppler OCT. Doppler values can be corrected by Doppler angles extracted from OCT angiography images. A three-dimensional (3D) segmentation algorithm based on dynamic programming was developed to extract the 3D boundaries of optic disc vessels, and Doppler angles were calculated from 3D vessel geometry. The accuracy of blood flow from the Doppler OCT was validated using a flow phantom. The feasibility of the method was tested on a subject in vivo. The pulsatile retinal blood flow and the parameters for retinal hemodynamics were successfully obtained. PMID:26977370

  14. Stentless bioprosthesis provided excellent hemodynamic performance in a military scuba diver with infective endocarditis.

    PubMed

    Dumantepe, Mert; Gullu, A Umit; Komurcu, Gurkan; Inan, Kaan; Yilmaz, A Turan

    2009-07-01

    Infective endocarditis is a diagnostic and therapeutic challenge that ultimately requires surgical intervention in 20% of all cases. Surgical treatment of active infective endocarditis requires not only hemodynamic repair, but also special emphasis on the eradiation of the infectious focus to prevent recurrence. This goal can be achieved by the combination of aggressive debridement of infective tissue and appropriate and adequate antibiotic treatment. We report a case of Streptococcus viridans induced aortic valve perforation related to aortic valve and root endocarditis, which was successfully treated with aortic root replacement using stentless bioprosthesis. This bioprosthesis thus seems to be a valuable option for active endocarditis, provides excellent hemodynamics with low gradients. Acceptable operative risk can be achieved by full root stentless valve replacement in physically active patients such as divers.

  15. A numerical study on the effect of hematocrit on hemodynamic characteristics in arteriovenous graft

    NASA Astrophysics Data System (ADS)

    Kim, Ji Tae; Sung, Kun Hyuk; Ryou, Hong Sun

    2014-08-01

    Stenosis at an arteriovenous graft is related with the critical ranges of hemodynamic characteristics. Hematocrit has a significant effect on the blood viscosity. During hemodialysis, hematocrit is changed by the dialysis machine. The effect of hematocrit on hemodynamic characteristics is investigated by numerical study. A multiphase non-Newtonian blood model was used to analyze the changes of hematocrit. The hematocrit of blood flows at injection needle changed 40%, 50%, and 60%. As a result, the blood viscosity increased by about 6% point. Also, the high wall shear stress region (over 3 Pa) increased about 6% point when the hematocrit at the vein anastomosis increased by about 2% point. When the hematocrit increased by 4% at the vein anastomosis, an extremely high wall shear stress region (over 7.5 Pa) increased by 3 times. Thus, the variation of hematocrit should be predicted using a multiphase blood model to avoid the critical range of wall shear stress when hematocrit changes regionally.

  16. Hemodynamic responses to seated and supine lower body negative pressure - Comparison with +Gz acceleration

    NASA Technical Reports Server (NTRS)

    Polese, Alvese; Sandler, Harold; Montgomery, Leslie D.

    1992-01-01

    The hemodynamic responses to LBNP in seated subjects and in subjects in supine body positions were compared and were correlated with hemodynamic changes which occurred during a simulated (by centrifugation) Shuttle reentry acceleration with a slow onset rate of 0.002 G/s and during gradual onset exposures to +3 Gz and +4 Gz. Results demonstrate that seated LBNP at a level of -40 mm Hg can serve as a static simulator for changes in the heart rate and in mean blood pressure induced by gradual onset acceleration stress occurring during Shuttle reentry. The findings also provide a rationale for using LBNP during weightlessness as a means of imposing G-loading on the circulation prior to reentry.

  17. Hemodynamic and neurohormonal responses to extreme orthostatic stress in physically fit young adults

    NASA Astrophysics Data System (ADS)

    Grasser, E. K.; Goswami, N.; Rössler, A.; Vrecko, K.; Hinghofer-Szalkay, H.

    2009-04-01

    Blood pressure stability may be jeopardized in astronauts experiencing orthostatic stress. There is disagreement about cardiovascular and endocrine stress responses that emerge when a critical (presyncopal) state is reached. We studied hemodynamic and neurohormonal changes as induced by an orthostatic stress paradigm (head-up tilt combined with lower body negative pressure) that leads to a syncopal endpoint. From supine control to presyncope, heart rate increased by 78% and thoracic impedance by 12%. There was a 49% fall in stroke volume index, 19% in mean arterial blood pressure, 14% in total peripheral resistance index and 11% in plasma volume. Plasma norepinephrine rose by 107, epinephrine by 491, plasma renin activity by 167, and cortisol by 25%. Hemodynamic and hormonal changes of clearly different magnitude emerge in presyncope as compared to supine rest. Additional studies are warranted to reveal the exact time course of orthostatic changes up to syncopal levels.

  18. Hemodynamic correlates of visuomotor motor adaptation by functional Near Infrared Spectroscopy.

    PubMed

    Gentili, Rodolphe J; Hadavi, Cyrus; Ayaz, Hasan; Shewokis, Patricia A; Contreras-Vidal, Jose L

    2010-01-01

    The development of rehabilitation engineering technologies such as the design of smart prosthetics necessitates a deep understanding of brain mechanisms engaged in ecological situations when human interact with new tools and/or environments. Thus, we aimed to investigate potential hemodynamic signatures reflecting the level of cognitive-motor performance and/or the internal or mental states of individuals when learning a novel tool with unknown properties. These markers were derived from functional Near Infrared Spectroscopy (fNIR) signals. Our results indicate an increased level of oxy-hemoglobin in prefrontal sensors associated with enhanced kinematics during early compared with late learning. This is consistent with previous neuroimaging studies that revealed a higher contribution of prefrontal areas during early compare to late adaptation learning. These non-invasive functional hemodynamic markers may play a role in bioengineering applications such as smart neuroprosthesis and brain monitoring where adaptive behavior is important.

  19. Imaging hemodynamic response after ischemic stroke in mouse cortex using visible-light optical coherence tomography

    PubMed Central

    Chen, Siyu; Liu, Qi; Shu, Xiao; Soetikno, Brian; Tong, Shanbao; Zhang, Hao F.

    2016-01-01

    Visible-light optical coherence tomography (Vis-OCT) is an emerging technology that can image hemodynamic response in microvasculature. Vis-OCT can retrieve blood oxygen saturation (sO2) mapping using intrinsic optical absorption contrast while providing high-resolution anatomical vascular structures at the same time. To improve the accuracy of Vis-OCT oximetry on vessels embedded in highly scattering medium, i.e., brain cortex, we developed and formulated a novel dual-depth sampling and normalization strategy that allowed us to minimize the detrimental effect of ubiquitous tissue scattering. We applied our newly developed approach to monitor the hemodynamic response in mouse cortex after focal photothrombosis. We observed vessel dilatation, which was negatively correlated with the original vessel diameter, in the penumbra region. The sO2 of vessels in the penumbra region also dropped below normal range after focal ischemia. PMID:27699105

  20. Fine particulate matter results in hemodynamic changes in subjects with blunted nocturnal blood pressure dipping.

    PubMed

    Chen, Szu-Ying; Chan, Chang-Chuan; Lin, Yu-Lun; Hwang, Jing-Shiang; Su, Ta-Chen

    2014-05-01

    Particulate matter with aerodynamic diameter of <2.5 μm (PM2.5) is associated with blood pressure and hemodynamic changes. Blunted nocturnal blood pressure dipping is a major risk factor for cardiovascular events; limited information is available on whether PM2.5 exposure-related hemodynamic changes vary with day-night blood pressure circadian rhythms. In this study, we enrolled 161 subjects and monitored the changes in ambulatory blood pressure and hemodynamics for 24h. The day-night blood pressure and cardiovascular metrics were calculated according to the sleep-wake cycles logged in the subject׳s diary. The effects of PM2.5 exposure on blood pressure and hemodynamic changes were analyzed using generalized linear mixed-effect model. After adjusting for potential confounders, a 10-μg/m(3) increase in PM2.5 was associated with 1.0 mmHg [95% confidence interval (CI): 0.2-1.8 mmHg] narrowing in the pulse pressure, 3.1% (95% CI: 1.4-4.8%) decrease in the maximum rate of left ventricular pressure rise, and 3.6% (95% CI: 1.6-5.7%) increase in systemic vascular resistance among 79 subjects with nocturnal blood pressure dip of <10%. In contrast, PM2.5 was not associated with any changes in cardiovascular metrics among 82 subjects with nocturnal blood pressure dip of ≥10%. Our findings demonstrate that short-term exposure to PM2.5 contributes to pulse pressure narrowing along with cardiac and vasomotor dysfunctions in subjects with nocturnal blood pressure dip of <10%.

  1. Atrium of stone: A case of confined left atrial calcification without hemodynamic compromise.

    PubMed

    Jones, Christopher; Lodhi, Aadil Mubeen; Cao, Long Bao; Chagarlamudi, Arjun Kumar; Movahed, Assad

    2014-05-16

    Dystrophic cardiac calcification is often associated with conditions causing systemic inflammation and when present, is usually extensive, often encompassing multiple cardiac chambers and valves. We present an unusual case of dystrophic left atrial calcification in the setting of end stage renal disease on hemodialysis diagnosed by echocardiography and computed tomography. Significant calcium deposition is confined within the walls of the left atrium with no involvement of the mitral valve, and no hemodynamic effects. PMID:24868514

  2. Abnormal hemodynamic response to forepaw stimulation in rat brain after cocaine injection

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Park, Kicheon; Choi, Jeonghun; Pan, Yingtian; Du, Congwu

    2015-03-01

    Simultaneous measurement of hemodynamics is of great importance to evaluate the brain functional changes induced by brain diseases such as drug addiction. Previously, we developed a multimodal-imaging platform (OFI) which combined laser speckle contrast imaging with multi-wavelength imaging to simultaneously characterize the changes in cerebral blood flow (CBF), oxygenated- and deoxygenated- hemoglobin (HbO and HbR) from animal brain. Recently, we upgraded our OFI system that enables detection of hemodynamic changes in response to forepaw electrical stimulation to study potential brain activity changes elicited by cocaine. The improvement includes 1) high sensitivity to detect the cortical response to single forepaw electrical stimulation; 2) high temporal resolution (i.e., 16Hz/channel) to resolve dynamic variations in drug-delivery study; 3) high spatial resolution to separate the stimulation-evoked hemodynamic changes in vascular compartments from those in tissue. The system was validated by imaging the hemodynamic responses to the forepaw-stimulations in the somatosensory cortex of cocaine-treated rats. The stimulations and acquisitions were conducted every 2min over 40min, i.e., from 10min before (baseline) to 30min after cocaine challenge. Our results show that the HbO response decreased first (at ~4min) followed by the decrease of HbR response (at ~6min) after cocaine, and both did not fully recovered for over 30min. Interestingly, while CBF decreased at 4min, it partially recovered at 18min after cocaine administration. The results indicate the heterogeneity of cocaine's effects on vasculature and tissue metabolism, demonstrating the unique capability of optical imaging for brain functional studies.

  3. fNIRS derived hemodynamic signals and electrodermal responses in a sequential risk-taking task.

    PubMed

    Holper, Lisa; ten Brincke, Robert H W; Wolf, Martin; Murphy, Ryan O

    2014-04-01

    The study measured cortical hemodynamic signals and peripheral correlates of decision makers during a dynamic risky task, the Just One More task (JOM), in which the risky decision entails choosing whether to incrementally increase accumulated earnings at the risk of ruin (going bust ending up with nothing). Twenty subjects participated in multiple instantiations of this task in which the probability of ruin and size of the stakes varied. Physiological correlates were simultaneously quantified by functional near-infrared spectroscopy (fNIRS) over dorsolateral prefrontal cortex (DLPFC) and electrodermal activity (EDA). First, in the task decision phase (i.e., when subjects are contemplating options before making a choice) probability of ruin had a dissociating effect on fNIRS and EDA. fNIRS derived DLPFC hemodynamic signals reflected a subjective value signal, correlating positively with individual risk attitude. Contrary, EDA reflected the probability of ruin in terms of a common affective measure, irrespective of individuals׳ risk attitude. Second, during the task outcome phase (i.e., the time after subjects have made a choice and observed the outcomes) fNIRS and EDA revealed opposite patterns. While fNIRS derived DLPFC hemodynamic signals were larger in response to gains, EDA signals were larger in response to losses; both patterns were statistically independent of individual risk attitude. Lastly, fNIRS derived DLPFC hemodynamic signals in the decision phase correlated positively with the mean round earnings, providing a measure of the quality of the individual decision-making performance. Together with the positive correlation with individual risk attitude, our findings indicate that fNIRS signals, but not EDA, could be taken as a useful method for studying individual risk attitude and task performance in dynamic risky decision-making. PMID:24530267

  4. A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase.

    PubMed

    Jahandardoost, Mehdi; Fradet, Guy; Mohammadi, Hadi

    2015-03-01

    A powerful alternative means to study the hemodynamics of bileaflet mechanical heart valves is the computational fluid dynamics method. It is well recognized that computational fluid dynamics allows reliable physiological blood flow simulation and measurements of flow parameters. To date, in almost all of the modeling studies on the hemodynamics of bileaflet mechanical heart valves, a velocity (mass flow)-based boundary condition and an axisymmetric geometry for the aortic root have been assigned, which, to some extent, are erroneous. Also, there have been contradictory reports of the profile of velocity in downstream of leaflets, that is, in some studies, it is suggested that the maximum blood velocity occurs in the lateral orifice, and in some other studies, it is postulated that the maximum velocities in the main and lateral orifices are identical. The reported values for the peak velocities range from 1 to 3 m/s, which highly depend on the model assumptions. The objective of this study is to demonstrate the importance of the exact anatomical model of the aortic root and the realistic boundary conditions in the hemodynamics of the bileaflet mechanical heart valves. The model considered in this study is based on the St Jude Medical valve in a novel modeling platform. Through a more realistic geometrical model for the aortic root and the St Jude Medical valve, we have developed a new set of boundary conditions in order to be used for the assessment of the hemodynamics of aortic bileaflet mechanical heart valves. The results of this study are significant for the design improvement of conventional bileaflet mechanical heart valves and for the design of the next generation of prosthetic valves.

  5. Multi-Segment Hemodynamic and Volume Assessment With Impedance Plethysmography: Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Ku, Yu-Tsuan E.; Montgomery, Leslie D.; Webbon, Bruce W. (Technical Monitor)

    1995-01-01

    Definition of multi-segmental circulatory and volume changes in the human body provides an understanding of the physiologic responses to various aerospace conditions. We have developed instrumentation and testing procedures at NASA Ames Research Center that may be useful in biomedical research and clinical diagnosis. Specialized two, four, and six channel impedance systems will be described that have been used to measure calf, thigh, thoracic, arm, and cerebral hemodynamic and volume changes during various experimental investigations.

  6. Manipulation of magnetic nanoparticle retention and hemodynamic consequences in microcirculation: assessment by laser speckle imaging

    PubMed Central

    Ma, Yunn-Hwa; Chen, Si-Yi; Tu, Shu-Ju; Yang, Hung-Wei; Liu, Hao-Li

    2012-01-01

    Magnetic nanoparticles (MNPs) have been proposed for targeted or embolization therapeutics. How MNP retention occurs in circulation may critically determine local hemodynamics, tissue distribution of MNPs, and the therapeutic effects. We attempted to establish a microcirculation model to study the magnetic capture of MNPs in small vessels and to determine the factors affecting MNP retention. Two-dimensional hemodynamic changes in response to magnet-induced MNP retention in the microvessels of the cremaster muscle in vivo were observed in a real-time manner using a laser speckle imaging technique. Changes in tissue perfusion of the cremaster muscle appeared to be closely correlated with the location of the magnet placement underneath the muscle in response to intra-arterial administration of dextran-coated MNPs. Magnet-related retention was observed along the edge of the magnet, as corroborated by the results of histology analysis and microcomputed tomography. In these preparations, tissue iron content almost doubled, as revealed by inductively coupled plasma optical emission spectroscopy. In addition, MNP retention was associated with reduced downstream flow in a dose-dependent manner. Dissipation of MNPs (5 mg/kg) occurred shortly after removal of the magnet, which was associated with significant recovery of tissue flow. However, MNP dissipation did not easily occur after administration of a higher MNP dose (10 mg/kg) or prolonged exposure to the magnetic field. An ultrasound after removal of the magnet may induce the partial dispersion of MNPs and thus partially improve hemodynamics. In conclusion, our results revealed the important correlation of local MNP retention and hemodynamic changes in microcirculation, which can be crucial in the application of MNPs for effective targeted therapeutics. PMID:22745544

  7. Association Between Hemodynamic Profile, Physical Capacity and Quality of Life in Pulmonary Hypertension

    PubMed Central

    Torres, Diego de Faria Magalhães; Zin, Walter Araujo; Lopes, Agnaldo José; Vigário, Patrícia dos Santos; Garcia, Marcelo Iorio; Waetge, Daniel; Bandeira, Marcelo Luiz da Silva; Bessa, Luiz Gustavo Pignataro; Guimarães, Fernando Silva

    2015-01-01

    Background No studies have described and evaluated the association between hemodynamics, physical limitations and quality of life in patients with pulmonary hypertension (PH) without concomitant cardiovascular or respiratory disease. Objective To describe the hemodynamic profile, quality of life and physical capacity of patients with PH from groups I and IV and to study the association between these outcomes. Methods Cross-sectional study of patients with PH from clinical groups I and IV and functional classes II and III undergoing the following assessments: hemodynamics, exercise tolerance and quality of life. Results This study assessed 20 patients with a mean age of 46.8 ± 14.3 years. They had pulmonary capillary wedge pressure of 10.5 ± 3.7 mm Hg, 6-minute walk distance test (6MWDT) of 463 ± 78 m, oxygen consumption at peak exercise of 12.9 ± 4.3 mLO2.kg-1.min-1 and scores of quality of life domains < 60%. There were associations between cardiac index (CI) and ventilatory equivalent for CO2 (r=-0.59, p <0.01), IC and ventilatory equivalent for oxygen (r=-0.49, p<0.05), right atrial pressure (RAP) and 'general health perception' domain (r=-0.61, p<0.01), RAP and 6MWTD (r=-0.49, p<0.05), pulmonary vascular resistance (PVR) and 'physical functioning' domain (r=-0.56, p<0.01), PVR and 6MWTD (r=-0.49, p<0.05) and PVR index and physical capacity (r=-0.51, p<0.01). Conclusion Patients with PH from groups I and IV and functional classes II and III exhibit a reduction in physical capacity and in the physical and mental components of quality of life. The hemodynamic variables CI, diastolic pulmonary arterial pressure, RAP, PVR and PVR index are associated with exercise tolerance and quality of life domains. PMID:25742419

  8. A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase.

    PubMed

    Jahandardoost, Mehdi; Fradet, Guy; Mohammadi, Hadi

    2015-03-01

    A powerful alternative means to study the hemodynamics of bileaflet mechanical heart valves is the computational fluid dynamics method. It is well recognized that computational fluid dynamics allows reliable physiological blood flow simulation and measurements of flow parameters. To date, in almost all of the modeling studies on the hemodynamics of bileaflet mechanical heart valves, a velocity (mass flow)-based boundary condition and an axisymmetric geometry for the aortic root have been assigned, which, to some extent, are erroneous. Also, there have been contradictory reports of the profile of velocity in downstream of leaflets, that is, in some studies, it is suggested that the maximum blood velocity occurs in the lateral orifice, and in some other studies, it is postulated that the maximum velocities in the main and lateral orifices are identical. The reported values for the peak velocities range from 1 to 3 m/s, which highly depend on the model assumptions. The objective of this study is to demonstrate the importance of the exact anatomical model of the aortic root and the realistic boundary conditions in the hemodynamics of the bileaflet mechanical heart valves. The model considered in this study is based on the St Jude Medical valve in a novel modeling platform. Through a more realistic geometrical model for the aortic root and the St Jude Medical valve, we have developed a new set of boundary conditions in order to be used for the assessment of the hemodynamics of aortic bileaflet mechanical heart valves. The results of this study are significant for the design improvement of conventional bileaflet mechanical heart valves and for the design of the next generation of prosthetic valves. PMID:25833999

  9. Effect of Flow Pulsatility on Modeling the Hemodynamics in the Total Cavopulmonary Connection

    PubMed Central

    khiabani, Reza H.; Restrepo, Maria; Tang, Elaine; De Zélicourt, Diane; Sotiropoulos, Fotis; Fogel, Mark; Yoganathan, Ajit P.

    2012-01-01

    Total Cavopulmonary Connection is the result of a series of palliative surgical repairs performed on patients with single ventricle heart defects. The resulting anatomy has complex and unsteady hemodynamics characterized by flow mixing and flow separation. Although varying degrees of flow pulsatility have been observed in vivo, non-pulsatile (time-averaged) boundary conditions have traditionally been assumed in hemodynamic modeling, and only recently have pulsatile conditions been incorporated without completely characterizing their effect or importance. In this study, 3D numerical simulations with both pulsatile and non-pulsatile boundary conditions were performed for 24 patients with different anatomies and flow boundary conditions from Georgia Tech database. Flow structures, energy dissipation rates and pressure drops were compared under rest and simulated exercise conditions. It was found that flow pulsatility is the primary factor in determining the appropriate choice of boundary conditions, whereas the anatomic configuration and cardiac output had secondary effects. Results show that the hemodynamics can be strongly influenced by the presence of pulsatile flow. However, there was a minimum pulsatility threshold, identified by defining a weighted pulsatility index (wPI), above which the influence was significant. It was shown that when wPI < 30%, the relative error in hemodynamic predictions using time-averaged boundary conditions was less than 10% compared to pulsatile simulations. In addition, when wPI <50, the relative error was less than 20%. A correlation was introduced to relate wPI to the relative error in predicting the flow metrics with non-pulsatile flow conditions. PMID:22841650

  10. A Critical Role for Proinflammatory Behavior of Smooth Muscle Cells in Hemodynamic Initiation of Intracranial Aneurysm

    PubMed Central

    Mandelbaum, Max; Kolega, John; Dolan, Jennifer M.; Siddiqui, Adnan H.; Meng, Hui

    2013-01-01

    Background Intracranial aneurysm initiation is poorly understood, although hemodynamic insult is believed to play an important role in triggering the pathology. It has recently been found in a rabbit model that while macrophages are absent during hemodynamic aneurysm initiation, matrix metalloproteinases (MMPs) are elevated and co-localize with smooth muscle cells (SMCs). This study investigates whether SMCs play a mechanistic role in aneurysm initiation triggered by hemodynamics. Methods Aneurysmal damage was induced at the basilar terminus via bilateral common carotid artery ligation in rabbits (n = 45, plus 7 sham controls). 16 ligated rabbits were treated with doxycycline to inhibit MMPs, 7 received clodronate liposomes to deplete circulating monocytes, and the rest received no drug. Effects of the treatments on aneurysm development were assessed histologically 5 days and 6 months after ligation. MMP production and expression of inflammatory markers by SMCs was monitored by immunohistochemistry and in situ hybridization. Results Treatment with doxycycline attenuated aneurysmal development examined at 5 days and 6 months, suggesting that MMPs contribute to aneurysm initiation. However, systemic depletion of macrophages did not decrease MMPs or suppress aneurysmal development. Immunofluorescence showed that during aneurysm initiation MMP-2 and MMP-9 were distributed in SMCs, and in situ hybridization indicated that they were transcribed by SMCs. In regions of early aneurysmal lesion, SMCs exhibited decreased expression of smooth muscle actin and increased NF-κB and MCP-1 expressions. Conclusions During aneurysm initiation triggered by hemodynamics, SMCs rather than macrophages are responsible for MMP production that is critical for aneurysmal lesion development. These SMCs exhibit proinflammatory behavior. PMID:24023941

  11. Hemodynamic challenge to early mobilization after cardiac surgery: A pilot study

    PubMed Central

    Cassina, Tiziano; Putzu, Alessandro; Santambrogio, Luisa; Villa, Michele; Licker, Marc Joseph

    2016-01-01

    Background: Active mobilization is a key component in fast-track surgical strategies. Following major surgery, clinicians are often reluctant to mobilize patients arguing that circulatory homeostasis would be impaired as a result of myocardial stunning, fluid shift, and autonomic dysfunction. Aims: We examined the feasibility and safety of a mobilization protocol 12–24 h after elective cardiac surgery. Setting and Design: This observational study was performed in a tertiary nonacademic cardiovascular Intensive Care Unit. Materials and Methods: Over a 6-month period, we prospectively evaluated the hemodynamic response to a two-staged mobilization procedure in 53 consecutive patients. Before, during, and after the mobilization, hemodynamics parameters were recorded, including the central venous oxygen saturation (ScvO2), lactate concentrations, mean arterial pressure (MAP), heart rate (HR), right atrial pressure (RAP), and arterial oxygen saturation (SpO2). Any adverse events were documented. Results: All patients successfully completed the mobilization procedure. Compared with the supine position, mobilization induced significant increases in arterial lactate (34.6% [31.6%, 47.6%], P = 0.0022) along with reduction in RAP (−33% [−21%, −45%], P < 0.0001) and ScvO2 (−7.4% [−5.9%, −9.9%], P = 0.0002), whereas HR and SpO2 were unchanged. Eighteen patients (34%) presented a decrease in MAP > 10% and nine of them (17%) required treatment. Hypotensive patients experienced a greater decrease in ScvO2 (−18 ± 5% vs. −9 ± 4%, P = 0.004) with similar changes in RAP and HR. All hemodynamic parameters, but arterial lactate, recovered baseline values after resuming the horizontal position. Conclusions: Early mobilization after cardiac surgery appears to be a safe procedure as far as it is performed under close hemodynamic and clinical monitoring in an intensive care setting. PMID:27397446

  12. Intracranial microprobe for evaluating neuro-hemodynamic coupling in unanesthetized human neocortex

    PubMed Central

    Keller, Corey J.; Cash, Sydney S.; Narayanan, Suresh; Wang, Chunmao; Kuzniecky, Ruben; Carlson, Chad; Devinsky, Orrin; Thesen, Thomas; Doyle, Werner; Sassaroli, Angelo; Boas, David A.; Ulbert, Istvan; Halgren, Eric

    2009-01-01

    Measurement of the blood-oxygen-level dependent (BOLD) response with fMRI has revolutionized cognitive neuroscience and is increasingly important in clinical care. The BOLD response reflects changes in deoxy-hemoglobin concentration, blood volume, and blood flow. These hemodynamic changes ultimately result from neuronal firing and synaptic activity, but the linkage between these domains is complex, poorly understood, and may differ across species, cortical areas, diseases, and cognitive states. We describe here a technique that can measure neural and hemodynamic changes simultaneously from cortical microdomains in waking humans. We utilize a “laminar optode,” a linear array of microelectrodes for electrophysiological measures paired with a micro-optical device for hemodynamic measurements. Optical measurements include laser Doppler to estimate cerebral blood flow as well as point spectroscopy to estimate oxy- and deoxy-hemoglobin concentrations. The microelectrode array records local field potential gradients (PG) and multi-unit activity (MUA) at 24 locations spanning the cortical depth, permitting estimation of population trans-membrane current flows (Current Source Density, CSD) and population cell firing in each cortical lamina. Comparison of the laminar CSD/MUA profile with the origins and terminations of cortical circuits allows activity in specific neuronal circuits to be inferred and then directly compared to hemodynamics. Access is obtained in epileptic patients during diagnostic evaluation for surgical therapy. Validation tests with relatively well-understood manipulations (EKG, breath-holding, cortical electrical stimulation) demonstrate the expected responses. This device can provide a new and robust means for obtaining detailed, quantitative data for defining neurovascular coupling in awake humans. PMID:19428529

  13. Hemodynamic Flow-Induced Mechanotransduction Signaling Influences the Radiation Response of the Vascular Endothelium.

    PubMed

    Natarajan, Mohan; Aravindan, Natarajan; Sprague, Eugene A; Mohan, Sumathy

    2016-08-01

    Hemodynamic shear stress is defined as the physical force exerted by the continuous flow of blood in the vascular system. Endothelial cells, which line the inner layer of blood vessels, sense this physiological force through mechanotransduction signaling and adapt to maintain structural and functional homeostasis. Hemodynamic flow, shear stress and mechanotransduction signaling are, therefore, an integral part of endothelial pathophysiology. Although this is a well-established concept in the cardiovascular field, it is largely dismissed in studies aimed at understanding radiation injury to the endothelium and subsequent cardiovascular complications. We and others have reported on the differential response of the endothelium when the cells are under hemodynamic flow shear compared with static culture. Further, we have demonstrated significant differences in the gene expression of static versus shear-stressed irradiated cells in four key pathways, reinforcing the importance of shear stress in understanding radiation injury of the endothelium. This article further emphasizes the influence of hemodynamic shear stress and the associated mechanotransduction signaling on physiological functioning of the vascular endothelium and underscores its significance in understanding radiation injury to the vasculature and associated cardiac complications. Studies of radiation effect on endothelial biology and its implication on cardiotoxicity and vascular complications thus far have failed to highlight the significance of these factors. Factoring in these integral parts of the endothelium will enhance our understanding of the contribution of the endothelium to radiation biology. Without such information, the current approaches to studying radiation-induced injury to the endothelium and its consequences in health and disease are limited. PMID:27387860

  14. Hemodynamic low-frequency oscillation reflects resting-state neuronal activity in rodent brain

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Liu, Peng; Li, James; Pan, Yingtian; Du, Congwu

    2015-03-01

    Brain functional connectivity is mapped using spontaneous low-frequency oscillations (LFOs) in blood-oxygen-leveldependent (BOLD) signals using fMRI. However, the origin of spontaneous BOLD oscillations remains elusive. Specifically, the coupling of regional hemodynamic LFOs to neuronal activity in a resting brain is rarely examined directly. Here we present a method based on instantaneous-frequency (IF) analysis to detect regional LFOs of cerebral blood flow (CBF) along with local-field potential (LFP) changes of neurons in resting state to study neurovascular coupling. CBF and LFP were simultaneously acquired using laser Doppler flowmetry (LDF) and electroencephalography in the rat's somatosensory cortex with high temporal resolution (i.e., 20Hz for CBF and 2kHz for LDF, respectively). Instead of fast Fourier transform analysis, a peak-detection algorithm was used to define the LFP activities and CBF spontaneous oscillations in the time domain and the time lapses were used to calculate the IFs of hemodynamic (i.e., CBF) oscillations and neuronal (i.e., LFP) activities. Our results showed that the CBF mostly oscillated at ~0.1Hz with a full-half-bandwidth of [0.08Hz, 0.15Hz]. In addition, the maximal frequency of LFP firings was also approximately at 0.1Hz, which collaborated with to the frequency of CBF oscillations. Interestingly, CBF increased linearly with the LFP activity up to 0.15Hz (r=0.93), and both signals then decreased rapidly as a function of activity frequency. This indicates the spontaneous hemodynamic LFOs were associated with neuronal activities, thus confirming the neuronal origin of the hemodynamic oscillations.

  15. Time-Series Interactions of Gene Expression, Vascular Growth and Hemodynamics during Early Embryonic Arterial Development

    PubMed Central

    Goktas, Selda; Uslu, Fazil E.; Kowalski, William J.; Ermek, Erhan; Keller, Bradley B.

    2016-01-01

    The role of hemodynamic forces within the embryo as biomechanical regulators for cardiovascular morphogenesis, growth, and remodeling is well supported through the experimental studies. Furthermore, clinical experience suggests that perturbed flow disrupts the normal vascular growth process as one etiology for congenital heart diseases (CHD) and for fetal adaptation to CHD. However, the relationships between hemodynamics, gene expression and embryonic vascular growth are poorly defined due to the lack of concurrent, sequential in vivo data. In this study, a long-term, time-lapse optical coherence tomography (OCT) imaging campaign was conducted to acquire simultaneous blood velocity, pulsatile micro-pressure and morphometric data for 3 consecutive early embryonic stages in the chick embryo. In conjunction with the in vivo growth and hemodynamics data, in vitro reverse transcription polymerase chain reaction (RT-PCR) analysis was performed to track changes in transcript expression relevant to histogenesis and remodeling of the embryonic arterial wall. Our non-invasive extended OCT imaging technique for the microstructural data showed continuous vessel growth. OCT data coupled with the PIV technique revealed significant but intermitted increases in wall shear stress (WSS) between first and second assigned stages and a noticeable decrease afterwards. Growth rate, however, did not vary significantly throughout the embryonic period. Among all the genes studied, only the MMP-2 and CASP-3 expression levels remained unchanged during the time course. Concurrent relationships were obtained among the transcriptional modulation of the genes, vascular growth and hemodynamics-related changes. Further studies are indicated to determine cause and effect relationships and reversibility between mechanical and molecular regulation of vasculogenesis. PMID:27552150

  16. Main pulmonary arterial wall shear stress correlates with invasive hemodynamics and stiffness in pulmonary hypertension

    PubMed Central

    Kheyfets, Vitaly O.; Schroeder, Joyce D.; Dunning, Jamie; Shandas, Robin; Buckner, J. Kern; Browning, James; Hertzberg, Jean; Hunter, Kendall S.; Fenster, Brett E.

    2016-01-01

    Abstract Pulmonary hypertension (PH) is associated with proximal pulmonary arterial remodeling characterized by increased vessel diameter, wall thickening, and stiffness. In vivo assessment of wall shear stress (WSS) may provide insights into the relationships between pulmonary hemodynamics and vascular remodeling. We investigated the relationship between main pulmonary artery (MPA) WSS and pulmonary hemodynamics as well as markers of stiffness. As part of a prospective study, 17 PH patients and 5 controls underwent same-day four-dimensional flow cardiac magnetic resonance imaging (4-D CMR) and right heart catheterization. Streamwise velocity profiles were generated in the cross-sectional MPA in 45° increments from velocity vector fields determined by 4-D CMR. WSS was calculated as the product of hematocrit-dependent viscosity and shear rate generated from the spatial gradient of the velocity profiles. In-plane average MPA WSS was significantly decreased in the PH cohort compared with that in controls (0.18 ± 0.07 vs. 0.32 ± 0.08 N/m2; P = 0.01). In-plane MPA WSS showed strong inverse correlations with multiple hemodynamic indices, including pulmonary resistance (ρ = −0.74, P < 0.001), mean pulmonary pressure (ρ = −0.64, P = 0.006), and elastance (ρ = −0.70, P < 0.001). In addition, MPA WSS had significant associations with markers of stiffness, including capacitance (ρ = 0.67, P < 0.001), distensibility (ρ = 0.52, P = 0.013), and elastic modulus (ρ = −0.54, P = 0.01). In conclusion, MPA WSS is decreased in PH and is significantly associated with invasive hemodynamic indices and markers of stiffness. 4-D CMR–based assessment of WSS may represent a novel methodology to study blood-vessel wall interactions in PH. PMID:27076906

  17. Scimitar syndrome: morphological diagnosis and assessment of hemodynamic significance by magnetic resonance imaging.

    PubMed

    Kramer, Ulrich; Dörnberger, Volker; Fenchel, Michael; Stauder, Norbert; Claussen, Claus D; Miller, Stephan

    2003-12-01

    Scimitar syndrome has a variable presentation depending on the age at which the diagnosis is made. We report a case of a young woman (age 18 years) with suspected right pulmonary hypoplasia in whom a scimitar syndrome was diagnosed. Using MRI morphological findings and hemodynamic significance of the syndrome were assessed. Left-to-right shunt was calculated from blood flow measurements performed in the ascending aorta, the main pulmonary artery, and the aberrant scimitar vein.

  18. ED 02-3 CLINICAL IMPLICATIONS OF CENTRAL HEMODYNAMICS ON AORTIC AND END-ORGAN DISEASES.

    PubMed

    Hashimoto, Junichiro

    2016-09-01

    The central aorta constitutes the main trunk of the systemic arterial tree. It dilates passively with cardiac ejection during systole and then constricts with its recoil function during diastole, thereby regulating blood pressure and blood flow. The central pulsatile hemodynamics affects local hemodynamics within as well as downstream of the aorta (e.g., end organs).The aorta progressively stiffens and dilates with advancing age, and such age-dependent change is accelerated by hypertension. According to the law of Laplace, wall stress depends on the diameter and pressure of the blood vessel. This has been confirmed by substantial studies which have associated baseline aortic diameter with subsequent development of aortic dissection and progressive dilatation of aortic lumen. This law can also imply potential importance of local pressure within the aorta (i.e., the central pressure) in predicting the development and progression of aortic aneurysms.Several previous studies have shown that hypertension (together with age and obesity) is related to dilatation of the proximal ascending aorta (rather than of the aortic root). In addition, aortic blood flow abnormality may also be importantly related to aortic dilatation because of strong positive association between the diastole flow reversal and lumen diameter in the proximal thoracic aorta. As for the abdominal (infrarenal) aorta, aneurysmal development and progression have been attributed to aortic segmental stiffening (of the bifurcational versus infrarenal segment) and aortic pressure elevation, respectively.Central pulsatile pressure not only represents aortic wall stress but also determines cardiac afterload and microvascular wall stress in the brain and kidney. Central pulsatile flow (in both directions) could also affect the flow distribution into the upper and lower parts of the body and control end-organ function. Aortic structural change (including segmental stiffening and aneurysmal formation) causes central

  19. Two-dimensional optical tomography of hemodynamic changes in a preterm infant brain

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Xue, Yuan; Zhao, Huijuan; Kusaka, Takashi; Ueno, Masanori; Yamada, Yukio

    2007-08-01

    Our preliminary results on two-dimensional (2D) optical tomographic imaging of hemodynamic changes in a preterm infant brain are reported. We use the established 16-channel time-correlated single photon counting system for the detection and generalized pulse spectrum technique based algorithm for the image reconstruction. The experiments demonstrate that diffuse optical tomography may be a potent means for investigating brain functions and neural development of infant brains in the perinatal period.

  20. Correlation Between Aneurysm Size and Hemodynamics in One Individual with Multiple Small Intracranial Aneurysms.

    PubMed

    Jou, Liangder; Britz, Gavin

    2016-01-01

    Objective A large number of cases are needed in the patient-specific modeling of intracranial aneurysms to establish the statistical significance due to individual variation of risk factors that are difficult to account for. However, these risk factors are critical in hemorrhage risk as demonstrated in large clinical studies. Rupture risks for aneurysms in an individual are easier to compare because these aneurysms are under the same physiological environment, and their only differences are the local hemodynamic factors associated with their anatomic locations. Methods Eight small aneurysms (< 7 mm) from one individual were analyzed using patient-specific hemodynamic modeling. Four scenarios with different perfusion assumptions were performed to account for the flow rate at two smaller communicating arteries. Wall shear stresses (WSS) at these aneurysms were compared to determine their relationship with the aneurysm size. Results Each of the three largest aneurysms is either the most proximal or distal aneurysm in a given artery so that blood pressure does not have a direct influence on aneurysm size. No wall shear stress-derived hemodynamic variables are found to be related to aneurysm size. Discussion A study of multiple aneurysms from one individual offers a unique opportunity to examine various hemodynamic factors without selection biases. Aneurysms greater than 4 mm (Group 1) have a higher product of maximum WSS and area of low WSS; aneurysms smaller than 4 mm (Group 2) have a lower product of maximum WSS and area of low WSS. In addition, aneurysm size is linearly correlated with the flow rate at the parent artery in each group. PMID:27555981

  1. Correlation Between Aneurysm Size and Hemodynamics in One Individual with Multiple Small Intracranial Aneurysms

    PubMed Central

    Britz, Gavin

    2016-01-01

    Objective A large number of cases are needed in the patient-specific modeling of intracranial aneurysms to establish the statistical significance due to individual variation of risk factors that are difficult to account for. However, these risk factors are critical in hemorrhage risk as demonstrated in large clinical studies. Rupture risks for aneurysms in an individual are easier to compare because these aneurysms are under the same physiological environment, and their only differences are the local hemodynamic factors associated with their anatomic locations. Methods Eight small aneurysms (< 7 mm) from one individual were analyzed using patient-specific hemodynamic modeling. Four scenarios with different perfusion assumptions were performed to account for the flow rate at two smaller communicating arteries. Wall shear stresses (WSS) at these aneurysms were compared to determine their relationship with the aneurysm size. Results Each of the three largest aneurysms is either the most proximal or distal aneurysm in a given artery so that blood pressure does not have a direct influence on aneurysm size. No wall shear stress-derived hemodynamic variables are found to be related to aneurysm size. Discussion A study of multiple aneurysms from one individual offers a unique opportunity to examine various hemodynamic factors without selection biases. Aneurysms greater than 4 mm (Group 1) have a higher product of maximum WSS and area of low WSS; aneurysms smaller than 4 mm (Group 2) have a lower product of maximum WSS and area of low WSS. In addition, aneurysm size is linearly correlated with the flow rate at the parent artery in each group. PMID:27555981

  2. Time-Series Interactions of Gene Expression, Vascular Growth and Hemodynamics during Early Embryonic Arterial Development.

    PubMed

    Goktas, Selda; Uslu, Fazil E; Kowalski, William J; Ermek, Erhan; Keller, Bradley B; Pekkan, Kerem

    2016-01-01

    The role of hemodynamic forces within the embryo as biomechanical regulators for cardiovascular morphogenesis, growth, and remodeling is well supported through the experimental studies. Furthermore, clinical experience suggests that perturbed flow disrupts the normal vascular growth process as one etiology for congenital heart diseases (CHD) and for fetal adaptation to CHD. However, the relationships between hemodynamics, gene expression and embryonic vascular growth are poorly defined due to the lack of concurrent, sequential in vivo data. In this study, a long-term, time-lapse optical coherence tomography (OCT) imaging campaign was conducted to acquire simultaneous blood velocity, pulsatile micro-pressure and morphometric data for 3 consecutive early embryonic stages in the chick embryo. In conjunction with the in vivo growth and hemodynamics data, in vitro reverse transcription polymerase chain reaction (RT-PCR) analysis was performed to track changes in transcript expression relevant to histogenesis and remodeling of the embryonic arterial wall. Our non-invasive extended OCT imaging technique for the microstructural data showed continuous vessel growth. OCT data coupled with the PIV technique revealed significant but intermitted increases in wall shear stress (WSS) between first and second assigned stages and a noticeable decrease afterwards. Growth rate, however, did not vary significantly throughout the embryonic period. Among all the genes studied, only the MMP-2 and CASP-3 expression levels remained unchanged during the time course. Concurrent relationships were obtained among the transcriptional modulation of the genes, vascular growth and hemodynamics-related changes. Further studies are indicated to determine cause and effect relationships and reversibility between mechanical and molecular regulation of vasculogenesis. PMID:27552150

  3. ED 02-3 CLINICAL IMPLICATIONS OF CENTRAL HEMODYNAMICS ON AORTIC AND END-ORGAN DISEASES.

    PubMed

    Hashimoto, Junichiro

    2016-09-01

    The central aorta constitutes the main trunk of the systemic arterial tree. It dilates passively with cardiac ejection during systole and then constricts with its recoil function during diastole, thereby regulating blood pressure and blood flow. The central pulsatile hemodynamics affects local hemodynamics within as well as downstream of the aorta (e.g., end organs).The aorta progressively stiffens and dilates with advancing age, and such age-dependent change is accelerated by hypertension. According to the law of Laplace, wall stress depends on the diameter and pressure of the blood vessel. This has been confirmed by substantial studies which have associated baseline aortic diameter with subsequent development of aortic dissection and progressive dilatation of aortic lumen. This law can also imply potential importance of local pressure within the aorta (i.e., the central pressure) in predicting the development and progression of aortic aneurysms.Several previous studies have shown that hypertension (together with age and obesity) is related to dilatation of the proximal ascending aorta (rather than of the aortic root). In addition, aortic blood flow abnormality may also be importantly related to aortic dilatation because of strong positive association between the diastole flow reversal and lumen diameter in the proximal thoracic aorta. As for the abdominal (infrarenal) aorta, aneurysmal development and progression have been attributed to aortic segmental stiffening (of the bifurcational versus infrarenal segment) and aortic pressure elevation, respectively.Central pulsatile pressure not only represents aortic wall stress but also determines cardiac afterload and microvascular wall stress in the brain and kidney. Central pulsatile flow (in both directions) could also affect the flow distribution into the upper and lower parts of the body and control end-organ function. Aortic structural change (including segmental stiffening and aneurysmal formation) causes central

  4. Acute effect of cycling intervention on carotid arterial hemodynamics: basketball athletes versus sedentary controls

    PubMed Central

    2015-01-01

    Objective To compare the acute effects of a cycling intervention on carotid arterial hemodynamics between basketball athletes and sedentary controls. Methods Ten young long-term trained male basketball athletes (BA) and nine age-matched male sedentary controls (SC) successively underwent four bouts of exercise on a bicycle ergometer at the same workload. Hemodynamic variables at right common carotid artery were determined at rest and immediately following each bout of exercise. An ANCOVA was used to compare differences between the BA and SC groups at rest and immediately following the cycling intervention. The repeated ANOVA was used to assess differences between baseline and each bout of exercise within the BA or SC group. Results In both groups, carotid hemodynamic variables showed significant differences at rest and immediately after the cycling intervention. At rest, carotid arterial stiffness was significantly decreased and carotid arterial diameter was significantly increased in the BA group as compared to the SC group. Immediately following the cycling intervention, carotid arterial stiffness showed no obvious changes in the BA group but significantly increased in the SC group. It is worth noting that while arterial stiffness was lower in the BA group than in the SC group, the oscillatory shear index (OSI) was significantly higher in the BA group than in the SC group both at rest and immediately following the cycling intervention. Conclusion Long-term basketball exercise had a significant impact on common carotid arterial hemodynamic variables not only at rest but also after a cycling intervention. The role of OSI in the remodeling of arterial structure and function in the BA group at rest and after cycling requires clarification. PMID:25602805

  5. Supporting hemodynamics: what should we target? What treatments should we use?

    PubMed Central

    2013-01-01

    Assessment and monitoring of hemodynamics is a cornerstone in critically ill patients as hemodynamic alteration may become life-threatening in a few minutes. Defining normal values in critically ill patients is not easy, because 'normality' is usually referred to healthy subjects at rest. Defining 'adequate' hemodynamics is easier, which embeds whatever pressure and flow set is sufficient to maintain the aerobic metabolism. We will refer to the unifying hypothesis proposed by Schrier several years ago. Accordingly, the alteration of three independent variables - heart (contractility and rate), vascular tone and intravascular volume - may lead to underfilling of the arterial tree, associated with reduced (as during myocardial infarction or hemorrhage) or expanded (sepsis or cirrhosis) plasma volume. The underfilling is sensed by the arterial baroreceptors, which activate primarily the sympathetic nervous system and renin-angiotensin-aldosterone system, as well as vasopressin, to restore the arterial filling by increasing the vascular tone and retaining sodium and water. Under 'normal' conditions, therefore, the homeostatic system is not activated and water/sodium excretion, heart rate and oxygen extraction are in the range found in normal subjects. When arterial underfilling occurs, the mechanisms are activated (sodium and water retention) - associated with low central venous oxygen saturation (ScvO2) if underfilling is caused by low flow/hypovolemia, or with normal/high ScvO2 if associated with high flow/hypervolemia. Although the correction of hemodynamics should be towards the correction of the independent determinants, the usual therapy performed is volume infusion. An accepted target is ScvO2 >70%, although this ignores the arterial underfilling associated with volume expansion/high flow. For large-volume resuscitation the worst solution is normal saline solution (chloride load, strong ion difference = 0, acidosis). To avoid changes in acid-base equilibrium the

  6. Constraining OCT with Knowledge of Device Design Enables High Accuracy Hemodynamic Assessment of Endovascular Implants

    PubMed Central

    Brown, Jonathan; Lopes, Augusto C.; Kunio, Mie; Kolachalama, Vijaya B.; Edelman, Elazer R.

    2016-01-01

    Background Stacking cross-sectional intravascular images permits three-dimensional rendering of endovascular implants, yet introduces between-frame uncertainties that limit characterization of device placement and the hemodynamic microenvironment. In a porcine coronary stent model, we demonstrate enhanced OCT reconstruction with preservation of between-frame features through fusion with angiography and a priori knowledge of stent design. Methods and Results Strut positions were extracted from sequential OCT frames. Reconstruction with standard interpolation generated discontinuous stent structures. By computationally constraining interpolation to known stent skeletons fitted to 3D ‘clouds’ of OCT-Angio-derived struts, implant anatomy was resolved, accurately rendering features from implant diameter and curvature (n = 1 vessels, r2 = 0.91, 0.90, respectively) to individual strut-wall configurations (average displacement error ~15 μm). This framework facilitated hemodynamic simulation (n = 1 vessel), showing the critical importance of accurate anatomic rendering in characterizing both quantitative and basic qualitative flow patterns. Discontinuities with standard approaches systematically introduced noise and bias, poorly capturing regional flow effects. In contrast, the enhanced method preserved multi-scale (local strut to regional stent) flow interactions, demonstrating the impact of regional contexts in defining the hemodynamic consequence of local deployment errors. Conclusion Fusion of planar angiography and knowledge of device design permits enhanced OCT image analysis of in situ tissue-device interactions. Given emerging interests in simulation-derived hemodynamic assessment as surrogate measures of biological risk, such fused modalities offer a new window into patient-specific implant environments. PMID:26906566

  7. Where is the common sense in aortic valve replacement? A review of hemodynamics and sizing of stented tissue valves.

    PubMed

    Doenst, Torsten; Amorim, Paulo A; Al-Alam, Nidal; Lehmann, Sven; Mukherjee, Chirojit; Faerber, Gloria

    2011-11-01

    Heated debates revolve around the hemodynamic performance of stented aortic tissue valves. Because the opening area strongly influences the generation of a pressure gradient over the prosthesis, and the outer diameter determines which valve actually fits into the aortic root, it would seem logical that the valve with the greatest opening area in relation to its outer diameter should allow the best hemodynamic performance. Interestingly, neither of these 2 parameters is reflected by the manufacturing companies' size labels or suggested sizing strategies. In addition, it is known that valves with the same size label from different companies may differ significantly in their actual dimension (outer diameter). Finally, the manufacturer-suggested sizing strategies differ so much that expected differences from valve design may get lost because of differences in sizing. These size and sizing differences and the lack of information on the geometric opening area complicate true hemodynamic comparisons significantly. Furthermore, some fluid dynamic considerations regarding the determination of opening area by echocardiography (the effective orifice area) introduce additional obscuring factors in the attempt to compare hemodynamic performance data of different stented tissue valves. We analyzed the true dimensions of different tissue prostheses and the manufacturer-suggested sizing strategies in relation to published effective orifice areas. We have demonstrated how sizing and implantation strategy have much greater impact on postoperative valve hemodynamics than valve brand or type. In addition, our findings may explain the different opinions regarding valve hemodynamics of different tissue valves. PMID:21703637

  8. Hemodynamic monitoring of organ donors: a novel use of the esophageal echo-Doppler probe.

    PubMed

    Cipolla, James; Stawicki, Stanislaw; Spatz, Deneen

    2006-06-01

    The esophageal Doppler monitoring (EDM) technology is well described in the literature. As it evolved over the last several years, the use of EDM has found expanded indications in various clinical settings. One of the areas where EDM has not been studied extensively is its use during optimization of organ donors before organ procurement. Close hemodynamic monitoring has become essential in the era of increasing use of extended organ donors. We present six cases of successful EDM use during preorgan procurement resuscitation of organ donors. Despite labile hemodynamics in the majority of these cases, EDM-guided optimization of resuscitative endpoints allowed successful organ procurements and transplants, including 12 kidneys, 6 livers, 3 hearts, 2 pancreases, and 2 lungs. The EDM technology is noninvasive, technically easy, and less expensive than the traditional pulmonary artery catheter. Other potential benefits of the EDM include its portability and possibility of deployment in any setting by trained organ procurement personnel or critical care nursing staff. In conclusion, successful organ procurement can be facilitated by the use of EDM technology in hemodynamically labile organ donor patients.

  9. [HEMODYNAMIC CHILDREN WITH ISOLATED ANOMALOUS CHORDS OF THE LEFT VENTRICLE DEPENDING ON LOCATION AND QUANTITY].

    PubMed

    Kondrashova, V G

    2015-01-01

    A total of 156 children group (children born to parents exposed to the Chernobyl disaster), in which, according to Doppler echocardiography, revealed isolated abnormal chords of the left ventricle (AHLV). Analysis of morphometric parameters and central hemodynamics conducted according to the localization AHLV. Found that concomitant localization AHLV at the threshold of the number of the most influencing change morphoinetric indicators and central hemodynamics. Condition of systemic circulation indicates a decline in their adaptive capacity of the cardiovascular system due to changes in the dynamics and power of the heartbeat. The decrease in stroke volume, stroke and cardiac index suggests hypokinetic type of organization of central hemodynamics, which can be considered an early sign of stress features of the heart and blood vessels. In this subgroup of children revealed significant changes in transmitral flow, indicating the initiation they have diastolic dysfunc tion. When the number of prethreshold AHLV most pronounced changes were found in the middle of their localization. Almost a third of children in this subgroup with individual assessment also revealed signs of initiation of diastolic dysfunction. PMID:27089709

  10. Jogging Therapy for Hikikomori Social Withdrawal and Increased Cerebral Hemodynamics: A Case Report.

    PubMed

    Nishida, Masaki; Kikuchi, Senichiro; Fukuda, Kazuhito; Kato, Satoshi

    2016-01-01

    Severe social withdrawal, called hikikomori, has drawn increased public attention. However, an optimal clinical approach and strategy of treatment has not been well established. Here, we report a case of hikikomori for which an exercise intervention using jogging therapy was effective, showing cerebral hemodynamic improvement. The patient was a 20 year old Japanese male who was hospitalized in order to evaluate and treat severe social withdrawal. Although depressive and anxiety symptoms partially subsided with sertraline alone, social withdrawal persisted due to a lack of self confidence. With his consent, we implemented exercise therapy with 30 minutes of jogging three times a week for three months. We did not change the pharmacotherapy, and his social withdrawal remarkably improved with continuous jogging exercise. Using near infrared spectroscopy to evaluate hemodynamic alteration, bilateral temporal hemodynamics considerably increased after the three-month jogging therapy. Regarding exercise therapy for mental illness, numerous studies have reported the effectiveness of exercise therapy for major depression. This case implied, however, that the applicability of exercise therapy is not limited to major depressive disorder. Jogging therapy may contribute to reinforcing self confidence associated with "resilience" in conjunction with neurophysiological modulation of neural networks. PMID:27346999

  11. Exploring diazepam's effect on hemodynamic responses of mouse brain tissue by optical spectroscopic imaging.

    PubMed

    Abookasis, David; Shochat, Ariel; Nesher, Elimelech; Pinhasov, Albert

    2014-07-01

    In this study, a simple duel-optical spectroscopic imaging apparatus capable of simultaneously determining relative changes in brain oxy-and deoxy-hemoglobin concentrations was used following administration of the anxiolytic compound diazepam in mice with strong dominant (Dom) and submissive (Sub) behavioral traits. Three month old mice (n = 30) were anesthetized and after 10 min of baseline imaging, diazepam (1.5 mg/kg) was administered and measurements were taken for 80 min. The mouse head was illuminated by white light based LED's and diffused reflected light passing through different channels, consisting of a bandpass filter and a CCD camera, respectively, was collected and analyzed to measure the hemodynamic response. This work's major findings are threefold: first, Dom and Sub animals showed statistically significant differences in hemodynamic response to diazepam administration. Secondly, diazepam was found to more strongly affect the Sub group. Thirdly, different time-series profiles were observed post-injection, which can serve as a possible marker for the groups' differentiation. To the best of our knowledge, this is the first report on the effects of an anxiolytic drug on brain hemodynamic responses in mice using diffused light optical imaging. PMID:25071958

  12. 4D subject-specific inverse modeling of the chick embryonic heart outflow tract hemodynamics.

    PubMed

    Goenezen, Sevan; Chivukula, Venkat Keshav; Midgett, Madeline; Phan, Ly; Rugonyi, Sandra

    2016-06-01

    Blood flow plays a critical role in regulating embryonic cardiac growth and development, with altered flow leading to congenital heart disease. Progress in the field, however, is hindered by a lack of quantification of hemodynamic conditions in the developing heart. In this study, we present a methodology to quantify blood flow dynamics in the embryonic heart using subject-specific computational fluid dynamics (CFD) models. While the methodology is general, we focused on a model of the chick embryonic heart outflow tract (OFT), which distally connects the heart to the arterial system, and is the region of origin of many congenital cardiac defects. Using structural and Doppler velocity data collected from optical coherence tomography, we generated 4D ([Formula: see text]) embryo-specific CFD models of the heart OFT. To replicate the blood flow dynamics over time during the cardiac cycle, we developed an iterative inverse-method optimization algorithm, which determines the CFD model boundary conditions such that differences between computed velocities and measured velocities at one point within the OFT lumen are minimized. Results from our developed CFD model agree with previously measured hemodynamics in the OFT. Further, computed velocities and measured velocities differ by [Formula: see text]15 % at locations that were not used in the optimization, validating the model. The presented methodology can be used in quantifications of embryonic cardiac hemodynamics under normal and altered blood flow conditions, enabling an in-depth quantitative study of how blood flow influences cardiac development.

  13. [HEMODYNAMIC CHILDREN WITH ISOLATED ANOMALOUS CHORDS OF THE LEFT VENTRICLE DEPENDING ON LOCATION AND QUANTITY].

    PubMed

    Kondrashova, V G

    2015-01-01

    A total of 156 children group (children born to parents exposed to the Chernobyl disaster), in which, according to Doppler echocardiography, revealed isolated abnormal chords of the left ventricle (AHLV). Analysis of morphometric parameters and central hemodynamics conducted according to the localization AHLV. Found that concomitant localization AHLV at the threshold of the number of the most influencing change morphoinetric indicators and central hemodynamics. Condition of systemic circulation indicates a decline in their adaptive capacity of the cardiovascular system due to changes in the dynamics and power of the heartbeat. The decrease in stroke volume, stroke and cardiac index suggests hypokinetic type of organization of central hemodynamics, which can be considered an early sign of stress features of the heart and blood vessels. In this subgroup of children revealed significant changes in transmitral flow, indicating the initiation they have diastolic dysfunc tion. When the number of prethreshold AHLV most pronounced changes were found in the middle of their localization. Almost a third of children in this subgroup with individual assessment also revealed signs of initiation of diastolic dysfunction.

  14. Prediction of hemodynamic changes towards PEEP titrations at different volemic levels using a minimal cardiovascular model.

    PubMed

    Starfinger, C; Chase, J G; Hann, C E; Shaw, G M; Lambert, P; Smith, B W; Sloth, E; Larsson, A; Andreassen, S; Rees, S

    2008-08-01

    A cardiovascular system model and parameter identification method have previously been validated for porcine experiments of induced pulmonary embolism and positive end-expiratory pressure (PEEP) titrations, accurately tracking all the main hemodynamic trends. In this research, the model and parameter identification process are further validated by predicting the effect of intervention. An overall population-specific rule linking specific model parameters to increases in PEEP is formulated to predict the hemodynamic effects on arterial pressure, pulmonary artery pressure and stroke volume. Hemodynamic changes are predicted for an increase from 0 to 10 cm H(2)O with median absolute percentage errors less than 7% (systolic pressures) and 13% (stroke volume). For an increase from 10 to 20 cm H(2)O median absolute percentage errors are less than 11% (systolic pressures) and 17% (stroke volume). These results validate the general applicability of such a rule, which is not pig-specific, but holds over for all analyzed pigs. This rule enables physiological simulation and prediction of patient response. Overall, the prediction accuracy achieved represents a further clinical validation of these models, methods and overall approach to cardiovascular diagnosis and therapy guidance.

  15. Effects of segmentation on patient-specific numerical simulation of cerebral aneurysm hemodynamics

    NASA Astrophysics Data System (ADS)

    Venugopal, Prem; Schmitt, Holger; Duckwiler, Gary R.; Valentino, Daniel J.

    2006-03-01

    One of the factors affecting the accuracy of patient-specific, imaging-based computational hemodynamic studies is the accuracy of geometric models created from medical images. In the present study we have investigated as to how accurate the geometric models should be in the context of cerebral aneurysms in order to obtain an accurate reproduction of intra-aneurysmal hemodynamics in individual patients using numerical simulations. Computed tomography angiography (CTA) images obtained for a patient-specific anterior communicating artery (ACoA) aneurysm and a patient-specific middle cerebral artery (MCA) aneurysm were used to construct the geometric models. For each aneurysm, two models were created, one using a different threshold value for image segmentation than the other. The average distance between the models was about the size of one in-plane pixel. It was found that for the MCA aneurysm, the simulated pressure and shear stress distributions for the two models were entirely different while for the ACoA aneurysm the mean pressure distribution obtained for the two models were similar, but the shear stress distributions were completely different. These results indicate that accurate reproduction of intra-aneurysmal hemodynamics would require the geometric reconstruction from medical images to be highly accurate.

  16. Application of near-infrared spectroscopy to measurement of hemodynamic signals accompanying stimulated saliva secretion.

    PubMed

    Sato, Hiroki; Obata, Akiko N; Moda, Ichiro; Ozaki, Kazutaka; Yasuhara, Takaomi; Yamamoto, Yukari; Kiguchi, Masashi; Maki, Atsushi; Kubota, Kisou; Koizumi, Hideaki

    2011-04-01

    We aim to test the feasibility of using near-infrared spectroscopy (NIRS) for indirect measurement of human saliva secretion in response to taste stimuli for potential application to organoleptic testing. We use an NIRS system to measure extracranial hemodynamics (Hb-signals around the temples) of healthy participants when taste stimuli are taken in their mouths. First, the Hb-signals and volume of expelled saliva (stimulated by distilled-water or sucrose-solution intake) are simultaneously measured and large Hb-signal changes in response to the taste stimuli (Hb-responses) are found. Statistical analysis show that both the Hb response and saliva volume are larger for the sucrose solution than for the distilled water with a significant correlation between them (r = 0.81). The effects of swallowing on the Hb-signals are investigated. Similar Hb responses, differing from the sucrose solution and distilled water, are obtained even though the participants swallow the mouth contents. Finally, functional magnetic resonance imaging is used to identify possible sources of the Hb signals corresponding to salivation. Statistical analysis indicates similar responses in the extracranial regions, mainly around the middle meningeal artery. In conclusion, the identified correlation between extracranial hemodynamics and the saliva volume suggests that NIRS is applicable to the measurement of hemodynamic signals accompanying stimulated saliva secretion.

  17. [Analysis and computational fluid dynamics simulation of hemodynamic influences caused by splenic vein thrombosis].

    PubMed

    Zhou, Hongyu; Gong, Peiyun; Du, Xuesen; Wang, Meng

    2015-02-01

    This paper aims to analyze the impact of splenic vein thrombosis (SVT) on the hemodynamic parameters in hepatic portal vein system. Based on computed tomography (CT) images of a patient with portal hypertension and commercial software MIMICS, the patient's portal venous system model was reconstructed. Color Doppler ultrasound method was used to measure the blood flow velocity in portal vein system and then the blood flow velocities were used as the inlet boundary conditions of simulation. By using the computational fluid dynamics (CFD) method, we simulated the changes of hemodynamic parameters in portal venous system with and without splenic vein thrombosis and analyzed the influence of physiological processes. The simulation results reproduced the blood flow process in portal venous system and the results showed that the splenic vein thrombosis caused serious impacts on hemodynamics. When blood flowed through the thrombosis, blood pressure reduced, flow velocity and wall shear stress increased. Flow resistance increased, blood flow velocity slowed down, the pressure gradient and wall shear stress distribution were more uniform in portal vein. The blood supply to liver decreased. Splenic vein thrombosis led to the possibility of forming new thrombosis in portal vein and surroundings.

  18. Coronary artery bypass grafting hemodynamics and anastomosis design: a biomedical engineering review.

    PubMed

    Ghista, Dhanjoo N; Kabinejadian, Foad

    2013-01-01

    In this paper, coronary arterial bypass grafting hemodynamics and anastomosis designs are reviewed. The paper specifically addresses the biomechanical factors for enhancement of the patency of coronary artery bypass grafts (CABGs). Stenosis of distal anastomosis, caused by thrombosis and intimal hyperplasia (IH), is the major cause of failure of CABGs. Strong correlations have been established between the hemodynamics and vessel wall biomechanical factors and the initiation and development of IH and thrombus formation. Accordingly, several investigations have been conducted and numerous anastomotic geometries and devices have been designed to better regulate the blood flow fields and distribution of hemodynamic parameters and biomechanical factors at the distal anastomosis, in order to enhance the patency of CABGs. Enhancement of longevity and patency rate of CABGs can eliminate the need for re-operation and can significantly lower morbidity, and thereby reduces medical costs for patients suffering from coronary stenosis. This invited review focuses on various endeavors made thus far to design a patency-enhancing optimized anastomotic configuration for the distal junction of CABGs.

  19. Coronary artery bypass grafting hemodynamics and anastomosis design: a biomedical engineering review

    PubMed Central

    2013-01-01

    In this paper, coronary arterial bypass grafting hemodynamics and anastomosis designs are reviewed. The paper specifically addresses the biomechanical factors for enhancement of the patency of coronary artery bypass grafts (CABGs). Stenosis of distal anastomosis, caused by thrombosis and intimal hyperplasia (IH), is the major cause of failure of CABGs. Strong correlations have been established between the hemodynamics and vessel wall biomechanical factors and the initiation and development of IH and thrombus formation. Accordingly, several investigations have been conducted and numerous anastomotic geometries and devices have been designed to better regulate the blood flow fields and distribution of hemodynamic parameters and biomechanical factors at the distal anastomosis, in order to enhance the patency of CABGs. Enhancement of longevity and patency rate of CABGs can eliminate the need for re-operation and can significantly lower morbidity, and thereby reduces medical costs for patients suffering from coronary stenosis. This invited review focuses on various endeavors made thus far to design a patency-enhancing optimized anastomotic configuration for the distal junction of CABGs. PMID:24330653

  20. The hemodynamics of human septic shock relate to circulating innate immunity factors.

    PubMed

    Hartemink, Koen J; Groeneveld, A B Johan

    2010-01-01

    The role of innate immunity, e.g., complement activation and cytokine release in the hemodynamic alterations in the course of human septic shock is largely unknown. We prospectively studied 14 consecutive septic shock patients with a pulmonary artery catheter in place. For 3 days after admission, hemodynamic variables and plasma levels of C3a, a product of complement activation, and interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) were measured 6-hourly. Doses of vasoactive drugs were recorded. Of the 14 patients, 8 died in the ICU. Patients had a hyperdynamic circulation with tachycardia, mild hypotension, increased cardiac index, peripheral vasodilation and myocardial depression. C3a, IL-6 and TNF-α plasma levels were supranormal in 123 of 138 (89%), 132 of 138 (96%) and 83 of 111 (75%) measurements, respectively. Independently of blood culture results, treatment with vasoactive drugs and outcome, mean arterial blood pressure and systemic vascular resistance index were lower when IL-6 levels were higher and left ventricular function was less depressed when C3a levels were higher in the course of septic shock. The TNF-α levels did not invariably relate to peripheral vascular and myocardial function parameters. Our serial observations suggest that, in human septic shock, peripheral vasodilation is most strongly and independently, of all inflammatory factors, associated with IL-6 release, whereas complement activation partly offsets the myocardial depression of the syndrome. Innate immunity factors may thus differ in their contribution to the course of hemodynamic abnormalities of septic shock.

  1. An integrative model of the cardiovascular system coupling heart cellular mechanics with arterial network hemodynamics.

    PubMed

    Kim, Young-Tae; Lee, Jeong Sang; Youn, Chan-Hyun; Choi, Jae-Sung; Shim, Eun Bo

    2013-08-01

    The current study proposes a model of the cardiovascular system that couples heart cell mechanics with arterial hemodynamics to examine the physiological role of arterial blood pressure (BP) in left ventricular hypertrophy (LVH). We developed a comprehensive multiphysics and multiscale cardiovascular model of the cardiovascular system that simulates physiological events, from membrane excitation and the contraction of a cardiac cell to heart mechanics and arterial blood hemodynamics. Using this model, we delineated the relationship between arterial BP or pulse wave velocity and LVH. Computed results were compared with existing clinical and experimental observations. To investigate the relationship between arterial hemodynamics and LVH, we performed a parametric study based on arterial wall stiffness, which was obtained in the model. Peak cellular stress of the left ventricle and systolic blood pressure (SBP) in the brachial and central arteries also increased; however, further increases were limited for higher arterial stiffness values. Interestingly, when we doubled the value of arterial stiffness from the baseline value, the percentage increase of SBP in the central artery was about 6.7% whereas that of the brachial artery was about 3.4%. It is suggested that SBP in the central artery is more critical for predicting LVH as compared with other blood pressure measurements.

  2. Lower stroke risk with lower blood pressure in hemodynamic cerebral ischemia

    PubMed Central

    Clarke, William R.; Grubb, Robert L.; Videen, Tom O.; Adams, Harold P.; Derdeyn, Colin P.

    2014-01-01

    Objective: To determine whether strict blood pressure (BP) control is the best medical management for patients with symptomatic carotid artery occlusion and hemodynamic cerebral ischemia. Methods: In this prospective observational cohort study, we analyzed data from 91 participants in the nonsurgical group of the Carotid Occlusion Surgery Study (COSS) who had recent symptomatic internal carotid artery occlusion and hemodynamic cerebral ischemia manifested by ipsilateral increased oxygen extraction fraction. The target BP goal in COSS was ≤130/85 mm Hg. We compared the occurrence of ipsilateral ischemic stroke during follow-up in the 41 participants with mean BP ≤130/85 mm Hg to the remaining 50 with higher BP. Results: Of 16 total ipsilateral ischemic strokes that occurred during follow-up, 3 occurred in the 41 participants with mean follow-up BP of ≤130/85 mm Hg, compared to 13 in the remaining 50 participants with mean follow-up BP >130/85 mm Hg (hazard ratio 3.742, 95% confidence interval 1.065–13.152, log-rank p = 0.027). Conclusion: BPs ≤130/85 mm Hg were associated with lower subsequent stroke risk in these patients. Classification of evidence: This study provides Class III evidence that control of hypertension ≤130/85 mm Hg is associated with a reduced risk of subsequent ipsilateral ischemic stroke in patients with recently symptomatic carotid occlusion and hemodynamic cerebral ischemia (increased oxygen extraction fraction). PMID:24532276

  3. Hemodynamic consequences of severe lactic acidosis in shock states: from bench to bedside.

    PubMed

    Kimmoun, Antoine; Novy, Emmanuel; Auchet, Thomas; Ducrocq, Nicolas; Levy, Bruno

    2015-04-09

    Lactic acidosis is a very common biological issue for shock patients. Experimental data clearly demonstrate that metabolic acidosis, including lactic acidosis, participates in the reduction of cardiac contractility and in the vascular hyporesponsiveness to vasopressors through various mechanisms. However, the contributions of each mechanism responsible for these deleterious effects have not been fully determined and their respective consequences on organ failure are still poorly defined, particularly in humans. Despite some convincing experimental data, no clinical trial has established the level at which pH becomes deleterious for hemodynamics. Consequently, the essential treatment for lactic acidosis in shock patients is to correct the cause. It is unknown, however, whether symptomatic pH correction is beneficial in shock patients. The latest Surviving Sepsis Campaign guidelines recommend against the use of buffer therapy with pH ≥7.15 and issue no recommendation for pH levels <7.15. Furthermore, based on strong experimental and clinical evidence, sodium bicarbonate infusion alone is not recommended for restoring pH. Indeed, bicarbonate induces carbon dioxide generation and hypocalcemia, both cardiovascular depressant factors. This review addresses the principal hemodynamic consequences of shock-associated lactic acidosis. Despite the lack of formal evidence, this review also highlights the various adapted supportive therapy options that could be putatively added to causal treatment in attempting to reverse the hemodynamic consequences of shock-associated lactic acidosis.

  4. Comparative effects of enalapril and nifedipine on renal hemodynamics in hypertensive renal allograft recipients.

    PubMed

    Abu-Romeh, S H; el-Khatib, D; Rashid, A; Patel, M; Osman, N; Fayyad, M; Scheikhoni, A; Higazi, A S

    1992-04-01

    The comparative effects of enalapril (E) and nifedipine (N) on renal hemodynamics were assessed in twenty-two moderately hypertensive, cadaveric renal transplant patients who were maintaining stable renal function. Fourteen patients were on cyclosporin (CSA) and eight were receiving azathioprine with prednisolone (AZA). In each patient effective renal plasma flow (ERPF) was determined four times, first baseline, second with E, third as another baseline after a washout period, and fourth with N; and renal vascular resistance (RVR) was derived in each. ERPF and RVR were significantly compromised in the CSA group (202 +/- 55 ml/min and 65 +/- 18 mmHg/ml/min) compared to the AZA group (302 +/- 99 and 43 +/- 15 respectively). During E therapy, RVR further increased in the CSA group to 82 +/- 37 while it decreased in the AZA group to 31 +/- 7 (both changes were significant when compared to their respective baseline values). N, on the other hand, only significantly lowered RVR in the AZA group. Furthermore, two patients, one from each group, developed acute reversible renal failure shortly after E therapy. However, both agents were effective in lowering blood pressure to a comparable degree in both groups. In conclusion, our data showed a somewhat less favourable renal hemodynamic response to short-term enalapril therapy in hypertensive renal transplant patients maintained on CSA. However, the significance of such hemodynamic changes for long-term renal function remains uncertain.

  5. MRI-based Protocol to Characterize the Relationship Between Bicuspid Aortic Valve Morphology and Hemodynamics.

    PubMed

    Mirabella, Lucia; Barker, Alex J; Saikrishnan, Neelakantan; Coco, Elizabeth R; Mangiameli, Daniel J; Markl, Michael; Yoganathan, Ajit P

    2015-08-01

    Bicuspid aortic valve (BAV) is the most common congenital heart defect and can lead to severe complications. Many studies have been conducted to evaluate the potential of geometric and hemodynamic biomarkers to predict BAV-related aortopathy. This work proposes a novel semi-automatic protocol to characterize geometry and hemodynamics of aorta and aortic valve based on 2D cine and 4D flow MRI data. The protocol was applied to 12 BAV and 12 control subjects. Statistical differences between the groups were identified and linear regression models were investigated to elucidate the potential of this protocol to investigate the risk of disease progression. Statistical differences between the groups were found for orifice eccentricity, aorta diameter, velocity, jet angle and flow displacement. Key findings of the regression analysis include the association in the proximal ascending aorta between aorta diameter and mean velocity (negative), jet angle (positive) and flow displacement (positive), in the combined cohort. Positive association between flow displacement in the proximal aorta and orifice jet angle in TAV subjects was found. This study represents a pilot application of a protocol for standardized assessment of aortic geometry and hemodynamics associated with BAV disease. Its limited need for user input is advantageous for large cohort studies. PMID:25533768

  6. Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise.

    PubMed

    Henry, Brad; Zhao, Mingjun; Shang, Yu; Uhl, Timothy; Thomas, D Travis; Xenos, Eleftherios S; Saha, Sibu P; Yu, Guoqiang

    2015-12-01

    Occlusion calibrations and gating techniques have been recently applied by our laboratory for continuous and absolute diffuse optical measurements of forearm muscle hemodynamics during handgrip exercises. The translation of these techniques from the forearm to the lower limb is the goal of this study as various diseases preferentially affect muscles in the lower extremity. This study adapted a hybrid near-infrared spectroscopy and diffuse correlation spectroscopy system with a gating algorithm to continuously quantify hemodynamic responses of medial gastrocnemius during plantar flexion exercises in 10 healthy subjects. The outcomes from optical measurement include oxy-, deoxy-, and total hemoglobin concentrations, blood oxygen saturation, and relative changes in blood flow (rBF) and oxygen consumption rate (rV̇O2). We calibrated rBF and rV̇O2 profiles with absolute baseline values of BF and V̇O2 obtained by venous and arterial occlusions, respectively. Results from this investigation were comparable to values from similar studies. Additionally, significant correlation was observed between resting local muscle BF measured by the optical technique and whole limb BF measured concurrently by a strain gauge venous plethysmography. The extensive hemodynamic and metabolic profiles during exercise will allow for future comparison studies to investigate the diagnostic value of hybrid technologies in muscles affected by disease. PMID:26720871

  7. Acutely altered hemodynamics following venous obstruction in the early chick embryo.

    PubMed

    Stekelenburg-de Vos, Sandra; Ursem, Nicolette T C; Hop, Wim C J; Wladimiroff, Juriy W; Gittenberger-de Groot, Adriana C; Poelmann, Robert E

    2003-03-01

    In the venous clip model specific cardiac malformations are induced in the chick embryo by obstructing the right lateral vitelline vein with a microclip. Clipping alters venous return and intracardiac laminar blood flow patterns, with secondary effects on the mechanical load of the embryonic myocardium. We investigated the instantaneous effects of clipping the right lateral vitelline vein on hemodynamics in the stage-17 chick embryo. 32 chick embryos HH 17 were subdivided into venous clipped (N=16) and matched control embryos (N=16). Dorsal aortic blood flow velocity was measured with a 20 MHz pulsed Doppler meter. A time series of eight successive measurements per embryo was made starting just before clipping and ending 5h after clipping. Heart rate, peak systolic velocity, time-averaged velocity, peak blood flow, mean blood flow, peak acceleration and stroke volume were determined. All hemodynamic parameters decreased acutely after venous clipping and only three out of seven parameters (heart rate, time-averaged velocity and mean blood flow) showed a recovery to baseline values during the 5h study period. We conclude that the experimental alteration of venous return has major acute effects on hemodynamics in the chick embryo. These effects may be responsible for the observed cardiac malformations after clipping.

  8. Reduced Prefrontal Cortex Hemodynamic Response in Adults with Methamphetamine Induced Psychosis: Relevance for Impulsivity

    PubMed Central

    Yamamuro, Kazuhiko; Kimoto, Sohei; Iida, Junzo; Kishimoto, Naoko; Nakanishi, Yoko; Tanaka, Shohei; Ota, Toyosaku; Makinodan, Manabu; Kishimoto, Toshifumi

    2016-01-01

    Patients with methamphetamine abuse/dependence often exhibit high levels of impulsivity, which may be associated with the structural abnormalities and functional hypoactivities observed in the frontal cortex of these subjects. Although near-infrared spectroscopy (NIRS) is a simple and non-invasive method for characterizing the clinical features of various psychiatric illnesses, few studies have used NIRS to directly investigate the association between prefrontal cortical activity and inhibitory control in patients with methamphetamine-induced psychosis (MAP). Using a 24-channel NIRS system, we compared hemodynamic responses during the Stroop color-word task in 14 patients with MAP and 21 healthy controls matched for age, sex and premorbid IQ. In addition, we used the Barrett Impulsivity Scale-11 (BIS-11) to assess impulsivity between subject groups. The MAP group exhibited significantly less activation in the anterior and frontopolar prefrontal cortex accompanied by lower Stroop color-word task performance, compared with controls. Moreover, BIS-11 scores were significantly higher in the MAP group, and were negatively correlated with the hemodynamic responses in prefrontal cortex. Our data suggest that reduced hemodynamic responses in the prefrontal cortex might reflect higher levels of impulsivity in patients with MAP, providing new insights into disrupted inhibitory control observed in MAP. PMID:27050450

  9. Hemodynamic effects of encainide in patients with ventricular arrhythmia and poor ventricular function

    SciTech Connect

    Sami, M.H.; Derbekyan, V.A.; Lisbona, R.

    1983-09-01

    Gated cardiac scanning was used to evaluate the hemodynamic effects of encainide in 19 patients (1 woman) with complex ventricular arrhythmia and depressed left ventricular (LV) function (ejection fraction less than 45%). Patients were 36 to 80 years old (average 61). All were candidates for long-term encainide therapy after having failed with currently available antiarrhythmics. Sixty-three percent had congestive heart failure before they received encainide. All were evaluated in the hospital before encainide therapy by a gated cardiac scan performed at least 3 days after discontinuing all antiarrhythmic drugs. Patients received oral encainide in doses of 75 to 200 mg. Gated cardiac scans were repeated 1 to 2 weeks later when an 80% reduction in frequency of premature ventricular complexes was observed on a 24-hour Holter recording. No patient had worsening of congestive heart failure during encainide therapy. Encainide did not significantly affect ejection fraction, which averaged 22 +/- 10% before and 25 +/- 14% (SD) after encainide (difference not significant (NS)). Other hemodynamic variables, including heart rate, blood pressure, stroke volume and end-diastolic volume, remained unchanged during encainide therapy. Digoxin blood levels in 10 patients averaged 1.04 +/- 0.43 before and 1.22 +/- 0.47 mg/ml (NS) during encainide therapy. Thus, encainide given orally in clinically effective doses does not appear to have significant hemodynamic effects in patients with ventricular arrhythmia and depressed LV function.

  10. Noninvasive optical evaluation of low frequency oscillations in prefrontal cortex hemodynamics during verbal working memory

    NASA Astrophysics Data System (ADS)

    Li, Ting; Zhao, Yue; Li, Kai; Sun, Yunlong

    2014-03-01

    The low frequency oscillation (LFO) around 0.1 Hz has been observed recently in cerebral hemodynamic signals during rest/sleep, enhanced breathing, and head- up-tilting, showing that cerebral autoregulation can be accessed by LFOs. However, many brain function researches require direct measurement of LFOs during specified brain function activities. This pilot study explored using near-infrared spectroscopy/imaging (NIRS) to noninvasively and simultaneously detect LFOs of prefrontal cerebral hemodynamics (i.e., oxygenated/deoxygenated/total hemoglobin concentration: △[oxy-Hb]/ △[deoxy-Hb]/ △[tot-Hb]) during N-back visual verbal working memory task. The LFOs were extracted from the measured variables using power spectral analysis. We found the brain activation sites struck clear LFOs while other sites did not. The LFO of △[deoxy-Hb] acted as a negative pike and ranged in (0.05, 0.1) Hz, while LFOs of △[oxy-Hb] and △[tot-Hb] acted as a positive pike and ranged in (0.1, 0.15) Hz. The amplitude difference and frequency lag between △[deoxy-Hb] and △[oxy-Hb]/ △[tot-Hb] produced a more focused and sensitive activation map compare to hemodynamic amplitude-quantified activation maps. This study observed LFOs in brain activities and showed strong potential of LFOs in accessing brain functions.

  11. Evolution from electrophysiologic to hemodynamic monitoring: the story of left atrial and pulmonary artery pressure monitors

    PubMed Central

    Mooney, Deirdre M.; Fung, Erik; Doshi, Rahul N.; Shavelle, David M.

    2015-01-01

    Heart failure (HF) is a costly, challenging and highly prevalent medical condition. Hospitalization for acute decompensation is associated with high morbidity and mortality. Despite application of evidence-based medical therapies and technologies, HF remains a formidable challenge for virtually all healthcare systems. Repeat hospitalizations for acute decompensated HF (ADHF) can have major financial impact on institutions and resources. Early and accurate identification of impending ADHF is of paramount importance yet there is limited high quality evidence or infrastructure to guide management in the outpatient setting. Historically, ADHF was identified by physical exam findings or invasive hemodynamic monitoring during a hospital admission; however, advances in medical microelectronics and the advent of device-based diagnostics have enabled long-term ambulatory monitoring of HF patients in the outpatient setting. These monitors have evolved from piggybacking on cardiac implantable electrophysiologic devices to standalone implantable hemodynamic monitors that transduce left atrial or pulmonary artery pressures as surrogate measures of left ventricular filling pressure. As technology evolves, devices will likely continue to miniaturize while their capabilities grow. An important, persistent challenge that remains is developing systems to translate the large volumes of real-time data, particularly data trends, into actionable information that leads to appropriate, safe and timely interventions without overwhelming outpatient cardiology and general medical practices. Future directions for implantable hemodynamic monitors beyond their utility in heart failure may include management of other major chronic diseases such as pulmonary hypertension, end stage renal disease and portal hypertension. PMID:26500556

  12. Occipital and orbitofrontal hemodynamics during naturally paced reading: an fNIRS study.

    PubMed

    Hofmann, Markus J; Dambacher, Michael; Jacobs, Arthur M; Kliegl, Reinhold; Radach, Ralph; Kuchinke, Lars; Plichta, Michael M; Fallgatter, Andreas J; Herrmann, Martin J

    2014-07-01

    Humans typically read at incredibly fast rates, because they predict likely occurring words from a given context. Here, we used functional near-infrared spectroscopy (fNIRS) to track the ultra-rapid hemodynamic responses of words presented every 280 ms in a naturally paced sentence context. We found a lower occipital deoxygenation to unpredictable than to predictable words. The greater hemodynamic responses to unexpected words suggest that the visual features of expected words have been pre-activated previous to stimulus presentation. Second, we tested opposing theoretical proposals about the role of the medial orbitofrontal cortex (OFC): Either OFC may respond to the breach of expectation; or OFC is activated when the present stimulus matches the prediction. A significant interaction between word frequency and predictability indicated OFC responses to breaches of expectation for low- but not for high-frequency words: OFC is sensitive to both, bottom-up processing as mediated by word frequency, as well as top-down predictions. Particularly, when a rare word is unpredictable, OFC becomes active. Finally, we discuss how a high temporal resolution can help future studies to disentangle the hemodynamic responses of single trials in such an ultra-rapid event succession as naturally paced reading.

  13. Group-level impacts of within- and between-subject hemodynamic variability in fMRI.

    PubMed

    Badillo, Solveig; Vincent, Thomas; Ciuciu, Philippe

    2013-11-15

    Inter-subject fMRI analyses have specific issues regarding the reliability of the results concerning both the detection of brain activation patterns and the estimation of the underlying dynamics. Among these issues lies the variability of the hemodynamic response function (HRF), that is usually accounted for using functional basis sets in the general linear model context. Here, we use the joint detection-estimation approach (JDE) (Makni et al., 2008; Vincent et al., 2010) which combines regional nonparametric HRF inference with spatially adaptive regularization of activation clusters to avoid global smoothing of fMRI images. We show that the JDE-based inference brings a significant improvement in statistical sensitivity for detecting evoked activity in parietal regions. In contrast, the canonical HRF associated with spatially adaptive regularization is more sensitive in other regions, such as motor cortex. This different regional behavior is shown to reflect a larger discrepancy of HRF with the canonical model. By varying parallel imaging acceleration factor, SNR-specific region-based hemodynamic parameters (activation delay and duration) were extracted from the JDE inference. Complementary analyses highlighted their significant departure from the canonical parameters and the strongest between-subject variability that occurs in the parietal region, irrespective of the SNR value. Finally, statistical evidence that the fluctuation of the HRF shape is responsible for the significant change in activation detection performance is demonstrated using paired t-tests between hemodynamic parameters inferred by GLM and JDE. PMID:23735261

  14. Social cognition and prefrontal hemodynamic responses during a working memory task in schizophrenia

    PubMed Central

    Pu, Shenghong; Nakagome, Kazuyuki; Yamada, Takeshi; Itakura, Masashi; Yamanashi, Takehiko; Yamada, Sayaka; Masai, Mieko; Miura, Akihiko; Yamauchi, Takahira; Satake, Takahiro; Iwata, Masaaki; Nagata, Izumi; Roberts, David L.; Kaneko, Koichi

    2016-01-01

    Social cognition is an important determinant of functional impairment in schizophrenia, but its relationship with the prefrontal functional abnormalities associated with the condition is still unclear. The present study aimed to explore the relationship between social cognition and prefrontal function in patients with schizophrenia using 52-channel near-infrared spectroscopy (NIRS). Twenty-six patients with schizophrenia and 26 age-, gender-, and intelligence quotient-matched healthy controls (HCs) participated in the study. Hemodynamic responses in the prefrontal and superior temporal cortical regions were assessed during a working memory task using NIRS. Social cognition was assessed using the Social Cognition Screening Questionnaire (SCSQ). The observed hemodynamic responses were significantly reduced in the lateral prefrontal cortex (PFC), the frontopolar cortex, and temporal regions in subjects with schizophrenia compared to HCs. Additionally, lateral PFC hemodynamic responses assessed during the working memory task demonstrated a strong positive correlation with the SCSQ theory of mind (ToM) subscale score even after controlling for working memory performance. These results suggest that ToM integrity is closely related to lateral PFC functional abnormalities found in patients with schizophrenia. In addition, this study provides evidence to suggest that NIRS could be used to identify biomarkers of social cognition function in subjects with schizophrenia. PMID:26928254

  15. Jogging Therapy for Hikikomori Social Withdrawal and Increased Cerebral Hemodynamics: A Case Report.

    PubMed

    Nishida, Masaki; Kikuchi, Senichiro; Fukuda, Kazuhito; Kato, Satoshi

    2016-01-01

    Severe social withdrawal, called hikikomori, has drawn increased public attention. However, an optimal clinical approach and strategy of treatment has not been well established. Here, we report a case of hikikomori for which an exercise intervention using jogging therapy was effective, showing cerebral hemodynamic improvement. The patient was a 20 year old Japanese male who was hospitalized in order to evaluate and treat severe social withdrawal. Although depressive and anxiety symptoms partially subsided with sertraline alone, social withdrawal persisted due to a lack of self confidence. With his consent, we implemented exercise therapy with 30 minutes of jogging three times a week for three months. We did not change the pharmacotherapy, and his social withdrawal remarkably improved with continuous jogging exercise. Using near infrared spectroscopy to evaluate hemodynamic alteration, bilateral temporal hemodynamics considerably increased after the three-month jogging therapy. Regarding exercise therapy for mental illness, numerous studies have reported the effectiveness of exercise therapy for major depression. This case implied, however, that the applicability of exercise therapy is not limited to major depressive disorder. Jogging therapy may contribute to reinforcing self confidence associated with "resilience" in conjunction with neurophysiological modulation of neural networks.

  16. Hemodynamic Changes in Treated Cerebral Aneurysms and Correlations with Long-Term Outcomes

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Barbour, Michael; Levitt, Michael; Kim, Louis; Aliseda, Alberto

    2014-11-01

    The hemodynamic conditions in patients with cerebral aneurysms undergoing treatment, e.g. flow diverting stents or coil embolization, are investigated via computational simulations. Patient-specific 3D models of the vasculature are derived from rotational angiography. Patient-specific flow and pressure boundary conditions are prescribed utilizing intravascular pressure and velocity measurements. Pre-treatment and immediate post-treatment hemodynamics are studied in eight cases so as to ascertain the effect of the treatment on the intra-aneurysmal flow and wall shear stress. We hypothesize that larger reductions in intra-aneurysmal inflow and wall shear stress after treatment are correlated with an increased likelihood of aneurysmal occlusion and treatment success. Results indicate reductions of the intra-aneurysmal inflow and wall shear stress in all cases. Preliminary clinical six-month follow-up data, assessing if the treatment has been successful, shows that the cases with a persistent aneurysm had a smaller reduction in inflow and wall shear stress magnitude in the immediate post-treatment conditions. This suggests that CFD can be used to quantify a treatment's probability of success by computing the change in pre-and-post-treatment hemodynamics in cerebral aneurysms. NIH-NINDS.

  17. Accuracy of Computational Cerebral Aneurysm Hemodynamics Using Patient-Specific Endovascular Measurements

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Levitt, Michael; Barbour, Michael; Mourad, Pierre; Kim, Louis; Aliseda, Alberto

    2013-11-01

    We study the hemodynamic conditions in patients with cerebral aneurysms through endovascular measurements and computational fluid dynamics. Ten unruptured cerebral aneurysms were clinically assessed by three dimensional rotational angiography and an endovascular guidewire with dual Doppler ultrasound transducer and piezoresistive pressure sensor at multiple peri-aneurysmal locations. These measurements are used to define boundary conditions for flow simulations at and near the aneurysms. The additional in vivo measurements, which were not prescribed in the simulation, are used to assess the accuracy of the simulated flow velocity and pressure. We also performed simulations with stereotypical literature-derived boundary conditions. Simulated velocities using patient-specific boundary conditions showed good agreement with the guidewire measurements, with no systematic bias and a random scatter of about 25%. Simulated velocities using the literature-derived values showed a systematic over-prediction in velocity by 30% with a random scatter of about 40%. Computational hemodynamics using endovascularly-derived patient-specific boundary conditions have the potential to improve treatment predictions as they provide more accurate and precise results of the aneurysmal hemodynamics. Supported by an R03 grant from NIH/NINDS

  18. MRI-based protocol to characterize the relationship between bicuspid aortic valve morphology and hemodynamics

    PubMed Central

    Mirabella, Lucia; Barker, Alex J.; Saikrishnan, Neelakantan; Coco, Elizabeth R.; Mangiameli, Daniel J.; Markl, Michael; Yoganathan, Ajit P.

    2015-01-01

    Bicuspid aortic valve (BAV) is the most common congenital heart defect and can lead to severe complications. Many studies have been conducted to evaluate the potential of geometric and hemodynamic biomarkers to predict BAV-related aortopathy. This work proposes a novel semi-automatic protocol to characterize geometry and hemodynamics of aorta and aortic valve based on 2D cine and 4D Flow MRI data. The protocol was applied to 12 BAV and 12 control subjects. Statistical differences between the groups were identified and linear regression models were investigated to elucidate the potential of this protocol to investigate the risk of disease progression. Statistical differences between the groups were found for orifice eccentricity, aorta diameter, velocity, jet angle and flow displacement. Key findings of the regression analysis include the association in the proximal ascending aorta between aorta diameter and mean velocity (negative), jet angle (positive) and flow displacement (positive), in the combined cohort. Positive association between flow displacement in the proximal aorta and orifice jet angle in TAV subjects was found. This study represents a pilot application of a protocol for standardized assessment of aortic geometry and hemodynamics associated with BAV disease. Its limited need for user input is advantageous for large cohort studies. PMID:25533768

  19. Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise

    NASA Astrophysics Data System (ADS)

    Henry, Brad; Zhao, Mingjun; Shang, Yu; Uhl, Timothy; Thomas, D. Travis; Xenos, Eleftherios S.; Saha, Sibu P.; Yu, Guoqiang

    2015-12-01

    Occlusion calibrations and gating techniques have been recently applied by our laboratory for continuous and absolute diffuse optical measurements of forearm muscle hemodynamics during handgrip exercises. The translation of these techniques from the forearm to the lower limb is the goal of this study as various diseases preferentially affect muscles in the lower extremity. This study adapted a hybrid near-infrared spectroscopy and diffuse correlation spectroscopy system with a gating algorithm to continuously quantify hemodynamic responses of medial gastrocnemius during plantar flexion exercises in 10 healthy subjects. The outcomes from optical measurement include oxy-, deoxy-, and total hemoglobin concentrations, blood oxygen saturation, and relative changes in blood flow (rBF) and oxygen consumption rate (rV˙O2). We calibrated rBF and rV˙O2 profiles with absolute baseline values of BF and V˙O2 obtained by venous and arterial occlusions, respectively. Results from this investigation were comparable to values from similar studies. Additionally, significant correlation was observed between resting local muscle BF measured by the optical technique and whole limb BF measured concurrently by a strain gauge venous plethysmography. The extensive hemodynamic and metabolic profiles during exercise will allow for future comparison studies to investigate the diagnostic value of hybrid technologies in muscles affected by disease.

  20. Characterization of pulmonary microcirculation according to hemodynamic changes with computed tomography

    NASA Astrophysics Data System (ADS)

    Choi, Byoung W.; Choe, Kyu O.; Kim, Hee-Joung; Cho, Bum K.; Chung, Kyung Y.; Kim, Se K.; Kim, Bong K.; Yang, In S.

    2002-04-01

    The common and important change of pulmonary hemodynamics is represented by increased or decreased pulmonary blood flow (PBF) and increased pulmonary vascular resistance (PVR). We made 3 hemodynamic models in 5 dogs, that is, increased and decreased PBF model and increased PVR model. CT perfusion scan was performed. Perfusion parameters including blood flow (BF), blood volume (BV), mean transit time (MTT), and maximal slope (MS) were analyzed. In normal state, blood flow was affected by gravity and dependent area showed higher BF, BV and lower MS, MTT than non-dependent area. First, decreased PBF model showed no significant change in BV and elongation of MTT. Secondly, increased PBF model showed slightly increased BV and decreased MTT. Thirdly, increased PVR model showed significant decrease of BF, BV, and MS and slight increase of MTT without statistical significance. However, it was noticeable that the distribution of MTT according to gravity in normal lung was completely reversed in increased PVR model. In conclusion, on the basis of our understanding of perfusion characteristic in normal state, we can detect and evaluate the abnormal regional hemodynamic change in lung. Predicting the change of pulmonary vascular resistance should be possible by thorough analysis of CT perfusion parameters.

  1. Device specific analysis of neonatal aortic outflow cannula jet flows for improved cardiopulmonary bypass hemodynamics

    NASA Astrophysics Data System (ADS)

    Menon, Prahlad; Sotiropoulos, Fotis; Undar, Akif; Pekkan, Kerem

    2011-11-01

    Hemodynamically efficient aortic outflow cannulae can provide high blood volume flow rates at low exit force during extracorporeal circulation in pediatric or neonatal cardiopulmonary bypass repairs. Furthermore, optimal hemolytic aortic insertion configurations can significantly reduce risk of post-surgical neurological complications and developmental defects in the young patient. The methodology and results presented in this study serve as a baseline for design of superior aortic outflow cannulae based on a novel paradigm of characterizing jet-flows at different flow regimes. In-silico evaluations of multiple cannula tips were used to delineate baseline hemodynamic performance of the popular pediatric cannula tips in an experimental cuboidal test-rig, using PIV. High resolution CFD jet-flow simulations performed for various cannula tips in the cuboidal test-rig as well as in-vivo insertion configurations have suggested the existence of optimal surgically relevant characteristics such as cannula outflow angle and insertion depth for improved hemodynamic performance during surgery. Improved cannula tips were designed with internal flow-control features for decreased blood damage and increased permissible flow rates.

  2. Hemodynamic and electrocardiographic effects of ioversol during cardiac angiography. Comparison with iopamidol and diatrizoate.

    PubMed

    Hirshfeld, J W; Wieland, J; Davis, C A; Giles, B D; Passione, D; Ray, M B; Ripley, N S

    1989-02-01

    We studied the hemodynamic and electrocardiographic responses to left ventriculography and coronary arteriography with three angiographic contrast agents. Two were nonionic agents (ioversol 32% iodine, 60 patients, and iopamidol 37% iodine, 30 patients). The third was a conventional ionic agent (diatrizoate 37% iodine, 30 patients). Cardiovascular hemodynamics and the electrocardiogram were recorded for 5 minutes after left ventricular injection and for 2 minutes after coronary injections. Following left ventriculography, diatrizoate caused a greater increase in cardiac output, left ventricular end diastolic pressure, and corrected QT interval while causing a greater decrease in arterial pressure than did either ioversol or iopamidol, which were indistinguishable from each other. Following left coronary arteriography, diatrizoate caused a significant decrease in heart rate, prolongation of the corrected QT interval, and increase in T wave amplitude. In contrast, neither ioversol nor iopamidol caused significant changes in any electrocardiographic parameters. Adverse reactions were more common with diatrizoate than with either ioversol or iopamidol. There were no recognizable differences in angiographic image quality among the three agents. We conclude that the angiographic performance of ioversol is equivalent to that of iopamidol and that both cause less hemodynamic and electrocardiographic disturbance than diatrizoate.

  3. 46 CFR Sec. 1 - Purpose.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 8 2011-10-01 2011-10-01 false Purpose. Sec. 1 Section 1 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION B-CONTROL AND UTILIZATION OF PORTS OPERATING CONTRACT Sec. 1 Purpose. This part prescribes the standard form of marine terminal contract to be entered into by the...

  4. Shoulder skin and muscle hemodynamics during backpack carriage.

    PubMed

    Mao, Clifford P; Macias, Brandon R; Hargens, Alan R

    2015-11-01

    The purpose of this study was to quantify the effects of loaded backpacks on shoulder muscle oxygenation, skin blood flow, and pain. We hypothesized that backpack load carriage is associated with lower shoulder muscle oxygenation and skin microvascular flow. Near-infrared spectroscopy quantified shoulder tissue oxygenation and laser Doppler flow measured skin microvascular flow. Eight adult volunteers donned a standard backpack without added load, 5 kg load, and 10 kg load for 5 min while standing. An 8 min rest period before each backpack donning condition ensured that all measured parameters returned to baseline. Data were analyzed using a repeated measures ANOVA and significance set at p < 0.05. Donning a 10 kg backpack significantly reduced shoulder muscle oxygenation by 22 ± 23% as compared to the empty backpack control condition (p = 0.023). In addition, a 10 kg backpack load reduced skin microvascular flow by 82 ± 22%, as compared to the empty backpack control condition (p = 0.024). Perceived pain was significantly higher when wearing the 10 kg backpack (level 4 on a 10-maximal pain scale) as compared to the empty backpack (0, 0-no pain) (p < 0.05). In conclusion, backpack loads of 10 kg decrease shoulder muscle oxygenation and skin microvascular flow. PMID:26154207

  5. Intracranial Hemodynamic Changes During Adult Moyamoya Disease Progression

    PubMed Central

    Kwag, Hyun-Jeong; Jeong, Dong-Wook; Lee, Suk Hoon; Kim, Dae Hyun

    2008-01-01

    Background and purpose This study evaluated the changes in blood flow velocity in the anterior and posterior intracranial circulations according to the progression of moyamoya disease in adult patients. Methods We evaluated Suzuki's angiographic stage and mean blood flow velocity (MBFV) changes in intracranial vessels from both sides in 19 adult moyamoya patients. We then analyzed the linearity of MBFV changes from early to late moyamoya stages in each intracranial vessel using piecewise linear regression models. Results The MBFV in the middle cerebral artery, terminal internal carotid artery, and anterior cerebral artery increased non linearly until stage III, and then decreased progressively up to stage VI. The ophthalmic artery also showed nonlinear velocity changes, with an increase in MBFV up to stage IV, followed by a decrease in MBFV up to stage VI. The MBFV of the basilar artery increased linearly from a normal velocity at an early moyamoya stage to a stenotic velocity at a late stage. There was no statistically significant regression model for the relationship between the MBFV in the posterior cerebral artery and moyamoya stage. Conclusions The nonlinear and/or linear MBFV changes associated with variable intracranial vessels might be useful in initial and follow-up evaluations of different stages of moyamoya disease. PMID:19513306

  6. Hemodynamic effects of dexmedetomidine in critically ill neonates and infants with heart disease.

    PubMed

    Lam, Francis; Bhutta, Adnan T; Tobias, Joseph D; Gossett, Jeffrey M; Morales, Laura; Gupta, Punkaj

    2012-10-01

    The primary objective of this study was to evaluate the hemodynamic effects of dexmedetomidine (DEX) infusion on critically ill neonates and infants with congenital heart disease (CHD). The secondary objective of the study was to evaluate the safety and efficacy profile of the drug in this patient population. A retrospective observational study was conducted in the cardiovascular intensive care unit (CVICU) of a single tertiary care university children's hospital. The charts of all neonates and infants who received DEX in the authors' pediatric CVICU between August 2009 and June 2010 were retrospectively reviewed. The demographic data collected included age, weight, sex, diagnosis, and Risk Adjustment in Congenital Heart Surgery (RACHS-1) score. To evaluate the hemodynamic effects of DEX, physiologic data were collected including heart rate, mean arterial pressure (MAP), inotrope score, near-infrared spectroscopy, and central venous pressure (CVP). To assess the efficacy of DEX, the amount and duration of concomitant sedation and analgesic infusions over a period of 24 h were examined together with the number of rescue boluses. The potential side effects evaluated in this study included nausea, vomiting, abdominal distension, dysrhythmias, neurologic abnormalities, seizures, and signs and symptoms of withdrawal. During the study period, 50 neonates and infants received DEX for a median period of 78 h (range, 40-290 h). These patients had an average age of 3.53 ± 2.64 months and a weight of 4.85 ± 1.67 kg. Whereas 34 patients (68%) received DEX after surgery for CHD, 15 patients (30%) received DEX after heart transplantation. Of these 50 infants, 10 (20%) had a single-ventricle anatomy, whereas 13 (26%) had a risk adjustment score (RACHS-1) in the category of 4-6. The median CVICU stay was 29 days (range, 8-69 days). Despite a significant decrease in heart rate, MAP, inotrope score, and CVP, all the patients remained hemodynamically stable during DEX infusion

  7. Early Detection of Drug-Induced Renal Hemodynamic Dysfunction Using Sonographic Technology in Rats

    PubMed Central

    Fisch, Sudeshna; Liao, Ronglih; Hsiao, Li-Li; Lu, Tzongshi

    2016-01-01

    The kidney normally functions to maintain hemodynamic homeostasis and is a major site of damage caused by drug toxicity. Drug-induced nephrotoxicity is estimated to contribute to 19- 25% of all clinical cases of acute kidney injury (AKI) in critically ill patients. AKI detection has historically relied on metrics such as serum creatinine (sCr) or blood urea nitrogen (BUN) which are demonstrably inadequate in full assessment of nephrotoxicity in the early phase of renal dysfunction. Currently, there is no robust diagnostic method to accurately detect hemodynamic alteration in the early phase of AKI while such alterations might actually precede the rise in serum biomarker levels. Such early detection can help clinicians make an accurate diagnosis and help in in decision making for therapeutic strategy. Rats were treated with Cisplatin to induce AKI. Nephrotoxicity was assessed for six days using high-frequency sonography, sCr measurement and upon histopathology of kidney. Hemodynamic evaluation using 2D and Color-Doppler images were used to serially study nephrotoxicity in rats, using the sonography. Our data showed successful drug-induced kidney injury in adult rats by histological examination. Color-Doppler based sonographic assessment of AKI indicated that resistive-index (RI) and pulsatile-index (PI) were increased in the treatment group; and peak-systolic velocity (mm/s), end-diastolic velocity (mm/s) and velocity-time integral (VTI, mm) were decreased in renal arteries in the same group. Importantly, these hemodynamic changes evaluated by sonography preceded the rise of sCr levels. Sonography-based indices such as RI or PI can thus be useful predictive markers of declining renal function in rodents. From our sonography-based observations in the kidneys of rats that underwent AKI, we showed that these noninvasive hemodynamic measurements may consider as an accurate, sensitive and robust method in detecting early stage kidney dysfunction. This study also

  8. Investigation of the Hemodynamic Effect of Stent Wires on Renal Arteries in Patients with Abdominal Aortic Aneurysms Treated with Suprarenal Stent-Grafts

    SciTech Connect

    Sun Zhonghua; Chaichana, Thanapong

    2009-07-15

    The purpose of the study was to investigate the hemodynamic effect of stent struts (wires) on renal arteries in patients with abdominal aortic aneurysms (AAAs) treated with suprarenal stent-grafts. Two sample patients with AAA undergoing multislice CT angiography pre- and postsuprarenal fixation of stent-grafts were selected for inclusion in the study. Eight juxtarenal models focusing on the renal arteries were generated from the multislice CT datasets. Four types of configurations of stent wires crossing the renal artery ostium were simulated in the segmented aorta models: a single wire crossing centrally, a single wire crossing peripherally, a V-shaped wire crossing centrally, and multiple wires crossing peripherally. The blood flow pattern, flow velocity, wall pressure, and wall shear stress at the renal arteries pre- and post-stent-grafting were analyzed and compared using a two-way fluid structure interaction analysis. The stent wire thickness was simulated with a diameter of 0.4, 1.0, and 2.0 mm, and hemodynamic analysis was performed at different cardiac cycles. The interference of stent wires with renal blood flow was mainly determined by the thickness of stent wires and the type of configuration of stent wires crossing the renal ostium. The flow velocity was reduced by 20-30% in most of the situations when the stent wire thickness increased to 1.0 and 2.0 mm. Of the four types of configuration, the single wire crossing centrally resulted in the highest reduction of flow velocity, ranging from 21% to 28.9% among three different wire thicknesses. Wall shear stress was also dependent on the wire thickness, which decreased significantly when the wire thickness reached 1.0 and 2.0 mm. In conclusion, our preliminary study showed that the hemodynamic effect of suprarenal stent wires in patients with AAA treated with suprarenal stent-grafts was determined by the thickness of suprarenal stent wires. Research findings in our study are useful for follow-up of

  9. Assessment of left ventricular hemodynamic forces in healthy subjects and patients with dilated cardiomyopathy using 4D flow MRI.

    PubMed

    Eriksson, Jonatan; Bolger, Ann F; Ebbers, Tino; Carlhäll, Carl-Johan

    2016-02-01

    We hypothesized that the direction of global left ventricular (LV) hemodynamic forces during diastolic filling are concordant with the main flow axes in normal LVs, but that this pattern would be altered in dilated and dysfunctional LVs. Therefore, we aimed to assess the LV hemodynamic filling forces in a group of healthy subjects and compare them to the results from a group of patients with dilated cardiomyopathy (DCM). Ten healthy subjects and 10 DCM patients were enrolled. Morphological short- (SAx) and long-axis (LAx) images and 4D flow MRI data were acquired at 1.5T. The LV pressure gradients were computed from the 4D flow data using the Navier-Stokes equations. By integrating the pressure gradients over the LV volume at each time frame, the magnitude and direction of the global hemodynamic force was calculated over the cardiac cycle. The hemodynamic forces acting in the SAx- and LAx-directions were used to calculate the "SAx-max/LAx-max"-ratio for the early (E-wave) and late (A-wave) diastolic filling. In the LAx-plane, the temporal progression of the hemodynamic force followed a consistent pattern in the healthy subjects. The "SAx-max/LAx-max"-ratio was significantly larger at both E-wave (0.53 ± 0.15 vs. 0.23 ± 0.12, P < 0.0001) and A-wave (0.44 ± 0.21 vs. 0.26 ± 0.09, P < 0.03) in the DCM patients compared to the healthy subjects. 4D flow MRI data allow quantification of LV hemodynamic forces acting on the LV myocardial wall. The LV hemodynamic filling forces showed a similar temporal progression among healthy subjects, whereas DCM patients had forces that were more heterogeneous in their direction and magnitude during diastole. PMID:26841965

  10. Assessment of left ventricular hemodynamic forces in healthy subjects and patients with dilated cardiomyopathy using 4D flow MRI.

    PubMed

    Eriksson, Jonatan; Bolger, Ann F; Ebbers, Tino; Carlhäll, Carl-Johan

    2016-02-01

    We hypothesized that the direction of global left ventricular (LV) hemodynamic forces during diastolic filling are concordant with the main flow axes in normal LVs, but that this pattern would be altered in dilated and dysfunctional LVs. Therefore, we aimed to assess the LV hemodynamic filling forces in a group of healthy subjects and compare them to the results from a group of patients with dilated cardiomyopathy (DCM). Ten healthy subjects and 10 DCM patients were enrolled. Morphological short- (SAx) and long-axis (LAx) images and 4D flow MRI data were acquired at 1.5T. The LV pressure gradients were computed from the 4D flow data using the Navier-Stokes equations. By integrating the pressure gradients over the LV volume at each time frame, the magnitude and direction of the global hemodynamic force was calculated over the cardiac cycle. The hemodynamic forces acting in the SAx- and LAx-directions were used to calculate the "SAx-max/LAx-max"-ratio for the early (E-wave) and late (A-wave) diastolic filling. In the LAx-plane, the temporal progression of the hemodynamic force followed a consistent pattern in the healthy subjects. The "SAx-max/LAx-max"-ratio was significantly larger at both E-wave (0.53 ± 0.15 vs. 0.23 ± 0.12, P < 0.0001) and A-wave (0.44 ± 0.21 vs. 0.26 ± 0.09, P < 0.03) in the DCM patients compared to the healthy subjects. 4D flow MRI data allow quantification of LV hemodynamic forces acting on the LV myocardial wall. The LV hemodynamic filling forces showed a similar temporal progression among healthy subjects, whereas DCM patients had forces that were more heterogeneous in their direction and magnitude during diastole.

  11. Managing resilience by creating purpose.

    PubMed

    Spake, Michael; Thompson, Elaine C

    2013-01-01

    Rapid, disruptive change is today's normal. It comes in all forms and frequencies. To cope and survive, healthcare executives need to build a culture of agility and resilience at all levels and across all domains of the hospital or health system. Lakeland Regional Health Systems Inc. has been transforming its culture in order to manage resilience by creating purpose. To adapt and sustain itself, Lakeland Regional has launched a transformation from a culture characterized by a collection of single values to one whose core is caring relationships through human interaction; human experience; and community values, beliefs, and attitudes. With a clear purpose of caring for ourselves, caring for our patients and families, caring for each other, and caring for our community, Lakeland Regional is creating resilience by building a purpose that sets the stage for a resilient culture defined by purpose; passion; and a healthy work, spiritual, and life balance.

  12. Cafeteria/Multi-Purpose Spaces.

    ERIC Educational Resources Information Center

    Larsen, Christopher W.

    2001-01-01

    Highlights school cafeteria design criteria that creates dining facilities that are both social areas as well as eating spaces. Also examined are key design considerations for multi-purpose areas. (GR)

  13. Hemodynamic Responses of Unfit Healthy Women at a Training Session with Nintendo Wii: A Possible Impact on the General Well-Being

    PubMed Central

    Monteiro-Junior, Renato S; Figueiredo, Luiz F; Conceição, Isabel; Carvalho, Carolina; Lattari, Eduardo; Mura, Gioia; Machado, Sérgio; da Silva, Elirez B

    2014-01-01

    Aims: The purpose of this study was assess the effect of a training session with Nintendo Wii® on the hemodynamic responses of healthy women not involved in regular physical exercise. Method: Twenty-five healthy unfit women aged 28 ± 6 years played for 10 minutes the game Free Run (Wii Fit Plus). The resting heart rate (RHR), systolic and diastolic blood pressures (SBP and DBP), and double (rate-pressure) product (DP) were measured before and after activity. The HR during the activity (exercise heart rate, EHR) was measured every minute. Results: A statistically significant difference was observed between the RHR (75 ± 9 bpm) and the mean EHR (176 ± 15 bpm) (P < 0.001). The EHR remained in the target zone for aerobic exercise until the fifth minute of activity, which coincided with the upper limit of the aerobic zone (80% heart rate reserve (HRR) + RHR) from the sixth to tenth minute. The initial (110 ± 8 mmHg) and final (145 ± 17 mmHg) SBP (P < 0.01) were significantly different, as were the initial (71 ± 8 mmHg) and final (79 ± 9 mmHg) DBP (P < 0.01). A statistically significant difference was observed between the pre- (8.233 ± 1.141 bpm-mmHg) and post-activity (25.590 ± 4.117 bpm-mmHg) DP (P < 0.01). Conclusion: Physical exercise while playing Free Run sufficed to trigger acute hemodynamic changes in healthy women who were not engaged in regular physical exercise. PMID:25614754

  14. A preliminary study on T-786C endothelial nitric oxide synthase gene and renal hemodynamic and blood pressure responses to dietary sodium.

    PubMed

    Dengel, D R; Brown, M D; Ferrell, R E; Reynolds, T H; Supiano, M A

    2007-01-01

    The purpose of the present study was to examine the role of the T-786C endothelial nitric oxide synthase (eNOS) gene polymorphism on changes in renal hemodynamics and blood pressure due to Na(+) loading. Twenty-eight older (63+/-1 years), moderately obese (39+/-2 % fat) hypertensives had their glomerular filtration rate (GFR), renal plasma flow (RPF), blood pressure (BP) and plasma nitric oxide (NO(x)) levels determined after eight days of low (20 mEq) and high (200 mEq) Na(+) diets. The two Na(+) diets were separated by a 1-week washout period. Subjects were genotyped for the eNOS-786 site and were grouped on whether they were homozygous or heterozygous for the C allele (TC+CC, n=13) or only homozygous for the T allele (TT, n=15). The TC+CC genotype group had a significantly greater increase in diastolic (P=0.021) and mean arterial (P=0.018) BP and a significant decline in both RPF (P=0.007) and GFR (P=0.029) compared to the TT genotype group with Na(+) loading. Furthermore, Na(+) loading resulted in a significant (P=0.036) increase in plasma NO(x) in the TT, but not in the TC+CC genotype group as well as a trend (P=0.051) for an increase in urine NO(x) in TC+CC, but not in the TT genotype group. The increase in BP during Na(+) loading in older hypertensives was associated with the eNOS genotype and may be related to changes in renal hemodynamics due to changes in NO metabolism.

  15. Effect of preoperative administration of intravenous paracetamol during cesarean surgery on hemodynamic variables relative to intubation, postoperative pain and neonatal apgar.

    PubMed

    Ayatollahi, Vida; Faghihi, Safa; Behdad, Shokoufeh; Heiranizadeh, Najmeh; Baghianimoghadam, Behnam

    2014-09-01

    Selection of anesthetic drugs for cesarean section requires many considerations. Anesthetic drugs for this purpose must prevent hemodynamic stress due to tracheal intubation, while inducing neonatal complications. This study was conducted to determine the effects of paracetamol given before induction of anesthesia on cardiovascular responses to tracheal intubation and postoperative pain in the mother, and on neonatal Apgar score. This double-blind randomized placebo-controlled trial included 60 women in ASA I, without underlying diseases and fetal distress, who were candidates for elective cesarean section under general anesthesia. Patients were divided into two groups of 30 patients. Patients in the paracetamol group received 1 g intravenous (IV) paracetamol 20 min before the operation, while those in the placebo group received 1 cc normal saline at the same time. In both groups, anesthesia was induced by sodium thiopental and succinylcholine. Maternal systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and heart rate (HR) were measured before and immediately upon induction of anesthesia, and at first and fifth minute after tracheal intubation. Neonatal effects were assessed by Apgar score. Postoperative pain was assessed by use of the visual analog scale (VAS). The dose of analgesic used and the time of the first analgesic request by patients postoperatively were recorded. The SBP, DBP, MAP and HR were controlled significantly better in paracetamol group than in placebo group (P < 0.05). The mean 1-min and 5-min Apgar scores of neonates did not differ between the groups. The VAS pain score was significantly lower in paracetamol group than in placebo group at all measuring times (P < 0.05). Also, paracetamol caused later first analgesic request and lower dose of analgesic needed to control pain postoperatively (P < 0.05). In conclusion, the results of our study suggested IV paracetamol to be an efficacious agent to decrease

  16. Impaired regional hemodynamic response in schizophrenia during multiple prefrontal activation tasks: a two-channel near-infrared spectroscopy study.

    PubMed

    Ikezawa, Koji; Iwase, Masao; Ishii, Ryouhei; Azechi, Michiyo; Canuet, Leonides; Ohi, Kazutaka; Yasuda, Yuka; Iike, Naomi; Kurimoto, Ryu; Takahashi, Hidetoshi; Nakahachi, Takayuki; Sekiyama, Ryuji; Yoshida, Tetsuhiko; Kazui, Hiroaki; Hashimoto, Ryota; Takeda, Masatoshi

    2009-03-01

    In schizophrenia, dysfunction of the prefrontal cortex (PFC), regarded as a core feature of the disease, has been investigated by different neuroimaging methods. Near infrared spectroscopy (NIRS), a novel neurophysiological method, is being increasingly used in the investigation of frontal dysfunction in schizophrenia. However, NIRS measurements during multiple frontal activation tasks have been rarely reported. The purpose of this study was to compare hemodynamic changes in the PFC between patients with schizophrenia and healthy controls during four different types of frontal lobe tasks using a 2-channel NIRS system. Thirty patients with schizophrenia and thirty age- and gender-matched healthy controls were enrolled in this study. In both groups, changes in oxygenated hemoglobin concentration (Delta[oxyHb]) at the bilateral forehead were measured during Verbal fluency test letter version (VFT-letter), VFT category version, Tower of Hanoi (TOH), the Sternberg and Stroop tasks. Regarding Delta[oxyHb] in PFC, a diagnosis group effect was found for VFT-letter and TOH. Significant negative correlation was found between left Delta[oxyHb] during TOH and negative and cognitive symptom scores in schizophrenia patients. Right Delta[oxyHb] during TOH also showed significant negative correlation with cognitive symptoms scores. No significant correlation between Delta[oxyHb] and clinical characteristics were observed during VFT-letter. These findings suggest that among a battery of frontal lobe tasks administered to schizophrenia patients, VFT-letter and TOH are more sensitive to detect PFC activation, as indicated by Delta[oxyHb] using a 2-channel NIRS. Taken together, these findings and those of previous neuroimaging studies suggest that VFT-letter and TOH might represent possible candidate physiological markers of prefrontal dysfunction in schizophrenia, though extensive testing in clinical settings will be necessary. PMID:19157786

  17. In vivo pO2 imaging of tumors: Oxymetry with very low frequency Electron Paramagnetic Resonance

    PubMed Central

    Epel, Boris; Halpern, Howard J.

    2016-01-01

    For over a century it has been known that tumor hypoxia, regions of a tumor with low levels of oxygenation, are important contributors to tumor resistance to radiation therapy and failure of radiation treatment of cancer. Recently, using novel pulse electron paramagnetic resonance (EPR) oxygen imaging, near absolute images of the partial pressure of oxygen (pO2) in tumors of living animals have been obtained. We discuss here the means by which EPR signals can be obtained in living tissues and tumors. We review development of EPR methods to image the pO2 in tumors and the potential for the pO2 image acquisition in human subjects. PMID:26477263

  18. Early non-invasive cardiac output monitoring in hemodynamically unstable intensive care patients: A multi-center randomized controlled trial

    PubMed Central

    2011-01-01

    Introduction Acute hemodynamic instability increases morbidity and mortality. We investigated whether early non-invasive cardiac output monitoring enhances hemodynamic stabilization and improves outcome. Methods A multicenter, randomized controlled trial was conducted in three European university hospital intensive care units in 2006 and 2007. A total of 388 hemodynamically unstable patients identified during their first six hours in the intensive care unit (ICU) were randomized to receive either non-invasive cardiac output monitoring for 24 hrs (minimally invasive cardiac output/MICO group; n = 201) or usual care (control group; n = 187). The main outcome measure was the proportion of patients achieving hemodynamic stability within six hours of starting the study. Results The number of hemodynamic instability criteria at baseline (MICO group mean 2.0 (SD 1.0), control group 1.8 (1.0); P = .06) and severity of illness (SAPS II score; MICO group 48 (18), control group 48 (15); P = .86)) were similar. At 6 hrs, 45 patients (22%) in the MICO group and 52 patients (28%) in the control group were hemodynamically stable (mean difference 5%; 95% confidence interval of the difference -3 to 14%; P = .24). Hemodynamic support with fluids and vasoactive drugs, and pulmonary artery catheter use (MICO group: 19%, control group: 26%; P = .11) were similar in the two groups. The median length of ICU stay was 2.0 (interquartile range 1.2 to 4.6) days in the MICO group and 2.5 (1.1 to 5.0) days in the control group (P = .38). The hospital mortality was 26% in the MICO group and 21% in the control group (P = .34). Conclusions Minimally-invasive cardiac output monitoring added to usual care does not facilitate early hemodynamic stabilization in the ICU, nor does it alter the hemodynamic support or outcome. Our results emphasize the need to evaluate technologies used to measure stroke volume and cardiac output--especially their impact on the process of care--before any large

  19. Hemodynamic Consequences of Malignant Ascites in Epithelial Ovarian Cancer Surgery*: A Prospective Substudy of a Randomized Controlled Trial.

    PubMed

    Hunsicker, Oliver; Fotopoulou, Christina; Pietzner, Klaus; Koch, Mandy; Krannich, Alexander; Sehouli, Jalid; Spies, Claudia; Feldheiser, Aarne

    2015-12-01

    Malignant ascites (MA) is most commonly observed in patients scheduled for epithelial ovarian cancer (EOC) surgery and is supposed as a major risk factor promoting perioperative hemodynamic deterioration. We aimed to assess the hemodynamic consequences of MA on systemic circulation in patients undergoing cytoreductive EOC surgery.This study is a predefined post-hoc analysis of a randomized controlled pilot trial comparing intravenous solutions within a goal-directed algorithm to optimize hemodynamic therapy in patients undergoing cytoreductive EOC surgery. Ascites was used to stratify the EOC patients prior to randomization in the main study. We analyzed 2 groups according to the amount of ascites (NLAS: none or low ascites [<500 mL] vs HAS: high ascites group [>500 mL]). Differences in hemodynamic variables with respect to time were analyzed using nonparametric analysis for longitudinal data and multivariate generalized estimating equation adjusting the analysis for the randomized study groups of the main study.A total of 31 patients in the NLAS and 16 patients in the HAS group were analyzed. Although cardiac output was not different between groups suggesting a similar circulatory blood flow, the HAS group revealed higher heart rates and lower stroke volumes during surgery. There were no differences in pressure-based hemodynamic variables. In the HAS group, fluid demands, reflected by the time to reindication of a fluid challenge after preload optimization, increased steadily, whereas stroke volume could not be maintained at baseline resulting in hemodynamic instability after 1.5 h of surgery. In contrast, in the NLAS group fluid demands were stable and stroke volume could be maintained during surgery. Clinically relevant associations of the type of fluid replacement with hemodynamic consequences were particularly observed in the HAS group, in which transfusion of fresh frozen plasma (FFP) was associated to an improved circulatory flow and reduced

  20. Hemodynamic Response Alteration As a Function of Task Complexity and Expertise—An fNIRS Study in Jugglers

    PubMed Central

    Carius, Daniel; Andrä, Christian; Clauß, Martina; Ragert, Patrick; Bunk, Michael; Mehnert, Jan

    2016-01-01

    Detailed knowledge about online brain processing during the execution of complex motor tasks with a high motion range still remains elusive. The aim of the present study was to investigate the hemodynamic responses within sensorimotor networks as well as in visual motion area during the execution of a complex visuomotor task such as juggling. More specifically, we were interested in how far the hemodynamic response as measured with functional near infrared spectroscopy (fNIRS) adapts as a function of task complexity and the level of the juggling expertise. We asked expert jugglers to perform different juggling tasks with different levels of complexity such as a 2-ball juggling, 3- and 5-ball juggling cascades. We here demonstrate that expert jugglers show an altered neurovascular response with increasing task complexity, since a 5-ball juggling cascade showed enhanced hemodynamic responses for oxygenated hemoglobin as compared to less complex tasks such as a 3- or 2-ball juggling pattern. Moreover, correlations between the hemodynamic response and the level of the juggling expertise during the 5-ball juggling cascade, acquired by cinematographic video analysis, revealed only a non-significant trend in primary motor cortex, indicating that a higher level of expertise might be associated with lower hemodynamic responses. PMID:27064925

  1. Right ventricular infarction: identification by hemodynamic measurements before and after volume loading and correlation with noninvasive techniques

    SciTech Connect

    Dell'Italia, L.J.; Starling, M.R.; Crawford, M.H.; Boros, B.L.; Chaudhuri, T.K.; O'Rourke, R.A.

    1984-11-01

    To evaluate the potential occurrence of right ventricular infarction, 53 patients with acute inferior transmural myocardial infarction were studied within 36 hours of symptoms by right heart catheterization, equilibrium radionuclide angiography and two-dimensional echocardiography. Technetium-99m pyrophosphate myocardial scintigraphy was performed 3 days after the onset of symptoms. The hemodynamic standard for right ventricular infarction was defined as both a right atrial pressure of 10 mm Hg or more and a right atrial/pulmonary artery wedge pressure ratio of 0.8 or more. Eight (15%) of the 53 patients had hemodynamic measurements at rest characteristic of right ventricular infarction, and 6 (11%) additional patients met these criteria after volume loading. Nineteen (37%) of the 51 patients who had radionuclide angiography had right ventricular dysfunction manifested by both a reduced right ventricular ejection fraction (less than 40%) and right ventricular regional wall motion abnormalities (akinesia or dyskinesia). An abnormal radionuclide angiogram was observed in 12 of 13 patients with hemodynamic measurements indicating right ventricular infarction. In 12 patients with an abnormal radionuclide angiographic study, right ventricular ejection fraction improved 6 to 12 weeks after infarction. Twenty-two (49%) of the 45 patients with adequate two-dimensional echocardiograms had a right ventricular regional wall motion abnormality. An abnormal two-dimensional echocardiogram was seen in 9 of 11 patients with hemodynamic measurements characteristic of right ventricular infarction. Technetium-99m pyrophosphate scintigraphy was positive for right ventricular infarction in 3 of 12 patients who had hemodynamic measurements indicating right ventricular infarction.

  2. Relationship between prefrontal hemodynamic responses and quality of life differs between melancholia and non-melancholic depression.

    PubMed

    Tsujii, Noa; Mikawa, Wakako; Tsujimoto, Emi; Akashi, Hiroyuki; Adachi, Toru; Kirime, Eiji; Shirakawa, Osamu

    2016-07-30

    This study aimed to determine whether quality of life (QOL) reflects specific functional abnormalities of frontotemporal hemodynamic responses in melancholia. We recruited 30 patients with major depressive disorder (MDD) with melancholic features (MDD-MF), 52 with non-melancholic features (MDD-NMF), and 68 healthy control subjects who were matched for age, sex ratio, and years of education. QOL was assessed using the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36), and regional hemodynamic responses during a verbal fluency task were monitored with near-infrared spectroscopy (NIRS). Patients with MDD-MF scored significantly lower than those with MDD-NMF on the role emotional domain of SF-36. Both MDD patient groups exhibited lower hemodynamic responses in the frontotemporal regions than the control group. Hemodynamic responses in the frontotemporal regions were significantly smaller in patients with MDD-MF than in those with MDD-NMF. The role emotional domain of patients with MDD-MF was significantly and positively correlated with hemodynamic responses in the prefrontal region, whereas that of patients with MDD-NMF revealed no significant correlation. In conclusion, our results indicate that patients with MDD-MF exhibit qualitatively distinct prefrontal dysfunction patterns associated with emotional role functioning compared with patients with MDD-NMF. PMID:27259838

  3. ACUTE IMPROVEMENT IN HEMODYNAMIC CONTROL AFTER OSTEOPATHIC MANIPULATIVE TREATMENT IN THE THIRD TRIMESTER OF PREGNANCY

    PubMed Central

    Hensel, Kendi L.; Pacchia, Christina F.; Smith, Michael L.

    2013-01-01

    Objectives The physiological changes that occur during pregnancy, including increased blood volume and cardiac output, can affect hemodynamic control, most profoundly with positional changes that affect venous return to the heart. By using Osteopathic Manipulative Treatment (OMT), a body-based modality theorized to affect somatic structures related to nervous and circulatory systems, we hypothesized that OMT acutely improves both autonomic and hemodynamic control during head-up tilt and heel raise in women at 30 weeks gestation. Design One hundred subjects were recruited at 30 weeks gestation. Setting The obstetric clinics of UNTHealth in Fort Worth, Texas. Intervention Subjects were randomized into one of three treatment groups: OMT, placebo ultrasound, or time control. Ninety subjects had complete data (N=25, 31 and 34 in each group respectively). Main outcome measures Blood pressure and heart rate were recorded during 5 min of head-up tilt followed by 4 min of intermittent heel raising. Results No significant differences in blood pressure, heart rate or heart rate variability were observed between groups with tilt before or after treatment (p>0.36), and heart rate variability was not different between treatment groups (p>0.55). However, blood pressure increased significantly (p=0.02) and heart rate decreased (p<0.01) during heel raise after OMT compared to placebo or time control. Conclusions These data suggest that OMT can acutely improve hemodynamic control during engagement of the skeletal muscle pump and this was most likely due to improvement of structural restrictions to venous return. PMID:24280470

  4. Obesity and the Role of Short Duration Submaximal Work on Cardiovascular and Cerebral Hemodynamics

    PubMed Central

    Cavuoto, Lora A.; Maikala, Rammohan V.

    2016-01-01

    The objective of this study was to compare gas exchange, cardiac and cerebral hemodynamic responses between 10 non-obese and 10 obese men during submaximal work. With the increasing prevalence of obesity, there is a need to understand the impact of obesity on work-induced responses. Participants completed a step-wise incremental cycling until they reached 60% of their age-predicted maximum heart rate. Gas exchange, cardiac and pre-frontal cortex hemodynamic responses were simultaneously measured during rest, work, and recovery. The non-obese group reached ~43% of their predicted maximal aerobic capacity as compared to ~34% in the obese group, with the non-obese working at a relatively higher workload and for more duration than the obese. The obese had elevated baseline heart rate and reduced whole-body oxygen uptake per body weight at baseline and task termination. Other cardiac and cerebral responses, although increased from baseline, were similar between groups during submaximal effort. In the obese, during recovery oxygen uptake and heart-rate recovery were slowest; cardiac output and rate pressure product were greatest, and left ventricle ejection time was shortest. However, both groups exhibited similar cerebral hemodynamics during recovery. These finding imply that, irrespective of their low aerobic fitness, obesity does not impair myocardial performance and cerebrovascular function during graded submaximal work, however, recovery from a short duration of work was influenced by their fitness level. Since a majority of activities of daily living are performed at individual’s submaximal level, understanding influence of obesity on submaximal work is critical. PMID:27088872

  5. Hemodynamic Differences Between Central ECMO and Peripheral ECMO: A Primary CFD Study.

    PubMed

    Gu, Kaiyun; Zhang, Ya; Gao, Bin; Chang, Yu; Zeng, Yi

    2016-03-03

    BACKGROUND Veno-arterial extracorporeal membrane oxygenation (VAECMO), including central ECMO (cECMO) and peripheral ECMO (pECMO), is widely used in cardiopulmonary surgery. The outcomes and complications of both types of ECMO are quite different from each other. The hemodynamic differences among them are hypothesized as a key factor. Hence, a numerical study was conducted to test this hypothesis. MATERIAL AND METHODS Ideal cardiovascular models with pECMO and cECMO were established. The aortic pressure and flow rate were chosen as boundary conditions. The flow pattern, blood flow distributions, flow junction, harmonic index (HI) of blood flow, wall shear stress (WSS), and the oscillatory shear index (OSI) were calculated to evaluate the hemodynamic states. RESULTS pECMO could achieve better upper limb and brain perfusion (0.05458 vs. 0.05062 kg/s), and worse lower limb perfusion (0.03067 vs. 0.03401 kg/s). There exist low WSS (<0.4 pa) regions at the inner and posterior wall of the aorta, and high WSS (>2 pa) region at the access of the femoral artery. These regions also have relatively high OSI value (reaching 0.45). In contrast, for cECMO, there exist high WSS at the posterior wall of the aortic arch. CONCLUSIONS The hemodynamic performances of various types of ECMO are different from each other, which maybe the key reasons for the differences in the outcomes and complications. Therefore, for pEMCO, the lower-extremity ischemia is a complication that must be considered. The type, support level, and duration of ECMO should also be carefully regulated according to the patients' condition, as they are the important factors related to vascular complications.

  6. Beta2-adrenoceptor genotype and function affect hemodynamic profile heterogeneity in postural tachycardia syndrome.

    PubMed

    Jacob, Giris; Garland, Emily M; Costa, Fernando; Stein, C Michael; Xie, Hong-Guang; Robertson, Rose Marie; Biaggioni, Italo; Robertson, David

    2006-03-01

    Previous studies suggest that the beta2-adrenoceptor functions abnormally in patients with postural tachycardia syndrome (POTS) and may contribute to their altered hemodynamic profile. To test the hypothesis that the beta2-adrenoceptor response is decreased in POTS, we studied: (1) the arterial vasodilation response to the beta agonist, isoproterenol, and (2) the distribution of common polymorphisms (codons 16 and 27) of the gene coding the receptor (beta2-AR) in a large population with POTS. We measured plasma catecholamines and monitored hemodynamics and changes in forearm and leg blood flow to incremental doses of intraarterial isoproterenol in 9 patients with POTS compared with 8 healthy subjects. For polymorphism assessment we collected DNA from 57 patients with POTS and compared with 67 age-sex matched healthy subjects. Circulating catecholamines were significantly higher in POTS subjects compared with controls. Intrabrachial and intrafemoral isoproterenol infusion elicited a dose-dependent increase in blood flow. In healthy subjects, blood flow increased (mean+/-SEM) 400+/-70% in the forearm and 170+/-40% in the leg, but only 280+/-60% in forearms and 120+/-20% in legs of patients with POTS (ANOVA for both P<0.001). The genotype and allele distributions for codons 16 and 27 beta2-AR variants were not different in the 2 groups. However, the blood pressure and plasma norepinephrine levels diverged in patients according to their genotype. Patients with Gly16Gly and patients with Glu27Glu had lower plasma catecholamines and higher supine and upright blood pressure, compared with other genotypes. Therefore, both decreased beta2-adrenoceptor-related vasodilation and beta2-AR polymorphisms may contribute to the hemodynamic diversity of patients with POTS.

  7. Development and evaluation of a pliable biological valved conduit. Part II: Functional and hemodynamic evaluation.

    PubMed

    Sung, H W; Witzel, T H; Hata, C; Tu, R; Shen, S H; Lin, D; Noishiki, Y; Tomizawa, Y; Quijano, R C

    1993-04-01

    Many congenital cardiac malformations may require a valved conduit for the reconstruction of the right ventricular outflow tract. In spite of many endeavors made in the last 25 years, the clinical results of right ventricular outflow tract reconstruction with currently available valved conduits are still not satisfactory. Specific problems encountered clinically include suboptimal hemodynamic performance, conduit kinking or compression, and fibrous peeling from the luminal surface. To address these deficiencies, we undertook the development of a biological valved conduit: a bovine external jugular vein graft with a retained native valve cross-linked with a diglycidyl ether (DE). This study, using a canine model, was to evaluate the functional and hemodynamic performance of this newly developed valved conduit. Three 14 mm conduits, implanted as bypass grafts, right ventricle to pulmonary artery, were evaluated. The evaluation was conducted with a noninvasive color Doppler flow mapping system at pre-implantation, immediately post implantation, one- and three-months post implantation, and prior to retrieval (five-months post implantation). The two-dimensional tomographic inspection of the leaflet motion at various periods post implantation showed that the valvular leaflets in the DE treated conduit was quite pliable. No cardiac failure or valvular dysfunction was observed in any of the studied cases. The color Doppler flow mapping study demonstrated that the valve in the DE treated conduit was competent, with no conduit kinking or compression observed in any of the three cases. The spectral Doppler velocity study evidenced that the transvalvular pressure gradients of the DE treated conduit were minimal as compared to those of the currently available conduits. In conclusion, from the functional and hemodynamic performance points of view, this newly developed valved conduit is superior to those currently available. PMID:8325697

  8. Estradiol improves pulmonary hemodynamics and vascular remodeling in perinatal pulmonary hypertension.

    PubMed

    Parker, T A; Ivy, D D; Galan, H L; Grover, T R; Kinsella, J P; Abman, S H

    2000-02-01

    Partial ligation of the ductus arteriosus (DA) in the fetal lamb causes sustained elevation of pulmonary vascular resistance (PVR) and hypertensive structural changes in small pulmonary arteries, providing an animal model for persistent pulmonary hypertension of the newborn. Based on its vasodilator and antimitogenic properties in other experimental studies, we hypothesized that estradiol (E(2)) would attenuate the pulmonary vascular structural and hemodynamic changes caused by pulmonary hypertension in utero. To test our hypothesis, we treated chronically instrumented fetal lambs (128 days, term = 147 days) with daily infusions of E(2) (10 microg; E(2) group, n = 6) or saline (control group, n = 5) after partial ligation of the DA. We measured intrauterine pulmonary and systemic artery pressures in both groups throughout the study period. After 8 days, we delivered the study animals by cesarean section to measure their hemodynamic responses to birth-related stimuli. Although pulmonary and systemic arterial pressures were not different in utero, fetal PVR immediately before ventilation was reduced in the E(2)-treated group (2.43 +/- 0.79 vs. 1.48 +/- 0.26 mmHg. ml(-1). min, control vs. E(2), P < 0.05). During the subsequent delivery study, PVR was lower in the E(2)-treated group in response to ventilation with hypoxic gas but was not different between groups with ventilation with 100% O(2). During mechanical ventilation after delivery, arterial partial O(2) pressure was higher in E(2) animals than controls (41 +/- 11 vs. 80 +/- 35 Torr, control vs. E(2), P < 0. 05). Morphometric studies of hypertensive vascular changes revealed that E(2) treatment decreased wall thickness of small pulmonary arteries (59 +/- 1 vs. 48 +/- 1%, control vs. E(2), P < 0.01). We conclude that chronic E(2) treatment in utero attenuates the pulmonary hemodynamic and histological changes caused by DA ligation in fetal lambs. PMID:10666122

  9. Evaluating MRI based vascular wall motion as a biomarker of Fontan hemodynamic performance

    NASA Astrophysics Data System (ADS)

    Menon, Prahlad G.; Hong, Haifa

    2015-03-01

    The Fontan procedure for single-ventricle heart disease involves creation of pathways to divert venous blood from the superior & inferior venacavae (SVC, IVC) directly into the pulmonary arteries (PA), bypassing the right ventricle. For optimal surgical outcomes, venous flow energy loss in the resulting vascular construction must be minimized and ensuring close to equal flow distribution from the Fontan conduit connecting IVC to the left & right PA is paramount. This requires patient-specific hemodynamic evaluation using computational fluid dynamics (CFD) simulations which are often time and resource intensive, limiting applicability for real-time patient management in the clinic. In this study, we report preliminary efforts at identifying a new non-invasive imaging based surrogate for CFD simulated hemodynamics. We establish correlations between computed hemodynamic criteria from CFD modeling and cumulative wall displacement characteristics of the Fontan conduit quantified from cine cardiovascular MRI segmentations over time (i.e. 20 cardiac phases gated from the start of ventricular systole), in 5 unique Fontan surgical connections. To focus our attention on diameter variations while discounting side-to-side swaying motion of the Fontan conduit, the difference between its instantaneous regional expansion and inward contraction (averaged across the conduit) was computed and analyzed. Maximum Fontan conduit-average expansion over the cardiac cycle correlated with the anatomy-specific diametric offset between the axis of the IVC and SVC (r2=0.13, p=0.55) - a known factor correlated with Fontan energy loss and IVC-to-PA flow distribution. Investigation in a larger study cohort is needed to establish stronger statistical correlations.

  10. Acute hemodynamic effects and blood pool kinetics of polystyrene microspheres following intravenous administration

    SciTech Connect

    Slack, J.D.; Kanke, M.; Simmons, G.H.; DeLuca, P.P.

    1981-06-01

    The acute hemodynamic effect of intravenous administration of polystyrene microspheres was investigated and correlated with their distribution pattern and kinetics. Microspheres of three diameters (3.4, 7.4, and 11.6 micrometer) were administered. The 7.4- and 11.6-micrometer diameter microspheres were filtered by the pulmonary capillary network following intravenous administration, the majority during the first pass. There was no significant hemodynamic effect following administrations of the 7.4- and 11.6-micrometer diameter microspheres in doses as high as 3.0 X 10(9) and 6.1 X 10(8) respectively (total cross-sectional area of 1.3 X 10(11) and 6.4 X 10(10) micrometer2, respectively). Intravenous administration of 3.4-micrometer diameter microspheres produced significant dose-dependent systemic hypotension and depression of myocardial performance at dosages as slow as 1.0 X 10(10) (cross-sectional area of 9.1 X 10(10) micrometer2). These differences in acute hemodynamic effect from the 7.4- and 11.6-micrometer diameter microspheres may be due to the differences in distribution kinetics and fate of the 3.4-micrometer diameter microspheres, which readily pass through the lungs to the spleen. Although elimination of the smaller spheres from the blood during the first 6-8 min was rapid, i.e., t 1/2 . 1.62 and 1.72 min from the venous and arterial blood circulation, respectively, levels of 10(3) spheres/g of blood were present in the circulation for greater than 1 hr. These findings must be considered in the planning of intravenous administration of microspheres as a drug delivery system to target organs.

  11. Novel Paradigms for Dialysis Vascular Access: Upstream Hemodynamics and Vascular Remodeling in Dialysis Access Stenosis

    PubMed Central

    Ene-Iordache, Bogdan

    2013-01-01

    Summary Failure of hemodialysis access is caused mostly by venous intimal hyperplasia, a fibro-muscular thickening of the vessel wall. The pathogenesis of venous neointimal hyperplasia in primary arteriovenous fistulae consists of processes that have been identified as upstream and downstream events. Upstream events are the initial events producing injury of the endothelial layer (surgical trauma, hemodynamic shear stress, vessel wall injury due to needle punctures, etc.). Downstream events are the responses of the vascular wall at the endothelial injury that consist of a cascade of processes including leukocyte adhesion, migration of smooth muscle cells from the media to the intimal layer, and proliferation. In arteriovenous fistulae, the stenoses occur in specific sites, consistently related to the local hemodynamics determined by the vessel geometry and blood flow pattern. Recent findings that the localization of these sites matches areas of disturbed flow may add new insights into the pathogenesis of neointimal hyperplasia in the venous side of vascular access after the creation of the anastomosis. The detailed study of fluid flow motion acting on the vascular wall in anastomosed vessels and in the arm vasculature at the patient-specific level may help to elucidate the role of hemodynamics in vascular remodeling and neointimal hyperplasia formation. These computational approaches may also help in surgical planning for the amelioration of clinical outcome. This review aims to discuss the role of the disturbed flow condition in acting as upstream event in the pathogenesis of venous intimal hyperplasia and in producing subsequent local vascular remodeling in autogenous arteriovenous fistulae used for hemodialysis access. The potential use of blood flow analysis in the management of vascular access is also discussed. PMID:23990161

  12. Effect of ocular shape and vascular geometry on retinal hemodynamics: a computational model.

    PubMed

    Dziubek, Andrea; Guidoboni, Giovanna; Harris, Alon; Hirani, Anil N; Rusjan, Edmond; Thistleton, William

    2016-08-01

    A computational model for retinal hemodynamics accounting for ocular curvature is presented. The model combines (i) a hierarchical Darcy model for the flow through small arterioles, capillaries and small venules in the retinal tissue, where blood vessels of different size are comprised in different hierarchical levels of a porous medium; and (ii) a one-dimensional network model for the blood flow through retinal arterioles and venules of larger size. The non-planar ocular shape is included by (i) defining the hierarchical Darcy flow model on a two-dimensional curved surface embedded in the three-dimensional space; and (ii) mapping the simplified one-dimensional network model onto the curved surface. The model is solved numerically using a finite element method in which spatial domain and hierarchical levels are discretized separately. For the finite element method, we use an exterior calculus-based implementation which permits an easier treatment of non-planar domains. Numerical solutions are verified against suitably constructed analytical solutions. Numerical experiments are performed to investigate how retinal hemodynamics is influenced by the ocular shape (sphere, oblate spheroid, prolate spheroid and barrel are compared) and vascular architecture (four vascular arcs and a branching vascular tree are compared). The model predictions show that changes in ocular shape induce non-uniform alterations of blood pressure and velocity in the retina. In particular, we found that (i) the temporal region is affected the least by changes in ocular shape, and (ii) the barrel shape departs the most from the hemispherical reference geometry in terms of associated pressure and velocity distributions in the retinal microvasculature. These results support the clinical hypothesis that alterations in ocular shape, such as those occurring in myopic eyes, might be associated with pathological alterations in retinal hemodynamics. PMID:26445874

  13. Non-invasive assessment of cerebral microcirculation with diffuse optics and coherent hemodynamics spectroscopy

    NASA Astrophysics Data System (ADS)

    Fantini, Sergio; Sassaroli, Angelo; Kainerstorfer, Jana M.; Tgavalekos, Kristen T.; Zang, Xuan

    2016-03-01

    We describe the general principles and initial results of coherent hemodynamics spectroscopy (CHS), which is a new technique for the quantitative assessment of cerebral hemodynamics on the basis of dynamic near-infrared spectroscopy (NIRS) measurements. The two components of CHS are (1) dynamic measurements of coherent cerebral hemodynamics in the form of oscillations at multiple frequencies (frequency domain) or temporal transients (time domain), and (2) their quantitative analysis with a dynamic mathematical model that relates the concentration and oxygen saturation of hemoglobin in tissue to cerebral blood volume (CBV), cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2). In particular, CHS can provide absolute measurements and dynamic monitoring of CBF, and quantitative measures of cerebral autoregulation. We report initial results of CBF measurements in hemodialysis patients, where we found a lower CBF (54 +/- 16 ml/(100 g-min)) compared to a group of healthy controls (95 +/- 11 ml/(100 g-min)). We also report CHS measurements of cerebral autoregulation, where a quantitative index of autoregulation (its cutoff frequency) was found to be significantly greater in healthy subjects during hyperventilation (0.034 +/- 0.005 Hz) than during normal breathing (0.017 +/- 0.002 Hz). We also present our approach to depth resolved CHS, based on multi-distance, frequency-domain NIRS data and a two-layer diffusion model, to enhance sensitivity to cerebral tissue. CHS offers a potentially powerful approach to the quantitative assessment and continuous monitoring of local brain perfusion at the microcirculation level, with prospective brain mapping capabilities of research and clinical significance.

  14. Hemodynamics during Rotary Blood Pump support with speed synchronization in heart failure condition: A modelling study.

    PubMed

    Htet, Zwe Lin; Aye, Thin Pa Pa; Singhavilai, Thamvarit; Naiyanetr, Phornphop

    2015-01-01

    The aim of this work is to study the hemodynamic changes in the cardiovascular system under different modes of Rotary Blood Pump (RBP) support. Continuous mode (constant pump speed) and co-pulse mode (increased pump speed in systole) are studied. Computer simulation studies have been conducted to evaluate the performances of these two modes under normal and pathological conditions. The pathological heart condition is simulated by reducing the maximum systolic elestance (Emax) in the cardiovascular system model. The model is implemented by using MATLAB Simulink. The pressure-volume loop of different heart conditions (normal heart: 100% of normal contractility, pathological heart: 30% of normal contractility) and the different modes of RBP support (8 krpm and 11 krpm in continuous mode, between 8 krpm and 11 krpm in co-pulse mode) are simulated. The results of this study show the slope of end systolic pressure volume relationship (ESPVR) changes in pathological condition. The reduction of area inside pressure volume loops depend on the increasing level of pump speed. The results indicated systolic aortic pressures in co-pulse mode are higher than in the continuous mode. In normal condition, the value of systolic aortic pressure in co-pulse mode is 113 mmHg and the values of systolic aortic pressures in continuous modes are 109 mmHg (8 k) and 95 mmHg (11 k). In pathological condition, the value of systolic aortic pressure in co pulse mode is 100 mmHg and the values of systolic aortic pressures in continuous modes are 90 mmHg (8 k) and 95 mmHg (11 k). The hemodynamics results of this study are comparable in vivo data, clinical data and other simulation studies. Therefore, this simulation enables hemodynamic studies in patients with end-stage heart failure, and patients under different modes of rotary blood pump support. PMID:26736999

  15. Improved Prediction of Disturbed Flow via Hemodynamically-Inspired Geometric Variables

    PubMed Central

    Bijari, Payam B.; Antiga, Luca; Gallo, Diego; Wasserman, Bruce A.; Steinman, David A.

    2012-01-01

    Arterial geometry has long been considered a pragmatic alternative for inferring arterial flow disturbances and their impact on the natural history and treatment of vascular diseases. Traditionally, definition of geometric variables is based on convenient shape descriptors, with only superficial consideration of their influence on flow and wall shear stress patterns. In the present study we demonstrate that a more studied consideration of the actual (c.f., nominal) local hemodynamics can lead to substantial improvements in the prediction of disturbed flow by geometry. Starting from a well-characterized computational fluid dynamics (CFD) dataset of 50 normal carotid bifurcations, we observed that disturbed flow tended to be confined proximal to the flow divider, whereas geometric variables previously shown to be significant predictors of disturbed flow included features distal to the flow divider in their definitions. Flaring of the bifurcation leading to flow separation was redefined as the maximum relative expansion of the common carotid artery (CCA), proximal to the flow divider. The beneficial effect of primary curvature on flow inertia, via suppression of flow separation, was characterized by the in-plane tortuosity of CCA as it enters the flare region. Multiple linear regressions of these redefined geometric variables against various metrics of disturbed flow revealed R2 values approaching 0.6, better than the roughly 0.3 achieved using the conventional shape-based variables, while maintaining their demonstrated real-world reproducibility. Such a hemodynamically-inspired approach to the definition of geometric variables may reap benefits for other applications where geometry is used as a surrogate marker of local hemodynamics. PMID:22552156

  16. Blood Pressure and Hemodynamic Adaptations after a Training Program in Young Individuals with Down Syndrome

    PubMed Central

    Seron, Bruna Barboza; Goessler, Karla Fabiana; Modesto, Everaldo Lambert; Almeida, Eloise Werle; Greguol, Márcia

    2015-01-01

    Background Cardiovascular diseases affect people worldwide. Individuals with Down Syndrome (DS) have an up to sixteen-time greater risk of mortality from cardiovascular diseases. Objective To evaluate the effects of aerobic and resistance exercises on blood pressure and hemodynamic variables of young individuals with DS. Methods A total of 29 young individuals with DS participated in the study. They were divided into two groups: aerobic training (AT) (n = 14), and resistance training (TR) (n = 15). Their mean age was 15.7 ± 2.82 years. The training program lasted 12 weeks, and had a frequency of three times a week for AT and twice a week for RT. AT was performed in treadmill/ bicycle ergometer, at an intensity between 50%-70% of the HR reserve. RT comprised nine exercises with three sets of 12 repetition-maximum. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and hemodynamic variables were assessed beat-to-beat using the Finometer device before/after the training program. Descriptive analysis, the Shapiro-Wilk test to check the normality of data, and the two-way ANOVA for repeated measures were used to compare pre- and post-training variables. The Pearson’s correlation coefficient was calculated to correlate hemodynamic variables. The SPSS version 18.0 was used with the significance level set at p < 0.05. Results After twelve weeks of aerobic and/or resistance training, significant reductions in variables SBP, DBP and MBP were observed. Conclusion This study suggests a chronic hypotensive effect of moderate aerobic and resistance exercises on young individuals with DS. PMID:26131704

  17. Dynamic Measurement of Hemodynamic Parameters and Cardiac Preload in Adults with Dengue: A Prospective Observational Study

    PubMed Central

    Thanachartwet, Vipa; Wattanathum, Anan; Sahassananda, Duangjai; Wacharasint, Petch; Chamnanchanunt, Supat; Khine Kyaw, Ei; Jittmittraphap, Akanitt; Naksomphun, Mali; Surabotsophon, Manoon; Desakorn, Varunee

    2016-01-01

    Few previous studies have monitored hemodynamic parameters to determine the physiological process of dengue or examined inferior vena cava (IVC) parameters to assess cardiac preload during the clinical phase of dengue. From January 2013 to July 2015, we prospectively studied 162 hospitalized adults with confirmed dengue viral infection using non-invasive cardiac output monitoring and bedside ultrasonography to determine changes in hemodynamic and IVC parameters and identify the types of circulatory shock that occur in patients with dengue. Of 162 patients with dengue, 17 (10.5%) experienced dengue shock and 145 (89.5%) did not. In patients with shock, the mean arterial pressure was significantly lower on day 6 after fever onset (P = 0.045) and the pulse pressure was significantly lower between days 4 and 7 (P<0.05). The stroke volume index and cardiac index were significantly decreased between days 4 and 15 and between days 5 and 8 after fever onset (P<0.05), respectively. A significant proportion of patients with dengue shock had an IVC diameter <1.5 cm and IVC collapsibility index >50% between days 4 and 5 (P<0.05). Hypovolemic shock was observed in 9 (52.9%) patients and cardiogenic shock in 8 (47.1%), with a median (interquartile range) time to shock onset of 6.0 (5.0–6.5) days after fever onset, which was the median day of defervescence. Intravascular hypovolemia occurred before defervescence, whereas myocardial dysfunction occurred on the day of defervescence until 2 weeks after fever onset. Hypovolemic shock and cardiogenic shock each occurred in approximately half of the patients with dengue shock. Therefore, dynamic measures to estimate changes in hemodynamic parameters and preload should be monitored to ensure adequate fluid therapy among patients with dengue, particularly patients with dengue shock. PMID:27196051

  18. Chronic Exercise Preserves Renal Structure and Hemodynamics in Spontaneously Hypertensive Rats

    PubMed Central

    Agarwal, Deepmala; Elks, Carrie M.; Reed, Scott D.; Mariappan, Nithya; Majid, Dewan S.A.

    2012-01-01

    Abstract Aims Exercise training (ExT) is a recommended adjunct to many pharmaceutical antihypertensive therapies. The effects of chronic ExT on the development of hypertension-induced renal injury remain unknown. We examined whether ExT would preserve renal hemodynamics and structure in the spontaneously hypertensive rat (SHR), and whether these effects were mediated by improved redox status and decreased inflammation. Normotensive WKY rats and SHR underwent moderate-intensity ExT for 16 weeks. One group of SHR animals was treated with hydralazine to investigate the pressure-dependent/independent effects of ExT. Acute renal clearance experiments were performed prior to sacrifice. Tissue free radical production rates were measured by electron paramagnetic resonance; gene and protein expression were measured by real time RT-PCR and Western blot or immunofluorescence, respectively. Plasma angiotensin II levels and kidney antioxidants were assessed. Training efficacy was assessed by citrate synthase activity assay in hind-limb muscle. Results: ExT delayed hypertension, prevented oxidative stress and inflammation, preserved antioxidant status, prevented an increase in circulating AngII levels, and preserved renal hemodynamics and structure in SHR. In addition, exercise-induced effects, at least, in part, were found to be pressure-independent. Innovation: This study is the first to provide mechanistic evidence for the renoprotective benefits of ExT in a model of hypertension. Our results demonstrate that initiation of ExT in susceptible patients can delay the development of hypertension and provide renoprotection at the functional and ultrastructural level. Conclusion: Chronic ExT preserves renal hemodynamics and structure in SHR; these effects are partially mediated by improved redox status and decreased inflammation. Antioxid. Redox Signal. 16, 139–152. PMID:21895524

  19. Effects of 12 days exposure to simulated microgravity on central circulatory hemodynamics in the rhesus monkey

    NASA Astrophysics Data System (ADS)

    Convertino, V. A.; Koenig, S. C.; Krotov, V. P.; Fanton, J. W.; Korolkov, V. I.; Trambovetsky, E. V.; Ewert, D. L.; Truzhennikov, A.; Latham, R. D.

    Central circulatory hemodynamic responses were measured before and during the initial 9 days of a 12-day 10 ° head-down tilt (HDT) in 4 flight-sized juvenile rhesus monkeys who were surgically instrumented with a variety of intrathoracic catheters and blood flow sensors to assess the effects of simulated microgravity on central circulatory hemodynamics. Each subject underwent measurements of aortic and left ventricular pressures, and aortic flow before and during HDT as well as during a passive head-up postural test before and after HDT. Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure were measured, and dP/dt and left ventricular elastance was calculated from hemodynamic measurements. The postural test consisted of 5 min of supine baseline control followed by 5 minutes of 90 ° upright tilt (HUT). Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure showed no consistent alterations during HDT. Left ventricular elastance was reduced in all animals throughout HDT, indicating that cardiac compliance was increased. HDT did not consistently alter left ventricular +dP/dt, indicating no change in cardiac contractility. Heart rate during the post-HDT HUT postural test was elevated compared to pre-HDT while post-HDT cardiac output was decreased by 52% as a result of a 54% reduction in stroke volume throughout HUT. Results from this study using an instrumented rhesus monkey suggest that exposure to microgravity may increase ventricular compliance without alterating cardiac contractility. Our project supported the notion that an invasively-instrumented animal model should be viable for use in spaceflight cardiovascular experiments to assess potential changes in myocardial function and cardiac compliance.

  20. Radionuclide assessment of peripheral hemodynamics: a new technique for measurement of forearm blood volume and flow

    SciTech Connect

    Todo, Y.; Tanimoto, M.; Yamamoto, T.; Iwasaki, T.

    1986-02-01

    A new peripheral hemodynamic measurement system using /sup 99m/Tc-labeled red blood cells has been developed. This method was carried out on 22 normal subjects, 29 with coronary artery disease, and two with dilated cardiomyopathy. Peripheral hemodynamic indices obtained from this method included forearm blood volume (FBV), venous capacity (FVC), venous capacity index (VCI), blood flow (FBF), and vascular resistance (FVR), and were compared with the central hemodynamic parameters of left ventricular filling pressure (LVFP), cardiac output (CO), and total systemic vascular resistance (TSVR) obtained with an invasive technique. The normal values were FBV 8.54 +/- 2.04 ml/100 ml; FVC 4.54 +/- 1.23 ml/100 ml; VCI 65.5 +/- 3.8%; FBF 4.26 +/- 0.56 ml/100 ml/min; and FVR 20.9 +/- 4.4 mmHg/ml/100 ml/min. These values were in good agreement with the values reported using conventional plethysmography. The 16 patients with congestive heart failure (NYHA Class II or III) showed significantly lower FBV, FVC, and FBF values and significantly higher VCI and FVR values than the healthy subjects. Capacitance vessel parameters (FBV, FVC, and VCI) and LVFP, FBF and CO, and FVR and TSVR each showed significant correlation; reproducibility was also good. The advantages of this method are (a) the detector does not come in contact with the region being measured; (b) it is possible to ascertain the absolute quantity of blood in the tissue; (c) extravasation of the plasma component can be ignored; and (d) data processing is simple.

  1. Changes in Cerebral Hemodynamics during Complex Motor Learning by Character Entry into Touch-Screen Terminals

    PubMed Central

    Sagari, Akira; Iso, Naoki; Moriuchi, Takefumi; Ogahara, Kakuya; Kitajima, Eiji; Tanaka, Koji; Tabira, Takayuki; Higashi, Toshio

    2015-01-01

    Introduction Studies of cerebral hemodynamics during motor learning have mostly focused on neurorehabilitation interventions and their effectiveness. However, only a few imaging studies of motor learning and the underlying complex cognitive processes have been performed. Methods We measured cerebral hemodynamics using near-infrared spectroscopy (NIRS) in relation to acquisition patterns of motor skills in healthy subjects using character entry into a touch-screen terminal. Twenty healthy, right-handed subjects who had no previous experience with character entry using a touch-screen terminal participated in this study. They were asked to enter the characters of a randomly formed Japanese syllabary into the touch-screen terminal. All subjects performed the task with their right thumb for 15 s alternating with 25 s of rest for 30 repetitions. Performance was calculated by subtracting the number of incorrect answers from the number of correct answers, and gains in motor skills were evaluated according to the changes in performance across cycles. Behavioral and oxygenated hemoglobin concentration changes across task cycles were analyzed using Spearman’s rank correlations. Results Performance correlated positively with task cycle, thus confirming motor learning. Hemodynamic activation over the left sensorimotor cortex (SMC) showed a positive correlation with task cycle, whereas activations over the right prefrontal cortex (PFC) and supplementary motor area (SMA) showed negative correlations. Conclusions We suggest that increases in finger momentum with motor learning are reflected in the activity of the left SMC. We further speculate that the right PFC and SMA were activated during the early phases of motor learning, and that this activity was attenuated with learning progress. PMID:26485534

  2. Bench-to-bedside review: An approach to hemodynamic monitoring--Guyton at the bedside.

    PubMed

    Magder, Sheldon

    2012-10-29

    Hemodynamic monitoring is used to identify deviations from hemodynamic goals and to assess responses to therapy. To accomplish these goals one must understand how the circulation is regulated. In this review I begin with an historical review of the work of Arthur Guyton and his conceptual understanding of the circulation and then present an approach by which Guyton's concepts can be applied at the bedside. Guyton argued that cardiac output and central venous pressure are determined by the interaction of two functions: cardiac function, which is determined by cardiac performance; and a return function, which is determined by the return of blood to the heart. This means that changes in cardiac output are dependent upon changes of one of these two functions or of both. I start with an approach based on the approximation that blood pressure is determined by the product of cardiac output and systemic vascular resistance and that cardiac output is determined by cardiac function and venous return. A fall in blood pressure with no change in or a rise in cardiac output indicates that a decrease in vascular resistance is the dominant factor. If the fall in blood pressure is due to a fall in cardiac output then the role of a change in the return function and cardiac function can be separated by the patterns of changes in central venous pressure and cardiac output. Measurement of cardiac output is a central component to this approach but until recently it was not easy to obtain and was estimated from surrogates. However, there are now a number of non-invasive devices that can give measures of cardiac output and permit the use of physiological principles to more rapidly appreciate the primary pathophysiology behind hemodynamic abnormalities and to provide directed therapy.

  3. Theoretical Analysis of the Relative Impact of Obesity on Hemodynamic Stability During Acute Hemorrhagic Shock

    PubMed Central

    Sterling, Sarah A.; Jones, Alan E.; Coleman, Thomas G.; Summers, Richard L.

    2015-01-01

    Background: Evidence suggests that morbid obesity may be an independent risk factor for adverse outcomes in patients with traumatic injuries. Objectives: In this study, a theoretic analysis using a derivation of the Guyton model of cardiovascular physiology examines the expected impact of obesity on hemodynamic changes in Mean Arterial Pressure (MAP) and Cardiac Output (CO) during Hemorrhagic Shock (HS). Patients and Methods: Computer simulation studies were used to predict the relative impact of increasing Body Mass Index (BMI) on global hemodynamic parameters during HS. The analytic procedure involved recreating physiologic conditions associated with changing BMI for a virtual subject in an In Silico environment. The model was validated for the known effect of a BMI of 30 on iliofemoral venous pressures. Then, the relative effect of changing BMI on the outcome of target cardiovascular parameters was examined during simulated acute loss of blood volume in class II hemorrhage. The percent changes in these parameters were compared between the virtual nonobese and obese subjects. Model parameter values are derived from known population distributions, producing simulation outputs that can be used in a deductive systems analysis assessment rather than traditional frequentist statistical methodologies. Results: In hemorrhage simulation, moderate increases in BMI were found to produce greater decreases in MAP and CO compared to the normal subject. During HS, the virtual obese subject had 42% and 44% greater falls in CO and MAP, respectively, compared to the nonobese subject. Systems analysis of the model revealed that an increase in resistance to venous return due to changes in intra-abdominal pressure resulting from obesity was the critical mechanism responsible for the differences. Conclusions: This study suggests that obese patients in HS may have a higher risk of hemodynamic instability compared to their nonobese counterparts primarily due to obesity

  4. Modeling ventricular interaction: a multiscale approach from sarcomere mechanics to cardiovascular system hemodynamics.

    PubMed

    Lumens, Joost; Delhaas, Tammo; Kirn, Borut; Arts, Theo

    2008-01-01

    Direct ventricular interaction via the interventricular septum plays an important role in ventricular hemodynamics and mechanics. A large amount of experimental data demonstrates that left and right ventricular pump mechanics influence each other and that septal geometry and motion depend on transmural pressure. We present a lumped model of ventricular mechanics consisting of three wall segments that are coupled on the basis of balance laws stating mechanical equilibrium at the intersection of the three walls. The input consists of left and right ventricular volumes and an estimate of septal wall geometry. Wall segment geometry is expressed as area and curvature and is related to sarcomere extension. With constitutive equations of the sarcomere, myofiber stress is calculated. The force exerted by each wall segment on the intersection, as a result of wall tension, is derived from myofiber stress. Finally, septal geometry and ventricular pressures are solved by achieving balance of forces. We implemented this ventricular module in a lumped model of the closed-loop cardiovascular system (CircAdapt model) The resulting multiscale model enables dynamic simulation of myofiber mechanics, ventricular cavity mechanics, and cardiovascular system hemodynamics. The model was tested by performing simulations with synchronous and asynchronous mechanical activation of the wall segments. The simulated results of ventricular mechanics and hemodynamics were compared with experimental data obtained before and after acute induction of left bundle branch block (LBBB) in dogs. The changes in simulated ventricular mechanics and septal motion as a result of the introduction of mechanical asynchrony were very similar to those measured in the animal experiments. In conclusion, the module presented describes ventricular mechanics including direct ventricular interaction realistically and thereby extends the physiological application range of the CircAdapt model.

  5. Hemodynamic Differences Between Central ECMO and Peripheral ECMO: A Primary CFD Study

    PubMed Central

    Gu, Kaiyun; Zhang, Ya; Gao, Bin; Chang, Yu; Zeng, Yi

    2016-01-01

    Background Veno-arterial extracorporeal membrane oxygenation (VAECMO), including central ECMO (cECMO) and peripheral ECMO (pECMO), is widely used in cardiopulmonary surgery. The outcomes and complications of both types of ECMO are quite different from each other. The hemodynamic differences among them are hypothesized as a key factor. Hence, a numerical study was conducted to test this hypothesis. Material/Methods Ideal cardiovascular models with pECMO and cECMO were established. The aortic pressure and flow rate were chosen as boundary conditions. The flow pattern, blood flow distributions, flow junction, harmonic index (HI) of blood flow, wall shear stress (WSS), and the oscillatory shear index (OSI) were calculated to evaluate the hemodynamic states. Results pECMO could achieve better upper limb and brain perfusion (0.05458 vs. 0.05062 kg/s), and worse lower limb perfusion (0.03067 vs. 0.03401 kg/s). There exist low WSS (<0.4 pa) regions at the inner and posterior wall of the aorta, and high WSS (>2 pa) region at the access of the femoral artery. These regions also have relatively high OSI value (reaching 0.45). In contrast, for cECMO, there exist high WSS at the posterior wall of the aortic arch. Conclusions The hemodynamic performances of various types of ECMO are different from each other, which maybe the key reasons for the differences in the outcomes and complications. Therefore, for pEMCO, the lower-extremity ischemia is a complication that must be considered. The type, support level, and duration of ECMO should also be carefully regulated according to the patients’ condition, as they are the important factors related to vascular complications. PMID:26938949

  6. Effects of 12 days exposure to simulated microgravity on central circulatory hemodynamics in the rhesus monkey

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Koenig, S. C.; Krotov, V. P.; Fanton, J. W.; Korolkov, V. I.; Trambovetsky, E. V.; Ewert, D. L.; Truzhennikov, A.; Latham, R. D.

    1998-01-01

    Central circulatory hemodynamic responses were measured before and during the initial 9 days of a 12-day 10 degrees head-down tilt (HDT) in 4 flight-sized juvenile rhesus monkeys who were surgically instrumented with a variety of intrathoracic catheters and blood flow sensors to assess the effects of simulated microgravity on central circulatory hemodynamics. Each subject underwent measurements of aortic and left ventricular pressures, and aortic flow before and during HDT as well as during a passive head-up postural test before and after HDT. Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure were measured, and dP/dt and left ventricular elastance was calculated from hemodynamic measurements. The postural test consisted of 5 min of supine baseline control followed by 5 minutes of 90 degrees upright tilt (HUT). Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure showed no consistent alterations during HDT. Left ventricular elastance was reduced in all animals throughout HDT, indicating that cardiac compliance was increased. HDT did not consistently alter left ventricular +dP/dt, indicating no change in cardiac contractility. Heart rate during the post-HDT HUT postural test was elevated compared to pre-HDT while post-HDT cardiac output was decreased by 52% as a result of a 54% reduction in stroke volume throughout HUT. Results from this study using an instrumented rhesus monkey suggest that exposure to microgravity may increase ventricular compliance without alternating cardiac contractility. Our project supported the notion that an invasively-instrumented animal model should be viable for use in spaceflight cardiovascular experiments to assess potential changes in myocardial function and cardiac compliance.

  7. Decreased Vertebral Artery Hemodynamics in Patients with Loss of Cervical Lordosis.

    PubMed

    Bulut, Mehmet Deniz; Alpayci, Mahmut; Şenköy, Emre; Bora, Aydin; Yazmalar, Levent; Yavuz, Alpaslan; Gülşen, İsmail

    2016-01-01

    BACKGROUND Because loss of cervical lordosis leads to disrupted biomechanics, the natural lordotic curvature is considered to be an ideal posture for the cervical spine. The vertebral arteries proceed in the transverse foramen of each cervical vertebra. Considering that the vertebral arteries travel in close anatomical relationship to the cervical spine, we speculated that the loss of cervical lordosis may affect vertebral artery hemodynamics. The aim of this study was to compare the vertebral artery values between subjects with and without loss of cervical lordosis. MATERIAL AND METHODS Thirty patients with loss of cervical lordosis and 30 controls matched for age, sex, and body mass index were included in the study. Sixty vertebral arteries in patients with loss of cervical lordosis and 60 in controls without loss of cervical lordosis were evaluated by Doppler ultrasonography. Vertebral artery hemodynamics, including lumen diameter, flow volume, peak systolic velocity, end-diastolic velocity, and resistive index, were measured, and determined values were statistically compared between the patient and the control groups. RESULTS The means of diameter (p=0.003), flow volume (p=0.002), and peak systolic velocity (p=0.014) in patients were significantly lower as compared to controls. However, there was no significant difference between the 2 groups in terms of the end-diastolic velocity (p=0.276) and resistive index (p=0.536) parameters. CONCLUSIONS The present study revealed a significant association between loss of cervical lordosis and decreased vertebral artery hemodynamics, including diameter, flow volume, and peak systolic velocity. Further studies are required to confirm these findings and to investigate their possible clinical implications. PMID:26876295

  8. Beat-rate dependent mitral flow patterns for in vitro hemodynamic applications.

    PubMed

    Vismara, Riccardo; Fiore, Gianfranco B

    2010-12-01

    The conservative surgery approach for restoring the functionality of heart valves has predominated during the last two decades, particularly for the mitral valve. In vitro pulsatile testing is a key methodology for the investigation of heart valve hemodynamics, and particularly for the ideation, validation and optimization of novel techniques in heart valve surgery. Traditionally, however, pulsatile mock loops have been developed for the study of aortic valve substitutes, and scarce attention has been paid in replicating the mitral flow patterns with due hemodynamic fidelity. In this work we provide detailed analytical expressions to produce beat-rate dependent, physiologic-like mitral flow patterns for in vitro applications. The approach we propose is based on a biomechanical analysis of the factors which govern hemodynamic changes in the mitral flow pattern, namely in terms of E and A wave contours and E/A peaks ratio, when switching from rest to mild exercise conditions. The patterns from the model we obtained were in good agreement with clinical literature data in terms of i) gradual superimposition of the E and A wave, which yielded a single peak at 96 bpm; ii) decrease in the E/A ratio with increasing heart rate; iii) amount of flow delivered by each of the two waves. The proposed method provides a physiologically representative, beat-rate dependent analytical expression of the mitral flow pattern, which can be used in in vitro hydrodynamic investigations to accurately replicate the changes that the flow waves experience when the heart rate shifts from rest to mild exercise conditions.

  9. In Vitro Validation of Patient-Specific Hemodynamic Simulations in Coronary Aneurysms Caused by Kawasaki Disease

    PubMed Central

    Kung, Ethan; Kahn, Andrew M.; Burns, Jane C.; Marsden, Alison

    2014-01-01

    To perform experimental validation of computational fluid dynamics (CFD) applied to patient specific coronary aneurysm anatomy of Kawasaki disease. We quantified hemodynamics in a patient-specific coronary artery aneurysm physical phantom under physiologic rest and exercise flow conditions. Using phase contrast MRI (PCMRI), we acquired 3-component flow velocity at two slice locations in the aneurysms. We then performed numerical simulations with the same geometry and inflow conditions, and performed qualitative and quantitative comparisons of velocities between experimental measurements and simulation results. We observed excellent qualitative agreement in flow pattern features. The quantitative spatially and temporally varying differences in velocity between PCMRI and CFD were proportional to the flow velocity. As a result, the percent discrepancy between simulation and experiment was relatively constant regardless of flow velocity variations. Through 1D and 2D quantitative comparisons, we found a 5–17% difference between measured and simulated velocities. Additional analysis assessed wall shear stress differences between deformable and rigid wall simulations. This study demonstrated that CFD produced good qualitative and quantitative predictions of velocities in a realistic coronary aneurysm anatomy under physiological flow conditions. The results provide insights on factors that may influence the level of agreement, and a set of in vitro experimental data that can be used by others to compare against CFD simulation results. The findings of this study increase confidence in the use of CFD for investigating hemodynamics in the specialized anatomy of coronary aneurysms. This provides a basis for future hemodynamics studies in patient-specific models of Kawasaki disease. PMID:25050140

  10. In Vitro Validation of Patient-Specific Hemodynamic Simulations in Coronary Aneurysms Caused by Kawasaki Disease.

    PubMed

    Kung, Ethan; Kahn, Andrew M; Burns, Jane C; Marsden, Alison

    2014-06-01

    To perform experimental validation of computational fluid dynamics (CFD) applied to patient specific coronary aneurysm anatomy of Kawasaki disease. We quantified hemodynamics in a patient-specific coronary artery aneurysm physical phantom under physiologic rest and exercise flow conditions. Using phase contrast MRI (PCMRI), we acquired 3-component flow velocity at two slice locations in the aneurysms. We then performed numerical simulations with the same geometry and inflow conditions, and performed qualitative and quantitative comparisons of velocities between experimental measurements and simulation results. We observed excellent qualitative agreement in flow pattern features. The quantitative spatially and temporally varying differences in velocity between PCMRI and CFD were proportional to the flow velocity. As a result, the percent discrepancy between simulation and experiment was relatively constant regardless of flow velocity variations. Through 1D and 2D quantitative comparisons, we found a 5-17% difference between measured and simulated velocities. Additional analysis assessed wall shear stress differences between deformable and rigid wall simulations. This study demonstrated that CFD produced good qualitative and quantitative predictions of velocities in a realistic coronary aneurysm anatomy under physiological flow conditions. The results provide insights on factors that may influence the level of agreement, and a set of in vitro experimental data that can be used by others to compare against CFD simulation results. The findings of this study increase confidence in the use of CFD for investigating hemodynamics in the specialized anatomy of coronary aneurysms. This provides a basis for future hemodynamics studies in patient-specific models of Kawasaki disease. PMID:25050140

  11. Obesity and the Role of Short Duration Submaximal Work on Cardiovascular and Cerebral Hemodynamics.

    PubMed

    Cavuoto, Lora A; Maikala, Rammohan V

    2016-01-01

    The objective of this study was to compare gas exchange, cardiac and cerebral hemodynamic responses between 10 non-obese and 10 obese men during submaximal work. With the increasing prevalence of obesity, there is a need to understand the impact of obesity on work-induced responses. Participants completed a step-wise incremental cycling until they reached 60% of their age-predicted maximum heart rate. Gas exchange, cardiac and pre-frontal cortex hemodynamic responses were simultaneously measured during rest, work, and recovery. The non-obese group reached ~43% of their predicted maximal aerobic capacity as compared to ~34% in the obese group, with the non-obese working at a relatively higher workload and for more duration than the obese. The obese had elevated baseline heart rate and reduced whole-body oxygen uptake per body weight at baseline and task termination. Other cardiac and cerebral responses, although increased from baseline, were similar between groups during submaximal effort. In the obese, during recovery oxygen uptake and heart-rate recovery were slowest; cardiac output and rate pressure product were greatest, and left ventricle ejection time was shortest. However, both groups exhibited similar cerebral hemodynamics during recovery. These finding imply that, irrespective of their low aerobic fitness, obesity does not impair myocardial performance and cerebrovascular function during graded submaximal work, however, recovery from a short duration of work was influenced by their fitness level. Since a majority of activities of daily living are performed at individual's submaximal level, understanding influence of obesity on submaximal work is critical.

  12. Obesity and the Role of Short Duration Submaximal Work on Cardiovascular and Cerebral Hemodynamics.

    PubMed

    Cavuoto, Lora A; Maikala, Rammohan V

    2016-01-01

    The objective of this study was to compare gas exchange, cardiac and cerebral hemodynamic responses between 10 non-obese and 10 obese men during submaximal work. With the increasing prevalence of obesity, there is a need to understand the impact of obesity on work-induced responses. Participants completed a step-wise incremental cycling until they reached 60% of their age-predicted maximum heart rate. Gas exchange, cardiac and pre-frontal cortex hemodynamic responses were simultaneously measured during rest, work, and recovery. The non-obese group reached ~43% of their predicted maximal aerobic capacity as compared to ~34% in the obese group, with the non-obese working at a relatively higher workload and for more duration than the obese. The obese had elevated baseline heart rate and reduced whole-body oxygen uptake per body weight at baseline and task termination. Other cardiac and cerebral responses, although increased from baseline, were similar between groups during submaximal effort. In the obese, during recovery oxygen uptake and heart-rate recovery were slowest; cardiac output and rate pressure product were greatest, and left ventricle ejection time was shortest. However, both groups exhibited similar cerebral hemodynamics during recovery. These finding imply that, irrespective of their low aerobic fitness, obesity does not impair myocardial performance and cerebrovascular function during graded submaximal work, however, recovery from a short duration of work was influenced by their fitness level. Since a majority of activities of daily living are performed at individual's submaximal level, understanding influence of obesity on submaximal work is critical. PMID:27088872

  13. Bacteriophage Procurement for Therapeutic Purposes.

    PubMed

    Weber-Dąbrowska, Beata; Jończyk-Matysiak, Ewa; Żaczek, Maciej; Łobocka, Małgorzata; Łusiak-Szelachowska, Marzanna; Górski, Andrzej

    2016-01-01

    Bacteriophages (phages), discovered 100 years ago, are able to infect and destroy only bacterial cells. In the current crisis of antibiotic efficacy, phage therapy is considered as a supplementary or even alternative therapeutic approach. Evolution of multidrug-resistant and pandrug-resistant bacterial strains poses a real threat, so it is extremely important to have the possibility to isolate new phages for therapeutic purposes. Our phage laboratory and therapy center has extensive experience with phage isolation, characterization, and therapeutic application. In this article we present current progress in bacteriophages isolation and use for therapeutic purposes, our experience in this field and its practical implications for phage therapy. We attempt to summarize the state of the art: properties of phages, the methods for their isolation, criteria of phage selection for therapeutic purposes and limitations of their use. Perspectives for the use of genetically engineered phages to specifically target bacterial virulence-associated genes are also briefly presented. PMID:27570518

  14. Bacteriophage Procurement for Therapeutic Purposes

    PubMed Central

    Weber-Dąbrowska, Beata; Jończyk-Matysiak, Ewa; Żaczek, Maciej; Łobocka, Małgorzata; Łusiak-Szelachowska, Marzanna; Górski, Andrzej

    2016-01-01

    Bacteriophages (phages), discovered 100 years ago, are able to infect and destroy only bacterial cells. In the current crisis of antibiotic efficacy, phage therapy is considered as a supplementary or even alternative therapeutic approach. Evolution of multidrug-resistant and pandrug-resistant bacterial strains poses a real threat, so it is extremely important to have the possibility to isolate new phages for therapeutic purposes. Our phage laboratory and therapy center has extensive experience with phage isolation, characterization, and therapeutic application. In this article we present current progress in bacteriophages isolation and use for therapeutic purposes, our experience in this field and its practical implications for phage therapy. We attempt to summarize the state of the art: properties of phages, the methods for their isolation, criteria of phage selection for therapeutic purposes and limitations of their use. Perspectives for the use of genetically engineered phages to specifically target bacterial virulence-associated genes are also briefly presented. PMID:27570518

  15. Paradoxical gas embolism after SCUBA diving: hemodynamic changes studied by echocardiography.

    PubMed

    Boussuges, A; Pontier, J M; Schmid, B; Dussault, C

    2014-02-01

    Hemodynamic changes induced by self-contained underwater breathing apparatus diving were investigated using Doppler echocardiography. We detected circulating bubbles in both right and left cavities of the heart and in the cerebral circulation in two divers with a large patent foramen ovale. A reduction in the left ventricular preload was suggested by echocardiographic measurements. The decreased cardiac preload was paralleled to a lower stroke volume and cardiac output. These findings were also observed in divers with no evidence of circulating bubbles. In these subjects, pulmonary vascular resistances remained unchanged while an increase was observed in the two divers with arterial bubbles. This increase could promote right-to-left shunting.

  16. Separation of superficial and cerebral hemodynamics using a single distance time-domain NIRS measurement

    PubMed Central

    Jelzow, Alexander; Wabnitz, Heidrun; Tachtsidis, Ilias; Kirilina, Evgeniya; Brühl, Rüd