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Sample records for systemic hemodynamic derangement

  1. Deranged Exams

    ERIC Educational Resources Information Center

    Spivey, Michael Z.

    2010-01-01

    This article discusses a triangle of numbers that are related to the derangement numbers. These numbers satisfy a Pascal-like recurrence relation with subtraction instead of addition. We describe how they relate to numbers studied by other authors and use them to generalize Euler's famous recurrence relation for the derangement numbers.

  2. Hemodynamics

    PubMed Central

    Secomb, Timothy W.

    2016-01-01

    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 non-uniform 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

  3. Derangements of potassium.

    PubMed

    Medford-Davis, Laura; Rafique, Zubaid

    2014-05-01

    Changes in potassium elimination, primarily due to the renal and GI systems, and shifting potassium between the intracellular and extracellular spaces cause potassium derangement. Symptoms are vague, but can be cardiac, musculoskeletal, or gastrointestinal. There are no absolute guidelines for when to treat, but it is generally recommended when the patient is symptomatic or has ECG changes. Treatment of hyperkalemia includes cardiac membrane stabilization with IV calcium, insulin and beta-antagonists to push potassium intracellularly, and dialysis. Neither sodium bicarbonate nor kayexelate are recommended. Treatment of symptomatic hypokalemia consists of PO or IV repletion with potassium chloride and magnesium sulfate.

  4. The multiple parameter hemodynamic imaging system based on ARM

    NASA Astrophysics Data System (ADS)

    Tang, Xuejun; He, Heng; Jiang, Chao; Li, Pengcheng; Luo, Qingming

    2008-12-01

    Optical imaging with high resolution is significant to reveal the functional activities of brain and the mechanism of disease, and has grown into a diverse field. The high-resolution multi-parameters optical imaging system which combines the laser speckle contrast imaging method and optical intrinsic signal imaging method can obtain more hemodynamic information in cortex simultaneously. However, most of current optical imaging systems use He-Ne laser and mercury xenon arc lamp as the light source. Meanwhile, the control unit of the system which includes a personal computer, is not portable. In this paper, we develop a multiple parameters hemodynamic imaging system based on ARM. To make the system more compact, three wavelengths light-emitting diode and laser diode as imaging illuminants were adopted. In addition, the real-time embedded operation system (μC/OS-II) and embedded Graphic User Interface (μC/GUI) were introduced. Animal experimental results also show that changes in oxyhemoglobin, deoxyhemoglobin, total hemoglobin concentration and cerebral blood flow during Cortical Spreading Depression can be simultaneously accessed using this optical imaging system based on embedded ARM.

  5. [Effects of phenibut on parameters of cerebral hemodynamics in swimmers with dysadaptation syndrome and various types of systemic hemodynamics].

    PubMed

    Likhodeeva, V A; Spasov, A A; Isupov, I B; Mandrikov, V B

    2010-08-01

    Administration of phenibut (0.25 g) during 4 weeks as a means of rehabilitation promoted optimization of the biochemical status and cerebral blood circulation in swimmers with various types of systemic hemodynamics, which were examined 20 minutes after warm-up.

  6. 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.

  7. Hemodynamically Driven Vein Graft Remodeling: A Systems Biology Approach

    PubMed Central

    Berceli, Scott A.; Tran-Son-Tay, Roger; Garbey, Marc; Jiang, Zhihua

    2011-01-01

    Despite intense investigation over several decades to understand the mechanisms of vein graft failure, few therapeutic modalities have emerged. Emphasis using standard reductionist approaches has been focused on cataloging the components involved in the early events following vein graft implantation, but limited insight has been gained in understanding the dynamic interaction of these components. We propose that the application of systems theory offers the opportunity for significant advances in this area. Focused on modeling the dynamic relationships that define living organisms, systems biology provides the necessary tools to further our understanding of the complex series of overlapping biologic events on surgical implantation of the vein graft. Through the use of ordinary differential equation and agent-based modeling techniques, we present our ongoing efforts to define the nonlinear interactions between hemodynamics and vascular adaptation. PMID:19426605

  8. 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

  9. 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

  10. Augmented expression and secretion of adipose-derived pigment epithelium-derived factor does not alter local angiogenesis or contribute to the development of systemic metabolic derangements.

    PubMed

    Lakeland, Thomas V; Borg, Melissa L; Matzaris, Maria; Abdelkader, Amany; Evans, Roger G; Watt, Matthew J

    2014-06-15

    Impaired coupling of adipose tissue expansion and vascularization is proposed to lead to adipocyte hypoxia and inflammation, which in turn contributes to systemic metabolic derangements. Pigment epithelium-derived factor (PEDF) is a powerful antiangiogenic factor that is secreted by adipocytes, elevated in obesity, and implicated in the development of insulin resistance. We explored the angiogenic and metabolic role of adipose-derived PEDF through in vivo studies of mice with overexpression of PEDF in adipocytes (PEDF-aP2). PEDF expression in white adipocytes and PEDF secretion from adipose tissue was increased in transgenic mice, but circulating levels of PEDF were not increased. Overexpression of PEDF did not alter vascularization, the partial pressure of O2, cellular hypoxia, or gene expression of inflammatory markers in adipose tissue. Energy expenditure and metabolic substrate utilization, body mass, and adiposity were not altered in PEDF-aP2 mice. Whole body glycemic control was normal as assessed by glucose and insulin tolerance tests, and adipocyte-specific glucose uptake was unaffected by PEDF overexpression. Adipocyte lipolysis was increased in PEDF-aP2 mice and associated with increased adipose triglyceride lipase and decreased perilipin 1 expression. Experiments conducted in mice rendered obese by high-fat feeding showed no differences between PEDF-aP2 and wild-type mice for body mass, adiposity, whole body energy expenditure, glucose tolerance, or adipose tissue oxygenation. Together, these data indicate that adipocyte-generated PEDF enhances lipolysis but question the role of PEDF as a major antiangiogenic or proinflammatory mediator in adipose tissue in vivo.

  11. PGC-1α Deficiency Causes Multi-System Energy Metabolic Derangements: Muscle Dysfunction, Abnormal Weight Control and Hepatic Steatosis

    PubMed Central

    Leone, Teresa C; Lehman, John J; Finck, Brian N; Schaeffer, Paul J; Wende, Adam R; Boudina, Sihem; Courtois, Michael; Wozniak, David F; Sambandam, Nandakumar; Bernal-Mizrachi, Carlos; Chen, Zhouji; O. Holloszy, John; Medeiros, Denis M; Schmidt, Robert E; Saffitz, Jeffrey E; Abel, E. Dale; Semenkovich, Clay F

    2005-01-01

    The gene encoding the transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) was targeted in mice. PGC-1α null (PGC-1α−/−) mice were viable. However, extensive phenotyping revealed multi-system abnormalities indicative of an abnormal energy metabolic phenotype. The postnatal growth of heart and slow-twitch skeletal muscle, organs with high mitochondrial energy demands, is blunted in PGC-1α−/− mice. With age, the PGC-1α−/− mice develop abnormally increased body fat, a phenotype that is more severe in females. Mitochondrial number and respiratory capacity is diminished in slow-twitch skeletal muscle of PGC-1α−/− mice, leading to reduced muscle performance and exercise capacity. PGC-1α−/− mice exhibit a modest diminution in cardiac function related largely to abnormal control of heart rate. The PGC-1α−/− mice were unable to maintain core body temperature following exposure to cold, consistent with an altered thermogenic response. Following short-term starvation, PGC-1α−/− mice develop hepatic steatosis due to a combination of reduced mitochondrial respiratory capacity and an increased expression of lipogenic genes. Surprisingly, PGC-1α−/− mice were less susceptible to diet-induced insulin resistance than wild-type controls. Lastly, vacuolar lesions were detected in the central nervous system of PGC-1α−/− mice. These results demonstrate that PGC-1α is necessary for appropriate adaptation to the metabolic and physiologic stressors of postnatal life. PMID:15760270

  12. Decision support for hemodynamic management: from graphical displays to closed loop systems.

    PubMed

    Michard, Frederic

    2013-10-01

    The way hemodynamic therapies are delivered today in anesthesia and critical care is suboptimal. Hemodynamic variables are not always understood correctly and used properly. The adoption of hemodynamic goal-directed strategies, known to be clinically useful, is poor. Ensuring therapies are delivered effectively is the goal of decision support tools and closed loop systems. Graphical displays (metaphor screens) may help clinicians to better capture and integrate the multivariable hemodynamic information. This may result in faster and more accurate diagnosis and therapeutic decisions. Graphical displays (target screens) have the potential to increase adherence to goal-directed strategies and ultimately improve patients' outcomes, but this remains to be confirmed by prospective studies. Closed loop systems are the ultimate solution to ensure therapies are delivered. However, most therapeutic decisions cannot be based on a limited number of output variables. Therefore, one should focus on the development of systems designed to relieve clinicians from very simple and repetitive tasks. Whether intraoperative goal-directed fluid therapy may be one of these tasks remains to be evaluated.

  13. Deranged sodium to sudden death

    PubMed Central

    Clancy, Colleen E; Chen-Izu, Ye; Bers, Donald M; Belardinelli, Luiz; Boyden, Penelope A; Csernoch, Laszlo; Despa, Sanda; Fermini, Bernard; Hool, Livia C; Izu, Leighton; Kass, Robert S; Lederer, W Jonathan; Louch, William E; Maack, Christoph; Matiazzi, Alicia; Qu, Zhilin; Rajamani, Sridharan; Rippinger, Crystal M; Sejersted, Ole M; O'Rourke, Brian; Weiss, James N; Varró, András; Zaza, Antonio

    2015-01-01

    In February 2014, a group of scientists convened as part of the University of California Davis Cardiovascular Symposium to bring together experimental and mathematical modelling perspectives and discuss points of consensus and controversy on the topic of sodium in the heart. This paper summarizes the topics of presentation and discussion from the symposium, with a focus on the role of aberrant sodium channels and abnormal sodium homeostasis in cardiac arrhythmias and pharmacotherapy from the subcellular scale to the whole heart. Two following papers focus on Na+ channel structure, function and regulation, and Na+/Ca2+ exchange and Na+/K+ ATPase. The UC Davis Cardiovascular Symposium is a biannual event that aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The focus on Na+ in the 2014 symposium stemmed from the multitude of recent studies that point to the importance of maintaining Na+ homeostasis in the heart, as disruption of homeostatic processes are increasingly identified in cardiac disease states. Understanding how disruption in cardiac Na+-based processes leads to derangement in multiple cardiac components at the level of the cell and to then connect these perturbations to emergent behaviour in the heart to cause disease is a critical area of research. The ubiquity of disruption of Na+ channels and Na+ homeostasis in cardiac disorders of excitability and mechanics emphasizes the importance of a fundamental understanding of the associated mechanisms and disease processes to ultimately reveal new targets for human therapy. PMID:25772289

  14. 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.

  15. An Integrative Model of the Cardiovascular System Coupling Heart Cellular Mechanics with Arterial Network Hemodynamics

    PubMed Central

    Kim, Young-Tae; Lee, Jeong Sang; Youn, Chan-Hyun; Choi, Jae-Sung

    2013-01-01

    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. PMID:23960442

  16. Topology and hemodynamics of the cortical cerebrovascular system

    PubMed Central

    Hirsch, Sven; Reichold, Johannes; Schneider, Matthias; Székely, Gábor; Weber, Bruno

    2012-01-01

    The cerebrovascular system continuously delivers oxygen and energy substrates to the brain, which is one of the organs with the highest basal energy requirement in mammals. Discontinuities in the delivery lead to fatal consequences for the brain tissue. A detailed understanding of the structure of the cerebrovascular system is important for a multitude of (patho-)physiological cerebral processes and many noninvasive functional imaging methods rely on a signal that originates from the vasculature. Furthermore, neurodegenerative diseases often involve the cerebrovascular system and could contribute to neuronal loss. In this review, we focus on the cortical vascular system. In the first part, we present the current knowledge of the vascular anatomy. This is followed by a theory of topology and its application to vascular biology. We then discuss possible interactions between cerebral blood flow and vascular topology, before summarizing the existing body of the literature on quantitative cerebrovascular topology. PMID:22472613

  17. Hemodynamic actions and mechanisms of systemically administered α-MSH analogs in mice.

    PubMed

    Rinne, Petteri; Tikka, Sanna; Mäkelä, Satu; Streng, Tomi; Savontaus, Eriika

    2012-11-01

    α-Melanocyte-stimulating hormone (α-MSH) regulates important physiological functions including energy homeostasis and inflammation. Potent analogs of α-MSH, [Nle(4), D-Phe(7)]-α-MSH (NDP-α-MSH) and melanotan-II (MT-II), are widely used in pharmacological studies, but the hemodynamic effects associated with their systemic administration have not been thoroughly examined. Therefore, we investigated the hemodynamic actions of these compounds in anesthetized and conscious C57Bl/6N mice using peripheral routes of administration. NDP-α-MSH and MT-II induced mild changes in blood pressure and heart rate in anesthetized mice compared to the effects observed in conscious mice, suggesting that anesthesia distorts the hemodynamic actions of α-MSH analogs. In conscious mice, NDP-α-MSH and MT-II increased blood pressure and heart rate in a dose-dependent manner, but the tachycardic effect was more prominent than the pressor effect. Pretreatment with the melanocortin (MC) 3/4 receptor antagonist SHU9119 abolished these hemodynamic effects. Furthermore, the blockade of β(1)-adrenoceptors with metoprolol prevented the pressor effect and partly the tachycardic action of α-MSH analogs, while the ganglionic blocker hexamethonium abrogated completely the difference in heart rate between vehicle and α-MSH treatments. These findings suggest that the pressor effect is primarily caused by augmentation of cardiac sympathetic activity, but the tachycardic effect seems to involve withdrawal of vagal tone in addition to sympathetic activation. In conclusion, the present results indicate that systemic administration of α-MSH analogs elevates blood pressure and heart rate via activation of MC(3/4) receptor pathways. These effects and the consequent increase in cardiac workload should be taken into account when using α-MSH analogs via peripheral routes of administration.

  18. Systemic Hypertension, Headache, and Ocular Hemodynamics: A New Hypothesis

    PubMed Central

    Gupta, Vinod Kumar

    2006-01-01

    The association between systemic hypertension and headache remains controversial and its pathophysiologic basis is uncertain. A rather characteristic early-morning pulsating headache is commonly seen in hypertensive patients, and a recent meta-analysis supports the link between these 2 entities. Epidemiologic evidence has paradoxically suggested a negative association between hypertension and headache. Unpredictable clinical association between severe hypertension and headache indicates that another cranial perfusion-related variable exerts a critical role. Neuroanatomically, head and neck pain primarily involves the ophthalmic division of the trigeminal nerve (V1). A link between systemic hypertension, pulsatile choroidal blood flow (CBF), and intraocular pressure (IOP) has been established. I propose that a trait ocular sympathetic hypofunction permits rapid episodic ocular choroidal overperfusion that stretches the ocular globe in the cohort of hypertensive patients with headache. Rapid distension of the pain-sensitive corneoscleral envelope can stimulate corneoscleral and iridial pain-sensitive V1 nerve endings and generate headache. Ocular tamponade function physiologically limits choroidal overperfusion. A higher basal IOP in some patients with moderate-to-severe hypertension may dampen pulsatile CBF and account for the negative epidemiologic link between sustained systemic hypertension and headache. Besides activation of the baroreceptor reflex, the association of hypalgesia with hypertension probably involves activation of the vasopressin-endorphin adaptive system consequent to mechanical stimulation of V1. The analogy between hypertensive headache and angle-closure glaucoma is rather limited because typical ocular and visual signs and symptoms of angle-closure glaucoma are not seen in hypertension-related headache. Hypertensive crises, including those associated with pheochromocytoma, are not accompanied by attacks of angle-closure glaucoma. Glaucoma is

  19. A novel system identification technique for improved wearable hemodynamics assessment.

    PubMed

    Wiens, Andrew D; Inan, Omer T

    2015-05-01

    Recent advances have led to renewed interest in ballistocardiography (BCG), a noninvasive measure of the small movements of the body due to cardiovascular events. A broad range of platforms have been developed and verified for BCG measurement including beds, chairs, and weighing scales: while the body is coupled to such a platform, the cardiogenic movements are measured. Wearable BCG, measured with an accelerometer affixed to the body, may enable continuous, or more regular, monitoring during the day; however, the signals from such wearable BCGs represent local or distal accelerations of skin and tissue rather than the whole body. In this paper, we propose a novel method to reconstruct the BCG measured with a weighing scale (WS BCG) from a wearable sensor via a training step to remove these local effects. Preliminary validation of this method was performed with 15 subjects: the wearable sensor was placed at three locations on the surface of the body while WS BCG measurements were recorded simultaneously. A regularized system identification approach was used to reconstruct the WS BCG from the wearable BCG. Preliminary results suggest that the relationship between local and central disturbances is highly dependent on both the individual and the location where the accelerometer is placed on the body and that these differences can be resolved via calibration to accurately measure changes in cardiac output and contractility from a wearable sensor. Such measurements could be highly effective, for example, for improved monitoring of heart failure patients at home.

  20. A Novel System Identification Technique for Improved Wearable Hemodynamics Assessment

    PubMed Central

    Wiens, Andrew D.; Inan, Omer T.

    2015-01-01

    Recent advances have led to renewed interest in ballistocardiography (BCG), a non-invasive measure of the small reaction forces on the body from cardiovascular events. A broad range of platforms have been developed and verified for BCG measurement including beds, chairs, and weighing scales: while the body is coupled to such a platform, the cardiogenic movements of the center-of-mass (COM) are measured. Wearable BCG, measured with an accelerometer affixed to the body, may enable continuous, or more regular, monitoring during the day; however, the signals from such wearable BCGs represent local or distal accelerations of skin and tissue rather than the displacement of the body's COM. In this paper we propose a novel method to reconstruct the COM BCG from a wearable sensor via a training step to remove these local effects. Preliminary validation of this method was performed with fifteen subjects: the wearable sensor was placed at three locations on the surface of the body while COM BCG measurements were recorded simultaneously with a modified weighing scale. A regularized system identification approach was used to reconstruct the COM BCG from the wearable signal. Preliminary results suggest that the relationship between local and central forces is highly dependent on both the individual and the location where the wearable sensor is placed on the body and that these differences can be resolved via calibration to accurately measure changes in cardiac output and contractility from a wearable sensor. Such measurements could be highly effective, for example, for improved monitoring of heart failure patients at home. PMID:25561589

  1. CMOS Image Sensor and System for Imaging Hemodynamic Changes in Response to Deep Brain Stimulation.

    PubMed

    Zhang, Xiao; Noor, Muhammad S; McCracken, Clinton B; Kiss, Zelma H T; Yadid-Pecht, Orly; Murari, Kartikeya

    2016-06-01

    Deep brain stimulation (DBS) is a therapeutic intervention used for a variety of neurological and psychiatric disorders, but its mechanism of action is not well understood. It is known that DBS modulates neural activity which changes metabolic demands and thus the cerebral circulation state. However, it is unclear whether there are correlations between electrophysiological, hemodynamic and behavioral changes and whether they have any implications for clinical benefits. In order to investigate these questions, we present a miniaturized system for spectroscopic imaging of brain hemodynamics. The system consists of a 144 ×144, [Formula: see text] pixel pitch, high-sensitivity, analog-output CMOS imager fabricated in a standard 0.35 μm CMOS process, along with a miniaturized imaging system comprising illumination, focusing, analog-to-digital conversion and μSD card based data storage. This enables stand alone operation without a computer, nor electrical or fiberoptic tethers. To achieve high sensitivity, the pixel uses a capacitive transimpedance amplifier (CTIA). The nMOS transistors are in the pixel while pMOS transistors are column-parallel, resulting in a fill factor (FF) of 26%. Running at 60 fps and exposed to 470 nm light, the CMOS imager has a minimum detectable intensity of 2.3 nW/cm(2) , a maximum signal-to-noise ratio (SNR) of 49 dB at 2.45 μW/cm(2) leading to a dynamic range (DR) of 61 dB while consuming 167 μA from a 3.3 V supply. In anesthetized rats, the system was able to detect temporal, spatial and spectral hemodynamic changes in response to DBS.

  2. The complex distribution of arterial system mechanical properties, pulsatile hemodynamics, and vascular stresses emerges from three simple adaptive rules.

    PubMed

    Nguyen, Phuc H; Coquis-Knezek, Sarah F; Mohiuddin, Mohammad W; Tuzun, Egemen; Quick, Christopher M

    2015-03-01

    Arterial mechanical properties, pulsatile hemodynamic variables, and mechanical vascular stresses vary significantly throughout the systemic arterial system. Although the fundamental principles governing pulsatile hemodynamics in elastic arteries are widely accepted, a set of rules governing stress-induced adaptation of mechanical properties can only be indirectly inferred from experimental studies. Previously reported mathematical models have assumed mechanical properties adapt to achieve an assumed target stress "set point." Simultaneous prediction of the mechanical properties, hemodynamics, and stresses, however, requires that equilibrium stresses are not assumed a priori. Therefore, the purpose of this work was to use a "balance point" approach to identify the simplest set of universal adaptation rules that simultaneously predict observed mechanical properties, hemodynamics, and stresses throughout the human systemic arterial system. First, we employed a classical systemic arterial system model with 121 arterial segments and removed all parameter values except vessel lengths and peripheral resistances. We then assumed vessel radii increase with endothelial shear stress, wall thicknesses increase with circumferential wall stress, and material stiffnesses decrease with circumferential wall stress. Parameters characterizing adaptive responses were assumed to be identical in all arterial segments. Iteratively predicting local mechanical properties, hemodynamics, and stresses reproduced five trends observed when traversing away from the aortic root towards the periphery: decrease in lumen radii, wall thicknesses, and pulsatile flows and increase in wall stiffnesses and pulsatile pressures. The extraordinary complexity of the systemic arterial system can thus arise from independent adaptation of vessels to local stresses characterized by three simple adaptive rules.

  3. Effect of ROS Inhalation on Systemic and Local Hemodynamics in Rats.

    PubMed

    Martusevich, A K; Peretyagin, S P; Martusevich, A A; Peretyagin, P V

    2016-09-01

    The effects of inhalation of singlet oxygen mixture, dry and humidified ozone-oxygen mixture, and ozonated oils on heart rate variability as well as on the rate and control mechanisms of microcirculation were examined in rats. The most optimal were the responses of systemic and regional hemodynamics to inhalation of the gas produced by a generator of singlet oxygen and humidified ozone-oxygen mixtures. Singlet oxygen stabilized the cardiac rhythm and augmented microcirculation via activation of "internal" (endothelial and neurogenic) regulatory mechanisms.

  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. Measurement system for an in-vitro characterization of the biomechanics and hemodynamics of arterial bifurcations

    NASA Astrophysics Data System (ADS)

    Suárez-Bagnasco, D.; Balay, G.; Cymberknop, L.; Armentano, R. L.; Negreira, C. A.

    2013-03-01

    Arterial behaviour in-vivo is influenced, amongst other factors, by the interaction between blood flow and the arterial wall endothelium, and the biomechanical properties of the arterial wall. This interaction plays an important role in pathogenic mechanisms of cardiovascular diseases such as atherosclerosis and arteriosclerosis. To quantify these interactions both from biomechanical and hemodynamical standpoints, a complete characterization and modelling of the arterial wall, blood flow, shear wall and circumferential wall stresses are needed. The development of a new multi-parameter measurement system (distances, pressures, flows, velocity profiles, temperature, viscosity) for an in-vitro characterization of the biomechanics and hemodynamics in arterial bifurcations (specially in carotid bifurcations) is described. This set-up represents an improvement relative to previous set-ups developed by the group FCIEN-FMED and is presently under development. Main subsystems interactions and environment-system interactions were identified and compensated to improve system's performance. Several interesting problems related with signal acquisition using a variety of sensors and some experimental results are shown and briefly discussed. Experimental data allow construction of meshes and parameter estimation of the biomechanical properties of the arterial wall, as well as boundary conditions, all suitable to be employed in CFD and FSI numerical simulation.

  6. Effects of slow deep breathing at high altitude on oxygen saturation, pulmonary and systemic hemodynamics.

    PubMed

    Bilo, Grzegorz; Revera, Miriam; Bussotti, Maurizio; Bonacina, Daniele; Styczkiewicz, Katarzyna; Caldara, Gianluca; Giglio, Alessia; Faini, Andrea; Giuliano, Andrea; Lombardi, Carolina; Kawecka-Jaszcz, Kalina; Mancia, Giuseppe; Agostoni, Piergiuseppe; Parati, Gianfranco

    2012-01-01

    Slow deep breathing improves blood oxygenation (Sp(O2)) and affects hemodynamics in hypoxic patients. We investigated the ventilatory and hemodynamic effects of slow deep breathing in normal subjects at high altitude. We collected data in healthy lowlanders staying either at 4559 m for 2-3 days (Study A; N = 39) or at 5400 m for 12-16 days (Study B; N = 28). Study variables, including Sp(O2) and systemic and pulmonary arterial pressure, were assessed before, during and after 15 minutes of breathing at 6 breaths/min. At the end of slow breathing, an increase in Sp(O2) (Study A: from 80.2±7.7% to 89.5±8.2%; Study B: from 81.0±4.2% to 88.6±4.5; both p<0.001) and significant reductions in systemic and pulmonary arterial pressure occurred. This was associated with increased tidal volume and no changes in minute ventilation or pulmonary CO diffusion. Slow deep breathing improves ventilation efficiency for oxygen as shown by blood oxygenation increase, and it reduces systemic and pulmonary blood pressure at high altitude but does not change pulmonary gas diffusion.

  7. The effect of indomethacin on systemic and renal hemodynamics in neonatal piglets during experimental endotoxemia.

    PubMed

    Furtado, Nicholas; Beier, Ulf H; Gorla, Sema Rao; Fornell, Linda; Lumpaopong, Adisorn; Radhakrishnan, Jayant; John, Eunice

    2008-08-01

    Systemic and renal hemodynamics are affected by prostaglandin production during endotoxemia. To study indomethacin effects on endotoxinemia in a neonatal piglet model, sixteen 7-10 day old piglets were anesthetized, ventilated, and catheterized. Mean arterial pressure (MAP), heart rate (HR), and urine output were continuously monitored. Endotoxin (0.06 mcg/kg) was injected after baseline measurements. We studied two groups with either endotoxinemia alone (n = 7) or an additional indomethacin infusion (0.2 mg/kg per h, n = 9). HR, MAP, renal blood flow (RBF), systemic and renal vascular resistance (SVR, RVR), cardiac index (CI), and glomerular filtration rate (GFR), were obtained at baseline, at 1, 2 and 3 h. We observed a drop in CI and an increase in SVR and HR within 3 h of endotoxinemia, while MAP remained unchanged. These effects were prevented by indomethacin. RVR was not altered significantly. Endotoxinemia triggered a drop of RBF in both control (P < 0.01) and intervention group (P < 0.05). In the intervention group, drop of GFR, urine volume, and paraaminohippuric acid clearance were apparent signs of nephrotoxicity (P < 0.01, <0.05, and <0.01). In conclusion, indomethacin maintains hemodynamic parameters during endotoxinemia at the expense of nephrotoxicity. We speculate that indomethacin counteracts the renoprotective effect of prostaglandins.

  8. Hypertrophic response to hemodynamic overload: role of load vs. renin-angiotensin system activation

    NASA Technical Reports Server (NTRS)

    Koide, M.; Carabello, B. A.; Conrad, C. C.; Buckley, J. M.; DeFreyte, G.; Barnes, M.; Tomanek, R. J.; Wei, C. C.; Dell'Italia, L. J.; Cooper, G. 4th; Zile, M. R.

    1999-01-01

    Myocardial hypertrophy is one of the basic mechanisms by which the heart compensates for hemodynamic overload. The mechanisms by which hemodynamic overload is transduced by the cardiac muscle cell and translated into cardiac hypertrophy are not completely understood. Candidates include activation of the renin-angiotensin system (RAS) and angiotensin II receptor (AT1) stimulation. In this study, we tested the hypothesis that load, independent of the RAS, is sufficient to stimulate cardiac growth. Four groups of cats were studied: 14 normal controls, 20 pulmonary artery-banded (PAB) cats, 7 PAB cats in whom the AT1 was concomitantly and continuously blocked with losartan, and 8 PAB cats in whom the angiotensin-converting enzyme (ACE) was concomitantly and continuously blocked with captopril. Losartan cats had at least a one-log order increase in the ED50 of the blood pressure response to angiotensin II infusion. Right ventricular (RV) hypertrophy was assessed using the RV mass-to-body weight ratio and ventricular cardiocyte size. RV hemodynamic overload was assessed by measuring RV systolic and diastolic pressures. Neither the extent of RV pressure overload nor RV hypertrophy that resulted from PAB was affected by AT1 blockade with losartan or ACE inhibition with captopril. RV systolic pressure was increased from 21 +/- 3 mmHg in normals to 68 +/- 4 mmHg in PAB, 65 +/- 5 mmHg in PAB plus losartan and 62 +/- 3 mmHg in PAB plus captopril. RV-to-body weight ratio increased from 0.52 +/- 0.04 g/kg in normals to 1.11 +/- 0.06 g/kg in PAB, 1.06 +/- 0.06 g/kg in PAB plus losartan and 1.06 +/- 0.06 g/kg in PAB plus captopril. Thus 1) pharmacological modulation of the RAS with losartan and captopril did not change the extent of the hemodynamic overload or the hypertrophic response induced by PAB; 2) neither RAS activation nor angiotensin II receptor stimulation is an obligatory and necessary component of the signaling pathway that acts as an intermediary coupling load to the

  9. A method for discriminating systemic and cortical hemodynamic changes by time domain fNIRS

    NASA Astrophysics Data System (ADS)

    Zucchelli, Lucia; Spinelli, Lorenzo; Contini, Davide; Re, Rebecca; Torricelli, Alessandro

    2013-06-01

    Functional near-infrared spectroscopy (fNIRS) is a non-invasive optical technique able to measure hemodynamic response in the brain cortex. Among the different approaches the fNIRS can be based on, the time resolved one allows a straightforward relationship between the photon detection time and its path within the medium, improving the discrimination of the information content relative to the different layers the tissues are composed of. Thus absorption and scattering properties of the probed tissue can be estimated, and from them the oxy- and deoxy-hemoglobin concentration. However, an open issue in the optical imaging studies is still the accuracy in separating the superficial hemodynamic changes from those happening in deeper regions of the head and more likely involving the cerebral cortex. In fact a crucial point is the precise estimate of the time dependent pathlength spent by photons within the perturbed medium. A novel method for the calculus of the absorption properties in time domain fNIRS, based on a refined computation of photon pathlength in multilayered media, is proposed. The method takes into account the non-ideality of the measurement system (its instrument response function) and the heterogeneous structure of the head. The better accuracy in computing the optical pathlength can improve the NIRS data analysis, especially for the deeper layer. Simulations and preliminary analysis on in vivo data have been performed to validate the method and are here presented.

  10. Systemic Hemodynamic Atherothrombotic Syndrome and Resonance Hypothesis of Blood Pressure Variability: Triggering Cardiovascular Events

    PubMed Central

    2016-01-01

    Blood pressure (BP) exhibits different variabilities and surges with different time phases, from the shortest beat-by-beat to longest yearly changes. We hypothesized that the synergistic resonance of these BP variabilites generates an extraordinarily large dynamic surge in BP and triggers cardiovascular events (the resonance hypothesis). The power of pulses is transmitted to the peripheral sites without attenuation by the large arteries, in individuals with stiffened arteries. Thus, the effect of a BP surge on cardiovascular risk would be especially exaggerated in high-risk patients with vascular disease. Based on this concept, our group recently proposed a new theory of systemic hemodynamic atherothromboltic syndrome (SHATS), a vicious cycle of hemodynamic stress and vascular disease that advances organ damage and triggers cardiovascular disease. Clinical phenotypes of SHATS are large-artery atherothombotic diseases such as stroke, coronary artery disease, and aortic and pheripheral artery disease; small-artery diseases, and microcirculation-related disease such as vascular cognitive dysfunction, heart failure, and chronic kidney disease. The careful consideration of BP variability and vascular diseases such as SHATS, and the early detection and management of SHATS, will achieve more effective individualized cardiovascular protection. In the near future, information and communication technology-based 'anticipation medicine' predicted by the changes of individual BP values could be a promising approach to achieving zero cardiovascular events. PMID:27482253

  11. Systemic and coronary hemodynamic actions and left ventricular functional effects of levosimendan in conscious dogs.

    PubMed

    Harkin, C P; Pagel, P S; Tessmer, J P; Warltier, D C

    1995-08-01

    We examined the effects of levosimendan, a new myofilament Ca2+ sensitizer with phosphodiesterase (PDE)-inhibiting properties, on systemic and coronary hemodynamics and left ventricular (LV) systolic and diastolic function in conscious dogs with intact and blocked autonomic nervous system (ANS) reflexes. Twenty experiments were conducted in 10 dogs chronically instrumented for measurement of aortic and LV pressure, the peak rate of increase and decrease in LV pressure (+dP/dtmax and -dP/dtmin), subendocardial segment length, diastolic coronary blood flow (CBF) velocity, and cardiac output (CO). The slope (Mw) of the regional preload recruitable stroke work relation was used to assess myocardial contractility. Diastolic function was evaluated by -dP/dtmin, a time constant of isovolumic relaxation (tau), maximum segment lengthening velocity during rapid ventricular filling (dL/dtmax), and a regional chamber stiffness constant (Kp). Dogs were randomly assigned to receive levosimendan (0.5, 1.0, 2.0, and 4.0 micrograms.kg-1.min-1) with or without ANS blockade. On separate experimental days, systemic and coronary hemodynamics and LV pressure-segment length diagrams and waveforms were recorded after 10-min equilibration at each dose in the conscious ANS-intact or ANS-blocked state. Levosimendan increased heart rate (HR), CO, mean and diastolic CBF velocity, and pressure-work index (PWI, an estimate of myocardial oxygen consumption) and decreased LV end-diastolic pressure (EDP), systemic vascular resistance (SVR), end-systolic and end-diastolic segment length, and mean and diastolic coronary vascular resistance (CVR) in dogs with intact ANS function. Levosimendan-induced increases in HR and PWI and decreases in SVR were attenuated by ANS blockade. Levosimendan caused equivalent dose-dependent increases in Mw in ANS-intact and ANS-blocked dogs, consistent with a positive inotropic effect independent of ANS activity. Levosimendan decreased tau (e.g., 35 +/- 1 ms during

  12. Longitudinal hemodynamic measurements in swine heart failure using a fully implantable telemetry system.

    PubMed

    Choy, Jenny S; Zhang, Zhen-Du; Pitsillides, Koullis; Sosa, Margo; Kassab, Ghassan S

    2014-01-01

    Chronic monitoring of heart rate, blood pressure, and flow in conscious free-roaming large animals can offer considerable opportunity to understand the progression of cardiovascular diseases and can test new diagnostics and therapeutics. The objective of this study was to demonstrate the feasibility of chronic, simultaneous measurement of several hemodynamic parameters (left ventricular pressure, systemic pressure, blood flow velocity, and heart rate) using a totally implantable multichannel telemetry system in swine heart failure models. Two solid-state blood pressure sensors were inserted in the left ventricle and the descending aorta for pressure measurements. Two Doppler probes were placed around the left anterior descending (LAD) and the brachiocephalic arteries for blood flow velocity measurements. Electrocardiographic (ECG) electrodes were attached to the surface of the left ventricle to monitor heart rate. The telemeter body was implanted in the right side of the abdomen under the skin for approximately 4 to 6 weeks. The animals were subjected to various heart failure models, including volume overload (A-V fistula, n = 3), pressure overload (aortic banding, n = 2) and dilated cardiomyopathy (pacing-induced tachycardia, n = 3). Longitudinal changes in hemodynamics were monitored during the progression of the disease. In the pacing-induced tachycardia animals, the systemic blood pressure progressively decreased within the first 2 weeks and returned to baseline levels thereafter. In the aortic banding animals, the pressure progressively increased during the development of the disease. The pressure in the A-V fistula animals only showed a small increase during the first week and remained stable thereafter. The results demonstrated the ability of this telemetry system of long-term, simultaneous monitoring of blood flow, pressure and heart rate in heart failure models, which may offer significant utility for understanding cardiovascular disease progression and

  13. Longitudinal Hemodynamic Measurements in Swine Heart Failure Using a Fully Implantable Telemetry System

    PubMed Central

    Choy, Jenny S.; Zhang, Zhen-Du; Pitsillides, Koullis; Sosa, Margo; Kassab, Ghassan S.

    2014-01-01

    Chronic monitoring of heart rate, blood pressure, and flow in conscious free-roaming large animals can offer considerable opportunity to understand the progression of cardiovascular diseases and can test new diagnostics and therapeutics. The objective of this study was to demonstrate the feasibility of chronic, simultaneous measurement of several hemodynamic parameters (left ventricular pressure, systemic pressure, blood flow velocity, and heart rate) using a totally implantable multichannel telemetry system in swine heart failure models. Two solid-state blood pressure sensors were inserted in the left ventricle and the descending aorta for pressure measurements. Two Doppler probes were placed around the left anterior descending (LAD) and the brachiocephalic arteries for blood flow velocity measurements. Electrocardiographic (ECG) electrodes were attached to the surface of the left ventricle to monitor heart rate. The telemeter body was implanted in the right side of the abdomen under the skin for approximately 4 to 6 weeks. The animals were subjected to various heart failure models, including volume overload (A-V fistula, n = 3), pressure overload (aortic banding, n = 2) and dilated cardiomyopathy (pacing-induced tachycardia, n = 3). Longitudinal changes in hemodynamics were monitored during the progression of the disease. In the pacing-induced tachycardia animals, the systemic blood pressure progressively decreased within the first 2 weeks and returned to baseline levels thereafter. In the aortic banding animals, the pressure progressively increased during the development of the disease. The pressure in the A-V fistula animals only showed a small increase during the first week and remained stable thereafter. The results demonstrated the ability of this telemetry system of long-term, simultaneous monitoring of blood flow, pressure and heart rate in heart failure models, which may offer significant utility for understanding cardiovascular disease

  14. [Intracranial, cerebral perfusion pressure and systemic hemodynamic parameters during anesthesia induction in patients with traumatic brain compression].

    PubMed

    2012-01-01

    The study reports the dynamic of ICP, CPP and systemic hemodynamic rates during midazolam induction of anesthesia in patients with traumatic brain compression. Patients who need urgent surgery to eliminate brain compression of various degrees generally have intracranial hypertension. Midazolam administration decreases ICP by 22% from baseline under condition of stable hemodynamic and CPP. Depolarizing neuromuscular blocking agents' administration, mechanical ventilation and tracheal intubation lead to ICP elevation and CPP decreasing. The combination of midazolam and fentanil provides more reliable protection from hypertensive reactions.

  15. Hemodynamic actions of systemically injected pituitary adenylate cyclase activating polypeptide-27 in the rat

    NASA Technical Reports Server (NTRS)

    Whalen, E. J.; Johnson, A. K.; Lewis, S. J.

    1999-01-01

    The aims of this study were (1) to characterize the hemodynamic mechanisms underlying the hypotensive effects of pituitary adenylate cyclase activating polypeptide-27 (PACAP-27 0.1-2.0 nmol/kg, i.v.) in pentobarbital-anesthetized rats, and (2) to determine the roles of the autonomic nervous system, adrenal catecholamines and endothelium-derived nitric oxide (NO) in the expression of PACAP-27-mediated effects on hemodynamic function. PACAP-27 produced dose-dependent decreases in mean arterial blood pressure and hindquarter and mesenteric vascular resistances in saline-treated rats. PACAP-27 also produced pronounced falls in mean arterial blood pressure in rats treated with the ganglion blocker, chlorisondamine (5 mg/kg, i.v.). The hypotensive and vasodilator actions of PACAP-27 were not attenuated by the beta-adrenoceptor antagonist, propranolol (1 mg/kg, i.v.), or the NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME 50 micromol/kg, i.v.). PACAP-27 produced dose-dependent increases in heart rate whereas the hypotensive response produced by the nitrovasodilator, sodium nitroprusside (10 microg/kg, i.v.), was associated with a minimal tachycardia. The PACAP-27-induced tachycardia was unaffected by chlorisondamine, but was virtually abolished by propranolol. These results suggest that the vasodilator effects of PACAP-27 are due to actions in the microcirculation rather than to the release of adrenal catecholamines and that this vasodilation may not involve the release of endothelium-derived NO. These results also suggest that PACAP-27 produces tachycardia by directly releasing norepinephrine from cardiac sympathetic nerve terminals rather than by direct or baroreceptor reflex-mediated increases in sympathetic nerve activity.

  16. Hybrid System for Ex Vivo Hemorheological and Hemodynamic Analysis: A Feasibility Study.

    PubMed

    Yeom, Eunseop; Jun Kang, Yang; Lee, Sang Joon

    2015-06-19

    Precise measurement of biophysical properties is important to understand the relation between these properties and the outbreak of cardiovascular diseases (CVDs). However, a systematic measurement for these biophysical parameters under in vivo conditions is nearly impossible because of complex vessel shape and limited practicality. In vitro measurements can provide more biophysical information, but in vitro exposure changes hemorheological properties. In this study, a hybrid system composed of an ultrasound system and microfluidic device is proposed for monitoring hemorheological and hemodynamic properties under more reasonable experimental conditions. Biophysical properties including RBC aggregation, viscosity, velocity, and pressure of blood flows are simultaneously measured under various conditions to demonstrate the feasibility and performance of this measurement system. The proposed technique is applied to a rat extracorporeal loop which connects the aorta and jugular vein directly. As a result, the proposed system is found to measure biophysical parameters reasonably without blood collection from the rat and provided more detailed information. This hybrid system, combining ultrasound imaging and microfluidic techniques to ex vivo animal models, would be useful for monitoring the variations of biophysical properties induced by chemical agents. It can be used to understand the relation between biophysical parameters and CVDs.

  17. Hybrid System for Ex Vivo Hemorheological and Hemodynamic Analysis: A Feasibility Study

    PubMed Central

    Yeom, Eunseop; Jun Kang, Yang; Joon Lee, Sang

    2015-01-01

    Precise measurement of biophysical properties is important to understand the relation between these properties and the outbreak of cardiovascular diseases (CVDs). However, a systematic measurement for these biophysical parameters under in vivo conditions is nearly impossible because of complex vessel shape and limited practicality. In vitro measurements can provide more biophysical information, but in vitro exposure changes hemorheological properties. In this study, a hybrid system composed of an ultrasound system and microfluidic device is proposed for monitoring hemorheological and hemodynamic properties under more reasonable experimental conditions. Biophysical properties including RBC aggregation, viscosity, velocity, and pressure of blood flows are simultaneously measured under various conditions to demonstrate the feasibility and performance of this measurement system. The proposed technique is applied to a rat extracorporeal loop which connects the aorta and jugular vein directly. As a result, the proposed system is found to measure biophysical parameters reasonably without blood collection from the rat and provided more detailed information. This hybrid system, combining ultrasound imaging and microfluidic techniques to ex vivo animal models, would be useful for monitoring the variations of biophysical properties induced by chemical agents. It can be used to understand the relation between biophysical parameters and CVDs. PMID:26090816

  18. Prediction of Hemodynamic Response to Epinephrine via Model-Based System Identification.

    PubMed

    Bighamian, Ramin; Soleymani, Sadaf; Reisner, Andrew T; Seri, Istvan; Hahn, Jin-Oh

    2016-01-01

    In this study, we present a system identification approach to the mathematical modeling of hemodynamic responses to vasopressor-inotrope agents. We developed a hybrid model called the latency-dose-response-cardiovascular (LDC) model that incorporated 1) a low-order lumped latency model to reproduce the delay associated with the transport of vasopressor-inotrope agent and the onset of physiological effect, 2) phenomenological dose-response models to dictate the steady-state inotropic, chronotropic, and vasoactive responses as a function of vasopressor-inotrope dose, and 3) a physiological cardiovascular model to translate the agent's actions into the ultimate response of blood pressure. We assessed the validity of the LDC model to fit vasopressor-inotrope dose-response data using data collected from five piglet subjects during variable epinephrine infusion rates. The results suggested that the LDC model was viable in modeling the subjects' dynamic responses: After tuning the model to each subject, the r (2) values for measured versus model-predicted mean arterial pressure were consistently higher than 0.73. The results also suggested that intersubject variability in the dose-response models, rather than the latency models, had significantly more impact on the model's predictive capability: Fixing the latency model to population-averaged parameter values resulted in r(2) values higher than 0.57 between measured versus model-predicted mean arterial pressure, while fixing the dose-response model to population-averaged parameter values yielded nonphysiological predictions of mean arterial pressure. We conclude that the dose-response relationship must be individualized, whereas a population-averaged latency-model may be acceptable with minimal loss of model fidelity.

  19. Interstitial lung disease increases mortality in systemic sclerosis patients with pulmonary arterial hypertension without affecting hemodynamics and exercise capacity.

    PubMed

    Michelfelder, M; Becker, M; Riedlinger, A; Siegert, E; Drömann, D; Yu, X; Petersen, F; Riemekasten, G

    2017-02-01

    Published data suggest that coexisting interstitial lung disease (ILD) has an impact on mortality in patients with systemic sclerosis (SSc) and pulmonary arterial hypertension (PAH), but there is scarce knowledge if this is reflected by hemodynamics, exercise capacity, autoantibody profile, or pulmonary function. In this partially retrospective study, 27 SSc-PAH patients were compared to 24 SSc-PAH patients with coexisting ILD respecting to survival, pulmonary function, hemodynamics, exercise capacity, and laboratory parameters. Survival was significantly worse in SSc-PAH-ILD patients than in SSc patients with isolated PAH (1, 5, and 10-year survival rates 86, 54, and 54% versus 96, 92, and 82%, p = 0.013). Compared to isolated SSc-PAH patients, patients with SSc-PAH-ILD revealed lower forced expiratory volume after 1 s (FEV1) values at the time of PAH diagnosis as well as 1 and 2 years later (p = 0.002) without significant decrease in the PAH course in both groups. At PAH diagnosis, diffusion capacity for carbon monoxide (DLCO) values were lower in the ILD-PAH group. Coexisting ILD was not associated with lower exercise capacity, different FEV1/forced vital capacity (FVC) ratio, higher WHO functional class, or reduced hemodynamics. Higher levels of antibodies against angiotensin and endothelin receptors predict mortality in all SSc-PAH patients but could not differentiate between PAH patients with and without ILD. Our study confirmed an impact of ILD on mortality in SSc-PAH patients. Pulmonary function parameters can be used to distinguish PAH from PAH-ILD. The higher mortality rate cannot be explained by differences in hemodynamics, exercise capacity, or autoantibody levels. Mechanisms of mortality remain to be studied.

  20. [Invasive and minimally invasive hemodynamic monitoring].

    PubMed

    Hansen, Matthias

    2016-10-01

    Advanced hemodynamic monitoring is necessary for adequate management of high-risk patients or patients with derangement of circulation. Studies demonstrate a benefit of early goal directed therapy in unstable cardiopulmonary situations. In these days we have different possibilities of minimally invasive or invasive hemodynamic monitoring. Minimally invasive measurements like pulse conture analysis or pulse wave analysis being less accurate under some circumstances, however only an artery catheter is needed for cardiac output monitoring. Pulmonary artery, transpulmonary thermodilution and lithium dilution technology have acceptable accuracy in cardiac output measurement. For therapy of unstable circulation there are additionally parameters to obtain. The pulmonary artery catheter is the device with the largest rate of complications, used by a trained crew and with a correct indication, his use is unchained justified.

  1. Immunological Derangement in Hypocellular Myelodysplastic Syndromes

    PubMed Central

    Serio, B; Risitano, AM; Giudice, V; Montuori, N; Selleri, C

    2014-01-01

    Hypocellular or hypoplastic myelodysplastic syndromes (HMDS) are a distinct subgroup accounting for 10–15% of all MDS patients, that are characterized by the presence of bone marrow (BM) hypocellularity, various degree of dysmyelopoiesis and sometimes abnormal karyotype. Laboratory and clinical evidence suggest that HMDS share several immune-mediated pathogenic mechanisms with acquired idiopathic aplastic anemia (AA). Different immune-mediated mechanisms have been documented in the damage of marrow hematopoietic progenitors occurring in HMDS; they include oligoclonal expansion of cytotoxic T lymphocytes (CTLs), polyclonal expansion of various subtypes of T helper lymphocytes, overexpression of FAS-L and of the TNF–related apoptosis-inducing ligand (TRAIL), underexpression of Flice-like inhibitory protein long isoform (FLIPL) in marrow cells as well as higher release of Th1 cytokines, such as interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α). It has also been documented that some HMDS patients have higher frequency of polymorphisms linked both to high production of proinflammatory cytokines such as TNF-α and transforming growth factor-β and to the inhibition of T-cell mediated immune responses such as interleukin-10, further suggesting that immune-mediated mechanisms similar to those seen in AA patients may also operate in HMDS. Clinically, the strongest evidence for immune–mediated hematopoietic suppression in some HMDS is the response to immunosuppression including mainly cyclosporine, anti-thymocyte globulin and/or cyclosporine, or alemtuzumab. Here we review all these immune mechanisms as well as the influence of this deranged cellular and humoral immunologic mileau on the initiation and possible progression of MDS. All these observations are pivotal not only for a better understanding of MDS pathophysiology, but also for their immediate clinical implications, eventually leading to the identification of MDS patients who may benefit from

  2. Hemodynamic changes in cortical sensorimotor systems following hand and orofacial motor tasks and pulsed pneumotactile stimulation.

    PubMed

    Rosner, Austin O; Barlow, Steven M

    We performed a functional near-infrared spectroscopy (fNIRS) study of the evoked hemodynamic responses seen in hand and face sensorimotor cortical representations during (1) active motor tasks and (2) pulsed pneumotactile stimulation. Contralateral fNIRS measurements were performed on 22 healthy adult participants using a block paradigm that consisted of repetitive right hand and right oral angle somatosensory stimulation using a pulsed pneumotactile array stimulator, and repetitive right-hand grip compression and bilabial compressions on strain gages. Results revealed significant oxyhemoglobin (HbO) modulation across stimulus conditions in corresponding somatotopic cortical regions. Of the 22 participants, 86% exhibited a decreased HbO response during at least one of the stimulus conditions, which may be indicative of cortical steal, or hypo-oxygenation occurring in channels adjacent to the primary areas of activation. Across all conditions, 56% of participants' HbO responses were positive and 44% were negative. Hemodynamic responses most likely differed across hand and face motor and somatosensory cortical regions due to differences in regional arterial/venous anatomy, cortical vascular beds, extent and orientation of somatotopy, task dynamics, and mechanoreceptor typing in hand and face. The combination of optical imaging and task conditions allowed for non-invasive examination of hemodynamic changes in somatosensory and motor cortices using natural, pneumatic stimulation of glabrous hand and hairy skin of the lower face and functionally relevant and measurable motor tasks involving the same structures.

  3. Deep Phenotyping of Systemic Arterial Hemodynamics in HFpEF (Part 1): Physiologic and Technical Considerations.

    PubMed

    Chirinos, Julio A

    2017-02-16

    A better understanding of the pathophysiology of heart failure with a preserved left ventricular ejection fraction (HFpEF) is important. Detailed phenotyping of pulsatile hemodynamics has provided important insights into the pathophysiology of left ventricular remodeling and fibrosis, diastolic dysfunction, microvascular disease, and impaired oxygen delivery to peripheral skeletal muscle, all of which contribute to exercise intolerance, the cardinal feature of HFpEF. Furthermore, arterial pulsatile hemodynamic mechanisms likely contribute to the frequent presence of comorbidities, such as renal failure and dementia, in this population. Our therapeutic approach to HFpEF can be enhanced by clinical phenotyping tools with the potential to "segment" this population into relevant pathophysiologic categories or to identify individuals exhibiting prominent specific abnormalities that can be targeted by pharmacologic interventions. This review describes relevant technical and physiologic aspects regarding the deep phenotyping of arterial hemodynamics in HFpEF. In an accompanying review, the potential of this approach to enhance our clinical and therapeutic approach to HFpEF is discussed.

  4. Corrected near infrared spectroscopy, C-NIRS: An optical system for extracting hemodynamic signatures unique to the brain

    NASA Astrophysics Data System (ADS)

    Saager, Rolf B.

    We propose a method, dubbed Corrected Near Infrared Spectroscopy (C-NIRS), to isolate absorption trends confined to the lower layer of a two-layer turbid medium, as is desired in near-infrared spectroscopy (NIRS) of cerebral hemodynamics. The theory behind the operation of this method has been developed and discussed. Several two-layer Monte-Carlo simulations of NIRS time series were generated using a physiologically relevant range of optical properties. Initial results show that by measuring absorption trends at two source-detector separations and performing a least-squares fit of one to the other, processed signals strongly resemble the simulated absorption properties unique to the bottom-layer. Through this approach, it has been demonstrated that fitting coefficients can be estimated without any a priori knowledge of the optical properties present in the model. An analytical approximation for the least squares coefficient provides physical insight into the nature of errors and suggests ways to reduce them. Next, a multi-detector, continuous wave, near infrared spectroscopy system has been developed to examine whether the hemodynamics of the scalp and brain in adults contain significant layer-like hemodynamic trends. NIRS measurements were made using contrasting geometries, one with four detectors equidistant from a source 33 mm away, and one with detectors collinear with the source (5-33 mm away). When NIRS time series were acquired over the prefrontal cortex from resting adults using both geometries, variations among the time series were consistent with a substantially homogeneous two-layer model ( p < 0.001) and inconsistent with one dominated by heterogeneities. Additionally, when time series measured 5 mm from the source were subtracted from corresponding 33 mm signals via a least-squares algorithm, 60% of the hemoglobin changes were on average removed. These results suggest that hemodynamic trends present in the scalp can contribute significantly to NIRS

  5. Flexibly combined optical microangiography and dual-wavelength laser speckle system for comprehensive imaging of hemodynamic and metabolic responses

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Qin, Jia; An, Lin; Wang, Ruikang K.

    2014-03-01

    We have proposed and developed a multi-modal non-invasive biomedical optical imager. It was combined from the subsystems of optical microangiography and dual-wavelength laser speckle contrast imaging. The system was designed to maintain the performances of both subsystems. It was capable of simultaneously imaging the hemodynamic and metabolic responses in tissue environment in vivo. To achieve such requirements, we utilized unique optical setup, such as paired dichroic mirrors to compensate dispersion, additional relay lens to increase working distance and translational sample probe to freely select imaging area and focal plane. The multi-functionality of the system was demonstrated in an investigation of hemodynamic and metabolic responses on an acute wound healing model in mouse pinna in vivo. The microvasculature, blood flow and hemoglobin concentration from millimeter down to capillary level were comprehensively visualized. The captured instantaneous responses to wound onset differed greatly between localized areas; after that blood flow had a rebalance tendency, and hemoglobin concentration dynamically recovered to baseline situation.

  6. Hemodynamic signature of breast cancer under fractional mammographic compression using a dynamic diffuse optical tomography system

    PubMed Central

    Carp, Stefan A.; Sajjadi, Amir Y.; Wanyo, Christy M.; Fang, Qianqian; Specht, Michelle C.; Schapira, Lidia; Moy, Beverly; Bardia, Aditya; Boas, David A.; Isakoff, Steven J.

    2013-01-01

    Near infrared dynamic diffuse optical tomography measurements of breast hemodynamics during fractional mammographic compression offer a novel contrast mechanism for detecting breast cancer and monitoring chemotherapy. Tissue viscoelastic relaxation during the compression period leads to a slow reduction in the compression force and reveals biomechanical and metabolic differences between healthy and lesion tissue. We measured both the absolute values and the temporal evolution of hemoglobin concentration during 25-35 N of compression for 22 stage II and III breast cancer patients scheduled to undergo neoadjuvant chemotherapy. 17 patients were included in the group analysis (average tumor size 3.2 cm, range: 1.3-5.7 cm). We observed a statistically significant differential decrease in total and oxy-hemoglobin, as well as in hemoglobin oxygen saturation in tumor areas vs. healthy tissue, as early as 30 seconds into the compression period. The hemodynamic contrast is likely driven by the higher tumor stiffness and different viscoelastic relaxation rate, as well as the higher tumor oxygen metabolism rate. PMID:24409390

  7. Hands-On Particle Image Velocimetry Experience for Bioengineering Students Using the Interactive Flowcoach System to Understand Aneurysm Hemodynamics

    NASA Astrophysics Data System (ADS)

    Roszelle, Breigh N.; Okcay, Murat; Oztekin, B. Uygar; Frakes, David H.

    2012-11-01

    The Flowcoach system is a flow visualization and analysis platform from Interactive Flow Studies that uses particle image velocimetry (PIV) and computational fluid dynamics to provide interactive fluid dynamics education. In the spring of 2012, Flowcoach was used at Arizona State University to help teach bioengineering students about biofluid mechanics. A custom insert was made for Flowcoach to model an anatomical aneurysm that could be treated with a high-porosity flow diverting stent. Students performed PIV on the treated aneurysm model in small lab groups using Flowcoach and then wrote reports comparing their results to those from an untreated aneurysm model. The students were surveyed before and after the project and asked to rate their understanding of general biofluid mechanics, as well as experimental fluid mechanics and aneurysmal hemodynamics. Of the 76 students surveyed, 86% indicated an increase in their understanding of biofluid mechanics, and 90% indicated an increase in their understanding of both PIV and cerebral aneurysm hemodynamics. Students' written feedback showed that they felt Flowcoach and the interactive learning experience it provided were both interesting and beneficial to their future careers as engineers.

  8. Effect of postural stimulation on systemic hemodynamics and sympathetic nervous activity in systemic hypertension.

    PubMed

    Izzo, J L; Sander, E; Larrabee, P S

    1990-02-01

    The contributions of the carotid sinus and cardiopulmonary baroreflexes to the interindividual variation in sympathetic nervous system activation caused by postural adaptation were indirectly assessed in 68 mild hypertensive subjects. Supine and upright plasma norepinephrine (NE), blood pressure (cuff) and cardiac output (acetylene rebreathing) were measured. Mean arterial pressure (MAP), carotid sinus pressure, stroke volume and systemic vascular resistance were calculated. Stroke volume was assumed to be proportional to the degree of stretch of cardiac mechanoreceptors, carotid sinus MAP was assumed to be proportional to carotid sinus stretch and plasma NE to reflect sympathetic nervous activity. Plasma NE correlated inversely with stroke volume (r = -0.62, p less than 10(-14] and estimated carotid sinus MAP (r = -0.33, p less than 0.0002) and positively with systemic vascular resistance (r = 0.59, p less than 10(-10]. Holding systemic vascular resistance constant by partial regression, the inverse relation between plasma NE and stroke volume remained (partial r = -0.36, p less than 0.02). Multiple linear regression yielded the equation: plasma NE (pg/ml) = 720 + 4.3 age - 5.1 stroke volume (ml) - 1.0 carotid sinus MAP (mm Hg). Substituting mean supine and upright values for stroke volume and carotid sinus MAP in this equation, it can be roughly estimated that changes in stroke volume account for as much as 60% of the postural variation in plasma NE in hypertensives, whereas only 15% of this variation is caused by changes in carotid sinus pressure. These findings suggest that cardiopulmonary baroreflexes are primary activators of the sympathetic nervous system during postural adaptation.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Metabolic Derangements in Lichen Planus - A Case Control Study

    PubMed Central

    Kar, Bikash Ranjan; Panda, Maitreyee

    2016-01-01

    Introduction An association between psoriasis and metabolic syndrome has been established in previous studies. Lichen Planus (LP) is also a chronic inflammatory disease morphologically related to psoriasis and few studies have shown association of metabolic derangements in LP. Aim To study the association of metabolic derangements in LP. Materials and Methods A prospective case control study was undertaken for a period of one year. Age and sex matched patients of LP and other non-inflammatory diseases were taken as cases and controls respectively. Data on height, weight, lipid profile and fasting blood glucose levels were collected for all the patients. Body Mass Index (BMI) was calculated. Results A total of 80 patients were recruited, 40 cases and 40 controls. The mean values for all the lipid and glucose parameters were high in cases as compared to controls with significant p-values. Conclusion In the present study metabolic derangements were seen in patients with LP. PMID:28050485

  10. S3 guidelines for intensive care in cardiac surgery patients: hemodynamic monitoring and cardiocirculary system.

    PubMed

    Carl, M; Alms, A; Braun, J; Dongas, A; Erb, J; Goetz, A; Goepfert, M; Gogarten, W; Grosse, J; Heller, A R; Heringlake, M; Kastrup, M; Kroener, A; Loer, S A; Marggraf, G; Markewitz, A; Reuter, D; Schmitt, D V; Schirmer, U; Wiesenack, C; Zwissler, B; Spies, C

    2010-06-15

    Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery (Deutsche Gesellschaft für Thorax-, Herz- und Gefässchirurgie, DGTHG) and the German Society for Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und lntensivmedizin, DGAI) made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess the available monitoring methods with regard to indication, procedures, predication, limits, contraindications and risks for use. The differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilatators, inodilatators and calcium sensitizers and the use of intra-aortic balloon pumps will also be addressed. The guideline has been developed following the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical

  11. S3 guidelines for intensive care in cardiac surgery patients: hemodynamic monitoring and cardiocirculary system

    PubMed Central

    Carl, M.; Alms, A.; Braun, J.; Dongas, A.; Erb, J.; Goetz, A.; Goepfert, M.; Gogarten, W.; Grosse, J.; Heller, A. R.; Heringlake, M.; Kastrup, M.; Kroener, A.; Loer, S. A.; Marggraf, G.; Markewitz, A.; Reuter, D.; Schmitt, D. V.; Schirmer, U.; Wiesenack, C.; Zwissler, B.; Spies, C.

    2010-01-01

    Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery (Deutsche Gesellschaft für Thorax-, Herz- und Gefäßchirurgie, DGTHG) and the German Society for Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und lntensivmedizin, DGAI) made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess the available monitoring methods with regard to indication, procedures, predication, limits, contraindications and risks for use. The differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilatators, inodilatators and calcium sensitizers and the use of intra-aortic balloon pumps will also be addressed. The guideline has been developed following the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical

  12. Simulation of hemodynamic responses to the valsalva maneuver: an integrative computational model of the cardiovascular system and the autonomic nervous system.

    PubMed

    Liang, Fuyou; Liu, Hao

    2006-02-01

    The Valsalva maneuver is a frequently used physiological test in evaluating the cardiovascular autonomic functions in human. Although a large pool of experimental data has provided substantial insights into different aspects of the mechanisms underlying the cardiovascular regulations during the Valsalva maneuver, so far a complete comprehension of these mechanisms and the interactions among them is unavailable. In the present study, a computational model of the cardiovascular system (CVS) and its interaction with the autonomic nervous system (ANS) was developed for the purpose of quantifying the individual roles of the CVS and the ANS in the hemodynamic regulations during the Valsalva maneuver. A detailed computational compartmental parameter model of the global CVS, a system of mathematical equations representing the autonomic nervous reflex regulatory functions, and an empirical cerebral autoregulation (CA) model formed the main body of the present model. Based on simulations of the Valsalva maneuvers at several typical postures, it was demonstrated that hemodynamic responses to the maneuver were not only determined by the ANS-mediated cardiovascular regulations, but also significantly affected by the postural-change-induced hemodynamic alterations preceding the maneuver. Moreover, the large-magnitude overshoot in cerebral perfusion immediately after the Valsalva maneuver was found to result from a combined effect of the circulatory autonomic functions, the CA, and the cerebral venous blood pressure.

  13. Combined drug therapy in porcine endotoxemia. Hemodynamic and proteolytic effects of antagonists against histamine, serotonin and endorphin.

    PubMed

    Naess, F; Roeise, O; Stadaas, J O; Aasen, A O

    1990-01-01

    In order to investigate the importance of potential mediators of pathophysiologic derangements in endotoxemia, we have examined the effects of the combined administration of antagonists against histamine, serotonin and endorphins in a porcine model of endotoxemia. The treatment regimen significantly reduced the increase in pulmonary artery pressure, pulmonary vascular resistance and systemic arterial pressure seen in the early stages of endotoxemia. Also, cardiac output was better maintained. However, the hemodynamic performance after an observation period of 5 h was not statistically different from untreated animals. The treatment regimen did not hinder the activation of the kallikreinkinin and fibrinolytic systems of plasma, which was evident in both treated and untreated animals, and could not counteract the increase in hematocrit or leukopenia seen in this model. This study shows that the combined blocking of histamine, serotonin and endorphines is not enough to abrogate the detrimental effects of endotoxin in a porcine model.

  14. A Mock Circulatory System Incorporating a Compliant 3D-Printed Anatomical Model to Investigate Pulmonary Hemodynamics.

    PubMed

    Knoops, Paul G M; Biglino, Giovanni; Hughes, Alun D; Parker, Kim H; Xu, Linzhang; Schievano, Silvia; Torii, Ryo

    2016-12-07

    A realistic mock circulatory system (MCS) could be a valuable in vitro testbed to study human circulatory hemodynamics. The objective of this study was to design a MCS replicating the pulmonary arterial circulation, incorporating an anatomically representative arterial model suitable for testing clinically relevant scenarios. A second objective of the study was to ensure the system's compatibility with magnetic resonance imaging (MRI) for additional measurements. A latex pulmonary arterial model with two generations of bifurcations was manufactured starting from a 3D-printed mold reconstructed from patient data. The model was incorporated into a MCS for in vitro hydrodynamic measurements. The setup was tested under physiological pulsatile flow conditions and results were evaluated using wave intensity analysis (WIA) to investigate waves traveling in the arterial system. Increased pulmonary vascular resistance (IPVR) was simulated as an example of one pathological scenario. Flow split between right and left pulmonary artery was found to be realistic (54 and 46%, respectively). No substantial difference in pressure waveform was observed throughout the various generations of bifurcations. Based on WIA, three main waves were identified in the main pulmonary artery (MPA), that is, forward compression wave, backward compression wave, and forward expansion wave. For IPVR, a rise in mean pressure was recorded in the MPA, within the clinical range of pulmonary arterial hypertension. The feasibility of using the MCS in the MRI scanner was demonstrated with the MCS running 2 h consecutively while acquiring preliminary MRI data. This study shows the development and verification of a pulmonary MCS, including an anatomically correct, compliant latex phantom. The setup can be useful to explore a wide range of hemodynamic questions, including the development of patient- and pathology-specific models, considering the ease and low cost of producing rapid prototyping molds, and the

  15. The hemodynamic effect of the support mode for the intra-aorta pump on the cardiovascular system.

    PubMed

    Gao, Bin; Chang, Yu; Xuan, Yanjiao; Zeng, Yi; Liu, Youjun

    2013-02-01

    Intra-aorta pump is a novel rotary ventricular assist device. Because of the special structure and connection with the native heart, the hemodynamic effect of support mode of this pump on the cardiovascular system is not clear. In this work, three support modes, including "constant speed" mode, "co-pulse" mode, and "counter-pulse" mode, have been designed for the intra-aorta pump to evaluate the hemodynamic effect of different support modes on the cardiovascular system. Simulation results demonstrate that that both "co-pulse" mode and "counter-pulse" mode can achieve better unloading performance than "constant speed" mode. The intra-aorta pump controlled by "co-pulse" mode is beneficial for improving coronary flow. Moreover, the external work, which is defined as the product of left ventricular pressure and cardiac output, under "co-pulse" mode is the minimum of the three support modes (0.783 w vs. 0.615 w vs. 0.702 w). The pulsatility ratio, defined as the ratio of the peak-to-peak value of arterial pressure (AP) to the mean arterial pressure value, under "co-pulse" mode is the maximum of the three modes (24% vs. 32.8% vs. 23.7%). The equivalent afterload value, which is the ratio of pulsatile pressure at the pump inflow and pulsatile pump flow, is larger than other support modes (0.596 mm Hg.s/mL vs. 0.9704 mm Hg.s/mL vs. 0.55 mm Hg.s/mL). In brief, the intra-aorta pump under "co-pulse" mode support is beneficial for improving myocardial perfusion and restoring pulsatility of AP, while "counter-pulse" mode is beneficial to the perfusion of vital organs.

  16. Cerebral Hemodynamic Responses During Dynamic Posturography: Analysis with a Multichannel Near-Infrared Spectroscopy System

    PubMed Central

    Takakura, Hiromasa; Nishijo, Hisao; Ishikawa, Akihiro; Shojaku, Hideo

    2015-01-01

    To investigate cortical roles in standing balance, cortical hemodynamic activity was recorded from the right hemisphere using near-infrared spectroscopy (NIRS) while subjects underwent the sensory organization test (SOT) protocol that systematically disrupts sensory integration processes (i.e., somatosensory or visual inputs or both). Eleven healthy men underwent the SOT during NIRS recording. Group statistical analyses were performed based on changes in oxygenated hemoglobin concentration in 10 different cortical regions of interest and on a general linear analysis with NIRS statistical parametric mapping. The statistical analyses indicated significant activation in the right frontal operculum (f-Op), right parietal operculum (p-Op), and right superior temporal gyrus (STG), right posterior parietal cortex (PPC), right dorsal and ventral premotor cortex (PMC), and the supplementary motor area (SMA) under various conditions. The activation patterns in response to specific combinations of SOT conditions suggested that (1) f-Op, p-Op, and STG are essential for sensory integration when standing balance is perturbed; (2) the SMA is involved in the execution of volitional action and establishment of new motor programs to maintain postural balance; and (3) the PPC and PMC are involved in the updating and computation of spatial reference frames during instances of sensory conflict between vestibular and visual information. PMID:26635574

  17. Ventilatory, hemodynamic, sympathetic nervous system, and vascular reactivity changes after recurrent nocturnal sustained hypoxia in humans.

    PubMed

    Gilmartin, Geoffrey S; Tamisier, Renaud; Curley, Matthew; Weiss, J Woodrow

    2008-08-01

    Recurrent and intermittent nocturnal hypoxia is characteristic of several diseases including chronic obstructive pulmonary disease, congestive heart failure, obesity-hypoventilation syndrome, and obstructive sleep apnea. The contribution of hypoxia to cardiovascular morbidity and mortality in these disease states is unclear, however. To investigate the impact of recurrent nocturnal hypoxia on hemodynamics, sympathetic activity, and vascular tone we evaluated 10 normal volunteers before and after 14 nights of nocturnal sustained hypoxia (mean oxygen saturation 84.2%, 9 h/night). Over the exposure, subjects exhibited ventilatory acclimatization to hypoxia as evidenced by an increase in resting ventilation (arterial Pco(2) 41.8 +/- 1.5 vs. 37.5 +/- 1.3 mmHg, mean +/- SD; P < 0.05) and in the isocapnic hypoxic ventilatory response (slope 0.49 +/- 0.1 vs. 1.32 +/- 0.2 l/min per 1% fall in saturation; P < 0.05). Subjects exhibited a significant increase in mean arterial pressure (86.7 +/- 6.1 vs. 90.5 +/- 7.6 mmHg; P < 0.001), muscle sympathetic nerve activity (20.8 +/- 2.8 vs. 28.2 +/- 3.3 bursts/min; P < 0.01), and forearm vascular resistance (39.6 +/- 3.5 vs. 47.5 +/- 4.8 mmHg.ml(-1).100 g tissue.min; P < 0.05). Forearm blood flow during acute isocapnic hypoxia was increased after exposure but during selective brachial intra-arterial vascular infusion of the alpha-blocker phentolamine it was unchanged after exposure. Finally, there was a decrease in reactive hyperemia to 15 min of forearm ischemia after the hypoxic exposure. Recurrent nocturnal hypoxia thus increases sympathetic activity and alters peripheral vascular tone. These changes may contribute to the increased cardiovascular and cerebrovascular risk associated with clinical diseases that are associated with chronic recurrent hypoxia.

  18. Hemodynamic effects of dilevalol in patients with systemic hypertension and left ventricular dysfunction.

    PubMed

    Kinhal, V; Kulkarni, A; Pozderac, R; Cubbon, J

    1989-06-05

    Hemodynamic and left ventricular function parameters were measured in patients with mild to moderate hypertension and compromised left ventricular function who were given dilevalol, an antihypertensive agent with selective beta 2-agonism and nonselective beta-antagonist activity. After a 2- to 3-week placebo washout period, 9 patients were given dilevalol titrated upward from 100 to 600 mg twice daily over a 7-week period to achieve a supine diastolic blood pressure of less than 90 mm Hg with a decrease of greater than or equal to 10 mm Hg from baseline. Multigated radionuclide ventriculography and systolic and diastolic time intervals were performed after the pretreatment placebo washout, at the end of 2 weeks' maintenance dosing, and after a 7- to 10-day post-treatment discontinuation and placebo washout period. At an average daily dose of dilevalol, 444 mg, heart rate at rest decreased significantly (p less than 0.01) during treatment and increased during post-treatment placebo. Systolic and diastolic blood pressures at rest decreased significantly (p less than 0.01) during treatment and increased during post-treatment placebo. At maximal exercise, changes in blood pressure and heart rate were significantly blunted (p less than 0.05) during treatment. Ejection fraction at rest increased significantly (p less than 0.01) during treatment, with no significant change occurring during exercise, and decreased during post-treatment placebo. Preejection period decreased significantly during treatment (p less than 0.005) and increased during post-treatment placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Three dimensional transient multifield analysis of a piezoelectric micropump for drug delivery system for treatment of hemodynamic dysfunctions.

    PubMed

    Nisar, Asim; Afzulpurkar, Nitin; Tuantranont, Adisorn; Mahaisavariya, Banchong

    2008-12-01

    In this paper, we present design of a transdermal drug delivery system for treatment of cardiovascular or hemodynamic disorders such as hypertension. The system comprises of integrated control electronics and microelectromechanical system devices such as micropump, micro blood pressure sensor and microneedle array. The objective is to overcome the limitations of oral therapy such as variable absorption profile and the need for frequent dosing, by fabricating a safe, reliable and cost effective transdermal drug delivery system to dispense various pharmacological agents through the skin for treatment of hemodynamic dysfunction such as hypertension. Moreover, design optimization of a piezoelectrically actuated valveless micropump is presented for the drug delivery system. Because of the complexity in analysis of piezoelectric micropump, which involves structural and fluid field couplings in a complicated geometrical arrangement, finite element (FE) numerical simulation rather than an analytical system has been used. The behavior of the piezoelectric actuator with biocompatible polydimethylsiloxane membrane is first studied by conducting piezoelectric analysis. Then the performance of the valveless micropump is analyzed by building a three dimensional electric-solid-fluid model of the micropump. The effect of geometrical dimensions on micropump characteristics and efficiency of nozzle/diffuser elements of a valveless micropump is investigated in the transient analysis using multiple code coupling method. The deformation results of the membrane using multifield code coupling analysis are in good agreement with analytical as well as results of single code coupling analysis of a piezoelectric micropump. The analysis predicts that to enhance the performance of the micropump, diffuser geometrical dimensions such as diffuser length, diffuser neck width and diffuser angle need to be optimized. Micropump flow rate is not strongly affected at low excitation frequencies from 10

  20. Study of endothelial cell apoptosis using fluorescence resonance energy transfer (FRET) biosensor cell line with hemodynamic microfluidic chip system.

    PubMed

    Yu, J Q; Liu, X F; Chin, L K; Liu, A Q; Luo, K Q

    2013-07-21

    To better understand how hyperglycemia induces endothelial cell dysfunction under the diabetic conditions, a hemodynamic microfluidic chip system was developed. The system combines a caspase-3-based fluorescence resonance energy transfer (FRET) biosensor cell line which can detect endothelial cell apoptosis in real-time, post-treatment effect and with a limited cell sample, by using a microfluidic chip which can mimic the physiological pulsatile flow profile in the blood vessel. The caspase-3-based FRET biosensor endothelial cell line (HUVEC-C3) can produce a FRET-based sensor protein capable of probing caspase-3 activation. When the endothelial cells undergo apoptosis, the color of the sensor cells changes from green to blue, thus sensing apoptosis. A double-labeling fluorescent technique (yo pro-1 and propidium iodide) was used to validate the findings revealed by the FRET-based caspase sensor. The results show high rates of apoptosis and necrosis of endothelial cells when high glucose concentration was applied in our hemodynamic microfluidic chip combined with an exhaustive pulsatile flow profile. The two apoptosis detection techniques (fluorescent method and FRET biosensor) are comparable; but FRET biosensor offers more advantages such as real-time observation and a convenient operating process to generate more accurate and reliable data. Furthermore, the activation of the FRET biosensor also confirms the endothelial cell apoptosis induced by the abnormal pulsatile shear stress and high glucose concentration is through caspase-3 pathway. A 12% apoptotic rate (nearly a 4-fold increase compared to the static condition) was observed when the endothelial cells were exposed to a high glucose concentration of 20 mM under 2 h exhaustive pulsatile shear stress of 30 dyne cm(-2) and followed with another 10 h normal pulsatile shear stress of 15 dyne cm(-2). Therefore, the most important finding of this study is to develop a novel endothelial cell apoptosis detection

  1. Impact of Pulsatility and Flow Rates on Hemodynamic Energy Transmission in an Adult Extracorporeal Life Support System.

    PubMed

    Wolfe, Rachel; Strother, Ashton; Wang, Shigang; Kunselman, Allen R; Ündar, Akif

    2015-07-01

    This study investigated the total hemodynamic energy (THE) and surplus hemodynamic energy transmission (SHE) of a novel adult extracorporeal life support (ECLS) system with nonpulsatile and pulsatile settings and varying pulsatility to define the most effective setting for this circuit. The circuit consisted of an i-cor diagonal pump (Xenios AG, Heilbronn, Germany), an XLung membrane oxygenator (Xenios AG), an 18 Fr Medos femoral arterial cannula (Xenios AG), a 23/25 Fr Estech RAP femoral venous cannula (San Ramon, CA, USA), 3/8 in ID × 140 cm arterial tubing, and 3/8 in ID × 160 cm venous tubing. Priming was done with lactated Ringer's solution and packed red blood cells (HCT 36%). The trials were conducted at flow rates 1-4 L/min (1 L/min increments) under nonpulsatile and pulsatile mode, with differential speed values 1000-4000 rpm (1000 rpm increments) at 36°. The pseudo patient's mean arterial pressure was kept at 100 mm Hg using a Hoffman clamp during all trials. Real-time flow and pressure data were collected using a custom-based data acquisition system. Mean pressures across the circuit increased with increasing flow rates, but increased insignificantly with increasing differential speed values. Mean pressure did not change significantly between pulsatile and nonpulsatile modes. Pulsatile flow created more THE than nonpulsatile flow at the preoxygenator site (P < 0.01). Of the different components of the circuit, the arterial cannula created the greatest THE loss. THE loss across the circuit ranged from 24.8 to 71.3%. Still, under pulsatile mode, more THE was delivered to the pseudo patient at low flow rates. No SHE was created with nonpulsatile flow, but SHE was created with pulsatile flow, and increased with increasing differential speed values. At lower flow rates (1-2 L/min), the arterial cannula contributed the most to SHE loss, but at higher flow rates the arterial tubing created the most SHE loss. The circuit

  2. Design, fabrication and analysis of silicon hollow microneedles for transdermal drug delivery system for treatment of hemodynamic dysfunctions.

    PubMed

    Ashraf, M W; Tayyaba, S; Nisar, A; Afzulpurkar, N; Bodhale, D W; Lomas, T; Poyai, A; Tuantranont, A

    2010-09-01

    In this paper, we present design, fabrication and coupled multifield analysis of hollow out-of-plane silicon microneedles with piezoelectrically actuated microfluidic device for transdermal drug delivery (TDD) system for treatment of cardiovascular or hemodynamic disorders such as hypertension. The mask layout design and fabrication process of silicon microneedles and reservoir involving deep reactive ion etching (DRIE) is first presented. This is followed by actual fabrication of silicon hollow microneedles by a series of combined isotropic and anisotropic etching processes using inductively coupled plasma (ICP) etching technology. Then coupled multifield analysis of a MEMS based piezoelectrically actuated device with integrated silicon microneedles is presented. The coupledfield analysis of hollow silicon microneedle array integrated with piezoelectric micropump has involved structural and fluid field couplings in a sequential structural-fluid analysis on a three-dimensional model of the microfluidic device. The effect of voltage and frequency on silicon membrane deflection and flow rate through the microneedle is investigated in the coupled field analysis using multiple code coupling method. The results of the present study provide valuable benchmark and prediction data to fabricate optimized designs of the silicon hollow microneedle based microfluidic devices for transdermal drug delivery applications.

  3. [The effect of combined treatment with the use of magnetotherapy on the systemic hemodynamics of patients with ischemic heart disease and spinal osteochondrosis].

    PubMed

    Dudchenko, M A; Vesel'skiĭ, I Sh; Shtompel', V Iu

    1992-05-01

    The authors examined 66 patients with ischemic heart disease and concomitant cervico-thoracic osteochondrosis and 22 patients without osteochondrosis. Differences were revealed in values of the systemic hemodynamics with prevalence of the hypokinetic type in patients with combined pathology. Inclusion of magnetotherapy in the treatment complex of patients with ischemic heart disease and osteochondrosis favours clinical improvement, normalization of indices of central and regional blood circulation.

  4. Effects of Direct Renin Blockade on Renal & Systemic Hemodynamics and on RAAS Activity, in Weight Excess and Hypertension: A Randomized Clinical Trial

    PubMed Central

    Kwakernaak, A. J.; Roksnoer, L. C.; Lambers Heerspink, H. J.; van den Berg-Garrelds, I.; Lochorn, G. A.; van Embden Andres, J. H.; Klijn, M. A.; Kobori, H.; Danser, A. H. J.; Laverman, G. D.; Navis, G. J.

    2017-01-01

    Aim The combination of weight excess and hypertension significantly contributes to cardiovascular risk and progressive kidney damage. An unfavorable renal hemodynamic profile is thought to contribute to this increased risk and may be ameliorated by direct renin inhibition (DRI). The aim of this trial was to assess the effect of DRI on renal and systemic hemodynamics and on RAAS activity, in men with weight excess and hypertension. Methods A randomized, double-blind, cross-over clinical trial to determine the effect of DRI (aliskiren 300 mg/day), with angiotensin converting enzyme inhibition (ACEi; ramipril 10 mg/day) as a positive control, on renal and systemic hemodynamics, and on RAAS activity (n = 15). Results Mean (SEM) Glomerular filtration rate (101 (5) mL/min/1.73m2) remained unaffected by DRI or ACEi. Effective renal plasma flow (ERPF; 301 (14) mL/min/1.73m2) was increased in response to DRI (320 (14) mL/min/1.73m2, P = 0.012) and ACEi (317 (15) mL/min/1.73m2, P = 0.045). Filtration fraction (FF; 34 (0.8)%) was reduced by DRI only (32 (0.7)%, P = 0.044). Mean arterial pressure (109 (2) mmHg) was reduced by DRI (101 (2) mmHg, P = 0.008) and ACEi (103 (3) mmHg, P = 0.037). RAAS activity was reduced by DRI and ACEi. Albuminuria (20 [9–42] mg/d) was reduced by DRI only (12 [5–28] mg/d, P = 0.030). Conclusions In men with weight excess and hypertension, DRI and ACEi improved renal and systemic hemodynamics. Both DRI and ACEi reduced RAAS activity. Thus, DRI provides effective treatment in weight excess and hypertension. Trial Registration Dutch trial register, registration number: 2532 www.trialregister.nl PMID:28118402

  5. Synthetic cannabinoids: the multi-organ failure and metabolic derangements associated with getting high

    PubMed Central

    Sherpa, Dolkar; Paudel, Bishow M.; Subedi, Bishnu H.; Chow, Robert Dobbin

    2015-01-01

    Synthetic cannabinoids (SC), though not detected with routine urine toxicology screening, can cause severe metabolic derangements and widespread deleterious effects in multiple organ systems. The diversity of effects is related to the wide distribution of cannabinoid receptors in multiple organ systems. Both cannabinoid-receptor-mediated and non-receptor-mediated effects can result in severe cardiovascular, renal, and neurologic manifestations. We report the case of a 45-year-old African American male with ST-elevation myocardial infarction, subarachnoid hemorrhage, reversible cardiomyopathy, acute rhabdomyolysis, and severe metabolic derangement associated with the use of K2, an SC. Though each of these complications has been independently associated with SCs, the combination of these effects in a single patient has not been heretofore reported. This case demonstrates the range and severity of complications associated with the recreational use of SCs. Though now banned in the United States, use of systemic cannabinoids is still prevalent, especially among adolescents. Clinicians should be aware of their continued use and the potential for harm. To prevent delay in diagnosis, tests to screen for these substances should be made more readily available. PMID:26333853

  6. A hemodynamics model to study the collective behavior of the ventricular-arterial system

    NASA Astrophysics Data System (ADS)

    Lin Wang, Yuh-Ying; Wang, Wei-Kung

    2013-01-01

    Applying principles from complex systems to study the efficacy of integrative therapies has become a new interest in medical research. We aimed to construct a concise model for the ventricular-arterial (VA) system and to provide a systematic method for exploring its overall behavior. The transportation of blood from the heart to the peripheral arterioles via hydraulic pressure forces was described by a multi-rank model. Parts of the VA system that have strong mutual interactions were combined into a single sub system. Sub systems of four different ranks were characterized. We then applied the multi-rank model to analyze the aortic pressure wave generated by the periodic ventricular blood ejection, the renal pressure in response to the input from the VA system, and the blood flowing from the renal artery to its arterioles. Maintaining the pressure distribution along the main arteries and in all of the organs with the lowest possible ventricular input turned out to be the first principle for the operation of an efficient VA system. By this principle, we pointed out the benefit of some arterial structures in mammals, derived specific regulation rules and deduced some fundamental concepts for healing. The justification of the biomechanics in our model that differed greatly from those in the prevailing models was given. We concluded that the oscillatory motion and the pressure pulse of the arterial system can be analyzed as steady states with resonance behaviors and suggested utilizing this model to construct integrative therapies for diseases correlated with abnormality in blood circulation.

  7. Traumatic Brain Injury Creates Biphasic Systemic Hemodynamic and Organ Blood Flow Responses in Rats

    DTIC Science & Technology

    1990-01-01

    injury. Fluid percussion brain injury produced an immediate systemic hypertension followed by a hypotension and low cardiac output. Organ blood flows...37.5°C using a heating pad. The right femoral artery was cannulated for blood pressure monitoring using a quartz transducer (Hewlett Packard) and an...Since the hypertensive responses were usually maximal at 30 sec after injury, the mean arterial pressure and heart rate at 30 sec after sham injury

  8. Systemic arterial and venous determinants of renal hemodynamics in congestive heart failure.

    PubMed

    Braam, Branko; Cupples, William A; Joles, Jaap A; Gaillard, Carlo

    2012-03-01

    Heart and kidney interactions are fascinating, in the sense that failure of the one organ strongly affects the function of the other. In this review paper, we analyze how principal driving forces for glomerular filtration and renal blood flow are changed in heart failure. Moreover, renal autoregulation and modulation of neurohumoral factors, which can both have repercussions on renal function, are analyzed. Two paradigms seem to apply. One is that the renin-angiotensin system (RAS), the sympathetic nervous system (SNS), and extracellular volume control are the three main determinants of renal function in heart failure. The other is that the classical paradigm to analyze renal dysfunction that is widely applied in nephrology also applies to the pathophysiology of heart failure: pre-renal, intra-renal, and post-renal alterations together determine glomerular filtration. At variance with the classical paradigm is that the most important post-renal factor in heart failure seems renal venous hypertension that, by increasing renal tubular pressure, decreases GFR. When different pharmacological strategies to inhibit the RAS and SNS and to assist renal volume control are considered, there is a painful lack in knowledge about how widely applied drugs affect primary driving forces for ultrafiltration, renal autoregulation, and neurohumoral control. We call for more clinical physiological studies.

  9. Lubricin in synovial fluid of mild and severe temporomandibular joint internal derangements

    PubMed Central

    Perrotta, Rosario E.; Almeida, Luis-Eduardo; Loreto, Carla; Musumeci, Giuseppe

    2016-01-01

    Background To understand the molecular basis of temporomandibular joint (TMJ) pathologies, we aimed to investigate the lubricin levels in the TMJ synovial fluid (SF) of patients with mild to severe internal derangements (IDs). Material and Methods A total, 34 joints were the study group. Only patients, with a Wilkes stage of III, IV and V were included, in this sample. Control group consisted of SF from eight joints, from patients undergoing to orthognatic surgery. Concentrations of lubricin in the SF from both samples were measured using ELISA system. Results The mean lubricin concentration was 7.029 ± 0.21 µg/mL in stage III patients; 5.64 ± 0.10 µg/mL in stage IV patients, and 4.78 ± 0.11 µg/mL in stage V patients. The lubricin levels from stage IV and stage V patients differed significantly (P ≤ 0.001) from those of control subjects. Lubricin levels were inversely correlated with age and to VAS score. Conclusions The results of this cross-sectional study highlight the relationship between disease severity and the levels of lubricin in TMJ SF. Our findings suggest that novel biotherapeutic approaches, including the administration of recombinant lubricin in the joint cavity, for the treatment of TMJ diseases can be developed. Key words:Lubricin, TMJ, derangements, synovial fluid. PMID:27694778

  10. Invasive hemodynamics of constrictive pericarditis.

    PubMed

    Doshi, Shrenik; Ramakrishnan, Sivasubramanian; Gupta, Saurabh Kumar

    2015-01-01

    Cardiac catheterization and hemodynamic study is the gold standard for the diagnosis of pericardial constriction. Careful interpretation of the hemodynamic data is essential to differentiate it from other diseases with restrictive physiology. In this hemodynamic review we shall briefly discuss the physiologic basis of various hemodynamic changes seen in a patient with constrictive pericarditis.

  11. Effect of the Pulsatile Extracorporeal Membrane Oxygenation on Hemodynamic Energy and Systemic Microcirculation in a Piglet Model of Acute Cardiac Failure.

    PubMed

    Itoh, Hideshi; Ichiba, Shingo; Ujike, Yoshihito; Douguchi, Takuma; Obata, Hideaki; Inamori, Syuji; Iwasaki, Tatsuo; Kasahara, Shingo; Sano, Shunji; Ündar, Akif

    2016-01-01

    The objective of this study was to compare the effects of pulsatile and nonpulsatile extracorporeal membrane oxygenation (ECMO) on hemodynamic energy and systemic microcirculation in an acute cardiac failure model in piglets. Fourteen piglets with a mean body weight of 6.08 ± 0.86 kg were divided into pulsatile (N = 7) and nonpulsatile (N = 7) ECMO groups. The experimental ECMO circuit consisted of a centrifugal pump, a membrane oxygenator, and a pneumatic pulsatile flow generator system developed in-house. Nonpulsatile ECMO was initiated at a flow rate of 140 mL/kg/min for the first 30 min with normal heart beating, with rectal temperature maintained at 36°C. Ventricular fibrillation was then induced with a 3.5-V alternating current to generate a cardiac dysfunction model. Using this model, we collected the data on pulsatile and nonpulsatile groups. The piglets were weaned off ECMO at the end of the experiment (180 min after ECMO was initiated). The animals did not receive blood transfusions, inotropic drugs, or vasoactive drugs. Blood samples were collected to measure hemoglobin, methemoglobin, blood gases, electrolytes, and lactic acid levels. Hemodynamic energy was calculated using the Shepard's energy equivalent pressure. Near-infrared spectroscopy was used to monitor brain and kidney perfusion. The pulsatile ECMO group had a higher atrial pressure (systolic and mean), and significantly higher regional saturation at the brain level, than the nonpulsatile group (for both, P < 0.05). Additionally, the pulsatile ECMO group had higher methemoglobin levels within the normal range than the nonpulsatile group. Our study demonstrated that pulsatile ECMO produces significantly higher hemodynamic energy and improves systemic microcirculation, compared with nonpulsatile ECMO in acute cardiac failure.

  12. Functional hemodynamic monitoring

    PubMed Central

    Pinsky, Michael R; Payen, Didier

    2005-01-01

    Hemodynamic monitoring is a central component of intensive care. Patterns of hemodynamic variables often suggest cardiogenic, hypovolemic, obstructive, or distributive (septic) etiologies to cardiovascular insufficiency, thus defining the specific treatments required. Monitoring increases in invasiveness, as required, as the risk for cardiovascular instability-induced morbidity increases because of the need to define more accurately the diagnosis and monitor the response to therapy. Monitoring is also context specific: requirements during cardiac surgery will be different from those in the intensive care unit or emergency department. Solitary hemodynamic values are useful as threshold monitors (e.g. hypotension is always pathological, central venous pressure is only elevated in disease). Some hemodynamic values can only be interpreted relative to metabolic demand, whereas others have multiple meanings. Functional hemodynamic monitoring implies a therapeutic application, independent of diagnosis such as a therapeutic trial of fluid challenge to assess preload responsiveness. Newer methods for assessing preload responsiveness include monitoring changes in central venous pressure during spontaneous inspiration, and variations in arterial pulse pressure, systolic pressure, and aortic flow variation in response to vena caval collapse during positive pressure ventilation or passive leg raising. Defining preload responsiveness using these functional measures, coupled to treatment protocols, can improve outcome from critical illness. Potentially, as these and newer, less invasive hemodynamic measures are validated, they could be incorporated into such protocolized care in a cost-effective manner. PMID:16356240

  13. Artificial sweeteners produce the counterintuitive effect of inducing metabolic derangements.

    PubMed

    Swithers, Susan E

    2013-09-01

    The negative impact of consuming sugar-sweetened beverages on weight and other health outcomes has been increasingly recognized; therefore, many people have turned to high-intensity sweeteners like aspartame, sucralose, and saccharin as a way to reduce the risk of these consequences. However, accumulating evidence suggests that frequent consumers of these sugar substitutes may also be at increased risk of excessive weight gain, metabolic syndrome, type 2 diabetes, and cardiovascular disease. This paper discusses these findings and considers the hypothesis that consuming sweet-tasting but noncaloric or reduced-calorie food and beverages interferes with learned responses that normally contribute to glucose and energy homeostasis. Because of this interference, frequent consumption of high-intensity sweeteners may have the counterintuitive effect of inducing metabolic derangements.

  14. Artificial sweeteners produce the counterintuitive effect of inducing metabolic derangements

    PubMed Central

    Swithers, Susan E.

    2013-01-01

    The negative impact of consuming sugar-sweetened beverages on weight and other health outcomes has been increasingly recognized; therefore, many people have turned to high-intensity sweeteners like aspartame, sucralose, and saccharin as a way to reduce the risk of these consequences. However, accumulating evidence suggests that frequent consumers of these sugar substitutes may also be at increased risk of excessive weight gain, metabolic syndrome, type 2 diabetes, and cardiovascular disease. This paper discusses these findings and considers the hypothesis that consuming sweet-tasting but noncaloric or reduced-calorie food and beverages interferes with learned responses that normally contribute to glucose and energy homeostasis. Because of this interference, frequent consumption of high-intensity sweeteners may have the counterintuitive effect of inducing metabolic derangements. PMID:23850261

  15. Prenatal androgen excess programs metabolic derangements in pubertal female rats.

    PubMed

    Yan, Xiaonan; Dai, Xiaonan; Wang, Jing; Zhao, Nannan; Cui, Yugui; Liu, Jiayin

    2013-04-01

    Owing to the heterogeneity in the clinical symptoms of polycystic ovary syndrome (PCOS), the early pathophysiological mechanisms of PCOS remain unclear. Clinical, experimental, and genetic evidence supports an interaction between genetic susceptibility and the influence of maternal environment in the pathogenesis of PCOS. To determine whether prenatal androgen exposure induced PCOS-related metabolic derangements during pubertal development, we administrated 5α-dihydrotestosterone (DHT) in pregnant rats and observed their female offspring from postnatal 4 to 8 weeks. The prenatally androgenized (PNA) rats exhibited more numerous total follicles, cystic follicles, and atretic follicles than the controls. Fasting glucose, insulin, leptin levels, and homeostatic model assessment for insulin resistance were elevated in the PNA rats at the age of 5-8 weeks. Following intraperitoneal glucose tolerance tests, glucose and insulin levels did not differ between two groups; however, the PNA rats showed significantly higher 30- and 60-min glucose levels than the controls after insulin stimulation during 5-8 weeks. In addition, prenatal DHT treatment significantly decreased insulin-stimulated phosphorylation of AKT in the skeletal muscles of 6-week-old PNA rats. The abundance of IR substrate 1 (IRS1) and IRS2 was decreased in the skeletal muscles and liver after stimulation with insulin in the PNA group, whereas phosphorylation of insulin-signaling proteins was unaltered in the adipose tissue. These findings validate the contribution of prenatal androgen excess to metabolic derangements in pubertal female rats, and the impaired insulin signaling through IRS and AKT may result in the peripheral insulin resistance during pubertal development.

  16. Pistachio Nut Consumption Modifies Systemic Hemodynamics, Increases Heart Rate Variability, and Reduces Ambulatory Blood Pressure in Well‐Controlled Type 2 Diabetes: a Randomized Trial

    PubMed Central

    Sauder, Katherine A.; McCrea, Cindy E.; Ulbrecht, Jan S.; Kris‐Etherton, Penny M.; West, Sheila G.

    2014-01-01

    Background Managing cardiovascular risk factors is important for reducing vascular complications in type 2 diabetes, even in individuals who have achieved glycemic control. Nut consumption is associated with reduced cardiovascular risk; however, there is mixed evidence about the effect of nuts on blood pressure (BP), and limited research on the underlying hemodynamics. This study assessed the effect of pistachio consumption on BP, systemic hemodynamics, and heart rate variability in adults with well‐controlled type 2 diabetes. Methods and Results We enrolled 30 adults (40 to 74 years) with type 2 diabetes in a randomized, crossover, controlled feeding study. After a 2‐week run‐in period, participants consumed a low‐fat control diet (27% fat) containing low‐fat/high‐carbohydrate snacks and a moderate‐fat diet (33% fat) containing pistachios (20% of total energy) for 4 weeks each, separated by a 2‐week washout. Following each diet period, we assessed BP, systemic hemodynamics, and heart rate variability at rest and during acute mental stress, and, in a subset of participants (n=21), 24‐hour ambulatory BP. BP at rest and during stress did not differ between treatments. The pistachio diet significantly reduced total peripheral resistance (−3.7±2.9%, P=0.004), increased cardiac output (3.1±2.3%, P=0.002), and improved some measures of heart rate variability (all P<0.05). Systolic ambulatory BP was significantly reduced by 3.5±2.2 mm Hg (P=0.046) following the pistachio diet, with the greatest reduction observed during sleep (−5.7±2.6 mm Hg, P=0.052). Conclusions A moderate‐fat diet containing pistachios modestly improves some cardiovascular risk factors in adults with well‐controlled type 2 diabetes. Clinical Trial Registration URL: www.clinicaltrials.gov. Unique identifier: NCT00956735. PMID:24980134

  17. 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

  18. In Vivo Hemodynamic Performance Evaluation of Novel Electrocardiogram-Synchronized Pulsatile and Nonpulsatile Extracorporeal Life Support Systems in an Adult Swine Model.

    PubMed

    Wang, Shigang; Izer, Jenelle M; Clark, Joseph B; Patel, Sunil; Pauliks, Linda; Kunselman, Allen R; Leach, Donald; Cooper, Timothy K; Wilson, Ronald P; Ündar, Akif

    2015-07-01

    The primary objective of this study was to evaluate a novel electrocardiogram (ECG)-synchronized pulsatile extracorporeal life support (ECLS) system for adult partial mechanical circulatory support for adequate quality of pulsatility and enhanced hemodynamic energy generation in an in vivo animal model. The secondary aim was to assess end-organ protection during nonpulsatile versus synchronized pulsatile flow mode. Ten adult swine were randomly divided into a nonpulsatile group (NP, n = 5) and pulsatile group (P, n = 5), and placed on ECLS for 24 h using an i-cor system consisting of an i-cor diagonal pump, an iLA membrane ventilator, an 18 Fr femoral arterial cannula and a 23/25 Fr femoral venous cannula. Trials were conducted at a flow rate of 2.5 L/min using nonpulsatile or pulsatile mode (with assist ratio 1:1). Real-time pressure and flow data were recorded using a custom-based data acquisition system. To the best of our knowledge, the oxygenator and circuit pressure drops were the lowest for any available system in both groups. The ECG-synchronized i-cor ECLS system was able to trigger pulsatile flow in the porcine model. After 24-h ECLS, energy equivalent pressure, surplus hemodynamic energy, and total hemodynamic energy at preoxygenator and prearterial cannula sites were significantly higher in the P group than those in the NP group (P < 0.05). Urine output was higher in P versus NP (3379 ± 443 mL vs. NP, 2598 ± 1012 mL), and the P group seemed to require less inotropic support, but both did not reach statistical significances (P > 0.05). The novel i-cor system performed well in the nonpulsatile and ECG-synchronized pulsatile mode in an adult animal ECLS model. The iLA membrane oxygenator had an extremely lower transmembrane pressure gradient and excellent gas exchange capability. Our findings suggest that ECG-triggered pulsatile ECLS provides superior end-organ protection with improved renal function and systemic vascular

  19. Preservation Of Native Aortic Valve Flow And Full Hemodynamic Support With The TORVAD™ Using A Computational Model Of The Cardiovascular System

    PubMed Central

    Gohean, Jeffrey R.; George, Mitchell J.; Chang, Kay-Won; Larson, Erik R.; Pate, Thomas D.; Kurusz, Mark; Longoria, Raul G.; Smalling, Richard W.

    2014-01-01

    This paper describes the stroke volume selection and operational design for the TORVAD™, a synchronous, positive-displacement ventricular assist device (VAD). A lumped parameter model was used to simulate hemodynamics with the TORVAD™ compared to those under continuous flow VAD support. Results from the simulation demonstrated that a TORVAD™ with a 30 mL stroke volume ejecting with an early diastolic counterpulse provides comparable systemic support to the HeartMate II® (HMII) (cardiac output 5.7 L/min up from 3.1 L/min in simulated heart failure). By taking advantage of synchronous pulsatility, the TORVAD™ delivers full hemodynamic support with nearly half the VAD flow rate (2.7 L/min compared to 5.3 L/min for the HMII) by allowing the left ventricle to eject during systole, thus preserving native aortic valve flow (3.0 L/min compared to 0.4 L/min for the HMII, down from 3.1 L/min at baseline). The TORVAD™ also preserves pulse pressure (26.7 mmHg compared to 12.8 mmHg for the HMII, down from 29.1 mmHg at baseline). Preservation of aortic valve flow with synchronous pulsatile support could reduce the high incidence of aortic insufficiency and valve cusp fusion reported in patients supported with continuous flow VADs. PMID:25485562

  20. Cerebral Hemodynamics and Systemic Endothelial Function Are Already Impaired in Well-Controlled Type 2 Diabetic Patients, with Short-Term Disease

    PubMed Central

    Altavilla, Riccardo; Di Flaviani, Alessandra; Giordani, Ilaria; Malandrucco, Ilaria; Picconi, Fabiana; Passarelli, Francesco; Pasqualetti, Patrizio; Ercolani, Matilde; Vernieri, Fabrizio; Frontoni, Simona

    2013-01-01

    Objective Impaired cerebral vasomotor reactivity (VMR) and flow-mediated dilation (FMD) were found in selected subgroups of type 2 diabetes mellitus (T2DM) patients with long-term disease. Our study aimed to evaluate cerebral hemodynamics, systemic endothelial function and sympatho-vagal balance in a selected population of well-controlled T2DM patients with short-term disease and without cardiac autonomic neuropathy (CAN). Research Design and Methods Twenty-six T2DM patients with short-term (4.40±4.80 years) and well-controlled (HbA1C = 6.71±1.29%) disease, without any complications, treated with diet and/or metformin, were consecutively recruited. Eighteen controls, comparable by sex and age, were enrolled also. Results FMD and shear rate FMD were found to be reduced in T2DM subjects with short-term disease (8.5% SD 3.5 and 2.5 SD 1.3, respectively) compared to controls (15.4% SD 4.1 and 3.5 SD 1.4; p<.001 and p<.05). T2DM patients also displayed reduced VMR values than controls (39.4% SD 12.4 vs 51.7%, SD 15.5; p<.05). Sympatho-vagal balance was not different in T2DM patients compared to healthy subjects. FMD and shear rate FMD did not correlate with VMR in T2DM patients or in controls (p>.05). Conclusions In well-controlled T2DM patients with short-term disease cerebral hemodynamics and systemic endothelial function are altered while autonomic balance appeared to be preserved. PMID:24391751

  1. Post-operative consequences of hemodynamic optimization.

    PubMed

    Lazkani, A; Lebuffe, G

    2016-12-01

    Hemodynamic optimization begins with a medical assessment to identify the high-risk patients. This stratification is needed to customize the choice of hemodynamic support that is best adapted to the patient's level of risk, integrating the use of the least invasive procedures. The macro-circulatory hemodynamic approach aims to maintain a balance between oxygen supply (DO2) and oxygen demand (VO2). Volume replacement plays a crucial role based on the titration of fluid boluses according to their effect on measured stroke volume or indices of preload dependency. Good function of the microcirculatory system is the best guarantee to achieve this goal. An assessment of the DO2/VO2 ratio is needed for guidance in critical situations where tissue hypoxia may occur. Overall, all of these strategies are based on objective criteria to guide vascular replacement and/or tissue oxygenation in order to improve the patient's post-operative course by decreasing morbidity and hospital stay.

  2. Deranged iron status in psoriasis: the impact of low body mass

    PubMed Central

    Ponikowska, Malgorzata; Tupikowska, Malgorzata; Kasztura, Monika; Jankowska, Ewa A; Szepietowski, Jacek C

    2015-01-01

    Background Iron deficiency (ID) frequently complicates inflammatory-mediated chronic disorders, irrespective of anaemia. Psoriasis is a chronic, immune-mediated skin disease with systemic pro-inflammatory activation; thus, these patients may be prone to develop ID. ID adversely affects immune cells function, which can further contribute to disease progression. This study investigates iron status in psoriasis. Methods Serum concentrations of ferritin, transferrin saturation (Tsat), soluble transferrin receptor (sTfR), and hepcidin were assessed as the biomarkers of iron status in 39 patients with psoriasis (17 men, age: 47 ± 10 years) and 44 healthy subjects (30 men, age: 53 ± 6 years). Results Compared with healthy controls, patients with psoriasis demonstrated similar haematologic status but deranged iron status as evidenced by decreased Tsat and elevated sTfR (negative tissue iron balance) and low levels of hepcidin (depleted iron stores) (all P < 0.05 vs. controls). In patients, the levels of interleukin-6 (level of pro-inflammatory activation) significantly correlated with hepcidin (R = 0.54), but not with ferritin, Tsat, and sTfR. Biomarkers reflecting ID were not associated with the severity of the disease (assessed with the Psoriasis Area and Severity Index) but significantly correlated low body mass index (BMI). Patients with BMI < 24 kg/m2 compared with those with BMI ≥ 24 kg/m2 demonstrated lower levels of ferritin (40 ± 30 vs. 186 ± 128 ng/mL, P < 0.001) and hepcidin (4.9 ± 2.3 vs. 10.7 ± 6.7 ng/mL, P = 0.03). Conclusion Psoriasis is associated with deranged iron status characterized by depleted iron stores with concomitant unmet cellular iron requirements. The magnitude of these abnormalities is particularly strong in patients with low body mass index. Whether iron deficiency may become a therapeutic target in psoriasis needs to be investigated. PMID:26673741

  3. Activation of DOR Attenuates Anoxic K+ Derangement via Inhibition of Na+ Entry in Mouse Cortex

    PubMed Central

    Chao, Dongman; Bazzy-Asaad, Alia; Balboni, Gianfranco; Salvadori, Severo

    2008-01-01

    We have recently found that in the mouse cortex, activation of δ-opioid receptor (DOR) attenuates the disruption of K+ homeostasis induced by hypoxia or oxygen–glucose deprivation. This novel observation suggests that DOR may protect neurons from hypoxic/ischemic insults via the regulation of K+ homeostasis because the disruption of K+ homeostasis plays a critical role in neuronal injury under hypoxic/ischemic stress. The present study was performed to explore the ionic mechanism underlying the DOR-induced neuroprotection. Because anoxia causes Na+ influx and thus stimulates K+ leakage, we investigated whether DOR protects the cortex from anoxic K+ derangement by targeting the Na+-based K+ leakage. By using K+-sensitive microelectrodes in mouse cortical slices, we showed that 1) lowering Na+ concentration and substituting with impermeable N-methyl-D-glucamine caused a concentration-dependent attenuation of anoxic K+ derangement; 2) lowering Na+ concentration by substituting with permeable Li+ tended to potentiate the anoxic K+ derangement; and 3) the DOR-induced protection against the anoxic K+ responses was largely abolished by low-Na+ perfusion irrespective of the substituted cation. We conclude that external Na+ concentration greatly influences anoxic K+ derangement and that DOR activation likely attenuates anoxic K+ derangement induced by the Na+-activated mechanisms in the cortex. PMID:18203692

  4. 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

  5. Microbiological investigation of retrodiscal tissues from patients with advanced internal derangement of the temporomandibular joint.

    PubMed

    McIntosh, M; Dimitroulis, G

    2012-03-01

    The aim of this study was to investigate the presence of bacteria in samples of retrodiscal tissues taken from patients suffering from advanced internal derangement of the temporomandibular joint (TMJ). 12 fresh retrodiscal tissue samples were taken from 12 consecutive patients who underwent unilateral TMJ discectomy for advanced TMJ internal derangement (Wilkes stage IV). The retrodiscal tissue samples were stained and cultured for the presence of micro-organisms in microbiology laboratories. No evidence of bacteria or other micro-organisms was found in any of the tissue specimens procured from the TMJ. This study failed to identify the presence of bacteria or other micro-organisms in fresh retrodiscal tissue specimens of the TMJ in patients with advanced TMJ internal derangement.

  6. The development of a combined b-mode, ARFI, and spectral Doppler ultrasound imaging system for investigating cardiovascular stiffness and hemodynamics

    NASA Astrophysics Data System (ADS)

    Doherty, Joshua R.; Dumont, Douglas M.; Trahey, Gregg E.

    2011-03-01

    The progression of atherosclerotic disease, caused by the formation of plaques within arteries, is a complex process believed to be a function of the localized mechanical properties and hemodynamic loading associated with the arterial wall. It is hypothesized that measurements of vascular stiffness and wall-shear rate (WSR) may provide important information regarding vascular remodeling, endothelial function, and the growth of soft-lipid filled plaques that could help a clinician better diagnose a patient's risk of clinical events such as stroke. To that end, the approach taken in this work was to combine conventional B-mode, Acoustic Radiation Force Impulse (ARFI), Shear Wave Elasticity Imaging (SWEI), and spectral Doppler techniques into a single imaging system capable of simultaneously measuring the tissue displacements and WSR throughout the cardiac cycle and over several heartbeats. Implemented on a conventional scanner, the carotid arteries of human subjects were scanned to demonstrate the initial in vivo feasibility of the method. Two non-invasive ultrasound based imaging methods, SAD-SWEI and SAD-Gated Imaging, were developed that measure ARF-induced on-axis tissue displacements, off-axis transverse wave velocities, and WSR throughout the cardiac cycle. Human carotid artery scans were performed in vivo on 5 healthy subjects. Statistical differences were observed in both on-axis proximal wall displacements and transverse wave velocities during diastole compared to systole.

  7. Interaction between alpha 2-adrenergic and angiotensin II systems in the control of glomerular hemodynamics as assessed by renal micropuncture in the rat

    NASA Technical Reports Server (NTRS)

    Thomson, S. C.; Gabbai, F. B.; Tucker, B. J.; Blantz, R. C.

    1992-01-01

    The hypothesis that renal alpha 2 adrenoceptors influence nephron filtration rate (SNGFR) via interaction with angiotensin II (AII) was tested by renal micropuncture. The physical determinants of SNGFR were assessed in adult male Munich Wistar rats 5-7 d after ipsilateral surgical renal denervation (DNX). DNX was performed to isolate inhibitory central and presynaptic alpha 2 adrenoceptors from end-organ receptors within the kidney. Two experimental protocols were employed: one to test whether prior AII receptor blockade with saralasin would alter the glomerular hemodynamic response to alpha 2 adrenoceptor stimulation with the selective agonist B-HT 933 under euvolemic conditions, and the other to test whether B-HT 933 would alter the response to exogenous AII under conditions of plasma volume expansion. In euvolemic rats, B-HT 933 caused SNGFR to decline as the result of a decrease in glomerular ultrafiltration coefficient (LpA), an effect that was blocked by saralasin. After plasma volume expansion, B-HT 933 showed no primary effect on LpA but heightened the response of arterial blood pressure, glomerular transcapillary pressure gradient, and LpA to AII. The parallel results of these converse experiments suggest a complementary interaction between renal alpha 2-adrenergic and AII systems in the control of LpA.

  8. Ocular hemodynamics during isometric exercise.

    PubMed

    Kiss, B; Dallinger, S; Polak, K; Findl, O; Eichler, H G; Schmetterer, L

    2001-01-01

    The autoregulatory capacity of the human retina is well documented, but the pressure-flow relationship of the human choroid is still a matter of controversy. Recent data, using laser Doppler flowmetry to measure choroidal blood flow, indicate that the choroid has some autoregulatory potential, whereas most data using other techniques for the assessment of choroidal hemodynamics indicate that the choroidal pressure-flow curve is linear. We used a new laser interferometric technique to characterize choroidal blood flow during isometric exercise. Twenty healthy subjects performed squatting for 6 min during normocapnia and during inhalation of 5% CO2 and 95% air. Ocular fundus pulsation amplitude, flow velocities in the ophthalmic artery, intraocular pressure, and systemic hemodynamics were measured in 2-min intervals. To gain information on choroidal blood flow fundus pulsation amplitude was corrected for changes in flow pulsatility using data from the ophthalmic artery and for changes in pulse rate. Ocular perfusion pressure was calculated from mean arterial pressure and intraocular pressure. The ocular pressure-flow relationship was calculated by sorting data according to ascending ocular perfusion pressure values. In a pilot study in 6 healthy subjects comparable ocular pressure flow relationships were obtained when choroidal blood flow was assessed with the method described above and with laser Doppler flowmetry. In the main study isometric exercise caused a significant increase in mean arterial pressure (56%, P < 0.001), pulse rate (84%, P < 0.001), and intraocular pressure (37%, P 0.004), but decreased fundus pulsation amplitude (-36%, P < 0.001). Significant deviations from baseline choroidal blood flow were observed only at ocular perfusion pressures >69% during normocapnia and 70% during hypercapnia. Our data indicate that during isometric exercise the choroid has a high capacity to keep blood flow constant despite changes in perfusion pressure and that this

  9. CENTRAL NERVOUS MECHANISMS IN CIRCULATION REGULATION AND FUNCTIONAL DERANGEMENT (HYPERTENSION).

    DTIC Science & Technology

    BLOOD CIRCULATION, *CENTRAL NERVOUS SYSTEM, * HYPERTENSION , AUTONOMIC NERVOUS SYSTEM, ELECTROENCEPHALOGRAPHY, ELECTROPHYSIOLOGY, CHEMORECEPTORS...PERCEPTION, CARDIOVASCULAR SYSTEM, PATHOLOGY, REFLEXES, BEHAVIOR, BLOOD PRESSURE , ANOXIA, BRAIN, ITALY.

  10. Neonatal Thymulin Gene Therapy Prevents Ovarian Dysgenesis and Attenuates Reproductive Derangements in Nude Female Mice

    PubMed Central

    Reggiani, Paula C.; Barbeito, Claudio G.; Zuccolilli, Gustavo O.; Cónsole, Gloria M.; Flamini, Alicia M.; Dardenne, Mireille

    2012-01-01

    Congenitally athymic (nude) female mice show severe ovarian dysgenesis after puberty, which seems to be consequential to a number of neuroendocrine derangements described in these mutants. Thus, considerable evidence suggests that thymulin, a thymic peptide, may be involved in thymus-pituitary communication. In order to clarify the relevance of thymulin for the maturation of the female reproductive system, we assessed at hypothalamic, pituitary, ovarian, and uterine level the preventive action of neonatal thymulin gene therapy (NTGT) on the changes that typically occur after puberty in congenitally athymic female mice. We injected (im) an adenoviral vector harboring a synthetic DNA sequence encoding a biologically active analog of thymulin, methionine-serum thymic factor, in newborn nude mice (which are thymulin deficient) and killed the animals at 70–71 d of age. NTGT in the athymic mice restored the serum thymulin levels. Morphometric analysis revealed that athymic nudes have reduced numbers of brain GnRH neurons and pituitary gonadotropic cells as compared with heterozygous controls. NTGT prevented these changes and also rescued the premature ovarian failure phenotype typically observed in athymic nude mice (marked reduction in the number of antral follicles and corpora lutea, increase in atretic follicles). Serum estrogen, but not progesterone, levels were low in athymic nudes, a reduction that was partially prevented by NTGT. Little to no morphological changes were observed in the endometrium of female nudes. The delay in the age of vaginal opening that occurs in athymic nudes was significantly prevented by NTGT. Our results suggest that thymulin plays a relevant physiologic role in the thymus-hypothalamo-pituitary-gonadal axis. PMID:22700775

  11. Neonatal thymulin gene therapy prevents ovarian dysgenesis and attenuates reproductive derangements in nude female mice.

    PubMed

    Reggiani, Paula C; Barbeito, Claudio G; Zuccolilli, Gustavo O; Cónsole, Gloria M; Flamini, Alicia M; Dardenne, Mireille; Goya, Rodolfo G

    2012-08-01

    Congenitally athymic (nude) female mice show severe ovarian dysgenesis after puberty, which seems to be consequential to a number of neuroendocrine derangements described in these mutants. Thus, considerable evidence suggests that thymulin, a thymic peptide, may be involved in thymus-pituitary communication. In order to clarify the relevance of thymulin for the maturation of the female reproductive system, we assessed at hypothalamic, pituitary, ovarian, and uterine level the preventive action of neonatal thymulin gene therapy (NTGT) on the changes that typically occur after puberty in congenitally athymic female mice. We injected (im) an adenoviral vector harboring a synthetic DNA sequence encoding a biologically active analog of thymulin, methionine-serum thymic factor, in newborn nude mice (which are thymulin deficient) and killed the animals at 70-71 d of age. NTGT in the athymic mice restored the serum thymulin levels. Morphometric analysis revealed that athymic nudes have reduced numbers of brain GnRH neurons and pituitary gonadotropic cells as compared with heterozygous controls. NTGT prevented these changes and also rescued the premature ovarian failure phenotype typically observed in athymic nude mice (marked reduction in the number of antral follicles and corpora lutea, increase in atretic follicles). Serum estrogen, but not progesterone, levels were low in athymic nudes, a reduction that was partially prevented by NTGT. Little to no morphological changes were observed in the endometrium of female nudes. The delay in the age of vaginal opening that occurs in athymic nudes was significantly prevented by NTGT. Our results suggest that thymulin plays a relevant physiologic role in the thymus-hypothalamo-pituitary-gonadal axis.

  12. Hemodynamic and autonomic nervous system responses to mixed meal ingestion in healthy young and old subjects and dysautonomic patients with postprandial hypotension

    NASA Technical Reports Server (NTRS)

    Lipsitz, L. A.; Ryan, S. M.; Parker, J. A.; Freeman, R.; Wei, J. Y.; Goldberger, A. L.

    1993-01-01

    BACKGROUND. Although postprandial hypotension is a common cause of falls and syncope in elderly persons and in patients with autonomic insufficiency, the pathophysiology of this disorder remains unknown. METHODS AND RESULTS. We examined the hemodynamic, splanchnic blood pool, plasma norepinephrine (NE), and heart rate (HR) power spectra responses to a standardized 400-kcal mixed meal in 11 healthy young (age, 26 +/- 5 years) and nine healthy elderly (age, 80 +/- 5 years) subjects and 10 dysautonomic patients with symptomatic postprandial hypotension (age, 65 +/- 16 years). Cardiac and splanchnic blood pools were determined noninvasively by radionuclide scans, and forearm vascular resistance was determined using venous occlusion plethysmography. In healthy young and old subjects, splanchnic blood volume increased, but supine blood pressure remained unchanged after the meal. In both groups, HR increased and systemic vascular resistance remained stable. Forearm vascular resistance and cardiac index increased after the meal in elderly subjects, whereas these responses were highly variable and of smaller magnitude in the young. Young subjects demonstrated postprandial increases in low-frequency HR spectral power, representing cardiac sympatho-excitation, but plasma NE remained unchanged. In elderly subjects, plasma NE increased after the meal but without changes in the HR power spectrum. Patients with dysautonomia had a large postprandial decline in blood pressure associated with no change in forearm vascular resistance, a fall in systemic vascular resistance, and reduction in left ventricular end diastolic volume index. HR increased in these patients but without changes in plasma NE or the HR power spectrum. CONCLUSIONS. 1) In healthy elderly subjects, the maintenance of blood pressure homeostasis after food ingestion is associated with an increase in HR, forearm vascular resistance, cardiac index, and plasma NE. In both young and old, systemic vascular resistance is

  13. Evaluation of Intrahepatic Perfusion on Fusion Imaging Using a Combined CT/SPECT System: Influence of Anatomic Variations on Hemodynamic Modification Before Installation of Implantable Port Systems for Hepatic Arterial Infusion Chemotherapy

    SciTech Connect

    Ikeda, Osamu Tamura, Yoshitaka; Nakasone, Yutaka; Shiraishi, Shinya; Kawanaka, Kouichi; Tomiguchi, Seiji; Takamori, Hiroshi; Chikamoto, Akira; Kanemitsu, Keiichirou; Yamashita, Yasuyuki

    2007-06-15

    Background. In some patients with hepatic tumors, anatomic variations in the hepatic arteries may require hemodynamic modification to render effective hepatic arterial infusion chemotherapy delivered via implantable port systems. We used a combined CT/SPECT system to obtain fused images of the intrahepatic perfusion patterns in patients with such anatomic variations and assessed their effects on the treatment response of hepatic tumors. Methods. Using a combined SPECT/CT system, we obtained fused images in 110 patients with malignant liver tumors (n = 75) or liver metastasis from unresectable pancreatic cancer (n = 35). Patients with anatomic hepatic arteries variations underwent hemodynamic modification before the placement of implantable port systems for hepatic arterial infusion chemotherapy. We evaluated their intrahepatic perfusion patterns and the initial treatment response of their liver tumors. The perfusion patterns on the fused images were classified as homogeneous, local hypoperfusion, and/or perfusion defect. Using the WHO criteria of complete response (CR), partial response (PR), no change (NC), and progressive disease (PD), we evaluated the patients' tumor responses after 3 months on multislice helical CT scans. The treatment was regarded as effective in patients who achieved a complete response or partial response. Results. Anatomic hepatic artery variations were present in 15 of the 110 patients (13.6%); 5 manifested replacement of the left hepatic artery (LHA), 8 of the right hepatic artery (RHA), and 1 each had replacement of the RHA and LHA, and replacement of the LHA plus an accessory RHA. In 13 of these 15 patients (87%), occlusion with metallic coils was successful. On fusion imaging, the perfusion patterns were recorded as homogeneous in 6 patients (43%), as hypoperfusion in 7 (50%), and 1 patient had a perfusion defect (7.1%) in the embolized arterial region. Of the 8 patients with RHA replacement, 4 manifested a homogeneous distribution and

  14. Suicide as a derangement of the self-sacrificial aspect of eusociality.

    PubMed

    Joiner, Thomas E; Hom, Melanie A; Hagan, Christopher R; Silva, Caroline

    2016-04-01

    Building upon the idea that humans may be a eusocial species (i.e., rely on multigenerational and cooperative care of young, utilize division of labor for successful survival), we conjecture that suicide among humans represents a derangement of the self-sacrificial aspect of eusociality. In this article, we outline the characteristics of eusociality, particularly the self-sacrificial behavior seen among other eusocial species (e.g., insects, shrimp, mole rats). We then discuss parallels between eusocial self-sacrificial behavior in nonhumans and suicide in humans, particularly with regard to overarousal states, withdrawal phenomena, and perceptions of burdensomeness. In so doing, we make the argument that death by suicide among humans is an exemplar of psychopathology and is due to a derangement of the self-sacrificial behavioral suite found among eusocial species. Implications and future directions for research are also presented.

  15. Internal derangements of the temporomandibular joint: findings in the pediatric age group

    SciTech Connect

    Katzberg, R.W.; Tallents, R.H.; Hayakawa, K.; Miller, T.L.; Goske, M.J.; Wood, B.P.

    1985-01-01

    Findings in 31 pediatric patients with pain and dysfunction of the temporomandibular joint (TMJ) are reported. The average age was 14 years and the average duration of symptoms was 21.4 months. Internal derangements were found in 29 patients (94%) and degenerative arthritis in 13 (42%). In 12 patients (39%), the problem could be traced to an injury to the jaw. Secondary condylar hypoplasia was associated with the meniscal abnormality in 3 patients (10%). Further awareness of internal derangements of the TMJ in the pediatric population should permit greater recognition of their etiology. It is important that threatment be initiated as soon as possible, not only to minimize the development of osseous disease in young adults but also to prevent facial growth deformities.

  16. Metabolic and Hormonal Derangements in Pulmonary Hypertension: From Mouse to Man

    PubMed Central

    Pugh, Meredith E.; Hemnes, Anna R.

    2010-01-01

    Summary Pulmonary arterial hypertension (PAH) is a complex disease with significant morbidity and mortality. Recent animal and human studies have highlighted abnormalities in regulation and metabolism of insulin, sex hormones, adipokines, and lipids that may play a role in disease development. Mouse studies suggest features of the metabolic syndrome including insulin resistance, deficiencies in PPARγ and apolipoprotein E, and low adiponectin are linked to development of PAH. In humans, insulin resistance, the metabolic syndrome, and low levels of high-density lipoprotein have been associated with PAH. In addition, abnormal metabolism of estrogens has been demonstrated in human and animal models of PAH, suggesting an important relationship of sex hormones and pulmonary vascular disease. Improved understanding of how metabolic and hormonal derangements relate to development and progression of pulmonary hypertension may lead to better disease therapies and understanding of potential risk factors. This review will focus on the animal and human data regarding metabolic and sex hormone derangements in PAH. PMID:20939841

  17. Internal derangements of the temporomandibular joint: A review of the anatomy, diagnosis, and management

    PubMed Central

    Young, Andrew L.

    2015-01-01

    Internal derangements of the temporomandibular joint are conditions in which the articular disc has become displaced from its original position the condylar head. Relevant anatomic structures and their functional relationships are briefly discussed. The displacement of the disc can result in numerous presentations, with the most common being disc displacement with reduction (with or without intermittent locking), and disc displacement without reduction (with or without limited opening). These are described in this article according to the standardized Diagnostic Criteria for Temporomandibular Disorders, as well as the less common posterior disc displacement. Appropriate management usually ranges from patient education and monitoring to splints, physical therapy, and medications. In rare and select cases, surgery may be necessary. However, in for the majority of internal derangements, the prognosis is good, particularly with conservative care. PMID:26929478

  18. Vasopressin Improves Hemodynamic Status in Infants with Congenital Diaphragmatic Hernia

    PubMed Central

    Acker, Shannon N.; Kinsella, John P.; Abman, Steven H.; Gien, Jason

    2014-01-01

    Objective To assess the ability of vasopressin to stabilize hemodynamics in infants with systemic hypotension secondary to congenital diaphragmatic hernia (CDH). Study design A retrospective chart review was performed to identify 13 patients with CDH treated with vasopressin for refractory hypotension, to assess the effect of vasopressin on pulmonary and systemic hemodynamics and gas exchange in this setting. Data collected included demographics, respiratory support, inotropic agents, pulmonary and systemic hemodynamics, urine output, and serum and urine sodium levels during vasopressin therapy. Results Vasopressin therapy increased mean arterial pressure and decreased pulmonary: systemic pressure ratio, heart rate and FiO2. In 6 of 13 patients, ECMO was no longer indicated after vasopressin treatment. Improvement in left ventricular (LV) function and oxygenation index after vasopressin initiation were associated with a decreased need for ECMO. Prolonged vasopressin treatment was associated with hyponatremia, increased urine output and increased urine sodium. Conclusions Vasopressin stabilized systemic hemodynamics without adverse effects on pulmonary hemodynamics in a subset of infants with CDH. Our results suggest a potential role for vasopressin therapy in patients with CDH with catecholamine resistant refractory hypotension. PMID:24840762

  19. 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

  20. Nutritional and Metabolic Derangements in Pancreatic Cancer and Pancreatic Resection

    PubMed Central

    Gilliland, Taylor M.; Villafane-Ferriol, Nicole; Shah, Kevin P.; Shah, Rohan M.; Tran Cao, Hop S.; Massarweh, Nader N.; Silberfein, Eric J.; Choi, Eugene A.; Hsu, Cary; McElhany, Amy L.; Barakat, Omar; Fisher, William; Van Buren, George

    2017-01-01

    Pancreatic cancer is an aggressive malignancy with a poor prognosis. The disease and its treatment can cause significant nutritional impairments that often adversely impact patient quality of life (QOL). The pancreas has both exocrine and endocrine functions and, in the setting of cancer, both systems may be affected. Pancreatic exocrine insufficiency (PEI) manifests as weight loss and steatorrhea, while endocrine insufficiency may result in diabetes mellitus. Surgical resection, a central component of pancreatic cancer treatment, may induce or exacerbate these dysfunctions. Nutritional and metabolic dysfunctions in patients with pancreatic cancer lack characterization, and few guidelines exist for nutritional support in patients after surgical resection. We reviewed publications from the past two decades (1995–2016) addressing the nutritional and metabolic status of patients with pancreatic cancer, grouping them into status at the time of diagnosis, status at the time of resection, and status of nutritional support throughout the diagnosis and treatment of pancreatic cancer. Here, we summarize the results of these investigations and evaluate the effectiveness of various types of nutritional support in patients after pancreatectomy for pancreatic adenocarcinoma (PDAC). We outline the following conservative perioperative strategies to optimize patient outcomes and guide the care of these patients: (1) patients with albumin < 2.5 mg/dL or weight loss > 10% should postpone surgery and begin aggressive nutrition supplementation; (2) patients with albumin < 3 mg/dL or weight loss between 5% and 10% should have nutrition supplementation prior to surgery; (3) enteral nutrition (EN) should be preferred as a nutritional intervention over total parenteral nutrition (TPN) postoperatively; and, (4) a multidisciplinary approach should be used to allow for early detection of symptoms of endocrine and exocrine pancreatic insufficiency alongside implementation of appropriate

  1. Hemodynamic coherence and the rationale for monitoring the microcirculation

    PubMed Central

    2015-01-01

    This article presents a personal viewpoint of the shortcoming of conventional hemodynamic resuscitation procedures in achieving organ perfusion and tissue oxygenation following conditions of shock and cardiovascular compromise, and why it is important to monitor the microcirculation in such conditions. The article emphasizes that if resuscitation procedures are based on the correction of systemic variables, there must be coherence between the macrocirculation and microcirculation if systemic hemodynamic-driven resuscitation procedures are to be effective in correcting organ perfusion and oxygenation. However, in conditions of inflammation and infection, which often accompany states of shock, vascular regulation and compensatory mechanisms needed to sustain hemodynamic coherence are lost, and the regional circulation and microcirculation remain in shock. We identify four types of microcirculatory alterations underlying the loss of hemodynamic coherence: type 1, heterogeneous microcirculatory flow; type 2, reduced capillary density induced by hemodilution and anemia; type 3, microcirculatory flow reduction caused by vasoconstriction or tamponade; and type 4, tissue edema. These microcirculatory alterations can be observed at the bedside using direct visualization of the sublingual microcirculation with hand-held vital microscopes. Each of these alterations results in oxygen delivery limitation to the tissue cells despite the presence of normalized systemic hemodynamic variables. Based on these concepts, we propose how to optimize the volume of fluid to maximize the oxygen-carrying capacity of the microcirculation to transport oxygen to the tissues. PMID:26729241

  2. 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.

  3. 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

  4. Derangement, osteoarthritis, and rheumatoid arthritis of the temporomandibular joint: implications, diagnosis, and management.

    PubMed

    Broussard, Jack S

    2005-04-01

    Temporomandibular joint (TMJ) dysfunction is often believed to bea young person's malady. However, geriatric patients also present with clinical findings of TMJ clicking, locking, crepitation, limited opening, and pain. With our aging population and the high prevalence of rheumatic and musculoskeletal diseases in the elderly, it is important to understand the etiopathogenesis, clinical presentation, and management of derangement, rheumatoid arthritis, and osteoarthritis of the TMJ. Although arthritis of the TMJ usually causes only mild-to-moderate dysfunction in older patients, they present challenges related to medication use and comorbidity. This article presents the most recent understanding and therapeutic protocols for patient diagnosis and management.

  5. 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

  6. 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.

  7. Efficacy of arthroscopic surgery and midlaser treatments for chronic temporomandibular joint articular disc derangement following motor vehicle accident.

    PubMed

    McNamara, D C; Rosenberg, I; Jackson, P A; Hogben, J

    1996-12-01

    As a result of motor vehicle accident soft-tissue injury, temporomandibular joint articular disc derangement may develop and persist despite symptomatic treatment and medication. This study reports the effectiveness of management directed at controlling the TMJ and masticatory neuromuscular pain dysfunction with a TMJ/interocclusal stabilization appliance, specific biofeedback and ultrasound therapy. Following these conservative measures residual articular disc derangement was present in some subjects who were offered arthroscopic surgery and infrared midlaser with TMJ/occlusal stabilization. Twenty subjects with residual disc derangement were randomly selected into two groups with and without arthroscopic surgery, and analyses of variance made before treatment, 12 months after conservative procedures, 3 months following arthroscopic surgery and midlaser therapy and 3 years since commencement of management. Dependent variables compared were pain-discomfort, Clinical Dysfunction Index, articular disc derangement and maximal voluntary jaw opening. Conservative management alone provided significant reduction of pain-discomfort and clinical dysfunction, while arthroscopic surgery resulted in significant reduction in articular disc derangement. The midlaser with TMJ/occlusal stabilization maintained significant improvement in the variables (p < 0.01) for both groups. The common articular deviations in form found at arthroscopy were soft tissue alteration with hyperaemia, synovitis, synovial membrane and posterior attachment folding with connective tissue hyperplasia, and disc displacement with fibrous adhesions. The Global Status Score of pain behaviour compared with residual function, confirmed the presence of greater pain before treatment commenced.

  8. [Hemorheology, hemodynamics and microcirculation. 1].

    PubMed

    Larcan, A; Stoltz, J F

    1989-01-01

    The microcirculation constitutes an ubiquitous vascular network presenting a mesh pattern, and comprising different types of vessels, arterioles, small veins, capillaries, arteriovenous shunts or similar structures, and lymphatics. Many dimensions have to be recognized, or simply mentioned, if one is to understand the hemodynamic and hemorheological particulars of this territory, which differ, in many aspects, from those specific to the macrocirculation (number and length of the vessels, diameter and cross section, intercapillary distance, geometric characteristics, intravascular pressure, pressure gradient, pressure-volume relationship, flow rate, mean velocity of plasma and RBC, velocity profile, local hematocrit, in situ viscosity, kinematic viscosity, wall shearing conditions, local oxygen transport, aggregation and deformability of RBC, leukocyte properties, etc.). The flow rate in capillary tubes and capillary vessels of the living organism varies with many factors, such as proximal hemodynamics, hemorheological characteristics of blood (fibrinogen, macro- and micro-hematocrit), some known effects (Farheus, Farheus Lindqvist), local diameter, the plasma layer which plays the role of the limiting layer, the endothelial film, the wall effect, and so forth. Models of the circulation have been propounded, none of which takes into account the whole of these phenomena due to their great complexity. Hemodynamic and hemorheological interactions provide for a better understanding of certain concepts, such as vascular resistance, hindrance, capacitance, local flow rates, real capillary opening and closing, development of two-directional functional shunts, autoregulation, pressure-volume relationship, critical closing pressure, circulatory current slowing effect, sequelae of intravascular aggregation of formed blood elements.

  9. FNDC5 overexpression and irisin ameliorate glucose/lipid metabolic derangements and enhance lipolysis in obesity.

    PubMed

    Xiong, Xiao-Qing; Chen, Dan; Sun, Hai-Jian; Ding, Lei; Wang, Jue-Jin; Chen, Qi; Li, Yue-Hua; Zhou, Ye-Bo; Han, Ying; Zhang, Feng; Gao, Xing-Ya; Kang, Yu-Ming; Zhu, Guo-Qing

    2015-09-01

    Irisin is a cleaved and secreted fragment of fibronectin type III domain containing 5 (FNDC5), and contributes to the beneficial effects of exercise on metabolism. Here we report the therapeutical effects of FNDC5/irisin on metabolic derangements and insulin resistance in obesity, and show the lipolysis effect of irisin and its signal molecular mechanism. In obese mice, lentivirus mediated-FNDC5 overexpression enhanced energy expenditure, lipolysis and insulin sensitivity, and reduced hyperlipidemia, hyperglycemia, hyperinsulinism, blood pressure and norepinephrine levels; it increased hormone-sensitive lipase (HSL) expression and phosphorylation, and reduced perilipin level and adipocyte diameter in adipose tissues. Subcutaneous perfusion of irisin reduced hyperlipidemia and hyperglycemia, and improved insulin resistance. Either FNDC5 overexpression or irisin perfusion only induced a tendency toward a slight decrease in body weight in obese mice. In 3T3-L1 adipocytes, irisin enhanced basal lipolysis rather than isoproterenol-induced lipolysis, which were prevented by inhibition of adenylate cyclase or PKA; irisin increased the HSL and perilipin phosphorylation; it increased PKA activity, and cAMP and HSL mRNA levels, but reduced perilipin expression. These results indicate that FNDC5/irisin ameliorates glucose/lipid metabolic derangements and insulin resistance in obese mice, and enhances lipolysis via cAMP-PKA-HSL/perilipin pathway. FNDC5 or irisin can be taken as an effective therapeutic strategy for metabolic disorders.

  10. Impaired cognitive performance in neuronal nitric oxide synthase knockout mice is associated with hippocampal protein derangements.

    PubMed

    Kirchner, Liselotte; Weitzdoerfer, Rachel; Hoeger, Harald; Url, Angelika; Schmidt, Peter; Engelmann, Mario; Villar, Santiago Rosell; Fountoulakis, Michael; Lubec, Gert; Lubec, Barbara

    2004-12-01

    Nitric oxide is implicated in modulation of memory and pharmacological as well as genetic inhibition of neuronal nitric oxide synthase (nNOS) leads to impaired cognitive function. We therefore decided to study learning and memory functions and cognitive flexibility in the Morris water maze (MWM) in 1-month-old male mice lacking nNOS (nNOS KO). Hippocampal protein profiling was carried out to possibly link protein derangement to impaired cognitive function. Two-dimensional gel electrophoresis with in-gel digestion of spots and subsequent MALDI-TOF identification of proteins and quantification of proteins using specific software was applied. In the memory as well as in the relearning task of the MWM, most of the nNOS KO failed to find the submerged platform within a given time. Proteomic evaluation of hippocampus, the main anatomical structure computing cognitive functions, revealed aberrant expression of a synaptosomal associated protein of the exocytotic machinery (NSF), glycolytic enzymes, chaperones 78 kDa glucose-regulated protein, T-complex protein 1; the signaling structure guanine nucleotide-binding protein G(I)/G(S)/G(T) and heterogeneous nuclear ribonucleoprotein H of the splicing machinery. We conclude that nNOS knockout mice show impaired spatial performance in the MWM, a finding that may be either linked to direct effects of nNOS/NO and/or to specific hippocampal protein derangements.

  11. Mentha piperita in nephrotoxicity – a possible intervention to ameliorate renal derangements associated with gentamicin

    PubMed Central

    Ullah, Naveed; Khan, Mir Azam; Khan, Taous; Asif, Afzal Haq; Ahmad, Waqar

    2014-01-01

    Objective: Free radical generation has a strong role in the pathogenesis of renal damage associated with the use of gentamicin. Therefore, the present study was carried out to evaluate the renoprotective effect of Mentha piperita against gentamicin induced nephrotoxicity. Materials and Methods: A total of 24 male rabbits were divided into 4 groups receiving normal saline, gentamicin, M. piperita extract and co-therapy of extract and gentamicin respectively. Gentamicin was provided as 80 mg/kg/day intramuscularly and extract was given 200 mg/kg/day orally for a period of 21 days. Serum and urinary biochemical parameters and histological changes were studied for each group. The impact of the extract on the antibacterial action of gentamicin was also evaluated. Results: Animals treated with gentamicin showed derangements in serum and urinary biochemical parameters. These alterations were reversed by treatment with M. piperita extract. The histological changes showed in gentamicin group were also reverted by treatment with the extract. Further the plant did not influence the efficacy of gentamicin with respect to its antimicrobial properties. Conclusion: Co-therapy of M. piperita with gentamicin successfully attenuated biochemical kidney functioning derangements and morphological changes associated with gentamicin. PMID:24741187

  12. Clinical evaluation of physical therapy in the management of internal derangement of the temporomandibular joint.

    PubMed

    Kirk, W S; Calabrese, D K

    1989-02-01

    This clinical cross-sectional study examines the favorable functional improvement in patients undergoing physical therapy for mild to moderate internal disc derangements of the temporomandibular joint. Sixty-eight patients with internal derangements were treated with physical therapeutic modalities as described by Rocabado. A success rate of 86% was achieved in patients with early- to mid-opening and late- to mid-closing clicks of the temporomandibular joint. Approximately one third of these patients required short-term occlusal bite appliances to assist in their management. A success rate of 7% was achieved in patients with late-opening and late-closing clicks. No patient with clicking on mediolateral movement was successfully managed with physical therapy. Likewise, patients with nonreducing anteriorly displaced discs of the temporomandibular joint did not respond well to physical therapy. Pain management was evaluated separately and showed subjective improvement in 82% of patients with mild to moderate disc dysfunction and pain. Only 29% of patients with late-opening clicking or locked joints experienced pain relief. When patients were classified according to occurrence of the clicking phenomenon, interesting trends relating to duration of symptoms were found. Twenty-two patients who did not respond favorably to physical therapy underwent surgical procedures. Findings in these patients offer suggestions about why nonsurgical therapy is not successful in certain cases.

  13. 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)

  14. Development of a custom-designed echo particle image velocimetry system for multi-component hemodynamic measurements: system characterization and initial experimental results

    NASA Astrophysics Data System (ADS)

    Liu, Lingli; Zheng, Hairong; Williams, Logan; Zhang, Fuxing; Wang, Rui; Hertzberg, Jean; Shandas, Robin

    2008-03-01

    We have recently developed an ultrasound-based velocimetry technique, termed echo particle image velocimetry (Echo PIV), to measure multi-component velocity vectors and local shear rates in arteries and opaque fluid flows by identifying and tracking flow tracers (ultrasound contrast microbubbles) within these flow fields. The original system was implemented on images obtained from a commercial echocardiography scanner. Although promising, this system was limited in spatial resolution and measurable velocity range. In this work, we propose standard rules for characterizing Echo PIV performance and report on a custom-designed Echo PIV system with increased spatial resolution and measurable velocity range. Then we employed this system for initial measurements on tube flows, rotating flows and in vitro carotid artery and abdominal aortic aneurysm (AAA) models to acquire the local velocity and shear rate distributions in these flow fields. The experimental results verified the accuracy of this technique and indicated the promise of the custom Echo PIV system in capturing complex flow fields non-invasively.

  15. A derangement of the brain wound healing process may cause some cases of Alzheimer's disease.

    PubMed

    Lehrer, Steven; Rheinstein, Peter H

    2016-08-01

    A derangement of brain wound healing may cause some cases of Alzheimer's disease. Wound healing, a highly complex process, has four stages: hemostasis, inflammation, repair, and remodeling. Hemostasis and the initial phases of inflammation in brain tissue are typical of all vascularized tissue, such as skin. However, distinct differences arise in brain tissue during the later stages of inflammation, repair, and remodeling, and closely parallel the changes of Alzheimer's disease. Our hypothesis -- Alzheimer's disease is brain wound healing gone awry at least in some cases -- could be tested by measuring progression with biomarkers for the four stages of wound healing in humans or appropriate animal models. Autopsy studies might be done. Chronic traumatic encephalopathy might also result from the brain wound healing process.

  16. Histologic appearance of the bilaminar zone in internal derangement of the temporomandibular joint.

    PubMed

    Hall, M B; Brown, R W; Baughman, R A

    1984-10-01

    Light microscopy was used to examine twenty-six specimens of bilaminar zone tissue excised during surgery for correction of internal derangement of the temporamandibular joint. Each of the specimens was examined for the presence of inflammation, amount of vascularity, arterial wall thickness, presence of fat, appearance of collagen, and amount of elastin present. Wide variation in the histologic appearance was noted among the specimens, although no significant inflammation was observed in any of them. Some indications that this tissue is undergoing adaptive changes include the presence of thickened arterial walls suggesting a decreased blood flow and the tendency for decreased amounts of elastin to be associated with denser-appearing collagen. There is also a tendency for patients with complete dislocation to exhibit less elastin than those with partial dislocation of the meniscus.

  17. Reactive arthritis in relation to internal derangements of the temporomandibular joint: a case control study.

    PubMed

    Lund, Bodil; Holmlund, Anders; Wretlind, Bengt; Jalal, Shah; Rosén, Annika

    2015-09-01

    The aim of this study was to find out if reactive arthritis was involved in the aetiology of chronic closed lock of the temporomandibular joint (TMJ) by looking for bacterial antigens in the synovial membrane of the TMJ, and by studying the antibody serology and carriage of human leucocyte antigen (HLA) B27 in patients with chronic closed lock. Patients with reciprocal clicking and healthy subjects acted as controls. We studied a total of 43 consecutive patients, 15 with chronic closed lock, 13 with reciprocal clicking, and 15 healthy controls with no internal derangements of the TMJ. Venous blood samples were collected from all subjects for measurement of concentrations of HLA tissue antigen and serology against Chlamydia trachomatis, Yersinia enterocolitica, Salmonella spp., Campylobacter jejuni, and Mycoplasma pneumoniae. Samples of synovial tissue from patients with closed lock and reciprocal clicking were obtained during discectomy and divided into two pieces, the first of which was tested by strand displacement amplification for the presence of C trachomatis, and the second of which was analysed for the presence of species-specific bacterial DNA using 16s rRNA pan-polymerase chain reaction (PCR). There were no significant differences between the groups in the incidence of antibodies against M pneumoniae, Salmonella spp. or Y enterocolitica. No patient had antibodies towards C trachomatis or C jejuni. We found no bacterial DNA in the synovial fluid from any patient. The HLA B27 antigen was present in 2/15 subjects in both the closed lock and control groups, and none in the reciprocal clicking group. In conclusion, reactive arthritis does not seem to be the mechanism of internal derangement of the TMJ.

  18. [Ibopamine--acute hemodynamic, renal and neurohumoral effects].

    PubMed

    Wehling, M; Theisen, K

    1991-01-01

    Ibopamine (IP) is a novel dopamine analogue for which beneficial effects have been shown in chronic heart failure. Hemodynamic effects of the substance include an increase in cardiac output and a decrease in the peripheral resistance. Aside from these hemodynamic effects, changes in renal (increased diuresis) and neurohumoral parameters (decreased plasma renin activity, aldosterone, norepinephrine, increased ANF and cGMP) have been found. The renal effects may originate from three independent mechanisms: 1) direct impact of improved hemodynamic parameters on the renal perfusion; 2) the improved cardiac performance results in a reduction of compensatory hormonal adaptations, such as the activation of the renin-angiotensin-aldosterone-axis or the sympathetic system; 3) direct effects on the intrarenal hemodynamic and glomerular/tubular functions induced by stimulation of renal dopaminergic receptors. The continued decrease of the plasma renin activity by 35% results in a reduction of the plasma levels of angiotensin II and aldosterone. Additionally, an increase in plasma atrial natriuretic factor (ANF) and its second messenger cyclic guanosine monophosphate (cGMP) was observed after ibopamine, which could contribute to the diuretic action of the drug. These findings underline the importance of extrarenal effects of a drug in the treatment of heart failure, this may essentially contribute to the improvement of cardiac performance, independent of positive inotropy.

  19. 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

  20. The Diagnostic Validity of Clinical Tests in Temporomandibular Internal Derangement: A Systematic Review and Meta-analysis.

    PubMed

    Chaput, Eve; Gross, Anita; Stewart, Ryan; Nadeau, Gordon; Goldsmith, Charlie H

    2012-01-01

    Purpose: To assess the diagnostic validity of clinical tests for temporomandibular internal derangement relative to magnetic resonance imaging (MRI). Methods: MEDLINE and Embase were searched from 1994 through 2009. Independent reviewers conducted study selection; risk of bias was assessed using Quality Assessment of studies of Diagnostic Accuracy included in Systematic reviews (QUADAS); ≥9/14) and data abstraction. Overall quality of evidence was profiled using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Agreement was measured using quadratic weighted kappa (κw). Positive (+) or negative (−) likelihood ratios (LR) with 95% CIs were calculated and pooled using the DerSimonian–Laird method and a random-effects model when homogeneous (I(2)≥0.40, Q-test p≤0.10). Results: We selected 8 of 36 studies identified. There is very low quality evidence that deflection (+LR: 6.37 [95% CI, 2.13–19.03]) and crepitation (LR:5.88 [95% CI, 1.95–17.76]) as single tests and crepitation, deflection, pain, and limited mouth opening as a cluster of tests are the most valuable for ruling in internal derangement without reduction (+LR:6.37 [95% CI, 2.13–19.03]), (−LR:0.27 [95% CI, 0.11–0.64]) while the test cluster click, deviation, and pain rules out internal derangement with reduction (−LR: 0.09 [95% CI, 0.01–0.72]). No single test or cluster of tests was conclusive and of significant value for ruling in internal derangement with reduction. Conclusions: Findings of this review will assist clinicians in deciding which diagnostic tests to use when internal derangement is suspected. The literature search revealed a lack of high-quality studies; further research with adequate description of patient populations, blinded assessments, and both sagittal and coronal MRI planes is therefore recommended.

  1. Cerebrovascular hemodynamics during pranayama techniques

    PubMed Central

    Nivethitha, L.; Mooventhan, A.; Manjunath, N. K.; Bathala, Lokesh; Sharma, Vijay K.

    2017-01-01

    Background: Pranayama techniques are known to produce variable physiological effects on the body. We evaluated the effect of the two commonly practiced Pranayama techniques on cerebral hemodynamics. Materials and Methods: Fifteen healthy male volunteers, trained in Yoga and Pranayama, were included in the study. Mean age was 24 years (range 22–32 years). Study participants performed 2 Pranayamas in 2 different orders. Order 1 (n = 7) performed Bhastrika (bellows breaths) followed by Kumbhaka (breath retention) while order 2 (n = 8) performed Kumbhaka followed by Bhastrika. Both breathing techniques were performed for 1 min each. Continuous transcranial Doppler (TCD) monitoring was performed during the breathing techniques. TCD parameters that were recorded included peak systolic velocity (PSV), end-diastolic velocity (EDV), mean flow velocity (MFV), and pulsatility index (PI) of the right middle cerebral artery at baseline, 15, 30, 45, and 60 s. Results: Significant reductions in EDV (3.67 ± 6.48; P < 0.001) and MFV (22.00 ± 7.30; P < 0.001) with a significant increase in PI (2.43 ± 0.76; P < 0.001) were observed during Bhastrika. On the contrary, a significant increase in PSV (65.27 ± 13.75; P < 0.001), EDV (28.67 ± 12.03; P < 0.001), and MFV (43.67 ± 12.85; P < 0.001) with a significant reduction in PI (0.89 ± 0.28; P < 0.01) was observed only during Kumbhaka. Conclusion: Bhastrika and Kumbhaka practices of Pranayama produce considerable and opposing effects on cerebral hemodynamic parameters. Our findings may play a potential role in designing the Pranayama techniques according to patients’ requirements. PMID:28149083

  2. Results of the modified Sauvé-Kapandji procedure in the treatment of chronic posttraumatic derangement of the distal radioulnar joint.

    PubMed

    Lamey, D M; Fernandez, D L

    1998-12-01

    We reviewed the results of a modified Sauvé-Kapandji procedure with tenodesis of the flexor carpi ulnaris to the carpus in eighteen patients who had chronic derangement of the distal radioulnar joint. There were fourteen men and four women. The mean supination of the forearm had improved from 16 degrees (range, 0 to 75 degrees) preoperatively to 76 degrees (range, 40 to 90 degrees) at the time of the latest follow-up, and the mean pronation had improved from 42 degrees (range, 0 to 80 degrees) preoperatively to 81 degrees (range, 60 to 90 degrees) at the time of follow-up. Pain relief was satisfactory, and the mean grip strength had improved from 36 percent of that on the unaffected side preoperatively to 73 percent at the time of follow-up. One patient had moderate pain over the ulnar stump associated with residual volar instability of the proximal ulnar segment, and he had a tenodesis of the extensor carpi ulnaris as a second procedure. Another patient had mild instability of the stump only after he had a second operation, which was an excision of a bone mass (ossification) in the resected area. The ulnar stump was stable in sixteen patients. Eight of the eleven patients who had performed heavy manual labor before the injury were able to return to work full-time without restrictions. According to a modification of the wrist-scoring system of the Mayo Clinic, at a mean of four years and two months (range, two years to eight years and four months), six patients had an excellent result; seven, a good result; four, a fair result; and one, a poor result. On the basis of our findings, we believe that the index operation is an excellent salvage procedure for the treatment of chronic posttraumatic derangement of the distal radioulnar joint, especially when nonoperative treatment has been unsuccessful and rotation of the forearm is severely limited.

  3. Leg vein hemodynamics during bedrests simulating lunar trip.

    PubMed

    Louisy, F; Guezennec, C Y; Güell, A

    1994-05-01

    When contemplating future trips to the Moon whose gravity is one sixth of Earth gravity, the question is to know what the adaptive changes in the lower limb venous system would be. In fact, one can suppose that the presence of a partial gravity on the Moon would be able to attenuate venous hemodynamics adaptative changes observed in microgravity. In the present experiment changes in the venous hemodynamics of lower limbs have been studied with mercury strain gauge plethysmography during a simulated Moon mission including a 4 day trip to the Moon (-6 degrees bedrest), a stay of 6 days on the Moon (+11 degrees bedrest), and a 4-day trip back to Earth (-6 degrees bedrest). It was previously demonstrated that +11 degrees bedrest was a good model to simulate the effects of lunar gravity on the cardiovascular system (Vernikos-Danellis J 1986, personnal communication).

  4. 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.

  5. ADAM10 localization in temporomandibular joint disk with internal derangement: an ex vivo immunohistochemical study.

    PubMed

    Loreto, Carla; Chiarenza, Giovanni Paolo Salvatore; Musumeci, Giuseppe; Castrogiovanni, Paola; Imbesi, Rosa; Ruggeri, Alessandra; Almeida, Luis Edoardo; Leonardi, Rosalia

    2016-04-01

    The purpose of this study was to determine the presence of ADAM10 in temporomandibular joint disk with internal derangement. Twenty-five paraffin blocks of displaced temporomandibular joint (TMJ) disk specimens from earlier investigations were retrieved from the archives of the University of Catania. Of these 16 had been removed from females and 9 from males; 11 with anterior disk displacement with reduction (ADDwR) and 14 with anterior disk displacement without reduction (ADDwoR). The sections were dehydrated, embedded in paraffin and cut. Then they were incubated in 0.3% H2O2/methanol and half of sections from each sample were incubated in diluted rabbit polyclonal anti-ADAM10 antibody. Then biotinylated anti-mouse/anti-rabbit IgG was applied to the sections, followed by avidin-biotin-perioxidase complex. The results were analyzed and the results were that ADAM10 was overexpressed in the posterior band of sections from patients with ADDwR compared to the other bands of both ADDwR and ADDwoR sections. Overexpression correlated with severe histopathological degeneration. We believe these results have the potential to provide insights into the pathogenesis of TMJ disk degeneration and to help design new therapeutic approaches targeting the proteolytic events that lead to tissue degeneration. Early therapeutic block of ADAM10 activity could succeed in limiting aggrecan-rich matrix breakdown without affecting normal physiology.

  6. Diabetes, perioperative ischaemia and volatile anaesthetics: consequences of derangements in myocardial substrate metabolism

    PubMed Central

    2013-01-01

    Volatile anaesthetics exert protective effects on the heart against perioperative ischaemic injury. However, there is growing evidence that these cardioprotective properties are reduced in case of type 2 diabetes mellitus. A strong predictor of postoperative cardiac function is myocardial substrate metabolism. In the type 2 diabetic heart, substrate metabolism is shifted from glucose utilisation to fatty acid oxidation, resulting in metabolic inflexibility and cardiac dysfunction. The ischaemic heart also loses its metabolic flexibility and can switch to glucose or fatty acid oxidation as its preferential state, which may deteriorate cardiac function even further in case of type 2 diabetes mellitus. Recent experimental studies suggest that the cardioprotective properties of volatile anaesthetics partly rely on changing myocardial substrate metabolism. Interventions that target at restoration of metabolic derangements, like lifestyle and pharmacological interventions, may therefore be an interesting candidate to reduce perioperative complications. This review will focus on the current knowledge regarding myocardial substrate metabolism during volatile anaesthesia in the obese and type 2 diabetic heart during perioperative ischaemia. PMID:23452502

  7. Peripheral Disc Margin Shape and Internal Disc Derangement: Imaging Correlation in Significantly Painful Discs Identified at Provocation Lumbar Discography

    PubMed Central

    Bartynski, W.S.; Rothfus, W.E.

    2012-01-01

    Summary Annular margin shape is used to characterize lumbar disc abnormality on CT/MR imaging studies. Abnormal discs also have internal derangement including annular degeneration and radial defects. The purpose of this study was to evaluate potential correlation between disc-margin shape and annular internal derangement on post-discogram CT in significantly painful discs encountered at provocation lumbar discography (PLD). Significantly painful discs were encountered at 126 levels in 86 patients (47 male, 39 female) studied by PLD where no prior surgery had been performed and response to intradiscal lidocaine after provocation resulted in either substantial/total relief or no improvement after lidocaine administration. Post-discogram CT and discogram imaging was evaluated for disc-margin characteristics (bulge/protrusion), features of disc internal derangement (radial annular defect [RD: radial tear/fissure/annular gap], annular degeneration) and presence/absence of discographic contrast leakage. In discs with focal protrusion, 50 of 63 (79%) demonstrated Grade 3 RD with 13 (21%) demonstrating severe degenerative change only. In discs with generalized-bulge-only, 48 of 63 (76%) demonstrated degenerative change only (primarily Dallas Grade 3) with 15 of 63 (24%) demonstrating a RD (Dallas Grade 3). Differences were highly statistically significant (p<0.001). Pain elimination with intra-discal lidocaine correlated with discographic contrast leakage (p<0.001). Disc-margin shape correlates with features of internal derangement in significantly painful discs encountered at PLD. Discs with focal protrusion typically demonstrate RD while generalized bulging discs typically demonstrated degenerative changes only (p<0.001). Disc-margin shape may provide an important imaging clue to the cause of chronic discogenic low back pain. PMID:22681741

  8. Coronary hemodynamic responses during local hemodilution in canine hearts

    SciTech Connect

    Crystal, G.J. )

    1988-03-01

    To evaluate the effect of hemodilution per se on coronary hemodynamics, experiments were performed in 36 anesthetized, open-chest dogs whose left anterior descending coronary artery (LAD) was perfused selectively with either normal arterial blood or arterial blood diluted with lactated Ringer solution. LAD blood flow (CBF) was measured with an electromagnetic flowmeter and its transmural distribution assessed with 15-{mu}m radioactive microspheres. With perfusion pressure normal, graded hemodilution caused progressive, transmurally uniform increases in CBF that showed an nonlinear relationship to inflow hematocrit. Increased peak reactive hyperemic flow and decreased dilator reserve ratio indicated that both reduced viscosity and vasodilation contributed to increased CBF during hemodilution. Hypotension alone reduced CBF, with greater effect in the subendocardium. Additional hemodilution returned CBF to normotensive value, but relative subendocardial hypoperfusion persisted. The present study provides fundamental information on effects of hemodilution on coronary hemodynamics without the systemic responses that complicated previous studies utilizing whole body exchange transfusions.

  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. Influence of population and exercise protocol characteristics on hemodynamic determinants of post-aerobic exercise hypotension.

    PubMed

    Brito, L C; Queiroz, A C C; Forjaz, C L M

    2014-08-01

    Due to differences in study populations and protocols, the hemodynamic determinants of post-aerobic exercise hypotension (PAEH) are controversial. This review analyzed the factors that might influence PAEH hemodynamic determinants, through a search on PubMed using the following key words: "postexercise" or "post-exercise" combined with "hypotension", "blood pressure", "cardiac output", and "peripheral vascular resistance", and "aerobic exercise" combined only with "blood pressure". Forty-seven studies were selected, and the following characteristics were analyzed: age, gender, training status, body mass index status, blood pressure status, exercise intensity, duration and mode (continuous or interval), time of day, and recovery position. Data analysis showed that 1) most postexercise hypotension cases are due to a reduction in systemic vascular resistance; 2) age, body mass index, and blood pressure status influence postexercise hemodynamics, favoring cardiac output decrease in elderly, overweight, and hypertensive subjects; 3) gender and training status do not have an isolated influence; 4) exercise duration, intensity, and mode also do not affect postexercise hemodynamics; 5) time of day might have an influence, but more data are needed; and 6) recovery in the supine position facilitates systemic vascular resistance decrease. In conclusion, many factors may influence postexercise hypotension hemodynamics, and future studies should directly address these specific influences because different combinations may explain the observed variability in postexercise hemodynamic studies.

  11. Cerebral hemodynamics and endothelial function in patients with Fabry disease

    PubMed Central

    2013-01-01

    Background Cerebral vasculopathy have been described in Fabry disease, in which altered cerebral blood flow, vascular remodelling or impairment of endothelial function could be involved. Our study aims to evaluate these three possibilities in a group of Fabry patients, and compare it to healthy controls. Methods Cerebral hemodynamics, vascular remodelling and systemic endothelial function were investigated in 10 Fabry patients and compared to data from 17 healthy controls. Transcranial Doppler was used to study blood flow velocity of intracranial arteries and cerebral vasomotor reactivity. For the study of vascular remodelling and endothelial function, intima-media thickness of common carotid arteries, flow-mediated dilation in brachial artery and serum levels of soluble VCAM-1, TNF-α, high-sensitive CRP and IL-6 were measured. Differences between groups were evaluated using appropriate tests. Results No relevant differences were observed in cerebral hemodynamic parameters, intima-media thickness or flow-mediated dilation. There was a trend for low serum levels of IL-6 and high serum levels of TNF-α and high-sensitive CRP in Fabry patients; plasma concentrations of soluble VCAM-1 were significantly higher in Fabry disease patients than in healthy volunteers (p = 0.02). Conclusions In our sample, we did not find relevant alterations of cerebral hemodynamics in Fabry disease patients. Increased levels of plasmatic endothelial biomarkers seem to be the most important feature indicative of possible vascular dysfunction in Fabry disease patients. PMID:24207059

  12. 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.

  13. Hemodynamic and tubular changes induced by contrast media.

    PubMed

    Caiazza, Antonella; Russo, Luigi; Sabbatini, Massimo; Russo, Domenico

    2014-01-01

    The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI.

  14. The effects of hemodynamic lag on functional connectivity and behavior after stroke.

    PubMed

    Siegel, Joshua S; Snyder, Abraham Z; Ramsey, Lenny; Shulman, Gordon L; Corbetta, Maurizio

    2016-12-01

    Stroke disrupts the brain's vascular supply, not only within but also outside areas of infarction. We investigated temporal delays (lag) in resting state functional magnetic resonance imaging signals in 130 stroke patients scanned two weeks, three months and 12 months post stroke onset. Thirty controls were scanned twice at an interval of three months. Hemodynamic lag was determined using cross-correlation with the global gray matter signal. Behavioral performance in multiple domains was assessed in all patients. Regional cerebral blood flow and carotid patency were assessed in subsets of the cohort using arterial spin labeling and carotid Doppler ultrasonography. Significant hemodynamic lag was observed in 30% of stroke patients sub-acutely. Approximately 10% of patients showed lag at one-year post-stroke. Hemodynamic lag corresponded to gross aberrancy in functional connectivity measures, performance deficits in multiple domains and local and global perfusion deficits. Correcting for lag partially normalized abnormalities in measured functional connectivity. Yet post-stroke FC-behavior relationships in the motor and attention systems persisted even after hemodynamic delays were corrected. Resting state fMRI can reliably identify areas of hemodynamic delay following stroke. Our data reveal that hemodynamic delay is common sub-acutely, alters functional connectivity, and may be of clinical importance.

  15. 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.

  16. Systemic metabolic derangement, pulmonary effects, and insulin insufficiency following subchronic ozone exposure in rats.

    PubMed

    Miller, Desinia B; Snow, Samantha J; Henriquez, Andres; Schladweiler, Mette C; Ledbetter, Allen D; Richards, Judy E; Andrews, Debora L; Kodavanti, Urmila P

    2016-09-01

    Acute ozone exposure induces a classical stress response with elevated circulating stress hormones along with changes in glucose, protein and lipid metabolism in rats, with similar alterations in ozone-exposed humans. These stress-mediated changes over time have been linked to insulin resistance. We hypothesized that acute ozone-induced stress response and metabolic impairment would persist during subchronic episodic exposure and induce peripheral insulin resistance. Male Wistar Kyoto rats were exposed to air or 0.25ppm or 1.00ppm ozone, 5h/day, 3 consecutive days/week (wk) for 13wks. Pulmonary, metabolic, insulin signaling and stress endpoints were determined immediately after 13wk or following a 1wk recovery period (13wk+1wk recovery). We show that episodic ozone exposure is associated with persistent pulmonary injury and inflammation, fasting hyperglycemia, glucose intolerance, as well as, elevated circulating adrenaline and cholesterol when measured at 13wk, however, these responses were largely reversible following a 1wk recovery. Moreover, the increases noted acutely after ozone exposure in non-esterified fatty acids and branched chain amino acid levels were not apparent following a subchronic exposure. Neither peripheral or tissue specific insulin resistance nor increased hepatic gluconeogenesis were present after subchronic ozone exposure. Instead, long-term ozone exposure lowered circulating insulin and severely impaired glucose-stimulated beta-cell insulin secretion. Thus, our findings in young-adult rats provide potential insights into epidemiological studies that show a positive association between ozone exposures and type 1 diabetes. Ozone-induced beta-cell dysfunction may secondarily contribute to other tissue-specific metabolic alterations following chronic exposure due to impaired regulation of glucose, lipid, and protein metabolism.

  17. Systemic Metabolic Derangement, Pulmonary Effects, and Insulin Insufficiency following subchronic ozone exposure in rats

    EPA Science Inventory

    Acute ozone exposure induces a classical stress response with elevated circulating stress hormones along with changes in glucose, protein and lipid metabolism in rats, with similar alterations in ozone-exposed humans. These stress-mediated changes over time have been linked to in...

  18. Exercise Training Prevents Cardiovascular Derangements Induced by Fructose Overload in Developing Rats.

    PubMed

    Farah, Daniela; Nunes, Jonas; Sartori, Michelle; Dias, Danielle da Silva; Sirvente, Raquel; Silva, Maikon B; Fiorino, Patrícia; Morris, Mariana; Llesuy, Susana; Farah, Vera; Irigoyen, Maria-Cláudia; De Angelis, Kátia

    2016-01-01

    The risks of chronic diseases associated with the increasing consumption of fructose-laden foods are amplified by the lack of regular physical activity and have become a serious public health issue worldwide. Moreover, childhood eating habits are strongly related to metabolic syndrome in adults. Thus, we aimed to investigate the preventive role of exercise training undertaken concurrently with a high fructose diet on cardiac function, hemodynamics, cardiovascular autonomic modulation and oxidative stress in male rats after weaning. Male Wistar rats were divided into 4 groups (n = 8/group): Sedentary control (SC), Trained control (TC), Sedentary Fructose (SF) and Trained Fructose (TF). Training was performed on a treadmill (8 weeks, 40-60% of maximum exercise test). Evaluations of cardiac function, hemodynamics, cardiovascular autonomic modulation and oxidative stress in plasma and in left ventricle (LV) were performed. Chronic fructose overload induced glucose intolerance and an increase in white adipose tissue (WAT) weight, in myocardial performance index (MPI) (SF:0.42±0.04 vs. SC:0.24±0.05) and in arterial pressure (SF:122±3 vs. SC:113±1 mmHg) associated with increased cardiac and vascular sympathetic modulation. Fructose also induced unfavorable changes in oxidative stress profile (plasmatic protein oxidation- SF:3.30±0.09 vs. SC:1.45±0.08 nmol/mg prot; and LV total antioxidant capacity (TRAP)- SF: 2.5±0.5 vs. SC:12.7±1.7 uM trolox). The TF group showed reduced WAT, glucose intolerance, MPI (0.35±0.04), arterial pressure (118±2mmHg), sympathetic modulation, plasmatic protein oxidation and increased TRAP when compared to SF group. Therefore, our findings indicate that cardiometabolic dysfunctions induced by fructose overload early in life may be prevented by moderate aerobic exercise training.

  19. Exercise Training Prevents Cardiovascular Derangements Induced by Fructose Overload in Developing Rats

    PubMed Central

    Farah, Daniela; Nunes, Jonas; Sartori, Michelle; Dias, Danielle da Silva; Sirvente, Raquel; Silva, Maikon B.; Fiorino, Patrícia; Morris, Mariana; Llesuy, Susana; Farah, Vera; Irigoyen, Maria-Cláudia; De Angelis, Kátia

    2016-01-01

    The risks of chronic diseases associated with the increasing consumption of fructose-laden foods are amplified by the lack of regular physical activity and have become a serious public health issue worldwide. Moreover, childhood eating habits are strongly related to metabolic syndrome in adults. Thus, we aimed to investigate the preventive role of exercise training undertaken concurrently with a high fructose diet on cardiac function, hemodynamics, cardiovascular autonomic modulation and oxidative stress in male rats after weaning. Male Wistar rats were divided into 4 groups (n = 8/group): Sedentary control (SC), Trained control (TC), Sedentary Fructose (SF) and Trained Fructose (TF). Training was performed on a treadmill (8 weeks, 40–60% of maximum exercise test). Evaluations of cardiac function, hemodynamics, cardiovascular autonomic modulation and oxidative stress in plasma and in left ventricle (LV) were performed. Chronic fructose overload induced glucose intolerance and an increase in white adipose tissue (WAT) weight, in myocardial performance index (MPI) (SF:0.42±0.04 vs. SC:0.24±0.05) and in arterial pressure (SF:122±3 vs. SC:113±1 mmHg) associated with increased cardiac and vascular sympathetic modulation. Fructose also induced unfavorable changes in oxidative stress profile (plasmatic protein oxidation- SF:3.30±0.09 vs. SC:1.45±0.08 nmol/mg prot; and LV total antioxidant capacity (TRAP)- SF: 2.5±0.5 vs. SC:12.7±1.7 uM trolox). The TF group showed reduced WAT, glucose intolerance, MPI (0.35±0.04), arterial pressure (118±2mmHg), sympathetic modulation, plasmatic protein oxidation and increased TRAP when compared to SF group. Therefore, our findings indicate that cardiometabolic dysfunctions induced by fructose overload early in life may be prevented by moderate aerobic exercise training. PMID:27930685

  20. Practical issues of hemodynamic monitoring at the bedside.

    PubMed

    Polanco, Patricio M; Pinsky, Michael R

    2006-12-01

    The hemodynamic monitoring of a surgical patient acquires a major relevance in high-risk patients and those suffering from surgical diseases associated with hemodynamic instability, such as hemorrhagic or septic shock. This article reviews the fundamental physiologic principles needed to understand hemodynamic monitoring at the bedside. Monitoring defines stability, instability, and response to therapy. The major hemodynamic parameters measured and derived from invasive hemodynamic monitoring, such as arterial, central venous, and pulmonary catheterization, are discussed, as are its clinical indications, benefits, and complications. The current clinical data relevant to hemodynamic monitoring are reviewed and discussed.

  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. Diabetes: insulin resistance and derangements in lipid metabolism. Cure through intervention in fat transport and storage.

    PubMed

    Raz, Itamar; Eldor, Roi; Cernea, Simona; Shafrir, Eleazar

    2005-01-01

    We present multiple findings on derangements in lipid metabolism in type 2 diabetes. The increase in the intracellular deposition of triglycerides (TG) in muscles, liver and pancreas in subjects prone to diabetes is well documented and demonstrated to attenuate glucose metabolism by interfering with insulin signaling and insulin secretion. The obesity often associated with type 2 diabetes is mainly central, resulting in the overload of abdominal adipocytes with TG and reducing fat depot capacity to protect other tissues from utilizing a large proportion of dietary fat. In contrast to subcutaneous adipocytes, the central adipocytes exhibit a high rate of basal lipolysis and are highly sensitive to fat mobilizing hormones, but respond poorly to lipolysis restraining insulin. The enlarged visceral adipocytes are flooding the portal circulation with free fatty acids (FFA) at metabolically inappropriate time, when FFA should be oxidized, thus exposing nonadipose tissues to fat excess. This leads to ectopic TG accumulation in muscles, liver and pancreatic beta-cells, resulting in insulin resistance and beta-cell dysfunction. This situation, based on a large number of observations in humans and experimental animals, confirms that peripheral adipose tissue is closely regulated, performing a vital role of buffering fluxes of FFA in the circulation. The central adipose tissues tend to upset this balance by releasing large amounts of FFA. To reduce the excessive fat outflow from the abdominal depots and prevent the ectopic fat deposition it is important to decrease the volume of central fat stores or increase the peripheral fat stores. One possibility is to downregulate the activity of lipoprotein lipase, which is overexpressed in abdominal relatively to subcutaneous fat stores. This can be achieved by gastrointestinal bypass or gastroplasty, which decrease dietary fat absorption, or by direct means that include surgical removal of mesenteric fat. Indirect treatment consists

  3. Verification of a computational cardiovascular system model comparing the hemodynamics of a continuous flow to a synchronous valveless pulsatile flow left ventricular assist device.

    PubMed

    Gohean, Jeffrey R; George, Mitchell J; Pate, Thomas D; Kurusz, Mark; Longoria, Raul G; Smalling, Richard W

    2013-01-01

    The purpose of this investigation is to use a computational model to compare a synchronized valveless pulsatile left ventricular assist device with continuous flow left ventricular assist devices at the same level of device flow, and to verify the model with in vivo porcine data. A dynamic system model of the human cardiovascular system was developed to simulate the support of a healthy or failing native heart from a continuous flow left ventricular assist device or a synchronous pulsatile valveless dual-piston positive displacement pump. These results were compared with measurements made during in vivo porcine experiments. Results from the simulation model and from the in vivo counterpart show that the pulsatile pump provides higher cardiac output, left ventricular unloading, cardiac pulsatility, and aortic valve flow as compared with the continuous flow model at the same level of support. The dynamic system model developed for this investigation can effectively simulate human cardiovascular support by a synchronous pulsatile or continuous flow ventricular assist device.

  4. [Hemodynamic evaluation of the patient with microvarices].

    PubMed

    Alvarez Sánchez, J A; Vega Gómez, M E; Rodríguez Lacaba, B; Martínez Griñán, M A

    1992-01-01

    The present study included 21 lower limbs with micro varicosities, 56 lower limbs with retrograde flow-varicosities (positive Rivlin) and 35 health lower limbs. Technics used for diagnosis were: Doppler ultrasonography and strain gauge plethysmography. We found a higher incidence of valvular failure on the varicose patients with retrograde flow (showing changes on their viscoelastic features of their venous walls). On the contrary, patient with microvaricosities showed an hemodynamics similar to the healty patient: we did not found any difference on the variables analyzed between the two groups. We conclude that the presence of microvaricosities has no influence on the analyzed hemodynamic parametres.

  5. Crucial Role for Neuronal Nitric Oxide Synthase in Early Microcirculatory Derangement and Recipient Survival following Murine Pancreas Transplantation

    PubMed Central

    Cardini, Benno; Watschinger, Katrin; Hermann, Martin; Obrist, Peter; Oberhuber, Rupert; Brandacher, Gerald; Chuaiphichai, Surawee; Channon, Keith M.; Pratschke, Johann; Maglione, Manuel; Werner, Ernst R.

    2014-01-01

    Objective Aim of this study was to identify the nitric oxide synthase (NOS) isoform involved in early microcirculatory derangements following solid organ transplantation. Background Tetrahydrobiopterin donor treatment has been shown to specifically attenuate these derangements following pancreas transplantation, and tetrahydrobiopterin-mediated protective effects to rely on its NOS-cofactor activity, rather than on its antioxidant capacity. However, the NOS-isoform mainly involved in this process has still to be defined. Methods Using a murine pancreas transplantation model, grafts lacking one of the three NOS-isoforms were compared to grafts from wild-type controls. Donors were treated with either tetrahydrobiopterin or remained untreated. All grafts were subjected to 16 h cold ischemia time and transplanted into wild-type recipients. Following 4 h graft reperfusion, microcirculation was analysed by confocal intravital fluorescence microscopy. Recipient survival was monitored for 50 days. Results Transplantation of the pancreas from untreated wild-type donor mice resulted in microcirculatory damage of the transplanted graft and no recipient survived more than 72 h. Transplanting grafts from untreated donor mice lacking either endothelial or inducible NOS led to similar outcomes. In contrast, donor treatment with tetrahydrobiopterin prevented microcirculatory breakdown enabling long-term survival. Sole exception was transplantation of grafts from untreated donor mice lacking neuronal NOS. It resulted in intact microvascular structure and long-term recipient survival, either if donor mice were untreated or treated with tetrahydrobiopterin. Conclusion We demonstrate for the first time the crucial involvement of neuronal NOS in early microcirculatory derangements following solid organ transplantation. In this model, protective effects of tetrahydrobiopterin are mediated by targeting this isoform. PMID:25389974

  6. 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.

  7. Resuscitation of traumatic shock: a hemodynamic review.

    PubMed

    Cottingham, Christine A

    2006-01-01

    Shock, or tissue hypoperfusion, is a frequent complication from traumatic injury. Despite the etiology of the shock state, there is always some component of hypovolemia. The body's innate ability to compensate for impaired perfusion may mask clinical signs, leading to delays in treatment. This article presents an overview of these compensatory mechanisms and resuscitation strategies from the vantage point of routine hemodynamic monitoring.

  8. Renal hemodynamic effects of relaxin in humans.

    PubMed

    Smith, Marie; Davison, John; Conrad, Kirk; Danielson, Lee

    2005-05-01

    Rat studies have convincingly demonstrated the essential role of the ovarian hormone relaxin in mediating gestational renal hemodynamic and osmoregulatory changes in that species. We describe a model in nonpregnant volunteers using exogenous hCG to stimulate the production and release of ovarian relaxin in order to assess renal hemodynamic responses. Women (n = 10) were serially studied +/- hCG stimulation during menstrual cycles with measurement of inulin, PAH, and neutral dextran clearances (to determine glomerular filtration rate [GFR], renal plasma flow [RPF], and glomerular porosity, respectively). Controls were women without ovarian function (n = 6) and men (n = 10). GFR and RPF were increased in the luteal phase compared to the follicular phase (15.3% increase in GFR, P < 0.005; 17.8% increase in RPF, P < 0.05). In controls, GFR and RPF were not significantly different between study occasions. Although exogenous hCG did not stimulate relaxin secretion in women without ovarian function or in men, it did so in normal women, but not into the pregnancy range. In no group were renal hemodynamics augmented by administered hCG. In naturally occurring cycles, increased serum relaxin is associated with augmented renal hemodynamics. As luteal stimulation with hCG failed to yield pregnancy relaxin levels, the use of exogenous relaxin for human administration is needed to further elucidate the renal vasodilatory properties of relaxin.

  9. Very-low-frequency oscillations of cerebral hemodynamics and blood pressure are affected by aging and cognitive load.

    PubMed

    Vermeij, Anouk; Meel-van den Abeelen, Aisha S S; Kessels, Roy P C; van Beek, Arenda H E A; Claassen, Jurgen A H R

    2014-01-15

    Spontaneous slow oscillations occur in cerebral hemodynamics and blood pressure (BP), and may reflect neurogenic, metabolic or myogenic control of the cerebral vasculature. Aging is accompanied by a degeneration of the vascular system, which may have consequences for regional cerebral blood flow and cognitive performance. This degeneration may be reflected in a reduction of spontaneous slow oscillations of cerebral hemodynamics and BP. Therefore, we aimed to establish the dependency of slow oscillations of cerebral hemodynamics and BP on the factors age and cognitive load, by using functional near-infrared spectroscopy (fNIRS). Fourteen healthy young (23-32 years) and 14 healthy older adults (64-78 years) performed a verbal n-back working-memory task. Oxygenated and deoxygenated hemoglobin concentration changes were registered by two fNIRS channels located over left and right prefrontal cortex. BP was measured in the finger by photoplethysmography. We found that very-low-frequency oscillations (0.02-0.07 Hz) and low-frequency oscillations (0.07-0.2 Hz) of cerebral hemodynamics and BP were reduced in the older adults compared to the young during task performance. In young adults, very-low-frequency oscillations of cerebral hemodynamics and BP reduced with increased cognitive load. Cognitive load did not affect low-frequency oscillations of the cerebral hemodynamics and BP. Transfer function analysis indicated that the relationship between BP and cerebral hemodynamic oscillations does not change under influence of age and cognitive load. Our results suggest aging-related changes in the microvasculature such as declined spontaneous activity in microvascular smooth muscle cells and vessel stiffness. Moreover, our results indicate that in addition to local vasoregulatory processes, systemic processes also influence cerebral hemodynamic signals. It is therefore crucial to take the factors age and BP into consideration for the analysis and interpretation of hemodynamic

  10. 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.

  11. Portal hypertension: angiographic and hemodynamic evaluation.

    PubMed

    Koolpe, H A; Koolpe, L

    1986-09-01

    There has been a correlation of three hemodynamic parameters with the etiology of portal hypertension and one of the major determinants of therapeutic success, namely, the direction of portal flow. The presence of a 4 mm Hg or greater gradient between the right atrium and the intrahepatic inferior vena cava associated with a "lumpy" pull-back tracing between the wedged and free positions has been associated with alcoholic liver disease. Such patients have antegrade portal flow when their AoD/HWP ratio is in the range of 2.6 to 2.0, and flow becomes stagnant or reversed below this range. Nonalcoholic liver disease is characterized by the absence of a gradient between the right atrium and the inferior vena cava and by a pull-back tracing that falls smoothly and rapidly to the free hepatic vein value. These patients have antegrade portal flow with an AoD/HWP ratio in the range of 1.7 to 1.5. The correct characterization of the cause for diffuse liver disease and direction of portal flow applies to the selection process for patients being considered for the selective distal splenorenal shunt as well as for the newer procedure of orthotopic liver transplantation. It is hoped that the wider application of these physiologic parameters, in the context of an increasing array of imaging tools for the portal system, including high-resolution ultrasound, computed tomography, and magnetic resonance imaging (MRI), will continue to offer all clinicians interested in the problem of portal hypertension a reliable guide to prognosis and the success of the particular treatment provided.

  12. 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

  13. Clitoral hemodynamic changes after a topical application of alprostadil.

    PubMed

    Becher, E F; Bechara, A; Casabe, A

    2001-01-01

    We performed duplex ultrasonography of the clitoris to assess the local hemodynamic changes after a topical application of alprostadil. Color duplex ultrasonography was used to evaluate 18 women before and after the application of 1 g of 0.2% alprostadil gel. The peak systolic velocity and end diastolic velocity showed a statistically significant difference after the application. All women showed labial and clitoral engorgement, 72% reported a pleasant sensation of warmth, and no systemic side effects were found. These findings are similar to the values reported after sexual stimulation, indicating that topical vasoactive drugs might help in the differential diagnosis of the vascular component of female sexual dysfunction.

  14. Amelioration of pancreatic and renal derangements in streptozotocin-induced diabetic rats by polyphenol extracts of Ginger (Zingiber officinale) rhizome.

    PubMed

    Kazeem, Mutiu Idowu; Akanji, Musbau Adewunmi; Yakubu, Musa Toyin

    2015-12-01

    Free and bound polyphenol extracts of Zingiber officinale rhizome were investigated for their antidiabetic potential in the pancreatic and renal tissues of diabetic rats at a dose of 500mg/kg body weight. Forty Wistar rats were completely randomized into five groups: A-E consisting of eight animals each. Group A (control) comprises normal healthy animals and were orally administered 1.0mL distilled water on a daily basis for 42 days while group B-E were made up of 50mg/kg streptozotocin (STZ)-induced diabetic rats. Group C and D received 1.0mL 500mg/kg body weight free and bound polyphenol extracts respectively while group E received 1.0mL 0.6mg/kg of glibenclamide. Administration of the extracts to the diabetic rats significantly reduced (p<0.05) serum glucose and urea concentrations, increased (p<0.05) serum insulin and Homeostatic Model Assessment for β-cell dysfunction (HOMA-β) while the level of creatinine and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) were not affected. Histological examination of the pancreas and kidney revealed restoration of the structural derangements caused by streptozotocin in the polyphenol extracts treated diabetic rats compared to the control groups. Therefore, polyphenols from Zingiber officinale could ameliorate diabetes-induced pancreatic and renal derangements in rats.

  15. Donizetti and the music of mental derangement: Anna Bolena, Lucia di Lammermoor, and the composer's neurobiological illness.

    PubMed Central

    Peschel, E.; Peschel, R.

    1992-01-01

    The composer Gaetano Donizetti, who died in a state of mental derangement due to neurosyphilis, created some of opera's greatest scenes of psychosis. His letters reveal the clinical progression of his neurobiological illness, which was confirmed by autopsy. One can hypothesize that the composer's brain disease, which led to his psychosis and death, may have had an influence on his ability to create the powerful and unforgettable scenes of psychosis in his operas. In Anna Bolena, he captured in musical and dramatic terms Anne Boleyn's historically corroborated mental disorder during her imprisonment in the Tower of London. Sixteen years after having composed Anna Bolena, Donizetti himself would be locked up, against his will, in a mental institution. In Lucia di Lammermoor, Donizetti portrayed a girl given to hallucinations who, in her unforgettable "mad" scene, comes on stage, a pathetic embodiment of a human being in the throes of psychosis. Thirteen years after Lucia's première, Donizetti would die, psychotic and paralyzed, of untreated neurosyphilis. Studying Donizetti's neurosyphilis and the portrayals of psychosis in his operas can help one to appreciate the pain of human beings trapped in the prison of a brain subjected to the devastation of mental derangement. PMID:1285447

  16. 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).

  17. Characterization of the spectrum of hemodynamic profiles in trauma patients with acute neurogenic shock☆

    PubMed Central

    Summers, Richard L.; Baker, Stephen D.; Sterling, Sarah A.; Porter, John M; Jones, Alan E.

    2014-01-01

    Objective Neurogenic shock considered a distributive type of shock secondary to loss of sympathetic outflow to the peripheral vasculature. In this study, we examine the hemodynamic profiles of a series of trauma patients with a diagnosis of neurogenic shock. Methods Hemodynamic data were collected on a series of trauma patients determined to have spinal cord injuries with neurogenic shock. A well-established integrated computer model of human physiology was used to analyze and categorize the hemodynamic profiles from a system analysis perspective. A differentiation between these categories was presented as the percent of total patients. Results Of the 9 patients with traumatic neurogenic shock, the etiology of shock was decrease in peripheral vascular resistance (PVR) in 3 (33%; 95% confidence interval, 12%–65%), loss of vascular capacitance in 2 (22%; 6%–55%) and mixed peripheral resistance and capacitance responsible in 3 (33%; 12%–65%), and purely cardiac in 1 (11%; 3%–48%). The markers of sympathetic outflow had no correlation to any of the elements in the patients' hemodynamic profiles. Conclusions Results from this study suggest that hypotension of neurogenic shock can have multiple mechanistic etiologies and represents a spectrum of hemodynamic profiles. This understanding is important for the treatment decisions in managing these patients. PMID:23566731

  18. Current and Potential Therapeutic Strategies for Hemodynamic Cardiorenal Syndrome

    PubMed Central

    Obi, Yoshitsugu; Kim, Taehee; Kovesdy, Csaba P.; Amin, Alpesh N.; Kalantar-Zadeh, Kamyar

    2016-01-01

    Background Cardiorenal syndrome (CRS) encompasses conditions in which cardiac and renal disorders co-exist and are pathophysiologically related. The newest classification of CRS into seven etiologically and clinically distinct types for direct patient management purposes includes hemodynamic, uremic, vascular, neurohumoral, anemia- and/or iron metabolism-related, mineral metabolism-related and protein-energy wasting-related CRS. This classification also emphasizes the pathophysiologic pathways. The leading CRS category remains hemodynamic CRS, which is the most commonly encountered type in patient care settings and in which acute or chronic heart failure leads to renal impairment. Summary This review focuses on selected therapeutic strategies for the clinical management of hemodynamic CRS. This is often characterized by an exceptionally high ratio of serum urea to creatinine concentrations. Loop diuretics, positive inotropic agents including dopamine and dobutamine, vasopressin antagonists including vasopressin receptor antagonists such as tolvaptan, nesiritide and angiotensin-neprilysin inhibitors are among the pharmacologic agents used. Additional therapies include ultrafiltration (UF) via hemofiltration or dialysis. The beneficial versus unfavorable effects of these therapies on cardiac decongestion versus renal blood flow may act in opposite directions. Some of the most interesting options for the outpatient setting that deserve revisiting include portable continuous dobutamine infusion, peritoneal dialysis and outpatient UF via hemodialysis or hemofiltration. Key Messages The new clinically oriented CRS classification system is helpful in identifying therapeutic targets and offers a systematic approach to an optimal management algorithm with better understanding of etiologies. Most interventions including UF have not shown a favorable impact on outcomes. Outpatient portable dobutamine infusion is underutilized and not well studied. Revisiting traditional and

  19. 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.

  20. Hemodynamics of physiological blood flow in the aorta with nonlinear anisotropic heart valve

    NASA Astrophysics Data System (ADS)

    Sotiropoulos, Fotis; Gilmanov, Anvar; Stolarski, Henryk

    2016-11-01

    The hemodynamic blood flow in cardiovascular system is one of the most important factor, which causing several vascular diseases. We developed a new Curvilinear Immersed Boundary - Finite Element - Fluid Structure Interaction (CURVIB-FE-FSI) method to analyze hemodynamic of pulsatile blood flow in a real aorta with nonlinear anisotropic aortic valve at physiological conditions. Hyperelastic material model, which is more realistic for describing heart valve have been incorporated in the CURVIB-FE-FSI code to simulate interaction of aortic heart valve with pulsatile blood flow. Comparative studies of hemodynamics for linear and nonlinear models of heart valve show drastic differences in blood flow patterns and hence differences of stresses causing impact at leaflets and aortic wall. This work is supported by the Lillehei Heart Institute at the University of Minnesota.

  1. Hemodynamics: Biophysics for AP Biology

    ERIC Educational Resources Information Center

    Neulieb, Marilyn Huetten; Neulieb, Robert

    1975-01-01

    Discusses the physics of fluids flowing through vessels in the context of blood moving in the circulatory system. The method of presentation used is judged suitable for students in an advanced high school science course emphasizing individualized instruction in an interdisciplinary field. (Author/PEB)

  2. [Relationship between the mandibular hypoplasia and temporomandibular joint internal derangement in adolescents with skeletal class Ⅱ malocclusion].

    PubMed

    Fang, B

    2017-03-09

    Mandibular hypoplasia is very common clinically. Studies have reported that temporomandibular joint internal derangement (TMJID) might manifest as mandibular retrusion, and whether there is a direct correlation between them remains controversial in academia. On the other hand, for adolescent patients with skeletal class Ⅱ malocclusion, the growth of mandible could be motivated by orthopedic force, and then the mandibular retrusion corrected. However, if TMJID is the direct cause of mandibular retrusion, orthopedic treatment will not have a significant effect on it. Base on literature review and analysis as well as our own research, this article will review the distribution of structural abnormalities of the temporomandibular joint in adolescents with mandibular hypoplasia and its association with skeletal class Ⅱ malocclusion, as well as the effect of TMJID on the treatment of skeletal class Ⅱ malocclusion in adolescents.

  3. A Derangement of the Brain Wound Healing Process May Cause Some Cases of Alzheimer’s Disease

    PubMed Central

    Lehrer, Steven; Rheinstein, Peter H.

    2016-01-01

    A derangement of brain wound healing may cause some cases of Alzheimer’s disease. Wound healing, a highly complex process, has four stages: hemostasis, inflammation, repair, and remodeling. Hemostasis and the initial phases of inflammation in brain tissue are typical of all vascularized tissue, such as skin. However, distinct differences arise in brain tissue during the later stages of inflammation, repair, and remodeling, and closely parallel the changes of Alzheimer’s disease. Our hypothesis – Alzheimer’s disease is brain wound healing gone awry at least in some cases – could be tested by measuring progression with biomarkers for the four stages of wound healing in humans or appropriate animal models. Autopsy studies might be done. Chronic traumatic encephalopathy might also result from the brain wound healing process. PMID:27585229

  4. Renal Hemodynamics in AKI: In Search of New Treatment Targets.

    PubMed

    Matejovic, Martin; Ince, Can; Chawla, Lakhmir S; Blantz, Roland; Molitoris, Bruce A; Rosner, Mitchell H; Okusa, Mark D; Kellum, John A; Ronco, Claudio

    2016-01-01

    Novel therapeutic interventions are required to prevent or treat AKI. To expedite progress in this regard, a consensus conference held by the Acute Dialysis Quality Initiative was convened in April of 2014 to develop recommendations for research priorities and future directions. Here, we highlight the concepts related to renal hemodynamics in AKI that are likely to reveal new treatment targets on investigation. Overall, we must better understand the interactions between systemic, total renal, and glomerular hemodynamics, including the role of tubuloglomerular feedback. Furthermore, the net consequences of therapeutic maneuvers aimed at restoring glomerular filtration need to be examined in relation to the nature, magnitude, and duration of the insult. Additionally, microvascular blood flow heterogeneity in AKI is now recognized as a common occurrence; timely interventions to preserve the renal microcirculatory flow may interrupt the downward spiral of injury toward progressive kidney failure and should, therefore, be investigated. Finally, development of techniques that permit an integrative physiologic approach, including direct visualization of renal microvasculature and measurement of oxygen kinetics and mitochondrial function in intact tissue in all nephron segments, may provide new insights into how the kidney responds to various injurious stimuli and allow evaluation of new therapeutic strategies.

  5. [Hemodynamic Status of Prepubertal and Pubertal Hockey Players].

    PubMed

    Shayhelislamova, M V; Sitdikov, F G; Zefirov, T L; Dikopolskaya, N B

    2015-01-01

    The hemodynamic status of 11-15-year-old hockey players depending on their age and puberty stage were studied and compared with hemodynamic parameters of the control group. It was found that regular muscle training has a dominant effect on the functional state of cardiovascular system (CVS) in prepuberty and puberty. It was proved that in hockey players a decrease in the heart rate (H R) and an increase in the stroke volume (SV) result in a significant increase in systolic blood pressure (SBP) at the age of 11-14 years and a progressive increase in total peripheral vascular resistance (PVR), in contrast to significantly lower values in the control group. The urgent adaptation of CVS to graduated physical activities at the age of 11-13 years leads to an enhancement of vascular spasmodic reactions while SV remains constant. It was found that in adolescent hockey players have consistently high SV and SBP; at the same time, maximal values of HR, cardiac output (CO) and diastolic blood pressure (DBP) were observed at the stages I and II of the puberty period; then, at the stage III, these parameters decrease. I n the control group, hymodinamic status changed in an opposite way. This may be an evidence of the stress effect of physical activities which results in the adaptive reactions of CVS rather than reactions typical of the puberty period.

  6. 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.

  7. 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.

  8. Hemodynamic Changes following Aortic Valve Bypass: A Mathematical Approach

    PubMed Central

    Benevento, Emilia; Djebbari, Abdelghani; Keshavarz-Motamed, Zahra; Cecere, Renzo; Kadem, Lyes

    2015-01-01

    Aortic valve bypass (AVB) has been shown to be a viable solution for patients with severe aortic stenosis (AS). Under this circumstance, the left ventricle (LV) has a double outlet. The objective was to develop a mathematical model capable of evaluating the hemodynamic performance following the AVB surgery. A mathematical model that captures the interaction between LV, AS, arterial system, and AVB was developed. This model uses a limited number of parameters that all can be non-invasively measured using patient data. The model was validated using in vivo data from the literature. The model was used to determine the effect of different AVB and AS configurations on flow proportion and pressure of the aortic valve and the AVB. Results showed that the AVB leads to a significant reduction in transvalvular pressure gradient. The percentage of flow through the AVB can range from 55.47% to 69.43% following AVB with a severe AS. LV stroke work was also significantly reduced following the AVB surgery and reached a value of around 1.2 J for several AS severities. Findings of this study suggest: 1) the AVB leads to a significant reduction in transvalvular pressure gradients; 2) flow distribution between the AS and the AVB is significantly affected by the conduit valve size; 3) the AVB leads to a significant reduction in LV stroke work; and 4) hemodynamic performance variations can be estimated using the model. PMID:25881082

  9. Renal Hemodynamics in AKI: In Search of New Treatment Targets

    PubMed Central

    Matejovic, Martin; Ince, Can; Chawla, Lakhmir S.; Blantz, Roland; Molitoris, Bruce A.; Okusa, Mark D.; Kellum, John A.; Ronco, Claudio

    2016-01-01

    Novel therapeutic interventions are required to prevent or treat AKI. To expedite progress in this regard, a consensus conference held by the Acute Dialysis Quality Initiative was convened in April of 2014 to develop recommendations for research priorities and future directions. Here, we highlight the concepts related to renal hemodynamics in AKI that are likely to reveal new treatment targets on investigation. Overall, we must better understand the interactions between systemic, total renal, and glomerular hemodynamics, including the role of tubuloglomerular feedback. Furthermore, the net consequences of therapeutic maneuvers aimed at restoring glomerular filtration need to be examined in relation to the nature, magnitude, and duration of the insult. Additionally, microvascular blood flow heterogeneity in AKI is now recognized as a common occurrence; timely interventions to preserve the renal microcirculatory flow may interrupt the downward spiral of injury toward progressive kidney failure and should, therefore, be investigated. Finally, development of techniques that permit an integrative physiologic approach, including direct visualization of renal microvasculature and measurement of oxygen kinetics and mitochondrial function in intact tissue in all nephron segments, may provide new insights into how the kidney responds to various injurious stimuli and allow evaluation of new therapeutic strategies. PMID:26510884

  10. [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.

  11. Patient-Specific Modeling of Interventricular Hemodynamics in Single Ventricle Physiology

    NASA Astrophysics Data System (ADS)

    Vedula, Vijay; Feinstein, Jeffrey; Marsden, Alison

    2016-11-01

    Single ventricle (SV) congenital heart defects, in which babies are born with only functional ventricle, lead to significant morbidity and mortality with over 30% of patients developing heart failure prior to adulthood. Newborns with SV physiology typically undergo three palliative surgeries, in which the SV becomes the systemic pumping chamber. Depending on which ventricle performs the systemic function, patients are classified as having either a single left ventricle (SLV) or a single right ventricle (SRV), with SRV patients at higher risk of failure. As the native right ventricles are not designed to meet systemic demands, they undergo remodeling leading to abnormal hemodynamics. The hemodynamic characteristics of SLVs compared with SRVs is not well established. We present a validated computational framework for performing patient-specific modeling of ventricular flows, and apply it across 6 SV patients (3SLV + 3SRV), comparing hemodynamic conditions between the two subgroups. Simulations are performed with a stabilized finite element method coupled with an immersed boundary method for modeling heart valves. We discuss identification of hemodynamic biomarkers of ventricular remodeling for early risk assessment of failure. This research is supported in part by the Stanford Child Health Research Institute and the Stanford NIH-NCATS-CTSA through Grant UL1 TR001085 and due to U.S. National Institute of Health through NIH NHLBI R01 Grants 5R01HL129727-02 and 5R01HL121754-03.

  12. 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.

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

    PubMed

    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-Tc 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.

  14. Hemodynamic response to the upright posture.

    PubMed

    Smith, J J; Porth, C M; Erickson, M

    1994-05-01

    The authors' objective was to review previous studies of immediate (first 30 seconds) and stabilized (30 seconds to 20 minutes) hemodynamic responses of healthy adults to the head-up posture, with particular reference to alteration of such responses in the elderly and the usefulness of such data in the diagnosis of orthostatic hypotension. The immediate response in healthy young adults is characterized by a prompt rise in heart rate, which peaks at about 8 to 15 seconds and then tapers; the arterial pressure and total vascular resistance decrease sharply at 5 to 10 seconds, followed by a rapid rebound and overshoot. Over the first 30 seconds there is a steady parallel decline of thoracic blood volume and stroke volume; there is also an initial surge of cardiac output followed by a steady decrease. During the stabilized response (30 seconds to 20 minutes), the hemodynamic variables are relatively steady, showing average increases in heart rate of about 15 to 30%, in diastolic pressure of 10 to 15%, and in total vascular resistance of 30 to 40%; during the 5th to 20th minutes there are also decreases in thoracic blood volume averaging about 25 to 30%, in cardiac output 15 to 30%, and in pulse pressure about 5 to 10%. It is evident that in normal human subjects, assumption of the upright posture results in profound hemodynamic changes, most of them occurring during the first 30 seconds. In elderly subjects (aged 60-69 years), there are, in the upright posture, lesser increments of heart rate and diastolic pressure, but no significant differences from younger age groups in the response of thoracic blood volume, cardiac output or total vascular resistance. However, beginning at about age 75, there is an increasing incidence of orthostatic hypotension, which averages about 14 to 20% at age 75 and older. The tendency toward orthostatic hypotension in the elderly is due (1) to the structural and functional changes in the circulation itself, (2) to a decline in autonomic

  15. 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

  16. Sildenafil Exposure and Hemodynamic Effect after Fontan Surgery

    PubMed Central

    Tunks, Robert D.; Barker, Piers C. A.; Benjamin, Daniel K.; Cohen-Wolkowiez, Michael; Fleming, Gregory A.; Laughon, Matthew; Li, Jennifer S.; Hill, Kevin D.

    2013-01-01

    Objective Determine sildenafil exposure and hemodynamic effect in children after Fontan single-ventricle surgery. Design Prospective, dose-escalation trial. Setting Single-center, pediatric catheterization laboratory. Patients 9 children post Fontan single-ventricle surgical palliation and undergoing elective cardiac catheterization: Median (range) age and weight: 5.2 years (2.5–9.4) and 16.3 kg (9.5–28.1). Five children (55%) were male, and 6/9 (67%) had a systemic right ventricle. Interventions Catheterization and echocardiography performed before and immediately after single-dose intravenous sildenafil (0.25, 0.35, or 0.45 mg/kg over 20 minutes). Measurements Peak sildenafil and des-methyl sildenafil concentration, change in hemodynamic parameters measured by cardiac catheterization and echocardiography. Main Results Maximum sildenafil concentrations ranged from 124–646 ng/ml and were above the in vitro threshold needed for 77% phosphodiesterase type-5 (PDE-5) inhibition in 8/9 children and 90% inhibition in 7/7 of children with doses ≥0.35 mg/kg. Sildenafil improved stroke volume (+22%, p=0.05) and cardiac output (+10%, p=0.01) with no significant change in heart rate in 8/9 children. Sildenafil also lowered systemic (-16%, p=0.01) and pulmonary vascular resistance index (PVRI) in all 9 children (median baseline PVRI 2.4 [range: 1.3, 3.7]; decreased to 1.9 [0.8, 2.7] WU x m2; p=0.01) with no dose-response effect. Pulmonary arterial pressures decreased (−10%, p=0.02) and pulmonary blood flow increased (9%, p=0.02). There was no change in myocardial performance index and no adverse events. Conclusions After Fontan surgery, sildenafil infusion acutely improves cardiopulmonary hemodynamics, increasing cardiac index. For the range of doses studied, exposure was within the acute safety range reported in adult subjects. PMID:24201857

  17. 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.

  18. Hemodynamic forces in a model left ventricle

    NASA Astrophysics Data System (ADS)

    Domenichini, Federico; Pedrizzetti, Gianni

    2016-12-01

    Intraventricular pressure gradients were clinically demonstrated to represent one useful indicator of the left ventricle (LV) function during the development of heart failure. We analyze the fluid dynamics inside a model LV to improve the understanding of the development of hemodynamic forces (i.e., mean pressure gradient) in normal conditions and their modification in the presence of alterations of LV tissue motion. To this aim, the problem is solved numerically and the global force exchanged between blood flow and LV boundaries is computed by volume integration. We also introduce a simplified analytical model, based on global conservation laws, to estimate hemodynamic forces from the knowledge of LV tissue information commonly available in cardiac imaging. Numerical results show that the normal intraventricular gradients feature a deep brief suction at early diastolic filling and a persistent thrust during systolic ejection. In presence of abnormalities of the wall motion, the loss of time synchrony is more relevant than the loss of spatial uniformity in modifying the normal pressure gradient spatiotemporal pattern. The main findings are reproduced in the integral model, which represents a possible easy approach for integrating fluid dynamics evaluations in the clinical examination.

  19. Calpain Protects the Heart from Hemodynamic Stress*

    PubMed Central

    Taneike, Manabu; Mizote, Isamu; Morita, Takashi; Watanabe, Tetsuya; Hikoso, Shungo; Yamaguchi, Osamu; Takeda, Toshihiro; Oka, Takafumi; Tamai, Takahito; Oyabu, Jota; Murakawa, Tomokazu; Nakayama, Hiroyuki; Nishida, Kazuhiko; Takeda, Junji; Mochizuki, Naoki; Komuro, Issei; Otsu, Kinya

    2011-01-01

    Calpains make up a family of Ca2+-dependent intracellular cysteine proteases that include ubiquitously expressed μ- and m-calpains. Both are heterodimers consisting of a distinct large catalytic subunit (calpain 1 for μ-calpain and calpain 2 for m-calpain) and a common regulatory subunit (calpain 4). The physiological roles of calpain remain unclear in the organs, including the heart, but it has been suggested that calpain is activated by Ca2+ overload in diseased hearts, resulting in cardiac dysfunction. In this study, cardiac-specific calpain 4-deficient mice were generated to elucidate the role of calpain in the heart in response to hemodynamic stress. Cardiac-specific deletion of calpain 4 resulted in decreased protein levels of calpains 1 and 2 and showed no cardiac phenotypes under base-line conditions but caused left ventricle dilatation, contractile dysfunction, and heart failure with interstitial fibrosis 1 week after pressure overload. Pressure-overloaded calpain 4-deficient hearts took up a membrane-impermeant dye, Evans blue, indicating plasma membrane disruption. Membrane repair assays using a two-photon laser-scanning microscope revealed that calpain 4-deficient cardiomyocytes failed to reseal a plasma membrane that had been disrupted by laser irradiation. Thus, the data indicate that calpain protects the heart from hemodynamic stresses, such as pressure overload. PMID:21795695

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Hemodynamic Analysis of Pediatric Septic Shock and Cardiogenic Shock Using Transpulmonary Thermodilution

    PubMed Central

    Lee, En-Pei; Hsia, Shao-Hsuan; Lin, Jainn-Jim; Chan, Oi-Wa; Lee, Jung; Lin, Chia-Ying

    2017-01-01

    Septic shock and cardiogenic shock are the two most common types of shock in children admitted to pediatric intensive care units (PICUs). The aim of the study was to investigate which hemodynamic variables were associated with mortality in children with shock. We retrospectively analyzed 50 children with shock (37 septic shock cases and 13 cardiogenic shock cases) in the PICU and monitored their hemodynamics using transpulmonary thermodilution from 2003 to 2016. Clinical factors were analyzed between the patients with septic and cardiogenic shock. In addition, hemodynamic parameters associated with mortality were analyzed. The 28-day mortality was significantly higher in the septic group than in the cardiogenic group (p = 0.016). Initially, the parameters of cardiac output and cardiac contractility were higher in the septic group (p < 0.05) while the parameters of preload and afterload were all higher in the cardiogenic group (p < 0.05). Cardiac index was significantly lower in the nonsurvivors of cardiogenic shock at the time of initial admission and after the first 24 hours (both p < 0.05), while systemic vascular resistance index (SVRI) was significantly lower in the nonsurvivors of septic shock (p < 0.001). Therefore, during the first 24 hours after intensive care, SVRI and cardiac index are the most important hemodynamic parameters associated with mortality.

  5. 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

  6. [The changes of hemodynamic parameters, pathology and c-kit mRNA expression in myocardium after acute myocardial infarction in rats].

    PubMed

    Chen, Shiqian; Long, Weifu; Wu, Wenchao; Jiang, Congxun; Liu, Xiaojing; Li, Liang

    2009-06-01

    This study was aimed to investigate the changes of hemodynamic parameters, pathology and c kit mRNA expression in myocardium after acute myocardial infarctionin (AMI) in rats, and to elucidate the relationship between these three kinds of changes. Sixty six adult male SD rats were randomly divided into normal group, Sham groups and ligation groups. The rat model of AMI was set up by ligating the left anterior descending artery. Hemodynamic parameters, pathological changes and c kit mRNA expression in myocardiam were examined. The results revealed that there were no statistically significant differences in hemodynamic parameters between normal group and Sham groups. Compared with the normal group, all ligation groups exhibited significantly decreased left ventricular systolic pressure (LVSP) and +/-dp/dtmax (P<0.01), and increased left ventricular end diastolic pressure (LVEDP, P<0.01). In the other ligation groups, compared with 6th hour group after ligation, there appeared striking increase of LVSP, LVEDP and +/-dp/dtmax (P<0.05). HE staining in myocardiam showed that there are necrosis and derangement at 24th hour group after ligation ,and a great number of inflammatory cells infiltration around the infarct zone at 3rd day group after ligation, and granulation tissue infiltrated into the infarct zone at 14th day group after ligation. In all five time points groups after ligation, the levels of c-kit mRNA expression were 0.99 fold, 1.06 fold, 1.46 fold, 1.91 fold and 2.67 fold, respectively, compared with Sham groups. The results suggest that cardiac stem cells in myocardium might contribute to the role of regenerating myocardium via self proliferation after acute myocardial infarction, but further investigation is still needed.

  7. A cross-sectional study of the relationship between serum sexual hormone levels and internal derangement of temporomandibular joint.

    PubMed

    Madani, A S; Shamsian, A A; Hedayati-Moghaddam, M R; Fathi-Moghadam, F; Sabooni, M R; Mirmortazavi, A; Golmohamadi, M

    2013-08-01

    Temporomandibular disorders (TMD) are defined as clinical conditions that involve the masticatory muscles, temporomandibular joint (TMJ) or both. The aim of this study was to evaluate serum 17β-oestradiol and progesterone levels in menstruating women affected by internal derangement of the TMJ. A total of 142 women (mean age 30·2 ± 6·7) who referred to medical diagnostic laboratory of Iranian Academic Centre for Education, Culture and Research (ACECR), Mashhad Branch, were enrolled during 2007 and 2008. Forty-seven individuals had disc displacement with reduction (Group IIa) according to Research Diagnostic Criteria (RDC)/TMD Axis I diagnosis. Radioimmunoassay was used for the detection of serum 17β-oestradiol and progesterone levels in all 142 subjects. The mean progesterone level was significantly higher in control group (11·6 ± 10·4 ng mL(-1) ) compared to women with TMD (8·4 ± 6·8 ng mL(-1) , P = 0·03). No significant difference was found in two groups regarding 17β-oestradiol level. Lower progesterone level in women with TMD can suggest the more important role of this hormone in the development of the disorder.

  8. An Ex Vivo Study on Immunohistochemical Localization of MMP-7 and MMP-9 in Temporomandibular Joint Discs with Internal Derangement

    PubMed Central

    Loreto, C.; Leonardi, R.; Musumeci, G.; Pannone, G.; Castorina, S.

    2013-01-01

    Internal derangement (ID) is among the most common disorders of the temporomandibular joint (TMJ). Previous research by our group highlighted a correlation between apoptosis and TMJ ID. Metalloproteinases (MMP)-7 and -9 have been shown to play an important role in extracellular matrix ECM) homeostasis and, through it, in joint disc remodelling. The immunohistochemical expression of MMP-7 and -9 was investigated in discs from patients with TMJ ID and from healthy donors and compared with the degree of histological tissue degeneration. The collagen fibre arrangement in pathological discs exhibited varying degrees of disruption. New vessels were consistently detected; endothelial cells from these vessels were immunolabelled with both MMP-7 and MMP-9. More or less intense MMP-7 and MMP-9 immunolabelling was detected in the cytoplasm of disc cells from all patients. MMP-7 and MMP-9 immunostaining was significantly different between pathological and normal discs and correlated with the extent of histopathological degeneration. MMP-7 and MMP-9 upregulation in discs from patients with TMJ ID demonstrates their involvement in disc damage in this disorder. A greater understanding of these processes could help identify ways to curb MMP overproduction without affecting their tissue remodelling action. The design of specific inhibitors for these MMPs would not only help to gain insights into the biological roles of MMPs, but would also aid in developing therapeutic interventions for diseases associated with abnormal ECM degradation. PMID:23807291

  9. Continuous Noninvasive Hemodynamic Monitoring in an Infant With Tetra-Amelia.

    PubMed

    Vadi, Marissa G; Ghazal, Elizabeth A; Malkin, Mathew R; Ayodeji, Abisola; Applegate, Richard L

    2016-09-15

    Tetra-amelia syndrome is a congenital disorder associated with near or complete absence of all 4 limbs. Noninvasive hemodynamic monitoring may be difficult or impossible in such patients. We describe the use of a finger cuff blood pressure system for continuous noninvasive blood pressure monitoring in an infant with near-complete tetra-amelia undergoing laparoscopic gastrostomy tube placement. This case suggests the potential use of such a blood pressure monitoring system for other patients with comparable deformities.

  10. [Hemodynamic adaptations in proximal cerebrovascular occlusion].

    PubMed

    De Ley, G

    1990-01-01

    In order to gain more insight into the pathophysiology of extracerebral cerebrovascular occlusion, the cerebral hemodynamic behaviour after uni- or bilateral carotid occlusion was investigated. In Wistar rats, acute occlusion of one common carotid artery leads to a moderate bilateral lowering of the resting hemispheric brain blood flow; no interhemispheric perfusion asymmetry is observed. During hypercapnia, however, a manyfold increase of the hemispheric blood flow is seen at the intact side, whereas blood flow increase at the side of the occlusion is suppressed indicating that the cerebrovascular reserve at the side of the occlusion is largely used to preserve resting hemispheric perfusion. During the days (1, 5, 15 and 30) following the occlusion, resting hemispheric blood flow is progressively restored rather rapidly (bilateral normalization on the fifth day) whereas restoration of the cerebrovascular reserve (hemispheric blood flow increase in hypercapnia) proceeds more slowly and a nearly normal hypercapnic response is reached on day thirty. Spontaneously Hypertensive Rats (SHR) show structural abnormalities of their blood vessels during the development of hypertension, leading to impaired adaptation possibilities of the cerebral vasculature after unilateral common carotid occlusion. This is indicated by the striking comparability of the compensation of hemispheric cerebral blood flow (in normo- and hypercapnia) of SH rats five days after unilateral carotid occlusion with the cerebral hemodynamic status of normotensive animals already seen 24 hours after the same occlusion. Consecutive bilateral common carotid occlusion shows that survival rate increases by increasing the interval between both occlusions. This survival relation is much more unfavorable in SH rats. The parallelism between the restoration of the measured CO2-reactivity of the blood flow in the involved hemisphere after unilateral carotid occlusion and the evolution of survival rate after

  11. Physiopathology of shock

    PubMed Central

    Bonanno, Fabrizio Giuseppe

    2011-01-01

    Shock syndromes are of three types: cardiogenic, hemorrhagic and inflammatory. Hemorrhagic shock has its initial deranged macro-hemodynamic variables in the blood volume and venous return. In cardiogenic shock there is a primary pump failure that has cardiac output/mean arterial pressure as initial deranged variables. In Inflammatory Shock it is the microcirculation that is mainly affected, while the initial deranged macrocirculation variable is the total peripheral resistance hit by systemic inflammatory response. PMID:21769210

  12. Fast Computation of Hemodynamic Sensitivity to Lumen Segmentation Uncertainty.

    PubMed

    Sankaran, Sethuraman; Grady, Leo; Taylor, Charles A

    2015-12-01

    Patient-specific blood flow modeling combining imaging data and computational fluid dynamics can aid in the assessment of coronary artery disease. Accurate coronary segmentation and realistic physiologic modeling of boundary conditions are important steps to ensure a high diagnostic performance. Segmentation of the coronary arteries can be constructed by a combination of automated algorithms with human review and editing. However, blood pressure and flow are not impacted equally by different local sections of the coronary artery tree. Focusing human review and editing towards regions that will most affect the subsequent simulations can significantly accelerate the review process. We define geometric sensitivity as the standard deviation in hemodynamics-derived metrics due to uncertainty in lumen segmentation. We develop a machine learning framework for estimating the geometric sensitivity in real time. Features used include geometric and clinical variables, and reduced-order models. We develop an anisotropic kernel regression method for assessment of lumen narrowing score, which is used as a feature in the machine learning algorithm. A multi-resolution sensitivity algorithm is introduced to hierarchically refine regions of high sensitivity so that we can quantify sensitivities to a desired spatial resolution. We show that the mean absolute error of the machine learning algorithm compared to 3D simulations is less than 0.01. We further demonstrate that sensitivity is not predicted simply by anatomic reduction but also encodes information about hemodynamics which in turn depends on downstream boundary conditions. This sensitivity approach can be extended to other systems such as cerebral flow, electro-mechanical simulations, etc.

  13. 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.

  14. Flow imaging and computing: large artery hemodynamics.

    PubMed

    Steinman, David A; Taylor, Charles A

    2005-12-01

    The objective of our session at the International Bio-Fluid Mechanics Symposium and Workshop was at the International Bio-Fluid Mechanics Symposium and Workshop to review the state-of-the-art in, and identify future directions for, imaging and computational modeling of blood flow in the large arteries and the microcirculation. Naturally, talks in other sessions of the workshop overlapped this broad topic, and so here we summarize progress within the last decade in terms of the technical development and application of flow imaging and computing, rather than the knowledge derived from specific studies. We then briefly discuss ways in these tools may be extended, and their application broadened, in the next decade. Furthermore, owing to the conceptual division between the hemodynamics of large arteries, and those within the microcirculation, we review these regimes separately: The former here by Steinman and Taylor; and the latter in a separate paper by Cristini.

  15. Hemodynamic studies of the legs under weightlessness

    NASA Technical Reports Server (NTRS)

    Thornton, W. E.; Hoffler, G. W.

    1974-01-01

    Following exposure to weightlessness, alterations in the return of blood from the legs play a crucial role in orthostatic tolerance and may be an important factor in work tolerance. To investigate some of the hemodynamic mechansism involved, an experiment was performed on the Skylab 3 and Skylab 4 missions to study arterial blood flow, venous compliance, and muscle pumping of blood. Skylab 4 results indicated that the most likely cause of increased blood flow was an increase in cardiac output secondary to increased central venous pressure caused by blood redistribution. Changes in venous compliance are thought to be primarily changes in somatic musculature which is postulated to primarily determine venous compliance of the legs. This was also thought to be demonstrated by the changes in muscle pumping. It is thought that these compliance changes, when taken with the decreased blood volume; provide a basis for the changes seen in orthostatic tolerance, work capacity and lower body negative pressure response.

  16. Hemodynamic traveling waves in human visual cortex.

    PubMed

    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.

  17. Proteasome inhibition in skeletal muscle cells unmasks metabolic derangements in type 2 diabetes.

    PubMed

    Al-Khalili, Lubna; de Castro Barbosa, Thais; Ostling, Jörgen; Massart, Julie; Cuesta, Pablo Garrido; Osler, Megan E; Katayama, Mutsumi; Nyström, Ann-Christin; Oscarsson, Jan; Zierath, Juleen R

    2014-11-01

    Two-dimensional difference gel electrophoresis (2-D DIGE)-based proteome analysis has revealed intrinsic insulin resistance in myotubes derived from type 2 diabetic patients. Using 2-D DIGE-based proteome analysis, we identified a subset of insulin-resistant proteins involved in protein turnover in skeletal muscle of type 2 diabetic patients, suggesting aberrant regulation of the protein homeostasis maintenance system underlying metabolic disease. We then validated the role of the ubiquitin-proteasome system (UPS) in myotubes to investigate whether impaired proteasome function may lead to metabolic arrest or insulin resistance. Myotubes derived from muscle biopsies obtained from people with normal glucose tolerance (NGT) or type 2 diabetes were exposed to the proteasome inhibitor bortezomib (BZ; Velcade) without or with insulin. BZ exposure increased protein carbonylation and lactate production yet impaired protein synthesis and UPS function in myotubes from type 2 diabetic patients, marking the existence of an insulin-resistant signature that was retained in cultured myotubes. In conclusion, BZ treatment further exacerbates insulin resistance and unmasks intrinsic features of metabolic disease in myotubes derived from type 2 diabetic patients. Our results highlight the existence of a confounding inherent abnormality in cellular protein dynamics in metabolic disease, which is uncovered through concurrent inhibition of the proteasome system.

  18. 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

  19. 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.

  20. Large eddy simulation of powered Fontan hemodynamics.

    PubMed

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

    2013-01-18

    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(TM)) 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.

  1. Oncogenic K-ras expression is associated with derangement of the cAMP/PKA pathway and forskolin-reversible alterations of mitochondrial dynamics and respiration.

    PubMed

    Palorini, R; De Rasmo, D; Gaviraghi, M; Sala Danna, L; Signorile, A; Cirulli, C; Chiaradonna, F; Alberghina, L; Papa, S

    2013-01-17

    The Warburg effect in cancer cells has been proposed to involve several mechanisms, including adaptation to hypoxia, oncogenes activation or loss of oncosuppressors and impaired mitochondrial function. In previous papers, it has been shown that K-ras transformed mouse cells are much more sensitive as compared with normal cells to glucose withdrawal (undergoing apoptosis) and present a high glycolytic rate and a strong reduction of mitochondrial complex I. Recent observations suggest that transformed cells have a derangement in the cyclic adenosine monophosphate/cAMP-dependent protein kinase (cAMP/PKA) pathway, which is known to regulate several mitochondrial functions. Herein, the derangement of the cAMP/PKA pathway and its impact on transformation-linked changes of mitochondrial functions is investigated. Exogenous stimulation of PKA activity, achieved by forskolin treatment, protected K-ras-transformed cells from apoptosis induced by glucose deprivation, enhanced complex I activity, intracellular adenosine triphosphate (ATP) levels, mitochondrial fusion and decreased intracellular reactive oxygen species (ROS) levels. Several of these effects were almost completely prevented by inhibiting the PKA activity. Short-time treatment with compounds favoring mitochondrial fusion strongly decreased the cellular ROS levels especially in transformed cells. These findings support the notion that glucose shortage-induced apoptosis, specific of K-ras-transformed cells, is associated to a derangement of PKA signaling that leads to mitochondrial complex I decrease, reduction of ATP formation, prevalence of mitochondrial fission over fusion, and thereby opening new approaches for development of anticancer drugs.

  2. 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.

  3. Perioperative hemodynamic instability in patients undergoing laparoscopic adrenalectomy for pheochromocytoma

    PubMed Central

    Pisarska, Magdalena; Budzyński, Andrzej

    2016-01-01

    Perioperative hemodynamic instability still remains the biggest surgical and anesthetic challenge in surgery for pheochromocytoma. The aim of this review was to discuss pre-, intra- and postoperative factors that may impact on hemodynamic condition of a patient. It describes patients’ preparation with appropriate medication, principles of surgical technique as well as risk factors for development of hemodynamic instability in postoperative period. Currently the gold standard in the treatment of pheochromocytoma is preoperative use of alpha-blockers and laparoscopic surgery. This approach allowed improving outcomes by lowering both mortality and morbidity. PMID:27867865

  4. Invasive hemodynamics of constrictive pericarditis, restrictive cardiomyopathy, and cardiac tamponade.

    PubMed

    Sorajja, Paul

    2011-05-01

    Cardiac catheterization historically has been the principal diagnostic modality for the evaluation of constrictive pericarditis, restrictive cardiomyopathy, and cardiac tamponade. In many instances, the hemodynamic consequences of these disorders can be accurately delineated with non-invasive methods. However, cardiac catheterization should be considered when there is a discrepancy between the clinical and non-invasive imaging data, and particularly may be required for the evaluation of patients with complex hemodynamic disorders. This report describes the methods and clinical utility of invasive hemodynamic catheterization for the evaluation of constriction, restriction, and cardiac tamponade.

  5. Modulation of Interleukins in Sepsis-Associated Clotting Disorders: Interplay With Hemostatic Derangement.

    PubMed

    Low, Christopher; Syed, Daneyal; Khan, Daniel; Tetik, Sermin; Walborn, Amanda; Hoppensteadt, Debra; Mosier, Michael; Fareed, Jawed

    2017-01-01

    Interleukins play a central role in the immune system and are involved in a variety of immunological, inflammatory, and infectious disease states including sepsis syndrome. Levels of interleukins may correlate with overall survival and may directly or indirectly affect some of the regulators of coagulation and fibrinolysis, thereby disrupting hemostasis and thrombosis. Our hypothesis is that in sepsis-associated coagulopathies (SACs), interleukins may be upregulated, leading to hemostatic imbalance by generating thrombogenic mediators. We profiled the levels of interleukins IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, and IL-10 in addition to d-dimer (DD) in patients with SAC and in normal donors. We observed the highest increase in interleukins IL-6 (322-fold), IL-8 (48-fold), IL-10 (72-fold), and DD (18-fold). This suggests that interleukins such as IL-6 and IL-10 have a close association with coagulopathy and fibrinolytic dysregulation in sepsis and can be considered as candidates for potential therapeutic targets in SAC.

  6. Preventive role of exercise training in autonomic, hemodynamic, and metabolic parameters in rats under high risk of metabolic syndrome development.

    PubMed

    Moraes-Silva, Ivana Cinthya; Mostarda, Cristiano; Moreira, Edson Dias; Silva, Kleiton Augusto Santos; dos Santos, Fernando; de Angelis, Kátia; Farah, Vera de Moura Azevedo; Irigoyen, Maria Claudia

    2013-03-15

    High fructose consumption contributes to metabolic syndrome incidence, whereas exercise training promotes several beneficial adaptations. In this study, we demonstrated the preventive role of exercise training in the metabolic syndrome derangements in a rat model. Wistar rats receiving fructose overload in drinking water (100 g/l) were concomitantly trained on a treadmill (FT) or kept sedentary (F) for 10 wk. Control rats treated with normal water were also submitted to exercise training (CT) or sedentarism (C). Metabolic evaluations consisted of the Lee index and glycemia and insulin tolerance test (kITT). Blood pressure (BP) was directly measured, whereas heart rate (HR) and BP variabilities were evaluated in time and frequency domains. Renal sympathetic nerve activity was also recorded. F rats presented significant alterations compared with all the other groups in insulin resistance (in mg · dl(-1) · min(-1): F: 3.4 ± 0.2; C: 4.7 ± 0.2; CT: 5.0 ± 0.5 FT: 4.6 ± 0.4), mean BP (in mmHG: F: 117 ± 2; C: 100 ± 2; CT: 98 ± 2; FT: 105 ± 2), and Lee index (in g/mm: F = 0.31 ± 0.001; C = 0.29 ± 0.001; CT = 0.27 ± 0.002; FT = 0.28 ± 0.002), confirming the metabolic syndrome diagnosis. Exercise training blunted all these derangements. Additionally, FS group presented autonomic dysfunction in relation to the others, as seen by an ≈ 50% decrease in baroreflex sensitivity and 24% in HR variability, and increases in sympathovagal balance (140%) and in renal sympathetic nerve activity (45%). These impairments were not observed in FT group, as well as in C and CT. Correlation analysis showed that both Lee index and kITT were associated with vagal impairment caused by fructose. Therefore, exercise training plays a preventive role in both autonomic and hemodynamic alterations related to the excessive fructose consumption.

  7. 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.

  8. Hemodynamic performance of the Fontan circulation compared with a normal biventricular circulation: a computational model study.

    PubMed

    Liang, Fuyou; Senzaki, Hideaki; Kurishima, Clara; Sughimoto, Koichi; Inuzuka, Ryo; Liu, Hao

    2014-10-01

    The physiological limitations of the Fontan circulation have been extensively addressed in the literature. Many studies emphasized the importance of pulmonary vascular resistance in determining cardiac output (CO) but gave little attention to other cardiovascular properties that may play considerable roles as well. The present study was aimed to systemically investigate the effects of various cardiovascular properties on clinically relevant hemodynamic variables (e.g., CO and central venous pressure). To this aim, a computational modeling method was employed. The constructed models provided a useful tool for quantifying the hemodynamic effects of any cardiovascular property of interest by varying the corresponding model parameters in model-based simulations. Herein, the Fontan circulation was studied compared with a normal biventricular circulation so as to highlight the unique characteristics of the Fontan circulation. Based on a series of numerical experiments, it was found that 1) pulmonary vascular resistance, ventricular diastolic function, and systemic vascular compliance play a major role, while heart rate, ventricular contractility, and systemic vascular resistance play a secondary role in the regulation of CO in the Fontan circulation; 2) CO is nonlinearly related to any single cardiovascular property, with their relationship being simultaneously influenced by other cardiovascular properties; and 3) the stability of central venous pressure is significantly reduced in the Fontan circulation. The findings suggest that the hemodynamic performance of the Fontan circulation is codetermined by various cardiovascular properties and hence a full understanding of patient-specific cardiovascular conditions is necessary to optimize the treatment of Fontan patients.

  9. [Hemodynamic bases for the automated quantification of the degree of obstruction in the peripheral arteries of diabetic patients].

    PubMed

    Vega Gómez, M E; Ley Pozo, J; Aldama Figueroa, A; Fernández Montequín, J I; Montalvo Diago, J; Fernández Boloña, A; Gutiérrez Jiménez, O

    1992-01-01

    In order to improve in the early diagnosis of an arterial occlusion, we proposed the bases of an automatized system that allows to recognize the hemodynamic features of diabetic patients in different stadiums of their disease. Fifty-four patients with type-II diabetes were studied. We recorded the arterial flow curves in the bilateral femoral, popliteal, pedia and tibial-posterior arteries from all of our patients. In the distal arteries from patients with hemodynamics disturbances, we found normal values of the variants measured: maximal systolic speed flow (Max A), maximal diastolic speed flow (Max D), Peurcelot's resistance (RP), pulsatility index (PI) and spectral band (SB).

  10. [Hemodynamic bases for the automatized quantification of the degree of obstruction in peripheral arteries in diabetic patients].

    PubMed

    Vega Gómez, M E; Ley Pozo, J; Aldama Figueroa, A; Fernández Montequín, J I; Montalvo Diago, J; Fernández Boloña, A; Gutiérrez Jiménez, O

    1993-01-01

    In order to improve the early diagnosis of arterial occlusions, we tried to establish the basis of an automatized system that allowed the study of the hemodynamic features of diabetic patients in the different stadii of their disease. Fifty-four patients with Diabetes Mellitus Type II were included in the study. In all of them, arterial flow curves were carried out at different levels: femoral, popliteal, pedia and tibial posterior arteries of both lower limbs. In the distal arteries of patients with hemodynamic injury, normal values of Maximal Systolic Velocity (Max A), Maximal Diastolic Velocity (Max D), Peurcelot's resistance (PR), pulsatility index (PI) and spectral band (SB), were found.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. The effect of trabeculectomy on ocular hemodynamics.

    PubMed Central

    Cantor, L B

    2001-01-01

    PURPOSE: To evaluate the effects of chronic reduction of intraocular pressure (IOP) on ocular hemodynamics. METHODS: Multisite, prospective evaluation of patients requiring trabeculectomy for treatment of glaucoma. Patients were recruited from the glaucoma service of 2 university hospitals. Patients were evaluated prior to surgery and at 3, 6, and 12 months after trabeculectomy. Color Doppler imaging was used to measure blood flow in the ophthalmic artery, central retinal artery, and short posterior ciliary arteries. Heidelberg retinal flowmetry was used to evaluate perfusion in the peripapillary and optic disc capillary beds. IOP was measured at baseline and at each study visit. RESULTS: There were highly significant reductions in IOP from presurgical baseline measures. At 3 months, mean IOP reduction was 17.1 mm Hg (62.3%; P < .001). At the 6- and 12-month evaluations, the mean IOP reductions were 15.7 mm Hg (57.3%) and 15.5 mm Hg (56.5%), respectively, P < .001. Despite the significant reduction in IOP, there were no significant differences in any ocular blood flow parameters before and after trabeculectomy. CONCLUSIONS: The findings of this study suggest that chronic reduction of IOP does not alter ocular blood flow and that IOP may be an independent risk factor for progression of glaucoma. These findings also suggest that the eye has the ability to autoregulate to chronically increased IOP over time and that additional studies evaluating the long-term effects of IOP changes are needed to further define this relationship. PMID:11797313

  17. Hemodynamic effects of red blood cell aggregation.

    PubMed

    Baskurt, Oguz K; Meiselman, Herbert J

    2007-01-01

    The influence of red blood cell (RBC) aggregation on blood flow in vivo has been under debate since early 1900's, yet a full understanding has still has not been reached. Enhanced RBC aggregation is well known to increase blood viscosity measured in rotational viscometers. However, it has been demonstrated that RBC aggregation may decrease flow resistance in cylindrical tubes, due to the formation of a cell-poor zone near the tube wall which results from the enhanced central accumulation of RBC. There is also extensive discussion regarding the effects of RBC aggregation on in vivo blood flow resistance. Several groups have reported increased microcirculatory flow resistance with enhanced RBC aggregation in experiments that utilized intravital microscopy. Alternatively, whole organ studies revealed that flow resistance may be significantly decreased if RBC aggregation is enhanced. Recently, new techniques have been developed to achieve well-controlled, graded alterations in RBC aggregation without influencing suspending phase properties. Studies using this technique revealed that the effects of RBC aggregation are determined by the degree of aggregation changes, and that this relationship can be explained by different hemodynamic mechanisms.

  18. In vivo measurement of hemodynamic information in stenosed rat blood vessels using X-ray PIV

    PubMed Central

    Park, Hanwook; Park, Jun Hong; Lee, Sang Joon

    2016-01-01

    Measurements of the hemodynamic information of blood flows, especially wall shear stress (WSS), in animal models with circulatory vascular diseases (CVDs) are important to understand the pathological mechanism of CVDs. In this study, X-ray particle image velocimetry (PIV) with high spatial resolution was applied to obtain velocity field information in stenosed blood vessels with high WSS. 3D clips fabricated with a 3D printer were applied to the abdominal aorta of a rat cadaver to induce artificial stenosis in the real blood vessel of an animal model. The velocity and WSS information of blood flows in the stenosed vessel were obtained and compared at various stenosis severities. In vivo measurement was also conducted by fastening a stenotic clip on a live rat model through surgical intervention to reduce the flow rate to match the limited temporal resolution of the present X-ray PIV system. Further improvement of the temporal resolution of the system might be able to provide in vivo measurements of hemodynamic information from animal disease models under physiological conditions. The present results would be helpful for understanding the relation between hemodynamic characteristics and the pathological mechanism in animal CVD models. PMID:27892505

  19. Hemodynamics on abrupt stoppage of centrifugal pumps during left ventricular assist.

    PubMed

    Kono, S; Nishimura, K; Nishina, T; Akamatsu, T; Komeda, M

    2000-01-01

    A magnetically suspended centrifugal pump (MSCP), developed for long-term ventricular assist, is reliable and durable because it has no shaft or seal. However, with nonvalve pumps such as a MSCP, regurgitation occurs when they accidentally stop without cannula clamping. We investigated the hemodynamics during temporary stoppage of a MSCP being used as a left ventricular assist system (LVAS), comparing two inflow cannulation sites. In four sheep (weight, 35-45 kg), microspheres were injected into the left main coronary artery to induce heart failure. An outflow cannula was sutured onto the descending aorta, and two inflow cannulae were inserted into the left atrium and the left ventricle. The MSCP was stopped with both the left ventricular cannula and left atrial cannula clamped, and the hemodynamics and P-V loops were recorded. Each cannula was then unclamped in order, and similar parameters were recorded. LVEDP increased at unclamping of the left ventricular cannula (ULVC), and rose further at unclamping of the left atrial cannula (ULAC). Aortic pressure did not change at ULVC, but decreased at ULAC. The effective systemic flow that subtracted the regurgitant flow through the MSCP from left ventricular output was half at ULVC and almost 0 at ULAC. When stopping centrifugal pumps without circuit clamping, hemodynamic deterioration is less at ULVC than at ULAC. This finding suggests that left ventricular inflow cannulation is recommended to allow more time in emergency situations.

  20. 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

  1. In vivo measurement of hemodynamic information in stenosed rat blood vessels using X-ray PIV.

    PubMed

    Park, Hanwook; Park, Jun Hong; Lee, Sang Joon

    2016-11-28

    Measurements of the hemodynamic information of blood flows, especially wall shear stress (WSS), in animal models with circulatory vascular diseases (CVDs) are important to understand the pathological mechanism of CVDs. In this study, X-ray particle image velocimetry (PIV) with high spatial resolution was applied to obtain velocity field information in stenosed blood vessels with high WSS. 3D clips fabricated with a 3D printer were applied to the abdominal aorta of a rat cadaver to induce artificial stenosis in the real blood vessel of an animal model. The velocity and WSS information of blood flows in the stenosed vessel were obtained and compared at various stenosis severities. In vivo measurement was also conducted by fastening a stenotic clip on a live rat model through surgical intervention to reduce the flow rate to match the limited temporal resolution of the present X-ray PIV system. Further improvement of the temporal resolution of the system might be able to provide in vivo measurements of hemodynamic information from animal disease models under physiological conditions. The present results would be helpful for understanding the relation between hemodynamic characteristics and the pathological mechanism in animal CVD models.

  2. In vivo measurement of hemodynamic information in stenosed rat blood vessels using X-ray PIV

    NASA Astrophysics Data System (ADS)

    Park, Hanwook; Park, Jun Hong; Lee, Sang Joon

    2016-11-01

    Measurements of the hemodynamic information of blood flows, especially wall shear stress (WSS), in animal models with circulatory vascular diseases (CVDs) are important to understand the pathological mechanism of CVDs. In this study, X-ray particle image velocimetry (PIV) with high spatial resolution was applied to obtain velocity field information in stenosed blood vessels with high WSS. 3D clips fabricated with a 3D printer were applied to the abdominal aorta of a rat cadaver to induce artificial stenosis in the real blood vessel of an animal model. The velocity and WSS information of blood flows in the stenosed vessel were obtained and compared at various stenosis severities. In vivo measurement was also conducted by fastening a stenotic clip on a live rat model through surgical intervention to reduce the flow rate to match the limited temporal resolution of the present X-ray PIV system. Further improvement of the temporal resolution of the system might be able to provide in vivo measurements of hemodynamic information from animal disease models under physiological conditions. The present results would be helpful for understanding the relation between hemodynamic characteristics and the pathological mechanism in animal CVD models.

  3. 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.

  4. 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

  5. Does Flexible Arterial Tubing Retain More Hemodynamic Energy During Pediatric Pulsatile Extracorporeal Life Support?

    PubMed

    Wang, Shigang; Kunselman, Allen R; Ündar, Akif

    2017-01-01

    The objective of this study was to evaluate the hemodynamic performance and energy transmission of flexible arterial tubing as the arterial line in a simulated pediatric pulsatile extracorporeal life support (ECLS) system. The ECLS circuit consisted of a Medos Deltastream DP3 diagonal pump head, Medos Hilite 2400 LT oxygenator, Biomedicus arterial/venous cannula (10 Fr/14 Fr), 3 feet of polyvinyl chloride (PVC) arterial tubing or latex rubber arterial tubing, primed with lactated Ringer's solution and packed red blood cells (hematocrit 40%). Trials were conducted at flow rates of 300 to 1200 mL/min (300 mL/min increments) under nonpulsatile and pulsatile modes at 36°C using either PVC arterial tubing (PVC group) or latex rubber tubing (Latex group). Real-time pressure and flow data were recorded using a custom-based data acquisition system. Mean pressures and energy equivalent pressures (EEP) were the same under nonpulsatile mode between the two groups. Under pulsatile mode, EEPs were significantly great than mean pressure, especially in the Latex group (P < 0.05). There was no difference between the two groups with regards to pressure drops across ECLS circuit, but pulsatile flow created more pressure drops than nonpulsatile flow (P < 0.05). Surplus hemodynamic energy (SHE) levels were always higher in the Latex group than in the PVC group at all sites. Although total hemodynamic energy (THE) losses were higher under pulsatile mode compared to nonpulsatile mode, more THE was delivered to the pseudopatient, particularly in the Latex group (P < 0.05). The results showed that the flexible arterial tubing retained more hemodynamic energy passing through it under pulsatile mode while mean pressures and pressure drops across the ECLS circuit were similar between PVC and latex rubber arterial tubing. Further studies are warranted to verify our findings.

  6. Hemodynamic shear stress and the endothelium in cardiovascular pathophysiology

    PubMed Central

    Davies, Peter F

    2010-01-01

    SUMMARY Endothelium lining the cardiovascular system is highly sensitive to hemodynamic shear stresses that act at the vessel luminal surface in the direction of blood flow. Physiological variations of shear stress regulate acute changes in vascular diameter and when sustained induce slow, adaptive, structural-wall remodeling. Both processes are endothelium-dependent and are systemically and regionally compromised by hyperlipidemia, hypertension, diabetes and inflammatory disorders. Shear stress spans a range of spatiotemporal scales and contributes to regional and focal heterogeneity of endothelial gene expression, which is important in vascular pathology. Regions of flow disturbances near arterial branches, bifurcations and curvatures result in complex spatiotemporal shear stresses and their characteristics can predict atherosclerosis susceptibility. Changes in local artery geometry during atherogenesis further modify shear stress characteristics at the endothelium. Intravascular devices can also influence flow-mediated endothelial responses. Endothelial flow-induced responses include a cell-signaling repertoire, collectively known as mechanotransduction, that ranges from instantaneous ion fluxes and biochemical pathways to gene and protein expression. A spatially decentralized mechanism of endothelial mechanotransduction is dominant, in which deformation at the cell surface induced by shear stress is transmitted as cytoskeletal tension changes to sites that are mechanically coupled to the cytoskeleton. A single shear stress mechanotransducer is unlikely to exist; rather, mechanotransduction occurs at multiple subcellular locations. PMID:19029993

  7. Image based numerical simulation of hemodynamics in a intracranial aneurysm

    NASA Astrophysics Data System (ADS)

    Le, Trung; Ge, Liang; Sotiropoulos, Fotis; Kallmes, David; Cloft, Harry; Lewis, Debra; Dai, Daying; Ding, Yonghong; Kadirvel, Ramanathan

    2007-11-01

    Image-based numerical simulations of hemodynamics in a intracranial aneurysm are carried out. The numerical solver based on CURVIB (curvilinear grid/immersed boundary method) approach developed in Ge and Sotiropoulos, JCP 2007 is used to simulate the blood flow. A curvilinear grid system that gradually follows the curved geometry of artery wall and consists of approximately 5M grid nodes is constructed as the background grid system and the boundaries of the investigated artery and aneurysm are treated as immersed boundaries. The surface geometry of aneurysm wall is reconstructed from an angiography study of an aneurysm formed on the common carotid artery (CCA) of a rabbit and discretized with triangular meshes. At the inlet a physiological flow waveform is specified and direct numerical simulations are used to simulate the blood flow. Very rich vortical dynamics is observed within the aneurysm area, with a ring like vortex sheds from the proximal side of aneurysm, develops and impinge onto the distal side of the aneurysm as flow develops, and destructs into smaller vortices during later cardiac cycle. This work was supported in part by the University of Minnesota Supercomputing Institute.

  8. Systemic metabolic derangement, pulmonary effects, and insulin insufficiency following subchronic ozone exposure in rats☆,☆☆

    PubMed Central

    Miller, Desinia B.; Snow, Samantha J.; Henriquez, Andres; Schladweiler, Mette C.; Ledbetter, Allen D.; Richards, Judy E.; Andrews, Debora L.; Kodavanti, Urmila P.

    2017-01-01

    Acute ozone exposure induces a classical stress response with elevated circulating stress hormones along with changes in glucose, protein and lipid metabolism in rats, with similar alterations in ozone-exposed humans. These stress-mediated changes over time have been linked to insulin resistance. We hypothesized that acute ozone-induced stress response and metabolic impairment would persist during subchronic episodic exposure and induce peripheral insulin resistance. Male Wistar Kyoto rats were exposed to air or 0.25 ppm or 1.00 ppm ozone, 5 h/day, 3 consecutive days/week (wk) for 13 wks. Pulmonary, metabolic, insulin signaling and stress endpoints were determined immediately after 13 wk or following a 1 wk recovery period (13 wk + 1 wk recovery). We show that episodic ozone exposure is associated with persistent pulmonary injury and inflammation, fasting hyperglycemia, glucose intolerance, as well as, elevated circulating adrenaline and cholesterol when measured at 13 wk, however, these responses were largely reversible following a 1 wk recovery. Moreover, the increases noted acutely after ozone exposure in non-esterified fatty acids and branched chain amino acid levels were not apparent following a subchronic exposure. Neither peripheral or tissue specific insulin resistance nor increased hepatic gluconeogenesis were present after subchronic ozone exposure. Instead, long-term ozone exposure lowered circulating insulin and severely impaired glucose-stimulated beta-cell insulin secretion. Thus, our findings in young-adult rats provide potential insights into epidemiological studies that show a positive association between ozone exposures and type 1 diabetes. Ozone-induced beta-cell dysfunction may secondarily contribute to other tissue-specific metabolic alterations following chronic exposure due to impaired regulation of glucose, lipid, and protein metabolism. PMID:27368153

  9. Hemodynamic monitoring in the intensive care unit: a Brazilian perspective

    PubMed Central

    Dias, Fernando Suparregui; Rezende, Ederlon Alves de Carvalho; Mendes, Ciro Leite; Silva Jr., João Manoel; Sanches, Joel Lyra

    2014-01-01

    Objective In Brazil, there are no data on the preferences of intensivists regarding hemodynamic monitoring methods. The present study aimed to identify the methods used by national intensivists, the hemodynamic variables they consider important, the regional differences, the reasons for choosing a particular method, and the use of protocols and continued training. Methods National intensivists were invited to answer an electronic questionnaire during three intensive care events and later, through the Associação de Medicina Intensiva Brasileira portal, between March and October 2009. Demographic data and aspects related to the respondent preferences regarding hemodynamic monitoring were researched. Results In total, 211 professionals answered the questionnaire. Private hospitals showed higher availability of resources for hemodynamic monitoring than did public institutions. The pulmonary artery catheter was considered the most trusted by 56.9% of the respondents, followed by echocardiograms, at 22.3%. Cardiac output was considered the most important variable. Other variables also considered relevant were mixed/central venous oxygen saturation, pulmonary artery occlusion pressure, and right ventricular end-diastolic volume. Echocardiography was the most used method (64.5%), followed by pulmonary artery catheter (49.3%). Only half of respondents used treatment protocols, and 25% worked in continuing education programs in hemodynamic monitoring. Conclusion Hemodynamic monitoring has a greater availability in intensive care units of private institutions in Brazil. Echocardiography was the most used monitoring method, but the pulmonary artery catheter remains the most reliable. The implementation of treatment protocols and continuing education programs in hemodynamic monitoring in Brazil is still insufficient. PMID:25607264

  10. Acute hemodynamic effects of right ventricular pacing site and pacing mode in patients with congestive heart failure secondary to either ischemic or idiopathic dilated cardiomyopathy.

    PubMed

    Gold, M R; Brockman, R; Peters, R W; Olsovsky, M R; Shorofsky, S R

    2000-05-01

    The hemodynamic effects of pacing in patients with congestive heart failure (CHF) remain controversial. Early studies reported that pacing from the right ventricular (RV) apex improved acute hemodynamic parameters in patients with left ventricular systolic dysfunction, but these findings were not confirmed in subsequent controlled studies. More recently, it has been proposed that pacing from the RV side of the ventricular septum improves hemodynamic function compared with intrinsic conduction or apical pacing. Either dual-chamber or ventricular pacing have been evaluated, again with inconsistent findings. To assess the effects of pacing site and mode on acute hemodynamic function, we evaluated 21 subjects with CHF and intrinsic conduction disease. Hemodynamics were compared in AAI, VVI, and DDD modes with pacing from the RV apex or high septum. The pacing rate was constant in each patient and the order of testing was randomized. In the absence of ventricular pacing (AAI mode), the mean systemic arterial pressure was 85 +/- 11 mm Hg, the right atrial pressure was 11 +/- 4 mm Hg, the pulmonary capillary wedge pressure was 18 +/- 8 mm Hg and the cardiac index was 2.4 +/- 0.7 L/min/m(2). Compared with AAI pacing, there were no improvements in any hemodynamic parameter with DDD pacing from either RV site. Hemodynamic function worsened with VVI pacing from both RV sites. Subgroup analyses of patients with dilated cardiomyopathy, with prolonged PR interval, or with significant mitral regurgitation also failed to demonstrate an improvement with pacing. We conclude that pacing mode but not RV pacing site affects acute hemodynamic function. Pacing in the DDD mode prevents the deleterious effects of VVI pacing in this patient population.

  11. 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

  12. 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

  13. Creatinine clearance as a substitute for the glomerular filtration rate in the assessment of glomerular hemodynamics.

    PubMed

    Okada, N; Imanishi, M; Yoshioka, K; Konishi, Y; Okumura, M; Tanaka, S; Fujii, S

    1999-11-01

    A method for the clinical assessment of glomerular hemodynamics has been published previously. We here examined whether, when using this method, renal creatinine clearance (Ccr) can be substituted for the glomerular filtration rate (GFR). The study subjects comprised 57 inpatients from Osaka City General Hospital: 30 with type 2 diabetes mellitus and 27 with chronic glomerulonephritis. During the 2-wk study, patients received a high-salt diet for 1 wk and a low-salt diet for 1 wk. Urinary sodium excretion and systemic blood pressure were measured daily. The renal plasma flow, Ccr, and plasma total protein concentration were also evaluated simultaneously on the last day of the high-salt diet. The GFR was also calculated from the fractional renal accumulation of 99mTc-diethylenetriaminepentaacetic acid (DTPA). Glomerular hemodynamics, represented by the glomerular capillary hydraulic pressure and the resistance of afferent and efferent arterioles, were calculated using the renal clearance, the plasma total protein concentration, and the pressure-natriuresis relationship. Values for renal hemodynamics with the Ccr-derived GFR were compared with those from the 99mTc-DTPA-derived GFR. Ccr values of 53 to 169 ml/min correlated with the 99mTc-DTPA-derived clearance of 39 to 179 ml/min (n=57, r=.71, p<.001). Values for the glomerular pressure and the resistances of afferent and efferent arterioles calculated using the Ccr-derived GFR correlated significantly with those calculated using the 99mTc-DTPA-derived GFR (r=.99, p<.001 and r=.99, p<.001, respectively). These results indicate that the Ccr is an accurate representation of the GFR for use in glomerular hemodynamic analysis of the pressure-natriuresis relationship.

  14. 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

  15. 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.

  16. [The radionuclide assessment of the central hemodynamic indices in patients with urolithiasis, arterial hypertension and varicocele].

    PubMed

    Darenkov, A F; Vladimirova, N N; Derevianko, I I; Darenkov, S P; Evdokimov, V V; Borisik, V I

    1991-01-01

    Basic parameters of central and intracardiac hemodynamics were studied in 49 urological patients 24 of which with urolithiasis entered group I, 13 with hypertension-group II and 12 with varicocele-group III. The patients' age averaged 46.4, 41.6 and 28.6 years, respectively. The data were provided by routine clinical and laboratory examinations, ECG, one-passage radionuclide cardiography with 132I-albumin using a radiocirculographer of Hungarian manufacture and radiocardioanalyzer RKAZ-01 made in this country. Neither marked ischemic disturbances of the myocardium nor valvular defects were revealed. Ambiguous group-specific shifts presented in central and intracardiac hemodynamics. Total peripheral vascular resistance exhibited a moderate increase while left ventricular circulation time grew 1.5-2-fold. The greater resistance can be attributed to activation of renin-angiotensin system in prolonged ischemia of renal parenchyma due to nephrolithiasis. Group II patients demonstrated parallel elevation of arterial pressure, peripheral resistance, left ventricular performance and output suggesting myocardial functional stress. In group III there was a rise in blood volume, left ventricular performance and output, cardiac index, stroke volume. This myocardial overloading may result from changes in intravascular volumetric relations characteristic of hypervolemia. These hemodynamic changes reflect adaptation in urological patients and should be accounted for in treatment and operative interventions.

  17. Protective Effects of Methylsulfonylmethane on Hemodynamics and Oxidative Stress in Monocrotaline-Induced Pulmonary Hypertensive Rats

    PubMed Central

    Mohammadi, Sadollah; Najafi, Moslem; Hamzeiy, Hossein; Maleki-Dizaji, Nasrin; Pezeshkian, Masoud; Sadeghi-Bazargani, Homayon; Darabi, Masoud; Mostafalou, Sara; Bohlooli, Shahab; Garjani, Alireza

    2012-01-01

    Methylsulfonylmethane (MSM) is naturally occurring organic sulfur that is known as a potent antioxidant/anti-inflammatory compound. The aim of this study was to investigate the effect of MSM on hemodynamics functions and oxidative stress in rats with monocrotaline- (MCT-) induced pulmonary arterial hypertension (PAH). Wistar rats were randomly assigned to 38-days treatment. MSM was administered to rats at 100, 200, and 400 mg/kg/day doses 10 days before a single dose of 60 mg/kg, IP, MCT. Hemodynamics of ventricles were determined by Powerlab AD instrument. Blood samples were obtained to evaluate changes in the antioxidative system including activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and the level of reduced glutathione (GSH) and malondialdehyde (MDA). Improvements in cardiopulmonary hemodynamics were observed in the MSM-treated pulmonary arterial hypertensive rats, with a significant reduction in right ventricular systolic pressure (RSVP) and an increase in the mean arterial pressure (MAP). The values of CAT, SOD, GSH-px activities, and GSH were significantly lower in MCT-induced PAH (P < 0.01), but they were recovered to control levels of MSM-treated groups. Our present results suggest that long-term administration of the MSM attenuates MCT-induced PAH in rats through modulation of oxidative stress and antioxidant defense. PMID:23118745

  18. Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise

    PubMed Central

    Henry, Brad; Zhao, Mingjun; Shang, Yu; Uhl, Timothy; Thomas, D. Travis; Xenos, Eleftherios S.; Saha, Sibu P.; Yu, Guoqiang

    2015-01-01

    Abstract. 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. PMID:26720871

  19. Restructuring of the vascular bed in response to hemodynamic disturbances in portal hypertension

    PubMed Central

    Garbuzenko, Dmitry Victorovich; Arefyev, Nikolay Olegovich; Belov, Dmitry Vladimirovich

    2016-01-01

    In recent years, defined progress has been made in understanding the mechanisms of hemodynamic disturbances occurring in liver cirrhosis, which are based on portal hypertension. In addition to pathophysiological disorders related to endothelial dysfunction, it was revealed: There is the restructuring of the vasculature, which includes vascular remodeling and angiogenesis. In spite of the fact that these changes are the compensatory-adaptive response to the deteriorating conditions of blood circulation, taken together, they contribute to the development and progression of portal hypertension causing severe complications such as bleeding from esophageal varices. Disruption of systemic and organ hemodynamics and the formation of portosystemic collaterals in portal hypertension commence with neovascularization and splanchnic vasodilation due to the hypoxia of the small intestine mucosa. In this regard, the goal of comprehensive treatment may be to influence on the chemokines, proinflammatory cytokines, and angiogenic factors (vascular endothelial growth factor, placental growth factor, platelet-derived growth factor and others) that lead to the development of these disorders. This review is to describe the mechanisms of restructuring of the vascular bed in response to hemodynamic disturbances in portal hypertension. Development of pathogenetic methods, which allow correcting portal hypertension, will improve the efficiency of conservative therapy aimed at prevention and treatment of its inherent complications. PMID:28083082

  20. 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.

  1. Dietary melatonin alters uterine artery hemodynamics in pregnant Holstein heifers.

    PubMed

    Brockus, K E; Hart, C G; Gilfeather, C L; Fleming, B O; Lemley, C O

    2016-04-01

    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 culture system. Twenty singleton pregnant Holstein heifers were supplemented with 20 mg of melatonin (n = 10) or no melatonin supplementation (control; n = 10) from days 190 to 262 of gestation. Maternal measurements were recorded on days 180 (baseline), 210, 240, and 262 of gestation. Total uterine blood flow was increased by 25% in the MEL-treated heifers compared with the CON. Concentrations of progesterone were decreased in MEL vs CON heifers. Total serum antioxidant capacity was increased by 43% in MEL-treated heifers when compared with CON. Activity of cytochrome P450 1A, 2C, and superoxide dismutase was increased in bovine endometrial epithelial cells treated with melatonin, whereas the melatonin receptor antagonist, luzindole, negated the increase in cytochrome P450 2C activity. Moreover, estradiol or progesterone treatment altered bovine uterine melatonin receptor expression, which could potentiate the melatonin-mediated responses during late gestation. The observed increase in total uterine blood flow during melatonin supplementation could be related to its antioxidant properties. Compromised pregnancies are typically accompanied by increased oxidative stress; therefore, melatonin could serve as a therapeutic supplementation strategy. This could lead to further fetal programming implications in conjunction with offspring growth and development postnatally.

  2. 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.

  3. 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.

  4. Seal properties of TachoSil: in vitro hemodynamic measurements.

    PubMed

    Berdajs, Denis; Bürki, Marco; Michelis, Alexandre; von Segesser, Ludwig K

    2010-06-01

    Fibrin glue products and collagen patches are frequently used as a sealing product, preventing surgical side bleedings. This is especially true in the field of cardiovascular surgery, where increasing numbers of patients are being operated with antiplatelet and anticoagulation therapy. The aim of this report was, in an in vitro hemodynamic setting, to examine the sealant properties of the TachoSil (Nycomed Pharma, Linz, Austria) patch. Burst pressure and normal force of 15 TachoSil sealed defects were measured. This was determined in a closed hydraulic system. Mean burst pressure load for a 5-mm defect was 69+/-11.4 mmHg; for a 7-mm defect was 63+/-16 mmHg; and, 62+/-16 mmHg for the defect with a diameter of 10 mm (P>0.05). The mean calculated normal force was as follows: 0.91+/-0.15 N for the 5 mm defect, 6.5+/-1.6 N for the 7 mm, and 8.1+/-0.75 N for the 10 mm defect. The TachoSil patch has the capability to seal small defects. However, at the larger defects the seal character was significantly reduced. These results suggest that the device may be a good alternative for hemostasis for small defects. The capacity to curtail or stop hemorrhage at the larger defects is unlikely.

  5. PUCA pump and IABP comparison: analysis of hemodynamic and energetic effects using a digital computer model of the circulation.

    PubMed

    Fresiello, Libera; Gu, Y John; Ferrari, Gianfranco; Di Molfetta, Arianna; Rakhorst, Gerhard

    2011-05-01

    The pulsatile catheter pump (PUCA pump) is a left ventricular assist device that provides additional flow to the left ventricle. It is usually run in order to ensure a counterpulsation effect, as in the case of the intra-aortic balloon pump (IABP). Because of this similarity, a comparison between the PUCA pump and the IABP was conducted from both the hemodynamic and energetic points of view. Numerical models of the two devices were created and connected to the CARDIOSIM cardiovascular simulator. The PUCA and IABP models were then verified using in vivo experimental data and literature data, respectively. Numerical experiments were conducted for different values of left ventricular end systolic elastance (Els) and systemic arterial compliance (Csa). The energetic comparison was conducted taking into account the diastolic pressure time index and the endocardial viability ratio. Hemodynamic results expressed as cardiac output (CO) and mean coronary blood flow (CBF) show that both the IABP and the PUCA pump efficacy decrease with higher values of Els and Csa. The IABP especially shows higher sensitivity to these parameters, to the extent that in some cases CO actually drops and CBF does not increase. On the other hand, for lower values of Csa, IABP performance improves so much that the PUCA pump flow needs to be increased in order to ensure a hemodynamic effect comparable to that of the IABP. Energetic results show a trend similar to the hemodynamic ones. The study will be continued by investigating other energetic variables and the autonomic response of the cardiovascular system.

  6. Influence of Distal Resistance and Proximal Stiffness on Hemodynamics and RV Afterload in Progression and Treatments of Pulmonary Hypertension: A Computational Study with Validation Using Animal Models

    PubMed Central

    Su, Zhenbi; Tan, Wei; Shandas, Robin; Hunter, Kendall S.

    2013-01-01

    We develop a simple computational model based on measurements from a hypoxic neonatal calf model of pulmonary hypertension (PH) to investigate the interplay between vascular and ventricular measures in the setting of progressive PH. Model parameters were obtained directly from in vivo and ex vivo measurements of neonatal calves. Seventeen sets of model-predicted impedance and mean pulmonary arterial pressure (mPAP) show good agreement with the animal measurements, thereby validating the model. Next, we considered a predictive model in which three parameters, PVR, elastic modulus (EM), and arterial thickness, were varied singly from one simulation to the next to study their individual roles in PH progression. Finally, we used the model to predict the individual impacts of clinical (vasodilatory) and theoretical (compliance increasing) PH treatments on improving pulmonary hemodynamics. Our model (1) displayed excellent patient-specific agreement with measured global pulmonary parameters; (2) quantified relationships between PVR and mean pressure and PVS and pulse pressure, as well as studiying the right ventricular (RV) afterload, which could be measured as a hydraulic load calculated from spectral analysis of pulmonary artery pressure and flow waves; (3) qualitatively confirmed the derangement of vascular wall shear stress in progressive PH; and (4) established that decreasing proximal vascular stiffness through a theoretical treatment of reversing proximal vascular remodeling could decrease RV afterload. PMID:24367392

  7. [Hemodynamic study of the elderly subject. Indications, risks and value].

    PubMed

    Ohayon, J; Colle, J P; Besse, P

    1985-04-30

    The authors record all the hemodynamic evaluations realised on aged population above severity years during two years (549 patients) representing ten per cent of the whole investigations in an hemodynamic department. The greater part of the indications were severe coronaritis resistant to medical treatment (54 percent) with unstable angina or steady state angina, and valvulopathy (37 percent) with prevalence of symptomatic aortic stenosis. The catheterization incidents and accidents do not appear more owing to the high risk pathology and to the taken precautions. The lethal accident frequency is three point five per thousand little above the frequency in a general catheterized population (two per thousand). Seldinger difficulties are easily got over by using axillary passage in case of need. The surgical interest is underlined by the fact that sixty six percent of the investigated patients will be operated. The hemodynamic evaluation in aged population between 70 and 80 years is realizable in good conditions with little risk increase when it's necessary.

  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. Non-invasive quantification of hemodynamics in human choriocapillaries

    NASA Astrophysics Data System (ADS)

    Yu, Huidan (Whitney); Chen, Rou; An, Senyou; McDonough, James; Gelfand, Bradley; Yao, Jun

    2016-11-01

    The development of retinal disease is inextricably linked to defects in the choroidal blood supply. However, to date a description of the hemodynamics in the human choroidal circulation is lacking. Through high resolution choroidal vascular network mapped from immunofluorescent labeling and confocal microscopy of human cadaver donor eyes. We noninvasively quantify hemodynamics including velocity, pressure, and wall-shear stress (WSS) in choriocapillaries through mesoscale modeling and GPU-accelerated fast computation. This is the first-ever map of hemodynamic parameters (WSS, pressure, and velocity) in anatomically accurate human choroidal vasculature in health and disease. The pore scale simulation results are used to evaluate porous media models with the same porosity and boundary conditions. School of Medicine, Indiana University.

  10. 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

  11. Are Hemodynamics Surrogate Endpoints in Pulmonary Arterial Hypertension?

    PubMed Central

    Ventetuolo, Corey E.; Gabler, Nicole B.; Fritz, Jason S.; Smith, K. Akaya; Palevsky, Harold I.; Klinger, James R.; Halpern, Scott D.; Kawut, Steven M.

    2014-01-01

    Background While frequently assessed in trials and clinical practice, hemodynamic response to therapy has never been validated as a surrogate endpoint for clinical events in pulmonary arterial hypertension (PAH). Methods and Results We performed a patient-level pooled analysis of four randomized placebo-controlled trials to determine if treatment-induced changes in hemodynamic values at 12 weeks accounted for the relationship between treatment assignment and the probability of early clinical events (death, lung transplantation, atrial septostomy, PAH hospitalization, withdrawal for clinical worsening, escalation in PAH therapy). We included 1119 subjects with PAH. The median (interquartile range) age was 48 (37 – 59), and 23% were men. 656 (59%) received active therapy (101 [15%] iloprost, 118 [18%] sitaxsentan, 204 [31%] sildenafil, and 233 [36%] subcutaneous treprostinil). Active treatment significantly lowered right atrial pressure (RAP), mean pulmonary artery pressure (mPAP), and pulmonary vascular resistance and increased cardiac output and index (p < 0.01 for all). Changes in hemodynamic values (except for RAP and mPAP) were significantly associated with the risk of a clinical event (p ≤ 0.01 for all). While active treatment approximately halved the odds of a clinical event compared to placebo (p < 0.001), changes in hemodynamics accounted for only 1.2 – 13.9% of the overall treatment effect. Conclusions Treatment-induced changes in hemodynamics at 12 weeks only partially explain the impact of therapy on the probability of early clinical events in PAH. These findings suggest that resting hemodynamics are not valid surrogate endpoints for short-term events in PAH clinical trials. PMID:24951771

  12. 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.

  13. The clinical and hemodynamic presentation of the shock patient.

    PubMed

    Summers, G

    1990-06-01

    It is the nurse's responsibility to assess the critically ill patient and to interpret data so that therapy can be directed to optimally treat that individual. Shock is a complex progressive syndrome that includes specific types, such as cardiogenic, septic, anaphylactic, and hypovolemic. Clinical and hemodynamic parameters provide clues to the specific type of shock and its clinical progress. The progression of the shock state must be monitored by critical care nurses who are knowledgeable of and proficient in clinical assessment skills and the acquisition and interpretation of significant hemodynamic data.

  14. 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.

  15. Comprehensive cognitive and cerebral hemodynamic evaluation after cranioplasty

    PubMed Central

    Coelho, Fernanda; Oliveira, Arthur Maynart; Paiva, Wellingson Silva; Freire, Fabio Rios; Calado, Vanessa Tome; Amorim, Robson Luis; Neville, Iuri Santana; de Andrade, Almir Ferreira; Bor-Seng-Shu, Edson; Anghinah, Renato; Teixeira, Manoel Jacobsen

    2014-01-01

    Decompressive craniectomy is an established procedure to lower intracranial pressure and can save patients’ lives. However, this procedure is associated with delayed cognitive decline and cerebral hemodynamics complications. Studies show the benefits of cranioplasty beyond cosmetic aspects, including brain protection, and functional and cerebrovascular aspects, but a detailed description of the concrete changes following this procedure are lacking. In this paper, the authors report a patient with trephine syndrome who underwent cranioplasty; comprehensive cognitive and cerebral hemodynamic evaluations were performed prior to and following the cranioplasty. The discussion was based on a critical literature review. PMID:24833902

  16. Study of severe scorpion envenoming following subcutaneous venom injection into dogs: Hemodynamic and concentration/effect analysis.

    PubMed

    Elatrous, Souheil; Ouanes-Besbes, Lamia; Ben Sik-Ali, Habiba; Hamouda, Zineb; BenAbdallah, Saoussen; Tilouche, Nejla; Jalloul, Faten; Fkih-Hassen, Mohamed; Dachraoui, Fahmi; Ouanes, Islem; Abroug, Fekri

    2015-09-15

    To evaluate the dose-effects of Androctonus australis hector (Aah) venom injected subcutaneously on hemodynamics and neurohormonal secretions, 10 anesthetized and ventilated mongrel dogs, were split in two groups (n = 5/group). Subcutaneous injection was done with either 0.2 mg/kg or 0.125 mg/kg of the purified G50 scorpion toxic fraction. Hemodynamic parameters using right heart catheter were recorded and plasma concentrations of catecholamine, troponin, and serum toxic fraction were measured sequentially from baseline to 120 min. We identified the dose of toxic fraction evoking characteristic hemodynamic perturbation of severe envenomation, the time-lapse to envenomation, and the associated plasma level. The injection of 0.125 mg/kg toxic fraction was not associated with significant variations in hemodynamic parameters, whereas the 0.2 mg/kg dose caused envenomation characterized by significant increase in plasma catecholamines, increased pulmonary artery occluded pressure, mean arterial pressure, and systemic vascular resistance (p < 0.05), in association with sustained decline in cardiac output (p < 0.001). Envenomation occurred by the 30th minute, and the corresponding concentration of toxic fraction was 1.14 ng/ml. The current experiment allowed the identification of the sub-lethal dose (0.2 mg/kg) of the toxic fraction of Aah administered by the subcutaneous route. Two parameters with potential clinical relevance were also uncovered: the time-lapse to envenomation and the corresponding concentration of toxic fraction.

  17. Less invasive methods of advanced hemodynamic monitoring: principles, devices, and their role in the perioperative hemodynamic optimization

    PubMed Central

    2013-01-01

    The monitoring of the cardiac output (CO) and other hemodynamic parameters, traditionally performed with the thermodilution method via a pulmonary artery catheter (PAC), is now increasingly done with the aid of less invasive and much easier to use devices. When used within the context of a hemodynamic optimization protocol, they can positively influence the outcome in both surgical and non-surgical patient populations. While these monitoring tools have simplified the hemodynamic calculations, they are subject to limitations and can lead to erroneous results if not used properly. In this article we will review the commercially available minimally invasive CO monitoring devices, explore their technical characteristics and describe the limitations that should be taken into consideration when clinical decisions are made. PMID:24472443

  18. Acute effect of hydralazine administration on pulmonary artery hemodynamics in dogs with chronic heartworm disease.

    PubMed

    Atkins, C E; Keene, B W; McGuirk, S M; Sato, T

    1994-02-01

    In an effort to better understand the role of vasodilators in the management of pulmonary hypertension associated with chronic heartworm disease (HWD), pulmonary hemodynamic measurements were obtained from 7 experimentally infected, anesthetized dogs before and after hydralazine administration (mean dose, 1.96 mg/kg of body weight). Five dogs were maintained on room air, while 2 were maintained on 100% oxygen during the hydralazine study. The hemodynamic effect of hydralazine in dogs with HWD was evaluated, using heart rate, cardiac index, mean pulmonary artery pressure, mean arterial pressure, total pulmonary resistance, total systemic resistance, total systemic resistance/total pulmonary resistance, left ventricular dP/dtmax, left ventricular end diastolic pressure, and left and right ventricular double products ([mean arterial pressure x heart rate] and [mean pulmonary artery pressure x heart rate], respectively). Responders were defined as those in which total pulmonary resistance decreased > or = 20% without an increase in mean pulmonary arterial pressure and in which heart rate increase was < or = 10%. Comparison was also made between maximal hemodynamic effect of hydralazine with that after 100% oxygen administration for 15 minutes to previously normoxemic dogs (n = 5). Significance was determined if P < 0.05, using the paired t-test. Hydralazine induced significant reductions in mean pulmonary and systemic arterial pressures and total pulmonary resistance, with no significant change in heart rate, cardiac index, total systemic resistance, left ventricular dP/dtmax, left ventricular end diastolic pressure, or right and left ventricular double products. Four (57%) of the 7 dogs studied were considered responders. Pretreatment cardiac index, mean pulmonary artery pressure, and total pulmonary resistance did not allow differentiation of responders from nonresponders.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. 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.

  20. [Influence of iron nanoparticles on cardiac performance and hemodynamics in rabbits after intravenous administration in acute experiment].

    PubMed

    Doroshenko, A M

    2014-01-01

    Iron nanoparticles are possessed by high potential in the creation of effective and safe antianemic drugs due to the enhanced biological activity of metal nanoparticles. As a step of intravenous dosage form development the study of short-term effects of iron nanoparticles on the cardiovascular system is important. Dose-dependent changes of systemic hemodynamics' parameters were established in acute experiment on rabbits after several intravenous injections of zero-valent iron nanoparticles solution.

  1. Effects of glucosamine-chondroitin combination on synovial fluid IL-1β, IL-6, TNF-α and PGE2 levels in internal derangements of temporomandibular joint

    PubMed Central

    Esen, Emin; Tatli, Ufuk

    2015-01-01

    Background The aim of the present study was to evaluate the effects of glucosamine-chondroitin sulphate combination on internal derangements of temporomandibular joint in clinical and biochemical manners. Material and Methods This randomized clinical study included 31 cases reporting joint tenderness, in which disc displacement was detected on MR imaging. In all patients, synovial fluid sampling was performed under local anesthesia. In the study group, the patients were prescribed a combination of 1500 mg glucosamine and 1200 mg chondroitin sulphate, while patients in the control group were only prescribed 50 mg tramadol HCl (twice daily) for pain control. After 8 weeks, synovial fluid sampling was repeated in the same manner. The levels of pain, maximum mouth opening (MMO), synovial fluid IL-1ß, IL-6, TNF-α and PGE2 measured before and after pharmacological intervention were compared. Results The reduction in pain levels was significant in both groups. There was no significant difference between two groups in terms of pain reduction. The improvement in MMO was significant in the study group but it was not in the control group. The MMO improvement was significantly higher in the study group compared to the control group. In the study group, significant decrease was observed in PGE2 level, while the decreases in IL-1β, IL-6 and TNF-α levels were not significant. In the control group, no significant decrease was observed in any of the inflammatory cytokines after 8 weeks, moreover IL-1ß and IL-6 levels were increased. Alterations of IL-1ß and IL-6 levels were significant in study group while TNF-α and PGE2 levels were not, compared to control group. Conclusions In conclusion, these results might suggest that glucosamine-chondroitin combination significantly increases the MMO and decreases the synovial fluid IL1β and IL6 levels in internal derangements of TMJ compared to tramadol. The modifications of synovial fluid TNF-α and PGE2 levels do not reach

  2. Full Mimicking of Coronary Hemodynamics for Ex-Vivo Stimulation of Human Saphenous Veins.

    PubMed

    Piola, Marco; Ruiter, Matthijs; Vismara, Riccardo; Mastrullo, Valeria; Agrifoglio, Marco; Zanobini, Marco; Pesce, Maurizio; Soncini, Monica; Fiore, Gianfranco Beniamino

    2017-04-01

    After coronary artery bypass grafting, structural modifications of the saphenous vein wall lead to lumen narrowing in response to the altered hemodynamic conditions. Here we present the design of a novel ex vivo culture system conceived for mimicking central coronary artery hemodynamics, and we report the results of biomechanical stimulation experiments using human saphenous vein samples. The novel pulsatile system used an aortic-like pressure for forcing a time-dependent coronary-like resistance to obtain the corresponding coronary-like flow rate. The obtained pulsatile pressures and flow rates (diastolic/systolic: 80/120 mmHg and 200/100 mL/min, respectively) showed a reliable mimicking of the complex coronary hemodynamic environment. Saphenous vein segments from patients undergoing coronary artery bypass grafting (n = 12) were subjected to stimulation in our bioreactor with coronary pulsatile pressure/flow patterns or with venous-like perfusion. After 7-day stimulation, SVs were fixed and stained for morphometric evaluation and immunofluorescence. Results were compared with untreated segments of the same veins. Morphometric and immunofluorescence analysis revealed that 7 days of pulsatile stimulation: (i) did not affect integrity of the vessel wall and lumen perimeter, (ii) significantly decreased both intima and media thickness, (iii) led to partial endothelial denudation, and (iv) induced apoptosis in the vessel wall. These data are consistent with the early vessel remodeling events involved in venous bypass adaptation to arterial flow/pressure patterns. The pulsatile system proved to be a suitable device to identify ex vivo mechanical cues leading to graft adaptation.

  3. Low-dose intravenous nitrite improves hemodynamics in a canine model of acute pulmonary thromboembolism.

    PubMed

    Dias-Junior, Carlos A C; Gladwin, Mark T; Tanus-Santos, Jose E

    2006-12-15

    Acute pulmonary thomboembolism (APT)-induced pulmonary hypertension can be counteracted by activating the nitric oxide (NO)-cGMP pathway. Recent studies have demonstrated that the naturally occurring anion nitrite (NO(2)(-)) is a bioactive storage reservoir for NO, and is reduced to NO under conditions of hypoxia and acidosis. We hypothesized that nitrite infused intravenously could attenuate the hemodynamic changes associated with APT. APT was induced with autologous blood clots injected into the right atrium in mongrel dogs. After APT (or saline), the dogs received an intravenous nitrite (or saline) infusion (6.75 micromol/kg over 15 min and then 0.28 micromol/kg/min) and hemodynamic evaluations were carried out for 2 h. Plasma nitrite concentrations were measured using ozone-based reductive chemiluminescence methodologies. APT decreased cardiac index (CI) and increased pulmonary vascular resistance index (PVRI); these effects were improved during infusions of sodium nitrite. Accordingly, nitrite infusion increased cardiac index by 28%, reduced the PVRI by 48%, and the systemic vascular resistance index (SVRI) by 21% in embolized dogs, suggesting a greater effect on the ischemic embolized vascular system than the systemic circulation following embolization. Interestingly, in nonembolized control dogs the same nitrite infusion decreased MAP and CI (all P<0.05). The nitrite infusion increased plasma nitrite concentrations by approximately 2 microM, and produced dose-dependent effects on PVRI, MAP, and SVRI. Remarkably, blood levels of nitrite as low as 500 nM decreased PVRI and SVRI in this model, suggesting a potential role of nitrite in physiological blood flow regulation. These results suggest that a low-dose nitrite infusion produces beneficial hemodynamic effects in a dog model of APT. These findings suggest a new therapeutic application for nitrite and support emerging evidence for a surprisingly potent and potentially physiological vasoactivity of nitrite.

  4. 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.

  5. Hemodynamic alterations in chronically conscious unrestrained diabetic rats.

    PubMed

    Carbonell, L F; Salom, M G; Garcia-Estañ, 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. 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/dtmax and dP/dtmin 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 state, possibly conditioning congestive heart failure. These alterations can be prevented by insulin treatment.

  6. Quantifying the Large-Scale Hemodynamics of Intracranial Aneurysms

    PubMed Central

    Byrne, G.; Mut, F.; Cebral, J.

    2013-01-01

    BACKGROUND AND PURPOSE Hemodynamics play an important role in the mechanisms that govern the initiation, growth, and possible rupture of intracranial aneurysms. The purpose of this study was to objectively characterize these dynamics, classify them, and connect them to aneurysm rupture. MATERIALS AND METHODS Image-based computational fluid dynamic simulations were used to re-create the hemodynamics of 210 patient-specific intracranial aneurysm geometries. The hemodynamics were then classified according to their spatial complexity and temporal stability by using quantities derived from vortex core lines and proper orthogonal decomposition. RESULTS The quantitative classification was compared with a previous qualitative classification performed by visual inspection. Receiver operating characteristic curves provided area-under-the-curve estimates for spatial complexity (0.905) and temporal stability (0.85) to show that the 2 classifications were in agreement. Statistically significant differences were observed in the quantities describing the hemodynamics of ruptured and unruptured intracranial aneurysms. Specifically, ruptured aneurysms had more complex and more unstable flow patterns than unruptured aneurysms. Spatial complexity was more strongly associated with rupture than temporal stability. CONCLUSIONS Complex-unstable blood flow dynamics characterized by longer core line length and higher entropy could induce biologic processes that predispose an aneurysm for rupture. PMID:23928142

  7. Assessment of Conjunctival Microvascular Hemodynamics in Stages of Diabetic Microvasculopathy

    PubMed Central

    Khansari, Maziyar M.; Wanek, Justin; Tan, Michael; Joslin, Charlotte E.; Kresovich, Jacob K.; Camardo, Nicole; Blair, Norman P.; Shahidi, Mahnaz

    2017-01-01

    Diabetes impairs the microcirculation and function of various vital tissues throughout the body. The conjunctival microcirculation can be non-invasively imaged and thus enables assessment of microvascular hemodynamics. In this study, alterations in conjunctival microvascular hemodynamics were quantitatively assessed at stages of increasing diabetic microvasculopathy based on diabetic retinopathy (DR). Subjects were categorized into non-diabetic control (C, N = 34), no clinically visible DR (NDR, N = 47), non-proliferative DR (NPDR, N = 45), and proliferative DR (PDR, N = 35). Conjunctival hemodynamic descriptors, namely vessel diameter (D), blood velocity (V), blood flow (Q), wall shear rate (WSR), and wall shear stress (WSS) were measured in arterioles and venules, and compared between DR and C subjects using generalized linear mixed models. In arterioles, V, WSR, and WSS were lower in NDR (P ≤ 0.01). V was lower in NDR than NPDR and PDR subjects (P ≤ 0.02). In venules, D was higher in NDR and NPDR (P ≤ 0.03), while V was lower in PDR (P = 0.04). Venular V and Q were higher in NPDR than PDR subjects (P ≤ 0.04). WSR and WSS were lower in all stages of DR (P ≤ 0.05), suggestive of the potential of WSS as a marker of diabetic microvasculopathy. Quantitative assessment of conjunctival hemodynamics can potentially be useful for evaluation of diabetic microvasculopathy. PMID:28387229

  8. Aortic hemodynamics and white matter hyperintensities in normotensive postmenopausal women.

    PubMed

    Barnes, Jill N; Harvey, Ronée E; Zuk, Samantha M; Lundt, Emily S; Lesnick, Timothy G; Gunter, Jeffrey L; Senjem, Matthew L; Shuster, Lynne T; Miller, Virginia M; Jack, Clifford R; Joyner, Michael J; Kantarci, Kejal

    2017-04-07

    Hypertension is associated with development of white matter hyperintensities (WMH) in the brain, which are risk factors for mild cognitive impairment. Hormonal shifts at menopause alter vascular function putting women at risk for both hypertension and WMH. Elevations in aortic hemodynamics precede the appearance of clinically defined hypertension but the relationship of aortic hemodynamics to development of WMH in women is not known. Therefore, this study aimed to characterize aortic hemodynamics in relationship to WMH in postmenopausal women. Aortic systolic and diastolic blood pressure (BP), aortic augmentation index (Alx) and aortic round trip travel time (Aortic T R) by tonometry were examined in 53 postmenopausal women (age 60 ± 2 years). WMH was calculated from fluid-attenuated inversion recovery MRI using a semi-automated segmentation algorithm. WMH as a fraction of total white matter volume positively associated with aortic systolic BP (regression coefficient = 0.018; p = 0.04) after adjusting for age. In addition, WMH fraction was positively associated with AIx (0.025; p = 0.04), and inversely associated with Aortic T R (-0.015; p = 0.04) after adjusting for age. Our results suggest that assessing aortic hemodynamics may identify individuals at risk for accelerated development of WMH and guide early treatment to reduce WMH burden and cognitive impairment in the future.

  9. 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...

  10. Hemodynamic Characterization of Peripheral Arterio-venous Malformations.

    PubMed

    Frey, Sabrina; Haine, A; Kammer, R; von Tengg-Kobligk, H; Obrist, D; Baumgartner, I

    2017-03-21

    Peripheral arterio-venous malformations (pAVMs) are congenital vascular anomalies that require treatment, due to their severe clinical consequences. The complexity of lesions often leads to misdiagnosis and ill-planned treatments. To improve disease management, we developed a computational model to quantify the hemodynamic effects of key angioarchitectural features of pAVMs. Hemodynamic results were used to predict the transport of contrast agent (CA), which allowed us to compare our findings to digital subtraction angiography (DSA) recordings of patients. The model is based on typical pAVM morphologies and a generic vessel network that represents realistic vascular feeding and draining components related to lesions. A lumped-parameter description of the vessel network was employed to compute blood pressure and flow rates. CA-transport was determined by coupling the model to a 1D advection-diffusion equation. Results show that the extent of hemodynamic effects of pAVMs, such as arterial steal and venous hypertension, strongly depends on the lesion type and its vascular architecture. Dimensions of shunting vessels strongly influence hemodynamic parameters. Our results underline the importance of the dynamics of CA-transport in diagnostic DSA images. In this context, we identified a set of temporal CA-transport parameters, which are indicative of the presence and specific morphology of pAVMs.

  11. Impact of Therapeutic Plasma Exchange on Hemodynamic Parameters in Medical Intensive Care Unit Patients: An Observational Study.

    PubMed

    Lahmer, Tobias; Messer, Marlena; Schnappauf, Christopher; Rasch, Sebastian; Fekecs, Lisa; Beitz, Analena; Eser, Stefan; Schmid, Roland M; Huber, Wolfgang

    2017-02-01

    Therapeutic plasma exchange (TPE) is an extracorporeal treatment with reported beneficial as well as detrimental effects on circulation. However, there is a lack of data using advanced hemodynamic monitoring during TPE. Therefore, we investigated the effects of TPE on hemodynamic parameters derived from transpulmonary thermodilution (TPTD) as well as the risk for transfusion-related acute lung injury (TRALI). We compared hemodynamic parameters obtained before and after a total of 30 sessions of TPE treatment in 10 intensive care unit patients. Among standard hemodynamic parameters, heart rate (P < 0.012) and systolic blood pressure (P < 0.008) significantly increase, whereas neither mean arterial pressure nor diastolic blood pressure was altered after TPE. The TPTD-derived cardiac function parameters, cardiac index (CI; P = 0.035), cardiac power index (CPI; P = 0.008), global ejection fraction (GEF; P = 0.002), and stroke volume index (SVI; P = 0.014), were significantly higher after TPE. Furthermore, systemic vascular index significantly increased (P < 0.042). Among the cardiac preload parameters, central venous pressure was significantly lower after TPE (P < 0.001), while the global end-diastolic volume index (GEDVI) did not change. Contractility marker dPmax did not change. Finally, TPE application did not significantly alter the pulmonary hydration and permeability parameters, extravascular lung water index (EVLWI) and pulmonary vascular permeability index. Vasopressor dose was not statistically significantly altered. Considering increases in SVI, CI, GEF, and CPI and stable values for GEDVI, EVLWI, and dPmax, our data do not give any hint for hemodynamic impairment or TRALI.

  12. Entrainment of spontaneous cerebral hemodynamic oscillations to behavioral responses.

    PubMed

    Pfurtscheller, Gert; Walther, Mario; Bauernfeind, Günther; Barry, Robert J; Witte, Herbert; Müller-Putz, Gernot R

    2014-04-30

    Entrainment in physiological systems can be manifest in cases where phase-coupling (synchronization) between slow intrinsic oscillations and periodic motor responses, or vice versa, takes place. To test whether voluntary movement has something in common with entrainment of slow hemodynamic oscillations to motor responses, we studied blood pressure (BP), heart rate beat-to-beat intervals (RRI) and prefrontal (de)oxyhemoglobin (Hb/HbO2) during 5min of rest, 10min of self-paced, voluntary movements and 10min of stimulus-paced movements at 10s intervals in 9 subjects. Subjects were divided into 2 groups according to the timing of voluntary finger movements. It appeared that these movements occurred at relatively regular intervals of approximately 10s in 5 subjects (group A); while 4 subjects showed random or very short inter-movement intervals (group B). Two remarkable results were obtained: first, the phase coupling (COH(2)) between BP and RRI showed a significant (p=0.0061) interaction between activity (rest vs. movement) and group (A vs. B), with an increased (p=0.0003) coupling in group A. Second, the COH(2) between BP and Hb oscillations showed a significant (p=0.034) interaction between activity and group, with a decreased (p=0.079) coupling in group B. These results suggest that subjects able to initiate self-paced, voluntary movements at relatively regular intervals of ∼10s show an entrainment potential between physiological oscillations and motor responses. This also provides the first evidence that not only physiological oscillations can be entrained to motor responses, but also motor responses (voluntary movements) can be entrained to slow intrinsic oscillations.

  13. Comprehensive physiological cardiovascular model enables automatic correction of hemodynamics in patients with acute life-threatening heart failure.

    PubMed

    Uemura, Kazunori; Kamiya, Atsunori; Shimizu, Shuji; Shishido, Toshiaki; Sugimachi, Masaru; Sunagawa, Kenji

    2006-01-01

    Saving life of patients with acute life-threatening heart failure is a major challenge. One has to correct several fatal hemodynamic abnormalities at the same time within a limited time frame. The formulation of such complicated treatments enables the development of a system that can be used to save automatically lives of patients with acute heart failure, an autopilot system. To accomplish this, we established a comprehensive physiological cardiovascular model, on which we based the design of the autopilot system. By translating hemodynamics into cardiovascular parameters (pumping ability, vascular resistance, blood volume), and by controlling each of these with individual drugs, we were able to correct blood pressure, cardiac output, and left atrial pressure to the target values rapidly (5.2 +/- 6.6, 6.8 +/- 4.6, and 11.7 +/- 9.8 minutes), stably, and simultaneously.

  14. Hemodynamic consequences of thoracic artificial lung attachment configuration: a computational model.

    PubMed

    Perlman, Carrie E; Mockros, Lyle F

    2007-01-01

    A thoracic artificial lung (TAL) is being developed to assist treatment of acute and chronic pulmonary dysfunction. The TAL is attached directly to the pulmonary circulation. Depending on pathophysiology, the TAL may be attached in series with the natural lungs (NLs), in parallel with the NLs, or in an intermediate, hybrid configuration. We developed a computational model to study hemodynamic consequences of TAL attachment configuration under pathologic conditions. The pulmonary and systemic circulations, heart, and TAL are modeled as interconnected compliances and conductances, some valved. Time-varying cardiac compliance drives the system and generates pressures and flow rates. The model includes blood pressure feedback from the sympathetic nervous system, renin-angiotensin system, and renal volume control mechanism. We used previously published results from porcine experiments to verify model accuracy. We modeled normal physiology and four disease states. A hybrid configuration with 100% cardiac output through the TAL and 40% through the NLs would deliver maximal blood flow, 3.6 to 4.6 l/min, to the TAL and be tolerated by the right ventricle. Additionally, the model suggests that reducing the large "minor loss" resistances at the graft anastomoses to the pulmonary artery would improve the hemodynamics of all TAL attachment configurations.

  15. 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.

  16. 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.

  17. Hemodynamic responses to Lachesis muta (South American bushmaster) snake venom in anesthetized rats.

    PubMed

    Dias, Lourdes; Rodrigues, Mariana A P; Rennó, André L; Stroka, Alessandra; Inoue, Bruna R; Panunto, Patrícia C; Melgarejo, Anibal R; Hyslop, Stephen

    2016-12-01

    In this work, we examined the hemodynamic responses to Lachesis muta (South American bushmaster) venom in anesthetized male Wistar rats. Venom (1.5 mg/kg, i.v.) caused immediate hypotension that was followed by a gradual return towards baseline over 60 min; there were no significant changes in heart rate, ECG parameters and respiratory rate. A higher dose (3 mg/kg, i.v.) caused sustained hypotension, variable bradycardia, respiratory depression and fluctuations in ECG; death occurred within 10-60 min. Venom injected intramuscularly (15 mg/kg) produced a smaller decrease in blood pressure that was more persistent than with 1.5 mg/kg (i.v.). Pre-treatment with atenolol (selective β1-adrenergic receptor antagonist) potentiated the response to venom (1.5 mg/kg, i.v.) and resulted in a hemodynamic profile similar to that seen with 3 mg/kg (i.v.). Macroscopically, systemic hemorrhage was seen only in the ileum, whereas histological analysis revealed extensive pulmonary hemorrhage; the heart, liver and kidney were generally unaffected. Intravascular pulmonary thrombosis occurred with venom given i.v. and i.m., but was less marked with the latter route. In rat isolated perfused hearts, venom caused a persistent decrease in left ventricular developed pressure but no change in heart rate, coronary flow or ECG; there was tissue necrosis and release of CK-MB that were abolished by pre-treating venom with the PLA2 inhibitor p-bromophenacyl bromide. These results show that in rats L. muta venom causes hypotension, bradycardia and respiratory depression, depending on the dose and route of administration. The hemodynamic responses apparently do not involve direct cardiotoxicity and are modulated by the adrenergic system.

  18. 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

  19. Bedside calculation of hemodynamic parameters with a hand-held programmable calculator. Part I.: Choice of hemodynamic formulas.

    PubMed

    Laurent, M

    1980-01-01

    Currently used hemodynamic and oxygen transport formulas are reviewed in order to chose the shortest form compatible with an optimal clinical accuracy. Programming of hand held calculators with these selected equations spares steps available in the program memory. (Acta anaesth. belg., 1980, 31, 45-52).

  20. Imaging brain hemodynamic changes during rat forepaw electrical stimulation using functional photoacoustic microscopy.

    PubMed

    Liao, Lun-De; Li, Meng-Lin; Lai, Hsin-Yi; Shih, Yen-Yu I; Lo, Yu-Chun; Tsang, Siny; Chao, Paul Chang-Po; Lin, Chin-Teng; Jaw, Fu-Shan; Chen, You-Yin

    2010-08-15

    The present study reported the development of a novel functional photoacoustic microscopy (fPAM) system for investigating hemodynamic changes in rat cortical vessels associated with electrical forepaw stimulation. Imaging of blood optical absorption by fPAM at multiple appropriately-selected and distinct wavelengths can be used to probe changes in total hemoglobin concentration (HbT, i.e., cerebral blood volume [CBV]) and hemoglobin oxygen saturation (SO(2)). Changes in CBV were measured by images acquired at a wavelength of 570nm (lambda(570)), an isosbestic point of the molar extinction spectra of oxy- and deoxy-hemoglobin, whereas SO(2) changes were sensed by pixel-wise normalization of images acquired at lambda(560) or lambda(600) to those at lambda(570). We demonstrated the capacity of the fPAM system to image and quantify significant contralateral changes in both SO(2) and CBV driven by electrical forepaw stimulation. The fPAM system complements existing imaging techniques, with the potential to serve as a favorable tool for explicitly studying brain hemodynamics in animal models.

  1. The total cavopulmonary connection resistance: a significant impact on single ventricle hemodynamics at rest and exercise

    PubMed Central

    Sundareswaran, Kartik S.; Pekkan, Kerem; Dasi, Lakshmi P.; Whitehead, Kevin; Sharma, Shiva; Kanter, Kirk R.; Fogel, Mark A.; Yoganathan, Ajit P.

    2008-01-01

    Little is known about the impact of the total cavopulmonary connection (TCPC) on resting and exercise hemodynamics in a single ventricle (SV) circulation. The aim of this study was to elucidate this mechanism using a lumped parameter model of the SV circulation. Pulmonary vascular resistance (1.96 ± 0.80 WU) and systemic vascular resistances (18.4 ± 7.2 WU) were obtained from catheterization data on 40 patients with a TCPC. TCPC resistances (0.39 ± 0.26 WU) were established using computational fluid dynamic simulations conducted on anatomically accurate three-dimensional models reconstructed from MRI (n = 16). These parameters were used in a lumped parameter model of the SV circulation to investigate the impact of TCPC resistance on SV hemodynamics under resting and exercise conditions. A biventricular model was used for comparison. For a biventricular circulation, the cardiac output (CO) dependence on TCPC resistance was negligible (sensitivity = −0.064 l·min−1·WU−1) but not for the SV circulation (sensitivity = −0.88 l·min−1·WU−1). The capacity to increase CO with heart rate was also severely reduced for the SV. At a simulated heart rate of 150 beats/min, the SV patient with the highest resistance (1.08 WU) had a significantly lower increase in CO (20.5%) compared with the SV patient with the lowest resistance (50%) and normal circulation (119%). This was due to the increased afterload (+35%) and decreased preload (−12%) associated with the SV circulation. In conclusion, TCPC resistance has a significant impact on resting hemodynamics and the exercise capacity of patients with a SV physiology. PMID:18931028

  2. Phenylephrine versus norepinephrine for initial hemodynamic support of patients with septic shock: a randomized, controlled trial

    PubMed Central

    Morelli, Andrea; Ertmer, Christian; Rehberg, Sebastian; Lange, Matthias; Orecchioni, Alessandra; Laderchi, Amalia; Bachetoni, Alessandra; D'Alessandro, Mariadomenica; Van Aken, Hugo; Pietropaoli, Paolo; Westphal, Martin

    2008-01-01

    Introduction Previous findings suggest that a delayed administration of phenylephrine replacing norepinephrine in septic shock patients causes a more pronounced hepatosplanchnic vasoconstriction as compared with norepinephrine. Nevertheless, a direct comparison between the two study drugs has not yet been performed. The aim of the present study was, therefore, to investigate the effects of a first-line therapy with either phenylephrine or norepinephrine on systemic and regional hemodynamics in patients with septic shock. Methods We performed a prospective, randomized, controlled trial in a multidisciplinary intensive care unit in a university hospital. We enrolled septic shock patients (n = 32) with a mean arterial pressure below 65 mmHg despite adequate volume resuscitation. Patients were randomly allocated to treatment with either norepinephrine or phenylephrine infusion (n = 16 each) titrated to achieve a mean arterial pressure between 65 and 75 mmHg. Data from right heart catheterization, a thermodye dilution catheter, gastric tonometry, acid-base homeostasis, as well as creatinine clearance and cardiac troponin were obtained at baseline and after 12 hours. Differences within and between groups were analyzed using a two-way analysis of variance for repeated measurements with group and time as factors. Time-independent variables were compared with one-way analysis of variance. Results No differences were found in any of the investigated parameters. Conclusions The present study suggests there are no differences in terms of cardiopulmonary performance, global oxygen transport, and regional hemodynamics when phenylephrine was administered instead of norepinephrine in the initial hemodynamic support of septic shock. Trial registration ClinicalTrial.gov NCT00639015 PMID:19017409

  3. Hemodynamic Effects of Noninvasive Ventilation in Patients with Venocapillary Pulmonary Hypertension.

    PubMed

    Bento, André Moreira; Cardoso, Luiz Francisco; Tarasoutchi, Flávio; Sampaio, Roney Orismar; Kajita, Luiz Junya; Lemos Neto, Pedro Alves

    2014-11-01

    Background: The hemodynamic effects of noninvasive ventilation with positive pressure in patients with pulmonary hypertension without left ventricular dysfunction are not clearly established. Objectives: Analyze the impact of increasing airway pressure with continuous positive airway pressure on hemodynamic parameters and, in particular, on cardiac output in patients with variable degrees of pulmonary hypertension. Methods: The study included 38 patients with pulmonary hypertension caused by mitral stenosis without left ventricular dysfunction or other significant valvulopathy. The hemodynamic state of these patients was analyzed in three conditions: baseline, after continuous positive pressure of 7 cmH2O and, finally, after pressure of 14 cmH2O. Results: The population was composed of predominantly young and female individuals with significant elevation in pulmonary arterial pressure (mean systolic pressure of 57 mmHg). Of all variables analyzed, only the right atrial pressure changed across the analyzed moments (from the baseline condition to the pressure of 14 cmH2O there was a change from 8 ± 4 mmHg to 11 ± 3 mmHg, respectively, p = 0.031). Even though there was no variation in mean cardiac output, increased values in pulmonary artery pressure were associated with increased cardiac output. There was no harmful effect or other clinical instability associated with use application of airway pressure. Conclusion: In patients with venocapillary pulmonary hypertension without left ventricular dysfunction, cardiac output response was directly associated with the degree of pulmonary hypertension. The application of noninvasive ventilation did not cause complications directly related to the ventilation systems.

  4. Patient-specific in vitro models for hemodynamic analysis of congenital heart disease - Additive manufacturing approach.

    PubMed

    Medero, Rafael; García-Rodríguez, Sylvana; François, Christopher J; Roldán-Alzate, Alejandro

    2017-03-21

    Non-invasive hemodynamic assessment of total cavopulmonary connection (TCPC) is challenging due to the complex anatomy. Additive manufacturing (AM) is a suitable alternative for creating patient-specific in vitro models for flow measurements using four-dimensional (4D) Flow MRI. These in vitro systems have the potential to serve as validation for computational fluid dynamics (CFD), simulating different physiological conditions. This study investigated three different AM technologies, stereolithography (SLA), selective laser sintering (SLS) and fused deposition modeling (FDM), to determine differences in hemodynamics when measuring flow using 4D Flow MRI. The models were created using patient-specific MRI data from an extracardiac TCPC. These models were connected to a perfusion pump circulating water at three different flow rates. Data was processed for visualization and quantification of velocity, flow distribution, vorticity and kinetic energy. These results were compared between each model. In addition, the flow distribution obtained in vitro was compared to in vivo. The results showed significant difference in velocities measured at the outlets of the models that required internal support material when printing. Furthermore, an ultrasound flow sensor was used to validate flow measurements at the inlets and outlets of the in vitro models. These results were highly correlated to those measured with 4D Flow MRI. This study showed that commercially available AM technologies can be used to create patient-specific vascular models for in vitro hemodynamic studies at reasonable costs. However, technologies that do not require internal supports during manufacturing allow smoother internal surfaces, which makes them better suited for flow analyses.

  5. 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.

  6. Hemodynamic Responses to Head and Neck Cooling

    NASA Technical Reports Server (NTRS)

    Ku, Yu-Tsuan E.; Carbo, Jorge E.; Montgomery, Leslie D.; Webbon, Bruce W.

    1994-01-01

    Personal thermoregulatory systems which provide head and neck cooling are used in the industrial and aerospace environments to alleviate thermal stress. However, little information is available regarding the physiologic and circulatory changes produced by routine operation of these systems. The objective of this study was to measure the scalp temperature and circulatory responses during use of one commercially available thermal control system. The Life Support Systems, Inc. Mark VII portable cooling system and a liquid cooling helmet were used in this study. Two EEG electrodes and one skin temperature transducer were placed on the anterior midline of the scalp to measure the scalp blood and temperature. Blood flow was measured using a bipolar impedance rheograph. Ten subjects, seated in an upright position at normal room temperature, were tested at high, medium, moderate, moderate-low and low coolant temperatures. Scalp blood flow was recorded continuously using a computer data acquisition system with a sampling frequency of 200 Hz. Scalp temperature and cooling helmet Inlet temperature was logged periodically during the test period. This study quantifies the effect of head cooling upon scalp temperature and blood flow. These data may also be used to select operational specifications of the head cooling system for biomedical applications such as the treatment of migraine headaches, scalp cooling during chemotherapy, and cooling of multiple sclerosis patients.

  7. Comparison of changes in hemodynamics between unilateral and bilateral lung volume reduction for pulmonary emphysema.

    PubMed

    Koizumi, K; Haraguchi, S; Akiyama, H; Hirata, T; Hirai, K; Mikami, I; Tanaka, S

    2001-10-01

    This study was aimed to compare changes in hemodynamics between unilateral (UL) or simultaneous bilateral (BL) lung volume reduction surgery (LVRS) for chronic obstructive lung disease. Sixteen patients underwent LVRS by stapler resection with neodymium: yttrium-alminum-garnet (Nd: YAG) laser ablation; five underwent BL-LVRS (four by median sternotomy and one by thoracoscopy) and 11 underwent UL-LVRS by thoracoscopy. Four patients had multiple bullae within pulmonary emphysema. At preoperation and 6, 12, 24, and 48 hours postoperatively, hemodynamics and right ventricular performance were evaluated. UL- and BL-LVRS reduced afterload of the right and left ventricle postoperatively. Although the pulmonary arterial resistance increased after surgery, the total pulmonary resistance decreased (p=0.001) in association with the reduced systemic vascular resistance (p=0.001). These reductions improved cardiopulmonary circulation, resulting in increased stroke volume and cardiac output (p=0.003). The right ventricular ejection fraction showed minimal change 48 hours postoperation. Two patients died of pneumonia caused by persistent air leakage. In conclusion, both the UL- and BL-LVRS showed similar effectiveness in terms of improvement in the systemic and cardiopulmonary circulation after LVRS, if there were no postoperative complications. We concluded that we had to reduce and repair the persistent air leakage after LVRS.

  8. Remodeling of blood vessels: responses of diameter and wall thickness to hemodynamic and metabolic stimuli.

    PubMed

    Pries, Axel R; Reglin, Bettina; Secomb, Timothy W

    2005-10-01

    Vascular functions, including tissue perfusion and peripheral resistance, reflect continuous structural adaptation (remodeling) of blood vessels in response to several stimuli. Here, a theoretical model is presented that relates the structural and functional properties of microvascular networks to the adaptive responses of individual segments to hemodynamic and metabolic stimuli. All vessels are assumed to respond, according to a common set of adaptation rules, to changes in wall shear stress, circumferential wall stress, and tissue metabolic status (indicated by partial pressure of oxygen). An increase in vessel diameter with increasing wall shear stress and an increase in wall mass with increased circumferential stress are needed to ensure stable vascular adaptation. The model allows quantitative predictions of the effects of changes in systemic hemodynamic conditions or local adaptation characteristics on vessel structure and on peripheral resistance. Predicted effects of driving pressure on the ratio of wall thickness to vessel diameter are consistent with experimental observations. In addition, peripheral resistance increases by approximately 65% for an increase in driving pressure from 50 to 150 mm Hg. Peripheral resistance is predicted to be markedly increased in response to a decrease in vascular sensitivity to wall shear stress, and to be decreased in response to increased tissue metabolic demand. This theoretical approach provides a framework for integrating available information on structural remodeling in the vascular system and predicting responses to changing conditions or altered vascular reactivity, as may occur in hypertension.

  9. The role of renal hemodynamics in the antihypertensive action of mepirodipine, a new calcium antagonist.

    PubMed

    Noda, H; Fujita, T; Ogata, E

    1992-01-01

    To evaluate the role of regional hemodynamics in the anti-hypertensive effect of mepirodipine, a new dihydropyridine-derivative calcium antagonist, we measured systemic, renal, hepatic, and forearm hemodynamics in 10 patients with essential hypertension treated with mepirodipine (15 mg/day) for 4 weeks. After the administration of mepirodipine, a significant decline in mean blood pressure (-13.8 +/- 2.3%, p less than 0.01) accompanied by a decrease in systemic vascular resistance (-21.1 +/- 2.6%, p less than 0.01) was observed. Although forearm vascular resistance did not change significantly, both renal (-19.2 +/- 6.7%, p less than 0.01) and hepatic vascular resistance (-17.6 +/- 3.8%, p less than 0.01) decreased considerably. The decrements of mean blood pressure with mepirodipine did not correlate with those of hepatic or forearm vascular resistance but correlated positively with those of renal vascular resistance (r = 0.699, p less than 0.05). Moreover, the increment of renal blood flow with mepirodipine was negatively correlated with the pretreatment level of renal blood flow (r = -0.670, p less than 0.05); renal blood flow increased to a greater extent in patients with lower pretreatment renal blood flow. These findings suggest that the oral administration of mepirodipine in patients with essential hypertension can produce selective vasodilation in the renal vasculature, which may play an important role in the relatively long-term antihypertensive effect of this drug.

  10. 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

  11. [Pulmonary hemodynamics and hemostasis in rabbits exposed to high altitude].

    PubMed

    Almerekova, A A; Tartakovskiĭ, V N; Isakova, Zh T

    1993-01-01

    Pulmonary hemodynamics, homeostasis and red blood parameters were studied in 77 rabbits in the mountains of the Tien Shan (3200 m above sea-level). Exposure of animals in alpine environment gave rise to pulmonary hypertension, polycythemia, alterations of homeostasis by the pattern of hyper- and hypocoagulation syndrome. On certain stages of adaptation products of paracoagulation were observed in blood as well as intravascular aggregation of formed elements, increased sensitivity of blood plates to platelet activation, increased fibrinolysis. Given existing hypothesis about involvement of changes in homeostasis and red blood in the pathogenesis of altitude pulmonary hypertension, the coefficients of paired linear correlation between indices of pulmonary hemodynamics and blood have been calculated. These coefficients are valid only for low values of the ratio.

  12. Clinical relevance of fetal hemodynamic monitoring: Perinatal implications.

    PubMed

    Pruetz, Jay D; Votava-Smith, Jodie; Miller, David A

    2015-08-01

    Comprehensive assessment of fetal wellbeing involves monitoring of fetal growth, placental function, central venous pressure, and cardiac function. Ultrasound evaluation of the fetus using 2D, color Doppler, and pulse-wave Doppler techniques form the foundation of antenatal diagnosis of structural anomalies, rhythm abnormalities and altered fetal circulation. Accurate and timely prenatal identification of the fetus at risk is critical for appropriate parental counseling, antenatal diagnostic testing, consideration for fetal intervention, perinatal planning, and coordination of postnatal care delivery. Fetal hemodynamic monitoring and serial assessment are vital to ensuring fetal wellbeing, particularly in the setting of complex congenital anomalies. A complete hemodynamic evaluation of the fetus gives important information on the likelihood of a smooth postnatal transition and contributes to ensuring the best possible outcome for the neonate.

  13. [The hemodynamic characterization of the diabetic patient with arterial calcifications].

    PubMed

    Vega Gómez, M E; Ley Pozo, J; Aldama Figueroa, A; Lima Santana, B; Montalvo Diago, J; Bustillo, C; Fernández Boloña, A; Gutiérrez Jiménez, O; Ramirez Muñoz, O; Martínez Hernández, R

    1993-01-01

    This study was designed to describe the presence of calcifications according to the clinical features of the diabetic patient and the hemodynamics of the calcified arteries. With this purpose, 197 lower limbs from diabetic patients (type I and II) and carbon-hydrate intolerant patients, were studied. In all of the patients, the pressure ratio leg/arm was measured. On the same way, the arterial flow velocity was recorded using the Doppler ultrasonography on the pedia and postero-tibial arteries. The arterial calcifications, evident on the radiography of the foot, were more frequent between the type I patients and the neuro-infections diabetic foot. According to the hemodynamics point of view, we found a trend of association of more pathologic arterial flow velocity curves with the presence of calcifications (specially on the intima layer). It was also remarkable that an arterial incomprensibility was always associated with arterial calcifications.

  14. Current Developments and Future Applications of Intracoronary Hemodynamics

    PubMed Central

    Coverstone, Edward; Shapiro, Robert; Singh, Jasvindar

    2015-01-01

    Intracoronary hemodynamic assessment of the physiologic significance of coronary lesions improves clinical outcomes in patients with coronary artery disease. Coronary flow velocity reserve (CFVR), fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and index of microcirculatory resistance (IMR) utilize sensor-mounted guidewires to approximate coronary flow. CFVR and FFR rely on pharmacologic administration of adenosine to achieve hyperemia and diagnose epicardial lesion severity. As an adenosine-free index, iFR utilizes a wave-free period in mid-late diastole during which resistance is constant and low to assess lesion significance. IMR combines hyperemic pressure measurements with thermodilution to quantify microvascular resistance. We review the physiology, clinical trials, and clinical applications of these invasive hemodynamic assessments. PMID:25946656

  15. 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.

  16. A numerical hemodynamic tool for predictive vascular surgery.

    PubMed

    Marchandise, Emilie; Willemet, Marie; Lacroix, Valérie

    2009-01-01

    We suggest a new approach to peripheral vascular bypass surgery planning based on solving the one-dimensional (1D) governing equations of blood flow in patient-specific models. The aim of the present paper is twofold. First, we present the coupled 1D-0D model based on a discontinuous Galerkin method in a comprehensive manner, such as it becomes accessible to a wider community than the one of mathematicians and engineers. Then we show how this model can be applied to predict hemodynamic parameters and help therefore clinicians to choose for the best surgical option bettering the hemodynamics of a bypass. After presenting some benchmark problems, we apply our model to a real-life clinical application, i.e. a femoro-popliteal bypass surgery. Our model shows good agreement with preoperative and intraoperative measurements of velocity and pressure and post-surgical reports.

  17. Combined Visualization of Vessel Deformation and Hemodynamics in Cerebral Aneurysms.

    PubMed

    Meuschke, Monique; Voss, Samuel; Beuing, Oliver; Preim, Bernhard; Lawonn, Kai

    2017-01-01

    We present the first visualization tool that combines patient-specific hemodynamics with information about the vessel wall deformation and wall thickness in cerebral aneurysms. Such aneurysms bear the risk of rupture, whereas their treatment also carries considerable risks for the patient. For the patient-specific rupture risk evaluation and treatment analysis, both morphological and hemodynamic data have to be investigated. Medical researchers emphasize the importance of analyzing correlations between wall properties such as the wall deformation and thickness, and hemodynamic attributes like the Wall Shear Stress and near-wall flow. Our method uses a linked 2.5D and 3D depiction of the aneurysm together with blood flow information that enables the simultaneous exploration of wall characteristics and hemodynamic attributes during the cardiac cycle. We thus offer medical researchers an effective visual exploration tool for aneurysm treatment risk assessment. The 2.5D view serves as an overview that comprises a projection of the vessel surface to a 2D map, providing an occlusion-free surface visualization combined with a glyph-based depiction of the local wall thickness. The 3D view represents the focus upon which the data exploration takes place. To support the time-dependent parameter exploration and expert collaboration, a camera path is calculated automatically, where the user can place landmarks for further exploration of the properties. We developed a GPU-based implementation of our visualizations with a flexible interactive data exploration mechanism. We designed our techniques in collaboration with domain experts, and provide details about the evaluation.

  18. Neural correlates of single vessel hemodynamic responses in vivo

    PubMed Central

    O'Herron, Philip; Chhatbar, Pratik Y; Levy, Manuel; Shen, Zhiming; Schramm, Adrien E; Lu, Zhongyang; Kara, Prakash

    2016-01-01

    Neural activation increases blood flow locally. This vascular signal is used by functional imaging techniques to infer the location and strength of neural activity1,2. However, the precise spatial scale over which neural and vascular signals are correlated is unknown. Furthermore, the relative role of synaptic and spiking activity in driving hemodynamic signals is controversial3-9. Prior studies recorded local field potentials (LFPs) as a measure of synaptic activity together with spiking activity and low-resolution hemodynamic imaging. Here we used two-photon microscopy to measure sensory-evoked responses of individual blood vessels (dilation, blood velocity) while imaging synaptic and spiking activity in the surrounding tissue using fluorescent glutamate and calcium sensors. In cat primary visual cortex, where neurons are clustered by their preference for stimulus orientation, we discovered new maps for excitatory synaptic activity, which were organized similar to spiking activity but were less selective for stimulus orientation and direction. We generated tuning curves for individual vessel responses for the first time and found that parenchymal vessels in cortical layer 2/3 were orientation selective. Neighboring penetrating arterioles had different orientation preferences. Pial surface arteries in cats, as well as surface arteries and penetrating arterioles in rat visual cortex (where orientation maps do not exist10), responded to visual stimuli but had no orientation selectivity. We integrated synaptic or spiking responses around individual parenchymal vessels in cats and established that the vascular and neural responses had the same orientation preference. However, synaptic and spiking responses were more selective than vascular responses—vessels frequently responded robustly to stimuli that evoked little to no neural activity in the surrounding tissue. Thus, local neural and hemodynamic signals were partly decoupled. Together, these results indicate that

  19. 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.

  20. [Hemodynamic analysis of a centrifugal blood pump].

    PubMed

    Wang, Yang; Yang, Ming; Xu, Zihao; Zhuang, Xiaoqi; Li, Qilei; Xu, Liang

    2015-01-01

    This paper built the mathematical model of a centrifugal blood pump, which was designed by ourselves, combined it with that of the human cardiovascular system and simulated the coupling system using Matlab. Then we set up the experiment platform, linked the blood pump to mock human cardiovascular system in case of three-stage heart failure, and measured aortic pressure and flow under different speed. The comparison between experiment results and simulation results not only indicates the coupling model is correct and the blood pump works well, but also shows that with the increase of blood pump speed, the pulsation of aortic pressure and flow will be reduced, this situation will affect the structure and function of blood vessels.

  1. 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

  2. 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.

  3. Left Ventricular Mass: Correlation with Fatness, Hemodynamics and Renal Morphology

    PubMed Central

    Wykrętowicz, Mariusz; Katulska, Katarzyna; Milewska, Agata; Krauze, Tomasz

    2014-01-01

    Summary Background Left ventricular mass (LVM) is correlated with body composition and central hemodynamics as well as kidney function. Recently, fat-free mass has been considered to be more strongly correlated with LVM in comparison to other descriptors of fatness. We therefore address the question of whether comprehensive descriptors of fatness, central hemodynamics and renal characteristics demonstrate the association with left ventricular mass in healthy non-obese population. Material/Methods 119 healthy non-obese subjects (53 females, 66 males, mean age 50 yrs) were evaluated. Central hemodynamics was measured by Pulse Wave Analysis, left ventricular mass was assessed by echocardiography, fatness was evaluated by anthropometry, bioimpedance, and ultrasound. Results Left ventricular mass index (LVMI) correlated to the same extent with central and peripheral blood pressure but not with descriptors of wave reflection. Fat-free mass as well as intraabdominal fat correlated to a similar extent with LVMI. Kidney morphological characteristics indexed to body surface area were associated inversely and independently with LVMI. Conclusions Comprehensive assessment of fatness reinforced the concept that intraabdominal fat compartment is strongly correlated with left ventricular mass. Descriptors of wave reflection are not associated with left ventricular mass. The interrelationsh between kidney morphology and LVMI indicates that such associations may be a biologically plausible phenomenon. PMID:25436020

  4. [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.

  5. 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.

  6. Particle Image Velocimetry studies of bicuspid aortic valve hemodynamics

    NASA Astrophysics Data System (ADS)

    Saikrishnan, Neelakantan; Yap, Choon-Hwai; Yoganathan, Ajit P.

    2010-11-01

    Bicuspid aortic valves (BAVs) are a congenital anomaly of the aortic valve with two fused leaflets, affecting about 1-2% of the population. BAV patients have much higher incidence of valve calcification & aortic dilatation, which may be related to altered mechanical forces from BAV hemodynamics. This study aims to characterize BAV hemodynamics using Particle Image Velocimetry(PIV). BAV models are constructed from normal explanted porcine aortic valves by suturing two leaflets together. The valves are mounted in an acrylic chamber with two sinuses & tested in a pulsatile flow loop at physiological conditions. 2D PIV is performed to obtain flow fields in three planes downstream of the valve. The stenosed BAV causes an eccentric jet, resulting in a very strong vortex in the normal sinus. The bicuspid sinus vortex appears much weaker, but more unstable. Unsteady oscillatory shear stresses are also observed, which have been associated with adverse biological response; characterization of the hemodynamics of BAVs will provide the first step to understanding these processes better. Results from multiple BAV models of varying levels of stenosis will be presented & higher stenosis corresponded to stronger jets & increased aortic wall shear stresses.

  7. 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.

  8. Influence of Parent Artery Segmentation and Boundary Conditions on Hemodynamic Characteristics of Intracranial Aneurysms

    PubMed Central

    Hua, Yufeng; Oh, Je Hoon

    2015-01-01

    Purpose The purpose of this study is to explore the influence of segmentation of the upstream and downstream parent artery and hemodynamic boundary conditions (BCs) on the evaluated hemodynamic factors for the computational fluid dynamics (CFD) analysis of intracranial aneurysms. Materials and Methods Three dimensional patient-specific aneurysm models were analyzed by applying various combinations of inlet and outlet BCs. Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases. Results Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs. When the inlet length was relatively short, different inlet BCs showed different hemodynamic factors and the calculated hemodynamic factors were also dependent on the inlet length. However, when the inlet length (L) was long enough (L>20D, where D is the diameter of inlet section), the hemodynamic factors became similar regardless of the inlet BCs and lengths. The error due to different inlet BCs was negligible. The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length. Conclusion Simulated hemodynamic factors are highly sensitive to inlet BCs and upstream parent artery segmentation. The results of this work can provide an insight into how to build models and to apply BCs for more accurate estimation of hemodynamic factors from CFD simulations of intracranial aneurysms. PMID:26256976

  9. Catheter-Directed Therapy in Acute Pulmonary Embolism with Right Ventricular Dysfunction: A Promising Modality to Provide Early Hemodynamic Recovery

    PubMed Central

    Dilektasli, Asli Gorek; Cetinoglu, Ezgi Demirdogen; Acet, Nilufer Aylin; Erdogan, Cuneyt; Ursavas, Ahmet; Ozkaya, Guven; Coskun, Funda; Karadag, Mehmet; Ege, Ercument

    2016-01-01

    Background Catheter-directed therapy (CDT) for pulmonary embolism (PE) is considered as an alternative to systemic thrombolysis (ST) in patients with hemodynamically unstable acute PE who are considered at high bleeding risk for ST. We aimed to evaluate the efficacy and safety of CDT in the management of acute PE with right ventricular dysfunction (RVD). The primary outcomes were mortality, clinical success, and complications. Secondary outcomes were change in hemodynamic parameters in the first 24 hours following the procedure. Material/Methods Medical records of consecutive patients diagnosed as having acute massive or submassive PE with accompanying RVD treated by immediate CDT at our institution from January 2007 to January 2014 were reviewed. Patient characteristics, mortality, achievement of clinical success, and minor and major bleeding complications were analyzed in the overall study group, as well as massive vs. submassive PE subgroups. Change in hemodynamic parameters in the second, eighth, and 24th hours after the CDT procedure were also analyzed. Results The study included 15 consecutive patients (M/F=10/5) with a mean age of 54.2±16.6 years who underwent immediate CDT. Nine of the patients had submassive PE, and 6 had massive PE. In-hospital mortality rate was 13.3% (95% CI, 0.04–0.38). One major, but not life-threatening, bleeding episode was evident in the whole group. Hemodynamic parameters were stabilized and clinical success was achieved in 14/15 (93.3%; 95% CI, 70.2–98.8) of the patients in the first 24 hours. Notably, the hemodynamic recovery was significantly evident in the first 8 hours after the procedure. Conclusions CDT is a promising treatment option for patients with acute PE with RVD with no fatal bleeding complication. In experienced centers, CDT should be considered as a first-line treatment for patients with acute PE and RVD and contraindications for ST, with the advantage of providing early hemodynamic recovery. PMID:27081754

  10. Quantitative mapping of hemodynamics in the lung, brain, and dorsal window chamber-grown tumors using a novel, automated algorithm

    PubMed Central

    Fontanella, Andrew N.; Schroeder, Thies; Hochman, Daryl W.; Chen, Raymond E.; Hanna, Gabi; Haglund, Michael M.; Secomb, Timothy W.; Palmer, Gregory M.; Dewhirst, Mark W.

    2013-01-01

    Hemodynamic properties of vascular beds are of great interest in a variety of clinical and laboratory settings. However, there presently exists no automated, accurate, technically simple method for generating blood velocity maps of complex microvessel networks. Here we present a novel algorithm that addresses this problem by applying pixel-by-pixel cross-correlation to video data. Temporal signals at every spatial coordinate are compared with signals at neighboring points, generating a series of correlation maps from which speed and direction are calculated. User assisted definition of vessel geometries is not required, and sequential data are analyzed automatically, without user bias. Velocity measurements are validated against the dual-slit method and against capillary flow with known velocities. The algorithm is tested in three different biological models. Along with simultaneously acquired hemoglobin saturation and vascular geometry information, the hemodynamic maps presented here demonstrate an accurate, quantitative method of analyzing dynamic vascular systems. PMID:23781901

  11. The Impact of Hemodialysis and Arteriovenous Access Flow on Extracranial Hemodynamic Changes in End-Stage Renal Disease Patients

    PubMed Central

    2016-01-01

    In this study, we characterized cerebral blood flow changes by assessment of blood flow parameters in neck arteries using carotid duplex ultrasonography and predictive factors for these hemodynamic changes. Hemodynamic variables were measured before and during hemodialysis in 81 patients with an arteriovenous access in their arm. Hemodialysis produced significant lowering in peak systolic velocity and flow volume of neck arteries and calculated total cerebral blood flow (1,221.9 ± 344.9 [before hemodialysis] vs. 1,085.8 ± 319.2 [during hemodialysis], P < 0.001). Effects were greater in vessels on the same side as the arteriovenous access and these changes were influenced by arteriovenous access flow during hemodialysis, both in the CCA (r = -0.277, P = 0.015) and the VA (r = -0.239, P = 0.034). The change of total cerebral blood flow during hemodialysis was independently related with age, presence of diabetes, and systemic blood pressure. PMID:27478334

  12. Near-infrared measurements of hemodynamic and oxygenation changes on the frontal cortex during breath holding, hyperventilation, and natural sleep

    NASA Astrophysics Data System (ADS)

    Noponen, Tommi E.; Kotilahti, Kalle; Toppila, Jussi; Nissila, Ilkka T.; Salmi, Tapani; Kajava, Timo T.; Katila, Toivo E.

    2003-07-01

    We have developed a frequency-domain near-infrared device suitable for physiological studies in human. In this work, a four-channel configuration of the instrument is applied to monitor hemodynamic and oxygenation changes in the frontal cortex of volunteers during different ventilation tasks. We use four different source-receiver separations (2, 3, 4, and 5 cm) and three wavelengths (760, 808, and 830 nm) to test the sensitivity of these parameters to cardiovascular and metabolic changes. Low-frequency oscillations (~ 0.02 Hz) and variations in heart rate during different ventilation tasks are investigated as well. We also study physiological changes during natural sleep using the frequency-domain instrument simultaneously with a polysomnography system containing a pulse oximeter. Our results indicate that hemodynamic and oxygenation changes in the frontal cortex during natural sleep can be detected using near-infrared measurements.

  13. Decomposition of Near-Infrared Spectroscopy Signals Using Oblique Subspace Projections: Applications in Brain Hemodynamic Monitoring.

    PubMed

    Caicedo, Alexander; Varon, Carolina; Hunyadi, Borbala; Papademetriou, Maria; Tachtsidis, Ilias; Van Huffel, Sabine

    2016-01-01

    Clinical data is comprised by a large number of synchronously collected biomedical signals that are measured at different locations. Deciphering the interrelationships of these signals can yield important information about their dependence providing some useful clinical diagnostic data. For instance, by computing the coupling between Near-Infrared Spectroscopy signals (NIRS) and systemic variables the status of the hemodynamic regulation mechanisms can be assessed. In this paper we introduce an algorithm for the decomposition of NIRS signals into additive components. The algorithm, SIgnal DEcomposition base on Obliques Subspace Projections (SIDE-ObSP), assumes that the measured NIRS signal is a linear combination of the systemic measurements, following the linear regression model y = Ax + ϵ. SIDE-ObSP decomposes the output such that, each component in the decomposition represents the sole linear influence of one corresponding regressor variable. This decomposition scheme aims at providing a better understanding of the relation between NIRS and systemic variables, and to provide a framework for the clinical interpretation of regression algorithms, thereby, facilitating their introduction into clinical practice. SIDE-ObSP combines oblique subspace projections (ObSP) with the structure of a mean average system in order to define adequate signal subspaces. To guarantee smoothness in the estimated regression parameters, as observed in normal physiological processes, we impose a Tikhonov regularization using a matrix differential operator. We evaluate the performance of SIDE-ObSP by using a synthetic dataset, and present two case studies in the field of cerebral hemodynamics monitoring using NIRS. In addition, we compare the performance of this method with other system identification techniques. In the first case study data from 20 neonates during the first 3 days of life was used, here SIDE-ObSP decoupled the influence of changes in arterial oxygen saturation from the

  14. Decomposition of Near-Infrared Spectroscopy Signals Using Oblique Subspace Projections: Applications in Brain Hemodynamic Monitoring

    PubMed Central

    Caicedo, Alexander; Varon, Carolina; Hunyadi, Borbala; Papademetriou, Maria; Tachtsidis, Ilias; Van Huffel, Sabine

    2016-01-01

    Clinical data is comprised by a large number of synchronously collected biomedical signals that are measured at different locations. Deciphering the interrelationships of these signals can yield important information about their dependence providing some useful clinical diagnostic data. For instance, by computing the coupling between Near-Infrared Spectroscopy signals (NIRS) and systemic variables the status of the hemodynamic regulation mechanisms can be assessed. In this paper we introduce an algorithm for the decomposition of NIRS signals into additive components. The algorithm, SIgnal DEcomposition base on Obliques Subspace Projections (SIDE-ObSP), assumes that the measured NIRS signal is a linear combination of the systemic measurements, following the linear regression model y = Ax + ϵ. SIDE-ObSP decomposes the output such that, each component in the decomposition represents the sole linear influence of one corresponding regressor variable. This decomposition scheme aims at providing a better understanding of the relation between NIRS and systemic variables, and to provide a framework for the clinical interpretation of regression algorithms, thereby, facilitating their introduction into clinical practice. SIDE-ObSP combines oblique subspace projections (ObSP) with the structure of a mean average system in order to define adequate signal subspaces. To guarantee smoothness in the estimated regression parameters, as observed in normal physiological processes, we impose a Tikhonov regularization using a matrix differential operator. We evaluate the performance of SIDE-ObSP by using a synthetic dataset, and present two case studies in the field of cerebral hemodynamics monitoring using NIRS. In addition, we compare the performance of this method with other system identification techniques. In the first case study data from 20 neonates during the first 3 days of life was used, here SIDE-ObSP decoupled the influence of changes in arterial oxygen saturation from the

  15. Impact of the postpump resistance on pressure-flow waveform and hemodynamic energy level in a neonatal pulsatile centrifugal pump.

    PubMed

    Wang, Shigang; Haines, Nikkole; Richardson, J Scott; Dasse, Kurt A; Undar, Akif

    2009-01-01

    This study tested the impact of different postpump resistances on pulsatile pressure-flow waveforms and hemodynamic energy output in a mock extracorporeal system. The circuit was primed with a 40% glycerin-water mixture, and a PediVAS centrifugal pump was used. The pre- and postpump pressures and flow rates were monitored via a data acquisition system. The postpump resistance was adjusted using a Hoffman clamp at the outlet of the pump. Five different postpump resistances and rotational speeds were tested with nonpulsatile (NP: 5000 RPM) and pulsatile (P: 4000 RPM) modes. No backflow was found when using pulsatile flow. With isoresistance, increased arterial resistances decreased pump flow rates (NP: from 1,912 ml/min to 373 ml/min; P: from 1,485 ml/min to 288 ml/min), increased postpump pressures (NP: from 333 mm Hg to 402 mm Hg; P: from 223 mm Hg to 274 mm Hg), and increased hemodynamic energy output with pulsatile mode. Pump flow rate correlated linearly with rotational speed (RPMs) of the pump, whereas postpump pressures and hemodynamic energy outputs showed curvilinear relationships with RPMs. The maximal pump flow rate also increased from 618 ml/min to 4,293 ml/min with pulsatile mode and from 581 ml/min to 5,665 ml/min with nonpulsatile mode. Results showed that higher postpump resistance reduced the pump flow range, and increased postpump pressure and surplus hemodynamic energy output with pulsatile mode. Higher rotational speeds also generated higher pump flow rates, postpump pressures, and increased pulsatility.

  16. Neonatal aortic arch hemodynamics and perfusion during cardiopulmonary bypass.

    PubMed

    Pekkan, Kerem; Dur, Onur; Sundareswaran, Kartik; Kanter, Kirk; Fogel, Mark; Yoganathan, Ajit; Undar, Akif

    2008-12-01

    The objective of this study is to quantify the detailed three-dimensional (3D) pulsatile hemodynamics, mechanical loading, and perfusion characteristics of a patient-specific neonatal aortic arch during cardiopulmonary bypass (CPB). The 3D cardiac magnetic resonance imaging (MRI) reconstruction of a pediatric patient with a normal aortic arch is modified based on clinical literature to represent the neonatal morphology and flow conditions. The anatomical dimensions are verified from several literature sources. The CPB is created virtually in the computer by clamping the ascending aorta and inserting the computer-aided design model of the 10 Fr tapered generic cannula. Pulsatile (130 bpm) 3D blood flow velocities and pressures are computed using the commercial computational fluid dynamics (CFD) software. Second order accurate CFD settings are validated against particle image velocimetry experiments in an earlier study with a complex cardiovascular unsteady benchmark. CFD results in this manuscript are further compared with the in vivo physiological CPB pressure waveforms and demonstrated excellent agreement. Cannula inlet flow waveforms are measured from in vivo PC-MRI and 3 kg piglet neonatal animal model physiological experiments, distributed equally between the head-neck vessels and the descending aorta. Neonatal 3D aortic hemodynamics is also compared with that of the pediatric and fetal aortic stages. Detailed 3D flow fields, blood damage, wall shear stress (WSS), pressure drop, perfusion, and hemodynamic parameters describing the pulsatile energetics are calculated for both the physiological neonatal aorta and for the CPB aorta assembly. The primary flow structure is the high-speed canulla jet flow (approximately 3.0 m/s at peak flow), which eventually stagnates at the anterior aortic arch wall and low velocity flow in the cross-clamp pouch. These structures contributed to the reduced flow pulsatility (85%), increased WSS (50%), power loss (28%), and blood

  17. [Analysis of hemodynamics in late ontogenesis in subjects with different regimes of motor activity].

    PubMed

    Bykov, A T; Miakotnykh, V V; Khodasevich, L S; Zaĭtsev, I A

    2011-01-01

    Th present study was designed to examine 409 practically healthy men at the age of 50 to 79 years differing in terms of daily locomotor activities. They were divided into 4 groups each comprising subjects whose age differed within 10 years. Group 1 included former high-class athletes continuing physical exercises. Group 2 consisted of former high-class athletes practicing sedentary lifestyle. Group 3 contained subjects regularly doing health-improving physical exercises and group 4 those who had never been engaged in sports activities. The main parameters measured in all the subjects included the heart rate, arterial pressure, stroke volume, pulse pressure, minute blood volume, cardiac index, total peripheral vascular resistance, and mean dynamic arterial pressure. It was shown that both the routine regime of motor activity and its history in the preceding period have significant influence on hemodynamic characteristics in late ontogenesis. The high level of routine motor activity in the former high-class athletes enabled them to maintain for a long time good functional state of the cadiovascular system compared with the former athletes practicing sedentary lifestyle and the subjects who had never been engaged in sports activities. The former athletes practicing sedentary lifestyle developed the hypokinetic type of hemodynamics by the age of 60-69 years.

  18. Time-Frequency Characterization of Cerebral Hemodynamics of Migraine Sufferers as Assessed by NIRS Signals

    NASA Astrophysics Data System (ADS)

    Molinari, Filippo; Rosati, Samanta; Liboni, William; Negri, Emanuela; Mana, Ornella; Allais, Gianni; Benedetto, Chiara

    2010-12-01

    Near-infrared spectroscopy (NIRS) is a noninvasive system for the real-time monitoring of the concentration of oxygenated ([InlineEquation not available: see fulltext.]) and reduced (HHb) hemoglobin in the brain cortex. [InlineEquation not available: see fulltext.] and HHb concentrations vary in response to cerebral autoregulation. Sixty-eight women (14 migraineurs without aura, 49 migraineurs with aura, and 5 controls) performed breath-holding and hyperventilation during NIRS recordings. Signals were processed using the Choi-Williams time-frequency transform in order to measure the power variation of the very-low frequencies (VLF: 20-40 mHz) and of the low frequencies (LF: 40-140 mHz). Results showed that migraineurs without aura present different LF and VLF power levels than controls and migraineurs with aura. The accurate power measurement of the time-frequency analysis allowed for the discrimination of the subjects' hemodynamic patterns. The time-frequency analysis of NIRS signals can be used in clinical practice to assess cerebral hemodynamics.

  19. The hemodynamic effects of methylene blue when administered at the onset of cardiopulmonary bypass.

    PubMed

    Maslow, Andrew D; Stearns, Gary; Butala, Parag; Batula, Parag; Schwartz, Carl S; Gough, Jeffrey; Singh, Arun K

    2006-07-01

    Hypotension occurs during cardiopulmonary bypass (CPB), in part because of induction of the inflammatory response, for which nitric oxide and guanylate cyclase play a central role. In this study we examined the hemodynamic effects of methylene blue (MB), an inhibitor of guanylate cyclase, administered during cardiopulmonary bypass (CPB) to patients taking angiotensin-converting enzyme inhibitors. Thirty patients undergoing cardiac surgery were randomized to receive either MB (3 mg/kg) or saline (S) after institution of CPB and cardioplegic arrest. CPB was managed similarly for all study patients. Hemodynamic data were assessed before, during, and after CPB. The use of vasopressors was recorded. All study patients experienced a similar reduction in mean arterial blood pressure (MAP) and systemic vascular resistance (SVR) with the onset of CPB and cardioplegic arrest. MB increased MAP and SVR and this effect lasted for 40 minutes. The saline group demonstrated a persistently reduced MAP and SVR throughout CPB. The saline group received phenylephrine more frequently during CPB, and more norepinephrine after CPB to maintain a desirable MAP. The MB group recorded significantly lower serum lactate levels despite equal or greater MAP and SVR. In conclusion, administration of MB after institution of CPB for patients taking angiotensin-converting enzyme inhibitors increased MAP and SVR and reduced the need for vasopressors. Furthermore, serum lactate levels were lower in MB patients, suggesting more favorable tissue perfusion.

  20. Label-Free Determination of Hemodynamic Parameters in the Microcirculaton with Third Harmonic Generation Microscopy

    PubMed Central

    Dietzel, Steffen; Pircher, Joachim; Nekolla, A. Katharina; Gull, Mazhar; Brändli, André W.; Pohl, Ulrich; Rehberg, Markus

    2014-01-01

    Determination of blood flow velocity and related hemodynamic parameters is an important aspect of physiological studies which in many settings requires fluorescent labeling. Here we show that Third Harmonic Generation (THG) microscopy is a suitable tool for label-free intravital investigations of the microcirculation in widely-used physiological model systems. THG microscopy is a non-fluorescent multi-photon scanning technique combining the advantages of label-free imaging with restriction of signal generation to a focal spot. Blood flow was visualized and its velocity was measured in adult mouse cremaster muscle vessels, non-invasively in mouse ear vessels and in Xenopus tadpoles. In arterioles, THG line scanning allowed determination of the flow pulse velocity curve and hence the heart rate. By relocating the scan line we obtained velocity profiles through vessel diameters, allowing shear rate calculations. The cell free layer containing the glycocalyx was also visualized. Comparison of the current microscopic resolution with theoretical, diffraction limited resolution let us conclude that an about sixty-fold THG signal intensity increase may be possible with future improved optics, optimized for 1200–1300 nm excitation. THG microscopy is compatible with simultaneous two-photon excited fluorescence detection. It thus also provides the opportunity to determine important hemodynamic parameters in parallel to common fluorescent observations without additional label. PMID:24933027

  1. Transcranial imaging of functional cerebral hemodynamic changes in single blood vessels using in vivo photoacoustic microscopy

    PubMed Central

    Liao, Lun-De; Lin, Chin-Teng; Shih, Yen-Yu I; Duong, Timothy Q; Lai, Hsin-Yi; Wang, Po-Hsun; Wu, Robby; Tsang, Siny; Chang, Jyh-Yeong; Li, Meng-Lin; Chen, You-Yin

    2012-01-01

    Optical imaging of changes in total hemoglobin concentration (HbT), cerebral blood volume (CBV), and hemoglobin oxygen saturation (SO2) provides a means to investigate brain hemodynamic regulation. However, high-resolution transcranial imaging remains challenging. In this study, we applied a novel functional photoacoustic microscopy technique to probe the responses of single cortical vessels to left forepaw electrical stimulation in mice with intact skulls. Functional changes in HbT, CBV, and SO2 in the superior sagittal sinus and different-sized arterioles from the anterior cerebral artery system were bilaterally imaged with unambiguous 36 × 65-μm2 spatial resolution. In addition, an early decrease of SO2 in single blood vessels during activation (i.e., ‘the initial dip') was observed. Our results indicate that the initial dip occurred specifically in small arterioles of activated regions but not in large veins. This technique complements other existing imaging approaches for the investigation of the hemodynamic responses in single cerebral blood vessels. PMID:22472612

  2. Effect of inhibition of converting enzyme on renal hemodynamics and sodium management in polycystic kidney disease.

    PubMed

    Torres, V E; Wilson, D M; Burnett, J C; Johnson, C M; Offord, K P

    1991-10-01

    We compared the tubular transport of sodium and the erythrocyte sodium-lithium countertransport activity in hypertensive patients with autosomal dominant polycystic kidney disease (ADPKD) and in normotensive control subjects. In addition, we assessed the effects of inhibition of converting enzyme on renal hemodynamics and sodium excretion in hypertensive patients with ADPKD to provide information on mechanisms responsible for the increased renal vascular resistance and filtration fraction and the adjustment of the pressure-natriuresis relationship during saline expansion, observed in patients with ADPKD, hypertension, and preserved renal function. In comparison with normotensive control subjects, the hypertensive patients with ADPKD had lower renal plasma flows, higher renal vascular resistances and filtration fractions, and similar proximal and distal fractional reabsorptions of sodium. The administration of enalapril resulted in significant increases in the renal plasma flow and significant reductions in mean arterial pressure, renal vascular resistance, and filtration fraction, but the glomerular filtration rate remained unchanged. Despite the significant reduction in mean arterial pressure during inhibition of converting enzyme, the distal fractional reabsorption of sodium decreased while the total fractional excretion of sodium remained unchanged or increased slightly. No significant differences were detected between the normotensive control subjects and the hypertensive patients with ADPKD in erythrocyte sodium-lithium countertransport activity, plasma renin activity, plasma aldosterone concentration, or atrial natriuretic factor. These results suggest that the renal renin-angiotensin system plays a central role in the alterations in renal hemodynamics and sodium management associated with the development of hypertension in ADPKD.

  3. In-vitro study of the hemodynamics of intracraneal saccular aneurysms

    NASA Astrophysics Data System (ADS)

    Cantón, G.; Varga, C. M.; Lasheras, J. C.; Levy, D. I.

    2001-11-01

    The study of the hemodynamic forces which cause the formation, growth and eventual rupture of aneurysms in the intracranial arteries is of great importance, since cerebral aneurysms are the most common cause of intracranial hemorrhage in adult population. The hemodynamic forces that are believed to contribute to the degeneration of the internal elastic membrane of the arteries are shear stresses, and pressure. The goal of this study is to investigate, through in-vitro models, the effects of blood pressure, cardiac rate, and geometry of the arterial bifurcati on on the distribution of pressure and shear stresses on the walls of saccular aneurysms. A range of arterial geometries is studied while simulating both the pulsatility of the flow and the compliance of the arterial wall. A Particle Image Velocimetry (PIV) system based on a double Nd:Yag pulse laser was used to measure the three dimensional velocity field inside the aneurysm and in the arterial bifurcation. The resulting distribution of pressure and shear stresses are analyzed in the context of the various three-dimensional vortical structures forming in these flows. Furthermore, the effect of placing stents of varying stiffness and porosity on the shear stresses along the aneurysm wall are also investigated.

  4. Endotoxin-induced hemodynamic changes in dogs: role of thromboxane and prostaglandin I2.

    PubMed

    Bottoms, G D; Johnson, M A; Roesel, O F

    1983-08-01

    Plasma concentrations of thromboxane and prostaglandin I2 (PGI2) before and after IV injection of endotoxin and resulting hemodynamic changes were evaluated. Effects of flunixin meglumine on plasma concentrations of these prostaglandins and the related hemodynamic changes were also determined. Shock was induced in 2 groups of anesthetized dogs. Four dogs were given endotoxin only and 4 dogs were given endotoxin and then were treated with flunixin meglumine. Arterial blood pressure (BP), cardiac output (CO), and heart rate were measured, and blood samples were collected at postendotoxin hours (PEH) 0, 0.1, 0.25, 0.5, 1, 2, 3, and 4. Plasma thromboxane and PGI2 concentrations were increased in canine endotoxic shock. Thromboxane concentration was highest early in shock, and appeared to be associated with an initial decrease in BP and CO. The increased concentration of PGI2 was associated with systemic hypotension at PEH 1 to 2. Treatment of dogs with flunixin meglumine at PEH 0.07 prevented further increase of thromboxane and blocked the release of PGI2, resulting in an increased CO, BP, and tissue aerobic metabolism.

  5. A Wearable Patch to Enable Long-Term Monitoring of Environmental, Activity and Hemodynamics Variables

    PubMed Central

    Etemadi, Mozziyar; Inan, Omer T.; Heller, J. Alex; Hersek, Sinan; Klein, Liviu; Roy, Shuvo

    2015-01-01

    We present a low power multi-modal patch designed for measuring activity, altitude (based on high-resolution barometric pressure), a single-lead electrocardiogram, and a tri-axial seismocardiogram (SCG). Enabled by a novel embedded systems design methodology, this patch offers a powerful means of monitoring the physiology for both patients with chronic cardiovascular diseases, and the general population interested in personal health and fitness measures. Specifically, to the best of our knowledge, this patch represents the first demonstration of combined activity, environmental context, and hemodynamics monitoring, all on the same hardware, capable of operating for longer than 48 hours at a time with continuous recording. The three-channels of SCG and one-lead ECG are all sampled at 500 Hz with high signal-to-noise ratio, the pressure sensor is sampled at 10 Hz, and all signals are stored to a microSD card with an average current consumption of less than 2 mA from a 3.7 V coin cell (LIR2450) battery. In addition to electronic characterization, proof-of-concept exercise recovery studies were performed with this patch, suggesting the ability to discriminate between hemodynamic and electrophysiology response to light, moderate, and heavy exercise. PMID:25974943

  6. A Wearable Patch to Enable Long-Term Monitoring of Environmental, Activity and Hemodynamics Variables.

    PubMed

    Etemadi, Mozziyar; Inan, Omer T; Heller, J Alex; Hersek, Sinan; Klein, Liviu; Roy, Shuvo

    2016-04-01

    We present a low power multi-modal patch designed for measuring activity, altitude (based on high-resolution barometric pressure), a single-lead electrocardiogram, and a tri-axial seismocardiogram (SCG). Enabled by a novel embedded systems design methodology, this patch offers a powerful means of monitoring the physiology for both patients with chronic cardiovascular diseases, and the general population interested in personal health and fitness measures. Specifically, to the best of our knowledge, this patch represents the first demonstration of combined activity, environmental context, and hemodynamics monitoring, all on the same hardware, capable of operating for longer than 48 hours at a time with continuous recording. The three-channels of SCG and one-lead ECG are all sampled at 500 Hz with high signal-to-noise ratio, the pressure sensor is sampled at 10 Hz, and all signals are stored to a microSD card with an average current consumption of less than 2 mA from a 3.7 V coin cell (LIR2450) battery. In addition to electronic characterization, proof-of-concept exercise recovery studies were performed with this patch, suggesting the ability to discriminate between hemodynamic and electrophysiology response to light, moderate, and heavy exercise.

  7. The effect of low-dose oxytocin infusion on cerebral hemodynamics in pregnant women.

    PubMed

    van Veen, Teelkien R; Belfort, Michael A; Zeeman, Gerda G

    2011-08-01

    We investigated the cerebrovascular effects of continuous infusion of low-dose oxytocin in normal pregnant women undergoing induction of labor. In our prospective observational study, middle cerebral artery velocity was measured with transcranial Doppler ultrasound in 25 healthy, normotensive, nonsmoking patients undergoing induction of labor. No vasoactive drugs were used before or during the study period. Measurements were made at baseline and 15, 30, 60, and 120 minutes after oxytocin initiation. Mean arterial pressure, cerebral perfusion pressure, resistance index, resistance area product, and cerebral flow index at different times were calculated and compared using one-way analysis of variance (ANOVA) for repeated measures or Friedman repeated-measures ANOVA as appropriate, with P<0.05 regarded as significant. No significant systemic or cerebrovascular changes were noted after oxytocin initiation, and there was no correlation between the dosage administered and any hemodynamic parameter. Induction-dose oxytocin does not significantly affect selected cerebral hemodynamic parameters in the first 2 hours after initiation.

  8. Predisposition to essential hypertension and renal hemodynamics in recent-onset insulin-dependent diabetic patients.

    PubMed

    Hannedouche, T P; Marques, L P; Guicheney, P; Lacour, B; Boitard, C; Grünfeld, J P

    1992-10-01

    The offspring of essential hypertensive parents have been found to exhibit abnormalities in renal hemodynamics and sodium handling before the eventual occurrence of hypertension. The reported abnormalities represent a wide spectrum of changes including increased GFR, normal or decreased RPF, slight increase in blood pressure (although within the normal range), and an exaggerated natriuresis response to a sodium load. The heterogeneity of these abnormalities may reflect the specific conditions of the studies, the lability of the changes, or different subgroups of subjects with genetic predisposition to essential hypertension. Several lines of evidence have suggested a relationship between hypertension and the development of diabetic nephropathy in insulin-dependent diabetics. This laboratory has found that recent-onset insulin-dependent diabetics can exhibit renal hemodynamics abnormalities very early in the course of diabetes according to a positive or negative family history of essential hypertension. These changes include increased GFR and mean arterial pressure, but no differences in renal sodium and lithium handling in diabetics with a genetic predisposition to essential hypertension. In addition, diabetics with a positive family history of essential hypertension exhibited a more-marked vasodilative response to an acute interruption of the renin-angiotensin system, further suggesting inadequate angiotensin modulation of renal vascular tone. The significance of these abnormalities in relation to the development of diabetic nephropathy requires further investigation.

  9. Effects of carotid hypotension on aortic hemodynamics in the unanesthetized dog.

    PubMed

    Cox, R H; Fronek, A; Peterson, L H

    1975-11-01

    The effects of occlusion of the brachiocephalic artery on aortic hemodynamics were assessed in 12 chronically instrumented dogs in the unanesthetized state. Continuous measurements of ascending aorta pressure and flow were made. In the steady state following occlusion, heart rate increased by 36% and mean arterial pressure by 45%, while cardiac output was unchanged from preocclusion levels. Hydraulic power delivery to the systemic circulation by the left ventricle was increased during occlusion, while the fraction of total power associated with pulsations decreased. Values of peripheral resistance and ascending aorta input impedance were both increased during occlusion. Graded occlusions of the brachiocephalic artery produced graded, monotonic increases in the entire aortic impedance spectrum between 2 and 20 Hz with more sensitive responses occurring with the smaller, submaximal responses. Considered with results of previous studies, these results suggest that activation of smooth muscle in large conduit arteries is also associated with the pressor response which accompanies carotid hypotension and that such activation has a hemodynamically significant effect.

  10. EVALUATION AND TREATMENT OF A PATIENT DIAGNOSED WITH ADHESIVE CAPSULITIS CLASSIFIED AS A DERANGEMENT USING THE MCKENZIE METHOD: A CASE REPORT

    PubMed Central

    Swanson, Brian T.

    2016-01-01

    ABSTRACT Background/Purpose The McKenzie Method of mechanical diagnosis and therapy (MDT) is supported in the literature as a valid and reliable approach to the management of spine injuries. It can also be applied to the peripheral joints, but has not been explored through research to the same extent. This method sub-classifies an injury based on tissue response to mechanical loading and repeated motion testing, with directional preferences identified in the exam used to guide treatment. The purpose of this case report is to demonstrate the assessment, intervention, and clinical outcomes of a subject classified as having a shoulder derangement syndrome using MDT methodology. Case Description The subject was a 52-year-old female with a four-week history of insidious onset left shoulder pain, referred to physical therapy with a medical diagnosis of adhesive capsulitis. She presented with pain (4-7/10 on the visual analog scale [VAS]) and decreased shoulder range of motion that limited her activities of daily living and work capabilities (Upper Extremity Functional Index (UEFI) score: 55/80). Active and passive ranges of motion (A/PROM) were limited in all planes. Repeated motion testing was performed, with an immediate reduction in pain and increased shoulder motion in all planes following repeated shoulder extension. As a result, her MDT classification was determined to be derangement syndrome. Treatment involved specific exercises, primarily repeated motions, identified as symptom alleviating during the evaluation process. Outcomes The subject demonstrated significant improvements in the UEFI (66/80), VAS (0-2/10), and ROM within six visits over eight weeks. At the conclusion of treatment, A/PROM was observed to be equal to the R shoulder without pain. Discussion This subject demonstrated improved symptoms and functional abilities following evaluation and treatment using MDT methodology. While a cause-effect relationship cannot be determined with a single case, MDT

  11. Hemodynamic and electrophysiological spontaneous low-frequency oscillations in the cortex: directional influences revealed by Granger causality.

    PubMed

    Huang, Liangming; Liu, Yadong; Li, Ming; Hu, Dewen

    2014-01-15

    We used a combined electrophysiological/hemodynamic system to examine low-frequency oscillations (LFOs) in spontaneous neuronal activities (spike trains and local field potentials) and hemodynamic signals (cerebral blood flow) recorded from the anesthetized rat somatosensory and visual cortices. The laser Doppler flowmetry (LDF) probe was tilted slightly to approach the area in which a microelectrode array (MEA) was implanted for simultaneous recordings. Spike trains (STs) were converted into continuous-time rate functions (CRFs) using the ST instantaneous firing rates. LFOs were detected for all three of the components using the multi-taper method (MTM). The frequencies of these LFOs ranged from 0.052 to 0.167 Hz (mean±SD, 0.10±0.026 Hz) for cerebral blood flow (CBF), from 0.027 to 0.26 Hz (mean±SD, 0.12±0.041 Hz) for the CRFs of the STs and from 0.04 to 0.19 Hz (mean±SD, 0.11±0.035 Hz) for local field potentials (LFPs). We evaluated the Granger causal relationships of spontaneous LFOs among CBF, LFPs and CRFs using Granger causality (GC) analysis. Significant Granger causal relationships were observed from LFPs to CBF, from STs to CBF and from LFPs to STs at approximately 0.1 Hz. The present results indicate that spontaneous LFOs exist not only in hemodynamic components but also in neuronal activities of the rat cortex. To the best of our knowledge, the present study is the first to identify Granger causal influences among CBF, LFPs and STs and show that spontaneous LFOs carry important Granger causal influences from neural activities to hemodynamic signals.

  12. A comparative study of esmolol and dexmedetomidine on hemodynamic responses to carbon dioxide pneumoperitoneum during laparoscopic surgery

    PubMed Central

    Bhattacharjee, Dhurjoti Prosad; Saha, Sauvik; Paul, Sanjib; Roychowdhary, Shibsankar; Mondal, Shirsendu; Paul, Suhrita

    2016-01-01

    Background: Carbon dioxide pneumoperitoneum for laparoscopic surgery increases arterial pressures, heart rate (HR), and systemic vascular resistance. In this randomized, single-blind, placebo-controlled clinical study, we investigated and compared the efficacy of esmolol and dexmedetomidine to provide perioperative hemodynamic stability in patients undergoing laparoscopic cholecystectomy. Methods: Sixty patients, of either sex undergoing elective laparoscopic cholecystectomy, were randomly allocated into three groups containing twenty patients each. Group E received bolus dose of 500 μg/kg intravenous (IV) esmolol before pneumoperitoneum followed by an infusion of 100 μg/kg/min. Group D received bolus dose of 1 μg/kg IV dexmedetomidine before pneumoperitoneum followed by infusion of 0.2 μg/kg/h. Group S (control) received saline 0.9%. Results: Mean arterial pressure and HR in Group E and D were significantly less throughout the period of pneumoperitoneum in comparison to Group S. IV nitroglycerine was required in 45% (9 out of 20) patients in Group S to control intraoperative hypertension, and it was clinically significant in comparison to Group E and D. Conclusion: Both esmolol and dexmedetomidine attenuate the adverse hemodynamic response to pneumoperitoneum and provide hemodynamic stability during laparoscopic surgery. PMID:27746555

  13. Is skeletal muscle luxury perfusion the main hemodynamic effect of high-dose insulin in cardiac surgery?

    PubMed

    Lindholm, L; Nilsson, B; Kirnö, K; Sellgren, J; Nilsson, F; Jeppsson, A

    2000-08-01

    Insulin, in combination with glucose and potassium (GIK), can be used in heart surgery to improve hemodynamic performance. This study evaluates the role of skeletal muscle vasodilation in hemodynamic effects of high-dose GIK therapy early after coronary surgery. Thirty-three male patients undergoing coronary artery bypass grafting were included in a prospective, randomized and controlled study. Eleven patients received infusions of mixed amino acids (11.4 g) and insulin solution (225 IU insulin, glucose with the glucose clamp technique, and potassium), 11 patients received infusions of mixed amino acids (11.4 g) and 11 patients served as control subjects. During combined insulin and amino acid infusion, cardiac output increased by 13+/-3% (+0.6+/-0.2 L x min(-1)) and systemic vascular resistance decreased by 24+/-3% (-320+/-46 dyn x s x cm(-5)). The changes differed from those in the control group (CO: -0.2+/-0.1 L x min(-1), p < 0.05; SVR: +136+/-42 dyn x s x cm(-5), p < 0.05). Changes in skeletal muscle perfusion and leg vascular resistance did not differ significantly among the groups. At most, changes in leg blood flow could explain 40% of the changes in cardiac output. Skeletal muscle luxury perfusion is not the main hemodynamic effect of high-dose insulin in the early postoperative period after coronary surgery.

  14. Differences in the Pulsatile Component of the Skin Hemodynamic Response to Verbal Fluency Tasks in the Forehead and the Fingertip

    PubMed Central

    Takahashi, Toshimitsu; Takikawa, Yoriko; Kawagoe, Reiko

    2016-01-01

    Several studies have claimed that hemodynamic signals measured by near-infrared spectroscopy (NIRS) on the forehead exhibit different patterns during a verbal fluency task (VFT) in various psychiatric disorders, whereas many studies have noted that NIRS signals can reflect task-related changes in skin blood flow. If such a task-related skin hemodynamic response is also observed in the fingertip, a simpler biomarker may be developed. Furthermore, determining the difference in the response pattern may provide physiological insights into the condition. We found that the magnitude of the pulsatile component in skin hemodynamic signals increased on the forehead (p < 0.001 for N = 50, p = 0.073 for N = 8) but decreased on the fingertip (p < 0.001, N = 8) during the VFT, whereas the rate in both areas increased (p < 0.02, N = 8). We also did not find a repetition effect in both the rate and the magnitude on the fingertip, whereas the effect was present in the magnitude (p < 0.02, N = 8) but not in the rate on the forehead. These results suggest that the skin vasomotor system in the forehead could have a different vessel mechanism to psychological tasks compared to the fingertip. PMID:26905432

  15. Effects of positive intrathoracic pressure on pulmonary and systemic hemodynamics.

    PubMed

    Tyberg, J V; Grant, D A; Kingma, I; Moore, T D; Sun, Y; Smith, E R; Belenkie, I

    2000-02-01

    The Frank-Starling Law accounts for many changes in cardiac performance previously attributed to changes in contractility in that changes in contractility might have been incorrectly inferred from changing ventricular function curves (i.e. systolic performance plotted against filling pressure) if diastolic compliance also changed. To apply the Frank-Starling Law in the presence of changing diastolic compliance, it is necessary to measure end-diastolic volume directly or to calculate end-diastolic transmural pressure, which requires that pericardial pressure be known. Under most normal circumstances, increased intrathoracic pressure (and other interventions, such as vasodilators or lower-body negative pressure, that decrease central blood volume) decreases the transmural end-diastolic pressures of both ventricles, their end-diastolic volumes and stroke work. However, when ventricular interaction is significant, the effects of these interventions might be quite different; this may be important in patients with heart-failure. Although these interventions decrease RV transmural pressure, they may increase LV transmural pressure, end-diastolic volume, and thus stroke work by the Frank-Starling mechanism.

  16. 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.

  17. Neural and Hemodynamic Responses Elicited by Forelimb- and Photo-stimulation in Channelrhodopsin-2 Mice: Insights into the Hemodynamic Point Spread Function

    PubMed Central

    Vazquez, Alberto L.; Fukuda, Mitsuhiro; Crowley, Justin C.; Kim, Seong-Gi

    2014-01-01

    Hemodynamic responses are commonly used to map brain activity; however, their spatial limits have remained unclear because of the lack of a well-defined and malleable spatial stimulus. To examine the properties of neural activity and hemodynamic responses, multiunit activity, local field potential, cerebral blood volume (CBV)-sensitive optical imaging, and laser Doppler flowmetry were measured from the somatosensory cortex of transgenic mice expressing Channelrhodopsin-2 in cortex Layer 5 pyramidal neurons. The magnitude and extent of neural and hemodynamic responses were modulated using different photo-stimulation parameters and compared with those induced by somatosensory stimulation. Photo-stimulation-evoked spiking activity across cortical layers was similar to forelimb stimulation, although their activity originated in different layers. Hemodynamic responses induced by forelimb- and photo-stimulation were similar in magnitude and shape, although the former were slightly larger in amplitude and wider in extent. Altogether, the neurovascular relationship differed between these 2 stimulation pathways, but photo-stimulation-evoked changes in neural and hemodynamic activities were linearly correlated. Hemodynamic point spread functions were estimated from the photo-stimulation data and its full-width at half-maximum ranged between 103 and 175 µm. Therefore, submillimeter functional structures separated by a few hundred micrometers may be resolved using hemodynamic methods, such as optical imaging and functional magnetic resonance imaging. PMID:23761666

  18. A comparative study of fluoride ingestion levels, serum thyroid hormone & TSH level derangements, dental fluorosis status among school children from endemic and non-endemic fluorosis areas.

    PubMed

    Singh, Navneet; Verma, Kanika Gupta; Verma, Pradhuman; Sidhu, Gagandeep Kaur; Sachdeva, Suresh

    2014-01-03

    The study was undertaken to determine serum/urinary fluoride status and comparison of free T4, free T3 and thyroid stimulating hormone levels of 8 to 15 years old children with and without dental fluorosis living in an endemic and non-endemic fluorosis area. A sample group of 60 male and female school children, with or without dental fluorosis, consuming fluoride-contaminated water in endemic fluoride area of Udaipur district, Rajasthan were selected through a school dental fluorosis survey. The sample of 10 children of same age and socio-economic status residing in non endemic areas who did not have dental fluorosis form controls. Fluoride determination in drinking water, urine and blood was done with Ion 85 Ion Analyzer Radiometer with Hall et al. method. The thyroid gland functional test was done by Immonu Chemiluminiscence Micropartical Assay with Bayer Centaur Autoanalyzer. The significantly altered FT3, FT4 and TSH hormones level in both group1A and 1B school children were noted. The serum and urine fluoride levels were found to be increased in both the groups. A significant relationship of water fluoride to urine and serum fluoride concentration was seen. The serum fluoride concentration also had significant relationship with thyroid hormone (FT3/FT4) and TSH concentrations. The testing of drinking water and body fluids for fluoride content, along with FT3, FT4, and TSH in children with dental fluorosis is desirable for recognizing underlying thyroid derangements and its impact on fluorosis.

  19. In Vitro Evaluation of an Alternative Neonatal Extracorporeal Life Support Circuit on Hemodynamic Performance and Bubble Trap.

    PubMed

    Spencer, Shannon B; Wang, Shigang; Woitas, Karl; Glass, Kristen; Kunselman, Allen R; Ündar, Akif

    2017-01-01

    The objective of this study was to evaluate an alternative neonatal extracorporeal life support (ECLS) circuit with a RotaFlow centrifugal pump and Better-Bladder (BB) for hemodynamic performance and gaseous microemboli (GME) capture in a simulated neonatal ECLS system. The circuit consisted of a Maquet RotaFlow centrifugal pump, a Quadrox-iD Pediatric diffusion membrane oxygenator, 8 Fr arterial cannula, and 10 Fr venous cannula. A "Y" connector was inserted into the venous line to allow for comparison between BB and no BB. The circuit and pseudopatient were primed with lactated Ringer's solution and packed human red blood cells (hematocrit 35%). All hemodynamic trials were conducted at flow rates ranging from 100 to 600 mL/min at 36°C. Real-time pressure and flow data were recorded using a data acquisition system. For GME testing, 0.5 cc of air was injected via syringe into the venous line. GME were detected and characterized with or without the BB using the Emboli Detection and Classification Quantifier (EDAC) System. Trials were conducted at flow rates ranging from 200 to 500 mL/min. The hemodynamic energy data showed that up to 75.2% of the total hemodynamic energy was lost from the circuit. The greatest pressure drops occurred across the arterial cannula and increased with increasing flow rate from 10.1 mm Hg at 100 mL/min to 114.3 mm Hg at 600 mL/min. The EDAC results showed that the BB trapped a significant amount of the GME in the circuit. When the bladder was removed, GME passed through the pump head and the oxygenator to the arterial line. This study showed that a RotaFlow centrifugal pump combined with a BB can help to significantly decrease the number of GME in a neonatal ECLS circuit. Even with this optimized alternative circuit, a large percentage of the total hemodynamic energy was lost. The arterial cannula was the main source of resistance in the circuit.

  20. Primary hypertension in children and adolescents is an immuno-metabolic disease with hemodynamic consequences.

    PubMed

    Litwin, Mieczysław; Michałkiewicz, Jacek; Gackowska, Lidia

    2013-08-01

    With the rise in obesity epidemic primary hypertension (PH) is now one of the most common chronic diseases in adolescence. In contrast to hypertensive adults, hypertensive children usually are not exposed to other comorbidities such as diabetes, chronic kidney disease and atherosclerosis. Thus, PH in children and adolescents can be treated as the early stage of development of cardiovascular disease. There is increasing amount of data indicating that PH is not only hemodynamic phenomenon but a complex syndrome involving disturbed activity of sympathetic nervous system, metabolic abnormalities and activation of innate and adaptive immune system. We discuss results of the studies on clinical, metabolic and immunological phenotype of hypertensive children, associations between metabolic and immunological abnormalities with target organ damage and results of antihypertensive treatment.

  1. 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

  2. Axial penile rigidity: determinants and relation to hemodynamic parameters.

    PubMed

    Goldstein, I; Udelson, D

    1998-05-01

    Erectile dysfunction may be defined in terms of axial penile rigidity, the physical property that enables the erection to be utilized as a penetration tool during sexual activity. Erectile dysfunction occurs when inadequate axial penile rigidity results in buckling of the penile column when subjected to axial compressive loading situations during vaginal intromission. New multi-disciplinary engineering studies of penile hemodynamic and structural dynamic relationships are reviewed concerning the determinants of axial penile rigidity. Axial penile rigidity develops as a continuum during the increases in intracavernosal pressure and volume changes from the flaccid state and is influenced by intracavernosal pressure, penile tissue mechanical properties and penile geometry. Two penile tissue mechanical properties are especially relevant; cavernosal maximum volume at relatively low intracavernosal pressure, and tunical distensibility, the relative volume of the fully erect to completely flaccid pendulous penis. Two penile geometric properties are critical; the penile aspect ratio, defined as the diameter to length ratio of the pendulous penis, and the magnitude of the flaccid penile diameter. Clinically measured values of axial buckling forces in patients undergoing dynamic pharmacocavernosometry strongly correlated to theoretic-based analytic derived magnitudes of axial penile rigidity based on these above pressure, tissue and geometric determinants. Since axial penile rigidity is not exclusively dependent upon intracavernosal pressure, patients with normal erectile hemodynamics may be erroneously labelled as having psychogenic dysfunction where their true pathophysiology may be related to abnormal penile tissue properties and/or penile geometric factors. Similarly, some patients may claim sufficient rigidity for penetration, but have abnormal hemodynamic erectile function studies. They may have uniquely advantageous tissue mechanical and/or geometric properties. More

  3. 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

  4. 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

  5. Functional Imaging of the Hemodynamic Sensory Gating Response in Schizophrenia

    PubMed Central

    Mayer, Andrew R.; Ruhl, David; Merideth, Flannery; Ling, Josef; Hanlon, Faith; Bustillo, Juan; Cañive, Jose

    2013-01-01

    The cortical (auditory and prefrontal) and/or subcortical (thalamic and hippocampal) generators of abnormal electrophysiological responses during sensory gating remain actively debated in the schizophrenia literature. Functional magnetic resonance imaging (fMRI) has the spatial resolution for disambiguating deep or simultaneous sources but has been relatively under-utilized to investigate generators of the gating response. Thirty patients with chronic schizophrenia (SP) and 30 matched controls participated in the current experiment. Hemodynamic response functions (HRF) for single (S1) and pairs (S1 + S2) of identical (IT; “gating-out” redundant information) or non-identical (NT; “gating-in” novel information) tones were generated through deconvolution. Increased or prolonged activation for patients in conjunction with deactivation for controls was observed within auditory cortex, prefrontal cortex and thalamus in response to single tones during the late hemodynamic response, and these group differences were not associated with clinical or cognitive symptomatology. Although patient hyper-activation to paired-tones conditions was present in several ROI, the effects were not statistically significant for either the gating-out or gating-in conditions. Finally, abnormalities in the post-undershoot of the auditory HRF were also observed for both single and paired tones conditions in patients. In conclusion, the amalgamation of the entire electrophysiological response to both S1 and S2 stimuli may limit hemodynamic sensitivity to paired tones during sensory gating, which may be more readily overcome by paradigms that utilize multiple stimuli rather than pairs. Patient hyperactivation following single tones is suggestive of deficits in basic inhibition, neurovascular abnormalities or a combination of both factors. PMID:22461278

  6. 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.

  7. Hemodynamic effects of mebutamate in spontaneously hypertensive rats.

    PubMed

    Pfeffer, J M; Pfeffer, M A; Frohlich, E D

    1975-05-01

    The acute hemodynamic effects of the antihypertensive agent mebutamate were evaluated in spontaneously hypertensive and normotensive Wistar rats. Arterial and venous pressures and cardiac output (electromagnetic flowmeter) were recorded in artificially ventilated, open-chest, ether-anesthetized animals before and after varying doses of mebutamate were injected intravenously. In both normotensive and hypertensive rats mebutamate produced a moderate decrease in arterial pressure which was associated with a reduction in both heart rate and cardiac output; total peripheral resistance remained unchanged. These data suggest that mebutamate may have therapuetic value in reducing arterial pressure in mild to moderately severe hypertensive patients.

  8. Hemodynamic support with percutaneous devices in patients with heart failure.

    PubMed

    Kapur, Navin K; Esposito, Michele

    2015-04-01

    The use of surgically implanted durable mechanical circulatory support (MCS) in high-risk patients with heart failure is declining and short-term, nondurable MCS device use is growing. Percutaneously delivered MCS options for advanced heart failure include the intra-aortic balloon pump, Impella axial flow catheter, TandemHeart centrifugal pump, and venoarterial extracorporeal membrane oxygenation. Nondurable MCS devices have unique implantation characteristics and hemodynamic effects. Algorithms and guidelines for optimal nondurable MCS device selection do not exist. Emerging technologies and applications will address the need for improved left ventricular unloading using lower-profile devices, longer-term ambulatory support, and the potential for myocardial recovery.

  9. 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.

  10. Mathematical modeling of renal hemodynamics in physiology and pathophysiology.

    PubMed

    Sgouralis, Ioannis; Layton, Anita T

    2015-06-01

    In addition to the excretion of metabolic waste and toxin, the kidney plays an indispensable role in regulating the balance of water, electrolyte, acid-base, and blood pressure. For the kidney to maintain proper functions, hemodynamic control is crucial. In this review, we describe representative mathematical models that have been developed to better understand the kidney's autoregulatory processes. We consider mathematical models that simulate glomerular filtration, and renal blood flow regulation by means of the myogenic response and tubuloglomerular feedback. We discuss the extent to which these modeling efforts have expanded the understanding of renal functions in health and disease.

  11. [Constraints on the knee caused by meniscal and ligament derangement. Study of the internal condylotibial joint. Experimental cinematic method].

    PubMed

    Frain, P; Fontaine, C; D'Hondt, D

    1984-01-01

    In a previous paper the authors have demonstrated that the polycentric curve of the surface of the medial condyle of the femur is a logarithmic spiral arch whose centre is the point of attachment of the medial ligament. In the present study, the totality of the menisco-ligamentous system was considered and studied on cadavers following a geometric model. It is shown that the ligament system controls combined or successive movements of gliding or rotation of the condyle on the tibial plateau in such a way as to avoid any cam effect or additional strain. Division of ligaments or excision of a meniscus leads to an increase in strain which varies in relation to the type of lesion. The increase is moderate after division of the anterior cruciate ligament, greater after division of the posterior cruciate ligament and severe after meniscectomy especially when associated with ligamentous division.

  12. 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

  13. Hemodynamic aspects of normal human feto-placental (umbilical) circulation.

    PubMed

    Acharya, Ganesh; Sonesson, Sven-Erik; Flo, Kari; Räsänen, Juha; Odibo, Anthony

    2016-06-01

    Understanding the changes in normal circulatory dynamics that occur during the course of pregnancy is essential for improving our knowledge of pathophysiological mechanisms associated with feto-placental diseases. The umbilical circulation is the lifeline of the fetus, and it is accessible for noninvasive assessment. However, not all hemodynamic parameters can be reliably measured in utero using currently available technology. Experimental animal studies have been crucial in validating major concepts related to feto-placental circulatory physiology, but caution is required in directly translating the findings of such studies into humans due to species differences. Furthermore, it is important to establish normal reference ranges and take into account gestational age associated changes while interpreting the results of clinical investigation. Therefore, it is necessary to critically evaluate, synthesize and summarize the knowledge available from the studies performed on human pregnancies to be able to appropriately apply them in clinical practice. This narrative review is an attempt to present contemporary concepts on hemodynamics of feto-placental circulation based on human studies.

  14. Optimal design for nonlinear estimation of the hemodynamic response function.

    PubMed

    Maus, Bärbel; van Breukelen, Gerard J P; Goebel, Rainer; Berger, Martijn P F

    2012-06-01

    Subject-specific hemodynamic response functions (HRFs) have been recommended to capture variation in the form of the hemodynamic response between subjects (Aguirre et al., [ 1998]: Neuroimage 8:360-369). The purpose of this article is to find optimal designs for estimation of subject-specific parameters for the double gamma HRF. As the double gamma function is a nonlinear function of its parameters, optimal design theory for nonlinear models is employed in this article. The double gamma function is linearized by a Taylor approximation and the maximin criterion is used to handle dependency of the D-optimal design on the expansion point of the Taylor approximation. A realistic range of double gamma HRF parameters is used for the expansion point of the Taylor approximation. Furthermore, a genetic algorithm (GA) (Kao et al., [ 2009]: Neuroimage 44:849-856) is applied to find locally optimal designs for the different expansion points and the maximin design chosen from the locally optimal designs is compared to maximin designs obtained by m-sequences, blocked designs, designs with constant interstimulus interval (ISI) and random event-related designs. The maximin design obtained by the GA is most efficient. Random event-related designs chosen from several generated designs and m-sequences have a high efficiency, while blocked designs and designs with a constant ISI have a low efficiency compared to the maximin GA design.

  15. Neuronal or hemodynamic? Grappling with the functional MRI signal.

    PubMed

    Bandettini, Peter A

    2014-09-01

    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.

  16. Coronary Flow Impacts Aortic Leaflet Mechanics and Aortic Sinus Hemodynamics.

    PubMed

    Moore, Brandon L; Dasi, Lakshmi Prasad

    2015-09-01

    Mechanical stresses on aortic valve leaflets are well-known mediators for initiating processes leading to calcific aortic valve disease. Given that non-coronary leaflets calcify first, it may be hypothesized that coronary flow originating from the ostia significantly influences aortic leaflet mechanics and sinus hemodynamics. High resolution time-resolved particle image velocimetry (PIV) measurements were conducted to map the spatiotemporal characteristics of aortic sinus blood flow and leaflet motion with and without physiological coronary flow in a well-controlled in vitro setup. The in vitro setup consists of a porcine aortic valve mounted in a physiological aorta sinus chamber with dynamically controlled coronary resistance to emulate physiological coronary flow. Results were analyzed using qualitative streak plots illustrating the spatiotemporal complexity of blood flow patterns, and quantitative velocity vector and shear stress contour plots to show differences in the mechanical environments between the coronary and non-coronary sinuses. It is shown that the presence of coronary flow pulls the classical sinus vorticity deeper into the sinus and increases flow velocity near the leaflet base. This creates a beneficial increase in shear stress and washout near the leaflet that is not seen in the non-coronary sinus. Further, leaflet opens approximately 10% farther into the sinus with coronary flow case indicating superior valve opening area. The presence of coronary flow significantly improves leaflet mechanics and sinus hemodynamics in a manner that would reduce low wall shear stress conditions while improving washout at the base of the leaflet.

  17. 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.

  18. Antiangiogenic factors and maternal hemodynamics during intensive hemodialysis in pregnancy.

    PubMed

    Cornelis, Tom; Spaanderman, Marc; Beerenhout, Charles; Perschel, Frank H; Verlohren, Stefan; Schalkwijk, Casper G; van der Sande, Frank M; Kooman, Jeroen P; Hladunewich, Michelle

    2013-10-01

    We report on a 21-year-old pregnant patient with IgA nephropathy who was initiated on intensive hemodialysis (8 hours of hemodialysis 3 times a week) at a gestational age of 26 weeks on the basis of worsening kidney function resulting in rapidly progressive fatigue and difficulties in metabolic control. Throughout the pregnancy, and while on intensive hemodialysis, 24-hour ambulatory blood pressure control was within the target, and results of weekly 24-hour measurement of central hemodynamics and pulse wave velocity, and of serial levels of circulating (anti-)angiogenic factors were comparable to normal pregnancies. Estimated fetal growth evolved along the 50th percentile, and no polyhydramnios was detected. After induction for a sudden, unexplained increase in blood pressure, she delivered a healthy boy of 2480 g at a gestational age of 36 weeks. This case adds to the expanding literature that supports the use of intensive hemodialysis in pregnant patients with end-stage renal disease and illustrates, for the first time, the potential use of serial (anti-) angiogenic factors and 24-hour measurements of blood pressure and hemodynamic indices in order to facilitate monitoring of these complicated patients.

  19. 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.

  20. Cardiovascular and hemodynamic effects of glucagon-like peptide-1.

    PubMed

    Goodwill, Adam G; Mather, Kieren J; Conteh, Abass M; Sassoon, Daniel J; Noblet, Jillian N; Tune, Johnathan D

    2014-09-01

    Glucagon-like peptide-1 (GLP-1) is an incretin hormone that has been shown to have hemodynamic and cardioprotective capacity in addition to its better characterized glucoregulatory actions. Because of this, emerging research has focused on the ability of GLP-1 based therapies to drive myocardial substrate selection, enhance cardiac performance and regulate heart rate, blood pressure and vascular tone. These studies have produced consistent and reproducible results amongst numerous laboratories. However, there are obvious disparities in findings obtained in small animal models versus those of higher mammals. This species dependent discrepancy calls to question, the translational value of individual findings. Moreover, few studies of GLP-1 mediated cardiovascular action have been performed in the presence of a pre-existing comorbidities (e.g. obesity/diabetes) which limits interpretation of the effectiveness of incretin-based therapies in the setting of disease. This review addresses cardiovascular and hemodynamic potential of GLP-1 based therapies with attention to species specific effects as well as the interaction between therapies and disease.

  1. A novel periodic boundary condition for computational hemodynamics studies.

    PubMed

    Bahramian, Fereshteh; Mohammadi, Hadi

    2014-07-01

    In computational fluid dynamics models for hemodynamics applications, boundary conditions remain one of the major issues in obtaining accurate fluid flow predictions. For major cardiovascular models, the realistic boundary conditions are not available. In order to address this issue, the whole computational domain needs to be modeled, which is practically impossible. For simulating fully developed turbulent flows using the large eddy simulation and dynamic numerical solution methods, which are very popular in hemodynamics studies, periodic boundary conditions are suitable. This is mainly because the computational domain can be reduced considerably. In this study, a novel periodic boundary condition is proposed, which is based on mass flow condition. The proposed boundary condition is applied on a square duct for the sake of validation. The mass-based condition was shown to obtain the solution in 15% less time. As such, the mass-based condition has two decisive advantages: first, the solution for a given Reynolds number can be obtained in a single simulation because of the direct specification of the mass flow, and second, simulations can be made more quickly.

  2. 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).

  3. [Hemodynamic correction in children with severe traumatic injuries by the means of transpulmonary hemodilution].

    PubMed

    Lekmanov, A U; Azovskiĭ, D K; Piliutnik, S F; Gegueva, E N

    2011-01-01

    The purpose of the research is t objectify the indications for use of catecholamines and/or change of the infusion therapy volume based on transpulmonary thermodilution in children with severe traumatic injuries. The examined group consisted of 22 children with thermal concomitant or isolated trauma and drowning. All the patents were transferred to the Intensive Care Unit from other hospitals. Hemodynamic parameter estimation was based upon transpulmonary thermodilution. Results indicate, that based upon dynamic assessment of cardiac output, preload (global end diastolic volume index) and postload (systemic vascular resistance index) it is possible to carry out an early targeted correction of the fluid therapy and chose the right type of inotorpic support. Transpulmonary thermodilution in children with severe traumatic injuries allows achieving optimal parameters of blood circulation just 24 hours after its adaption.

  4. Prefrontal hemodynamic activity predicts false memory--a near-infrared spectroscopy study.

    PubMed

    Kubota, Yasutaka; Toichi, Motomi; Shimizu, Mitsue; Mason, Richard A; Findling, Robert L; Yamamoto, Kokichi; Calabrese, Joseph R

    2006-07-15

    Evidence from lesion studies suggests an important role of the prefrontal cortex (PFC) in the reconstructive processes of episodic memory or memory distortion. Results from functional imaging studies imply PFC involvement during the illusionary recollection of non-experienced events. Here, we used a two-channel near-infrared spectroscopy (NIRS) system and conducted real-time monitoring of PFC hemodynamics, while subjects studied word lists and subsequently recognized unstudied items (false recognition). Bilateral increases in the oxygenated hemoglobin concentration ([oxy-Hb]) were observed during false recognition compared to true recognition, and a left PFC dominant increase of [oxy-Hb] was observed during encoding phases where subjects later claimed that they recognized unstudied words. Traces of semantic processing, reflected primarily in the left PFC activity, could eventually predict whether subjects falsely recognize non-experienced events.

  5. Storage of Fractional Flow Reserve Hemodynamic Waveforms Using Semantic Extension of the DICOM Standard.

    PubMed

    Kakouros, Nikolaos

    2016-06-01

    Visual assessment of coronary stenoses by coronary angiography remains widely used but correlates poorly with ischemia, particularly for moderate lesions. Fractional flow reserve (FFR) is a cardiac catheterization procedure that aims to provide objective measures of coronary lesion hemodynamic significance and involves the acquisition of phasic pressure and electrocardiographic waveforms. The dataset from these procedures currently remains in proprietary systems with restricted data access, inability for data exchange, and often inadequate archiving. Digital Imaging and Communications in Medicine (DICOM) includes a waveform information object definition. We describe the method of encapsulating FFR procedural information into a DICOM waveform file. We define private data elements to capture modality-specific data that is not represented by standard DICOM data elements. We propose the adoption of this semantic extension of the DICOM waveform information object for exchange and archiving of data from studies of pressure-derived indices of coronary stenoses.

  6. The cerebral hemodynamics of normotensive hypovolemia during lower-body negative pressure

    NASA Technical Reports Server (NTRS)

    Giller, C. A.; Levine, B. D.; Meyer, Y.; Buckey, J. C.; Lane, L. D.; Borchers, D. J.

    1992-01-01

    Although severe hypovolemia can lead to hypotension and neurological decline, many patients with neurosurgical disorders experience a significant hypovolemia while autonomic compensatory mechanisms maintain a normal blood pressure. To assess the effects of normotensive hypovolemia upon cerebral hemodynamics, transcranial Doppler ultrasound monitoring of 13 healthy volunteers was performed during graded lower-body negative pressure of up to -50 mm Hg, an accepted laboratory model for reproducing the physiological effects of hypovolemia. Middle cerebral artery flow velocity declined by 16% +/- 4% (mean +/- standard error of the mean) and the ratio between transcranial Doppler ultrasound pulsatility and systemic pulsatility rose 22% +/- 8%, suggesting cerebral small-vessel vasoconstriction in response to the sympathetic activation unmasked by lower-body negative pressure. This vasoconstriction may interfere with the autoregulatory response to a sudden fall in blood pressure, and may explain the common observation of neurological deficit during hypovolemia even with a normal blood pressure.

  7. [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.

  8. Wet BNP, fluid and hemodynamic status at discharge in acute heart failure.

    PubMed

    Parrinello, Gaspare; Torres, Daniele; Paterna, Salvatore; Di Pasquale, Pietro; Licata, Giuseppe

    2010-11-19

    We comment the noteworthy results of Pimenta et al. concerning the significance of discharge BNP levels in acute HF patients. The innovation of Pimento's study is the systematic research of the potential relationship between BNP and clinical and hemodynamic parameters. We focused the attention on the importance of wet "BNP" in managing HF and its ability to reflect congestion and multiple underlying patho-physiological disturbances. The first observation, regarding the statistical order, underlines the importance of renal insufficiency at discharge in genesis of higher BNP levels. Secondly, we note that the relationship between natriuretic peptides and the non-invasive measurement of the fluid status assessed by bioelectrical impedance analysis was already demonstrated. Thirdly, we comment on the potential therapeutical implication of the verified relationship between BNP and albumin levels and we argue on the clinical utility of the albumin supplementation or hypertonic solutions in unstable HF management due to their oncotic power. Fourthly, we wish to further examine the role of central volemia. We underline that some studies had demonstrated that systemic congestion may be a mirror of central congestion and may also influence these levels alone in acute and also chronic HF patients. We believe that a concealed or poorly-assessed accumulation of systemic fluid is of crucial importance in managing HF, which frequently remains undiagnosed or inappropriately treated, thus requiring recurrent hospital readmission and disease progression. Furthermore not only BNP at discharge but also bioimpedance detection may be helpful to discover misdiagnosed congestion. We are of the opinion that, in cases of hospitalized HF and thereafter in ambulatory setting, the achievement and, then, maintenance of dry-wet tailoring diuretics, fluid and sodium intake is the key approach leading to a euvolemic status, a lowering of the NYHA class and an improvement in cardiac hemodynamics

  9. Noninvasive monitoring hemodynamic responses in RIF tumors during and after PDT

    NASA Astrophysics Data System (ADS)

    Yu, Guoqiang; Durduran, Turgut; Busch, Theresa M.; Wang, Hsing-Wen; Zhou, Chao; Saunders, H. Mark; Sehgal, Chandra M.; Yodh, Arjun G.

    2003-06-01

    Changes in blood flow and oxygenation during and after PDT provide information about tumor vessel and cellular damage. The characterization of these changes may improve our understanding of PDT mechanisms and help predict treatment efficacy. We have designed a hybrid system that can non-invasively measure in vivo hemodynamic changes and provide independent information about tumor oxygenation and blood flow. Diffuse correlation spectroscopy (DCS) monitors blood flow by measuring the optical phase shifts caused by moving blood cells, while diffuse photon density wave (DPDW) spectroscopy measures tissue absorption and scattering. When mounted on a camera, our unique probe allows non-contact measurements that avoid compressing the tumor and altering blood flow. An optical filter mounted in front of the camera lens cut off light below 650nm, which allowed monitoring of blood flow during PDT. The utility of the hybrid system was demonstrated by monitoring the hemodynamic changes during and after PDT in mice bearing the experimental radiation-induced fibrosarcoma (RIF). For the first time, we non-invasively and continually monitored the in vivo flow changes during PDT. Relative oxygen consumption was calculated using flow values measured by DCS and oxygenation measured by a broadband absorption spectrometer. During PDT an initial rapid increase in blood flow was found, followed by a decrease and slow recovery. After PDT, substantial and continued reductions in blood saturation, blood flow and oxygen consumption were found after 3 hours, suggesting that permanent damage to tumor cells and blood vessels had occurred. The comparison of flow values after PDT as measured by DCS and by Power Doppler ultrasound (CWFA) demonstrated that both techniques non-invasively detected similar global changes in tumor blood flow or perfusion after PDT.

  10. Hemodynamic disturbances in premature infants born after chorioamnionitis: association with cord blood cytokine concentrations.

    PubMed

    Yanowitz, Toby Debra; Jordan, Jeanne Ann; Gilmour, Carol Huntress; Towbin, Richard; Bowen, A'Delbert; Roberts, James Michael; Brozanski, Beverly Sobchak

    2002-03-01

    Chorioamnionitis and elevated cord blood inflammatory cytokine concentrations are associated with detectable disturbances of systemic and cerebral hemodynamics in premature newborns. Fifty-five infants (25-31 wk gestation) were enrolled. Chorioamnionitis was defined by placental histology. IL-6, IL-1beta, and tumor necrosis factor-alpha were quantified by ELISA. Blood pressure, heart rate, cardiac output, stroke volume, fractional shortening, and middle cerebral artery blood flow velocities were measured at 3 +/- 1 h after birth. Chorioamnionitis was evident in 22 placentas and was associated with increased IL-6 (p < 0.001), IL-1beta (p = 0.035), and heart rate (p = 0.027); and with decreased mean and diastolic blood pressure (p = 0.026 and p = 0.019, respectively). IL-6 concentration correlated inversely with systolic, mean, and diastolic blood pressures. Right ventricular cardiac output was elevated (p = 0.028) in infants with fetal vessel inflammation. Maternal temperature >or=38.0 degrees C and newborn immature-to-total white blood cell ratio >or=0.4 were associated with significant decreases in left ventricular fractional shortening (p = 0.001 and p = 0.005, respectively). Neither chorioamnionitis nor elevated cytokine concentrations were associated with changes in middle cerebral artery Doppler blood flow velocities. Chorioamnionitis and elevated cord blood IL-6 concentrations are associated with decreased blood pressure in premature newborns. Inflammation of the fetal vessels and nonspecific indicators of infection are associated with disturbances in cardiac function. Infants with chorioamnionitis and elevated cytokine concentrations do not manifest changes in cerebral Doppler indices within the first few postnatal hours. We speculate that cytokine-associated systemic hemodynamic disturbances in premature infants born after chorioamnionitis predispose such infants to perinatal brain injury.

  11. Loss of Toll-Like Receptor 4 Function Partially Protects against Peripheral and Cardiac Glucose Metabolic Derangements During a Long-Term High-Fat Diet

    PubMed Central

    Jackson, Ellen E.; Rendina-Ruedy, Elisabeth; Smith, Brenda J.; Lacombe, Veronique A.

    2015-01-01

    Diabetes is a chronic inflammatory disease that carries a high risk of cardiovascular disease. However, the pathophysiological link between these disorders is not well known. We hypothesize that TLR4 signaling mediates high fat diet (HFD)-induced peripheral and cardiac glucose metabolic derangements. Mice with a loss-of-function mutation in TLR4 (C3H/HeJ) and age-matched control (C57BL/6) mice were fed either a high-fat diet or normal diet for 16 weeks. Glucose tolerance and plasma insulin were measured. Protein expression of glucose transporters (GLUT), AKT (phosphorylated and total), and proinflammatory cytokines (IL-6, TNF-α and SOCS-3) were quantified in the heart using Western Blotting. Both groups fed a long-term HFD had increased body weight, blood glucose and insulin levels, as well as impaired glucose tolerance compared to mice fed a normal diet. TLR4-mutant mice were partially protected against long-term HFD-induced insulin resistance. In control mice, feeding a HFD decreased cardiac crude membrane GLUT4 protein content, which was partially rescued in TLR4-mutant mice. TLR4-mutant mice fed a HFD also had increased expression of GLUT8, a novel isoform, compared to mice fed a normal diet. GLUT8 content was positively correlated with SOCS-3 and IL-6 expression in the heart. No significant differences in cytokine expression were observed between groups, suggesting a lack of inflammation in the heart following a HFD. Loss of TLR4 function partially restored a healthy metabolic phenotype, suggesting that TLR4 signaling is a key mechanism in HFD-induced peripheral and cardiac insulin resistance. Our data further suggest that TLR4 exerts its detrimental metabolic effects in the myocardium through a cytokine-independent pathway. PMID:26539824

  12. Extracellular brain pH with or without hypoxia is a marker of profound metabolic derangement and increased mortality after traumatic brain injury.

    PubMed

    Timofeev, Ivan; Nortje, Jurgens; Al-Rawi, Pippa G; Hutchinson, Peter J A; Gupta, Arun K

    2013-03-01

    Cerebral hypoxia and acidosis can follow traumatic brain injury (TBI) and are associated with increased mortality. This study aimed to evaluate a relationship between reduced pH(bt) and disturbances of cerebral metabolism. Prospective data from 56 patients with TBI, receiving microdialysis and Neurotrend monitoring, were analyzed. Four tissue states were defined based on pH(bt) and P(bt)O(2): 1--low P(bt)O(2)/pH(bt), 2--low pH(bt)/normal P(bt)O(2), 3--normal pH(bt)/low P(bt)O(2), and 4--normal pH(bt)/P(bt)O(2)). Microdialysis values were compared between the groups. The relationship between P(bt)O(2) and lactate/pyruvate (LP) ratio was evaluated at different pH(bt) levels. Proportional contribution of each state was evaluated against mortality. As compared with the state 4, the state 3 was not different, the state 2 exhibited higher levels of lactate, LP, and glucose and the state 1--higher LP and reduced glucose (P<0.001). A significant negative correlation between LP and P(bt)O(2) (rho=-0.159, P<0.001) was stronger at low pH(bt) (rho=-0.201, P<0.001) and nonsignificant at normal pH(bt) (P=0.993). The state 2 was a significant discriminator of mortality categories (P=0.031). Decreased pH(bt) is associated with impaired metabolism. Measuring pH(bt) with P(bt)O(2) is a more robust way of detecting metabolic derangements.

  13. Loss of Toll-Like Receptor 4 Function Partially Protects against Peripheral and Cardiac Glucose Metabolic Derangements During a Long-Term High-Fat Diet.

    PubMed

    Jackson, Ellen E; Rendina-Ruedy, Elisabeth; Smith, Brenda J; Lacombe, Veronique A

    2015-01-01

    Diabetes is a chronic inflammatory disease that carries a high risk of cardiovascular disease. However, the pathophysiological link between these disorders is not well known. We hypothesize that TLR4 signaling mediates high fat diet (HFD)-induced peripheral and cardiac glucose metabolic derangements. Mice with a loss-of-function mutation in TLR4 (C3H/HeJ) and age-matched control (C57BL/6) mice were fed either a high-fat diet or normal diet for 16 weeks. Glucose tolerance and plasma insulin were measured. Protein expression of glucose transporters (GLUT), AKT (phosphorylated and total), and proinflammatory cytokines (IL-6, TNF-α and SOCS-3) were quantified in the heart using Western Blotting. Both groups fed a long-term HFD had increased body weight, blood glucose and insulin levels, as well as impaired glucose tolerance compared to mice fed a normal diet. TLR4-mutant mice were partially protected against long-term HFD-induced insulin resistance. In control mice, feeding a HFD decreased cardiac crude membrane GLUT4 protein content, which was partially rescued in TLR4-mutant mice. TLR4-mutant mice fed a HFD also had increased expression of GLUT8, a novel isoform, compared to mice fed a normal diet. GLUT8 content was positively correlated with SOCS-3 and IL-6 expression in the heart. No significant differences in cytokine expression were observed between groups, suggesting a lack of inflammation in the heart following a HFD. Loss of TLR4 function partially restored a healthy metabolic phenotype, suggesting that TLR4 signaling is a key mechanism in HFD-induced peripheral and cardiac insulin resistance. Our data further suggest that TLR4 exerts its detrimental metabolic effects in the myocardium through a cytokine-independent pathway.

  14. Extracellular brain pH with or without hypoxia is a marker of profound metabolic derangement and increased mortality after traumatic brain injury

    PubMed Central

    Timofeev, Ivan; Nortje, Jurgens; Al-Rawi, Pippa G; Hutchinson, Peter JA; Gupta, Arun K

    2013-01-01

    Cerebral hypoxia and acidosis can follow traumatic brain injury (TBI) and are associated with increased mortality. This study aimed to evaluate a relationship between reduced pHbt and disturbances of cerebral metabolism. Prospective data from 56 patients with TBI, receiving microdialysis and Neurotrend monitoring, were analyzed. Four tissue states were defined based on pHbt and PbtO2: 1—low PbtO2/pHbt, 2—low pHbt/normal PbtO2, 3—normal pHbt/low PbtO2, and 4—normal pHbt/PbtO2). Microdialysis values were compared between the groups. The relationship between PbtO2 and lactate/pyruvate (LP) ratio was evaluated at different pHbt levels. Proportional contribution of each state was evaluated against mortality. As compared with the state 4, the state 3 was not different, the state 2 exhibited higher levels of lactate, LP, and glucose and the state 1—higher LP and reduced glucose (P<0.001). A significant negative correlation between LP and PbtO2 (rho=−0.159, P<0.001) was stronger at low pHbt (rho=−0.201, P<0.001) and nonsignificant at normal pHbt (P=0.993). The state 2 was a significant discriminator of mortality categories (P=0.031). Decreased pHbt is associated with impaired metabolism. Measuring pHbt with PbtO2 is a more robust way of detecting metabolic derangements. PMID:23232949

  15. Verification of a research prototype for hemodynamic analysis of cerebral aneurysms.

    PubMed

    Suzuki, Takashi; Ioan Nita, Cosmin; Rapaka, Saikiran; Takao, Hiroyuki; Mihalef, Viorel; Fujimura, Soichiro; Dahmani, Chihebeddine; Sharma, Puneet; Mamori, Hiroya; Ishibashi, Toshihiro; Redel, Thomas; Yamamoto, Makoto; Murayama, Yuichi

    2016-08-01

    Owing to its clinical importance, there has been a growing body of research on understanding the hemodynamics of cerebral aneurysms. Traditionally, this work has been performed using general-purpose, state-of-the-art commercial solvers. This has meant requiring engineering expertise for making appropriate choices on the geometric discretization, time-step selection, choice of boundary conditions etc. Recently, a CFD research prototype has been developed (Siemens Healthcare GmbH, Prototype - not for diagnostic use) for end-to-end analysis of aneurysm hemodynamics. This prototype enables anatomical model preparation, hemodynamic computations, advanced visualizations and quantitative analysis capabilities. In this study, we investigate the accuracy of the hemodynamic solver in the prototype against a commercially available CFD solver ANSYS CFX 16.0 (ANSYS Inc., Canonsburg, PA, www.ansys.com) retrospectively on a sample of twenty patient-derived aneurysm models, and show good agreement of hemodynamic parameters of interest.

  16. First implantable hemodynamic monitoring device placement in single ventricle fontan anatomy.

    PubMed

    Bradley, Elisa A; Berman, Darren; Daniels, Curt J

    2016-08-01

    The Fontan anatomy leads to elevated central venous pressure along with chronic venous congestion and low cardiac output; this is felt to be responsible for deterioration of exercise tolerance and functional capacity over time. Real-time hemodynamic evaluation of the Fontan anatomy has not been evaluated until now. Here, we report the technical aspects of the first two adult Fontan patients to undergo placement of an invasive hemodynamic monitor (IHM). We validate IHM readings with invasive pulmonary artery catheter derived hemodynamics in the Fontan and show successful home transmission of pulmonary artery hemodynamic tracings. This technology has the capacity to change current understanding of Fontan hemodynamics and treatment in patients with complex single-ventricle anatomy. © 2016 Wiley Periodicals, Inc.

  17. Lack of Chemokine Signaling through CXCR5 Causes Increased Mortality, Ventricular Dilatation and Deranged Matrix during Cardiac Pressure Overload

    PubMed Central

    Waehre, Anne; Husberg, Cathrine; Sjaastad, Ivar; Nygård, Ståle; Dahl, Christen P.; Ahmed, M. Shakil; Finsen, Alexandra V.; Reims, Henrik; Louch, William E.; Hilfiker-Kleiner, Denise; Vinge, Leif E.; Roald, Borghild; Attramadal, Håvard; Lipp, Martin; Gullestad, Lars; Aukrust, Pål; Christensen, Geir

    2011-01-01

    Rationale Inflammatory mechanisms have been suggested to play a role in the development of heart failure (HF), but a role for chemokines is largely unknown. Based on their role in inflammation and matrix remodeling in other tissues, we hypothesized that CXCL13 and CXCR5 could be involved in cardiac remodeling during HF. Objective We sought to analyze the role of the chemokine CXCL13 and its receptor CXCR5 in cardiac pathophysiology leading to HF. Methods and Results Mice harboring a systemic knockout of the CXCR5 (CXCR5−/−) displayed increased mortality during a follow-up of 80 days after aortic banding (AB). Following three weeks of AB, CXCR5−/− developed significant left ventricular (LV) dilatation compared to wild type (WT) mice. Microarray analysis revealed altered expression of several small leucine-rich proteoglycans (SLRPs) that bind to collagen and modulate fibril assembly. Protein levels of fibromodulin, decorin and lumican (all SLRPs) were significantly reduced in AB CXCR5−/− compared to AB WT mice. Electron microscopy revealed loosely packed extracellular matrix with individual collagen fibers and small networks of proteoglycans in AB CXCR5−/− mice. Addition of CXCL13 to cultured cardiac fibroblasts enhanced the expression of SLRPs. In patients with HF, we observed increased myocardial levels of CXCR5 and SLRPs, which was reversed following LV assist device treatment. Conclusions Lack of CXCR5 leads to LV dilatation and increased mortality during pressure overload, possibly via lack of an increase in SLRPs. This study demonstrates a critical role of the chemokine CXCL13 and CXCR5 in survival and maintaining of cardiac structure upon pressure overload, by regulating proteoglycans essential for correct collagen assembly. PMID:21533157

  18. The innervation of the kidney in renal injury and inflammation: A cause and consequence of deranged cardiovascular control.

    PubMed

    Abdulla, Mohammed H; Johns, Edward J

    2017-02-09

    Extensive investigations have revealed that renal sympathetic nerves regulate renin secretion, tubular fluid reabsorption and renal haemodynamics which can impact on cardiovascular homoeostasis normally and in pathophysiological states. The significance of the renal afferent innervation and its role in determining the autonomic control of the cardiovascular system is uncertain. The transduction pathways at the renal afferent nerves have been shown to require pro-inflammatory mediators and TRPV1 channels. Reno-renal reflexes have been described, both inhibitory and excitatory, demonstrating that a neural link exists between kidneys and may determine the distribution of excretory and haemodynamic function between the two kidneys. The impact of renal afferent nerve activity on basal and reflex regulation of global sympathetic drive remains opaque. There is clinical and experimental evidence that in states of chronic kidney disease and renal injury there is infiltration of T-helper cells with a sympatho-excitation and blunting of the high and low pressure baroreceptor reflexes regulating renal sympathetic nerve activity. The baroreceptor deficits are renal nerve-dependent as the dysregulation can be relieved by renal denervation. There is also experimental evidence that in obese states there is a sympatho-excitation and disrupted baroreflex regulation of renal sympathetic nerve activity which is mediated by the renal innervation. This body of information provides an important basis for directing greater attention to the role of renal injury/inflammation causing an inappropriate activation of the renal afferent nerves as an important initiator of aberrant autonomic cardiovascular control. This article is protected by copyright. All rights reserved.

  19. Hemodynamic response to treatment of iron deficiency anemia in pulmonary arterial hypertension: longitudinal insights from an implantable hemodynamic monitor

    PubMed Central

    2016-01-01

    Abstract Despite new therapeutic options, pulmonary arterial hypertension (PAH) remains a progressive disease associated with substantial morbidity and mortality. As such, additional strategies for monitoring and adjunctive management of this disease are important. A 59-year-old woman with scleroderma-associated PAH received an implantable hemodynamic monitor (IHM) as part of a research protocol at our institution. Pulmonary artery pressures, heart rate, and cardiac output (sensor-based algorithm) were measured on a daily basis, and parameters of right ventricular (RV) performance and afterload were calculated. At the time of IHM implant, the patient had functional class III symptoms, was receiving triple-drug therapy, and had normal hemoglobin levels. Four months after implant, and with further optimization of prostacyclin therapy, she had improvement in her symptoms. However, shortly thereafter, while the patient was receiving stable drug therapy, her case regressed with worsening symptoms, and the patient received a new diagnosis of iron deficiency anemia. Oral iron supplementation resulted in normalization of hemoglobin levels and improvement in the patient’s iron profile. A gradual and sustained reduction in pulmonary pressures was noted after initiation of oral iron accompanied by increased RV performance and favorable reduction in RV afterload. The patient had significant symptomatic improvement. Iron deficiency is an underappreciated yet easily treatable risk factor in PAH. Use of IHM in this case longitudinally illustrates the optimization of pulmonary hemodynamics and RV afterload in tandem with clinical improvement achieved by a simple therapy. PMID:28090307

  20. Hemodynamic response to treatment of iron deficiency anemia in pulmonary arterial hypertension: longitudinal insights from an implantable hemodynamic monitor.

    PubMed

    Mehmood, Muddassir; Agarwal, Richa; Raina, Amresh; Correa-Jaque, Priscilla; Benza, Raymond L

    2016-12-01

    Despite new therapeutic options, pulmonary arterial hypertension (PAH) remains a progressive disease associated with substantial morbidity and mortality. As such, additional strategies for monitoring and adjunctive management of this disease are important. A 59-year-old woman with scleroderma-associated PAH received an implantable hemodynamic monitor (IHM) as part of a research protocol at our institution. Pulmonary artery pressures, heart rate, and cardiac output (sensor-based algorithm) were measured on a daily basis, and parameters of right ventricular (RV) performance and afterload were calculated. At the time of IHM implant, the patient had functional class III symptoms, was receiving triple-drug therapy, and had normal hemoglobin levels. Four months after implant, and with further optimization of prostacyclin therapy, she had improvement in her symptoms. However, shortly thereafter, while the patient was receiving stable drug therapy, her case regressed with worsening symptoms, and the patient received a new diagnosis of iron deficiency anemia. Oral iron supplementation resulted in normalization of hemoglobin levels and improvement in the patient's iron profile. A gradual and sustained reduction in pulmonary pressures was noted after initiation of oral iron accompanied by increased RV performance and favorable reduction in RV afterload. The patient had significant symptomatic improvement. Iron deficiency is an underappreciated yet easily treatable risk factor in PAH. Use of IHM in this case longitudinally illustrates the optimization of pulmonary hemodynamics and RV afterload in tandem with clinical improvement achieved by a simple therapy.

  1. Resting-state hemodynamics are spatiotemporally coupled to synchronized and symmetric neural activity in excitatory neurons

    PubMed Central

    Ma, Ying; Shaik, Mohammed A.; Kozberg, Mariel G.; Portes, Jacob P.; Timerman, Dmitriy

    2016-01-01

    Brain hemodynamics serve as a proxy for neural activity in a range of noninvasive neuroimaging techniques including functional magnetic resonance imaging (fMRI). In resting-state fMRI, hemodynamic fluctuations have been found to exhibit patterns of bilateral synchrony, with correlated regions inferred to have functional connectivity. However, the relationship between resting-state hemodynamics and underlying neural activity has not been well established, making the neural underpinnings of functional connectivity networks unclear. In this study, neural activity and hemodynamics were recorded simultaneously over the bilateral cortex of awake and anesthetized Thy1-GCaMP mice using wide-field optical mapping. Neural activity was visualized via selective expression of the calcium-sensitive fluorophore GCaMP in layer 2/3 and 5 excitatory neurons. Characteristic patterns of resting-state hemodynamics were accompanied by more rapidly changing bilateral patterns of resting-state neural activity. Spatiotemporal hemodynamics could be modeled by convolving this neural activity with hemodynamic response functions derived through both deconvolution and gamma-variate fitting. Simultaneous imaging and electrophysiology confirmed that Thy1-GCaMP signals are well-predicted by multiunit activity. Neurovascular coupling between resting-state neural activity and hemodynamics was robust and fast in awake animals, whereas coupling in urethane-anesthetized animals was slower, and in some cases included lower-frequency (<0.04 Hz) hemodynamic fluctuations that were not well-predicted by local Thy1-GCaMP recordings. These results support that resting-state hemodynamics in the awake and anesthetized brain are coupled to underlying patterns of excitatory neural activity. The patterns of bilaterally-symmetric spontaneous neural activity revealed by wide-field Thy1-GCaMP imaging may depict the neural foundation of functional connectivity networks detected in resting-state fMRI. PMID:27974609

  2. Resting-state hemodynamics are spatiotemporally coupled to synchronized and symmetric neural activity in excitatory neurons.

    PubMed

    Ma, Ying; Shaik, Mohammed A; Kozberg, Mariel G; Kim, Sharon H; Portes, Jacob P; Timerman, Dmitriy; Hillman, Elizabeth M C

    2016-12-27

    Brain hemodynamics serve as a proxy for neural activity in a range of noninvasive neuroimaging techniques including functional magnetic resonance imaging (fMRI). In resting-state fMRI, hemodynamic fluctuations have been found to exhibit patterns of bilateral synchrony, with correlated regions inferred to have functional connectivity. However, the relationship between resting-state hemodynamics and underlying neural activity has not been well established, making the neural underpinnings of functional connectivity networks unclear. In this study, neural activity and hemodynamics were recorded simultaneously over the bilateral cortex of awake and anesthetized Thy1-GCaMP mice using wide-field optical mapping. Neural activity was visualized via selective expression of the calcium-sensitive fluorophore GCaMP in layer 2/3 and 5 excitatory neurons. Characteristic patterns of resting-state hemodynamics were accompanied by more rapidly changing bilateral patterns of resting-state neural activity. Spatiotemporal hemodynamics could be modeled by convolving this neural activity with hemodynamic response functions derived through both deconvolution and gamma-variate fitting. Simultaneous imaging and electrophysiology confirmed that Thy1-GCaMP signals are well-predicted by multiunit activity. Neurovascular coupling between resting-state neural activity and hemodynamics was robust and fast in awake animals, whereas coupling in urethane-anesthetized animals was slower, and in some cases included lower-frequency (<0.04 Hz) hemodynamic fluctuations that were not well-predicted by local Thy1-GCaMP recordings. These results support that resting-state hemodynamics in the awake and anesthetized brain are coupled to underlying patterns of excitatory neural activity. The patterns of bilaterally-symmetric spontaneous neural activity revealed by wide-field Thy1-GCaMP imaging may depict the neural foundation of functional connectivity networks detected in resting-state fMRI.

  3. 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

  4. Growth and hemodynamics after early embryonic aortic arch occlusion.

    PubMed

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

    2015-08-01

    The majority of severe clinically significant forms of congenital heart disease (CHD) are 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. Here, we combine computational fluid dynamics (CFD) simulations with in vivo experiments to test how individual pharyngeal arch artery hemodynamics alter as a result of local interventions obstructing 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 h. 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

  5. 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

  6. Hemodynamic measurements in rat brain and human muscle using diffuse near-infrared absorption and correlation spectroscopies

    NASA Astrophysics Data System (ADS)

    Yu, Guoqiang; Durduran, Turgut; Furuya, D.; Lech, G.; Zhou, Chao; Chance, Britten; Greenberg, J. H.; Yodh, Arjun G.

    2003-07-01

    Measurement of concentration, oxygenation, and flow characteristics of blood cells can reveal information about tissue metabolism and functional heterogeneity. An improved multifunctional hybrid system has been built on the basis of our previous hybrid instrument that combines two near-infrared diffuse optical techniques to simultaneously monitor the changes of blood flow, total hemoglobin concentration (THC) and blood oxygen saturation (StO2). Diffuse correlation spectroscopy (DCS) monitors blood flow (BF) by measuring the optical phase shifts caused by moving blood cells, while diffuse photon density wave spectroscopy (DPDW) measures tissue absorption and scattering. Higher spatial resolution, higher data acquisition rate and higher dynamic range of the improved system allow us to monitor rapid hemodynamic changes in rat brain and human muscles. We have designed two probes with different source-detector pairs and different separations for the two types of experiments. A unique non-contact probe mounted on the back of a camera, which allows continuous measurements without altering the blood flow, was employed to in vivo monitor the metabolic responses in rat brain during KCl induced cortical spreading depression (CSD). A contact probe was used to measure changes of blood flow and oxygenation in human muscle during and after cuff occlusion or exercise, where the non-contact probe is not appropriate for monitoring the moving target. The experimental results indicate that our multifunctional hybrid system is capable of in vivo and non-invasive monitoring of the hemodynamic changes in different tissues (smaller tissues in rat brain, larger tissues in human muscle) under different conditions (static versus moving). The time series images of flow during CSD obtained by our technique revealed spatial and temporal hemodynamic changes in rat brain. Two to three fold longer recovery times of flow and oxygenation after cuff occlusion or exercise from calf flexors in a

  7. Building a Better Neonatal Extracorporeal Life Support Circuit: Comparison of Hemodynamic Performance and Gaseous Microemboli Handling in Different Pump and Oxygenator Technologies.

    PubMed

    Glass, Kristen; Trivedi, Payal; Wang, Shigang; Woitas, Karl; Kunselman, Allen R; Ündar, Akif

    2017-04-01

    Neurologic complications during neonatal extracorporeal life support (ECLS) are associated with significant morbidity and mortality. Gaseous microemboli (GME) in the ECLS circuit may be a possible cause. Advances in neonatal circuitry may improve hemodynamic performance and GME handling leading to reduction in patient complications. This study compared hemodynamic performance and GME handling using two centrifugal pumps (Maquet RotaFlow and Medos Deltastream DP3) and polymethylpentene oxygenators (Maquet Quadrox-iD and Medos Hilite 800LT) in a neonatal ECLS circuit model. The experimental circuit was primed with Lactated Ringer's solution and packed human red blood cells (hematocrit 40%) and arranged in parallel with the RotaFlow and DP3 pump, Quadrox-iD and Hilite oxygenator, and Better-Bladder. Hemodynamic trials evaluating pressure drops and total hemodynamic energy (THE) were conducted at 300 and 500 mL/min at 36°C. GME handling was measured after 0.5 mL of air was injected into the venous line using the Emboli Detection and Classification Quantifier System with unique pump, oxygenator, and Better-Bladder combinations. The RotaFlow pump and Quadrox oxygenator arrangement had lower pressure drops and THE loss at both flow rates compared to the DP3 pump and Hilite oxygenator (P < 0.01). Total GME volume and counts decreased with Better-Bladder at both flow rates with all combinations (P < 0.01). Hemodynamic performance and energy loss were similar in all of the circuit combinations. The Better-Bladder significantly decreased GME. All four combinations of pumps and oxygenators also performed similarly in terms of GME handling.

  8. Evaluation of the hemodynamics in straight 6-mm and tapered 6- to 8-mm grafts as upper arm hemodialysis vascular access.

    PubMed

    Sarmast, M; Niroomand-Oscuii, H; Ghalichi, F; Samiei, E

    2014-09-01

    The present study is intended to investigate and compare the hemodynamics in two different sizes of hemodialysis arteriovenous grafts for upper arm hemodialysis vascular access: 8-mm tapered to 6-mm at the arterial side and straight 6 mm. A computational simulation approach is presented for this study, which is validated against the available experimental and numerical pressure measurements in the literature. The imposed boundary conditions at the arterial inlet and venous outlet boundaries of the models are physiological velocity and pressure waveforms, respectively. Blood flow fields and distribution patterns of the hemodynamic indices including wall shear stress (WSS) as one of the major hemodynamic parameters of the cardiovascular system and spatial wall shear stress gradient (SWSSG) as an indicator of disturbed flow patterns and hence susceptible sites of lesion developments are analyzed and compared between the two grafts. The tapered 6- to 8-mm graft seemingly is associated with less disturbed flow patterns within the venous anastomosis (VA) and the vein downstream while benefiting from higher blood flow rates within. Also, it shows a definitive advantage in terms of WSS and SWSSG distribution patterns around the VA and throughout the vein downstream with significantly lower values, which reduce the risk of thrombosis formation and stenotic lesion developments. The only disadvantage encountered in using 6- to 8-mm tapered graft is higher values of hemodynamic parameters at the arterial junction attributable to its significantly higher mean blood flow rate within. The results clearly indicate that the tapered 6- to 8-mm graft entirely outperforms straight 6-mm graft hemodynamically as an upper arm hemodialysis vascular access graft and confirms clinical data in the literature, which suggests advantageous use of tapered 6- to 8-mm grafts in the creation of upper arm brachioaxillary hemodialysis vascular access grafts in selected groups of patients with

  9. Hemodynamic effects of intra-aortic balloon counterpulsation in patients with acute myocardial infarction complicated by cardiogenic shock: the prospective, randomized IABP shock trial.

    PubMed

    Prondzinsky, Roland; Unverzagt, Susanne; Russ, Martin; Lemm, Henning; Swyter, Michael; Wegener, Nikolas; Buerke, Ute; Raaz, Uwe; Ebelt, Henning; Schlitt, Axel; Heinroth, Konstantin; Haerting, Johannes; Werdan, Karl; Buerke, Michael

    2012-04-01

    We conducted the IABP Cardiogenic Shock Trial (ClinicalTrials.gov ID NCT00469248) as a prospective, randomized, monocentric clinical trial to determine the hemodynamic effects of additional intra-aortic balloon pump (IABP) treatment and its effects on severity of disease in patients with acute myocardial infarction complicated by cardiogenic shock (CS). Intra-aortic balloon pump counterpulsation is recommended in patients with CS complicating myocardial infarction. However, there are only limited randomized controlled trial data available supporting the efficacy of IABP following percutaneous coronary intervention (PCI) and its impact on hemodynamic parameters in patients with CS. Percutaneous coronary intervention of infarct-related artery was performed in 40 patients with acute myocardial infarction complicated by CS, within 12 h of onset of hemodynamic instability. Serial hemodynamic parameters were determined over the next 4 days and compared in patients receiving medical treatment alone with those treated with additional intra-aortic balloon counterpulsation. There were no significant differences among severity of disease (i.e., Acute Physiology and Chronic Health Evaluation II score) initially and no differences among both groups for disease improvement. We observed significant temporal improvements of cardiac output (4.8 ± 0.5 to 6.0 ± 0.5 L/min), systemic vascular resistance (926 ± 73 to 769 ± 101 dyn · s(-1) · cm(-5)), and the prognosis-validated cardiac power output (0.78 ± 0.06 to 1.01 ± 0.2 W) within the IABP group. However, there were no significant differences between the IABP group and the medical-alone group. Additional IABP treatment did not result in a significant hemodynamic improvement compared with medical therapy alone in a randomized prospective trial in patients with CS following PCI. Therefore, the use and recommendation for IABP treatment in CS remain unclear.

  10. WEB downloadable software for training in cardiovascular hemodynamics in the (3-D) stress echo lab

    PubMed Central

    2010-01-01

    When a physiological (exercise) stress echo is scheduled, interest focuses on wall motion segmental contraction abnormalities to diagnose ischemic response to stress, and on left ventricular ejection fraction to assess contractile reserve. Echocardiographic evaluation of volumes (plus standard assessment of heart rate and blood pressure) is ideally suited for the quantitative and accurate calculation of a set of parameters allowing a complete characterization of cardiovascular hemodynamics (including cardiac output and systemic vascular resistance), left ventricular elastance (mirroring left ventricular contractility, theoretically independent of preload and afterload changes heavily affecting the ejection fraction), arterial elastance, ventricular arterial coupling (a central determinant of net cardiovascular performance in normal and pathological conditions), and diastolic function (through the diastolic mean filling rate). All these parameters were previously inaccessible, inaccurate or labor-intensive and now become, at least in principle, available in the stress echocardiography laboratory since all of them need an accurate estimation of left ventricular volumes and stroke volume, easily derived from 3 D echo. Aims of this paper are: 1) to propose a simple method to assess a set of parameters allowing a complete characterization of cardiovascular hemodynamics in the stress echo lab, from basic measurements to calculations 2) to propose a simple, web-based software program, to learn and training calculations as a phantom of the everyday activity in the busy stress echo lab 3) to show examples of software testing in a way that proves its value. The informatics infrastructure is available on the web, linking to http://cctrainer.ifc.cnr.it PMID:21073738

  11. Chemotherapeutic (cyclophosphamide) effects on rat breast tumor hemodynamics monitored by multi-channel NIRS

    NASA Astrophysics Data System (ADS)

    Kim, Jae G.; Zhao, Dawen; Mason, Ralph P.; Liu, Hanli

    2005-04-01

    We previously suggested that the two time constants quantified from the increase of tumor oxyhemoglobin concentration, ▵ [HbO2], during hyperoxic gas intervention are associated with two blood flow/perfusion rates in well perfused and poorly perfused regions of tumors. In this study, our hypothesis is that when cancer therapy is applied to a tumor, changes in blood perfusion will occur and be detected by the NIRS. For experiments, systemic chemotherapy, cyclophosphamide (CTX), was applied to two groups of rats bearing syngeneic 13762NF mammary adenocarcinomas: one group received a single high dose i. p. (200 mg/kg CTX) and the other group continuous low doses (20 mg/kg CTX i. p. for 10 days). Time courses of changes in tumor ▵ [HbO2] were measured at four different locations on the breast tumors non-invasively with an inhaled gas sequence of air-oxygen-air before and after CTX administration. Both rat body weight and tumor volume decreased after administration of high dose CTX, but continuous low doses showed decrease of tumor volume only. Baselines (without any therapy) intra- and inter-tumor heterogeneity of vascular oxygenation during oxygen inhalation were similar to our previous observations. After CTX treatment, significant changes in vascular hemodynamic response to oxygen inhalation were observed from both groups. By fitting the increase of ▵ [HbO2] during oxygen inhalation, we have obtained changes of vascular structure ratio and also of perfusion rate ratio before and after chemotherapy. The preliminary results suggest that cyclophosphamide has greatest effect on the well perfused tumor vasculature. Overall, our study supports our earlier hypothesis, proving that the effects of chemotherapy in tumor may be monitored non-invasively by using NIRS to detect changes of hemodynamics induced with respiratory challenges.

  12. Pyruvate stabilizes electrocardiographic and hemodynamic function in pigs recovering from cardiac arrest.

    PubMed

    Cherry, Brandon H; Nguyen, Anh Q; Hollrah, Roger A; Williams, Arthur G; Hoxha, Besim; Olivencia-Yurvati, Albert H; Mallet, Robert T

    2015-12-01

    Cardiac electromechanical dysfunction may compromise recovery of patients who are initially resuscitated from cardiac arrest, and effective treatments remain elusive. Pyruvate, a natural intermediary metabolite, energy substrate, and antioxidant, has been found to protect the heart from ischemia-reperfusion injury. This study tested the hypothesis that pyruvate-enriched resuscitation restores hemodynamic, metabolic, and electrolyte homeostasis following cardiac arrest. Forty-two Yorkshire swine underwent pacing-induced ventricular fibrillation and, after 6 min pre-intervention arrest, 4 min precordial compressions followed by transthoracic countershocks. After defibrillation and recovery of spontaneous circulation, the pigs were monitored for another 4 h. Sodium pyruvate or NaCl were infused i.v. (0.1 mmol·kg(-1)·min(-1)) throughout precordial compressions and the first 60 min recovery. In 8 of the 24 NaCl-infused swine, the first countershock converted ventricular fibrillation to pulseless electrical activity unresponsive to subsequent countershocks, but only 1 of 18 pyruvate-treated swine developed pulseless electrical activity (relative risk 0.17; 95% confidence interval 0.13-0.22). Pyruvate treatment also lowered the dosage of vasoconstrictor phenylephrine required to maintain systemic arterial pressure at 15-60 min recovery, hastened clearance of excess glucose, elevated arterial bicarbonate, and raised arterial pH; these statistically significant effects persisted up to 3 h after sodium pyruvate infusion, while infusion-induced hypernatremia subsided. These results demonstrate that pyruvate-enriched resuscitation achieves electrocardiographic and hemodynamic stability in swine during the initial recovery from cardiac arrest. Such metabolically based treatment may offer an effective strategy to support cardiac electromechanical recovery immediately after cardiac arrest.

  13. Effects of benidipine on glomerular hemodynamics and proteinuria in patients with nondiabetic nephropathy.

    PubMed

    Morikawa, Takashi; Okumura, Michiaki; Konishi, Yoshio; Okada, Noriyuki; Imanishi, Masahito

    2002-07-01

    Experimental studies suggest that some long-acting calcium antagonists decrease glomerular hypertension and suppress the progression of nephropathy, but clinical evidence is lacking. To investigate clinically whether a long-acting calcium antagonist, benidipine, lowers glomerular capillary hydraulic pressure via a decrease in efferent arteriolar resistance and decreases proteinuria, we examined hypertensive patients with nondiabetic nephropathy. The subjects were 7 patients with chronic glomerulonephritis or glomerulosclerosis. Before and during the administration of benidipine (4 mg/day), systemic pressure, glomerular hemodynamics, the sodium sensitivity index (reciprocal of the pressure-natriuresis curve), and urinary excretion of proteins (total protein, albumin, and immunoglobulin G) were investigated. The glomerular hemodynamics in terms of glomerular capillary hydraulic pressure and resistance of afferent and efferent arterioles were calculated from the renal clearance, plasma total protein concentration, and pressure-natriuresis relationship. Benidipine lowered the mean arterial pressure from 105 +/-5 to 99 +/- 4 mm Hg (p = 0.002; mean +/- SD) and glomerular pressure from 48 +/- 8 to 39 +/- 5 mmHg (p = 0.006) by decreasing the resistance of efferent arterioles. Benidipine made the pressure-natriuresis curve steeper and decreased the median sodium sensitivity index from 0.099 (0.084 and 0.117; 25th and 75th percentiles) to 0.048 (0.017 and 0.058; p = 0.018). Urinary excretion of proteins did not change. Our clinical study showed that benidipine lowered the glomerular pressure by decreasing the resistance of efferent arterioles and decreased the sodium sensitivity of blood pressure, but did not affect proteinuria in patients with nondiabetic nephropathy.

  14. [Study of the effect of colloidal solution of silver nanoparticles on parameters of cardio- and hemo-dynamics in rabbits].

    PubMed

    Pryskoka, A O

    2014-01-01

    Metal nanoparticles and silver nanoparticles in particular are extensively studied recently considering their prominent antimicrobial properties. Nevertheless, their toxicity aspects and probable side effects remain not well studied. In this article the results of study of the influence of silver nanoparticles onto a cardiovascular system in an in vivo experiment were provided, changes in parameters of cardio- and hemodynamics were defined, and the principles of such influence were identified. Dose-dependent effect of these nanoparticles was established when administered in dose of 4.3 mg/kg three times and 20 mg/kg once.

  15. Short separation regression improves statistical significance and better localizes the hemodynamic response obtained by near-infrared spectroscopy for tasks with differing autonomic responses

    PubMed Central

    Yücel, Meryem A.; Selb, Juliette; Aasted, Christopher M.; Petkov, Mike P.; Becerra, Lino; Borsook, David; Boas, David A.

    2015-01-01

    Abstract. Autonomic nervous system response is known to be highly task-dependent. The sensitivity of near-infrared spectroscopy (NIRS) measurements to superficial layers, particularly to the scalp, makes it highly susceptible to systemic physiological changes. Thus, one critical step in NIRS data processing is to remove the contribution of superficial layers to the NIRS signal and to obtain the actual brain response. This can be achieved using short separation channels that are sensitive only to the hemodynamics in the scalp. We investigated the contribution of hemodynamic fluctuations due to autonomous nervous system activation during various tasks. Our results provide clear demonstrations of the critical role of using short separation channels in NIRS measurements to disentangle differing autonomic responses from the brain activation signal of interest. PMID:26835480

  16. [Hemodynamic types of hypertensive disease according to echocardiographic data].

    PubMed

    Zamotaev, I P; Dechko, E P

    1978-11-01

    Central hemodynamics was studied by means of echocardiography in 7 patients suffering from neurocirculatory dystonia with a high cardiac index but normal arterial pressure, and in 41 patients with essential hypertension prior to, and after treatment. Two groups of patients suffering from essential hypertension were distinguished: with a hyperkinetic type of circulation and with a normal cardiac index. In the first group there was a statistically significant increase in the stroke index and the index of diastolic left ventricular diameter with a normal ejection fraction. The increase in the cardiac index in the hyperkinetic type of essential hypertension is caused by an increase in the stroke output according to the Frank--Starling law. The authors believe that the increase in peripheral resistance is the principal pathogenetic mechanism of hypertension with any level of the minute volume.

  17. Asymptomatic Pulmonary Vein Stenosis: Hemodynamic Adaptation and Successful Ablation

    PubMed Central

    Weinberg, Denis

    2016-01-01

    Pulmonary vein stenosis is a well-established possible complication following an atrial fibrillation ablation of pulmonary veins. Symptoms of pulmonary vein stenosis range from asymptomatic to severe exertional dyspnea. The number of asymptomatic patients with pulmonary vein stenosis is greater than originally estimated; moreover, only about 22% of severe pulmonary vein stenosis requires intervention. We present a patient with severe postatrial fibrillation (AF) ablation pulmonary vein (PV) stenosis, which was seen on multiple imaging modalities including cardiac computed tomography (CT) angiogram, lung perfusion scan, and pulmonary angiogram. This patient did not have any pulmonary symptoms. Hemodynamic changes within a stenosed pulmonary vein might not reflect the clinical severity of the obstruction if redistribution of pulmonary artery flow occurs. Our patient had an abnormal lung perfusion and ventilation (V/Q) scan, suggesting pulmonary artery blood flow redistribution. The patient ultimately underwent safe repeat atrial fibrillation ablation with successful elimination of arrhythmia. PMID:28105376

  18. Hemodynamic changes in post-suspension rats during gradual hemorrhage

    NASA Astrophysics Data System (ADS)

    Vinogradova, O. L.; Borovik, A. S.; Tsvirkoun, D. V.; Tarasova, O. S.

    2005-08-01

    In urethane-anasthetized rats the effects of 2-week tail suspension upon the hemodynamic changes during simulated orthostatism and during loss of blood were studied. Baseline values of mean arterial pressure (MAP) and pulse interval (PI) did not differ in cage control (C) and post-suspension rats (TS). In both groups 45o head-up tilt resulted in prominent decline of MAP. In C group this effect was followed by the compensatory phase, which was virtually lost in TS group. No significant postural changes of PI were observed. Gradual hemorrhage (30% blood loss during 30 min) resulted in similar MAP drop in C and TS (up to 40% of baseline level). Along with that, PI increase was less prominent in TS (25%) compared to C (60%) indicating higher resistance of the heart to hypovolemia after suspension.

  19. Portal hypertension in vinyl chloride monomer workers. A hemodynamic study.

    PubMed

    Blendis, L M; Smith, P M; Lawrie, B W; Stephens, M R; Evans, W D

    1978-08-01

    Hemodynamic studies were performed in 5 vinyl chloride monomer workers in whom splenomegaly or thrombocytopenia was detected during a screening program at major chemical plant. Three patients had portal hypertension and collateral venous circulations, with intrasplenic pressures between 20 and 29 mm Hg and normal wedged hepatic venous pressures, but the gradient between the wedged and free hepatic vein pressures was also increased. Splenic blood flows were increased in both hypertensive and normotensive patients. There was no correlation between the splenic blood flow and the portal pressure or the presence of portal fibrosis. The portal hypertension associated with vinyl chloride exposure is mainly presinusoidal in type, and may be attributed to an abnormality of the portal vein radicles, or hepatic sinusoids.

  20. 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

  1. Vascular development and hemodynamic force in the mouse yolk sac

    PubMed Central

    Garcia, Monica D.; Larina, Irina V.

    2014-01-01

    Vascular remodeling of the mouse embryonic yolk sac is a highly dynamic process dependent on multiple genetic signaling pathways as well as biomechanical factors regulating proliferation, differentiation, migration, cell-cell, and cell-matrix interactions. During this early developmental window, the initial primitive vascular network of the yolk sac undergoes a dynamic remodeling process concurrent with the onset of blood flow, in which endothelial cells establish a branched, hierarchical structure of large vessels and smaller capillary beds. In this review, we will describe the molecular and biomechanical regulators which guide vascular remodeling in the mouse embryonic yolk sac, as well as live imaging methods for characterizing endothelial cell and hemodynamic function in cultured embryos. PMID:25191274

  2. Effects of cardiac motion on right coronary artery hemodynamics.

    PubMed

    Zeng, Dehong; Ding, Zhaohua; Friedman, Morton H; Ethier, C Ross

    2003-04-01

    The purpose of this work was to investigate the effects of physiologically realistic cardiac-induced motion on hemodynamics in human right coronary arteries. The blood flow patterns were numerically simulated in a modeled right coronary artery (RCA) having a uniform circular cross section of 2.48 mm diam. Arterial motion was specified based on biplane cineangiograms, and incorporated physiologically realistic bending and torsion. Simulations were carried out with steady and pulsatile inflow conditions (mean ReD=233, alpha=1.82) in both fixed and moving RCA models, to evaluate the relative importance of RCA motion, flow pulsation, and the interaction between motion and flow pulsation. RCA motion with a steady inlet flow rate caused variations in wall shear stress (WSS) magnitude up to 150% of the inlet Poiseuille value. There was significant spatial variability in the magnitude of this motion-induced WSS variation. However, the time-averaged WSS distribution was similar to that predicted in a static model representing the time-averaged geometry. Furthermore, the effects of flow pulsatility dominated RCA motion-induced effects; specifically, there were only modest differences in the WSS history between simulations conducted in fixed and moving RCA models with pulsatile inflow. RCA motion has little effect on time-averaged WSS patterns. It has a larger effect on the temporal variation of WSS, but even this effect is overshadowed by the variations in WSS due to flow pulsation. The hemodynamic effects of RCA motion can, therefore, be ignored as a first approximation in modeling studies.

  3. Tempol improves renal hemodynamics and pressure natriuresis in hyperthyroid rats.

    PubMed

    Moreno, Juan Manuel; Rodríguez Gómez, Isabel; Wangensteen, Rosemary; Alvarez-Guerra, Miriam; de Dios Luna, Juan; García-Estañ, Joaquín; Vargas, Félix

    2008-03-01

    Hyperthyroidism in rats is associated with increased oxidative stress. These animals also show abnormal renal hemodynamics and an attenuated pressure-diuresis-natriuresis (PDN) response. We analyzed the role of oxidative stress as a mediator of these alterations by examining acute effects of tempol, a superoxide dismutase mimetic. The effects of increasing bolus doses of tempol (25-150 micromol/kg) on mean arterial pressure (MAP), renal vascular resistance (RVR), and cortical (CBF) and medullary (MBF) blood flow were studied in control and thyroxine (T4)-treated rats. In another experiment, tempol was infused at 150 micromol.kg(-1).h(-1) to analyze its effects on the glomerular filtration rate (GFR) and on PDN response in these animals. Tempol dose dependently decreased MAP and RVR and increased CBF and MBF in control and T4-treated rats, but the T4 group showed a greater responsiveness to tempol in all of these variables. The highest dose of tempol decreased RVR by 13.5 +/- 2.1 and 5.5 +/- 1.2 mmHg.ml(-1).min(-1) in hyperthyroid (P < 0.01) and control rats, respectively. GFR was not changed by tempol in controls but was significantly increased in the hyperthyroid group. Tempol did not change the absolute or fractional PDN responses of controls but significantly improved those of hyperthyroid rats, although without attaining normal values. Tempol increased the slopes of the relationship between renal perfusion pressure and natriuresis (T4+tempol: 0.17 +/- 0.05; T4: 0.09 +/- 0.03 microeq.min(-1).g(-1).mmHg(-1); P < 0.05) and reduced 8-isoprostane excretion in hyperthyroid rats. These results show that antioxidant treatment with tempol improves renal hemodynamic variables and PDN response in hyperthyroid rats, indicating the participation of an increased oxidative stress in these mechanisms.

  4. 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

  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. Hemodynamic changes by drug interaction of adrenaline with chlorpromazine.

    PubMed

    Higuchi, Hitoshi; Yabuki, Akiko; Ishii-Maruhama, Minako; Tomoyasu, Yumiko; Maeda, Shigeru; Miyawaki, Takuya

    2014-01-01

    Adrenaline (epinephrine) is included in dental local anesthesia for the purpose of vasoconstriction. In Japan, adrenaline is contraindicated for use in patients receiving antipsychotic therapy, because the combination of adrenaline and an antipsychotic is considered to cause severe hypotension; however, there is insufficient evidence supporting this claim. The purpose of the present study was to clarify the changes in hemodynamics caused by drug interaction between adrenaline and an antipsychotic and to evaluate the safety of the combined use of adrenaline and an antipsychotic in an animal study. Male Sprague-Dawley rats were anesthetized with sodium pentobarbital. A catheter was inserted into the femoral artery to measure blood pressure and pulse rate. Rats were pretreated by intraperitoneal injection of chlorpromazine or chlorpromazine and propranolol, and after 20 minutes, saline or 1 of 3 different doses of adrenaline was administered by intraperitoneal injection. Changes in the ratio of mean arterial blood pressure and pulse rate were measured after the injection of adrenaline. Significant hypotension and tachycardia were observed after the injection of adrenaline in the chlorpromazine-pretreated rats. These effects were in a dose-dependent manner, and 100 μg/kg adrenaline induced significant hemodynamic changes. Furthermore, in the chlorpromazine and propranolol-pretreated rats, modest hypertension was induced by adrenaline, but hypotension and tachycardia were not significantly shown. Hypotension was caused by a drug interaction between adrenaline and chlorpromazine through the activation of the β-adrenergic receptor and showed a dose-dependent effect. Low-dose adrenaline similar to what might be used in human dental treatment did not result in a significant homodynamic change.

  7. 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.

  8. 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

  9. 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

  10. 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

  11. Investigation of cerebral hemodynamics and collateralization in asymptomatic carotid stenoses.

    PubMed

    AlMuhanna, Khalid; Zhao, Limin; Kowalewski, Gregory; Beach, Kirk W; Lal, Brajesh K; Sikdar, Siddhartha

    2012-01-01

    Stroke is the second leading cause of death in the world, and one of the major causes of disability. Approximately 30% of ischemic strokes are due to plaque rupture in the carotid arteries. The most popular diagnostic method uses Doppler ultrasound to find the percent stenosis. However, other factors, such as the hemodynamics around the plaque may play a larger role in identifying the risk of plaque rupture. It has been shown previously in simulations that non-collateral flow in the circle of Willis (COW) could cause an increase of the intraluminal velocity around carotid plaque. This added strain may increase the vulnerability of the plaque to rupture. We investigated asymmetries in flow waveforms in the middle cerebral artery (MCA) in asymptomatic patients with carotid artery stenosis. We compared clinical results of velocity waveforms in the MCA, acquired using transcranial Doppler (TCD), with a simple linear simulation model of the intra- and extracranial arterial network to investigate the relationship between contralateral and ipsilateral flow profiles in the MCA for patients with asymptomatic carotid stenosis. In 17 out of 23 patients we found waveforms consistent with those predicted for a collateralized COW, with minimal differences in delay, velocity magnitude and resistivity index. In 6 cases, some unexpected findings were noted, such as large delays for 2 patients ≤ 50% stenosis, and a large velocity difference with low delay for 4 patients. More studies are needed to elucidate the role of incomplete intracranial collateralization on the hemodynamics around carotid plaque and to use imaging of the COW to corroborate our results.

  12. 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

  13. 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.

  14. 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

  15. Hemodynamic and Hematologic Effects of Histotripsy of Free-Flowing Blood: Implications for US-mediated Thrombolysis

    PubMed Central

    Devanagondi, Rajiv; Zhang, Xi; Xu, Zhen; Ives, Kimberly; Levin, Albert; Gurm, Hitinder; Owens, Gabe E.

    2015-01-01

    Purpose Histotripsy employs pulsed cavitational ultrasound for non-invasive tissue ablation. Some forms of therapeutic ultrasound cause intravascular hemolysis. We investigated the extent and consequences of histotripsy induced hemolysis in vivo. Materials and Methods Porcine femoral venous blood was treated with histotripsy in 11 animals with systemic heparinization and 11 without heparin. Serum and hemodynamic measurements were obtained at 0, 2, 5, 10, 15, 30 minutes, and 48–72 hours post-procedure. Fischer’s exact test was used to determine differences in mortality between heparinized and non-heparinized groups. A linear mixed effects model was used to test for differences in blood-analytes and hemodynamic variables over time. Results Of 11 non-heparin treated animals, 5 died during or immediately following histotripsy (non-heparin mortality 45% vs. heparin mortality 0%, p=0.035). Serum hematocrit, free hemoglobin, LDH, and right ventricular systolic pressure (RVSP) changed significantly (p<0.001) over the treatment time. Serum hematocrit decreased slightly (32.5 ± 3.6 to 29.4 ± 4.2%), while free hemoglobin (6.2 ± 4.6 to 348 ± 100 mg/dL), LDH (365 ± 67.8 ± to 722 ± 84.7 U/L), and RVSP (23.2 ± 7.2 to 39.7 ± 12.3 mmHg) increased. After 48 to 72 hours, hematocrit remained slightly decreased (p=0.005), while LDH and free hemoglobin remained slightly increased compared to baseline (both p<0.001). Conclusion Intravascular histotripsy applied to free flowing venous blood is safe with systemic heparinization, causing only transient hemodynamic and metabolic disturbances, thereby supporting its use as a future non-invasive thrombolytic therapy modality. PMID:25952642

  16. Relationship between angiotensin-(1-7) and angiotensin II correlates with hemodynamic changes in human liver cirrhosis

    PubMed Central

    Vilas-Boas, Walkíria Wingester; Ribeiro-Oliveira Jr, Antônio; Pereira, Regina Maria; da Cunha Ribeiro, Renata; Almeida, Jerusa; Nadu, Ana Paula; Simões e Silva, Ana Cristina; dos Santos, Robson Augusto Souza

    2009-01-01

    AIM: To measure circulating angiotensins at different stages of human cirrhosis and to further evaluate a possible relationship between renin angiotensin system (RAS) components and hemodynamic changes. METHODS: Patients were allocated into 4 groups: mild-to-moderate liver disease (MLD), advanced liver disease (ALD), patients undergoing liver transplantation, and healthy controls. Blood was collected to determine plasma renin activity (PRA), angiotensin (Ang) I, Ang II, and Ang-(1-7) levels using radioimmunoassays. During liver transplantation, hemodynamic parameters were determined and blood was simultaneously obtained from the portal vein and radial artery in order to measure RAS components. RESULTS: PRA and angiotensins were elevated in ALD when compared to MLD and controls (P < 0.05). In contrast, Ang II was significantly reduced in MLD. Ang-(1-7)/Ang II ratios were increased in MLD when compared to controls and ALD. During transplantation, Ang II levels were lower and Ang-(1-7)/Ang II ratios were higher in the splanchnic circulation than in the peripheral circulation (0.52 ± 0.08 vs 0.38 ± 0.04, P < 0.02), whereas the peripheral circulating Ang II/Ang I ratio was elevated in comparison to splanchnic levels (0.18 ± 0.02 vs 0.13 ± 0.02, P < 0.04). Ang-(1-7)/Ang II ratios positively correlated with cardiac output (r = 0.66) and negatively correlated with systemic vascular resistance (r = -0.70). CONCLUSION: Our findings suggest that the relationship between Ang-(1-7) and Ang II may play a role in the hemodynamic changes of human cirrhosis. PMID:19469002

  17. Cerebral Hemodynamics and Cognitive Function in Cirrhotic Patients with Hepatic Encephalopathy

    PubMed Central

    Zhou, Yuqing; Dong, Qian; Zhang, Rong; Zhou, Shunfeng; Li, Linqiang; Cheng, Keran; Kong, Rui; Yu, Qiang; Xu, Shizan; Li, Jingjing; Li, Sainan; Feng, Jiao; Wu, Liwei; Liu, Tong; Lu, Xiya; Xia, Yujing

    2016-01-01

    Aims. To investigate cerebral hemodynamics in cirrhotic patients with HE and to observe effects of treatment in cerebral hemodynamics and correlations among ammonia, cerebral hemodynamics, and cognitive function. Methods. There were four groups: healthy controls (group 1), cirrhosis without HE (group 2), cirrhosis with MHE (group 3), and cirrhosis with OHE (group 4). Ammonia and cerebral hemodynamics (by TCD) were assessed. Patients in group 3 were subsequently randomized to two subgroups: the control (group A) and the treated (group B, treated with lactulose for two months), and they were retested for ammonia and TCD after treatment. Results. Ammonia, Vm, Vd, PI, and RI were statistically different before treatment, and ammonia, PI, and RI levels paralleled the severity of HE (P < 0.05). In group B, Vd increased and ammonia, PI, and RI declined following treatment (P < 0.05), while there were no differences in group A (P > 0.05). Correlations were found between ammonia and Vd, PI, RI, NCT-A, and DST and also found between Vd, PI, RI, and NCT-A and DST (P < 0.05). Conclusions. This study revealed that cerebral hemodynamics were related to the severity of HE and cerebral autoregulation was impaired. There were tight correlations among ammonia, cerebral hemodynamics, and cognitive function, and, following treatment, cerebral hemodynamics improved. PMID:28096811

  18. Correlation between electrical and hemodynamic responses during visual stimulation with graded contrasts

    NASA Astrophysics Data System (ADS)

    Si, Juanning; Zhang, Xin; Li, Yuejun; Zhang, Yujin; Zuo, Nianming; Jiang, Tianzi

    2016-09-01

    Brain functional activity involves complex cellular, metabolic, and vascular chain reactions, making it difficult to comprehend. Electroencephalography (EEG) and functional near infrared spectroscopy (fNIRS) have been combined into a multimodal neuroimaging method that captures both electrophysiological and hemodynamic information to explore the spatiotemporal characteristics of brain activity. Because of the significance of visually evoked functional activity in clinical applications, numerous studies have explored the amplitude of the visual evoked potential (VEP) to clarify its relationship with the hemodynamic response. However, relatively few studies have investigated the influence of latency, which has been frequently used to diagnose visual diseases, on the hemodynamic response. Moreover, because the latency and the amplitude of VEPs have different roles in coding visual information, investigating the relationship between latency and the hemodynamic response should be helpful. In this study, checkerboard reversal tasks with graded contrasts were used to evoke visual functional activity. Both EEG and fNIRS were employed to investigate the relationship between neuronal electrophysiological activities and the hemodynamic responses. The VEP amplitudes were linearly correlated with the hemodynamic response, but the VEP latency showed a negative linear correlation with the hemodynamic response.

  19. Establishment of the intracranial hemodynamic model based on contrast medium and clinical applications

    PubMed Central

    Cheng, Yaoer; He, Wen

    2016-01-01

    Abstract Ischemic cerebrovascular diseases are one of the most common vascular diseases in aged people and CT perfusion (CTP) is a very popular tool to detect the ischemic changes in brain vascular. The present study aims to establish a novel intracranial hemodynamic model to simulate anterior cerebral artery blood flow, and compare the actual and simulated hemodynamic parameters of healthy people and patients with carotid stenosis or occlusion. A mathematical model of the intracranial hemodynamic was generated using MATLAB software, and data from patients with or without infarct disease (57 and 44 cases, respectively) were retrospectively collected to test the new model. The actual time-density curve (TDC) of anterior cerebral artery was obtained from the original intracranial CTP data, and simulated TDC was calculated from our intracranial hemodynamic model. All model parameters were adjusted according to patients’ sex, height, and weight. Time to peak enhancement (TTP), maximum enhancement (ME), and mean transit time (MTT) were selected to evaluate the status of hemodynamics. In healthy people, there were no significant differences of TTP and ME between actual and simulated curves. For patients with infarct symptoms, ME was significantly decreased in actual data compared with simulated curve, while there was no obvious difference of TTP between actual and simulated data. Moreover, MTT was delayed in infarct patients compared with healthy people. Our group generated a computer-based, physiologic model to simulate intracranial hemodynamics. The model successfully simulated anterior cerebral artery hemodynamics in normal healthy people and showed noncompliant ME and MTT in infarct patients, reflecting their abnormal cerebral hemodynamic status. The digital model is reliable and may help optimize the protocol of contrast medium enhancement in intracranial CT, and provide a solid tool to study intracranial hemodynamics. PMID:27930555

  20. Emerging Techniques for Evaluation of the Hemodynamics of Intracranial Vascular Pathology

    PubMed Central

    Huang, Melissa; Chien, Aichi

    2015-01-01

    Advances in imaging modalities have improved the assessment of intracranial hemodynamics using non-invasive techniques. This review examines new imaging modalities and clinical applications of currently available techniques, describes pathophysiology and future directions in hemodynamic analysis of intracranial stenoses, aneurysms and arteriovenous malformations and explores how hemodynamic analysis may have prognostic value in predicting clinical outcomes and assist in risk stratification. The advent of new technologies such as pseudo-continuous arterial spin labeling, accelerated magnetic resonance angiography (MRA) techniques, 4D digital subtraction angiography, and improvements in clinically available techniques such as phase-contrast MRA may change the landscape of vascular imaging and modify current clinical practice guidelines. PMID:25924168

  1. Diagnosis and treatment guidelines for aberrant portal hemodynamics: The Aberrant Portal Hemodynamics Study Group supported by the Ministry of Health, Labor and Welfare of Japan.

    PubMed

    2017-01-06

    Idiopathic portal hypertension (IPH), causing aberrant portal hemodynamics, is a disease with an as yet unidentified cause and no established treatment protocol. The Japanese research group on IPH in Japan was set up in 1975 by the Ministry of Health, Labor and Welfare. Extrahepatic portal obstruction and Budd-Chiari syndrome (BCS) have since been added to the group's research subjects. The aims of the research group are to accurately evaluate the current status of the three diseases in Japan, elucidate their etiology and pathogenesis, and develop new treatments. Due to the long-term efforts of the Japanese research group, aberrant portal hemodynamics has been investigated in a variety of aspects, from epidemiological and pathological studies to molecular biology analyses. As a result, it has been shown that there are abnormal genes in the liver, specific for IPH. In addition, pathological findings of BCS were internationally compared and the difference in findings between Japan and Europe (or North America) has been clarified. Furthermore, it was found that complication rates of hepatocellular carcinoma in BCS were higher in Japan. Based on the research, "Diagnosis and treatment of aberrant portal hemodynamics (2001)", including diagnostic criteria for aberrant portal hemodynamics, was published in 2001. In 2013, it was revised to "Diagnosis and treatment guidelines for aberrant portal hemodynamics (2013)" after the incorporation of diagnosis and treatment in accordance with its current status.

  2. Simultaneous EEG and diffuse optical imaging of seizure-related hemodynamic activity in the newborn infant brain

    NASA Astrophysics Data System (ADS)

    Hebden, Jeremy C.; Cooper, Robert J.; Gibson, Adam; Everdell, Nick; Austin, Topun

    2012-06-01

    An optical imaging system has been developed which uses measurements of diffusely reflected near-infrared light to produce maps of changes in blood flow and oxygenation occurring within the cerebral cortex. Optical sources and detectors are coupled to the head via an array of optical fibers, on a probe held in contact with the scalp, and data is collected at a rate of 10 Hz. A clinical electroencephalography (EEG) system has been integrated with the optical system to enable simultaneous observation of electrical and hemodynamic activity in the cortex of neurologically compromised newborn infants diagnosed with seizures. Studies have made a potentially critically important discovery of previously unknown transient hemodynamic events in infants treated with anticonvulsant medication. We observed repeated episodes of small increases in cortical oxyhemoglobin concentration followed by a profound decrease in 3 of 4 infants studied, each with cerebral injury who presented with neonatal seizures. This was not accompanied by clinical or EEG seizure activity and was not present in nineteen matched controls. The underlying cause of these changes is currently unknown. We tentatively suggest that our results may be associated with a phenomenon known as cortical spreading depolarization, not previously observed in the infant brain.

  3. 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; Gianesini, Sergio; 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

  4. Resting hemodynamics after total versus standard orthotopic heart transplantation.

    PubMed

    Aleksic, I; Czer, L S; Freimark, D; Takkenberg, J J; Dalichau, H; Valenza, M; Blanche, C; Queral, C A; Nessim, S; Trento, A

    1996-08-01

    Total orthotopic heart transplantation (TOHT) requires longer surgery than standard orthotopic heart transplantation (SOHT), but offers normal anatomy and synchronous atrial contraction. We endeavored to test whether TOHT improves resting hemodynamics. We analyzed 60 patients with SOHT and 66 with TOHT transplanted between 12/89 and 7/94. Age, preoperative NYHA class, ejection fraction, and donor characteristics were similar. After applying exclusion criteria at 2 weeks postoperatively, 53 SOHT and 58 TOHT patients were accepted for further study. Right-heart hemodynamics were examined at 2 weeks and 6 months posttransplant. Despite a longer ischemic time (161 +/- 36 vs. 142 +/- 37 min, p = 0.004), cardiac output and index were higher in the TOHT group at 2 weeks (6.1 +/- 1.4 vs. 5.4 +/- 1.0 L/min, TOHT vs. SOHT, p = 0.01; and 3.3 +/- 0.7 vs. 2.9 +/- 0.6 L/min/m2, p = 0.005) but similar at 6 months (5.9 +/- 1.2 vs. 5.6 +/- 1.4 L/min; and 3.0 +/- 0.6 vs. 2.9 +/- 0.7 L/min/m2). Right-atrial pressure was lower with TOHT at both time points (7 +/- 4 vs. 9 +/- 4 mmHg, p = 0.02: and 5 +/- 2 vs. 7 +/- 3, p = 0.0006). Wedge pressure was similar at 2 weeks (12 +/- 5 vs. 13 +/- 5, p = 0.045). Heart rate (bpm) was higher at both time points with TOHT (84 +/- 10 vs. 75 +/- 12, p = 0.0003: and 90 +/- 12 vs. 82 +/- 9, p = 0.0006). Pulmonary vascular resistance was similar at both time points. Despite a longer ischemic time, total orthotopic heart transplantation does not impair postoperative cardiac function. There is an early improvement in cardiac output, a sustained higher heart rate reflecting preservation of donor sinus node function, and a lower right-atrial pressure.

  5. Cardioselectivity, kinetics, hemodynamics, and metabolic effects of xamoterol.

    PubMed

    Jennings, G; Bobik, A; Oddie, C; Restall, R

    1984-05-01

    Xamoterol is a new orally active partial beta-adrenoceptor agonist. Its kinetics, hemodynamic and metabolic effects, and cardioselectivity were investigated in eight normal subjects. Plasma xamoterol concentrations after 100 micrograms/kg iv declined biexponentially over 8 hr and t 1/2 beta averaged 2.6 hr. Resting heart rate (HR) increased slightly in the supine position but was unchanged on sitting. Systolic blood pressure (SBP) rose by 5 to 10 mm Hg and cardiac index (CI) rose 15% to 20%. Both parameters were above control values 6 hr after dosing, when plasma xamoterol concentrations had fallen to about 10 ng/ml. There were no changes in diastolic or mean arterial pressure (MAP). During graded exercise the effects of xamoterol on HR and SBP were the reverse of those at rest, with lowering of exercise HR and SBP at higher work loads. CI during exercise was not altered by xamoterol. Doses of xamoterol were calculated from the kinetic data to give plasma concentrations of 100, 200, 400, and 800 ng/ml. HR and blood pressure effects at each xamoterol level were compared before and after inhibition of cardiovascular reflexes with prazosin, atropine, and clonidine. Hemodynamic effects of xamoterol and isoproterenol were compared. Before autonomic block xamoterol increased HR by 10 bpm and MAP by 7 mm Hg at the highest dose. After autonomic block there was a 200% to 300% rise in HR at each dose and MAP still rose. The rise in MAP after block could be entirely accounted for by a 23% increase in CI because total peripheral resistance did not change. The effects of isoproterenol after autonomic block were a rise in HR and a fall in MAP. Metabolic responses to xamoterol were measured at the four dose levels. There was a dose-related increase in nonesterified fatty acids and a fall in plasma lactate levels but no changes in plasma renin activity or blood glucose. Results suggest that xamoterol is a cardioselective partial beta-adrenoceptor agonist in man.

  6. C5a-induced hemodynamic and hematologic changes in the rabbit. Role of cyclooxygenase products and polymorphonuclear leukocytes.

    PubMed Central

    Lundberg, C.; Marceau, F.; Hugli, T. E.

    1987-01-01

    Hemodynamic and hematologic changes occurring after intravascular complement activation have implicated the anaphylatoxins in this response. In this study, the hemodynamic and hematologic effects of purified C5a were investigated in rabbits; and involvement of prostanoids, histamine, and polymorphonuclear leukocytes (PMNs) were examined. The anaphylatoxin C5a induces a reversible systemic arterial hypotension which coincides with an increase in central venous pressure (CVP), decreased cardiac output (CO), increased plasma prostanoid levels, as well as neutropenia. Total peripheral resistance (TPR) remained unchanged. The cyclooxygenase inhibitor indomethacin abolished the C5a-induced hypotension and normalized plasma prostanoid levels without altering the C5a-induced neutropenia. The thromboxane (Tx) A2 synthetase inhibitor dazoxiben reduced TxB2 plasma levels and increased 6-keto-prostaglandin PGF1 alpha and PGE2 levels without altering the hypotensive response. However, with dazoxiben treatment both TPR and CVP decreased. The H2-receptor antagonist cimetidine reduced C5a-induced hypotension and diminished prostanoid release. Both the hypotensive response and elevated prostanoid release were observed after C5a challenge in animals rendered neutropenic prior to challenge. It is concluded that C5a-induced arterial hypotension in the rabbit is a PMN-independent reaction, mediated through cyclooxygenase products and, to some degree, by histamine. The mechanism producing systemic arterial hypotension does not seem to involve peripheral vasodilation but appears to be a secondary effect of pulmonary vasoconstriction, possibly mediated by TxA2. PMID:3115110

  7. In Vitro Hemodynamic Evaluation of Five 6 Fr and 8 Fr Arterial Cannulae in Simulated Neonatal Cardiopulmonary Bypass Circuits.

    PubMed

    Wang, Shigang; Palanzo, David; Kunselman, Allen R; Ündar, Akif

    2016-01-01

    The objective of this study was to evaluate five small-bore arterial cannulae (6Fr and 8Fr) in terms of pressure drop and hemodynamic performance in simulated neonatal cardiopulmonary bypass (CPB) circuits. The experimental circuits consisted of a Jostra HL-20 roller pump, a Terumo Capiox Baby FX05 oxygenator with integrated arterial filter, an arterial and a venous tubing (1/4, 3/16, or 1/8 in × 150 cm), and an arterial cannula (Medtronic Bio-Medicus 6Fr and 8Fr, Maquet 6Fr and 8Fr, or RMI Edwards 8Fr). The circuit was primed using lactated Ringer's solution and heparinized packed human red blood cells (hematocrit 30%). Trials were conducted at different flow rates (6Fr: 200-400 mL/min; 8Fr: 200-600 mL/min) and temperatures (35 and 28°C). Flow and pressure data were collected using a custom-based data acquisition system. Higher circuit pressure, circuit pressure drop, and hemodynamic energy loss across the circuit were recorded when using small-bore arterial cannula and small inner diameter arterial tubing in a neonatal CPB circuit. The maximum preoxygenator pressures reached 449.7 ± 1.0 mm Hg (Maquet 6Fr at 400 mL/min), and 395.7 ± 0.4 mm Hg (DLP 8Fr at 600 mL/min) when using 1/8 in ID arterial tubing at 28°C. Hypothermia further increased circuit pressure drop and hemodynamic energy loss. Compared with the others, the RMI 8Fr arterial cannula had significantly lower pressure drop and energy loss. Maquet 6Fr arterial cannula had a greater pressure drop than the DLP 6Fr. A small-bore arterial cannula and arterial tubing created high circuit pressure drop and hemodynamic energy loss. Appropriate arterial cannula and arterial tubing should be considered to match the expected flow rate. Larger cannula and tubing are recommended for neonatal CPB. Low-resistance neonatal arterial cannulae need to be developed.

  8. Variability of hemodynamic responses to acute digitalization in chronic cardiac failure due to cardiomyopathy and coronary artery disease.

    PubMed

    Cohn, K; Selzer, A; Kersh, E S; Karpman, L S; Goldschlager, N

    1975-04-01

    Eight patients with chronic congestive heart failure (four with cardiomyopathy and four with ischemic heart disease) underwent hemodynamic studies during acute administration of digoxin, given intravenously in two 0-5 mg doses 2 hours apart. Observations were made before administration of digitalis (control period) and serially therafter for 4 hours after the first dose. Resting mean cardiac index and pulmonary arterial wedge pressure were as follows: 2.0 liters/min per m2 and 23 mm Hg (control period); 2.1 and 24 (at 1 hour); 2.0 and 23 (at 2 hours); 2.7 and 19 (at 3 hours); and 2.3 and 20 (at 4 hours). Exercise responses of mean cardiac index and pulmonary arterial wedge pressure in five patients were: 3.1 liters/min per m2 and 36 mm Hg (control period); 3.2 and 33 (at 1 hour); 3.2 and 28 (at 2 hours); 3.1 and 27 (at.3 hours); and 3.4 and 31 (at 4 hours). The pulmonary arterial wedge pressure remained elevated during exercise in all cases. Arrhythmias were seen in five patients after administration of 0.5 mg of digoxin. Hemodynamic improvement at 4 hours involving both reduced filling pressure and increased blood flow was observed in only two patients at rest and in one additional patient during exercise. Acute deterioration of cardiac function (elevated pulmonary arterial wedge pressure of decreased cardiac index) occurred 30 minutes after administration of digoxin in four patients, concomitantly with increased systemic resistance. In six patients, a peak hemodynamic effect appeared 1 to 1 1/2 hours after administration of digoxin, with partial or total loss of initial benefit by 2 and 4 hours. In previously performed studies observations have seldom exceeded 1 hour; the results of this 4 hour study suggest that, in patients with cardiomyopathy or coronary artery disease and chronic congestive heart failure, acute digitalization does not necessarily lead to consistent, marked or lasting hemodynamic improvement. Thus, current concepts of the use of digitalis is

  9. Temporal analysis of fluctuations in cerebral hemodynamics revealed by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Toronov, Vlad; Fantini, Sergio; Franceschini, Maria-Angela; Filiaci, Mattia A.; Wolf, Martin; Gratton, Enrico

    2000-04-01

    We have non-invasively studied the motor cortex hemodynamics in human subjects under rest and motor stimulation conditions using a multichannel near-IR tissue spectrometer. We obtained optical maps of oxy- and deoxy-hemoglobin concentration changes in terms of amplitudes of folding average, power spectrum and coherence at the stimulation repetition frequency, and the phase synchronization index. Under periodic motor stimulation conditions, we observed coherence and phase synchronization of the local hemodynamic changes with stimulation.

  10. Comparing a non-invasive hemodynamic monitor with minimally invasive monitoring during major open abdominal surgery

    PubMed Central

    Ong, Lawrence; Liu, Hong

    2014-01-01

    Abstract As part of the enhanced recovery after surgery (ERAS) protocol, the goal-directed fluid management with hemodynamic monitoring can effectively guide perioperative fluid use and significantly improve the outcomes in high-risk patients undergoing major surgeries. Several minimally invasive and non-invasive monitoring devices are commercially available for clinical use. As part of an internal evaluation, we reported the results from three different hemodynamic monitoring devices used in a patient undergoing a major abdominal surgery. PMID:25050116

  11. [Cerebral hemodynamics in patients with neurosensory hearing loss before and after magnetotherapy].

    PubMed

    Morenko, V M; Enin, I P

    2001-01-01

    Magnetotherapy effects on cerebral hemodynamics were studied using rheoencephalography (REG). When the treatment results and changes in cerebral hemodynamics were compared it was evident that normalization or improvement of vascular status in vertebrobasilar and carotid territories registered at REG results in better hearing. This confirms the role of vascular factor in pathogenesis of neurosensory hypoacusis of different etiology and effectiveness of magnetotherapy in such patients.

  12. Definition of hypotension and assessment of hemodynamics in the preterm neonate.

    PubMed

    Cayabyab, R; McLean, C W; Seri, I

    2009-05-01

    The complexity of postnatal cardiovascular transition has only recently been better appreciated in the very low birth weight neonate. As blood pressure in itself poorly represents systemic blood flow, especially when the fetal channels are open and the developmentally regulated vital organ assignment may not have been completed, efforts to measure systemic blood flow have resulted in a novel, yet incomplete, understanding of the principles and clinical relevance of cardiovascular adaptation during postnatal transition in this patient population. This article describes the definition of hypotension based on the principles of cardiovascular physiology, and reviews the tools available to the clinician and researcher at the bedside to examine the complex relationship among blood pressure, systemic and organ blood flow, and tissue oxygen delivery and oxygen demand in vital and non-vital organs in the very low birth weight neonate. Only after gaining an insight into these complex relationships and processes will we be able to design clinical trials of selected treatment modalities targeting relevant patient sub-populations for the management of neonatal cardiovascular compromise. Only clinical trials based on a solid understanding of developmental cardiovascular physiology tailored to the appropriate patient sub-population hold the promise of being effective and practical, and can lead to improvements in both hemodynamic parameters and clinically relevant outcome measures.

  13. 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.

  14. The Effect of Hemodynamic Remodeling on the Survival of Arterialized Venous Flaps

    PubMed Central

    Yan, Hede; Kolkin, Jon; Zhao, Bin; Li, Zhefeng; Jiang, Shichao; Wang, Wei; Xia, Zhen; Fan, Cunyi

    2013-01-01

    Objective To evaluate the effect of hemodynamic remodeling on the survival status of the arterialized venous flaps (AVFs) and investigate the mechanism of this procedure. Materials and Methods Two 7 x 9 cm skin flaps in each rabbit (n=36) were designed symmetrically in the abdomen. The thoracoepigastric pedicle and one femoral artery were used as vascular sources. Four groups were included: Composite skin grafts group and arterial perfusion group were designed in one rabbit; AVF group and hemodynamic remodeling group by ligation of the thoracoepigastric vein in the middle were outlined in another rabbit. Flap viability, status of vascular perfusion and microvasculature, levels of epidermal metabolite and water content in each group were assessed. Results Highly congested veins and simple trunk veins were found using angiography in the AVF group; while a fairly uniform staining and plenty of small vessels were observed in the hemodynamic remodeling group. The metabolite levels of the remodeling group are comparable with those in the arterial perfusion group. There was no statistically significant difference in the percentage of flap survival between the arterial perfusion group and hemodynamic remodeling group; however, significant difference was seen between the AVF group and the hemodynamic remodeling group. Conclusions Under the integrated perfusion mode, the AVFs are in an over-perfusion and non-physiological hemodynamic state, resulting in unreliability and unpredictability in flap survival; under the separated perfusion mode produced by remodeling, a physiological-like circulation will be created and therefore, better flap survival can be expected. PMID:24265782

  15. Hemodynamics before and after bleb formation in cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Cebral, Juan R.; Radaelli, Alessandro; Frangi, Alejandro; Putman, Christopher M.

    2007-03-01

    We investigate whether blebs in cerebral aneurysms form in regions of low or high wall shear stress (WSS), and how the intraaneurysmal hemodynamic pattern changes after bleb formation. Seven intracranial aneurysms harboring well defined blebs were selected from our database and subject-specific computational models were constructed from 3D rotational angiography. For each patient, a second anatomical model representing the aneurysm before bleb formation was constructed by smoothing out the bleb. Computational fluid dynamics simulations were performed under pulsatile flow conditions for both models of each aneurysm. In six of the seven aneurysms, the blebs formed in a region of elevated WSS associated to the inflow jet impaction zone. In one, the bleb formed in a region of low WSS associated to the outflow zone. In this case, the inflow jet maintained a fairly concentrated structure all the way to the outflow zone, while in the other six aneurysms it dispersed after impacting the aneurysm wall. In all aneurysms, once the blebs formed, new flow recirculation regions were formed inside the blebs and the blebs progressed to a state of low WSS. Assuming that blebs form due to a focally damaged arterial wall, these results seem to indicate that the localized injury of the vessel wall may be caused by elevated WSS associated with the inflow jet. However, the final shape of the aneurysm is probably also influenced by the peri-aneurysmal environment that can provide extra structural support via contact with structures such as bone or dura matter.

  16. Clinical and hemodynamic effects of the new dilator drug molsidomine.

    PubMed

    Malcolm, A D

    1985-03-01

    The effects of a single 2 mg oral dose of molsidomine were assessed with treadmill multistage exercise testing in six men with stable angina. A double-blind, placebo-controlled protocol was used, with exercise to the point when anginal pain forced the patient to stop. Exercise was undertaken before and at 1/2, 1 1/2, 4, and 6 hours after drug administration. Molsidomine improved exercise performance, with the best antianginal effect at 1 1/2 hours after administration, when the mean times to limiting angina were approximately 6 3/4 minutes with placebo and 11 1/2 minutes with molsidomine (p less than 0.05). The corresponding energy expenditures were 33.8 and 77.6 mets, an increase of 130% with the active drug. Intra-arterial blood pressure recording verified that molsidomine had a vasodilator hemodynamic profile, and the immediate postexercise rate-pressure product 1 1/2 hours after molsidomine treatment was 232 mm Hg/min X 10(-2), compared with 183 mm Hg/min X 10(-2) after administration of placebo (NS). Side effects of molsidomine were limited to headache in two patients.

  17. [Hemodynamic sequelae following valve replacement in patients with aortic regurgitation].

    PubMed

    Onishi, S; Handa, S; Ikeda, F; Hosokawa, M; Yoshino, H; Ogawa, S; Nakamura, Y; Soma, Y; Inoue, T

    1989-06-01

    Serial echocardiographic analyses of the left ventricle (LV) were performed in 61 patients with aortic regurgitation before, one-six months, and six years after aortic valve replacement (AVR). There was no significant difference in the preoperative hemodynamic and echocardiographic data between 54 survivors and six deceased patients. There was a linear correlation (r = 0.69) between LV end-diastolic volume (EDV) by cineangiography and LV end-diastolic dimension (LVDd) by echocardiography. In patients with LV end-diastolic pressure (EDP) less than 12 mmHg, the LV was markedly dilated before surgery, and LVDd was not normalized until half a year after surgery in half the cases. In 20 patients with LVEDP greater than 12 mmHg, LVDd was normalized in 17 patients up to half a year after surgery. In 11 patients with LV end-systolic dimension (LVDs) greater than 5.2 cm, LVDs was not normalized until six years post surgery in three patients. LVDd was improved six years after surgery in patients with LVDs less than 5.2 cm. Echocardiographically-determined LVDs less than 5.2 cm is recommended for preservation of LV function following aortic valve replacement.

  18. 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.

  19. Posttraumatic shock in children: CT findings associated with hemodynamic instability.

    PubMed

    Sivit, C J; Taylor, G A; Bulas, D I; Kushner, D C; Potter, B M; Eichelberger, M R

    1992-03-01

    Twenty-seven of 1,018 children evaluated with contrast material-enhanced computed tomography (CT) after blunt trauma demonstrated a characteristic hypoperfusion complex. This complex was usually seen in young children (median age, 2 years). CT findings in all 27 patients included a dilated, fluid-filled bowel and abnormally intense enhancement of the bowel wall, mesentery, kidneys, aorta, and inferior vena cava. Twenty-four percent of all children with a Trauma Score of 10 or less and 20% with a Glasgow Coma Score of 6 or less had the hypoperfusion complex. All 27 patients had a normal blood pressure immediately before CT, but five (19%) became hypotensive within 10 minutes of intravenous contrast material administration. Twenty-three children (85%) died. Of 16 children who survived 24 hours, four (25%) developed renal insufficiency. The intense multiorgan enhancement pattern seen in the hypoperfusion complex indicates tenuous hemodynamic stability. Recognition that the constellation of CT findings is due to hypovolemic shock and not to injured viscera helps avoid unnecessary laparotomy.

  20. Renal Function and Hemodynamic Study in Obese Zucker Rats

    PubMed Central

    Park, Sung Kwang; Kang, Sung Kyew

    1995-01-01

    Objectives To investigate the renal function and hemodynamic changes in obesity and hyperinsulinemia which are characteristics of type II diabetes. Methods Studies were carried out in two groups of female Zucker rats. Group 1 rats were obese Zucker rats with hereditary insulin resistance. Group 2 rats were lean Zucker rats and served as controls. In comparison with lean Zucker rats, obese Zucker rats exhibited hyperinsulinemia but normoglycemia. Micropuncture studies and morphologic studies were performed in these rats. Results Functional studies showed that obese Zucker rats exhibited increases in kidney weight and GFR(obese Zucker, 1.23±.07)ml/min; lean Zucker, 0.93±.03ml/min). Micropuncture studies revealed that the increase in GFR in obese Zucker rats was attributable to the increases in the single nephron plasma flow rate and glomerular transcapillary hydraulic pressure. The glomerular ultrafiltration coefficient was the same in both groups. Morphologic studies revealed that the increase in GFR in obese Zucker rats was associated with an increase in glomerular volume. Conclusions These results suggest that obesity and hyperinsulinemia, which are the characteristics of type II diabetes, can be associated with glomerular hyperfiltration and glomerular capillary hypertension. PMID:7626557

  1. 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.

  2. Approximating hemodynamics of cerebral aneurysms with steady flow simulations.

    PubMed

    Geers, A J; Larrabide, I; Morales, H G; Frangi, A F

    2014-01-03

    Computational fluid dynamics (CFD) simulations can be employed to gain a better understanding of hemodynamics in cerebral aneurysms and improve diagnosis and treatment. However, introduction of CFD techniques into clinical practice would require faster simulation times. The aim of this study was to evaluate the use of computationally inexpensive steady flow simulations to approximate the aneurysm's wall shear stress (WSS) field. Two experiments were conducted. Experiment 1 compared for two cases the time-averaged (TA), peak systole (PS) and end diastole (ED) WSS field between steady and pulsatile flow simulations. The flow rate waveform imposed at the inlet was varied to account for variations in heart rate, pulsatility index, and TA flow rate. Consistently across all flow rate waveforms, steady flow simulations accurately approximated the TA, but not the PS and ED, WSS field. Following up on experiment 1, experiment 2 tested the result for the TA WSS field in a larger population of 20 cases covering a wide range of aneurysm volumes and shapes. Steady flow simulations approximated the space-averaged WSS with a mean error of 4.3%. WSS fields were locally compared by calculating the absolute error per node of the surface mesh. The coefficient of variation of the root-mean-square error over these nodes was on average 7.1%. In conclusion, steady flow simulations can accurately approximate the TA WSS field of an aneurysm. The fast computation time of 6 min per simulation (on 64 processors) could help facilitate the introduction of CFD into clinical practice.

  3. Hemodynamics and transient flow reversal in real deployed stents

    NASA Astrophysics Data System (ADS)

    Metcalfe, Ralph; Ionescu, Mircea

    2011-11-01

    Restenosis rates caused by neointimal hyperplasia are relatively high (~ 30 %) after stent implantation in stenosed arteries. The flow around stent struts under steady and unsteady conditions using computational hemodynamics (CHD) was studied to identify contributing factors to the formation of low and oscillating wall shear stress regions that have been shown to promote endothelial dysfunction and atherosclerotic plaque formation in arteries. Datasets of the Neuroform, BxVelocity, and Taxus stents deployed in straight polymer tubes were obtained from high resolution micro computed tomography. Finite volume CHD simulations of steady and unsteady flow with and without flow reversal were performed. Stagnation zones were noticed adjacent to the strut junctions as the flow enters and exits the stent cells. The stagnation zones were larger in the case of the stents with larger strut diameter (BxVelocity, Taxus), wider strut junctions and larger angles between the struts. Unsteady flow simulations showed enhanced flow reversal with thicker struts and large regions of recirculation flow developing inside the stent at Reynolds numbers higher than 200. It was shown that alterations in blood flow due to real stent deployment (strut prolapse, junction misalignment) cannot be captured with computer generated stent models, that stent specific geometry, and time dependent flow effects can locally alter the wall shear stress and stagnation zones.

  4. Hemodynamic analysis and design of a paracorporeal artificial lung device.

    PubMed

    Ha, Roy R; Wang, Dongfang; Zwischenberger, Joseph B; Clark, John W

    2006-03-01

    We have extended our model of the ovine pulmonary circulation to include a model of a paracorporeal artificial lung (AL) and its attachments to the natural pulmonary circulation in two configurations: in series and in parallel. Our model of the natural lung (NL) circulation is first shown to be in agreement with hemodynamic and input impedance data from the open literature. We then study design efficacy of the AL in terms of its housing and attachments. A sensitivity analysis of the modified pulmonary circulation model reveals that there are three key parameters: inlet graft length (IGL) and the compliances of the inlet compliance chamber (CC) and housing of the artificial lung. Based on literature reports, we assume the right ventricle is well-matched to the impedance of the natural pulmonary circulation and adjust the parameters of the modeled AL circuit to achieve the best least-squares fit to natural pulmonary input impedance data. Best-fit parameters produce impedance curves that fit natural impedance well, particularly below 3 Hz, where both compliance and graft length have their largest effects. Of these parameters, the impedance profile is most sensitive to IGL. However, the compliances are important, as well, particularly at low frequencies.

  5. 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.

  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. Hemodynamic Modeling of Surgically Repaired Coarctation of the Aorta.

    PubMed

    Olivieri, Laura J; de Zélicourt, Diane A; Haggerty, Christopher M; Ratnayaka, Kanishka; Cross, Russell R; Yoganathan, Ajit P

    2011-12-01

    PURPOSE: Late morbidity of surgically repaired coarctation of the aorta includes early cardiovascular and cerebrovascular disease, shortened life expectancy, abnormal vasomodulator response, hypertension and exercise-induced hypertension in the absence of recurrent coarctation. Observational studies have linked patterns of arch remodeling (Gothic, Crenel, and Romanesque) to late morbidity, with Gothic arches having the highest incidence. We evaluated flow in native and surgically repaired aortic arches to correlate respective hemodynamic indices with incidence of late morbidity. METHODS: Three dimensional reconstructions of each remodeled arch were created from an anatomic stack of magnetic resonance (MR) images. A structured mesh core with a boundary layer was generated. Computational fluid dynamic (CFD) analysis was performed assuming peak flow conditions with a uniform velocity profile and unsteady turbulent flow. Wall shear stress (WSS), pressure and velocity data were extracted. RESULTS: The region of maximum WSS was located in the mid-transverse arch for the Crenel, Romanesque and Native arches. Peak WSS was located in the isthmus of the Gothic model. Variations in descending aorta flow patterns were also observed among the models. CONCLUSION: The location of peak WSS is a primary difference among the models tested, and may have clinical relevance. Specifically, the Gothic arch had a unique location of peak WSS with flow disorganization in the descending aorta. Our results suggest that varied patterns and locations of WSS resulting from abnormal arch remodeling may exhibit a primary effect on clinical vascular dysfunction.

  8. Effect of uninostril yoga breathing on brain hemodynamics: A functional near-infrared spectroscopy study

    PubMed Central

    Singh, Karamjit; Bhargav, Hemant; Srinivasan, TM

    2016-01-01

    Objectives: To measure the effect of the right and left nostril yoga breathing on frontal hemodynamic responses in 32 right handed healthy male subjects within the age range of 18–35 years (23.75 ± 4.14 years). Materials and Methods: Each subject practiced right nostril yoga breathing (RNYB), left nostril yoga breathing (LNYB) or breath awareness (BA) (as control) for 10 min at the same time of the day for three consecutive days, respectively. The sequence of intervention was assigned randomly. The frontal hemodynamic response in terms of changes in the oxygenated hemoglobin (oxyHb), deoxygenated hemoglobin (deoxyHb), and total hemoglobin (totalHb or blood volume) concentration was tapped for 5 min before (pre) and 10 min during the breathing practices using a 16 channel functional near-infrared system (FNIR100-ACK-W, BIOPAC Systems, Inc., U.S.A.). Average of the eight channels on each side (right and left frontals) was obtained for the two sessions (pre and during). Data was analyzed using SPSS version 10.0 through paired and independent samples t-test. Results: Within group comparison showed that during RNYB, oxyHb levels increased significantly in the left prefrontal cortex (PFC) as compared to the baseline (P = 0.026). LNYB showed a trend towards significance for reduction in oxyHb in the right hemisphere (P = 0.057). Whereas BA caused significant reduction in deoxyHb (P = 0.023) in the left hemisphere. Between groups comparison revealed that oxyHb and blood volume in the left PFC increased significantly during RNYB as compared to BA (oxyHb: P =0.012; TotalHb: P =0.017) and LNYB (oxyHb: P =0.024; totalHb: P =0.034). Conclusion: RNYB increased oxygenation and blood volume in the left PFC as compared to BA and LNYB. This supports the relationship between nasal cycle and ultradian rhythm of cerebral dominance and suggests a possible application of uninostril yoga breathing in the management of psychopathological states which show lateralized cerebral

  9. An impedance device for study of multisegment hemodynamic changes during orthostatic stress

    NASA Astrophysics Data System (ADS)

    Montgomery, L. D.; Hanish, H. M.; Marker, R. A.

    1989-11-01

    Definition of multisegment hemodynamic changes that take place in the body would provide a more complete understanding of the physiologic responses to various orthostatic stress techniques. A self-contained impedance device is described which may be used to measure the electrical transmission characteristics produced by blood flow and volume changes in six segments of the human body during head-up tilt, bed rest, and lower body negative pressure. The device consists of a module that contains the electronics for the impedance system, a separate controller/multiplexer, a personal computer interface/analog to digital conversion/power supply system, and the associated computer control softwave. The instrument is linear over a range of 0 to 200 ohms; provides analog outputs of base impedance, phase angle, pulsatile impedance change, and the first derivative of the pulsatile impedance changes; and can be used to automatically record basal impedance values into spread-sheet format with cycle times between 12 s and 1 h. Typical results are presented to illustrate its application in aerospace research.

  10. Hemodynamic monitoring of large animal chronic studies after median sternotomy: experiences with different telemetric physiological devices.

    PubMed

    Fujii, Yasuhiro; Pitsillides, Koullis; Ferro, Giuseppe; Kagawa, Hiroshi; Centola, Luca; Kinouchi, Katsushi; Zhu, Liqun; Ferrier, William T; Talken, Linda; Nasirov, Teimour; Riemer, R Kirk; Reinhartz, Olaf

    2015-01-01

    Telemetric physiological monitoring systems (TPMS) have enabled accurate continuous measurement of animal blood pressures and flows. However, few studies describe approaches for use of TPMS in the great vessels or inside the heart. We describe our initial experiences using two types of TPMSs. Twelve lambs (20-37 kg) underwent sternotomy. Two lambs were not instrumented and were killed at 14 days to confirm normal sternal wound healing (sham group, n = 2). Ten lambs underwent placement of either standard indwelling pressure-monitoring catheter and perivascular-flow-probe (CFP group, n = 3) or TPMS implantation (TPMS group, n = 7). The TPMS used were EG1-V3S2T-M2 (EG1, n = 5; Transonic Endogear Inc.) and Physio Tel Digital L21 (PTD, n = 2; Data Sciences Inc.). Two deaths because of respiratory problems occurred in TPMS group, attributed to lung compression by the implanted device. In TPMS group, more consistent trends of blood pressures and flows were recorded, and management of animals was easier and less labor-intensive. Comparing the two TPMSs, the initiation and renewal costs for each case was $28 K vs. $20 K and $1,700 vs. $0, (PTD versus EG1, respectively). In conclusion, TPMS implantation was feasible via median sternotomy in lambs. Telemetric physiological monitoring systems significantly improve reliability of hemodynamic monitoring in chronic survival animal study. EG1 was less costly than PTD.

  11. Mephedrone, a new designer drug of abuse, produces acute hemodynamic effects in the rat.

    PubMed

    Meng, Harry; Cao, James; Kang, Jiesheng; Ying, Xiaoyou; Ji, Junzhi; Reynolds, William; Rampe, David

    2012-01-05

    Mephedrone (4-methylmethcathinone) is a new and popular drug of abuse widely available on the Internet and still legal in some parts of the world. Clinical reports are now emerging suggesting that the drug displays sympathomimetic toxicity on the cardiovascular system but no studies have yet explored its cardiovascular effects. Therefore we examined the effects of mephedrone on the cardiovascular system using a combination of in vitro electrophysiology and in vivo hemodynamic and echocardiographic measurements. Patch clamp studies revealed that mephedrone, up to 30 μM, had little effect on the major voltage-dependent ion channels of the heart or on action potentials recorded in guinea pig myocytes. Subcutaneous administration of mephedrone (3 and 15 mg/kg) to conscious telemetry-implanted rats produced dose-dependent increases in heart rate and blood pressure which persisted after pre-treatment with reserpine. Echocardiographic analysis demonstrated that intravenous injection of mephedrone (0.3 and 1mg/kg) increased cardiac function, including cardiac output, ejection fraction, and stroke volume, similar to methamphetamine (0.3mg/kg). We conclude that mephedrone is not directly pro-arrhythmic, but induces substantial increases in heart rate, blood pressure and cardiac contractility and this activity contributes to the cardiovascular toxicity in people who abuse the drug.

  12. A 1D pulse wave propagation model of the hemodynamics of calf muscle pump function

    PubMed Central

    Keijsers, J M T; Leguy, C A D; Huberts, W; Narracott, A J; Rittweger, J; van de Vosse, F N

    2015-01-01

    The calf muscle pump is a mechanism which increases venous return and thereby compensates for the fluid shift towards the lower body during standing. During a muscle contraction, the embedded deep veins collapse and venous return increases. In the subsequent relaxation phase, muscle perfusion increases due to increased perfusion pressure, as the proximal venous valves temporarily reduce the distal venous pressure (shielding). The superficial and deep veins are connected via perforators, which contain valves allowing flow in the superficial-to-deep direction. The aim of this study is to investigate and quantify the physiological mechanisms of the calf muscle pump, including the effect of venous valves, hydrostatic pressure, and the superficial venous system. Using a one-dimensional pulse wave propagation model, a muscle contraction is simulated by increasing the extravascular pressure in the deep venous segments. The hemodynamics are studied in three different configurations: a single artery–vein configuration with and without valves and a more detailed configuration including a superficial vein. Proximal venous valves increase effective venous return by 53% by preventing reflux. Furthermore, the proximal valves shielding function increases perfusion following contraction. Finally, the superficial system aids in maintaining the perfusion during the contraction phase and reduces the refilling time by 37%. © 2015 The Authors. International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd. PMID:25766693

  13. [Functional state of the liver at modeling hemodynamic effects of the weightlessness in human organism].

    PubMed

    Afonin, B V; Ermolenko, A E; Inozemtsev, S L

    2012-01-01

    The radioisotope researches (RR) ofcholeresis function of a liver, the ultrasonic researches (USR) of a liver, the contractile gallbladder function (GF) and the gastroduodenoscopy (GDS) were carried out at 8 men after 24 hour duration of stay in antiorthostatic position--12 degrees (AOP), simulating arising in weightlessness of hemodynamics changes in abdominal cavity. The dynamic difficulty of venous blood outflow from a liver at simulated in antiorthostatic position changes of activation choleresis on an empty stomach was produced, by increase of a zone central perfusion of a liver parenchyma, biliary ductules dilation and of a gallbladder reduction, and were accompanied by choleresis in duodenum. The activation choleresis in a liver was accompanied by of reduction of the area of radioactive marker distribution in a liver, the decrease of hepatocytes metabolic activity and concentration function ofbiliary excretion system. Specificity of a functional condition of a liver within AOP reflects reaction caused by plethoric changes induced by body position, which is negative to vector of gravity. The mechanism of the revealed changes includes occurrence dynamic venous plethora in a liver, centralization hepatic blood flow with activation choleresis activity against the background tissual blood flow depletion in peripheral zones, reduction of hepatocytes metabolic activity and concentration function biliary excretion system.

  14. 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.

  15. Detrend-free hemodynamic data assimilation of two-stage Kalman estimator.

    PubMed

    Zhenghui, Hu; Pengcheng, Shi

    2011-01-01

    Spurious temporal drift is abundant in fMRI data, and its removal is a critical preprocessing step in fMRI data assimilation due to the sparse nature and the complexity of the data. Conventional data-driven approaches rest upon specific assumptions of the drift structure and signal statistics, and may lead to inaccurate results. In this paper we present an approach to the assimilation of nonlinear hemodynamic system, with special attention on drift. 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 two-stage unscented Kalman filter (UKF) to efficiently handle this problem. In this framework the assimilation can implement with original fMRI data without detrending preprocessing. The fMRI responses and drift were estimated simultaneously in an assimilation cycle. The efficacy of this approach is demonstrated in synthetic and real fMRI experiments. Results show that the joint estimation strategy produces more accurate estimation of physiological states, fMRI response and drift than separate processing due to no assumption of structure of the drift that is not available in fMRI data.

  16. Hemodynamic and metabolic basis of impaired exercise tolerance in patients with severe left ventricular dysfunction

    SciTech Connect

    Roubin, G.S.; Anderson, S.D.; Shen, W.F.; Choong, C.Y.; Alwyn, M.; Hillery, S.; Harris, P.J.; Kelly, D.T. )

    1990-04-01

    Hemodynamic and metabolic changes were measured at rest and during exercise in 23 patients with chronic heart failure and in 6 control subjects. Exercise was limited by leg fatigue in both groups and capacity was 40% lower in the patients with failure. At rest, comparing patients with control subjects, heart rate and right atrial and pulmonary wedge pressure were higher; cardiac output, stroke volume and work indexes and ejection fraction were lower; mean arterial and right atrial pressure and systemic resistance were similar. During all phases of exercise in patients with heart failure, pulmonary wedge pressure and systemic vascular resistance were higher and pulmonary vascular resistance remained markedly elevated compared with values in control subjects. Cardiac output was lower in the patients with failure, but appeared to have the same physiologic distribution in both groups during exercise. Although arterial-femoral venous oxygen content difference was higher in patients with heart failure, this increase did not compensate for the reduced blood flow. Even though the maximal oxygen consumption was significantly reduced, femoral venous lactate and pH values were higher than values in control subjects, but femoral venous pH was similar in both groups at their respective levels of maximal exercise. Ejection fraction was lower in those with heart failure at rest and did not increase with exercise. Ventilation in relation to oxygen consumption was higher in patients with failure than in control subjects.

  17. Characterization of Hemodynamics in Great Arteries of Wild-Type Mouse Using Computational Fluid Dynamics Based on Ultrasound Images.

    PubMed

    Chen, Zhuo; Zhou, Yue; Ma, Youcai; Wang, Jingying; He, Yihua; Li, Zhian

    2016-03-01

    Hemodynamic factors in cardiovascular system are hypothesized to play a significant role in causing structural heart development. It is thus important to improve our understanding of velocity characteristics and parameters. We present such a study on wild-type mouse to characterize the vessel geometry, flow pattern, and wall shear stress in great arteries. Microultrasound imaging for small animals was used to measure blood boundary and velocity of the great arteries. Subsequently, specimens' flow boundary conditions were used for 3-dimensional reconstructions of the great artery and aortic arch dimensions, and blood flow velocity data were input into subject-specific computational fluid dynamics for modeling hemodynamics. Measurement by microultrasound imaging showed that blood velocities in the great artery and aortic arch had strong correlations with vascular sizes, whereas blood pressure had a weak trend in relation to vascular size. Wall shear stress magnitude increased when closer to arterial branches and reduced proximally in the aortic root and distally in the descending aorta, and the parameters were related to the fluid mechanics in branches in some degree. We developed a method to investigate fluid mechanics in mouse arteries, using a combination of microultrasound and computational fluid dynamics, and demonstrated its ability to reveal detailed geometric, kinematic, and fluid mechanics parameters.

  18. A Longitudinal Study of Remodeling in a Revised Peripheral Artery Bypass Graft Using 3D Ultrasound Imaging and Computational Hemodynamics

    PubMed Central

    Leotta, Daniel F.; Beach, Kirk W.; Riley, James J.; Aliseda, Alberto

    2011-01-01

    We report a study of the role of hemodynamic shear stress in the remodeling and failure of a peripheral artery bypass graft. Three separate scans of a femoral to popliteal above-knee bypass graft were taken over the course of a 16 month period following a revision of the graft. The morphology of the lumen is reconstructed from data obtained by a custom 3D ultrasound system. Numerical simulations are performed with the patient-specific geometries and physiologically realistic flow rates. The ultrasound reconstructions reveal two significant areas of remodeling: a stenosis with over 85% reduction in area, which ultimately caused graft failure, and a poststenotic dilatation or widening of the lumen. Likewise, the simulations reveal a complicated hemodynamic environment within the graft. Preliminary comparisons with in vivo velocimetry also showed qualitative agreement with the flow dynamics observed in the simulations. Two distinct flow features are discerned and are hypothesized to directly initiate the observed in vivo remodeling. First, a flow separation occurs at the stenosis. A low shear recirculation region subsequently develops distal to the stenosis. The low shear region is thought to be conducive to smooth muscle cell proliferation and intimal growth. A poststenotic jet issues from the stenosis and subsequently impinges onto the lumen wall. The lumen dilation is thought to be a direct result of the high shear stress and high frequency pressure fluctuations associated with the jet impingement. PMID:21428682

  19. [Vasodilator therapy in pulmonary hypertension and chronic obstructive lung disease (COPD). Hemodynamic studies exemplified by nifedipine and nitroglycerin].

    PubMed

    Gassner, A; Fridrich, L; Magometschnigg, D; Sommer, G; Klicpera, M

    1986-08-01

    In 41 patients with chronic obstructive pulmonary disease (COPD) and pulmonary hypertension, the effects of sublingual administration of 20 mg nifedipine and 0.8 mg nitroglycerin on the hemodynamics were assessed at rest and during bicycle ergometry. Additionally, in six patients, the effects of nifedipine during longterm treatment were analyzed. On acute testing, at rest and during exercise nifedipine led to decreases in mean pulmonary artery pressure of 16% and 23% and pulmonary arteriolar resistance of 23 and 35%, respectively, in 81% (17/21) of the patients. The reduction in the pulmonary vascular resistance was greater than that of the systemic resistance. In all patients, cardiac output increased. There was a similar number of responders to nitroglycerin (16/20). The reductions in mean pulmonary artery pressure and pulmonary arteriolar resistance ranging between 20 and 25% at rest and during exercise were comparable to those affected by nifedipine. In addition to the right ventricular afterload reduction, there was a decrease in cardiac output of 17%. During longterm treatment with nifedipine (average 18 months), the reduction in mean pulmonary artery pressure and pulmonary arteriolar resistance was not of the same magnitude as seen on acute testing. This may be due primarily to progression of the underlying disease since pulmonary function studies demonstrated an increase in the obstructive component. With the intention of circumventing or postponing the onset of right ventricular failure, the individual patient should undergo hemodynamic studies to delineate the optimal medication.

  20. Chronic monitoring of cortical hemodynamics in behaving, freely-moving rats using a miniaturized head-mounted optical microscope

    NASA Astrophysics Data System (ADS)

    Sigal, Iliya; Gad, Raanan; Koletar, Margaret; Ringuette, Dene; Stefanovic, Bojana; Levi, Ofer

    2016-03-01

    Growing interest within the neurophysiology community in assessing healthy and pathological brain activity in animals that are awake and freely-behaving has triggered the need for optical systems that are suitable for such longitudinal studies. In this work we report label-free multi-modal imaging of cortical hemodynamics in the somatosensory cortex of awake, freely-behaving rats, using a novel head-mounted miniature optical microscope. The microscope employs vertical cavity surface emitting lasers (VCSELs) at three distinct wavelengths (680 nm, 795 nm, and 850 nm) to provide measurements of four hemodynamic markers: blood flow speeds, HbO, HbR, and total Hb concentration, across a > 2 mm field of view. Blood flow speeds are extracted using Laser Speckle Contrast Imaging (LSCI), while oxygenation measurements are performed using Intrinsic Optical Signal Imaging (IOSI). Longitudinal measurements on the same animal are made possible over the course of > 6 weeks using a chronic window that is surgically implanted into the skull. We use the device to examine changes in blood flow and blood oxygenation in superficial cortical blood vessels and tissue in response to drug-induced absence-like seizures, correlating motor behavior with changes in blood flow and blood oxygenation in the brain.

  1. A longitudinal study of remodeling in a revised peripheral artery bypass graft using 3D ultrasound imaging and computational hemodynamics.

    PubMed

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

    2011-04-01

    We report a study of the role of hemodynamic shear stress in the remodeling and failure of a peripheral artery bypass graft. Three separate scans of a femoral to popliteal above-knee bypass graft were taken over the course of a 16 month period following a revision of the graft. The morphology of the lumen is reconstructed from data obtained by a custom 3D ultrasound system. Numerical simulations are performed with the patient-specific geometries and physiologically realistic flow rates. The ultrasound reconstructions reveal two significant areas of remodeling: a stenosis with over 85% reduction in area, which ultimately caused graft failure, and a poststenotic dilatation or widening of the lumen. Likewise, the simulations reveal a complicated hemodynamic environment within the graft. Preliminary comparisons with in vivo velocimetry also showed qualitative agreement with the flow dynamics observed in the simulations. Two distinct flow features are discerned and are hypothesized to directly initiate the observed in vivo remodeling. First, a flow separation occurs at the stenosis. A low shear recirculation region subsequently develops distal to the stenosis. The low shear region is thought to be conducive to smooth muscle cell proliferation and intimal growth. A poststenotic jet issues from the stenosis and subsequently impinges onto the lumen wall. The lumen dilation is thought to be a direct result of the high shear stress and high frequency pressure fluctuations associated with the jet impingement.

  2. Axial flow pump treatment during myocardial depression in calves: an invasive hemodynamic and echocardiographic tissue Doppler study.

    PubMed

    Hubbert, Laila; Peterzén, Bengt; Traff, Stefan; Janerot-Sjoberg, Birgitta; Ahn, Henrik

    2008-01-01

    The aim of this study was to investigate flow characteristics and myocardial function after implantation of an axial pump left ventricular assist device while varying afterload and during progressive myocardial depression. Ten calves were included, seven of which fulfilled the protocol. Invasive hemodynamic monitoring and echocardiography with color-coded systolic tissue Doppler velocity (TD velocity) were used during prepump conditions, at three different pump speeds, during modification of the systemic vascular resistance (SVR), and during increasing degrees of beta-blockade. The TD velocity decreased with the myocardial function whereas left ventricular size, fractional shortening, and pump speed did not correlate significantly with the TD velocity. The TD velocity correlated significantly with native stroke volume, heart rate, SVR and cardiac output but none of these alone could explain more than 20% of the changes in TD velocity. The axial flow pump studied is effective in unloading the severely depressed heart and has a high capacity for maintaining an adequate cardiac output, regardless of differing hemodynamic conditions, pump speed or decreasing LV function. Echocardiography with volumetric rendering and TD velocity imaging are valuable tools for monitoring and quantifying residual myocardial function during pump treatment.

  3. Circadian rhythms of renal hemodynamics in unanesthetized, unrestrained rats.

    PubMed

    Pons, M; Tranchot, J; L'Azou, B; Cambar, J

    1994-10-01

    Catheters were placed in the jugular vein and femoral artery of male Sprague-Dawley rats and connected to a specially designed perfusor for continuous constant infusion of 0.9% NaCl and a syringe to perform simultaneous and intermittent blood collections. This permitted continuous 24-h study of renal hemodynamics, estimated by inulin (Cin) and p-amino-hippuric acid (CPAH) clearances; Cin represents glomerular filtration rate and CPAH renal plasma flow. Animals were individually housed in metabolism cages in a controlled environment with light/dark 12:12 h. Urine was collected every 4 h (12:00, 16:00, 20:00, 24:00, 04:00, and 08:00) and blood sampled at the midpoint of urine collection periods. Urine and plasma sodium, potassium, inulin, and PAH were spectrophotometrically assessed. During continuous infusion of isotonic saline, Cin exhibited circadian changes with large decrease between 12:00 and 20:00 h (0.9 +/- 0.2 ml/min) and acrophase at 00:30 h. Rhythmicity in CPAH was similar with the minimum between 16:00 and 20:00 h (2.5 +/- 0.3 ml/min) and peak between 00:00 and 04:00 h (acrophase at 00:25 h). Water and electrolyte excretion were also circadian rhythmic with a similar nighttime enhancement and daytime minimum. Such circadian changes persisted during continuous 0.9% NaCl infusion for several consecutive days. The unanesthetized, unrestrained rat model enables investigations in renal chronopharmacology and chronotoxicology.

  4. Hemodynamic aspects of reduced platelet adhesion on bioinspired microstructured surfaces.

    PubMed

    Pham, Tam Thanh; Wiedemeier, Stefan; Maenz, Stefan; Gastrock, Gunter; Settmacher, Utz; Jandt, Klaus D; Zanow, Jürgen; Lüdecke, Claudia; Bossert, Jörg

    2016-09-01

    Occlusion by thrombosis due to the absence of the endothelial cell layer is one of the most frequent causes of failure of artificial vascular grafts. Bioinspired surface structures may have a potential to reduce the adhesion of platelets contributing to hemostasis. The aim of this study was to investigate the hemodynamic aspects of platelet adhesion, the main cause of thrombosis, on bioinspired microstructured surfaces mimicking the endothelial cell morphology. We tested the hypothesis that platelet adhesion is statistically significantly reduced on bioinspired microstructured surfaces compared to unstructured surfaces. Platelet adhesion as a function of the microstructure dimensions was investigated under flow conditions on polydimethylsiloxane (PDMS) surfaces by a combined experimental and theoretical approach. Platelet adhesion was statistically significantly reduced (by up to 78%; p≤0.05) on the microstructured PDMS surfaces compared to that on the unstructured control surface. Finite element method (FEM) simulations of blood flow dynamic revealed a micro shear gradient on the microstructure surfaces which plays a pivotal role in reducing platelet adhesion. On the surfaces with the highest differences of the shear stress between the top of the microstructures and the ground areas, platelet adhesion was reduced most. In addition, the microstructures help to reduce the interaction strength between fluid and surfaces, resulting in a larger water contact angle but no higher resistance to flow compared to the unstructured surface. These findings provide new insight into the fundamental mechanisms of reducing platelet adhesion on microstructured bioinspired surfaces and may lay the basis for the development of innovative next generation artificial vascular grafts with reduced risk of thrombosis.

  5. 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.

  6. 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.

  7. Hemodynamic changes and retrograde flow in LVAD failure.

    PubMed

    Giridharan, Guruprasad A; Koenig, Steven C; Soucy, Kevin G; Choi, Young; Pirbodaghi, Tohid; Bartoli, Carlo R; Monreal, Gretel; Sobieski, Michael A; Schumer, Erin; Cheng, Allen; Slaughter, Mark S

    2015-01-01

    In the event of left ventricular assist device (LVAD) failure, we hypothesized that rotary blood pumps will experience significant retrograde flow and induce adverse physiologic responses. Catastrophic LVAD failure was investigated in computer simulation with pulsatile, axial, and centrifugal LVAD, mock flow loop with pulsatile (PVAD) and centrifugal (ROTAFLOW), and healthy and chronic ischemic heart failure bovine models with pulsatile (PVAD), axial (HeartMate II), and centrifugal (HVAD) pumps. Simulated conditions were LVAD "off" with outflow graft clamped (baseline), LVAD "off" with outflow graft unclamped (LVAD failure), and LVAD "on" (5 L/min). Hemodynamics (aortic and ventricular blood pressures, LVAD flow, and left ventricular volume), echocardiography (cardiac volumes), and end-organ perfusion (regional blood flow microspheres) were measured and analyzed. Retrograde flow was observed with axial and centrifugal rotary pumps during LVAD failure in computer simulation (axial = -3.4 L/min, centrifugal = -2.8 L/min), mock circulation (pulsatile = -0.1 L/min, centrifugal = -2.7 L/min), healthy (pulsatile = -1.2 ± 0.3 L/min, axial = -2.2 ± 0.2 L/min, centrifugal = -1.9 ± 0.3 L/min), and ischemic heart failure (centrifugal = 2.2 ± 0.7 L/min) bovine models for all test conditions (p < 0.05). Differences between axial and centrifugal LVAD were statistically indiscernible. Retrograde flow increased ventricular end-systolic and end-diastolic volumes and workload, and decreased myocardial and end-organ perfusion during LVAD failure compared with baseline, LVAD support, and pulsatile LVAD failure.

  8. Hemodynamic variability and cerebrovascular control after transient cerebral ischemia

    PubMed Central

    Allan, Philip D; Faulkner, James; O’Donnell, Terrence; Lanford, Jeremy; Wong, Lai-kin; Saleem, Saqib; Woolley, Brandon; Lambrick, Danielle; Stoner, Lee; Tzeng, Yu-Chieh

    2015-01-01

    We investigated if hemodynamic variability, cerebral blood flow (CBF) regulation, and their interrelationships differ between patients with transient ischemic attack (TIA) and controls. We recorded blood pressure (BP) and bilateral middle cerebral artery flow velocity (MCAv) in a cohort of TIA patients (n = 17), and age-matched controls (n = 15). Spontaneous fluctuations in BP and MCAv were characterized by spectral power analysis, and CBF regu