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Circulatory physiology

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https://www.readbyqxmd.com/read/28086779/the-effect-of-electrical-conductivity-of-myocardium-on-cardiac-pumping-efficacy-a-computational-study
#1
Ana Rahma Yuniarti, Ki Moo Lim
BACKGROUND AND AIMS: The existence of non-excitable cells in the myocardium leads to the increasing conduction non-uniformity and decreasing myocardial electrical conductivity. Slowed myocardial conduction velocity (MCV) believed to enhance the probability of cardiac arryhthmia and alter the cardiac mechanical pumping efficacy, even in sinus rhythm. Though several studies on the correlation between MCV and cardiac electrical instabilities exist, there has been no study concerning correlation or causality between MCV and cardiac mechanical pumping efficacy, due to the limitation in clinical methods to document and evaluate cardiac mechanical responses directly...
January 10, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28079659/suspected-malignant-hyperthermia-in-the-setting-of-hypothermic-circulatory-arrest-for-type-a-aortic-dissection-repair-a-case-report
#2
Bryant Bunting, Joshua Knight, Stephen M McHugh
Malignant Hyperthermia (MH) is a life-threatening biochemical process of hypermetabolism brought about in susceptible individuals by a triggering drug or event. Type A aortic dissections are surgical emergencies requiring cardiopulmonary bypass and frequently deep hypothermic circulatory arrest. We present a case of suspected MH in a patient undergoing emergent repair of a type A aortic dissection. Upon arrival at our institution, the patient had multiple signs of MH. However, no known triggering agent had been administered...
January 11, 2017: A & A Case Reports
https://www.readbyqxmd.com/read/28079557/dobutamine-aggravates-haemodynamic-deterioration-induced-by-pleural-effusion-a-randomised-controlled-porcine-study
#3
Kristian B Wemmelund, Anders H Sørensen, Viktor K Ringgård, Erik Sloth, Peter Juhl-Olsen
BACKGROUND: Pleural effusion is a common finding in critically ill patients and may contribute to circulatory instability and the need for inotropic support. OBJECTIVE: We hypothesised that dobutamine would affect the physiological determinants preload, afterload, contractility and changes of inferior vena cava characteristics during experimental pleural effusion. DESIGN: A randomised, controlled laboratory study. SETTING: Animal laboratory, conducted from March 2013 to May 2013...
January 11, 2017: European Journal of Anaesthesiology
https://www.readbyqxmd.com/read/28077626/low-dose-or-low-dose-rate-ionizing-radiation-induced-bioeffects-in-animal-models
#4
REVIEW
Feng Ru Tang, Weng Keong Loke, Boo Cheong Khoo
Animal experimental studies indicate that acute or chronic low-dose ionizing radiation (LDIR) (≤100 mSv) or low-dose-rate ionizing radiation (LDRIR) (<6 mSv/h) exposures may be harmful. It induces genetic and epigenetic changes and is associated with a range of physiological disturbances that includes altered immune system, abnormal brain development with resultant cognitive impairment, cataractogenesis, abnormal embryonic development, circulatory diseases, weight gain, premature menopause in female animals, tumorigenesis and shortened lifespan...
January 10, 2017: Journal of Radiation Research
https://www.readbyqxmd.com/read/28069939/real-time-measurement-of-small-molecules-directly-in-awake-ambulatory-animals
#5
Netzahualcóyotl Arroyo-Currás, Jacob Somerson, Philip A Vieira, Kyle L Ploense, Tod E Kippin, Kevin W Plaxco
The development of a technology capable of tracking the levels of drugs, metabolites, and biomarkers in the body continuously and in real time would advance our understanding of health and our ability to detect and treat disease. It would, for example, enable therapies guided by high-resolution, patient-specific pharmacokinetics (including feedback-controlled drug delivery), opening new dimensions in personalized medicine. In response, we demonstrate here the ability of electrochemical aptamer-based (E-AB) sensors to support continuous, real-time, multihour measurements when emplaced directly in the circulatory systems of living animals...
January 9, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28060323/a-model-to-simulate-clinically-relevant-hypoxia-in-humans
#6
Lars Eichhorn, Florian Kessler, Volker Böhnert, Felix Erdfelder, Anja Reckendorf, Rainer Meyer, Richard K Ellerkmann
In case of apnea, arterial partial pressure of oxygen (pO2) decreases, while partial pressure of carbon dioxide (pCO2) increases. To avoid damage to hypoxia sensitive organs such as the brain, compensatory circulatory mechanisms help to maintain an adequate oxygen supply. This is mainly achieved by increased cerebral blood flow. Intermittent hypoxia is a commonly seen phenomenon in patients with obstructive sleep apnea. Acute airway obstruction can also result in hypoxia and hypercapnia. Until now, no adequate model has been established to simulate these dynamics in humans...
December 22, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28050890/nanoengineered-strategies-for-sirna-delivery-from-target-assessment-to-cancer-therapeutic-efficacy
#7
REVIEW
Dinesh Kumar Mishra, Neelam Balekar, Pradyumna Kumar Mishra
The promise of RNA interference (RNAi) technology in cancer therapeutics aims to deliver small interfering RNA (siRNA) for silencing of gene expression in cell type-specific pathway. However, the challenge for the delivery of stable siRNA is hindered by an immune-hostile tumor microenvironment and physiological barriers of the circulatory system. Therefore, the development and validation of safe, stable, and efficient nanoengineered delivery systems are highly essential for effective delivery of siRNA into cancer cells...
January 3, 2017: Drug Delivery and Translational Research
https://www.readbyqxmd.com/read/28012642/postoperative-cerebral-and-somatic-near-infrared-spectroscopy-saturations-and-outcome-in-hypoplastic-left-heart-syndrome
#8
George M Hoffman, Nancy S Ghanayem, John P Scott, James S Tweddell, Michael E Mitchell, Kathleen A Mussato
BACKGROUND: Circulatory vulnerability reflected by low systemic venous oxygen saturation after surgical palliation of hypoplastic left heart syndrome predicts adverse neurologic outcome and reduced survival, and targeting venous saturation may improve outcome. We herein test the hypothesis that near-infrared spectroscopy (NIRS)-derived cerebral and somatic/renal regional saturations can predict survival. METHODS: Patient data, from a prospective Institutional Review Board-approved registry of hemodynamic measures after initial palliation of hypoplastic left heart syndrome, were analyzed with logistic and multivariable mixed regression methods to determine relationships between standard hemodynamic measures, direct and NIRS measures of saturation, and outcome...
December 21, 2016: Annals of Thoracic Surgery
https://www.readbyqxmd.com/read/28008209/paradigm-shifts-in-ophthalmic-diagnostics
#9
J Sebag, Alfredo A Sadun, Eric A Pierce
PURPOSE: Future advances in ophthalmology will see a paradigm shift in diagnostics from a focus on dysfunction and disease to better measures of psychophysical function and health. Practical methods to define genotypes will be increasingly important and non-invasive nanotechnologies are needed to detect molecular changes that predate histopathology. METHODS: This is not a review nor meant to be comprehensive. Specific topics have been selected to illustrate the principles of important paradigm shifts that will influence the future of ophthalmic diagnostics...
August 2016: Transactions of the American Ophthalmological Society
https://www.readbyqxmd.com/read/27999072/the-extracellular-isoform-of-superoxide-dismutase-has-a-significant-impact-on-cardiovascular-ischaemia-and-reperfusion-injury-during-cardiopulmonary-bypass
#10
Antonio Pinto, Moritz Benjamin Immohr, Annika Jahn, Alexander Jenke, Udo Boeken, Artur Lichtenberg, Payam Akhyari
OBJECTIVES: Cardiac surgery with cardiopulmonary bypass (CPB) provokes ischaemia and reperfusion injury (IRI). Superoxide is a main mediator of IRI and is detoxified by superoxide dismutases (SODs). Extracellular SOD (SOD3) is the prevailing isoform in the cardiovascular system. Its mutation is associated with elevated risk for ischaemic heart disease as epidemiological and experimental studies suggest. We investigated the influence of SOD3 on IRI in the context of CPB and hypothesized a protective role for this enzyme...
December 2016: European Journal of Cardio-thoracic Surgery
https://www.readbyqxmd.com/read/27989869/the-physiology-of-continuous-flow-left-ventricular-assist-devices
#11
REVIEW
Hoong Sern Lim, Neil Howell, Aaron Ranasinghe
The use of left ventricular assist devices (LVADs) has increased significantly over the last few years, in part because heart transplant activity has plateaued, but also the improving clinical outcomes with contemporary continuous flow LVAD. As such, there is now a growing population of patients with continuous flow LVADs. Management of these patients is complicated by the altered circulatory physiology, as continuous flow LVADs provide a parallel circulation from the heart to the aorta, which interacts with the native left heart (systemic) circulation with consequent effects on the right heart circulation...
October 28, 2016: Journal of Cardiac Failure
https://www.readbyqxmd.com/read/27989868/extracorporeal-life-support-physiological-concepts-and-clinical-outcomes
#12
REVIEW
Hoong Sern Lim, Neil Howell, Aaron Ranasinghe
Extracorporeal life support (ECLS) describes a system that involves drainage from the venous circulation and return via an oxygenator into the arterial circulation (veno-arterial extracorporeal membrane oxygenation). ECLS provides effective cardiopulmonary support, but the parallel circulation has complex effects on the systemic and pulmonary circulatory physiology. An understanding of the physiological changes is fundamental to the management of ECLS. In this review, the key physiological concepts and the implications on the clinical management of ECLS are discussed...
October 27, 2016: Journal of Cardiac Failure
https://www.readbyqxmd.com/read/27968776/the-electrocardiogram-of-the-neonate-and-infant
#13
Konrad Brockmeier, Rewa Nazal, Narayanswami Sreeram
The ECG in children has a number of characteristic differences compared to the ECG of the adult. The transition of the ECG in neonates after birth represents dynamic changes of the circulatory system due to the postnatal adaptation, different physiologic properties of the fetal and neonatal myocardium, the location and orientation of the heart in the chest and influence of body mass during that period and later on in childhood. The complexity of the changes implies a broad variation of ECG changes during the first days and weeks of life, whose interpretation requires expert knowledge...
November 2016: Journal of Electrocardiology
https://www.readbyqxmd.com/read/27965040/hemodynamic-shear-stress-stimulates-migration-and-extravasation-of-tumor-cells-by-elevating-cellular-oxidative-level
#14
Shijun Ma, Afu Fu, Geraldine Giap Ying Chiew, Kathy Qian Luo
Cancer cells are shed into the blood stream and are exposed to hemodynamic shear stress during metastasis. It has been shown that shear stress can destroy circulating tumor cells (CTCs) both in vitro and in vivo. However, it remains unclear whether shear stress can modulate the properties and functions of tumor cells in a manner that might help CTCs to exit circulation. In this study, we established a microfluidic circulatory system to apply physiological fluid shear stress on breast cancer cells and demonstrated that an arterial level of shear stress significantly enhanced tumor cell migration in transwell and wound healing assays, and enhanced extravasation in a transendothelial assay...
December 10, 2016: Cancer Letters
https://www.readbyqxmd.com/read/27943010/special-section-medical-imaging-and-insights-into-the-mechanics-of-heart-and-circulatory-physiology-and-dysfunction
#15
(no author information available yet)
No abstract text is available yet for this article.
December 9, 2016: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/27935084/a-physical-heart-failure-simulation-system-utilizing-the-total-artificial-heart-and-modified-donovan-mock-circulation
#16
Jessica R Crosby, Katrina J DeCook, Phat L Tran, Edward Betterton, Richard G Smith, Douglas F Larson, Zain I Khalpey, Daniel Burkhoff, Marvin J Slepian
With the growth and diversity of mechanical circulatory support (MCS) systems entering clinical use, a need exists for a robust mock circulation system capable of reliably emulating and reproducing physiologic as well as pathophysiologic states for use in MCS training and inter-device comparison. We report on the development of such a platform utilizing the SynCardia Total Artificial Heart and a modified Donovan Mock Circulation System, capable of being driven at normal and reduced output. With this platform, clinically relevant heart failure hemodynamics could be reliably reproduced as evidenced by elevated left atrial pressure (+112%), reduced aortic flow (-12...
December 9, 2016: Artificial Organs
https://www.readbyqxmd.com/read/27925228/a-mock-circulatory-system-incorporating-a-compliant-3d-printed-anatomical-model-to-investigate-pulmonary-hemodynamics
#17
Paul G M Knoops, Giovanni Biglino, Alun D Hughes, Kim H Parker, Linzhang Xu, Silvia Schievano, Ryo Torii
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...
December 7, 2016: Artificial Organs
https://www.readbyqxmd.com/read/27908338/fluid-resuscitation-in-severe-sepsis
#18
REVIEW
Rob Loflin, Michael E Winters
Since its original description in 1832, fluid resuscitation has become the cornerstone of early and aggressive treatment of severe sepsis and septic shock. However, questions remain about optimal fluid composition, dose, and rate of administration for critically ill patients. This article reviews pertinent physiology of the circulatory system, pathogenesis of septic shock, and phases of sepsis resuscitation, and then focuses on the type, rate, and amount of fluid administration for severe sepsis and septic shock, so providers can choose the right fluid, for the right patient, at the right time...
February 2017: Emergency Medicine Clinics of North America
https://www.readbyqxmd.com/read/27906830/heterotopic-abdominal-rat-heart-transplantation-as-a-model-to-investigate-volume-dependency-of-myocardial-remodeling
#19
Kálmán Benke, Alex Ali Sayour, Csaba Mátyás, Bence Ágg, Balázs Tamás Németh, Attila Oláh, Mihály Ruppert, István Hartyánszky, Zoltán Szabolcs, Tamás Radovits, Béla Merkely, Gábor Szabó
Heterotopic abdominal rat heart transplantation has been extensively used to investigate ischemic/reperfusion injury, immunological consequences during heart transplantations and also to study remodeling of the myocardium due to volume unloading. We provide a unique review on the latter and present a summary of the experimental studies on rat heart transplantation to illustrate changes that occur to the myocardium due to volume unloading. We divided the literature based on whether normal or failing rat heart models were used...
December 1, 2016: Transplantation
https://www.readbyqxmd.com/read/27898678/leukocyte-telomere-length-in-relation-to-17-biomarkers-of-cardiovascular-disease-risk-a-cross-sectional-study-of-us-adults
#20
David H Rehkopf, Belinda L Needham, Jue Lin, Elizabeth H Blackburn, Ami R Zota, Janet M Wojcicki, Elissa S Epel
BACKGROUND: Leukocyte telomere length (LTL) is a putative biological marker of immune system age, and there are demonstrated associations between LTL and cardiovascular disease. This may be due in part to the relationship of LTL with other biomarkers associated with cardiovascular disease risk. However, the strength of associations between LTL and adiposity, metabolic, proinflammatory, and cardiovascular biomarkers has not been systematically evaluated in a United States nationally representative population...
November 2016: PLoS Medicine
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