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Cardiac physiology

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https://www.readbyqxmd.com/read/27911784/%C3%AE-arrestin-mediates-the-frank-starling-mechanism-of-cardiac-contractility
#1
Dennis M Abraham, Robert T Davis, Chad M Warren, Lan Mao, Beata M Wolska, R John Solaro, Howard A Rockman
The Frank-Starling law of the heart is a physiological phenomenon that describes an intrinsic property of heart muscle in which increased cardiac filling leads to enhanced cardiac contractility. Identified more than a century ago, the Frank-Starling relationship is currently known to involve length-dependent enhancement of cardiac myofilament Ca(2+) sensitivity. However, the upstream molecular events that link cellular stretch to the length-dependent myofilament Ca(2+) sensitivity are poorly understood. Because the angiotensin II type 1 receptor (AT1R) and the multifunctional transducer protein β-arrestin have been shown to mediate mechanosensitive cellular signaling, we tested the hypothesis that these two proteins are involved in the Frank-Starling mechanism of the heart...
November 28, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27909538/pulmonary-vein-remodeling-following-atrial-fibrillation-ablation-implications-for-the-radiographic-diagnosis-of-pulmonary-vein-stenosis
#2
Faisal M Merchant Md, Mathew R Levy Bs, Shahriar Iravanian Md, Ramal M Weragoda Md, Edward C Clermont Md, Heval M Kelli Md, Robert L Eisner PhD, David Vadnais Md, Mikhael F El-Chami Md, Angel R Leon Md, David B Delurgio Md
Background: Pulmonary vein (PV) reverse remodeling has been recognized following atrial fibrillation (AF) ablation. However, the extent of physiologic reverse remodeling after AF ablation and the potential impact of reverse remodeling on the radiographic diagnosis of PV stenosis have not been well characterized. Methods: From January 2004 to February 2014, 186 patients underwent paired cardiac magnetic resonance imaging (MRI) to delineate PV orifice dimensions before and after (mean 109 ± 61 days) an initial AF ablation...
August 2016: Journal of Atrial Fibrillation
https://www.readbyqxmd.com/read/27909483/from-incidental-mechanically-induced-arrhythmias-to-reflex-defined-arrhythmogenicity-on-the-track-of-the-ternary-reflex-system-resemblance-to-the-infancy-of-new-era-or-rediscovery
#3
REVIEW
Petras Stirbys Md PhD
The underlying pathophysiology of supraventricular and ventricular arrhythmias remains a matter of intense investigation. Though evolving, the contemporary explanations do not encompass all aspects of arrhythmogenicity. An improved understanding of arrhythmia substrate is needed to augment therapeutic capabilities. Our observation and literature sources demonstrate relatively high incidence of transitory arrhythmias which are non-intentionally generated by the endocardial lead/catheter manipulation. These findings are interesting and potentially may crystallize the reflex-dependent proarrhythmic cardiac activity...
February 2016: Journal of Atrial Fibrillation
https://www.readbyqxmd.com/read/27908340/end-points-of-sepsis-resuscitation
#4
REVIEW
John C Greenwood, Clinton J Orloski
Resuscitation goals for the patient with sepsis and septic shock are to return the patient to a physiologic state that promotes adequate end-organ perfusion along with matching metabolic supply and demand. Ideal resuscitation end points should assess the adequacy of tissue oxygen delivery and oxygen consumption, and be quantifiable and reproducible. Despite years of research, a single resuscitation end point to assess adequacy of resuscitation has yet to be found. Thus, the clinician must rely on multiple end points to assess the patient's overall response to therapy...
February 2017: Emergency Medicine Clinics of North America
https://www.readbyqxmd.com/read/27907931/-koronararterienanomalien-diagnostik-und-klassifikation-auf-basis-der-ct-und-mrt-des-herzens-von-alcapa-bis-terminationsanomaliecoronary-artery-anomalies-diagnosis-and-classification-based-on-cardiac-ct-and-mri-cmr-from-alcapa-to-anomalies-of-termination
#5
Philipp Heermann, Walter Heindel, Christoph Schülke
Background Coronary artery anomalies encompass a clinically and anatomically variable spectrum including physiological variants and pathophysiologically relevant anomalies. The majority of the variants has no hemodynamic relevance and is often detected accidentally. The recognition of the rare and relevant anomalies that cause either relevant shunt volumes leading to myocardial ischemia or ventricular tachyarrhythmias with the risk of sudden cardiac death is of major importance. Methods This review is based on a literature search in PubMed conducted using the key words "coronary artery" and/or "anomaly" and/or "anomalous origin" and/or "myocardial bridging" and/or "coronary artery fistula" and/or "Bland-White-Garland" and/or "ALCAPA"...
December 1, 2016: RöFo: Fortschritte Auf Dem Gebiete der Röntgenstrahlen und der Nuklearmedizin
https://www.readbyqxmd.com/read/27905081/parasympathetic-cardio-regulation-during-social-interactions-in-individuals-with-obesity-the-influence-of-negative-body-image
#6
Anne Schrimpf, Jana Kube, Jane Neumann, Annette Horstmann, Arno Villringer, Michael Gaebler
Individuals with obesity in Western societies often face weight-related stigmatization and social exclusion. Recurrent exposure to prejudice and negative social feedback alters one's behavior in future social interactions. In this study, we aimed to investigate autonomic nervous system and affective responses to social interactions in individuals with obesity. Women and men with (n = 56) and without (n = 56) obesity participated in episodes of social inclusion and social exclusion using a virtual ball-tossing game...
November 30, 2016: Cognitive, Affective & Behavioral Neuroscience
https://www.readbyqxmd.com/read/27904993/molecular-mechanisms-of-heart-failure-insights-from-drosophila
#7
Shasha Zhu, Zhe Han, Yan Luo, Yulin Chen, Qun Zeng, Xiushan Wu, Wuzhou Yuan
Heart failure places an enormous burden on health and economic systems worldwide. It is a complex disease that is profoundly influenced by both genetic and environmental factors. Neither the molecular mechanisms underlying heart failure nor effective prevention strategies are fully understood. Fortunately, relevant aspects of human heart failure can be experimentally studied in tractable model animals, including the fruit fly, Drosophila, allowing the in vivo application of powerful and sophisticated molecular genetic and physiological approaches...
December 1, 2016: Heart Failure Reviews
https://www.readbyqxmd.com/read/27903582/threshold-levels-of-extracellular-l-arginine-that-trigger-nos-mediated-ros-rns-production-in-cardiac-ventricular-myocytes
#8
Jayalakshmi Ramachandran, R Daniel Peluffo
L-arginine (L-Arg) is the substrate for nitric oxide synthase (NOS) to produce nitric oxide (NO), a signaling molecule that is key in cardiovascular physiology and pathology. In cardiac myocytes, L-Arg is incorporated from the circulation through the functioning of system-y(+) cationic amino acid transporters. Depletion of L-Arg leads to NOS uncoupling, with O2 rather than L-Arg as terminal electron acceptor, resulting in superoxide formation. The reactive oxygen species (ROS) superoxide (O2•(-)), combined with NO, may lead to the production of the reactive nitrogen species (RNS) peroxynitrite (ONOO-), which is recognized as a major contributor to myocardial depression...
November 30, 2016: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/27902841/dynamical-effects-of-calcium-sensitive-potassium-currents-on-voltage-and-calcium-alternans
#9
Matthew Kennedy, Donald M Bers, Nipavan Chiamvimonvat, Daisuke Sato
Cardiac alternans is a precursor to life-threatening arrhythmias. Alternans can be caused by instability of the membrane voltage (Vm ), instability of the intracellular Ca (Cai ) cycling, or both. Vm dynamics and Cai dynamics are coupled via Ca-sensitive currents. In cardiac myocytes, there are several Ca-sensitive potassium (K) currents such as the slowly activating delayed rectifier current (IKs ) and the small conductance Ca-activated potassium (SK) current (ISK ). However, the role of these currents in the development of arrhythmias is not well understood...
November 30, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27899435/imaging-oxygen-metabolism-with-hyperpolarized-magnetic-resonance-a-novel-approach-for-cardiac-and-renal-function%C3%A2-assessement
#10
Marie Schroeder, Christoffer Lausten
Every tissue in the body critically depends on meeting its energetic demands with sufficient oxygen supply. Oxygen supply/demand imbalances underlie the diseases that inflict the greatest socioeconomic burden globally. The purpose of this review is to examine how hyperpolarized contrast media, used in combination with MR data acquisition methods, may advance our ability to assess oxygen metabolism non-invasively and thus improve management of clinical disease. We first introduce the concept of hyperpolarization and how hyperpolarized contrast media have been practically implemented to achieve translational and clinical research...
November 29, 2016: Bioscience Reports
https://www.readbyqxmd.com/read/27899365/prevalence-and-clinical-significance-of-discordant-changes-in-fractional-and-coronary-flow-reserve-after-elective-percutaneous-coronary-intervention
#11
Junji Matsuda, Tadashi Murai, Yoshihisa Kanaji, Eisuke Usui, Makoto Araki, Takayuki Niida, Sadamitsu Ichijyo, Rikuta Hamaya, Tetsumin Lee, Taishi Yonetsu, Mitsuaki Isobe, Tsunekazu Kakuta
BACKGROUND: Fractional flow reserve (FFR) and coronary flow reserve (CFR) are well-validated physiological indices; however, changes in FFR and CFR after percutaneous coronary intervention (PCI) remain elusive. We sought to evaluate these changes and to investigate whether physiological indices predict cardiac event-free survival after PCI. METHODS AND RESULTS: Physiological assessment of 220 stenoses from 220 patients was performed before and after PCI. The changes in FFR and CFR were studied, and factors associated with CFR change were investigated...
November 29, 2016: Journal of the American Heart Association
https://www.readbyqxmd.com/read/27899087/paradoxical-physiological-responses-to-propranolol-in-a-rett-syndrome-patient-a-case-report
#12
P J Santosh, L Bell, K Lievesley, J Singh, F Fiori
BACKGROUND: Rett Syndrome (RTT), caused by a loss-of-function in the epigenetic modulator: X-linked methyl-CpG binding protein 2 (MeCP2), is a pervasive neurological disorder characterized by compromised brain functions, anxiety, severe mental retardation, language and learning disabilities, repetitive stereotyped hand movements and developmental regression. An imbalance in the sympathetic and the parasympathetic nervous system (dysautonomia) and the resulting autonomic storms is a frequent occurrence in patients with RTT...
November 29, 2016: BMC Pediatrics
https://www.readbyqxmd.com/read/27898641/oral-contraceptive-use-dampens-physiological-adaptations-to-sprint-interval-training
#13
Mia A Schaumberg, David G Jenkins, Xanne A K Janse de Jonge, Lynne M Emmerton, Tina L Skinner
PURPOSE: Oral contraceptive (OC) use reduces peak aerobic capacity (V˙O2peak), however, whether it also influences adaptations to training has yet to be determined. This study aimed to examine the influence of OC use on peak performance [peak power output (PPO)] and physiological adaptations [V˙O2peak and peak cardiac output (Q˙peak)] following sprint interval training (SIT) in recreationally-active women. METHODS: Women taking an OC (n=25) or experiencing natural regular menstrual cycles (MC; n=16) completed an incremental exercise test to assess V˙O2peak, PPO, and Q˙peak before, immediately after, and four weeks following 12 sessions of SIT...
November 28, 2016: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/27896466/early-hemodynamic-assessment-and-treatment-of-elderly-patients-in-the-medical-icu
#14
Gorazd Voga, Lucija Gabršček-Parežnik
BACKGROUND AND OBJECTIVES: The aim of this retrospective study was to analyze differences in the initial hemodynamic assessment and its impact on the treatment in patients aged 80 years or older compared to younger patients during the first 6 h after admission to the medical intensive care unit (ICU). RESULTS: We analyzed 615 consecutive patients admitted to the medical ICU of which 124 (20%) were aged 80 years or more. The older group had a significantly higher acute physiology and chronic health evaluation (APACHE II) score, an overall mortality in the ICU and a presence of pre-existing cardiac disease...
November 28, 2016: Wiener Klinische Wochenschrift
https://www.readbyqxmd.com/read/27896244/adaptive-responses-of-cardiac-function-to-fetal-postural-change-as-gestational-age-increases
#15
Woo Jin Kim, Hye Jin Choi, Sun Young Yang, Boo Hae Koo, Ki Hoon Ahn, Geum Joon Cho, Soon Cheol Hong, Min-Jeong Oh, Hai-Joong Kim
OBJECTIVE: The cardiovascular system maintains homeostasis through a series of adaptive responses to physiological requirements. However, little is known about the adaptation of fetal cardiac function to gravity, according to gestational age. In the present study, we aimed to evaluate the adaptive responses of cardiac function to postural changes, using Tei index measurements. METHODS: Fetal echocardiography and Doppler examination were performed on 114 women with vertex singleton pregnancies at 19 to 40 weeks' gestation...
November 2016: Obstetrics & Gynecology Science
https://www.readbyqxmd.com/read/27896005/cerebral-blood-flow-is-decoupled-from-blood-pressure-and-linked-to-eeg-bursting-after-resuscitation-from-cardiac-arrest
#16
Christian Crouzet, Robert H Wilson, Afsheen Bazrafkan, Maryam H Farahabadi, Donald Lee, Juan Alcocer, Bruce J Tromberg, Bernard Choi, Yama Akbari
In the present study, we have developed a multi-modal instrument that combines laser speckle imaging, arterial blood pressure, and electroencephalography (EEG) to quantitatively assess cerebral blood flow (CBF), mean arterial pressure (MAP), and brain electrophysiology before, during, and after asphyxial cardiac arrest (CA) and resuscitation. Using the acquired data, we quantified the time and magnitude of the CBF hyperemic peak and stabilized hypoperfusion after resuscitation. Furthermore, we assessed the correlation between CBF and MAP before and after stabilized hypoperfusion...
November 1, 2016: Biomedical Optics Express
https://www.readbyqxmd.com/read/27895596/reciprocal-modulation-of-ik1-ina-extends-excitability-in-cardiac-ventricular-cells
#17
Anthony Varghese
The inwardly rectifying potassium current (IK1) and the fast inward sodium current (INa) are reciprocally modulated in mammalian ventricular myocytes. An increase in the expression of channels responsible for one of these two currents results in a corresponding increase in expression of the other. These currents are critical in the propagation of action potentials (AP) during the normal functioning of the heart. This study identifies a physiological role for IK1-INa reciprocal modulation in ventricular fiber activation thresholds and conduction...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27895589/amino-acid-changes-at-arginine-204-of-troponin-i-result-in-increased-calcium-sensitivity-of-force-development
#18
Susan Nguyen, Rylie Siu, Shannamar Dewey, Ziyou Cui, Aldrin V Gomes
Mutations in human cardiac troponin I (cTnI) have been associated with restrictive, dilated, and hypertrophic cardiomyopathies. The most commonly occurring residue on cTnI associated with familial hypertrophic cardiomyopathy (FHC) is arginine (R), which is also the most common residue at which multiple mutations occur. Two FHC mutations are known to occur at cTnI arginine 204, R204C and R204H, and both are associated with poor clinical prognosis. The R204H mutation has also been associated with restrictive cardiomyopathy (RCM)...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27893988/endothelin-signaling-in-bone
#19
REVIEW
Jasmin Kristianto, Michael G Johnson, Rafia Afzal, Robert D Blank
The endothelin (ET) system includes 3 small peptide hormones and a pair of G protein-coupled receptors. All 3 ETs are secreted as biologically inert precursors that must be activated by proteolytic cleavage after secretion. This reaction can be catalyzed by a pair of specific, membrane-bound extracellular ET converting enzymes or by nonspecific tissue proteases. The ET1/EDNRA axis is essential in development, with knockout mice for either displaying a similar phenotype featuring multiple defects of the craniofacial skeleton and cardiac outflow tract...
November 11, 2016: Translational Research: the Journal of Laboratory and Clinical Medicine
https://www.readbyqxmd.com/read/27893645/preperitoneal-pelvic-packing-reduces-mortality-in-patients-with-life-threatening-hemorrhage-due-to-unstable-pelvic-fractures
#20
Clay Cothren Burlew, Ernest E Moore, Philip F Stahel, Andrea E Geddes, Amy E Wagenaar, Fredric M Pieracci, Charles J Fox, Eric M Campion, Jeffrey L Johnson, Cyril Mauffrey
BACKGROUND: A 2015 AAST trial reported a 32% mortality for pelvic fracture patients in shock. Angioembolization (AE) is the most common intervention; the Maryland group revealed time to AE averaged 5 hours. The goal of this study was to evaluate the time to intervention and outcomes of an alternative approach for pelvic hemorrhage. We hypothesized preperitoneal pelvic packing (PPP) results in a shorter time to intervention and lower mortality. METHODS: In 2004 we initiated a PPP protocol for pelvic fracture hemorrhage...
November 23, 2016: Journal of Trauma and Acute Care Surgery
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