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Exercise induced bradycardia

Natale Daniele Brunetti, Pier Luigi Pellegrino, Girolamo D'Arienzo, Rafel Sai, Luigi Ziccardi, Francesco Santoro, Antonio Gaglione, Matteo Di Biase
We report the case of a 38-year-old woman with history of syncope and polymorphic ventricular tachycardia; tachycardia was inducible at exercise stress test, not at electrophysiologic study. Phases of QT prolongation were found at ambulatory electrocardiogram monitoring. The woman came to our attention for periodic control of implantable loop recorder. Rest electrocardiogram at admission unexpectedly showed sinus bradycardia, junctional rhythm, and ventricular premature beats. Furthermore, loop recorder control revealed a short run of bidirectional tachycardia, not associated with syncope...
July 28, 2016: Journal of Electrocardiology
Sunil Jit R J Logantha, Mathis K Stokke, Andrew J Atkinson, Sanjay R Kharche, Sajida Parveen, Yawer Saeed, Ivar Sjaastad, Ole M Sejersted, Halina Dobrzynski
BACKGROUND: The sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2) pump is an important component of the Ca(2+)-clock pacemaker mechanism that provides robustness and flexibility to sinus node pacemaking. We have developed transgenic mice with reduced cardiac SERCA2 abundance (Serca2 KO) as a model for investigating SERCA2's role in sinus node pacemaking. METHODS AND RESULTS: In Serca2 KO mice, ventricular SERCA2a protein content measured by Western blotting was 75% (P < 0...
2016: Frontiers in Physiology
Carsten Walter Israel
Bradyarrhythmias cause symptoms such as syncope, dizziness, or exercise intolerance and lead to the implantation of > 100 000 pacemakers in Germany annually. They are caused either by sinus node dysfunction (sinus bradycardia, sinoatrial block, sinusarrest, preautomatic pauses in paroxysmal atrial fibrillation, chronotropic incompetence) or by atrioventricular (AV) conduction abnormalities (AV block, complex bundle branch block). Optimal therapy of bradycardia crucially depends on ECG documentation which frequently requires Holter monitoring in the case of intermittent bradycardia...
May 2016: Deutsche Medizinische Wochenschrift
Sarah E Petite, Bryan M Bishop, Vincent F Mauro
The pharmacology, pharmacokinetics, efficacy and safety of ivabradine are reviewed. Ivabradine is an oral medication that directly and selectively inhibits the hyperpolarization-activated cyclic-nucleotide gated funny (If) current in the sinoatrial node resulting in heart rate reduction. It has a plasma elimination half-life of 6 hours and is administered twice daily. Ivabradine is extensively metabolized by cytochrome P450 3A4, and its metabolism is affected by inducers and inhibitors of the 3A4 enzyme. Studies in patients with heart failure indicate that ivabradine improves surrogate markers such as exercise tolerance...
February 23, 2016: American Journal of Therapeutics
D M Porteiro Vázquez, M Perego, L Santos, M Gerou-Ferriani, M W S Martin, R A Santilli
OBJECTIVES: To document the electrocardiographic findings of vagally-induced paroxysmal atrial fibrillation following a presumed reflex syncopal episode in the dog. ANIMALS: Seven dogs with a syncopal episode followed by a paroxysm of atrial fibrillation recorded on a 24-hour Holter. METHODS: Twenty-four hour Holter monitors were retrospectively reviewed, analysing the cardiac rhythm associated with syncopal events. Each recording was analysed from 10 min before the syncopal episode to until 10 min after a normal sinus rhythm had returned...
March 2016: Journal of Veterinary Cardiology: the Official Journal of the European Society of Veterinary Cardiology
Pâmela Santana Daltro, Paula Santana Alves, Murilo Fagundes Castro, Carine M Azevedo, Juliana Fraga Vasconcelos, Kyan James Allahdadi, Luiz Antônio Rodrigues de Freitas, Bruno Solano de Freitas Souza, Ricardo Ribeiro Dos Santos, Milena Botelho Pereira Soares, Simone Garcia Macambira
BACKGROUND/OBJECTIVES: High fat diet (HFD) is a major contributor to the development of obesity and cardiovascular diseases due to the induction of cardiac structural and hemodynamic abnormalities. We used a model of diabetic cardiomyopathy in C57Bl/6 mice fed with a HFD to investigate the effects of granulocyte-colony stimulating factor (G-CSF), a cytokine known for its beneficial effects in the heart, on cardiac anatomical and functional abnormalities associated with obesity and type 2 diabetes...
2015: BMC Cardiovascular Disorders
Daphne M Mulders, Cecile C de Vos, Ilse Vosman, Michel J A M van Putten
PURPOSE: Vagus nerve stimulation (VNS) has been successfully applied to reduce seizure frequency in numerous patients with epilepsy. However, various side effects, including dyspnea and bradycardia have been reported, that appear exercise related in some patients. This pilot study aims to obtain insight in the cardiorespiratory effects of VNS during both rest and exercise. METHODS: Patients with a VNS device who experience side effects during exercise are compared with patients without side effects...
December 2015: Seizure: the Journal of the British Epilepsy Association
Iris del Castillo Velasco-Martínez, Claudia J Hernández-Camacho, Lía C Méndez-Rodríguez, Tania Zenteno-Savín
In mammalian tissues under hypoxic conditions, ATP degradation results in accumulation of purine metabolites. During exercise, muscle energetic demand increases and oxygen consumption can exceed its supply. During breath-hold diving, oxygen supply is reduced and, although oxygen utilization is regulated by bradycardia (low heart rate) and peripheral vasoconstriction, tissues with low blood flow (ischemia) may become hypoxic. The goal of this study was to evaluate potential differences in the circulating levels of purine metabolism components between diving and exercise in bottlenose dolphins (Tursiops truncatus)...
January 2016: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
Laiali Jurdi Chaar, Tatiana Pereira Alves, Alvaro Martins Batista Junior, Lisete Compagno Michelini
BACKGROUND: Exercise training (T) blunts functional deficits and renin-angiotensin system (RAS) hyperactivity in hypertensive individuals. There is no information on T-induced temporal changes of brain RAS. We evaluate now the simultaneous effects of T on functional responses and time course changes in the expression/activity of brain RAS components in autonomic cardiovascular-controlling areas. METHODS AND RESULTS: Spontaneously hypertensive rats (SHR) and age-matched normotensive controls (WKY) were trained for 0, 1, 2, 4, 8 and 12 weeks...
2015: PloS One
Sylvia Konstantinidou, Helen Soultanakis
Apnea after exercise may evoke a neurally mediated conflict that may affect apneic time and create a cardiovascular strain. The physiological responses, induced by apnea with face immersion in cold water (10 °C), after a 3-min exercise bout, at 85% of VO2max,were examined in 10 swimmers. A pre-selected 40-s apnea, completed after rest (AAR), could not be met after exercise (AAE), and was terminated with an agonal gasp reflex, and a reduction of apneic time, by 75%. Bradycardia was evident with immersion after both, 40-s of AAR and after AAE (P<0...
January 2016: Respiratory Physiology & Neurobiology
Eugen Brailoiu, Elena Deliu, Romeo A Sporici, G Cristina Brailoiu
Irisin is a newly identified hormone induced in muscle and adipose tissues by physical activity. This protein and its encoding gene have been identified in the brain; in addition, the precursor for irisin, FNDC5, can cross the blood-brain barrier. The fact that irisin is secreted during exercise together with the lower resting heart rate in athletes prompted us to investigate the effect of irisin on cardiac-projecting vagal neurons of nucleus ambiguus, a key regulatory site of heart rate. In vitro experiments in cultured nucleus ambiguus neurons indicate that irisin activates these neurons, inducing an increase in cytosolic Ca(2+) concentration and neuronal depolarization...
June 2015: Physiological Reports
Tamás Erdei, Svend Aakhus, Paolo Marino, Walter J Paulus, Otto A Smiseth, Alan G Fraser
Cardiopulmonary functional reserve measured as peak oxygen uptake is predicted better at rest by measures of cardiac diastolic function than by systolic function. Normal adaptations in the trained heart include resting bradycardia, increased LV end-diastolic volume and augmented early diastolic suction on exercise. In normal populations early diastolic relaxation declines with age and end-diastolic stiffness increases, but in healthy older subjects who have exercised throughout their lives diastolic function can be well preserved...
September 2015: Heart: Official Journal of the British Cardiac Society
Juliane Cruz Campos, Tiago Fernandes, Luiz Roberto Grassmann Bechara, Nathalie Alves da Paixão, Patricia Chakur Brum, Edilamar Menezes de Oliveira, Julio Cesar Batista Ferreira
BACKGROUND: We previously reported that exercise training (ET) facilitates the clearance of damaged proteins in heart failure. Here, we characterized the impact of ET on cardiac protein quality control during compensated ventricular hypertrophy in spontaneously hypertensive rats (SHR). METHODS AND RESULTS: SHR were randomly assigned into sedentary and swimming-trained groups. Sedentary SHR displayed cardiac hypertrophy with preserved ventricular function compared to normotensive rats, characterizing a compensated cardiac hypertrophy...
2015: Oxidative Medicine and Cellular Longevity
George E Billman, Kristen L Cagnoli, Thomas Csepe, Ning Li, Patrick Wright, Peter J Mohler, Vadim V Fedorov
The mechanisms responsible for exercise-induced reductions in baseline heart rate (HR), known as training bradycardia, remain controversial. Therefore, changes in cardiac autonomic regulation and intrinsic sinoatrial nodal (SAN) rate were evaluated using dogs randomly assigned to either a 10- to 12-wk exercise training (Ex, n = 15) or an equivalent sedentary period (Sed, n = 10). Intrinsic HR was revealed by combined autonomic nervous system (ANS) blockade (propranolol + atropine, iv) before and after completion of the study...
June 1, 2015: Journal of Applied Physiology
Terrie M Williams, Lee A Fuiman, Traci Kendall, Patrick Berry, Beau Richter, Shawn R Noren, Nicole Thometz, Michael J Shattock, Edward Farrell, Andy M Stamper, Randall W Davis
Unlike their terrestrial ancestors, marine mammals routinely confront extreme physiological and physical challenges while breath-holding and pursuing prey at depth. To determine how cetaceans and pinnipeds accomplish deep-sea chases, we deployed animal-borne instruments that recorded high-resolution electrocardiograms, behaviour and flipper accelerations of bottlenose dolphins (Tursiops truncatus) and Weddell seals (Leptonychotes weddellii) diving from the surface to >200 m. Here we report that both exercise and depth alter the bradycardia associated with the dive response, with the greatest impacts at depths inducing lung collapse...
2015: Nature Communications
R K Palma, C Paixao, Gl Shimojo, N Bernardes, Ca Barboza, Ab Lopes, K De Angelis, C Malfitano
PURPOSE: Exercise training is an important intervention non-pharmacological for attenuation of metabolic and cardiovascular dysfunctions triggered by the advent of menopause. However, it is not known whether previous exercise training intervention alters the physiological and medical complications of these. Thereby, the purpose of the present study was to investigate the effects of previous exercise training (PT) on metabolic and hemodynamic parameters and oxidative stress in ovariectomized rats...
July 15, 2014: Cardiovascular Research
Ilkka Heinonen, Nobuyuki Kudomi, Jukka Kemppainen, Antti Kiviniemi, Tommi Noponen, Matti Luotolahti, Pauliina Luoto, Vesa Oikonen, Hannu T Sipilä, Jaakko Kopra, Ilkka Mononen, Dirk J Duncker, Juhani Knuuti, Kari K Kalliokoski
Highly endurance-trained athlete's heart represents the most extreme form of cardiac adaptation to physical stress, but its circulatory alterations remain obscure. In the present study, myocardial blood flow (MBF), blood mean transit time (MTT), oxygen extraction fraction (OEF) and consumption (MVO2), and efficiency of cardiac work were quantified in highly trained male endurance athletes and control subjects at rest and during supine cycling exercise using [(15)O]-labeled radiotracers and positron emission tomography...
July 2014: Basic Research in Cardiology
Alicia D'Souza, Annalisa Bucchi, Anne Berit Johnsen, Sunil Jit R J Logantha, Oliver Monfredi, Joseph Yanni, Sukhpal Prehar, George Hart, Elizabeth Cartwright, Ulrik Wisloff, Halina Dobryznski, Dario DiFrancesco, Gwilym M Morris, Mark R Boyett
Endurance athletes exhibit sinus bradycardia, that is a slow resting heart rate, associated with a higher incidence of sinus node (pacemaker) disease and electronic pacemaker implantation. Here we show that training-induced bradycardia is not a consequence of changes in the activity of the autonomic nervous system but is caused by intrinsic electrophysiological changes in the sinus node. We demonstrate that training-induced bradycardia persists after blockade of the autonomous nervous system in vivo in mice and in vitro in the denervated sinus node...
2014: Nature Communications
Daniel Carvalho de Lima, Juliana Bohnen Guimarães, Gisele Vieira Rodovalho, Simonton Andrade Silveira, Andrea Siqueira Haibara, Cândido Celso Coimbra
Peripheral sympathetic overdrive in young obese subjects contributes to further aggravation of insulin resistance, diabetes, and hypertension, thus inducing worsening clinical conditions in adulthood. Exercise training has been considered a strategy to repair obesity autonomic dysfunction, thereby reducing the cardiometabolic risk. Therefore, the aim of this study was to assess the effect of early exercise training, starting immediately after weaning, on cardiac autonomic control in diet-induced obese rats...
August 2014: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Gustavo S Masson, Tassia S R Costa, Lidia Yshii, Denise C Fernandes, Pedro Paulo Silva Soares, Francisco R Laurindo, Cristoforo Scavone, Lisete C Michelini
Baroreflex dysfunction, oxidative stress and inflammation, important hallmarks of hypertension, are attenuated by exercise training. In this study, we investigated the relationships and time-course changes of cardiovascular parameters, pro-inflammatory cytokines and pro-oxidant profiles within the hypothalamic paraventricular nucleus of the spontaneously hypertensive rats (SHR). Basal values and variability of arterial pressure and heart rate and baroreflex sensitivity were measured in trained (T, low-intensity treadmill training) and sedentary (S) SHR at weeks 0, 1, 2, 4 and 8...
2014: PloS One
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