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Early repolarization

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https://www.readbyqxmd.com/read/28940628/identification-of-electrocardiographic-risk-markers-for-the-initial-and-recurrent-episodes-of-ventricular-fibrillation-in-patients-with-brugada-syndrome
#1
Hiroshi Morita, Atsuyuki Watanabe, Satoshi Kawada, Masakazu Miyamoto, Yoshimasa Morimoto, Koji Nakagawa, Nobuhiro Nishii, Kazufumi Nakamura, Hiroshi Ito
INTRODUCTION: New onset of ventricular fibrillation (VF) in asymptomatic patients with Brugada-type ECG is not frequent, but it cannot be negligible. Risk markers for predicting VF are usually based on results of analysis in symptomatic patients, and they have not been determined for asymptomatic patients. We analyzed ECG markers in patients with Brugada syndrome to differentiate the risk factors for VF in both symptomatic and asymptomatic patients. METHODS: The subjects were 471 patients with Brugada syndrome and we divided the subjects into two groups: Asymptomatic group (n = 326) and Symptomatic group (syncope: n = 122, VF: n = 23)...
September 22, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28931785/ventricular-fibrillation-due-to-early-repolarization-syndrome-in-the-wake-of-hypothermia-due-to-fulminant-acute-disseminated-encephalomyelitis
#2
Kyoichiro Yazaki, Yoichi Ajiro, Kunihiko Shimizu, Fumiaki Mori, Nobue Yagihara, Akinori Sato, Tatsuya Takahashi, Kazunori Iwade
No abstract text is available yet for this article.
September 20, 2017: Circulation Journal: Official Journal of the Japanese Circulation Society
https://www.readbyqxmd.com/read/28930854/a-female-patient-with-hypokalaemia-induced-j-wave-syndrome-an-unusual-case-report
#3
Aqian Wang, Xiang Li, Muhammad Nabeel Dookhun, Tiancheng Zhang, Ping Xie, Yunshan Cao
RATIONALE: Prominent J waves can be seen in life-threatening cardiac arrhythmias such as Brugada syndrome, early repolarization syndrome, and ventricular fibrillation. We herein present an unusual case report of hypokalemia-induced J wave syndrome and ST (a part of ECG) segment elevation. PATIENTS CONCERNS: A 52-year-old woman with chief complaints of chest pain for 2 hours and diarrhea showed a marked hypokalemia (2.8 mmol/L) and slightly elevated creatine kinase-MB (CK-MB) (57...
September 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28927316/cardiovascular-magnetic-resonance-detects-silent-heart-disease-missed-by-echocardiography-in-systemic-lupus-erythematosus
#4
S Mavrogeni, L Koutsogeorgopoulou, G Markousis-Mavrogenis, A Bounas, M Tektonidou, S-N C Lliossis, D Daoussis, S Plastiras, G Karabela, E Stavropoulos, G Katsifis, V Vartela, G Kolovou
Background Accurate diagnosis of cardiovascular involvement in systemic lupus erythematosus (SLE) remains challenging, due to limitations of echocardiography. We hypothesized that cardiovascular magnetic resonance can detect cardiac lesions missed by echocardiography in SLE patients with atypical symptoms. Aim To use cardiovascular magnetic resonance in SLE patients with atypical symptoms and investigate the possibility of silent heart disease, missed by echocardiography. Patients/methods From 2005 to 2015, 80 SLE patients with atypical cardiac symptoms/signs (fatigue, mild shortness of breath, early repolarization and sinus tachycardia) aged 37 ± 6 years (72 women/8 men), with normal echocardiography, were evaluated using a 1...
January 1, 2017: Lupus
https://www.readbyqxmd.com/read/28924617/dynamics-of-sodium-current-mediated-early-afterdepolarizations
#5
Daisuke Sato, Colleen E Clancy, Donald M Bers
Early afterdepolarizations (EADs) have been attributed to two primary mechanisms: 1) recovery from inactivation of the L-type calcium (Ca) channel and/or 2) spontaneous Ca release, which depolarizes the membrane potential through the electrogenic sodium-calcium exchanger (NCX). The sodium (Na) current (INa), especially the late component of the Na current, has been recognized as an important player to set up the conditions for EADs by reducing repolarization reserve and increasing intracellular Na concentration, which leads to Ca overload...
September 2017: Heliyon
https://www.readbyqxmd.com/read/28919864/%C3%AE-subunits-control-the-effects-of-human-kv4-3-potassium-channel-phosphorylation
#6
Geoffrey W Abbott
The transient outward K(+) current, Ito, activates early in the cardiac myocyte action potential, to begin repolarization. Human Ito is generated primarily by two Kv4.3 potassium channel α subunit splice variants (Kv4.3L and Kv4.3S) that diverge only by a C-terminal, membrane-proximal, 19-residue stretch unique to Kv4.3L. Protein kinase C (PKC) phosphorylation of threonine 504 within the Kv4.3L-specific 19-residues mediates α-adrenergic inhibition of Ito in human heart. Kv4.3 is regulated in human heart by various β subunits, including cytosolic KChIP2b and transmembrane KCNEs, yet their impact on the functional effects of human Kv4...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28898995/uncovering-the-arrhythmogenic-potential-of-trpm4-activation-in-atrial-derived-hl-1-cells-using-novel-recording-and-numerical-approaches
#7
Yaopeng Hu, Yubin Duan, Ayako Takeuchi, Lin Hai-Kurahara, Jun Ichikawa, Keizo Hiraishi, Tomohiro Numata, Hiroki Ohara, Gentaro Iribe, Michio Nakaya, Masayuki X Mori, Satoshi Matsuoka, Genshan Ma, Ryuji Inoue
Aims: Transient receptor potential cation channel subfamily melastatin member 4 (TRPM4), a Ca2+-activated nonselective cation channel abundantly expressed in the heart, has been implicated in conduction block and other arrhythmic propensities associated with cardiac remodelling and injury. The present study aimed to quantitatively evaluate the arrhythmogenic potential of TRPM4. Methods and results: Patch clamp and biochemical analyses were performed using expression system and an immortalized atrial cardiomyocyte cell line (HL-1), and numerical model simulation was employed...
August 1, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28868038/quantitative-comparison-of-effects-of-dofetilide-sotalol-quinidine-and-verapamil-between-human-ex-vivo-trabeculae-and-in-silico-ventricular-models-incorporating-inter-individual-action-potential-variability
#8
Oliver J Britton, Najah Abi-Gerges, Guy Page, Andre Ghetti, Paul E Miller, Blanca Rodriguez
Background:In silico modeling could soon become a mainstream method of pro-arrhythmic risk assessment in drug development. However, a lack of human-specific data and appropriate modeling techniques has previously prevented quantitative comparison of drug effects between in silico models and recordings from human cardiac preparations. Here, we directly compare changes in repolarization biomarkers caused by dofetilide, dl-sotalol, quinidine, and verapamil, between in silico populations of human ventricular cell models and ex vivo human ventricular trabeculae...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28842979/epicardial-ablation-utilising-remote-magnetic-navigation-in-a-patient-with-brugada-syndrome-and-inferior-early-repolarisation
#9
Paul Chun Yih Lim, Koonlawee Nademanee, Edward Chun Yi Lee, Wee Siong Teo
We report a case of epicardial ablation in a combined Brugada and inferior early repolarization syndrome patient with recurrent defibrillator therapy for spontaneous VF. Electroanatomic mapping and ablation were achieved with remote magnetic navigation. Highly fractionated electrograms were seen epicardially in the anterior RVOT and at the anterior-inferior right ventricle. Ablation of the RVOT region resulted in resolution Brugada pattern ECG. The inferior early repolarisation persisted despite ablation of the inferior right ventricular epicardium...
August 26, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28815597/cardiac-action-potential-repolarization-re-visited-early-repolarization-shows-all-or-none-behaviour
#10
Beatriz Trenor, Karen Cardona, Javier Saiz, Denis Noble, Wayne Giles
In healthy mammalian hearts the action potential (AP) waveform initiates and modulates each contraction, or heartbeat. As a result, action potential height and duration are key physiological variables. In addition, rate-dependent changes in ventricular action potential duration (APD), and variations in APD at a fixed heart rate, are both reliable biomarkers of electrophysiological stability. Present guidelines for the likelihood that candidate drugs will increase arrhythmias rely on small changes in APD and Q-T intervals as criteria for Safety Pharmacology decisions...
August 17, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28797161/masked-inherited-primary-arrhythmia-syndromes-in-sudden-cardiac-death-patients-accompanied-by-coronary-vasospasm
#11
Ki Hong Lee, Hyung Wook Park, Jeong Nam Eun, Jeong Gwan Cho, Nam Sik Yoon, Mi Ran Kim, Yo Han Ku, Hyukjin Park, Seung Hun Lee, Jeong Han Kim, Min Chul Kim, Woo Jin Kim, Hyun Kuk Kim, Jae Yeong Cho, Keun-Ho Park, Doo Sun Sim, Hyun Ju Yoon, Kye Hun Kim, Young Joon Hong, Ju Han Kim, Youngkeun Ahn, Myung Ho Jeong, Jong Chun Park
BACKGROUND/AIMS: Coronary vasospasms are one of the important causes of sudden cardiac death (SCD). Provocation of coronary vasospasms can be useful, though some results may lead to false positives, with patients potentially experiencing recurrent SCD despite appropriate medical treatments. We hypothesized that it is not coronary vasospasms but inherited primary arrhythmia syndromes (IPAS) that underlie the development of SCD. METHODS: We analyzed 74 consecutive patients (3...
September 2017: Korean Journal of Internal Medicine
https://www.readbyqxmd.com/read/28756335/computational-approaches-to-understand-the-adverse-drug-effect-on-potassium-sodium-and-calcium-channels-for-predicting-tdp-cardiac-arrhythmias
#12
Mohsen Sharifi
Ion channels play a crucial role in the cardiovascular system. Our understanding of cardiac ion channel function has improved since their first discoveries. The flow of potassium, sodium and calcium ions across cardiomyocytes is vital for regular cardiac rhythm. Blockage of these channels, delays cardiac repolarization or tend to shorten repolarization and may induce arrhythmia. Detection of drug risk by channel blockade is considered essential for drug regulators. Advanced computational models can be used as an early screen for torsadogenic potential in drug candidates...
July 8, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28746852/photo-cross-linking-of-iks-demonstrates-state-dependent-interactions-between-kcne1-and-kcnq1
#13
Maartje Westhoff, Christopher I Murray, Jodene Eldstrom, David Fedida
The slow delayed rectifier potassium current (IKs) is a key repolarizing current during the cardiac action potential. It consists of four KCNQ1 α-subunits and up to four KCNE1 β-subunits, which are thought to reside within external clefts of the channel. The interaction of KCNE1 with KCNQ1 dramatically delays opening of the channel but the mechanisms by which this occur are not yet fully understood. Here, we have used unnatural amino acid photo-cross-linking to investigate the dynamic interactions that occur between KCNQ1 and KCNE1 during activation gating...
July 25, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28705875/electrical-and-structural-substrate-of-arrhythmogenic-right-ventricular-cardiomyopathy-determined-using-noninvasive-electrocardiographic-imaging-and-late-gadolinium-magnetic-resonance-imaging
#14
Christopher M Andrews, Neil T Srinivasan, Stefania Rosmini, Heerajnarain Bulluck, Michele Orini, Sharon Jenkins, Antonis Pantazis, William J McKenna, James C Moon, Pier D Lambiase, Yoram Rudy
BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a significant cause of sudden cardiac death in the young. Improved noninvasive assessment of ARVC and better understanding of the disease substrate are important for improving patient outcomes. METHODS AND RESULTS: We studied 20 genotyped ARVC patients with a broad spectrum of disease using electrocardiographic imaging (a method for noninvasive cardiac electrophysiology mapping) and advanced late gadolinium enhancement cardiac magnetic resonance scar imaging...
July 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28689986/quaternion-based-study-of-angular-velocity-of-the-cardiac-vector-during-myocardial-ischaemia
#15
Pablo Daniel Cruces, Pedro David Arini
BACKGROUND: Early detection of acute ischaemia through non-invasive methods remains a challenge in health research. Ischaemic condition caused by a decrease in the blood supply in a cardiac region induces hypoxia and metabolic abnormalities that contribute to the electrical instability of the heart and to the development of slow conduction in damaged tissue. METHODS: Herein, a percutaneous transluminal coronary angiography (PTCA) is considered as a model of supply ischaemia...
December 1, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28687671/tachycardia-induced-j-wave-changes-in-patients-with-and-without-idiopathic-ventricular-fibrillation
#16
Yoshiyasu Aizawa, Seiji Takatsuki, Takahiko Nishiyama, Takehiro Kimura, Shun Kohsaka, Yoshiaki Kaneko, Yasuya Inden, Naohiko Takahashi, Satoshi Nagase, Yoshifusa Aizawa, Keichi Fukuda
BACKGROUND: To know the underlying mechanisms of J waves, the response to atrial pacing was studied in patients with idiopathic ventricular fibrillation (IVF) and patients with non-IVF. METHODS AND RESULTS: In 8 patients with IVF, the J-wave amplitude was measured before, during, and after atrial pacing. All patients had episodes of ventricular fibrillation without structural heart disease. The responses of J waves were compared with those of the 17 non-IVF control subjects who revealed J waves but no history of cardiac arrest and underwent electrophysiological study...
July 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28685701/the-role-of-quinidine-in-the-pharmacological-therapy-of-ventricular-arrhythmias-quinidine
#17
Bojana Bozic, Teodora Vidonja Uzelac, Aleksandra Kezic, Milica Bajcetic
BACKGROUND: Historically, quinidine was the first medicine used in the therapy of heart arrhythmias. Studies in the early 20th century identified quinidine, a diastereomer of the antimalarial quinine, as the most potent of the antiarrhythmic substances extracted from the cinchona plant. Quinidine is used by the 1920s, as an antiarrhythmic agent to maintain sinus rhythm after conversion from atrial flutter or atrial fibrillation and to prevent recurrence of ventricular tachycardia or ventricular fibrillation...
July 7, 2017: Mini Reviews in Medicinal Chemistry
https://www.readbyqxmd.com/read/28685698/medical-therapy-for-long-qt-syndrome
#18
George Adamos, Nicoletta Iacovidou, Theodoros Xanthos
Long QT syndrome (LQTS) is an arrhythmogenic disorder characterized by repolarization abnormalities with a propensity to cause life threatening cardiac events. The first manifestation of the syndrome may be sudden death, therefore, early diagnosis and therapy is of great importance. LQTS can be both congenital and acquired. The latter is most commonly seen in hospitalized patients and such individuals have an easily recognizable and reversible precipitating factor (electrolyte disturbances, certain drugs etc...
July 7, 2017: Mini Reviews in Medicinal Chemistry
https://www.readbyqxmd.com/read/28668303/ca-2-activated-cl-current-is-antiarrhythmic-by-reducing-both-spatial-and-temporal-heterogeneity-of-cardiac-repolarization
#19
Bence Hegyi, Balázs Horváth, Krisztina Váczi, Mónika Gönczi, Kornél Kistamás, Ferenc Ruzsnavszky, Roland Veress, Leighton T Izu, Ye Chen-Izu, Tamás Bányász, János Magyar, László Csernoch, Péter P Nánási, Norbert Szentandrássy
The role of Ca(2+)-activated Cl(-) current (ICl(Ca)) in cardiac arrhythmias is still controversial. It can generate delayed afterdepolarizations in Ca(2+)-overloaded cells while in other studies incidence of early afterdepolarization (EAD) was reduced by ICl(Ca). Therefore our goal was to examine the role of ICl(Ca) in spatial and temporal heterogeneity of cardiac repolarization and EAD formation. Experiments were performed on isolated canine cardiomyocytes originating from various regions of the left ventricle; subepicardial, midmyocardial and subendocardial cells, as well as apical and basal cells of the midmyocardium...
August 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/28659867/increased-short-term-beat-to-beat-qt-interval-variability-in-patients-with-impaired-glucose-tolerance
#20
Andrea Orosz, István Baczkó, Szabolcs Nyiraty, Anna E Körei, Zsuzsanna Putz, Róbert Takács, Attila Nemes, Tamás T Várkonyi, László Balogh, György Ábrahám, Péter Kempler, Julius Gy Papp, András Varró, Csaba Lengyel
Prediabetic states and diabetes are important risk factors for cardiovascular morbidity and mortality. Determination of short-term QT interval variability (STVQT) is a non-invasive method for assessment of proarrhythmic risk. The aim of the study was to evaluate the STVQT in patients with impaired glucose tolerance (IGT). 18 IGT patients [age: 63 ± 11 years, body mass index (BMI): 31 ± 6 kg/m(2), fasting glucose: 6.0 ± 0.4 mmol/l, 120 min postload glucose: 9.0 ± 1.0 mmol/l, hemoglobin A1c (HbA1c): 5...
2017: Frontiers in Endocrinology
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