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Early repolarization

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https://www.readbyqxmd.com/read/29784488/j-wave-syndromes-electrocardiographic-and-clinical-aspects
#1
REVIEW
Silvia G Priori, Carlo Napolitano
Early repolarization, Brugada syndrome, and pathologic J waves have been described for decades, but only recently experimental and clinical data have allowed reconciliation of Brugada and Early Repolarization under the common definition of J-wave syndromes. The concept was derived from studies showing, in both conditions, the presence of transmural dispersion of repolarization, localized conduction abnormalities, and abnormal transition between QRS and ST segment on electrocardiogram. Although several clinical studies have addressed the clinical presentation and epidemiology of J-wave syndromes, relevant knowledge gaps exist...
June 2018: Cardiac Electrophysiology Clinics
https://www.readbyqxmd.com/read/29771311/pathobiology-of-cardiac-dyssynchrony-and-resynchronization-therapy
#2
Uyên Châu Nguyên, Nienke J Verzaal, Frans A van Nieuwenhoven, Kevin Vernooy, Frits W Prinzen
Synchronous ventricular electrical activation is a prerequisite for adequate left ventricular (LV) systolic function. Conduction abnormalities such as left bundle branch block, and ventricular pacing lead to a dyssynchronous electrical activation sequence, which may have deleterious consequences. The present review attempts to connect the various processes involved in the development of 'dyssynchronopathy', and its correction by cardiac resynchronization therapy (CRT). Abnormal electrical impulse conduction leads to abnormal contraction, characterized by regional differences in timing as well as shortening patterns and amount of external work performed...
May 15, 2018: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/29769222/transient-outward-k-current-i-to-underlies-the-right-ventricular-initiation-of-polymorphic-ventricular-tachycardia-in-a-transgenic-rabbit-model-of-long-qt-syndrome-type-1
#3
Bum-Rak Choi, Weiyan Li, Dmitry Terentyev, Anatoli Y Kabakov, Mingwang Zhong, Colin M Rees, Radmila Terentyeva, Tae Yun Kim, Zhilin Qu, Xuwen Peng, Alain Karma, Gideon Koren
BACKGROUND: Sudden death in long-QT syndrome type 1 (LQT1), an inherited disease caused by loss-of-function mutations in KCNQ1, is triggered by early afterdepolarizations (EADs) that initiate polymorphic ventricular tachycardia (pVT). We investigated ionic mechanisms that underlie pVT in LQT1 using a transgenic rabbit model of LQT1. METHODS: Optical mapping, cellular patch clamping, and computer modeling were used to elucidate the mechanisms of EADs in transgenic LQT1 rabbits...
June 2018: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29759629/circadian-variation-of-ventricular-arrhythmias-in-catecholaminergic-polymorphic-ventricular-tachycardia
#4
Christina Y Miyake, S Yukiko Asaki, Gregory Webster, Richard J Czosek, Joseph Atallah, Kishor Avasarala, Sri O Rao, Patricia E Thomas, Jeffrey J Kim, Santiago O Valdes, Caridad de la Uz, Yunfei Wang, Xander H T Wehrens, Dominic Abrams
OBJECTIVES: The aim of this paper was to investigate whether ventricular arrhythmias in children with catecholaminergic polymorphic ventricular tachycardia (CPVT) show circadian patterns. BACKGROUND: Circadian arrhythmic patterns have been established in long QT, Brugada, and early repolarization, but have not been investigated in CPVT. METHODS: This is a multicenter, retrospective review of pediatric CPVT patients, age <21 years at diagnosis...
November 2017: JACC. Clinical Electrophysiology
https://www.readbyqxmd.com/read/29758700/memory-induced-nonlinear-dynamics-of-excitation-in-cardiac-diseases
#5
Julian Landaw, Zhilin Qu
Excitable cells, such as cardiac myocytes, exhibit short-term memory, i.e., the state of the cell depends on its history of excitation. Memory can originate from slow recovery of membrane ion channels or from accumulation of intracellular ion concentrations, such as calcium ion or sodium ion concentration accumulation. Here we examine the effects of memory on excitation dynamics in cardiac myocytes under two diseased conditions, early repolarization and reduced repolarization reserve, each with memory from two different sources: slow recovery of a potassium ion channel and slow accumulation of the intracellular calcium ion concentration...
April 2018: Physical Review. E
https://www.readbyqxmd.com/read/29745804/protection-against-severe-hypokalemia-but-impaired-cardiac-repolarization-after-intense-rowing-exercise-in-healthy-humans-receiving-salbutamol
#6
Tania Atanasovska, Robert Smith, Claus Graff, Cao Thach Tran, Jacob Melgaard, Jørgen K Kanters, Aaron C Petersen, Antony Tobin, Keld P Kjeldsen, Michael John McKenna
Intense exercise induces pronounced hyperkalemia, followed by transient hypokalemia in recovery. We investigated whether the β2 -agonist salbutamol attenuated the exercise-hyperkalemia, and exacerbated the post-exercise hypokalemia, and whether hypokalemia was associated with impaired cardiac repolarization (QT hysteresis). Eleven healthy adults participated in a randomized, counterbalanced, double-blind trial receiving either 1000 µg salbutamol (SAL) or placebo (PLAC) by inhalation. Arterial plasma potassium concentration ([K+ ]a ) was measured at rest, during 3 min intense rowing exercise and 60 min recovery...
May 10, 2018: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29731285/prehospital-acute-st-elevation-myocardial-infarction-identification-in-san-diego-a-retrospective-analysis-of-the-effect-of-a-new-software-algorithm
#7
Christanne Coffey, John Serra, Mat Goebel, Sarah Espinoza, Edward Castillo, James Dunford
BACKGROUND: A significant increase in false positive ST-elevation myocardial infarction (STEMI) electrocardiogram interpretations was noted after replacement of all of the City of San Diego's 110 monitor-defibrillator units with a new brand. These concerns were brought to the manufacturer and a revised interpretive algorithm was implemented. OBJECTIVES: This study evaluated the effects of a revised interpretation algorithm to identify STEMI when used by San Diego paramedics...
May 3, 2018: Journal of Emergency Medicine
https://www.readbyqxmd.com/read/29704608/comparison-of-one-and-three-lead-ecg-to-measure-cardiac-intervals-and-differentiate-drug-induced-multi-channel-block
#8
Robert Brockway, Marina Brockway, Brian Brockway, Robert Hamlin
INTRODUCTION: FDA has established initiatives to characterize clinical and non-clinical biomarkers to enable more precise prediction of proarrhythmia risk based upon knowledge of drug effect on multiple cardiac ion channels (Colatsky et al., 2016). The FDA has recently demonstrated superiority of early ventricular repolarization interval (JTp) in differentiating pure hERG block from multi-channel block in human subjects. Preclinical studies often acquire a single lead ECG, whereas FDA measurements of JTp were derived ​from a spatial vectorcardiogram computed using multiple leads...
April 25, 2018: Journal of Pharmacological and Toxicological Methods
https://www.readbyqxmd.com/read/29686626/modeling-the-electrophysiological-properties-of-the-infarct-border-zone
#9
REVIEW
Caroline Mendonca Costa, Gernot Plank, Christopher A Rinaldi, Steven A Niederer, Martin J Bishop
Ventricular arrhythmias (VA) in patients with myocardial infarction (MI) are thought to be associated with structural and electrophysiological remodeling within the infarct border zone (BZ). Personalized computational models have been used to investigate the potential role of the infarct BZ in arrhythmogenesis, which still remains incompletely understood. Most recent models have relied on experimental data to assign BZ properties. However, experimental measurements vary significantly resulting in different computational representations of this region...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29667218/early-repolarization-is-involved-in-ventricular-fibrillation-in-patients-with-variant-angina
#10
Tetsuji Shinohara, Hidekazu Kondo, Akira Fukui, Hidefumi Akioka, Yasushi Teshima, Kunio Yufu, Mikiko Nakagawa, Naohiko Takahashi
BACKGROUND: Variant angina (VA) is caused by reversible coronary artery spasm, which is characterized by chest pain with ST segment elevations on a standard 12-lead electrocardiogram (ECG) at rest. VA attack often causes lethal ventricular arrhythmia. The early repolarization (ER) pattern is associated with ventricular fibrillation (VF). However, whether the ER pattern is involved in VF in patients with VA is not known. We investigated the association between the ER pattern and VF in patients with VA...
April 17, 2018: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/29666184/atp-sensitive-potassium-channels-in-the-sinoatrial-node-contribute-to-heart-rate-control-and-adaptation-to-hypoxia
#11
Qadeer Aziz, Malcolm Finlay, David Montaigne, Leona Ojake, Yiwen Li, Naomi Anderson, Andreas Ludwig, Andrew Tinker
ATP-sensitive potassium channels (KATP ) contribute to membrane currents in many tissues, are responsive to intracellular metabolism, and open as ATP falls and ADP rises. KATP channels are widely distributed in tissues and are prominently expressed in the heart. They have generally been observed in ventricular tissue, but they are also expressed in the atria and conduction tissues. In this study, we focused on the contribution and role of the inwardly rectifying KATP channel subunit, Kir6.1, in the sinoatrial node (SAN)...
April 17, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29627768/mitochondrial-ca-2-influx-contributes-to-arrhythmic-risk-in-nonischemic-cardiomyopathy
#12
An Xie, Zhen Song, Hong Liu, Anyu Zhou, Guangbin Shi, Qiongying Wang, Lianzhi Gu, Man Liu, Lai-Hua Xie, Zhilin Qu, Samuel C Dudley
BACKGROUND: Heart failure (HF) is associated with increased arrhythmia risk and triggered activity. Abnormal Ca2+ handling is thought to underlie triggered activity, and mitochondria participate in Ca2+ homeostasis. METHODS AND RESULTS: A model of nonischemic HF was induced in C57BL/6 mice by hypertension. Computer simulations were performed using a mouse ventricular myocyte model of HF. Isoproterenol-induced premature ventricular contractions and ventricular fibrillation were more prevalent in nonischemic HF mice than sham controls...
April 7, 2018: Journal of the American Heart Association
https://www.readbyqxmd.com/read/29611430/diagnostic-accuracy-of-the-electrocardiographic-decision-support-myocardial-ischaemia-eds-mi-algorithm-in-detection-of-acute-coronary-occlusion
#13
Thomas Lindow, Olle Pahlm, Charles W Olson, Ardavan Khoshnood, Ulf Ekelund, Marcus Carlsson, Cees A Swenne, Sumche Man, Henrik Engblom
Electrocardiographic Decision Support - Myocardial Ischaemia (EDS-MI) is a graphical decision support for detection and localization of acute transmural ischaemia. A recent study indicated that EDS-MI performs well for detection of acute transmural ischaemia. However, its performance has not been tested in patients with non-ischaemic ST-deviation. We aimed to optimize the diagnostic accuracy of EDS-MI in patients with verified acute coronary occlusion as well as patients with non-ischaemic ST deviation and compare its performance with STEMI criteria...
April 1, 2018: European Heart Journal. Acute Cardiovascular Care
https://www.readbyqxmd.com/read/29582428/selective-late-sodium-current-inhibitor-gs-458967-suppresses-torsades-de-pointes-by-mostly-affecting-perpetuation-but-not-initiation-of-the-arrhythmia
#14
Alexandre Bossu, Marien J C Houtman, Veronique M F Meijborg, Rosanne Varkevisser, Henriette D M Beekman, Albert Dunnink, Jacques M T de Bakker, Nevena Mollova, Sridharan Rajamani, Luiz Belardinelli, Marcel A G van der Heyden, Marc A Vos
BACKGROUND AND PURPOSE: Enhanced late sodium current (late INa ) in heart failure and long QT syndrome type 3 is proarrhythmic. GS-458967 (GS967) is a selective and potent late INa inhibitor. This study aimed to evaluate the antiarrhythmic effect of late INa inhibition by GS967 in the chronic atrioventricular block (CAVB) dog model sensitive to Torsade de Pointes arrhythmias (TdP) and to elucidate its electrophysiological mode of action in vivo and in vitro. METHODS - RESULTS: GS967 (IC50 for late INa ~ 200 nM) markedly shortened action potential duration of canine ventricular cardiomyocytes and repolarization parameters in vivo in sinus rhythm (SR, n=10) dogs, in a concentration-dependent manner...
March 27, 2018: British Journal of Pharmacology
https://www.readbyqxmd.com/read/29568937/genetic-analysis-of-sick-sinus-syndrome-in-a-family-harboring-compound-cacna1c-and-ttn-mutations
#15
Yao-Bin Zhu, Jie-Wei Luo, Fen Jiang, Gui Liu
Sick sinus syndrome (SSS) is a sinus node dysfunction characterized by severe sinus bradycardia. SSS results in insufficient blood supply to the brain, heart, kidneys, and other organs and is associated with the increased risk of sudden cardiac death. Bradyarrhythmia appears in the absence of any associated cardiac pathology and displays a genetic legacy. The present study identified a family with primary manifestation of sinus bradycardia (five individuals) along with early repolarization (four individuals) and atrial fibrillation (one individual)...
March 16, 2018: Molecular Medicine Reports
https://www.readbyqxmd.com/read/29505101/evaluating-potential-qt-effects-of-jnj-54861911-a-bace-inhibitor-in-single-and-multiple-ascending-dose-studies-and-a-thorough-qt-trial-with-additional-retrospective-confirmation-using-concentration-qtc-analysis
#16
Maarten Timmers, Vikash Sinha, Borje Darpo, Brian Smith, Randy Brown, Hongqi Xue, Georg Ferber, Johannes Streffer, Alberto Russu, Luc Tritsmans, Bhavna Solanki, Jennifer Bogert, Luc Van Nueten, Giacomo Salvadore, Partha Nandy
Nonclinical assays with JNJ-54861911, a β-secretase 1 inhibitor have indicated that at high concentrations, it may delay cardiac repolarization. A 4-way crossover thorough QT (TQT) study was performed in 64 healthy subjects with 50 and 150 mg JNJ-54861911 once daily for 7 days, placebo, and 400 mg moxifloxacin. Retrospective high-precision QT (HPQT) analysis was performed on serial elecrocardiograms extracted from first-in-human single-ascending dose (SAD) and multiple-ascending dose (MAD) studies to evaluate if early studies could detect and predict QT effect...
March 5, 2018: Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/29502127/detection-of-acute-myocardial-infarction-in-a-pig-model-using-the-san-atrial-avn-his-saah-electrocardiogram-ecg-model-phs-a10-an-automated-and-integrated-signals-recognition-system
#17
Wenjiao Zhao, Guihua Lu, Li Liu, Zhishan Sun, Mingxin Wu, Wenyan Yi, Haiyan Chen, Yanhui Li, Lilong Tang, Jianping Zeng
BACKGROUND The aim of this study was to compare the use of the standard 12-lead electrocardiogram (ECG) with the SAN-Atrial-AVN-His (SAAH) ECG (Model PHS-A10), a new automated and integrated signals recognition system that detects micro-waveforms within the P, QRS, and T-wave, in a pig model of acute myocardial infarction (MI). MATERIAL AND METHODS Six medium-sized domestic Chinese pigs underwent general anesthesia, and an angioplasty balloon was placed and dilated for 120 minutes in the first diagonal coronary artery arising from the left anterior descending (LAD) coronary artery...
March 4, 2018: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
https://www.readbyqxmd.com/read/29460660/early-repolarization-pattern-in-the-coronary-slow-flow-phenomenon
#18
Murat Sucu, Berzal Ucaman, Gökhan Altunbas
BACKGROUND: The coronary slow flow phenomenon (CSFP) is well-documented, and the early repolarization pattern (ERP) has recently been shown to be a risk factor for the development of malignant ventricular arrhythmias. METHODS: Those with true CSFP were included as cases and those with normal angiograms were included as controls. We assessed J-point elevation on surface electrocardiograms (ECGs) and defined ERP as notching or slurring of the terminal portion of the QRS takeoff...
February 20, 2018: Scandinavian Cardiovascular Journal: SCJ
https://www.readbyqxmd.com/read/29436392/significance-of-coronary-artery-spasm-diagnosis-in-patients-with-early-repolarization-syndrome
#19
Tsukasa Kamakura, Mitsuru Wada, Kohei Ishibashi, Yuko Y Inoue, Koji Miyamoto, Hideo Okamura, Satoshi Nagase, Takashi Noda, Takeshi Aiba, Satoshi Yasuda, Wataru Shimizu, Shiro Kamakura, Kengo Kusano
BACKGROUND: Previously described patients with early repolarization syndrome (ERS) may have experienced silent coronary artery spasm (CAS) because the diagnosis of CAS was mainly based on symptoms or coronary angiography findings, without performing a spasm provocation test. This study investigated the significance of CAS diagnosis and evaluated the incidence of silent CAS in patients with possible ERS (ie, idiopathic ventricular fibrillation [VF] and inferolateral J wave). METHODS AND RESULTS: The study included 34 patients with idiopathic VF and inferolateral J wave...
February 7, 2018: Journal of the American Heart Association
https://www.readbyqxmd.com/read/29407007/new-insights-into-the-use-of-the-12-lead-electrocardiogram-for-diagnosing-acute-myocardial-infarction-in-the-emergency-department
#20
REVIEW
David F Miranda, Angie S Lobo, Brooks Walsh, Yader Sandoval, Stephen W Smith
The 12-lead electrocardiogram (ECG) remains the most immediately accessible and widely used initial diagnostic tool for guiding management in patients with suspected myocardial infarction (MI). Although the development of high-sensitivity cardiac troponin assays has improved the rule-in and rule-out and risk stratification of acute MI without ST elevation, the immediate management of the subset of acute MI with acute coronary occlusion depends on integrating clinical presentation and ECG findings. Careful interpretation of the ECG might yield subtle features suggestive of ischemia that might facilitate more rapid triage of patients with subtle acute coronary occlusion or, conversely, in identification of ST-elevation MI mimics (pseudo ST-elevation MI patterns)...
February 2018: Canadian Journal of Cardiology
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