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Ventricular depolarization

Abdunoor M Kabanywanyi, Rita Baiden, Ali M Ali, Muhidin K Mahende, Bernhards R Ogutu, Abraham Oduro, Halidou Tinto, Margaret Gyapong, Ali Sie, Esperanca Sevene, Eusebio Macete, Seth Owusu-Agyei, Alex Adjei, Guillaume Compaoré, Innocent Valea, Isaac Osei, Abena Yawson, Martin Adjuik, Raymond Akparibo, Mwaka A Kakolwa, Salim Abdulla, Fred Binka
The antimalarial drug piperaquine is associated with delayed ventricular depolarization, causing prolonged QT interval (time taken for ventricular de-polarisation and re-polarisation). There is a lack of safety data regarding dihydroartemisinin/piperaquine (DHA/PPQ) for the treatment of uncomplicated malaria, which has limited its use. We created a platform where electrocardiograms (ECG) were performed in public hospitals for the safety assessment of DHA/PPQ, at baseline before the use of dihydroartemisinin/piperaquine (Eurartesim®), and on day 3 (before and after administration of the final dose) and day 7 post-administration...
2016: PloS One
Hao Xu, Manxi Zhao, Shenghui Liang, Quanshu Huang, Yunchuan Xiao, Liang Ye, Qinyi Wang, Longmei He, Lanxiang Ma, Hua Zhang, Li Zhang, Hui Jiang, Xiao Ke, Yuchun Gu
Puerarin, a known isoflavone, is commonly found as a Chinese herb medicine. It is widely used in China to treat cardiac diseases such as angina, cardiac infarction and arrhythmia. However, its cardioprotective mechanism remains unclear. In this study, puerarin significantly prolonged ventricular action potential duration (APD) with a dosage dependent manner in the micromolar range on isolated rat ventricular myocytes. However, submicromolar puerarin had no effect on resting membrane potential (RMP), action potential amplitude (APA) and maximal velocity of depolarization (Vmax) of action potential...
October 20, 2016: Scientific Reports
Naokata Sumitomo
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is induced by emotions or exercise in patients without organic heart disease and may be polymorphic or bidirectional in nature. The prognosis of CPVT is not good, and therefore prevention of sudden death is of utmost importance. Genetic variants of CPVT include RyR2, CASQ2, CALM2, TRD, and possibly KCNJ2 and ANK2 gene mutations. Hypotheses that suggest the causes of CPVT include weakened binding of FKBP12.6 and RyR2, a store overload-induced Ca(2+) release (SOICR), unzipping of intramolecular domain interactions in RyR2, and molecular and functional abnormalities caused by mutations in the CASQ2 gene...
October 2016: Journal of Arrhythmia
Satoshi Umemura
Primary aldosteronism (PA) is a heterogeneous group of disorders including both sporadic and familial forms (familial hyperaldosteronism type I, II and III). PA is the most frequent endocrine cause of secondary hypertension and associated with a higher rate of cardiovascular complications, compared with essential hypertension.Here I review the recent progress in understanding of the genetic and molecular mechanisms leading to autonomous aldosterone production in PA.Systematic screening detects primary aldosteronism in 5 to 10% of all patients with hypertension and in approximately 20% of patients with resistant hypertension...
September 2016: Journal of Hypertension
Onur Kaypakli, Mevlüt Koç, Gökhan Gözübüyük, Durmuş Yıldıray Şahin
AIM: CRT was shown to improve HF prognosis. But many patients do not benefit from CRT. Optimization of LV lead position to the latest activated LV area is important to increase CRT response. We aimed to detect the relationship between LV lead sensing delay and echocardiographic and electrocardiographic response to CRT treatment. METHODS: We prospectively included 156 consecutive patients with HF diagnosis, QRS≥120 ms, LBBB, NYHA II-IV, LVEF<35% and scheduled for CRT (100 male, 56 female; mean age 65...
October 18, 2016: Pacing and Clinical Electrophysiology: PACE
Shingo Maeda, William W Chik, Jackson J Liang, Iosif Kelesidis, Ruben Casado Arroyo, Benjamin D'Souza, Mouhannad M Sadek, Daniele Muser, Fabien Squara, Deviprasad Venugopal, Pasquale Santangeli, David S Frankel, Erica S Zado, Francis E Marchlinski, David J Callans
PURPOSE: Frequent ventricular premature depolarizations (VPDs) may cause cardiomyopathy (VPDCM), which often improves after VPD suppression. This study aimed to evaluate whether ablation of outflow tract ventricular arrhythmias (OT VAs) in patients with VPDCM improves renal in addition to left ventricular (LV) function. METHODS: We retrospectively evaluated 153 patients with OT VAs and examined VPD burden and LV ejection fraction (LVEF), as well as estimated glomerular filtration rate (eGFR) pre- and post-ablation...
October 10, 2016: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
Hui Yang, Fabio Leonelli
QRS morphology is commonly used in the electrocardiographic diagnosis of ventricular depolarization such as left bundle branch block (LBBB) and ventricular septal infarction. We investigated whether pattern matching of QRS loops in the 3-dimensional vectorcardiogram (VCG) will improve the grouping of patients whose space-time electrical activity akin to each other, thereby assisting in clinical decision making. First, pattern dissimilarity of VCG QRS loops is qualitatively measured and characterized among patients, resulting in a 93×93 distance matrix of patient-to-patient dissimilarity...
September 28, 2016: Computers in Biology and Medicine
Felix Hohendanner, Jaime DeSantiago, Frank R Heinzel, Lothar A Blatter
We tested the hypothesis that in atrial myocytes from a rabbit left ventricular heart failure (HF) model, spatial inhomogeneity and temporal dyssynchrony of Ca removal during excitation-contraction coupling together with increased Na/Ca exchange (NCX) activity generates a substrate for proarrhythmic Ca release. Ca removal occurs via Ca reuptake into the sarcoplasmic reticulum and extrusion via NCX exclusively in the cell periphery since rabbit atrial myocytes lack transverse tubules. Ca removal kinetics were assessed by the time constant τ of decay of local peripheral subsarcolemmal (SS) and central (CT) action potential (AP) induced Ca transients (CaTs) recorded in confocal line scan mode (using Fluo-4)...
September 30, 2016: American Journal of Physiology. Heart and Circulatory Physiology
Satoshi Umemura
Primary aldosteronism (PA) is a heterogeneous group of disorders including both sporadic and familial forms (familial hyperaldosteronism type I, II and III). PA is the most frequent endocrine cause of secondary hypertension and associated with a higher rate of cardiovascular complications, compared with essential hypertension.Here I review the recent progress in understanding of the genetic and molecular mechanisms leading to autonomous aldosterone production in PA.Systematic screening detects primary aldosteronism in 5 to 10% of all patients with hypertension and in approximately 20% of patients with resistant hypertension...
September 2016: Journal of Hypertension
Juan Sieira, Gregory Dendramis, Pedro Brugada
Brugada syndrome is an inherited disease characterized by an increased risk of sudden cardiac death owing to ventricular arrhythmias in the absence of structural heart disease. Since the first description of the syndrome >20 years ago, considerable advances have been made in our understanding of the underlying mechanisms involved and the strategies to stratify at-risk patients. The development of repolarization-depolarization abnormalities in patients with Brugada syndrome can involve genetic alterations, abnormal neural crest cell migration, improper gap junctional communication, or connexome abnormalities...
September 15, 2016: Nature Reviews. Cardiology
Tobias Bruegmann, Patrick M Boyle, Christoph C Vogt, Thomas V Karathanos, Hermenegild J Arevalo, Bernd K Fleischmann, Natalia A Trayanova, Philipp Sasse
Ventricular arrhythmias are among the most severe complications of heart disease and can result in sudden cardiac death. Patients at risk currently receive implantable defibrillators that deliver electrical shocks to terminate arrhythmias on demand. However, strong electrical shocks can damage the heart and cause severe pain. Therefore, we have tested optogenetic defibrillation using expression of the light-sensitive channel channelrhodopsin-2 (ChR2) in cardiac tissue. Epicardial illumination effectively terminated ventricular arrhythmias in hearts from transgenic mice and from WT mice after adeno-associated virus-based gene transfer of ChR2...
October 3, 2016: Journal of Clinical Investigation
Veronique M F Meijborg, Mark Potse, Chantal E Conrath, Charly N W Belterman, Jacques M T De Bakker, Ruben Coronel
BACKGROUND: J-waves in inferolateral leads are associated with a higher risk for idiopathic ventricular fibrillation. We aimed to test potential mechanisms (depolarization or repolarization dependent) responsible for inferolateral J-waves. We hypothesized that inferolateral J-waves can be caused by regional delayed activation of myocardium that is activated late during normal conditions. METHODS: Computer simulations were performed to evaluate how J-point elevation is influenced by reducing sodium current conductivity (GNa), increasing transient outward current conductivity (Gto), or cellular uncoupling in three predefined ventricular regions (lateral, anterior, or septal)...
2016: Frontiers in Physiology
Lara Testai, Alice Marino, Ilaria Piano, Vincenzo Brancaleone, Kengo Tomita, Lorenzo Di Cesare Mannelli, Alma Martelli, Valentina Citi, Maria C Breschi, Roberto Levi, Claudia Gargini, Mariarosaria Bucci, Giuseppe Cirino, Carla Ghelardini, Vincenzo Calderone
The endogenous gasotransmitter hydrogen sulphide (H2S) is an important regulator of the cardiovascular system, particularly of myocardial function. Moreover, H2S exhibits cardioprotective activity against ischemia/reperfusion (I/R) or hypoxic injury, and is considered an important mediator of "ischemic preconditioning", through activation of mitochondrial potassium channels, reduction of oxidative stress, activation of the endogenous "anti-oxidant machinery" and limitation of inflammatory responses. Accordingly, H2S-donors, i...
September 9, 2016: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
M A Oyama, M J Hezzell, D S Laughlin, C L Thorn, M S Kraus, A R Gelzer
Management of symptomatic bradyarrhythmias such as complete atrioventricular block often involves permanent implantation of a transvenous pacemaker. Both during and after implantation, the operator can telemetrically assess and adjust a variety of electrical parameters associated with the pacemaker function in order to optimize the sensitivity, reliability, and power consumption of the device. Herein, we report an unexpected change in the paced electrocardiographic QRS complex morphology in two dogs undergoing bipolar pacing associated with changes in the pacemaker output amplitude settings first detected during threshold testing...
September 6, 2016: Journal of Veterinary Cardiology: the Official Journal of the European Society of Veterinary Cardiology
Daniel S Evans, Christy L Avery, Mike A Nalls, Guo Li, John Barnard, Erin N Smith, Toshiko Tanaka, Anne M Butler, Sarah G Buxbaum, Alvaro Alonso, Dan E Arking, Gerald S Berenson, Joshua C Bis, Steven Buyske, Cara L Carty, Wei Chen, Mina K Chung, Steven R Cummings, Rajat Deo, Charles B Eaton, Ervin R Fox, Susan R Heckbert, Gerardo Heiss, Lucia A Hindorff, Wen-Chi Hsueh, Aaron Isaacs, Yalda Jamshidi, Kathleen F Kerr, Felix Liu, Yongmei Liu, Kurt K Lohman, Jared W Magnani, Joseph F Maher, Reena Mehra, Yan A Meng, Solomon K Musani, Christopher Newton-Cheh, Kari E North, Bruce M Psaty, Susan Redline, Jerome I Rotter, Renate B Schnabel, Nicholas J Schork, Ralph V Shohet, Andrew B Singleton, Jonathan D Smith, Elsayed Z Soliman, Sathanur R Srinivasan, Herman A Taylor, David R Van Wagoner, James G Wilson, Taylor Young, Zhu-Ming Zhang, Alan B Zonderman, Michele K Evans, Luigi Ferrucci, Sarah S Murray, Gregory J Tranah, Eric A Whitsel, Alex P Reiner, Nona Sotoodehnia
The electrocardiographic QRS duration, a measure of ventricular depolarization and conduction, is associated with cardiovascular mortality. While genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) associated with QRS duration at 22 loci among those of European descent, the genetic architecture of QRS duration in non-European populations is largely unknown. We therefore performed a GWAS meta-analysis of QRS duration in 13,031 African Americans from ten cohorts and a transethnic GWAS meta-analysis with additional results from populations of European descent...
August 29, 2016: Human Molecular Genetics
Chao Wang, Lei-Lei Wang, Chi Zhang, Zhen-Zhen Cao, An-Tao Luo, Pei-Hua Zhang, Xin-Rong Fan, Ji-Hua Ma
AIM: The augmentation of late sodium current (INa.L) not only causes intracellular Na(+) accumulation, which results in intracellular Ca(2+) overload via the reverse mode of the Na(+)/Ca(2+) exchange current (reverse-INCX), but also prolongs APD and induces early afterdepolarizations (EAD), which can lead to arrhythmia and cardiac dysfunction. Thus, the inhibition of INa.L is considered to be a potential way for therapeutic intervention in ischemia and heart failure. In this study we investigated the effects of tolterodine (Tol), a competitive muscarinic receptor antagonist, on normal and veratridine (Ver)-augmented INa...
August 29, 2016: Acta Pharmacologica Sinica
Giulio Conte, Carlo de Asmundis, Juan Sieira, Giuseppe Ciconte, Giacomo Di Giovanni, Gian-Battista Chierchia, Ruben Casado-Arroyo, Giannis Baltogiannis, Erwin Ströker, Ghazala Irfan, Gudrun Pappaert, Angelo Auricchio, Pedro Brugada
BACKGROUND: The phenotypic heterogeneity of Brugada syndrome (BrS) can lead some patients to show an additional inferolateral early repolarization pattern (ERP), or fragmented QRS (f-QRS). The aim of the study was to investigate the prevalence and clinical impact of f-QRS, ERP or combined f-QRS/ERP in high-risk patients with BrS. METHODS AND RESULTS: Patients with spontaneous or drug-induced BrS and an indication to receive an implantable cardioverter-defibrillator (ICD) were considered eligible for this study...
September 23, 2016: Circulation Journal: Official Journal of the Japanese Circulation Society
Hidetoshi Uchida, Miki Nishio, Yumi Omeki, Yuka Takeuchi, Rina Nagata, Shota Oikawa, Arisa Nagatani, Yoshihiko Eryu, Tadayoshi Hata, Tetsushi Yoshikawa
: In patients with a ventricular septal defect, left-to-right shunting increases the left ventricular preload. This pathological change affects myocardial depolarization and repolarization and has the potential to evoke arrhythmogenic substrates. We examined the effect of ventricular septal defects on myocardial repolarization by investigating the variability in the repolarization interval. This retrospective study included 19 patients (mean age, 1.8 ± 2.1 years) who underwent surgical closure (mean left-to-right shunt ratio, 2...
August 23, 2016: Pediatric Cardiology
Christos-Konstantinos Antoniou, Ippokratis Bournellis, Achilleas Papadopoulos, Dimitris Tsiachris, Petros Arsenos, Polychronis Dilaveris, Ioannis Diakogiannis, Skevos Sideris, Ioannis Kallikazaros, Konstantinos A Gatzoulis, Dimitrios Tousoulis
BACKGROUND: Sudden cardiac death (SCD) occurs three times more often in psychiatric patients than in the general population. QRS fragmentation (QRSfr) and signal-averaged electrocardiography (SAECG) are simple, inexpensive, readily available tools for detecting the presence of abnormal depolarization and late potentials (LPs) in these patients, a result of either the underlying disease or treatment. METHODS: Frequency of LP detection by SAECG and QRSfr was studied in 52 psychiatric patients and compared with 30 healthy (without known structural heart disease or occurrence of ventricular arrhythmia) controls...
November 1, 2016: International Journal of Cardiology
Z Horakova, P Matejovic, M Pasek, J Hosek, M Simurdova, J Simurda, M Bebarova
Atrial fibrillation is the most common arrhythmia at alcohol consumption. Its pathogenesis is complex, at least partly related to changes of cardiac inward rectifier potassium currents including IK1. Both ethanol and acetaldehyde have been demonstrated to considerably modify IK1 in rat ventricular myocytes. However, analogical data on the atrial IK1 are lacking. The present study aimed to analyse IK1 changes induced by ethanol and acetyldehyde in atrial myocytes. The experiments were performed by the whole cell patch-clamp technique at 23 ± 1°C on enzymatically isolated rat and guinea-pig atrial myocytes as well as on expressed human Kir2...
June 2016: Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society
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