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Prolonged QT syndrome

Valentina Kutyifa, Usama Daimee, Scott McNitt, Bronislava Polonsky, Charles Lowenstein, Kris Cutter, Coeli Lopes, Wojciech Zareba, Arthur J Moss
BACKGROUND: A comprehensive report on the clinical course of the three major genotypes of the long QT syndrome (LQTS) in a large U.S. patient cohort is lacking. METHODS: Our study consisted of 1,923 U.S. subjects from the Rochester-based LQTS Registry with genotype-positive LQT1 (n = 879), LQT2 (n = 807), and LQT3 (n = 237). We evaluated the risk of a first cardiac event (syncope, aborted cardiac arrest, or sudden cardiac death, whichever occurred first) from birth through age 50 years...
March 5, 2018: Annals of Noninvasive Electrocardiology
Cecilia Villa Etchegoyen, Guillermo Alberto Keller, Sebastian Mrad, Sixuan Cheng, Guillermo DiGirolamo
Drug-induced QT interval prolongation is the most frequent cause of Long QT syndrome (LQTS) in the clinical practice. This electrophysiological entity, produced by an extended duration of the myocardial repolarization and reflected as a prolonged QT interval in the superficial electrocardiogram (EKG), increases the risk of polymorphic ventricular tachycardia (Torsades de Pointes) appearance and sudden death. Certain antiarrhythmic drugs such as amiodarone, sotalol, quinidine, procainamide, verapamil and diltiazem are known as drugs that, due to their mechanism of action, prolong the QT interval, demanding constant monitorization...
February 23, 2018: Current Clinical Pharmacology
J R Giudicessi, M J Ackerman, M Camilleri
BACKGROUND: Gastrointestinal sensorimotor dysfunction underlies a wide range of esophageal, gastric, and intestinal motility and functional disorders that collectively constitute nearly half of all referrals to gastroenterologists. As a result, substantial effort has been dedicated toward the development of prokinetic agents intended to augment or restore normal gastrointestinal motility. However, the use of several clinically efficacious gastroprokinetic agents, such as cisapride, domperidone, erythromycin, and tegaserod, is associated with unfavorable cardiovascular safety profiles, leading to restrictions in their use...
February 14, 2018: Neurogastroenterology and Motility: the Official Journal of the European Gastrointestinal Motility Society
Sam Chai, Xiaoping Wan, Angelina Ramirez-Navarro, Paul J Tesar, Elizabeth S Kaufman, Eckhard Ficker, Alfred L George, Isabelle Deschênes
Congenital long QT syndrome (LQTS) is an inherited channelopathy associated with life-threatening arrhythmias. LQTS type 2 (LQT2) is caused by mutations in KCNH2, which encodes the potassium channel hERG. We hypothesized that modifier genes are partly responsible for the variable phenotype severity observed in some LQT2 families. Here, we identified contributors to variable expressivity in an LQT2 family by using induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and whole exome sequencing in a synergistic manner...
February 12, 2018: Journal of Clinical Investigation
John R Giudicessi, Dan M Roden, Arthur A M Wilde, Michael J Ackerman
The acquired and congenital forms of long QT syndrome represent 2 distinct but clinically and genetically intertwined disorders of cardiac repolarization characterized by the shared final common pathway of QT interval prolongation and risk of potentially life-threatening arrhythmias. Over the past 2 decades, our understanding of the spectrum of genetic variation that (1) perturbs the function of cardiac ion channel macromolecular complexes and intracellular calcium-handling proteins, (2) underlies acquired/congenital long QT syndrome susceptibility, and (3) serves as a determinant of QT interval duration in the general population has grown exponentially...
February 6, 2018: Circulation
Andy Forbes, Mary Hobart, John Ouyang, Lily Shi, Stephanie Pfister, Mika Hakala
Background: Brexpiprazole is a serotonin-dopamine activity modulator with efficacy in acute schizophrenia and relapse prevention. The aim of this Phase 3, multicenter study was to assess the long-term safety, tolerability, and efficacy of treatment with brexpiprazole flexible-dose 1-4 mg/day. Methods: Patients rolled over into this 52-week open-label study (amended to 26 weeks towards the end) from three randomized, double-blind, placebo-controlled Phase 3 studies...
February 3, 2018: International Journal of Neuropsychopharmacology
Mart Schiefer, Lizza E L Hendriks, Trang Dinh, Ulrich Lalji, Anne-Marie C Dingemans
An increasing number of tyrosine kinase inhibitors (TKIs) are available for the treatment of non-small cell lung cancer (NSCLC). QT prolongation is one of the known, but relatively rare, adverse events of several TKIs (e.g. osimertinib, crizotinib, ceritinib). Screening for QT prolongation in (high risk) patients is advised for these TKIs. When a QT prolongation develops, the physician is challenged with the question whether to (permanently) discontinue the TKI. In this perspective, we report on a patient who developed a grade III QT prolongation during osimertinib (a third-generation epidermal growth factor receptor [EGFR]-TKI) treatment...
March 2018: European Journal of Cancer
James Winter, Michael Tipton, Michael J Shattock
This study tested the hypothesis that concomitant sympathetic and parasympathetic stimulation ("autonomic conflict") may act as a trigger for arrhythmia in long QT syndrome (LQTS). Studies were performed in isolated innervated rabbit hearts treated with clofilium (100 nmol/L); a potassium channel blocker. The influence of vagus nerve stimulation (VNS) on spontaneous ventricular arrhythmia was assessed in the absence/presence of sustained noradrenaline perfusion (100 nmol/L) and with sudden adrenergic stress (injections of noradrenaline into the perfusion line)...
February 2, 2018: Journal of Molecular and Cellular Cardiology
Ibrahim El-Battrawy, Zhihan Zhao, Huan Lan, Jan-Dierk Schünemann, Katherine Sattler, Fanis Buljubasic, Bence Patocskai, Xin Li, Gökhan Yücel, Siegfried Lang, Daniel Nowak, Lukas Cyganek, Karen Bieback, Jochen Utikal, Wolfram-Hubertus Zimmermann, Ursula Ravens, Thomas Wieland, Martin Borggrefe, Xiao-Bo Zhou, Ibrahim Akin
BACKGROUND AND PURPOSE: Previous studies revealed that Takotsubo cardiomyopathy (TTC), a transient disorder of ventricular dysfunction affecting predominantly postmenopausal women, is associated with acquired long QT syndrome and arrhythmias, but the exact pathophysiologic mechanism is unknown. Our aim is to investigate the electrophysiological mechanism for QT-prolongation in TTC-patients by using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). METHODS: hiPSC-CMs, which were generated from human skin fibroblasts of three healthy donors, were treated by estradiol (10μM for one week) and a toxic concentration of isoprenaline (Iso, 1mM for 2h)...
March 1, 2018: International Journal of Cardiology
Omer Yiginer, Mehmet Dogan, Ismet Gun, Huseyin Tayfun Kutlu, Gokhan Degirmencioglu, İlkin Guliyev, Alptug Tokatli, Fethi Kilicaslan
BACKGROUND: The frequency of arrhythmic death developing without a structural cardiac disease is higher in women. Also female gender is an independent risk factor regarding developing Torsades des Pointes. Several studies have been conducted on the effects of physiological and therapeutic sex hormones on cardiac conduction system. AIM: In this study we aim to examine the effect of hormonal changes occurring during in vitro fertilization treatment and especially supraphysiological E2 levels on ventricular repolarization parameters...
February 5, 2018: Kardiologia Polska
Christian Ellermann, Magdalena Sterneberg, Simon Kochhäuser, Dirk G Dechering, Michael Fehr, Lars Eckardt, Gerrit Frommeyer
Aims: Antazoline is a first-generation antihistamine with antiarrhythmic properties. This study examines potential electrophysiological effects of antazoline in short-QT-syndrome (SQTS) and long-QT-syndrome (LQTS). Methods and results: Sixty-five rabbit hearts were Langendorff-perfused. Action potential duration at 90% of repolarization (APD90), QT-interval, spatial dispersion (DISP), and effective refractory period (ERP) were measured. The IK, ATP-opener pinacidil (1 µM, n = 14) reduced APD90 (-14 ms, P < 0...
January 25, 2018: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
Weiqing Liu, Tae Yun Kim, Xiaodong Huang, Michael B Liu, Gideon Koren, Bum-Rak Choi, Zhilin Qu
T-wave alternans (TWA) and irregular beat-to-beat T-wave variability or T-wave lability (TWL), the ECG manifestations of action potential duration (APD) alternans and variability, are precursors of ventricular arrhythmias in long QT syndromes. TWA and TWL in patients tend to occur at normal heart rates and are usually potentiated by bradycardia. Whether or how TWA and TWL at normal or slow heart rates are causally linked to arrhythmogenesis remains unknown. In this study, we used computer simulations and experiments of a transgenic rabbit model of long QT syndrome to investigate the underlying mechanisms...
January 29, 2018: Journal of Physiology
Christoph Klivinyi, Helmar Bornemann-Cimenti
Long QT syndrome is a cardiac repolarization disorder and is associated with an increased risk of torsades de pointes. The acquired form is most often attributable to administration of specific medications and/or electrolyte imbalance. This review provides insights into the risk for QT prolongation associated with drugs frequently used in the treatment of chronic pain. In the field of pain medicine all the major drug classes (i.e. NSAIDs, opioids, anticonvulsive and antidepressant drugs, cannabinoids, muscle relaxants) contain agents that increase the risk of QT prolongation...
January 2018: Korean Journal of Pain
Yanan Jiang, Weijie Du, Qun Chu, Ying Qin, Gulnara Tuguzbaeva, Hui Wang, Anqi Li, Guiyang Li, Yanyao Li, Lu Chai, Er Yue, Xi Sun, Zhiguo Wang, Valentin Pavlov, Baofeng Yang, Yunlong Bai
BACKGROUND/AIMS: Arsenic trioxide (ATO) is a known anti-acute promyelocytic leukemia (APL) reagent, whose clinical applications are limited by its serious cardiac toxicity and fatal adverse effects, such as sudden cardiac death resulting from long QT syndrome (LQTS). The mechanisms of cardiac arrhythmia due to ATO exposure still need to be elucidated. Long non-coding RNAs (lncRNAs) are emerging as major regulators of various pathophysiological processes. This study aimed to explore the involvement of lncRNAs in ATO-induced LQTS in vivo and in vitro...
January 15, 2018: Cellular Physiology and Biochemistry
Abhishek Rathore, Bharatraj Banavalikar, Jayaprakash Shenthar, Debashish Acharya, Javed Parvez, Kikkeri Hemanna Setty Srinivasa
Complete atrioventricular (AV) block in association with Takotsubo syndrome (TS) has been well recognized, but the cause and effect relationship has not been elucidated. We describe a 78-year-old female who presented with complete AV block but one week later developed new-onset, diffuse T-wave inversions, QT prolongation, and acceleration of junctional escape rate. Left ventriculogram revealed features typical of TS. One year after permanent pacemaker implantation, complete AV block persisted despite the reversal of wall motion defects implying that conduction abnormality was the trigger of TS rather than its consequence...
January 9, 2018: Indian Pacing and Electrophysiology Journal
Gerrit Frommeyer, Julius Krawczyk, Christian Ellermann, Nils Bögeholz, Simon Kochhäuser, Dirk G Dechering, Michael Fehr, Lars Eckardt
AIMS: A significant antiarrhythmic potential of ryanodine receptor inhibition was reported in experimental studies. The aim of the present study was to assess potential antiarrhythmic effects of dantrolene in an experimental whole-heart model of drug-induced long-QT syndrome (LQTS). METHODS: In 12 isolated rabbit hearts long-QT-2-syndrome was simulated by infusion of erythromycin (300μM). 12 rabbit hearts were treated with veratridine (0.5μM) to mimic long-QT-3-syndrome...
January 4, 2018: Journal of Cardiovascular Electrophysiology
Lei Huang, Kuo-Ho Wu, Liyong Zhang, Qinchuan Wang, Shuangbo Tang, Qiuping Wu, Pei-Hsiu Jiang, Jim Jung-Ching Lin, Jian Guo, Lin Wang, Shih-Hurng Loh, Jianding Cheng
BACKGROUND: Sudden unexplained nocturnal death syndrome (SUNDS) remains an autopsy negative entity with unclear etiology. Arrhythmia has been implicated in SUNDS. Mutations/deficiencies in intercalated disc components have been shown to cause arrhythmias. Human cardiomyopathy-associated 1 (XIRP1) and 3 (XIRP2) are intercalated disc-associated, Xin repeats-containing proteins. Mouse Xirp1 is necessary for the integrity of intercalated disc and for the surface expression of transient outward and delayed rectifier K+ channels, whereas mouse Xirp2 is required for Xirp1 intercalated disc localization...
January 6, 2018: Journal of the American Heart Association
Carmela Coppola, Anna Rienzo, Giovanna Piscopo, Antonio Barbieri, Claudio Arra, Nicola Maurea
The side effects of anticancer drugs still play a critical role in survival and quality of life. Although the recent progresses of cancer therapies have significantly improved the prognosis of oncologic patients, side effects of antineoplastic treatments are still responsible for the increased mortality of cancer survivors. Cardiovascular toxicity is the most dangerous adverse effect induced by anticancer therapies. A survey conducted by the National Health and Nutrition Examination, showed that 1807 cancer survivors followed up for seven years: 51% died of cancer and 33% of heart disease (Vejpongsa and Yeh, 2014)...
February 2018: Cancer Treatment Reviews
Cunjin Luo, Kuanquan Wang, Henggui Zhang
A gain-of-function KCNJ2 D172N mutation in KCNJ2-encoded Kir2.1 channels underlies one form of short QT syndrome (SQT3), which is associated with increased susceptibility to arrhythmias and sudden death. Anti-malarial drug chloroquine was reported as an effective inhibitor of Kir2.1 channels. Using biophysically-detailed human ventricle computer models, this study assessed the effects of chloroquine on SQT3. The ten Tusscher et al. model of human ventricular cell action potential was modified to recapitulate functional changes in the inward rectifier K+ current (IK1) due to heterozygous and homozygous forms of the D172N mutation...
December 5, 2017: Oncotarget
Ai Kojima, Fumiaki Shikata, Toru Okamura, Takashi Higaki, Seiko Ohno, Minoru Horie, Shunji Uchita, Yujiro Kawanishi, Kenji Namiguchi, Takumi Yasugi, Hironori Izutani
BACKGROUND: Congenital long QT syndrome (LQTS) can cause ventricular arrhythmic events with syncope and sudden death resulting from malignant torsades de pointes (TdP) followed by ventricular fibrillations (VFs). However, the syndrome is often overlooked prior to the development of arrhythmic events in patients with congenital heart diseases demonstrating right bundle branch block on electrocardiogram (ECG). We present a case of an adult patient with congenital heart disease who developed VFs postoperatively, potentially due to his mutation in a LQTS related gene, which was not identified on preoperative assessment due to incomplete evaluation of his family history...
December 19, 2017: Journal of Cardiothoracic Surgery
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