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https://www.readbyqxmd.com/read/28534204/-ventricular-arrhythmias-in-ion-channel-diseases
#1
REVIEW
Christian Wolpert, Mara Vogel, Christian Nagel, Claudia Herrera-Siklody, Norman Rüb
In patients with ion channel disease the predominant arrhythmias are polymorphic ventricular tachycardias (VT), torsade de pointes tachycardia and ventricular fibrillation (VF). In only extremely rare cases is very rapid monomorphic ventricular tachycardia observed. This is why implantable cardioverter-defibrillators (ICDs) should always be programmed for treatment of VF only with high detection rates to avoid inappropriate discharges. In idiopathic VF and catecholaminergic polymorphic ventricular tachycardia (CPVT), no baseline electrocardiographic abnormalities can be detected, whereas in Brugada syndrome, long QT syndrome, early repolarisation syndrome and Anderson-Tawil syndrome alterations of the baseline ECG are very important to identify patients at risk...
May 22, 2017: Herzschrittmachertherapie & Elektrophysiologie
https://www.readbyqxmd.com/read/28527921/drug-induced-fatal-arrhythmias-acquired-long-qt-and-brugada-syndromes
#2
REVIEW
Isik Turker, Tomohiko Ai, Hideki Itoh, Minoru Horie
Since the early 1990s, the concept of primary "inherited" arrhythmia syndromes or ion channelopathies has evolved rapidly as a result of revolutionary progresses made in molecular genetics. Alterations in genes coding for membrane proteins such as ion channels or their associated proteins responsible for the generation of cardiac action potentials (AP) have been shown to cause specific malfunctions which eventually lead to cardiac arrhythmias. These arrhythmic disorders include congenital long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, progressive cardiac conduction disease, etc...
May 17, 2017: Pharmacology & Therapeutics
https://www.readbyqxmd.com/read/28525920/torsade-de-pointes-arrhythmias-arise-at-the-site-of-maximal-heterogeneity-of-repolarization-in-the-chronic-complete-atrioventricular-block-dog
#3
Albert Dunnink, Thom R G Stams, Alexandre Bossu, Veronique M F Meijborg, Jet D M Beekman, Sofieke C Wijers, Jacques M T De Bakker, Marc A Vos
Aims: The chronic complete atrioventricular block (CAVB) dog is highly sensitive for drug-induced torsade de pointes (TdP) arrhythmias. Focal mechanisms have been suggested as trigger for TdP onset; however, its exact mechanism remains unclear. In this study, detailed mapping of the ventricles was performed to assess intraventricular heterogeneity of repolarization in relation to the initiation of TdP. Methods and results: In 8 CAVB animals, 56 needles, each containing 4 electrodes, were inserted in the ventricles...
May 1, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28522677/synergistic-effect-of-dofetilide-and-mexiletine-on-prevention-of-atrial-fibrillation
#4
Guizhi Liu, Xiaolin Xue, Chuanyu Gao, Jiaqi Huang, Datun Qi, Yanzhou Zhang, Jian-Zeng Dong, Chang-Sheng Ma, Gan-Xin Yan
BACKGROUND: Although atrial fibrillation (AF) is the most common abnormal heart rhythm and its prevalence continues to rise, there is a marked paucity of effective and safe antiarrhythmic drugs for AF. This study was done to test whether combined use of dofetilide and mexiletine exhibits not only a synergistic effect on AF suppression but also a safer profile in drug-induced ventricular proarrhythmias. METHODS AND RESULTS: The effects of dofetilide plus mexiletine on atrial effective refractory period (ERP), AF inducibility, QT, and QT-related ventricular arrhythmias were studied using the isolated arterially perfused rabbit atrial and ventricular wedge preparations...
May 18, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28516454/a-multiscale-computational-modelling-approach-predicts-mechanisms-of-female-sex-risk-in-the-setting-of-arousal-induced-arrhythmias
#5
Pei-Chi Yang, Laura L Perissinotti, Fernando López-Redondo, Yibo Wang, Kevin R DeMarco, Mao-Tsuen Jeng, Igor Vorobyov, Robert D Harvey, Junko Kurokawa, Sergei Y Noskov, Colleen E Clancy
Female sex is a risk factor for inherited and acquired Long-QT associated Torsade de Pointes (TdP) arrhythmias, and sympathetic discharge is a major factor in triggering TdP in female Long-QT syndrome patients. We used a combined experimental and computational approach to predict 'the perfect storm' of hormone concentration, IKr block, and sympathetic stimulation that induces arrhythmia in females with inherited and acquired Long-QT. More specifically, we developed mathematical models of acquired and inherited Long-QT syndrome in male and female ventricular human myocytes by combining effects of a hormone and a hERG blocker dofetilide or hERG mutations...
May 18, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28511997/thorough-qt-tqt-studies-concordance-with-torsadogenesis-and-an-evolving-cardiac-safety-testing-paradigm
#6
Barbara Wiśniowska, Zofia Tylutki, Sebastian Polak
Since 2005, when the International Conference on Harmonisation (ICH) E14 guideline was adopted, no drug has been withdrawn because of QTc prolongation or torsade de pointes arrhythmia. There are, however, costs associated with this success. In addition to the time and money invested, thorough QT (TQT) studies have limited the efficiency of the drug development pipeline. In this paper, we discuss the relevance of TQT trials as a tool for proarrhythmic risk prediction as a part of the debate regarding their usefulness...
May 13, 2017: Drug Discovery Today
https://www.readbyqxmd.com/read/28507587/an-unusual-etiology-of-torsade-de-pointes-induced-syncope
#7
Marco Morosin, Ermanno Dametto, Federica Del Bianco, Marco Brieda, Gian L Nicolosi
No abstract text is available yet for this article.
April 1, 2017: Archives of Medical Science: AMS
https://www.readbyqxmd.com/read/28496937/amiodarone-induced-third-degree-atrioventricular-block-and-extreme-qt-prolongation-generating-torsade-des-pointes-in-paroxysmal-atrial-fibrillation
#8
Orlando Robert Sequeira, Nelson Javier Aquino, Nancy Beatriz Gómez, Laura Beatriz García, Cristina Cáceres, Oscar A Lovera, Osmar Antonio Centurión
Amiodarone is still the most potent antiarrhythmic drug in the prevention of life threatening ventricular arrhythmias and demonstrates a very low incidence of torsade de pointes. An unusual case of an 81-year-old woman who developed serious abnormalities of the conduction system of the heart and torsade des pointes during intravenous infusion of amiodarone for the treatment of paroxysmal atrial fibrillation is described. To the best of our knowledge, this is the first case showing an association of intravenous amiodarone-induced third degree atrioventricular block and extreme QT interval prolongation generating torsade des pointes in a patient with paroxysmal atrial fibrillation who required an implantable cardioverter-defibrillator...
October 2016: Journal of Atrial Fibrillation
https://www.readbyqxmd.com/read/28494415/studies-on-curative-efficacy-of-monoterpene-eugenol-on-anti-leukemic-drug-arsenic-trioxide-induced-cardiotoxicity
#9
Prakash Binu, Nellikunnath Priya, Surendran Abhilash, Radhakrishnan Chandraprabha Vineetha, Raveendran Harikumaran Nair
BACKGROUND: Arsenic trioxide (As2O3) is emerging as a frontline agent for the treatment of acute promyelocytic leukemia (APL) but the therapeutic application is limited by its toxicity. QT prolongation, torsades de pointes and sudden cardiac death have been implicated in the As2O3 therapy. So eugenol is a monoterpene compound is well known for its antioxidant properties and protective effect on the cardiovascular system. OBJECTIVE: In this study, the cardioprotective effect of eugenol on cardiac electrical conductivity, tissue electrolytes, myocardial markers, antioxidant system, lipid peroxidation and nitric oxide production was investigated in male Wistar rats treated with arsenic trioxide...
May 7, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28491783/atrioventricular-block-and-pause-dependent-torsade-de-pointes
#10
Mustafa Dohadwala, Fayak Kamili, Na Mark Estes, Munther Homoud
No abstract text is available yet for this article.
February 2017: HeartRhythm Case Reports
https://www.readbyqxmd.com/read/28491728/a-case-of-takotsubo-cardiomyopathy-showing-two-modes-of-initiation-for-ventricular-fibrillation-augmented-j-wave-and-torsade-de-pointes-with-qt-prolongation
#11
Masato Shimizu, Mitsuhiro Nishizaki, Noriyoshi Yamawake, Hiroyuki Fujii, Harumizu Sakudara, Masayasu Hiraoka
No abstract text is available yet for this article.
September 2016: HeartRhythm Case Reports
https://www.readbyqxmd.com/read/28490617/systemic-inflammation-as-a-novel-qt-prolonging-risk-factor-in-patients-with-torsades-de-pointes
#12
Pietro Enea Lazzerini, Franco Laghi-Pasini, Iacopo Bertolozzi, Gabriella Morozzi, Sauro Lorenzini, Antonella Simpatico, Enrico Selvi, Maria Romana Bacarelli, Francesco Finizola, Francesca Vanni, Deana Lazaro, Ademuyiwa Aromolaran, Nabil El Sherif, Mohamed Boutjdir, Pier Leopoldo Capecchi
OBJECTIVE: Increasing evidence indicates systemic inflammation as a new potential cause of acquired long QT syndrome (LQTS), via cytokine-mediated changes in cardiomyocyte ion channels. Torsade de pointes (TdP) is a life-threatening polymorphic ventricular tachycardia occurring in patients with LQTS, usually when multiple QT-prolonging factors are simultaneously present. Since classical risk factors cannot fully explain TdP events in a number of patients, we hypothesised that systemic inflammation may represent a currently overlooked risk factor contributing to TdP development in the general population...
May 10, 2017: Heart: Official Journal of the British Cardiac Society
https://www.readbyqxmd.com/read/28489458/toxicokinetics-of-ibogaine-and-noribogaine-in-a-patient-with-prolonged-multiple-cardiac-arrhythmias-after-ingestion-of-internet-purchased-ibogaine
#13
Marieke Henstra, Liza Wong, Abdel Chahbouni, Noortje Swart, Cor Allaart, Ferdi Sombogaard
BACKGROUND: Ibogaine is an agent that has been evaluated as an unapproved anti-addictive agent for the management of drug dependence. Sudden cardiac death has been described to occur secondary to its use. We describe the clinical effects and toxicokinetics of ibogaine and noribogaine in a single patient. For this purpose, we developed a LC-MS/MS-method to measure ibogaine and noribogaine plasma-concentrations. We used two compartments with first order absorption. CASE DETAILS: The maximum concentration of ibogaine was 1...
July 2017: Clinical Toxicology
https://www.readbyqxmd.com/read/28488266/qt-interval-prolongation-in-opioid-agonist-treatment-analysis-of-continuous-12-lead-electrocardiogram-recordings
#14
Geoffrey K Isbister, Amanda L Brown, Anthony Gill, Alexander J Scott, Leonie Calver, Adrian J Dunlop
BACKGROUND: Methadone is a widely used opioid agonist treatment associated with QT prolongation and torsades des pointes. We investigated the QT interval in patients treated with methadone or buprenorphine using continuous 12-lead holter recordings. METHODS: We prospectively recorded 24 h holters in patients prescribed methadone or buprenorphine, compared to controls. After their normal dose a continuous 12-lead holter recorder was attached for 24 h. Digital electrocardiograms were extracted hourly from the holter recordings...
May 9, 2017: British Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/28486375/domperidone-for-lactation-what-health-care-providers-need-to-know
#15
Catherine A Sewell, Christina Y Chang, Miriam M Chehab, Christine P Nguyen
This commentary serves to raise health care provider awareness about the regulatory status and available evidence regarding domperidone for insufficient lactation. Breastfeeding provides significant health benefits for mothers and infants, and insufficient milk production remains the most common reason for early weaning. Domperidone, a dopamine receptor antagonist that may increase milk production, is not approved for any human use in the United States. It is approved in some countries for certain gastrointestinal disorders, but is not approved in any country for lactation enhancement...
May 5, 2017: Obstetrics and Gynecology
https://www.readbyqxmd.com/read/28480041/risk-of-qt-prolongation-and-torsade-de-pointes-associated-with-exposure-to-hydroxyzine-re-evaluation-of-an-established-drug
#16
Anne-Françoise Schlit, Annie Delaunois, Aurore Colomar, Branderley Claudio, Luca Cariolato, Rossen Boev, Jean-Pierre Valentin, Christopher Peters, Victor S Sloan, Jürgen W G Bentz
Several noncardiac drugs have been linked to cardiac safety concerns, highlighting the importance of post-marketing surveillance and continued evaluation of the benefit-risk of long-established drugs. Here, we examine the risk of QT prolongation and/or torsade de pointes (TdP) associated with the use of hydroxyzine, a first generation sedating antihistamine. We have used a combined methodological approach to re-evaluate the cardiac safety profile of hydroxyzine, including: (1) a full review of the sponsor pharmacovigilance safety database to examine real-world data on the risk of QT prolongation and/or TdP associated with hydroxyzine use and (2) nonclinical electrophysiological studies to examine concentration-dependent effects of hydroxyzine on a range of human cardiac ion channels...
June 2017: Pharmacology Research & Perspectives
https://www.readbyqxmd.com/read/28431243/cryo-em-structure-of-the-open-human-ether-%C3%A3-go-go-related-k-channel-herg
#17
Weiwei Wang, Roderick MacKinnon
The human ether-à-go-go-related potassium channel (hERG, Kv11.1) is a voltage-dependent channel known for its role in repolarizing the cardiac action potential. hERG alteration by mutation or pharmacological inhibition produces Long QT syndrome and the lethal cardiac arrhythmia torsade de pointes. We have determined the molecular structure of hERG to 3.8 Å using cryo-electron microscopy. In this structure, the voltage sensors adopt a depolarized conformation, and the pore is open. The central cavity has an atypically small central volume surrounded by four deep hydrophobic pockets, which may explain hERG's unusual sensitivity to many drugs...
April 20, 2017: Cell
https://www.readbyqxmd.com/read/28421842/the-management-of-ventricular-dysrhythmia-in-aconite-poisoning
#18
REVIEW
James M Coulson, Thomas M Caparrotta, John P Thompson
INTRODUCTION: Aconite poisoning is relatively rare but is frequently complicated by ventricular dysrhythmias, which may be fatal. Molecular basis of aconite alkaloid ventricular arrhythmogenicity: Aconite exerts its toxic effects due to the presence of an admixture of alkaloids present in all parts of the plant. The major target of these aconite alkaloids is the fast voltage-gates sodium channel, where they cause persistent activation. This blockade of the channel in the activated state promotes automaticity within the ventricular myocardium and the generation of ventricular arrhythmias...
June 2017: Clinical Toxicology
https://www.readbyqxmd.com/read/28405995/recurrent-ventricular-tachycardia-due-to-long-qt-syndrome
#19
Rambabu Singh, Kshitiz Nath, Archana
Long QT syndrome (LQTS) is a rare inherited heart condition in which delayed repolarization of the heart following a heartbeat, increases the risk of episodes of Torsades de pointes (TdP, a form of irregular heartbeat that originates from the ventricles). These episodes may lead to palpitations, fainting, and sudden death due to ventricular fibrillation. Episodes may be provoked by various stimuli, depending on the subtype of the condition. We are reporting a case of 37 years old male whom we diagnosed to have long QT syndrome on the basis of clinical and ECG findings...
December 2016: Journal of the Association of Physicians of India
https://www.readbyqxmd.com/read/28383310/short-term-variability-of-repolarization-is-superior-to-other-repolarization-parameters-in-the-evaluation-of-diverse-antiarrhythmic-interventions-in-the-chronic-av-block-dog
#20
A Bossu, R Varkevisser, Hdm Beekman, Mjc Houtman, Mag van der Heyden, M A Vos
Short-term variability (STV), to quantify beat-to-beat variability of repolarization (BVR), is a surrogate parameter that reliably identifies proarrhythmic risk in preclinical models. Examples include not only the use in the chronic atrioventricular block (CAVB) dog model whereby it was developed, but also in vulnerable patients with heart failure or drug-induced long QT syndrome. In the CAVB dog model, STV can specifically distinguish between safe and unsafe drugs in proarrhythmic screening. Conversely, this dog model also offers the possibility to evaluate antiarrhythmic strategies in a setting of Torsades de Pointes (TdP) induction with a standard IKr inhibitor...
March 31, 2017: Journal of Cardiovascular Pharmacology
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