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Worawan B Limpitikul, Ivy E Dick, David Tester, Nicole J Boczek, Pattraranee Limphong, Wanjun Yang, Myoung Hyun Choi, Jennifer Babich, Deborah DiSilvestre, Ronald J Kanter, Gordon F Tomaselli, Michael J Ackerman, David Yue
RATIONALE: Calmodulinopathies comprise a new category of potentially life-threatening genetic arrhythmia syndromes capable of producing severe long QT syndrome (LQTS) with mutations involving either CALM1, CALM2, or CALM3 The underlying basis of this form of LQTS is a disruption of Ca(2+)/CaM-dependent inactivation (CDI) of L-type Ca(2+) channels (LTCCs). OBJECTIVE: To gain insight into the mechanistic underpinnings of calmodulinopathies and devise new therapeutic strategies for the treatment of this form of LQTS...
October 20, 2016: Circulation Research
Jennifer L Smith, Corey L Anderson, Don E Burgess, Claude S Elayi, Craig T January, Brian P Delisle
The molecular mechanisms underlying congenital long QT syndrome (LQTS) are now beginning to be understood. New insights into the etiology and therapeutic strategies are emerging from heterologous expression studies of LQTS-linked mutant proteins, as well as inducible pluripotent stem cell derived cardiomyocytes (iPSC-CMs) from LQTS patients. This review focuses on the major molecular mechanism that underlies LQTS type 2 (LQT2). LQT2 is caused by loss of function (LOF) mutations in KCNH2 (also known as the human Ether-à-go-go-Related Gene or hERG)...
October 2016: Journal of Arrhythmia
Christopher Semsarian, Jodie Ingles
Sudden cardiac death (SCD) is a rare but devastating complication of a number of underlying cardiovascular diseases. While coronary artery disease and acute myocardial infarction are the most common causes of SCD in older populations, inherited cardiac disorders comprise a substantial proportion of SCD cases aged less than 40 years. Inherited cardiac disorders include primary inherited arrhythmogenic disorders such as familial long QT syndrome (LQTS), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and inherited cardiomyopathies, most commonly hypertrophic cardiomyopathy (HCM)...
October 2016: Journal of Arrhythmia
Yongkeun Cho
Medications such as ß-blockers are currently the primary treatment for patients with hereditary arrhythmia syndromes such as long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). However, these drugs are ineffective in some patients, and the other treatment option, that is implantable cardioverter defibrillator (ICD) implantation, is associated with significant complications in young and active patients. Left cardiac sympathetic denervation (LCSD) may reduce the wide gap between life-long ß-blocker medication and ICD implantation...
October 2016: Journal of Arrhythmia
Sayaka Sasaoka, Toshinobu Matsui, Yuuki Hane, Junko Abe, Natsumi Ueda, Yumi Motooka, Haruna Hatahira, Akiho Fukuda, Misa Naganuma, Shiori Hasegawa, Yasutomi Kinosada, Mitsuhiro Nakamura
Long QT syndrome (LQTS) is a disorder of the heart's electrical activity that infrequently causes severe ventricular arrhythmias such as a type of ventricular tachycardia called torsade de pointes (TdP) and ventricular fibrillation, which can be fatal. There have been no previous reports on the time-to-onset for LQTS based on data from spontaneous reporting systems. The aim of this study was to assess the time-to-onset of LQTS according to drug treatment. We analyzed the association between 113 drugs in 37 therapeutic categories and LQTS including TdP using data obtained from the Japanese Adverse Drug Event Report database...
2016: PloS One
Gerrit Frommeyer, Catharina Clauss, Christian Ellermann, Harilaos Bogossian, Dirk G Dechering, Simon Kochhäuser, Florian Reinke, Christian Pott, Lars Eckardt
AIMS: The antiarrhythmic drug vernakalant exerts antiarrhythmic effects in atrial fibrillation. Recent experimental data suggest interactions with the late sodium current and antiarrhythmic effects in ventricular arrhythmias. We aimed at investigating whether treatment with vernakalant reduces polymorphic ventricular tachycardia (VT) in an experimental model of Long-QT-syndrome (LQTS). METHODS AND RESULTS: Twenty-nine isolated rabbit hearts were assigned to two groups and treated with erythromycin (300 µM, n = 15) or veratridine (0...
October 4, 2016: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
James Rush Priest, Charles Gawad, Kristopher M Kahlig, Joseph K Yu, Thomas O'Hara, Patrick M Boyle, Sridharan Rajamani, Michael J Clark, Sarah T K Garcia, Scott Ceresnak, Jason Harris, Sean Boyle, Frederick E Dewey, Lindsey Malloy-Walton, Kyla Dunn, Megan Grove, Marco V Perez, Norma F Neff, Richard Chen, Katsuhide Maeda, Anne Dubin, Luiz Belardinelli, John West, Christian Antolik, Daniela Macaya, Thomas Quertermous, Natalia A Trayanova, Stephen R Quake, Euan A Ashley
Somatic mosaicism, the occurrence and propagation of genetic variation in cell lineages after fertilization, is increasingly recognized to play a causal role in a variety of human diseases. We investigated the case of life-threatening arrhythmia in a 10-day-old infant with long QT syndrome (LQTS). Rapid genome sequencing suggested a variant in the sodium channel NaV1.5 encoded by SCN5A, NM_000335:c.5284G > T predicting p.(V1762L), but read depth was insufficient to be diagnostic. Exome sequencing of the trio confirmed read ratios inconsistent with Mendelian inheritance only in the proband...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
Stefan A Mann, Mohammad Imtiaz, Annika Winbo, Annika Rydberg, Matthew D Perry, Jean-Philippe Couderc, Bronislava Polonsky, Scott McNitt, Wojciech Zareba, Adam P Hill, Jamie I Vandenberg
In-silico models of human cardiac electrophysiology are now being considered for prediction of cardiotoxicity as part of the preclinical assessment phase of all new drugs. We ask the question whether any of the available models are actually fit for this purpose. We tested three models of the human ventricular action potential, the O'hara-Rudy (ORD11), the Grandi-Bers (GB10) and the Ten Tusscher (TT06) models. We extracted clinical QT data for LQTS1 and LQTS2 patients with nonsense mutations that would be predicted to cause 50% loss of function in IKs and IKr respectively...
September 20, 2016: Journal of Molecular and Cellular Cardiology
Ehud Chorin, Aviram Hochstadt, Sami Viskin, Uri Rozovski, Ofer Havakuk, Adrian Baranchuk, Andres Enriquez, Boris Strasberg, Milton E Guevara-Valdivia, Manlio F Márquez, Héctor González-Pacheco, Can Hasdemir, Raphael Rosso
BACKGROUND: Female gender increases the risk of torsades de pointes (TdP) in the long QT syndrome, and this increased risk is assumed to be due to their longer QT interval. OBJECTIVE: The purpose of this study was to study the interplay between gender, duration of the QT interval, and risk of TdP during AV block. METHODS: We studied 250 patients (48% women) with AV block. QT interval was measured at the time of most severe bradycardia. We then constructed different receiver operating characteristic curves for the QTc of males and females for predicting TdP...
September 17, 2016: Heart Rhythm: the Official Journal of the Heart Rhythm Society
Kafa Walweel, Ye Win Oo, Derek R Laver
Cardiac output and rhythm depend on the release and the take-up of calcium from the sarcoplasmic reticulum (SR). Excessive diastolic calcium leak from the SR due to dysfunctional calcium release channels (RyR2) contributes to the formation of delayed after-depolarisations, which underlie the fatal arrhythmias that occur in heart failure and inherited syndromes. Calmodulin (CaM) is a calcium-binding protein that regulates target proteins and acts as a calcium sensor. CaM is comprised of two calcium binding EF-hand domains and a flexible linker...
September 14, 2016: Clinical and Experimental Pharmacology & Physiology
Edelmann J, Dobosz T, Sobieszczanska M, Kawecka-Negrusz M, Dreßler J, Nastainczyk-Wulf M
Congenital long QT-syndrome (LQTS) is an inherited cardiac arrhythmia, which is characterized by a prolonged QT interval which predisposes to sudden cardiac death due to ventricular arrhythmias. The altered functions are based on different mutations in LQTS-associated genes. In this study, we performed a mutation analysis for the detection of 125 LQTS-associated single nucleotide polymorphisms (SNPs) focused on the genes KCNQ1, KCNH2, and SCN5A by using the SNaPshot multiplex minisequencing technique. Furthermore, we investigated 152 autopsy-negative cases from younger adults and infants, as well as samples from patients with clinically suspicion for LQTS, in which we found two types of variations...
September 9, 2016: International Journal of Legal Medicine
Arthur A M Wilde, Arthur J Moss, Elizabeth S Kaufman, Wataru Shimizu, Derick R Peterson, Jesaia Benhorin, Coeli Lopes, Jeffrey A Towbin, Carla Spazzolini, Lia Crotti, Wojciech Zareba, Ilan Goldenberg, Jørgen K Kanters, Jennifer L Robinson, Ming Qi, Nynke Hofman, David J Tester, Connie R Bezzina, Marielle Alders, Takeshi Aiba, Shiro Kamakura, Yoshihiro Miyamoto, Mark L Andrews, Scott McNitt, Bronislava Polonsky, Peter J Schwartz, Michael J Ackerman
BACKGROUND: Risk stratification in patients with type 3 long-QT syndrome (LQT3) by clinical and genetic characteristics and effectiveness of β-blocker therapy has not been studied previously in a large LQT3 population. METHODS: The study population included 406 LQT3 patients with 51 sodium channel mutations; 391 patients were known to be event free during the first year of life and were the focus of our study. Clinical, electrocardiographic, and genetic parameters were acquired for patients from 7 participating LQT3 registries...
September 20, 2016: Circulation
Mika Kumakura, Koji Hara, Takeyoshi Sata
Although patients with congenital long QT syndrome (c-LQTS) are considered to be at high risk for anesthesia, few reports describe c-LQTS genotype-specific considerations for anesthesia. We describe a case of torsade de pointes (TdP) caused by sevoflurane in a patient with c-LQTS genotype 2 (LQT2). A 39-year-old woman diagnosed with c-LQTS was scheduled for an elective therapeutic abortion. Immediately after starting the operation, the patient developed TdP. Since pulseless ventricular tachycardia was sustained despite intravenous injection of lidocaine, defibrillation was performed...
September 2016: Journal of Clinical Anesthesia
Karolina Wesołowska, Marko Elovainio, Mikael Koponen, Annukka M Tuiskula, Mirka Hintsanen, Liisa Keltikangas-Järvinen, Ilmari Määttänen, Heikki Swan, Taina Hintsa
We examined whether long QT syndrome (LQTS) mutation carrier status or symptomatic LQTS are associated with depression, and whether there are sex differences in these potential relationships. The sample comprised 782 participants (252 men). Of the 369 genetically defined LQTS mutation carriers, 169 were symptomatic and 200 were asymptomatic. The control group consisted of 413 unaffected relatives. Depression was assessed using the Beck Depression Inventory-II (BDI-II). No association was found for LQTS mutation carrier status with depression...
August 23, 2016: Journal of Genetic Counseling
Bettina F Cuneo, Janette F Strasburger, Ronald T Wakai
INTRODUCTION: Fetal magnetocardiography (fMCG), the magnetic analog of ECG, has provided invaluable insight into the mechanisms of fetal arrhythmias. In the past 15years, we have evaluated over 300 fetuses with arrhythmia by fMCG. We review the unique characteristics and natural history of the long QT syndrome (LQTS) rhythms. METHODS: We reviewed the fMCGs of subjects referred with suspected LQTS based on either a positive family history or echo diagnosis of the LQTS rhythms (sinus bradycardia, ventricular tachycardia, or 2:1 AV conduction) to the Biomagnetism laboratory in the Department of Medical Physics, UW-Madison...
July 28, 2016: Journal of Electrocardiology
Zhifei Hou, Guoxiang Sun, Yong Guo
The present study demonstrated the use of the Linear Quantitative Profiling Method (LQPM) to evaluate the quality of Alkaloids of Sophora flavescens (ASF) based on chromatographic fingerprints in an accurate, economical and fast way. Both linear qualitative and quantitative similarities were calculated in order to monitor the consistency of the samples. The results indicate that the linear qualitative similarity (LQLS) is not sufficiently discriminating due to the predominant presence of three alkaloid compounds (matrine, sophoridine and oxymatrine) in the test samples; however, the linear quantitative similarity (LQTS) was shown to be able to obviously identify the samples based on the difference in the quantitative content of all the chemical components...
2016: PloS One
Carol A Harley, Greg Starek, David K Jones, Andreia S Fernandes, Gail A Robertson, João H Morais-Cabral
The human human ether-à-go-go-related gene (hERG) potassium channel plays a critical role in the repolarization of the cardiac action potential. Changes in hERG channel function underlie long QT syndrome (LQTS) and are associated with cardiac arrhythmias and sudden death. A striking feature of this channel and KCNH channels in general is the presence of an N-terminal Per-Arnt-Sim (PAS) domain. In other proteins, PAS domains bind ligands and modulate effector domains. However, the PAS domains of KCNH channels are orphan receptors...
August 30, 2016: Proceedings of the National Academy of Sciences of the United States of America
Kathryn E Waddell-Smith, Jian Li, Warren Smith, Jackie Crawford, Jonathan R Skinner
BACKGROUND: Long-term uninterrupted β-blockade significantly reduces cardiac events in long QT syndrome (LQTS). Despite this, data on nonadherence are scarce and quantified only on the day of cardiac arrest in LQTS literature. We aimed to describe β-blocker adherence, and predictors thereof, among patients with LQTS types 1 and 2. METHODS AND RESULTS: Electronic health records and pharmacy dispensing data were reviewed for 90 patients with LQTS 1 and 2 who reside in Auckland, New Zealand, during a 34-month period...
August 2016: Circulation. Arrhythmia and Electrophysiology
S A Immanuel, A Sadrieh, M Baumert, J P Couderc, W Zareba, A P Hill, J I Vandenberg
Long QT syndrome (LQTS) is an inherited disorder associated with prolongation of the QT/QTc interval on the surface electrocardiogram (ECG) and a markedly increased risk of sudden cardiac death due to cardiac arrhythmias. Up to 25% of genotype-positive LQTS patients have QT/QTc intervals in the normal range. These patients are, however, still at increased risk of life-threatening events compared to their genotype-negative siblings. Previous studies have shown that analysis of T-wave morphology may enhance discrimination between control and LQTS patients...
September 2016: Physiological Measurement
Aarti Dalal, Richard J Czosek, Joshua Kovach, Johannes C von Alvensleben, Santiago Valdes, Susan P Etheridge, Michael J Ackerman, Debbie Auld, Jeryl Huckaby, Courtney McCracken, Robert Campbell
OBJECTIVES: To identify the clinical presentation of children and adolescents affected by 1 of 4 cardiac conditions predisposing to sudden cardiac arrest: hypertrophic cardiomyopathy, long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and anomalous origin of the left coronary artery from the right sinus of Valsalva (ALCA-R). STUDY DESIGN: This was a retrospective review of newly diagnosed pediatric patients with hypertrophic cardiomyopathy, LQTS, CPVT, and ALCA-R referred for cardiac evaluation at 6 US centers from 2008 to 2014...
October 2016: Journal of Pediatrics
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