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https://www.readbyqxmd.com/read/28343764/channelopathies-genetic-testing-and-risk-stratification
#1
Arthur A M Wilde, Ahmad Amin
The cardiac channelopathies are a group of diseases with (disease-) specific electrocardiographic (ECG) characteristics and a disease-specific risk of sudden cardiac death (SCD). This group includes the Long QT Syndromes (LQTS), Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), Brugada Syndrome (BrS), Short QT Syndromes (SQTS), and Early Repolarization Syndrome (ERS). In the past 2 decades the genetic basis for these disease entities has largely been unraveled and that, together with the identification of the genetic basis of the cardiomyopathies, has paved the way for the complete new field of Cardiogenetics...
March 18, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28334543/-functional-impact-of-herg-from-physiological-role-to-target-of-anticancer-therapy
#2
Júlia Šatková, Markéta Bébarová
The human ether-à-go-go related gene (hERG; officially designated as KCNH2) encodes the structure of protein forming α-subunit of voltage-gated ion channel which conducts the rapid component of delayed rectifier K+ current (IKr). This current plays an important role namely in the cardiac repolarization. Mutations in hERG result in inherited arrhythmogenic syndromes characterized by a lenghtening or shortening of QT interval on the electrocardiogram and by an increased occurrence of life-threatening arrhythmias...
2017: Vnitr̆ní Lékar̆ství
https://www.readbyqxmd.com/read/28316956/sudden-infant-death-syndrome-due-to-long-qt-syndrome-a-brief-review-of-the-genetic-substrate-and-prevalence
#3
REVIEW
Nikolaos S Ioakeimidis, Theodora Papamitsou, Soultana Meditskou, Zafiroula Iakovidou-Kritsi
The pathophysiological mechanisms which lead to sudden infant death syndrome (SIDS) are not completely understood. Cardiac channelopathies are a well-established causative factor with long QT syndrome (LQTS) being the most frequent one, accounting for approximately 12% of SIDS cases. The genetic substrate of the above arrhythmogenic syndrome has been thoroughly described but only specific gene mutations or polymorphisms have been identified as SIDS causative. The review will focus on the prevalence of LQTS-induced SIDS or near-SIDS cases and the mutations held responsible...
December 2017: Journal of Biological Research
https://www.readbyqxmd.com/read/28290961/kcnq1-gene-variants-in-large-asymptomatic-populations-considerations-for-genomic-screening-of-military-cohorts
#4
Paul Kruszka, Karin Weiss, Donald W Hadley
INTRODUCTION: The advances in genomic technology of large populations make the potential for genomic screening of military cohorts and recruits feasible, affording the potential to identify at-risk individuals before occurrence of potentially life-threatening events. Exploring sudden cardiac death, known to cause significant morbidity and mortality in young military service members, we focused on the most common gene associated with long QT syndrome (LQTS), KCNQ1. MATERIALS AND METHODS: Using the publicly available database Exome Aggregation Consortium as a surrogate for a military population, variants in KCNQ1 were filtered on the basis of population prevalence, classification as a disease mutation in the Human Gene Mutation database, and classification as pathogenic or likely pathogenic in the ClinVar database...
March 2017: Military Medicine
https://www.readbyqxmd.com/read/28279743/vectrocardiography-identifies-patients-with-electrocardiographically-concealed-long-qt-syndrome-eclqts
#5
Daniel Cortez, J Martijn Bos, Michael J Ackerman
BACKGROUND: Long QT syndrome (LQTS) and genotypic subtypes are associated with distinctive T wave patterns, arrhythmogenic triggers, and corrected QT interval (QTc) risk associations. Twenty percent of patients with LQTS have normal QTc values, electrographically concealed LQTS (ecLQTS). Vectorcardiography (VCG) has value for sudden cardiac death risk assessment. OBJECTIVE: To determine the utility of VCG to identify patients with ecLQTS. METHODS: We performed a retrospective review on patients with ecLQTS, defined as resting QTc values < 440 ms...
March 6, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28155223/evaluation-of-prolonged-qt-interval-structural-heart-disease-mimicking-long-qt-syndrome
#6
Adaya Weissler-Snir, Michael H Gollob, Vijay Chauhan, Melanie Care, Danna A Spears
BACKGROUND: In about 20-25% of patients with congenital long QT syndrome (LQTS) a causative pathogenic mutation is not found. The aim of this study was to explore the prevalence of alternative cardiac diagnoses among patients exhibiting prolongation of QT interval with negative genetic testing for LQTS genes. METHODS: We conducted a retrospective analysis of 239 consecutive patients who were evaluated in the inherited arrhythmia clinic at the Toronto General Hospital between July 2013 and December 2015 for possible LQTS...
February 3, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28024120/ion-channels-long-qt-syndrome-and-arrhythmogenesis-in-ageing
#7
Kamalan Jeevaratnam, Karan R Chadda, Samantha C Salvage, Haseeb Valli, Shiraz Ahmad, Andrew A Grace, Christopher L-H Huang
Ageing is associated with increased prevalences of both atrial and ventricular arrhythmias, reflecting disruption of the normal sequence of ion channel activation and inactivation generating the propagated cardiac action potential. Experimental models with specific ion channel genetic modifications have helped clarify the interacting functional roles of ion channels and how their dysregulation contributes to arrhythmogenic processes at the cellular and systems level. They have also investigated interactions between these ion channel abnormalities and age-related processes in producing arrhythmic tendency...
December 26, 2016: Clinical and Experimental Pharmacology & Physiology
https://www.readbyqxmd.com/read/27882731/reproducibility-of-corrected-qt-interval-in-pediatric-genotyped-long-qt-syndrome
#8
Yoshiharu Ogawa, Toshikatsu Tanaka, Sachiko Kido
Reproducibility of corrected QT interval (QTc), especially QTc after exercise, has not been thoroughly investigated. We reviewed charts of pediatric patients who underwent treadmill-exercise stress testing without medication multiple times within 1 year. In patients with long-QT syndrome (LQTS; n = 22), the discrepancy in QTc between two treadmill exercise stress tests using Fridericia's formula was 14 ± 12 ms at rest, 13 ± 12 ms 4 min after exercise, with a maximum of 14 ± 12 ms after exercise. There was no statistically significant difference in QTc between the two tests...
November 2016: Pediatrics International: Official Journal of the Japan Pediatric Society
https://www.readbyqxmd.com/read/27844191/-indications-for-implantable-loop-recorders-in-patients-with-channelopathies-and-ventricular-tachycardias
#9
Julia Köbe, Kristina Wasmer, Florian Reinke, Lars Eckardt
Implantable loop recorders (ILR) do not play a pivotal role in the current guidelines on ventricular arrhythmias except in identifying rhythm-symptom correlations if ventricular arrhythmias are assumed. Before a decision for a pure diagnostic implantable device is made, a thorough arrhythmic risk assessment is of major importance due to the potential lethal outcome of ventricular arrhythmias. Nevertheless, some clinical circumstances exist where long-term monitoring by an ILR may add significant information in electrical heart diseases, in patients with ventricular arrhythmias, or structural heart diseases and a potential risk of ventricular arrhythmias...
December 2016: Herzschrittmachertherapie & Elektrophysiologie
https://www.readbyqxmd.com/read/27761161/molecular-pathogenesis-of-long-qt-syndrome-type-2
#10
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
https://www.readbyqxmd.com/read/27626620/the-emerging-role-of-calmodulin-regulation-of-ryr2-in-controlling-heart-rhythm-the-progression-of-heart-failure-and-the-antiarrhythmic-action-of-dantrolene
#11
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-depolarizations, 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...
January 2017: Clinical and Experimental Pharmacology & Physiology
https://www.readbyqxmd.com/read/27539165/the-natural-history-of-fetal-long-qt-syndrome
#12
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...
November 2016: Journal of Electrocardiology
https://www.readbyqxmd.com/read/27516460/%C3%AE-blocker-adherence-in-familial-long-qt-syndrome
#13
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
https://www.readbyqxmd.com/read/27502104/clinical-presentation-of-pediatric-patients-at-risk-for-sudden-cardiac-arrest
#14
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
https://www.readbyqxmd.com/read/27390944/novel-long-qt-syndrome-associated-missense-mutation-l762f-in-cacna1c-encoded-l-type-calcium-channel-imparts-a-slower-inactivation-tau-and-increased-sustained-and-window-current
#15
Andrew P Landstrom, Nicole J Boczek, Dan Ye, Christina Y Miyake, Caridad M De la Uz, Hugh D Allen, Michael J Ackerman, Jeffrey J Kim
BACKGROUND: Mutations in the CACNA1C-encoded L-type calcium channel have been associated with Timothy syndrome (TS) with severe QT prolongation, syndactyly, facial dysmorphisms, developmental delay, and sudden death. Recently, patients hosting CACNA1C mutations with only long QT syndrome (LQTS) have been described. We sought to identify novel variants in CACNA1C associated with either TS or LQTS, and to determine the impact of the mutation on channel function. METHODS/RESULTS: Two probands were identified with mutations in CACNA1C, one with a TS-associated mutation, G406R, and a second with genotype-negative LQTS...
October 1, 2016: International Journal of Cardiology
https://www.readbyqxmd.com/read/27279603/is-there-a-role-for-genetics-in-the-prevention-of-sudden-cardiac-death
#16
Alessandro Faragli, Katherine Underwood, Silvia G Priori, Andrea Mazzanti
The identification of patients at risk for sudden cardiac death (SCD) is fundamental for both acquired cardiovascular diseases (such as coronary artery diseases, CAD) and inherited arrhythmia syndromes (such as the long-QT syndrome, LQTS). Genetics may play a role in both situations, although the potential to exploit this information to reduce the burden of SCD varies among these two groups. Concerning acquired cardiovascular diseases, which affect most of the general population, preliminary data suggest an association between genetics and the risk of dying suddenly...
September 2016: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/27260221/the-evolution-of-sports-participation-guidelines-and-the-influence-of-genotype-phenotype-correlation-in-long-qt-syndrome
#17
Matthew L Furst, Peter F Aziz
Congenital Long QT Syndrome (LQTS) results in abnormal ventricular repolarization in patients with otherwise structurally normal hearts. Following the initial clinical descriptions of LQTS, there has been a great deal of investigation into the genetic etiology and pathophysiology of these entities, with the goal of improved screening tools and understanding of associated risks. Through this work, heart rhythm experts continue to revise their recommendations regarding sports eligibility. We review the evolution of sports participation recommendations for LQTS...
May 9, 2016: Trends in Cardiovascular Medicine
https://www.readbyqxmd.com/read/27210307/transgenic-rabbit-models-to-investigate-the-cardiac-ion-channel-disease-long-qt-syndrome
#18
REVIEW
C N Lang, G Koren, K E Odening
Long QT syndrome (LQTS) is a rare inherited channelopathy caused mainly by different mutations in genes encoding for cardiac K(+) or Na(+) channels, but can also be caused by commonly used ion-channel-blocking and QT-prolonging drugs, thus affecting a much larger population. To develop novel diagnostic and therapeutic strategies to improve the clinical management of these patients, a thorough understanding of the pathophysiological mechanisms of arrhythmogenesis and potential pharmacological targets is needed...
July 2016: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/26927864/exercise-and-inherited-arrhythmias
#19
REVIEW
Christopher C Cheung, Zachary W M Laksman, Gregory Mellor, Shubhayan Sanatani, Andrew D Krahn
Sudden cardiac death (SCD) in an apparently healthy individual is a tragedy that prompts a series of investigations to identify the cause of death and to prevent SCD in potentially at-risk family members. Several inherited channelopathies and cardiomyopathies, including long QT syndrome (LQTS), catecholaminergic polymorphic ventricular cardiomyopathy (CPVT), hypertrophic cardiomyopathy (HCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC) are associated with exercise-related SCD. Exercise restriction has been a historical mainstay of therapy for these conditions...
April 2016: Canadian Journal of Cardiology
https://www.readbyqxmd.com/read/26897076/exercise-restrictions-for-patients-with-inherited-cardiac-conditions-current-guidelines-challenges-and-limitations
#20
REVIEW
Matthew Hammond-Haley, Riyaz S Patel, Rui Providência, Pier D Lambiase
Inherited primary arrhythmia syndromes are a clinically heterogeneous group of relatively uncommon but important inherited cardiac conditions that are associated with an increased risk of sudden cardiac death (SCD) in the setting of a structurally normal heart. These include long-QT syndrome (LQTS), Short-QT syndrome (SQTS), Brugada syndrome (BrS) and Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT). The cardiomyopathies represent the other major group of inherited cardiac conditions associated with SCD, of which hypertrophic cardiomyopathy (HCM) is the most common...
April 15, 2016: International Journal of Cardiology
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