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Prolonged QT syndrome

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https://www.readbyqxmd.com/read/29784533/long-qt-syndrome-a-comprehensive-review-of-the-literature-and-current-evidence
#1
REVIEW
Syed Raza Shah, Ki Park
Long QT syndrome (LQT) represents a heterogeneous family of cardiac electrophysiologic disorders characterized by QT prolongation and T-wave abnormalities on the electrocardiogram. It is commonly associated with syncope, however, sudden cardiac death can occur due to torsades de pointes. LQT is a clinical diagnosis and should be suspected in individuals on the basis of clinical presentation, family history and electrocardiogram characteristics. Management is focused on the prevention of syncope and ultimately sudden death...
May 10, 2018: Current Problems in Cardiology
https://www.readbyqxmd.com/read/29769222/transient-outward-k-current-i-to-underlies-the-right-ventricular-initiation-of-polymorphic-ventricular-tachycardia-in-a-transgenic-rabbit-model-of-long-qt-syndrome-type-1
#2
Bum-Rak Choi, Weiyan Li, Dmitry Terentyev, Anatoli Y Kabakov, Mingwang Zhong, Colin M Rees, Radmila Terentyeva, Tae Yun Kim, Zhilin Qu, Xuwen Peng, Alain Karma, Gideon Koren
BACKGROUND: Sudden death in long-QT syndrome type 1 (LQT1), an inherited disease caused by loss-of-function mutations in KCNQ1, is triggered by early afterdepolarizations (EADs) that initiate polymorphic ventricular tachycardia (pVT). We investigated ionic mechanisms that underlie pVT in LQT1 using a transgenic rabbit model of LQT1. METHODS: Optical mapping, cellular patch clamping, and computer modeling were used to elucidate the mechanisms of EADs in transgenic LQT1 rabbits...
June 2018: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29759541/the-phenotypic-spectrum-of-a-mutation-hotspot-responsible-for-the-short-qt-syndrome
#3
Dan Hu, Yang Li, Jiancheng Zhang, Ryan Pfeiffer, Michael H Gollob, Jeff Healey, Daniel Toshio Harrell, Naomasa Makita, Haruhiko Abe, Yaxun Sun, Jihong Guo, Li Zhang, Ganxin Yan, Douglas Mah, Edward P Walsh, Harris B Leopold, Carla Giustetto, Fiorenzo Gaita, Agnieszka Zienciuk-Krajka, Andrea Mazzanti, Silvia G Priori, Charles Antzelevitch, Hector Barajas-Martinez
OBJECTIVES: This study sought to evaluate the phenotypic and functional expression of an apparent hotspot mutation associated with short QT syndrome (SQTS). BACKGROUND: SQTS is a rare channelopathy associated with a high risk of life-threatening arrhythmias and sudden cardiac death (SCD). METHODS: Probands diagnosed with SQTS and their family members were evaluated clinically and genetically. KCNH2 wild-type (WT) and mutant genes were transiently expressed in HEK293 cells, and currents were recorded using whole-cell patch clamp and action potential (AP) clamp techniques...
July 2017: JACC. Clinical Electrophysiology
https://www.readbyqxmd.com/read/29754923/enhanced-late-sodium-current-underlies-pro-arrhythmic-intracellular-sodium-and-calcium-dysregulation-in-murine-sodium-channelopathy
#4
Mathilde R Rivaud, Antonius Baartscheer, Arie O Verkerk, Leander Beekman, Sridharan Rajamani, Luiz Belardinelli, Connie R Bezzina, Carol Ann Remme
BACKGROUND: Long QT syndrome mutations in the SCN5A gene are associated with an enhanced late sodium current (INa,L ) which may lead to pro-arrhythmic action potential prolongation and intracellular calcium dysregulation. We here investigated the dynamic relation between INa,L , intracellular sodium ([Na+ ]i ) and calcium ([Ca2+ ]i ) homeostasis and pro-arrhythmic events in the setting of a SCN5A mutation. METHODS AND RESULTS: Wild-type (WT) and Scn5a1798insD/+ (MUT) mice (age 3-5 months) carrying the murine homolog of the SCN5A-1795insD mutation on two distinct genetic backgrounds (FVB/N and 129P2) were studied...
July 15, 2018: International Journal of Cardiology
https://www.readbyqxmd.com/read/29739726/new-onset-seizures-in-a-patient-with-long-qt-syndrome-lqts2-and-a-pathogenic-carboxyl-terminus-frameshift-variant-of-the-kcnh2-gene
#5
Katherine Zarroli, Henry Querfurth
In patients with Long QT Syndrome (LQTS), mutations in the potassium channel KCNH2 gene increase seizure susceptibility with missense mutations involving the pore region of the gene acting as a positive predictor of seizures. Seizures are less commonly reported in patients with carboxyl (C')-terminus mutations. This case report describes a young man who presented with syncope followed by a first seizure and was found to have LQTS caused by a pathogenic carboxyl-terminus deletion/frameshifting mutation of the KCNH2 gene...
May 5, 2018: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
https://www.readbyqxmd.com/read/29738372/paradoxical-effects-of-sodium-calcium-exchanger-inhibition-on-torsade-de-pointes-and-early-afterdepolarization-in-a-heart-failure-rabbit-model
#6
Po-Cheng Chang, Yu-Ying Lu, Hui-Ling Lee, Shien-Fong Lin, Yen Chu, Ming-Shien Wen, Chung-Chuan Chou
Calcium homeostasis plays an important role in development of early afterdepolarizations (EADs) and torsade de pointes (TdP). The role of sodium-calcium exchanger (NCX) inhibition in genesis secondary Ca rise and EADs-TdP is still debated. Dual voltage and intracellular Ca optical mapping were conducted in 6 control and 9 failing rabbit hearts. After baseline electrophysiological and optical mapping studies, E4031 was given to simulate long QT syndrome. ORM-10103 was then administrated to examine the electrophysiological effects on EAD-TdP development...
May 3, 2018: Journal of Cardiovascular Pharmacology
https://www.readbyqxmd.com/read/29736926/timothy-syndrome-like-condition-with-syndactyly-but-without-prolongation-of-the-qt-interval
#7
Rika Kosaki, Hiroshi Ono, Hiroshi Terashima, Kenjiro Kosaki
Timothy syndrome is characterized by a unique combination of a prolongation of the corrected QT interval of the electrocardiogram and bilateral cutaneous syndactyly of the fingers and the toes and is caused by heterozygous mutations in CACNA1C, a gene encoding a calcium channel. After the discovery of the CACNA1C gene as the causative gene for Timothy syndrome, patients with CACNA1C mutations with QT prolongation but without syndactyly were described. Here, we report a 5-year-old female patient with cutaneous syndactyly, developmental delay, and pulmonary hypertension...
May 7, 2018: American Journal of Medical Genetics. Part A
https://www.readbyqxmd.com/read/29731714/proton-pump-inhibitors-and-serum-magnesium-levels-in-patients-with-torsades-de-pointes
#8
Pietro E Lazzerini, Iacopo Bertolozzi, Francesco Finizola, Maurizio Acampa, Mariarita Natale, Francesca Vanni, Rosella Fulceri, Alessandra Gamberucci, Marco Rossi, Beatrice Giabbani, Michele Caselli, Ilaria Lamberti, Gabriele Cevenini, Franco Laghi-Pasini, Pier L Capecchi
Background: Torsades de pointes (TdP) is a life-threatening ventricular tachycardia occurring in long QT-syndrome patients. It usually develops when multiple QT-prolonging factors are concomitantly present, more frequently drugs and electrolyte imbalances. Since proton-pump inhibitors (PPIs)-associated hypomagnesemia is an increasingly recognized adverse event, PPIs were recently included in the list of drugs with conditional risk of TdP, despite only few cases of TdP in PPI users have been reported so far...
2018: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/29725305/development-of-a-high-throughput-flow-cytometry-assay-to-monitor-defective-trafficking-and-rescue-of-long-qt2-mutant-herg-channels
#9
Scott A Kanner, Ananya Jain, Henry M Colecraft
Long QT Syndrome (LQTS) is an acquired or inherited disorder characterized by prolonged QT interval, exertion-triggered arrhythmias, and sudden cardiac death. One of the most prevalent hereditary LQTS subtypes, LQT2, results from loss-of-function mutations in the hERG channel, which conducts I Kr , the rapid component of the delayed rectifier K+ current, critical for cardiac repolarization. The majority of LQT2 mutations result in Class 2 deficits characterized by impaired maturation and trafficking of hERG channels...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29707106/inhibition-of-aldose-reductase-2-by-a-benzofuroxane-derivative-bf-5m-increases-the-expression-of-kcne1-kcnq1-in-high-glucose-cultured-h9c2-cardiac-cells-and-sudden-cardiac-death
#10
Maria Consiglia Trotta, Monica Salerno, Anna Lisa Brigida, Vincenzo Monda, Antonietta Messina, Carmela Fiore, Roberto Avola, Renato Bernardini, Francesco Sessa, Gabriella Marsala, Guido N Zanghì, Giovanni Messina, Michele D'Amico, Clara Di Filippo
Long QT syndrome (LQTS) is characterized by prolonged QT interval, leading to sudden cardiac death. Hyperglycemia is an important risk factor for LQTS, inhibiting the cardiac rapid component delayed rectifier K+ current (Iks), responsible for QT interval. We previously showed that the new ALR2 inhibitor BF-5m supplies cardioprotection from QT prolongation induced by high glucose concentration in the medium, reducing QT interval prolongation and preserving morphology. Here we investigated the effects of BF-5m on cell cytotoxicity and viability in H9c2 cells, and on cellular potassium ion channels expression...
April 3, 2018: Oncotarget
https://www.readbyqxmd.com/read/29706893/determinants-of-isoform-specific-gating-kinetics-of-herg1-channel-combined-experimental-and-simulation-study
#11
Laura L Perissinotti, Pablo M De Biase, Jiqing Guo, Pei-Chi Yang, Miranda C Lee, Colleen E Clancy, Henry J Duff, Sergei Y Noskov
IKr is the rapidly activating component of the delayed rectifier potassium current, the ion current largely responsible for the repolarization of the cardiac action potential. Inherited forms of long QT syndrome (LQTS) (Lees-Miller et al., 1997) in humans are linked to functional modifications in the Kv11.1 (hERG) ion channel and potentially life threatening arrhythmias. There is little doubt now that hERG-related component of IKr in the heart depends on the tetrameric (homo- or hetero-) channels formed by two alternatively processed isoforms of hERG, termed hERG1a and hERG1b...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29698642/obesity-and-ventricular-repolarization-a-comprehensive-review
#12
REVIEW
Jad Omran, Brian P Bostick, Albert K Chan, Martin A Alpert
Obesity is known to be a strong predictor of sudden cardiac death. For this reason, concern exists that this association may be related to delayed ventricular repolarization (VR), which has been extensively studied in overweight and obese patients. The corrected QT interval (QTc) and QT or QTc dispersion have been the most commonly-used electrocardiographic methods for assessing VR. Multiple controlled studies demonstrated that QTc and QT or QTc dispersion were significantly longer/greater in overweight and obese subjects than in normal weight controls...
April 23, 2018: Progress in Cardiovascular Diseases
https://www.readbyqxmd.com/read/29697308/emerging-therapeutic-targets-in-the-short-qt-syndrome
#13
Jules C Hancox, Dominic G Whittaker, Chunyun Du, A Graham Stuart, Henggui Zhang
INTRODUCTION: Short QT Syndrome (SQTS) is a rare but dangerous condition characterised by abbreviated repolarisation, atrial and ventricular arrhythmias and risk of sudden death. Implantable cardioverter defibrillators (ICDs) are a first line protection against sudden death, but adjunct pharmacology is beneficial and desirable. AREAS COVERED: The genetic basis for genotyped SQTS variants (SQT1-SQT8) and evidence for arrhythmia substrates from experimental and simulation studies are discussed...
April 26, 2018: Expert Opinion on Therapeutic Targets
https://www.readbyqxmd.com/read/29691127/digenic-heterozigosity-in-scn5a-and-cacna1c-explains-the-variable-expressivity-of-the-long-qt-phenotype-in-a-spanish-family
#14
Paloma Nieto-Marín, Juan Jiménez-Jáimez, David Tinaquero, Silvia Alfayate, Raquel G Utrilla, María Del Mar Rodríguez Vázquez Del Rey, Francesca Perin, Geòrgia Sarquella-Brugada, Lorenzo Monserrat, Josep Brugada, Luis Tercedor, Juan Tamargo, Eva Delpón, Ricardo Caballero
INTRODUCTION AND OBJECTIVES: A known long QT syndrome-related mutation in Nav1.5 cardiac channels (p.R1644H) was found in 4 members of a Spanish family but only 1 of them showed prolongation of the QT interval. In the other 3 relatives, a novel missense mutation in Cav1.2 cardiac channels was found (p.S1961N). Here, we functionally analyzed p.S1961N Cav1.2 channels to elucidate whether this mutation regulates the expressivity of the long QT syndrome phenotype in this family. METHODS: L-type calcium current (ICaL ) recordings were performed by using the whole-cell patch-clamp technique in Chinese hamster ovary cells transiently transfected with native and/or p...
April 21, 2018: Revista Española de Cardiología
https://www.readbyqxmd.com/read/29688407/mental-stress-test-a-rapid-simple-and-efficient-test-to-unmask-long-qt-syndrome
#15
Pauline Etienne, François Huchet, Nathalie Gaborit, Julien Barc, Aurélie Thollet, Florence Kyndt, Béatrice Guyomarch, Hervé Le Marec, Flavien Charpentier, Jean-Jacques Schott, Richard Redon, Vincent Probst, Jean-Baptiste Gourraud
Aims: QT prolongation during mental stress test (MST) has been associated with familial idiopathic ventricular fibrillation. In long QT syndrome (LQTS), up to 30% of mutation carriers have normal QT duration. Our aim was to assess the QT response during MST, and its accuracy in the diagnosis of concealed LQTS. Methods and results: All patients who are carrier of a KCNQ1 or KCNH2 mutations without QT prolongation were enrolled. A control group was constituted of patients with negative exercise and epinephrine tests...
April 20, 2018: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/29677462/ondansetron-blocks-wildtype-and-p-f503l-variant-small-conductance-calcium-activated-potassium-channels
#16
Jum-Suk Ko, Shuai Guo, Jonathan Hassel, Patricia Celestino-Soper, Ty C Lynnes, James E Tisdale, James J Zheng, Stanley E Taylor, Tatiana Foroud, Michael D Murray, Richard J Kovacs, Xiaochun Li, Shien-Fong Lin, Zhenhui Chen, Matteo Vatta, Peng-Sheng Chen, Michael Rubart
The apamin-sensitive, small conductance, calcium-activated potassium (SK) current ( IKAS ) is encoded by KCNN genes. IKAS importantly contributes to cardiac repolarization in conditions associated with reduced repolarization reserve. To test the hypothesis that IKAS inhibition contributes to drug-induced long QT (diLQT) syndrome, we (1) screened for KCNN variants among patients with diLQT, (2) determined the properties of heterologously expressed wildtype and variant KCNN channels, and (3) determined if the 5-HT3 receptor antagonist ondansetron blocks IKAS ...
April 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/29657083/the-course-of-awake-breathing-disturbances-across-the-lifespan-in-rett-syndrome
#17
Daniel C Tarquinio, Wei Hou, Jeffrey L Neul, Gamze Kilic Berkmen, Jana Drummond, Elizabeth Aronoff, Jennifer Harris, Jane B Lane, Walter E Kaufmann, Kathleen J Motil, Daniel G Glaze, Steven A Skinner, Alan K Percy
Rett syndrome (RTT), an X-linked dominant neurodevelopmental disorder caused by mutations in MECP2, is associated with a peculiar breathing disturbance exclusively during wakefulness that is distressing, and can even prompt emergency resuscitation. Through the RTT Natural History Study, we characterized cross sectional and longitudinal characteristics of awake breathing abnormalities in RTT and identified associated clinical features. Participants were recruited from 2006 to 2015, and cumulative lifetime prevalence of breathing dysfunction was determined using the Kaplan-Meier estimator...
April 12, 2018: Brain & Development
https://www.readbyqxmd.com/read/29650123/interplay-between-genetic-substrate-qtc-duration-and-arrhythmia-risk-in-patients-with-long-qt-syndrome
#18
Andrea Mazzanti, Riccardo Maragna, Gaetano Vacanti, Nicola Monteforte, Raffaella Bloise, Maira Marino, Lorenzo Braghieri, Patrick Gambelli, Mirella Memmi, Eleonora Pagan, Massimo Morini, Alberto Malovini, Martin Ortiz, Luciana Sacilotto, Riccardo Bellazzi, Lorenzo Monserrat, Carlo Napolitano, Vincenzo Bagnardi, Silvia G Priori
BACKGROUND: Long QT syndrome (LQTS) is a common inheritable arrhythmogenic disorder, often secondary to mutations in the KCNQ1, KCNH2, and SCN5A genes. The disease is characterized by a prolonged ventricular repolarization (QTc interval) that confers susceptibility to life-threatening arrhythmic events (LAEs). OBJECTIVES: This study sought to create an evidence-based risk stratification scheme to personalize the quantification of the arrhythmic risk in patients with LQTS...
April 17, 2018: Journal of the American College of Cardiology
https://www.readbyqxmd.com/read/29648704/abnormal-ventricular-repolarization-in-long-qt-syndrome-carriers-is-related-to-short-left-ventricular-filling-time-and-attenuated-stroke-volume-response-during-exercise
#19
Dafni Charisopoulou, George Koulaouzidis, Annika Rydberg, Michael Y Henein
BACKGROUND: Long QT syndrome (LQTS) carriers are characterized by abnormal ventricular repolarization, prolonged systole, and mechanical dispersion. Prolonged left ventricular (LV) systole has been shown to result in disproportionate shortening of LV filling in other conditions. The aim of this study was to assess LV filling, diastolic function, and stroke volume (SV) response to dynamic exercise, in a group of LQTS carriers. METHODS: Forty-seven LQTS carriers (45 ± 15 years, 20 symptomatic) and 35 healthy individuals underwent bicycle stress echocardiogram...
April 12, 2018: Echocardiography
https://www.readbyqxmd.com/read/29625280/long-qt-syndrome-type-5-lite-defining-the-clinical-phenotype-associated-with-the-potentially-pro-arrhythmic-p-asp85asn-kcne1-common-genetic-variant
#20
Conor Lane, John R Giudicessi, Dan Ye, David J Tester, Ram K Rohatgi, J Martijn Bos, Michael J Ackerman
BACKGROUND: Long QT syndrome (LQTS) genetic test reports commonly exclude potentially pro-arrhythmic common variants such as p.Asp85Asn-KCNE1. OBJECTIVE: To determine if a discernible phenotype is associated with p.Asp85Asn-KCNE1 and if relatively common KCNE1 variants underlie transient QT prolongation pedigrees with negative commercial LQTS genetic tests. METHODS: Retrospective review was used to compare demographics, symptomatology, and QT parameters of individuals with p...
April 3, 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
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