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Kenichi Sasaki, Takeru Makiyama, Yoshinori Yoshida, Yimin Wuriyanghai, Tsukasa Kamakura, Suguru Nishiuchi, Mamoru Hayano, Takeshi Harita, Yuta Yamamoto, Hirohiko Kohjitani, Sayako Hirose, Jiarong Chen, Mihoko Kawamura, Seiko Ohno, Hideki Itoh, Ayako Takeuchi, Satoshi Matsuoka, Masaru Miura, Naokata Sumitomo, Minoru Horie, Shinya Yamanaka, Takeshi Kimura
INTRODUCTION: Human induced pluripotent stem cells (hiPSCs) offer a unique opportunity for disease modeling. However, it is not invariably successful to recapitulate the disease phenotype because of the immaturity of hiPSC-derived cardiomyocytes (hiPSC-CMs). The purpose of this study was to establish and analyze iPSC-based model of catecholaminergic polymorphic ventricular tachycardia (CPVT), which is characterized by adrenergically mediated lethal arrhythmias, more precisely using electrical pacing that could promote the development of new pharmacotherapies...
2016: PloS One
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
Naokata Sumitomo
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is induced by emotions or exercise in patients without organic heart disease and may be polymorphic or bidirectional in nature. The prognosis of CPVT is not good, and therefore prevention of sudden death is of utmost importance. Genetic variants of CPVT include RyR2, CASQ2, CALM2, TRD, and possibly KCNJ2 and ANK2 gene mutations. Hypotheses that suggest the causes of CPVT include weakened binding of FKBP12.6 and RyR2, a store overload-induced Ca(2+) release (SOICR), unzipping of intramolecular domain interactions in RyR2, and molecular and functional abnormalities caused by mutations in the CASQ2 gene...
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
Przemysław B Radwański, Hsiang-Ting Ho, Rengasayee Veeraraghavan, Lucia Brunello, Bin Liu, Andriy E Belevych, Sathya D Unudurthi, Michael A Makara, Silvia G Priori, Pompeo Volpe, Antonis A Armoundas, Wolfgang H Dillmann, Bjorn C Knollmann, Peter J Mohler, Thomas J Hund, Sándor Györke
BACKGROUND: Cardiac arrhythmias are a leading cause of death in the US. Vast majority of these arrhythmias including catecholaminergic polymorphic ventricular tachycardia (CPVT) are associated with increased levels of circulating catecholamines and involve abnormal impulse formation secondary to aberrant Ca(2+) and Na(+) handling. However, the mechanistic link between β-AR stimulation and the subcellular/molecular arrhythmogenic trigger(s) remains elusive. METHODS AND RESULTS: We performed functional and structural studies to assess Ca(2+) and Na(+) signaling in ventricular myocyte as well as surface electrocardiograms in mouse models of cardiac calsequestrin (CASQ2)-associated CPVT...
June 2016: JACC. Basic to Translational Science
Zhichao Xiao, Wenting Guo, Bo Sun, Donald J Hunt, Jinhong Wei, Yingjie Liu, Yundi Wang, Ruiwu Wang, Peter P Jones, Thomas G Back, S R Wayne Chen
Recent three-dimensional structural studies reveal that the Central domain of ryanodine receptor (RyR) serves as a transducer that converts long-range conformational changes into the gating of the channel pore. Interestingly, the Central domain encompasses one of the mutation hotspots (corresponding to amino acid residues 3778-4201) that contains a number of cardiac RyR (RyR2) mutations associated with catecholaminergic polymorphic ventricular tachycardia (CPVT) and atrial fibrillation (AF). However, the functional consequences of these Central domain RyR2 mutations are not well understood...
October 12, 2016: Journal of Biological Chemistry
Francesco Lodola, Diego Morone, Marco Denegri, Rossana Bongianino, Hiroko Nakahama, Lucia Rutigliano, Rosanna Gosetti, Giulia Rizzo, Alessandra Vollero, Michelangelo Buonocore, Carlo Napolitano, Gianluigi Condorelli, Silvia G Priori, Elisa Di Pasquale
Catecholaminergic Polymorphic Ventricular Tachycardia type 2 (CPVT2) is a highly lethal recessive arrhythmogenic disease caused by mutations in the calsequestrin-2 (CASQ2) gene. We have previously demonstrated that viral transfer of the wild-type (WT) CASQ2 gene prevents the development of CPVT2 in a genetically induced mouse model of the disease homozygous carrier of the R33Q mutation. In the present study, we investigated the efficacy of the virally mediated gene therapy in cardiomyocytes (CMs) differentiated from induced pluripotent stem cells (iPSCs) obtained from a patient carrying the homozygous CASQ2-G112+5X mutation...
October 6, 2016: Cell Death & Disease
Thomas M Roston, Wenting Guo, Andrew D Krahn, Ruiwu Wang, Filip Van Petegem, Shubhayan Sanatani, S R Wayne Chen, Anna Lehman
BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an ion channelopathy usually caused by gain-of-function mutations ryanodine receptor type-2 (RyR2). Left ventricular non-compaction (LVNC) is an often genetic cardiomyopathy. A rare LVNC-CPVT overlap syndrome may be caused by exon 3 deletion in RyR2. We sought to characterize the phenotypic spectrum and molecular basis of a novel RyR2 mutation identified in a family with both conditions. METHODS: Several members of an affected family underwent clinical and genetic assessments...
September 8, 2016: Journal of Electrocardiology
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
Zhen Tan, Zhichao Xiao, Jinhong Wei, Jingqun Zhang, Qiang Zhou, Chris D Smith, Alma Nani, Guogen Wu, Long-Sheng Song, Thomas G Back, Michael Fill, S R Wayne Wayne Chen
Beta-blockers are a standard treatment for heart failure and cardiac arrhythmias. There are about 30 commonly used beta-blockers representing a diverse class of drugs with different receptor affinities and pleiotropic properties. We reported that among 14 beta-blockers tested previously, only carvedilol effectively suppressed cardiac ryanodine receptor (RyR2) mediated spontaneous Ca(2+) waves during store Ca(2+) overload, also known as store-overload induced Ca(2+) release (SOICR). Given the critical role of SOICR in arrhythmogenesis, it is of importance to determine whether there are other beta-blockers that suppress SOICR...
September 13, 2016: Biochemical Journal
Xiaowei Zhong, Bo Sun, Alexander Vallmitjana, Tao Mi, Wenting Guo, Mingke Ni, Ruiwu Wang, Ang Guo, Henry J Duff, Anne M Gillis, Long-Sheng Song, Leif Hove-Madsen, Raul Benitez, S R Wayne Wayne Chen
Beat-to-beat alternations in the amplitude of the cytosolic Ca(2+) transient (Ca(2+) alternans) are thought to be the primary cause of cardiac alternans that can lead to cardiac arrhythmias and sudden death. Despite its important role in arrhythmogenesis, the mechanism underlying Ca(2+) alternans remains poorly understood. Here we investigated the role of cardiac ryanodine receptor (RyR2), the major Ca(2+) release channel responsible for cytosolic Ca(2+) transients, in cardiac alternans. Using a unique mouse model harboring a suppression-of-function (SOF) RyR2 mutation (E4872Q), we assessed the effect of genetically suppressing RyR2 function on Ca(2+) and action potential duration (APD) alternans in intact hearts, and electrocardiogram (ECG) alternans in vivo...
August 31, 2016: Biochemical Journal
C Paludan-Müller, G Ahlberg, J Ghouse, C Herfelt, J H Svendsen, S Haunsø, J K Kanters, M S Olesen
Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is a highly lethal cardiac arrhythmia disease occurring during exercise or psychological stress. CPVT has an estimated prevalence of 1:10,000 and has mainly been associated with variants in calcium-regulating genes. Identification of potential false-positive pathogenic variants was conducted by searching the Exome Aggregation Consortium (ExAC) database (n = 60,706) for variants reported to be associated with CPVT. The pathogenicity of the interrogated variants was assessed using guidelines from the American College of Medical Genetics and Genomics (ACMG) and in silico prediction tools...
August 19, 2016: Clinical Genetics
Nieves Gomez-Hurtado, Nicole J Boczek, Dmytro O Kryshtal, Christopher N Johnson, Jennifer Sun, Florentin R Nitu, Razvan L Cornea, Walter J Chazin, Melissa L Calvert, David J Tester, Michael J Ackerman, Björn C Knollmann
BACKGROUND: Calmodulin (CaM) mutations are associated with severe forms of long QT syndrome and catecholaminergic polymorphic ventricular tachycardia (CPVT). CaM mutations are found in 13% of genotype-negative long QT syndrome patients, but the prevalence of CaM mutations in genotype-negative CPVT patients is unknown. Here, we identify and characterize CaM mutations in 12 patients with genotype-negative but clinically diagnosed CPVT. METHODS AND RESULTS: We performed mutational analysis of CALM1, CALM2, and CALM3 gene-coding regions, in vitro measurement of CaM-Ca(2+) (Ca)-binding affinity, ryanodine receptor 2-CaM binding, Ca handling, L-type Ca current, and action potential duration...
August 2016: Circulation. Arrhythmia and Electrophysiology
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
Marcela K Preininger, Rajneesh Jha, Joshua T Maxwell, Qingling Wu, Monalisa Singh, Bo Wang, Aarti Dalal, Zachary T Mceachin, Wilfried Rossoll, Chadwick M Hales, Peter S Fischbach, Mary B Wagner, Chunhui Xu
Although β-blockers can be used to eliminate stress-induced ventricular arrhythmias in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT), this treatment is unsuccessful in ∼25% of cases. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from these patients have potential for use in investigating the phenomenon, but it remains unknown whether they can recapitulate patient-specific drug responses to β-blockers. This study assessed whether the inadequacy of β-blocker therapy in an individual can be observed in vitro using patient-derived CPVT iPSC-CMs...
September 1, 2016: Disease Models & Mechanisms
Hiro Kawata, Seiko Ohno, Takeshi Aiba, Heima Sakaguchi, Aya Miyazaki, Naokata Sumitomo, Tsukasa Kamakura, Ikutaro Nakajima, Yuko Y Inoue, Koji Miyamoto, Hideo Okamura, Takashi Noda, Kengo Kusano, Shiro Kamakura, Yoshihiro Miyamoto, Isao Shiraishi, Minoru Horie, Wataru Shimizu
BACKGROUND: The long-term prognosis of cardiac ryanodine receptor (RyR2) positive catecholaminergic polymorphic ventricular tachycardia (CPVT) patients after initiation of medical therapy has not been well investigated. This study aimed to assess the recurrence of fatal cardiac event after initiation of medical therapy inRyR2-positive CPVT patients. METHODS AND RESULTS: Thirty-fourRyR2-positive CPVT patients with a history of cardiac events were enrolled. All patients had medical treatment initiated after the first symptom or diagnosis...
August 25, 2016: Circulation Journal: Official Journal of the Japanese Circulation Society
Miguel Fernandez-Tenorio, Ernst Niggli
To initiate the contraction of cardiomyocytes, Ca(2+) is released from the SR to the cytosol via ryanodine receptors (RyRs), which are activated by the Ca(2+)-induced Ca(2+) release mechanism (CICR). The activity of RyRs is regulated by both, cytosolic and SR luminal Ca(2+). Deregulation of the CICR, by dysfunctional SR Ca(2+) release or uptake, is frequently associated with cardiac pathologies (e.g. arrhythmias, CPVT, heart failure). Recently, the interest to directly measure changes of the free Ca(2+) concentration within the SR ([Ca(2+)]SR) has led to the application of low affinity Ca(2+) indicators (mag-fluo-4, Fluo-5N) to follow changes of [Ca(2+)]SR in cardiomyocytes from some species...
July 9, 2016: Cell Calcium
Krystien Vv Lieve, Arthur A Wilde, Christian van der Werf
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare but severe genetic cardiac arrhythmia disorder, with symptoms including syncope and sudden cardiac death due to polymorphic VT or ventricular fibrillation typically triggered by exercise or emotions in the absence of structural heart disease. The cornerstone of medical therapy for CPVT is β-blockers. However, recently flecainide has been added to the therapeutic arsenal for CPVT. In this review we summarise current data on the efficacy and role of flecainide in the treatment of CPVT...
May 2016: Arrhythmia & Electrophysiology Review
Elizabeth Anne Greene, Ann Punnoose
Symptoms such as syncope and chest pain, especially if they are accompanied by palpitations or occur with exercise in any combination, require cardiac evaluation before adolescent athletes are allowed to return to the sports field. Some life-threatening conditions will likely be associated with a family history of HCM or LQTS, but the family history may not be discovered at the first medical visit. A family history of CPVT, for example, is hard to elicit unless this diagnosis has already been established in an affected family member...
December 2015: Adolescent Medicine: State of the Art Reviews
Mariana Burgos, Alvaro Arenas, Rodrigo Cabrera
BACKGROUND AND OBJECTIVE: Inherited long QT syndrome (LQTS) is a cardiac channelopathy characterized by a prolongation of QT interval and the risk of syncope, cardiac arrest, and sudden cardiac death. Genetic diagnosis of LQTS is critical in medical practice as results can guide adequate management of patients and distinguish phenocopies such as catecholaminergic polymorphic ventricular tachycardia (CPVT). However, extensive screening of large genomic regions is required in order to reliably identify genetic causes...
August 2016: Molecular Diagnosis & Therapy
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