1
|
Chimatapu SN, Schachter JL, Batra AS, Sirignano R, Okawa ER. A Pediatric Case of Refractory Torsades de Pointes in Autoimmune Hypothyroidism. JCEM CASE REPORTS 2024; 2:luae124. [PMID: 39011403 PMCID: PMC11247166 DOI: 10.1210/jcemcr/luae124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Indexed: 07/17/2024]
Abstract
Hypothyroidism can have a significant impact on cardiac contractility, vascular resistance, blood pressure, and cardiac rhythm. Ventricular arrhythmias induced by hypothyroidism are infrequently reported, especially in pediatric cases. A 15-year-old girl with autoimmune hypothyroidism experienced pulseless ventricular arrhythmias on 2 separate occasions because of nonadherence to levothyroxine medication. Subsequent investigations revealed an SCN5A mutation associated with Brugada syndrome. A loop recorder captured polymorphic ventricular tachycardia (PMVT), specifically Torsades de Pointes during her second event. Both arrhythmias were addressed only after stabilizing her thyroid hormone levels with replacement therapy. Although rare, patients with uncontrolled hypothyroidism may present with ventricular arrhythmias, particularly PMVT. The cornerstone of treatment for hypothyroidism-induced ventricular arrhythmia is thyroid replacement therapy. The identification of an SCN5A mutation unmasked by overt hypothyroidism emphasizes the need for a comprehensive cardiac evaluation in patients with hypothyroidism being assessed for PMVT.
Collapse
Affiliation(s)
- Sri Nikhita Chimatapu
- University of California, Los Angeles, Mattel Children's Hospital, Los Angeles, CA 90095, USA
| | - Jessica L Schachter
- Department of Cardiology, University of California Irvine Medical Center, Orange, CA 92868, USA
| | - Anjan S Batra
- Department of Cardiology, University of California Irvine Medical Center, Orange, CA 92868, USA
| | - Rachel Sirignano
- Children's Heart Institute, Memorial Care Miller Children's & Women's Hospital, Long Beach, CA 90806, USA
| | - Erin R Okawa
- University of California, Los Angeles, Mattel Children's Hospital, Los Angeles, CA 90095, USA
| |
Collapse
|
2
|
Hu RM, Song EJ, Tester DJ, Deschenes I, Ackerman MJ, Makielski JC, Tan BH. Expression defect of the rare variant/Brugada mutation R1512W depends upon the SCN5A splice variant background and can be rescued by mexiletine and the common polymorphism H558R. Channels (Austin) 2021; 15:253-261. [PMID: 33535892 PMCID: PMC7872018 DOI: 10.1080/19336950.2021.1875645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/08/2021] [Accepted: 01/08/2021] [Indexed: 12/01/2022] Open
Abstract
Background : Mutations in SCN5A that decrease Na current underlie arrhythmia syndromes such as the Brugada syndrome (BrS). SCN5A in humans has two splice variants, one lacking a glutamine at position 1077 (Q1077del) and one containing Q1077. We investigated the effect of splice variant background on loss-of-function and rescue for R1512W, a mutation reported to cause BrS. Methods and results : We made the mutation in both variants and expressed them in HEK-293 cells for voltage-clamp study. After 24 hours of transfection, the current expression level of R1512W was reduced by ~50% in both Q1077del and Q1077 compared to the wild-type (WT) channel, respectively. The activation and inactivation midpoint were not different between WT and mutant channels in both splice variant backgrounds. However, slower time constants of recovery and enhanced intermediate inactivation were observed for R1512W/Q1077 compared with WT-Q1077, while the recovery and intermediate inactivation parameters of R1512W/Q1077del were similar to WT-Q1077del. Furthermore, both mexiletine and the common polymorphism H558R restored peak sodium current (INa) amplitude of the mutant channel by increasing the cell surface expression of SCN5A. Conclusion : These findings provide further evidence that the splice variant affects the molecular phenotype with implications for the clinical phenotype, and they provide insight into the expression defect mechanisms and potential treatment in BrS.
Collapse
Affiliation(s)
- Rou-Mu Hu
- Department of Cardiology, Heart Center & Beijing Key Laboratory of Hypertension, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Evelyn J. Song
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J. Tester
- Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
| | - Isabelle Deschenes
- Department of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, Frick Center for Heart Failure and Arrhythmia, the Ohio State University, Columbus, OH, USA
| | - Michael J. Ackerman
- Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
| | - Jonathan C. Makielski
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Bi-Hua Tan
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI, USA
- Department of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, Frick Center for Heart Failure and Arrhythmia, the Ohio State University, Columbus, OH, USA
| |
Collapse
|
3
|
Olaopa MA, Ai T, Chao B, Xiao X, Vatta M, Habecker BA. Phosphorylation of Lamin A/C at serine 22 modulates Na v 1.5 function. Physiol Rep 2021; 9:e15121. [PMID: 34806324 PMCID: PMC8606869 DOI: 10.14814/phy2.15121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 10/29/2021] [Accepted: 10/31/2021] [Indexed: 12/17/2022] Open
Abstract
Variants in the LMNA gene, which encodes for Lamin A/C, are associated with cardiac conduction disease (CCD). We previously reported that Lamin A/C variants p.R545H and p.A287Lfs*193, which were identified in CCD patients, decreased peak INa in HEK-293 cells expressing Nav 1.5. Decreased peak INa in the cardiac conduction system could account for patients' atrioventricular block. We found that serine 22 (Ser 22) phosphorylation of Lamin A/C was decreased in the p.R545H variant and hypothesized that lamin phosphorylation modulated Nav 1.5 activity. To test this hypothesis, we assessed Nav 1.5 function in HEK-293 cells co-transfected with LMNA variants or treated with the small molecule LBL1 (lamin-binding ligand 1). LBL1 decreased Ser 22 phosphorylation by 65% but did not affect Nav 1.5 function. To test the complete loss of phosphorylation, we generated a version of LMNA with serine 22 converted to alanine 22 (S22A-LMNA); and a version of mutant R545H-LMNA that mimics phosphorylation via serine 22 to aspartic acid 22 substitution (S22D-R545H-LMNA). We found that S22A-LMNA inhibited Lamin-mediated activation of peak INa by 63% and shifted voltage-dependency of steady-state inactivation of Nav 1.5. Conversely, S22D-R545H-LMNA abolished the effects of mutant R545H-LMNA on voltage-dependency but not peak INa . We conclude that Lamin A/C Ser 22 phosphorylation can modulate Nav 1.5 function and contributes to the mechanism by which R545H-LMNA alters Nav 1.5 function. The differential impact of complete versus partial loss of Ser 22 phosphorylation suggests a threshold of phosphorylation that is required for full Nav 1.5 modulation. This is the first study to link Lamin A/C phosphorylation to Nav 1.5 function.
Collapse
Affiliation(s)
- Michael A. Olaopa
- Department of Chemical Physiology and BiochemistryOregon Health & Science UniversityPortlandOregonUSA
- Krannert Institute of CardiologyDepartment of MedicineIndiana University School of MedicineIndianapolisIndianaUSA
| | - Tomohiko Ai
- Krannert Institute of CardiologyDepartment of MedicineIndiana University School of MedicineIndianapolisIndianaUSA
- Department of Clinical Laboratory MedicineJuntendo UniversityTokyoJapan
| | - Bo Chao
- Department of Chemical Physiology and BiochemistryOregon Health & Science UniversityPortlandOregonUSA
| | - Xiangshu Xiao
- Department of Chemical Physiology and BiochemistryOregon Health & Science UniversityPortlandOregonUSA
| | - Matteo Vatta
- Krannert Institute of CardiologyDepartment of MedicineIndiana University School of MedicineIndianapolisIndianaUSA
| | - Beth A. Habecker
- Department of Chemical Physiology and BiochemistryOregon Health & Science UniversityPortlandOregonUSA
| |
Collapse
|
4
|
Stawiarski K, Clarke JRD, Pollack A, Winslow R, Majumdar S. Ventricular fibrillation in Graves disease reveals a rare SCN5A mutation with W1191X variant associated with Brugada syndrome. HeartRhythm Case Rep 2021; 7:95-99. [PMID: 33665110 PMCID: PMC7897746 DOI: 10.1016/j.hrcr.2020.11.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Kristin Stawiarski
- Yale New Haven Health Heart and Vascular Center, Bridgeport Hospital, Bridgeport, Connecticut
| | - John-Ross D Clarke
- Yale New Haven Health Heart and Vascular Center, Bridgeport Hospital, Bridgeport, Connecticut
| | - Ari Pollack
- Yale New Haven Health Heart and Vascular Center, Bridgeport Hospital, Bridgeport, Connecticut
| | - Robert Winslow
- Yale New Haven Health Heart and Vascular Center, Bridgeport Hospital, Bridgeport, Connecticut
| | - Sachin Majumdar
- Yale New Haven Health Heart and Vascular Center, Bridgeport Hospital, Bridgeport, Connecticut
| |
Collapse
|
5
|
Hasebe H, Yokoya T, Murakoshi N, Kurebayashi N. Pilsicainide Administration Unmasks a Phenotype of Brugada Syndrome in a Patient with Overlap Syndrome due to the E1784K SCN5A Mutation. Intern Med 2020; 59:83-87. [PMID: 31484910 PMCID: PMC6995720 DOI: 10.2169/internalmedicine.3430-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Mutations in the cardiac sodium channel SCN5A can cause phenotypic overlap syndrome of long QT syndrome and Brugada syndrome. However, Brugada-type ST elevations in patients with overlap syndrome are often concealed, which creates a diagnostic challenge. A 38-year-old man was admitted due to ventricular fibrillation (VF). The 12-lead electrocardiogram showed a prolonged QT interval and saddleback-type ST elevation. Pilsicainide administration induced coved-type ST elevation and VF triggered by a single premature ventricular contraction. A genetic analysis showed an SCN5A c.5350G>A p.E1784K mutation. The present case suggests the importance of a drug administration test being performed in the clinical management of overlap syndrome.
Collapse
Affiliation(s)
- Hideyuki Hasebe
- Division of Arrhythmology, Shizuoka Saiseikai General Hospital, Japan
- Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Japan
| | - Tomoyo Yokoya
- Division of Arrhythmology, Shizuoka Saiseikai General Hospital, Japan
| | - Nobuyuki Murakoshi
- Cardiovascular Division, Faculty of Medicine, University of Tsukuba, Japan
| | | |
Collapse
|
6
|
Neubauer J, Wang Z, Rougier JS, Abriel H, Rieubland C, Bartholdi D, Haas C, Medeiros-Domingo A. Functional characterization of a novel SCN5A variant associated with long QT syndrome and sudden cardiac death. Int J Legal Med 2019; 133:1733-1742. [DOI: 10.1007/s00414-019-02141-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 08/06/2019] [Indexed: 12/14/2022]
|
7
|
Coppola G, Corrado E, Curnis A, Maglia G, Oriente D, Mignano A, Brugada P. Update on Brugada Syndrome 2019. Curr Probl Cardiol 2019; 46:100454. [PMID: 31522883 DOI: 10.1016/j.cpcardiol.2019.100454] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 07/29/2019] [Indexed: 12/15/2022]
Abstract
Brugada syndrome (BrS) was first described in 1992 as an aberrant pattern of ST segment elevation in right precordial leads with a high incidence of sudden cardiac death (SCD) in patients with structurally normal heart. It represents 4% ∼ 12% of all SCD and 20% of SCD in patients with structurally normal heart. The extremely wide genetic heterogeneity of BrS and other inherited cardiac disorders makes this new area of genetic arrhytmology a fascinating one. This review shows the state of art in diagnosis, management, and treatment of BrS focusing all the aspects regarding genetics and Preimplant Genetic Diagnosis (PGD) of embryos, overlapping syndromes, risk stratification, familial screening, and future perspectives. Moreover the review analyzes key points like electrocardiogram (ECG) criteria, the role of electrophysiological study (the role of ventricular programmed stimulation and the need of universal accepted protocol) and the importance of a correct risk stratification to clarify when implantable cardioverter defibrillator or a close follow-up is needed. In recent years, cardiovascular studies have been focused on personalized risk assessment and to determine the most optimal therapy for an individual. The BrS syndrome has also benefited of these advances although there remain several key points to be elucidated. We will review the present knowledge, progress made, and future research directions on BrS.
Collapse
|
8
|
Hu RM, Tester DJ, Li R, Sun T, Peterson BZ, Ackerman MJ, Makielski JC, Tan BH. Mexiletine rescues a mixed biophysical phenotype of the cardiac sodium channel arising from the SCN5A mutation, N406K, found in LQT3 patients. Channels (Austin) 2019; 12:176-186. [PMID: 29983085 PMCID: PMC6104686 DOI: 10.1080/19336950.2018.1475794] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Introduction: Individual mutations in the SCN5A-encoding cardiac sodium channel α-subunit usually cause a single cardiac arrhythmia disorder, some cause mixed biophysical or clinical phenotypes. Here we report an infant, female patient harboring a N406K mutation in SCN5A with a marked and mixed biophysical phenotype and assess pathogenic mechanisms. Methods and Results: A patient suffered from recurrent seizures during sleep and torsades de pointes with a QTc of 530 ms. Mutational analysis identified a N406K mutation in SCN5A. The mutation was engineered by site-directed mutagenesis and heterologously expressed in HEK293 cells. After 48 hours incubation with and without mexiletine, macroscopic voltage-gated sodium current (INa) was measured with standard whole-cell patch clamp techniques. SCN5A-N406K elicited both a significantly decreased peak INa and a significantly increased late INa compared to wide-type (WT) channels. Furthermore, mexiletine both restored the decreased peak INa of the mutant channel and inhibited the increased late INa of the mutant channel. Conclusion: SCN5A-N406K channel displays both “gain-of-function” in late INa and “loss-of-function” in peak INa density contributing to a mixed biophysical phenotype. Moreover, our finding may provide the first example that mexiletine exerts a dual rescue of both “gain-of-function” and “loss-of-function” of the mutant sodium channel.
Collapse
Affiliation(s)
- Rou-Mu Hu
- a Heart Center & Beijing Key Laboratory of Hypertension, Beijing Chaoyang Hospital , Capital Medical University , Beijing , China.,b Division of Cardiovascular Medicine, Department of Medicine , University of Wisconsin , Madison , Wisconsin , USA
| | - David J Tester
- c Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics , Mayo Clinic , Rochester , MN , USA
| | - Ryan Li
- d Departments of Pediatrics, and Cellular & Molecular Physiology , Pennsylvania State University College of Medicine , Hershey , PA , USA
| | - Tianyu Sun
- d Departments of Pediatrics, and Cellular & Molecular Physiology , Pennsylvania State University College of Medicine , Hershey , PA , USA
| | - Blaise Z Peterson
- d Departments of Pediatrics, and Cellular & Molecular Physiology , Pennsylvania State University College of Medicine , Hershey , PA , USA
| | - Michael J Ackerman
- c Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics , Mayo Clinic , Rochester , MN , USA
| | - Jonathan C Makielski
- b Division of Cardiovascular Medicine, Department of Medicine , University of Wisconsin , Madison , Wisconsin , USA
| | - Bi-Hua Tan
- b Division of Cardiovascular Medicine, Department of Medicine , University of Wisconsin , Madison , Wisconsin , USA.,d Departments of Pediatrics, and Cellular & Molecular Physiology , Pennsylvania State University College of Medicine , Hershey , PA , USA
| |
Collapse
|
9
|
Hayashi H, Sumiyoshi M, Nakazato Y, Daida H. Brugada syndrome and sinus node dysfunction. J Arrhythm 2018; 34:216-221. [PMID: 29951135 PMCID: PMC6009769 DOI: 10.1002/joa3.12046] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/12/2018] [Indexed: 12/19/2022] Open
Abstract
Brugada syndrome (BrS) is a well-known catastrophic disease first reported in 1992 by the Brugada brothers. Ventricular fibrillation (VF) is an essential arrhythmia in BrS. An association between BrS and atrial tachyarrhythmias is not uncommon. However, sinus node dysfunction (SND) associated with BrS has not been well discussed. In this review, we focus on the association between BrS and SND. Based on previous reports describing clinical, epidemiological, and genetic evidence, SND is not a rare concomitant disorder in BrS. BrS may be a multiple conduction or arrhythmogenic disorder including not only the His-Purkinje system and right ventricle, but also the sinus node and atrium, derived from ion channel mutations.
Collapse
Affiliation(s)
- Hidemori Hayashi
- Department of Cardiovascular MedicineJuntendo University School of MedicineTokyoJapan
| | | | - Yuji Nakazato
- Department of CardiologyJuntendo University Urayasu HospitalUrayasuJapan
| | - Hiroyuki Daida
- Department of Cardiovascular MedicineJuntendo University School of MedicineTokyoJapan
| |
Collapse
|
10
|
Sinus Bradycardia in Carriers of the SCN5A-1795insD Mutation: Unraveling the Mechanism through Computer Simulations. Int J Mol Sci 2018; 19:ijms19020634. [PMID: 29473904 PMCID: PMC5855856 DOI: 10.3390/ijms19020634] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 02/13/2018] [Accepted: 02/19/2018] [Indexed: 11/25/2022] Open
Abstract
The SCN5A gene encodes the pore-forming α-subunit of the ion channel that carries the cardiac fast sodium current (INa). The 1795insD mutation in SCN5A causes sinus bradycardia, with a mean heart rate of 70 beats/min in mutation carriers vs. 77 beats/min in non-carriers from the same family (lowest heart rate 41 vs. 47 beats/min). To unravel the underlying mechanism, we incorporated the mutation-induced changes in INa into a recently developed comprehensive computational model of a single human sinoatrial node cell (Fabbri–Severi model). The 1795insD mutation reduced the beating rate of the model cell from 74 to 69 beats/min (from 49 to 43 beats/min in the simulated presence of 20 nmol/L acetylcholine). The mutation-induced persistent INa per se resulted in a substantial increase in beating rate. This gain-of-function effect was almost completely counteracted by the loss-of-function effect of the reduction in INa conductance. The further loss-of-function effect of the shifts in steady-state activation and inactivation resulted in an overall loss-of-function effect of the 1795insD mutation. We conclude that the experimentally identified mutation-induced changes in INa can explain the clinically observed sinus bradycardia. Furthermore, we conclude that the Fabbri–Severi model may prove a useful tool in understanding cardiac pacemaker activity in humans.
Collapse
|
11
|
Vanninen SUM, Nikus K, Aalto-Setälä K. Electrocardiogram changes and atrial arrhythmias in individuals carrying sodium channel SCN5A D1275N mutation. Ann Med 2017; 49:496-503. [PMID: 28294644 DOI: 10.1080/07853890.2017.1307515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
INTRODUCTION The cardiac sodium channel SCN5A regulates atrioventricular and ventricular depolarization as well as cardiac conduction. Patients with cardiac electrical abnormalities have an increased risk of sudden cardiac death (SCD) and cardio-embolic stroke. Optimal management of cardiac disease includes the understanding of association between the causative mutations and the clinical phenotype. A 12-lead electrocardiogram (ECG) is an easy and inexpensive tool for finding risk patients. MATERIALS AND METHODS A blood sample for DNA extraction was obtained in a Finnish family with 43 members; systematic 12-lead ECG analysis was performed in 13 of the family members carrying an SCN5A D1275N mutation. Conduction defects and supraventricular arrhythmias, including atrial fibrillation/flutter, atrioventricular nodal re-entry tachycardia (AVNRT) and junctional rhythm were searched for. RESULTS Five (38%) mutation carriers had fascicular or bundle branch block, 10 had atrial arrhythmias; no ventricular arrhythmias were found. Notching of the R- and S waves - including initial QRS fragmentation - and prolonged S-wave upstroke were present in all the affected family members. Notably, four (31%) affected family members had a stroke before the age of 31 and two experienced premature death. CONCLUSIONS A 12-lead ECG can be used to predict arrhythmias in SCN5A D1275N mutation carriers. Key messages The 12-lead ECG may reveal cardiac abnormalities even before clinical symptoms occur. Specific ECG findings - initial QRS fragmentation, prolonged S-wave upstroke as well as supraventricular arrhythmias - were frequently encountered in all SCN5A D1257N mutation carriers. ECG follow-up is recommended for all SCN5A D1275N mutation carriers.
Collapse
Affiliation(s)
| | - Kjell Nikus
- a Heart Center, Tampere University Hospital , Tampere , Finland.,b Faculty of Medicine and Life Sciences , University of Tampere , Tampere , Finland
| | - Katriina Aalto-Setälä
- a Heart Center, Tampere University Hospital , Tampere , Finland.,b Faculty of Medicine and Life Sciences , University of Tampere , Tampere , Finland.,c BioMediTech, University of Tampere , Tampere , Finland
| |
Collapse
|
12
|
Jeevaratnam K, Guzadhur L, Goh YM, Grace AA, Huang CLH. Sodium channel haploinsufficiency and structural change in ventricular arrhythmogenesis. Acta Physiol (Oxf) 2016; 216:186-202. [PMID: 26284956 DOI: 10.1111/apha.12577] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 06/11/2015] [Accepted: 07/24/2015] [Indexed: 12/19/2022]
Abstract
Normal cardiac excitation involves orderly conduction of electrical activation and recovery dependent upon surface membrane, voltage-gated, sodium (Na(+) ) channel α-subunits (Nav 1.5). We summarize experimental studies of physiological and clinical consequences of loss-of-function Na(+) channel mutations. Of these conditions, Brugada syndrome (BrS) and progressive cardiac conduction defect (PCCD) are associated with sudden, often fatal, ventricular tachycardia (VT) or fibrillation. Mouse Scn5a(+/-) hearts replicate important clinical phenotypes modelling these human conditions. The arrhythmic phenotype is associated not only with the primary biophysical change but also with additional, anatomical abnormalities, in turn dependent upon age and sex, each themselves exerting arrhythmic effects. Available evidence suggests a unified binary scheme for the development of arrhythmia in both BrS and PCCD. Previous biophysical studies suggested that Nav 1.5 deficiency produces a background electrophysiological defect compromising conduction, thereby producing an arrhythmic substrate unmasked by flecainide or ajmaline challenge. More recent reports further suggest a progressive decline in conduction velocity and increase in its dispersion particularly in ageing male Nav 1.5 haploinsufficient compared to WT hearts. This appears to involve a selective appearance of slow conduction at the expense of rapidly conducting pathways with changes in their frequency distributions. These changes were related to increased cardiac fibrosis. It is thus the combination of the structural and biophysical changes both accentuating arrhythmic substrate that may produce arrhythmic tendency. This binary scheme explains the combined requirement for separate, biophysical and structural changes, particularly occurring in ageing Nav 1.5 haploinsufficient males in producing clinical arrhythmia.
Collapse
Affiliation(s)
- K. Jeevaratnam
- Faculty of Health and Medical Science; University of Surrey; Guilford UK
- Perdana University - Royal College of Surgeons Ireland; Serdang Selangor Darul Ehsan Malaysia
| | - L. Guzadhur
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
- Niche Science & Technology; Richmond UK
| | - Y. M. Goh
- Department of Preclinical Sciences; Faculty of Veterinary Medicine; University Putra Malaysia; Serdang Selangor Darul Ehsan Malaysia
| | - A. A. Grace
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
| | - C. L.-H. Huang
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
- Physiological Laboratory; University of Cambridge; Cambridge UK
| |
Collapse
|
13
|
Hothi SS, Ara F, Timperley J. p.Y1449C SCN5A mutation associated with overlap disorder comprising conduction disease, Brugada syndrome, and atrial flutter. J Cardiovasc Electrophysiol 2014; 26:93-7. [PMID: 24903439 DOI: 10.1111/jce.12470] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 05/16/2014] [Accepted: 05/28/2014] [Indexed: 11/27/2022]
Abstract
Mutations in the SCN5A gene, which encodes the cardiac sodium channel, have been associated with cardiac arrhythmia syndromes and conduction disease. Specific SCN5A mutations had initially been considered to cause specific phenotypes. More recently, some SCN5A mutations have been associated with overlap syndromes, characterized by phenotypic heterogeneity within and between mutation carriers. Here we report and associate the presence of the p.Y1449C SCN5A mutation in a single family with a spectrum of cardiac phenotypes including conduction disease, Brugada syndrome and atrial arrhythmias, for the first time to our knowledge.
Collapse
Affiliation(s)
- Sandeep S Hothi
- Physiological Laboratory, University of Cambridge, Cambridge, UK; Murray Edwards College, University of Cambridge, Cambridge, UK; Heart Centre, Northampton General Hospital, Northampton, UK
| | | | | |
Collapse
|
14
|
Affiliation(s)
- Naokata Sumitomo
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center
| |
Collapse
|
15
|
Nakaya H. SCN5A mutations associated with overlap phenotype of long QT syndrome type 3 and Brugada syndrome. Circ J 2014; 78:1061-2. [PMID: 24694743 DOI: 10.1253/circj.cj-14-0319] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Haruaki Nakaya
- Department of Pharmacology, Chiba University Graduate School of Medicine
| |
Collapse
|
16
|
Kawakami H, Aiba T, Yamada T, Okayama H, Kazatani Y, Konishi K, Nakajima I, Miyamoto K, Yamada Y, Okamura H, Noda T, Satomi K, Kamakura S, Makita N, Shimizu W. Variable phenotype expression with a frameshift mutation of the cardiac sodium channel gene SCN5A. J Arrhythm 2013. [DOI: 10.1016/j.joa.2013.04.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
17
|
Zumhagen S, Veldkamp MW, Stallmeyer B, Baartscheer A, Eckardt L, Paul M, Remme CA, Bhuiyan ZA, Bezzina CR, Schulze-Bahr E. A heterozygous deletion mutation in the cardiac sodium channel gene SCN5A with loss- and gain-of-function characteristics manifests as isolated conduction disease, without signs of Brugada or long QT syndrome. PLoS One 2013; 8:e67963. [PMID: 23840796 PMCID: PMC3695936 DOI: 10.1371/journal.pone.0067963] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 05/23/2013] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The SCN5A gene encodes for the α-subunit of the cardiac sodium channel NaV1.5, which is responsible for the rapid upstroke of the cardiac action potential. Mutations in this gene may lead to multiple life-threatening disorders of cardiac rhythm or are linked to structural cardiac defects. Here, we characterized a large family with a mutation in SCN5A presenting with an atrioventricular conduction disease and absence of Brugada syndrome. METHOD AND RESULTS In a large family with a high incidence of sudden cardiac deaths, a heterozygous SCN5A mutation (p.1493delK) with an autosomal dominant inheritance has been identified. Mutation carriers were devoid of any cardiac structural changes. Typical ECG findings were an increased P-wave duration, an AV-block I° and a prolonged QRS duration with an intraventricular conduction delay and no signs for Brugada syndrome. HEK293 cells transfected with 1493delK showed strongly (5-fold) reduced Na(+) currents with altered inactivation kinetics compared to wild-type channels. Immunocytochemical staining demonstrated strongly decreased expression of SCN5A 1493delK in the sarcolemma consistent with an intracellular trafficking defect and thereby a loss-of-function. In addition, SCN5A 1493delK channels that reached cell membrane showed gain-of-function aspects (slowing of the fast inactivation, reduction in the relative fraction of channels that fast inactivate, hastening of the recovery from inactivation). CONCLUSION In a large family, congregation of a heterozygous SCN5A gene mutation (p.1493delK) predisposes for conduction slowing without evidence for Brugada syndrome due to a predominantly trafficking defect that reduces Na(+) current and depolarization force.
Collapse
Affiliation(s)
- Sven Zumhagen
- Institute for Genetics of Heart Diseases, Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Song W, Xiao Y, Chen H, Ashpole NM, Piekarz AD, Ma P, Hudmon A, Cummins TR, Shou W. The human Nav1.5 F1486 deletion associated with long QT syndrome leads to impaired sodium channel inactivation and reduced lidocaine sensitivity. J Physiol 2012; 590:5123-39. [PMID: 22826127 DOI: 10.1113/jphysiol.2012.235374] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The deletion of phenylalanine 1486 (F1486del) in the human cardiac voltage-gated sodium channel (hNav1.5) is associated with fatal long QT (LQT) syndrome. In this study we determined how F1486del impairs the functional properties of hNav1.5 and alters action potential firing in heterologous expression systems (human embryonic kidney (HEK) 293 cells) and their native cardiomyocyte background. Cells expressing hNav1.5-F1486del exhibited a loss-of-function alteration, reflected by an 80% reduction of peak current density, and several gain-of-function alterations, including reduced channel inactivation, enlarged window current, substantial augmentation of persistent late sodium current and an increase in ramp current. We also observed substantial action potential duration (APD) prolongation and prominent early afterdepolarizations (EADs) in neonatal cardiomyocytes expressing the F1486del channels, as well as in computer simulations of myocyte activity. In addition, lidocaine sensitivity was dramatically reduced, which probably contributed to the poor therapeutic outcome observed in the patient carrying the hNav1.5-F1486del mutation. Therefore, despite the significant reduction in peak current density, the F1486del mutation also leads to substantial gain-of-function alterations that are sufficient to cause APD prolongation and EADs, the predominant characteristic of LQTs. These data demonstrate that hNav1.5 mutations can have complex functional consequences and highlight the importance of identifying the specific molecular defect when evaluating potential treatments for individuals with prolonged QT intervals.
Collapse
Affiliation(s)
- Weihua Song
- Riley Heart Research Center, Department of Pediatrics Herman B. Wells Center for Pediatric Research & Department of Pharmacology and Toxicology, Indiana University School of Medicine, 1044 W. Walnut Street, R4 W302D, Indianapolis, IN 46202, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Laurent G, Saal S, Amarouch MY, Béziau DM, Marsman RF, Faivre L, Barc J, Dina C, Bertaux G, Barthez O, Thauvin-Robinet C, Charron P, Fressart V, Maltret A, Villain E, Baron E, Mérot J, Turpault R, Coudière Y, Charpentier F, Schott JJ, Loussouarn G, Wilde AA, Wolf JE, Baró I, Kyndt F, Probst V. Multifocal Ectopic Purkinje-Related Premature Contractions. J Am Coll Cardiol 2012; 60:144-56. [DOI: 10.1016/j.jacc.2012.02.052] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 01/19/2012] [Accepted: 02/14/2012] [Indexed: 11/29/2022]
|
20
|
Concomitant Brugada-like and short QT electrocardiogram linked to SCN5A mutation. Eur J Hum Genet 2012; 20:1189-92. [PMID: 22490985 DOI: 10.1038/ejhg.2012.63] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Mutations in the α-subunit of cardiac sodium channel gene SCN5A can lead to the overlapping phenotypes of both the Brugada and type 3 long QT syndromes. However, the combination of Brugada and a short QT phenotype resulting from mutation in SCN5A has not previously been described. A man with concomitant Brugada-like and short QT electrocardiogram (ECG) was identified and the SCN5A gene was sequenced. Whole-cell patch clamp analysis of human embryo kidney (HEK) 293 cells expressing a SCN5A channel with the patient's sequence was used to investigate the biophysical properties of the channel. The patient with the family history of sudden death showed Brugada-like and short QT interval ECG. Sequence analysis of the coding region of the SCN5A gene, identified a G to A heterozygous missense mutation at nucleotide site 2066 that resulted in a amino-acid substitution of arginine to histidine at amino-acid site 689 (R689H). Patch clamp analysis showed that the R689H failed to generate current when heterologously expressed in HEK293 cells, indicating it was a loss-of-function mutation. Our finding firstly shows that a heterozygous missense mutation R689H in SCN5A gene results in the loss of protein function and the coexistents of the Brugada-like and short QT interval ECG phenotypes.
Collapse
|
21
|
Wu J, Zhang Y, Zhang X, Cheng L, Lammers WJ, Grace AA, Fraser JA, Zhang H, Huang CLH, Lei M. Altered sinoatrial node function and intra-atrial conduction in murine gain-of-function Scn5a+/ΔKPQ hearts suggest an overlap syndrome. Am J Physiol Heart Circ Physiol 2012; 302:H1510-23. [PMID: 22287583 PMCID: PMC3330789 DOI: 10.1152/ajpheart.00357.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mutations in SCN5A, the gene encoding the pore-forming subunit of cardiac Na+ channels, cause a spectrum of arrhythmic syndromes. Of these, sinoatrial node (SAN) dysfunction occurs in patients with both loss- and gain-of-function SCN5A mutations. We explored for corresponding alterations in SAN function and intracardiac conduction and clarified possible mechanisms underlying these in an established mouse long QT syndrome type 3 model carrying a mutation equivalent to human SCN5A-ΔKPQ. Electrophysiological characterizations of SAN function in living animals and in vitro sinoatrial preparations were compared with cellular SAN and two-dimensional tissue models exploring the consequences of Scn5a+/ΔKPQ mutations. Scn5a+/ΔKPQ mice showed prolonged electrocardiographic QT and corrected QT intervals confirming long QT phenotypes. They showed frequent episodes of sinus bradycardia, sinus pause/arrest, and significantly longer sinus node recovery times, suggesting compromised pacemaker activity compared with wild-type mice. Electrocardiographic waveforms suggested depressed intra-atrial, atrioventricular node, and intraventricular conduction in Scn5a+/ΔKPQ mice. Isolated Scn5a+/ΔKPQ sinoatrial preparations similarly showed lower mean intrinsic heart rates and overall slower conduction through the SAN to the surrounding atrium than did wild-type preparations. Computer simulations of both single SAN cells as well as two-dimensional SAN-atrial models could reproduce the experimental observations of impaired pacemaker and sinoatrial conduction in terms of changes produced by both augmented tail and reduced total Na+ currents, respectively. In conclusion, the gain-of-function long QT syndrome type 3 murine Scn5a+/ΔKPQ cardiac system, in overlap with corresponding features reported in loss-of-function Na+ channel mutations, shows compromised SAN pacemaker and conduction function explicable in modeling studies through a combination of augmented tail and reduced peak Na+ currents.
Collapse
Affiliation(s)
- Jingjing Wu
- Department of Cardiovascular Diseases, Union Hospital, Huazhong University of Sciences and Technology, Wuhan, Peoples' Republic of China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Shinlapawittayatorn K, Dudash LA, Du XX, Heller L, Poelzing S, Ficker E, Deschênes I. A novel strategy using cardiac sodium channel polymorphic fragments to rescue trafficking-deficient SCN5A mutations. ACTA ACUST UNITED AC 2011; 4:500-9. [PMID: 21840964 DOI: 10.1161/circgenetics.111.960633] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Brugada syndrome (BrS) is associated with mutations in the cardiac sodium channel (Na(v)1.5). We previously reported that the function of a trafficking-deficient BrS Na(v)1.5 mutation, R282H, could be restored by coexpression with the sodium channel polymorphism H558R. Here, we tested the hypothesis that peptide fragments from Na(v)1.5, spanning the H558R polymorphism, can be used to restore trafficking of trafficking-deficient BrS sodium channel mutations. METHODS AND RESULTS Whole-cell patch clamping revealed that cotransfection in human embryonic kidney (HEK293) cells of the R282H channel with either the 40- or 20-amino acid cDNA fragments of Na(v)1.5 containing the H558R polymorphism restored trafficking of this mutant channel. Fluorescence resonance energy transfer suggested that the trafficking-deficient R282H channel was misfolded, and this was corrected on coexpression with R558-containing peptides that restored trafficking of the R282H channel. Importantly, we also expressed the peptide spanning the H558R polymorphism with 8 additional BrS Na(v)1.5 mutations with reduced currents and demonstrated that the peptide was able to restore significant sodium currents in 4 of them. CONCLUSIONS In the present study, we demonstrate that small peptides, spanning the H558R polymorphism, are sufficient to restore the trafficking defect of BrS-associated Na(v)1.5 mutations. Our findings suggest that it might be possible to use short cDNA constructs as a novel strategy tailored to specific disease-causing mutants of BrS.
Collapse
Affiliation(s)
- Krekwit Shinlapawittayatorn
- Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, OH 44109, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
Capulzini L, Brugada P, Brugada J, Brugada R. Arrhythmia and right heart disease: from genetic basis to clinical practice. Rev Esp Cardiol 2011; 63:963-83. [PMID: 20738941 DOI: 10.1016/s1885-5857(10)70190-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Historically, left ventricular cardiomyopathy and coronary heart disease have been regarded as the main causes of ventricular arrhythmia and sudden cardiac death. However, within last two decades, arrhythmias originating from the right ventricle have begun to attract the attention of the scientific world for a number of reasons. Ventricular arrhythmias originating from the right ventricle usually affect younger patients and can lead to sudden cardiac death. The pathophysiologic mechanism of these arrhythmias is not fully understood, which can leave room for a range of different interpretations. Moreover, the intriguing world of genetics is increasingly being drawn into the pathogenesis, diagnosis and prognosis of some of these arrhythmias. This review considers the pathogenesis, diagnosis and treatment of arrhythmogenic right ventricular cardiomyopathy or dysplasia (ARVD), Brugada syndrome, right ventricular outflow tract ventricular tachycardia, and arrhythmias in the right side of the heart due to congenital heart disease. In addition, because ventricular arrhythmias associated with right ventricular heart diseases such as Brugada syndrome and ARVD can explain up to 10-30% of sudden cardiac deaths in young adults in the general population and an even greater percentage in young athletes, this article contains a brief analysis of screening tests used before participation in sports, life-style modification, and treatment options for athletes affected by these conduction disorders.
Collapse
Affiliation(s)
- Lucio Capulzini
- Heart Rhythm Management Centre, UZ-Brussels-VUB, Bruselas, Bélgica.
| | | | | | | |
Collapse
|
24
|
Nakajima T, Kaneko Y, Saito A, Irie T, Tange S, Iso T, Kurabayashi M. Identification of Six Novel SCN5A Mutations in Japanese Patients With Brugada Syndrome. Int Heart J 2011; 52:27-31. [DOI: 10.1536/ihj.52.27] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Tadashi Nakajima
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine
| | - Yoshiaki Kaneko
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine
| | - Akihiro Saito
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine
| | - Tadanobu Irie
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine
| | - Shoichi Tange
- Cardiovascular Department, Maebashi Red Cross Hospital
| | - Tatsuya Iso
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine
| | - Masahiko Kurabayashi
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine
| |
Collapse
|
25
|
Oka Y, Itoh H, Ding WG, Shimizu W, Makiyama T, Ohno S, Nishio Y, Sakaguchi T, Miyamoto A, Kawamura M, Matsuura H, Horie M. Atrioventricular block-induced Torsades de Pointes with clinical and molecular backgrounds similar to congenital long QT syndrome. Circ J 2010; 74:2562-71. [PMID: 20975234 DOI: 10.1253/circj.cj-10-0498] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Atrioventricular block (AVB) sometimes complicates QT prolongation and torsades de pointes (TdP). METHODS AND RESULTS The clinical and genetic background of 14 AVB patients (57±21 years, 13 females) who developed QT prolongation and TdP was analyzed. Electrophysiological characteristics of mutations were analyzed using heterologous expression in Chinese hamster ovary cells, together with computer simulation models. Every patient received a pacemaker or implantable cardioverter defibrillator; 3 patients had recurrence of TdP during follow-up because of pacing failure. Among the ECG parameters, QTc interval was prolonged to 561±76ms in the presence of AVB, but shortened to 495±42ms in the absence of AVB. Genetic screening for KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 revealed four heterozygous missense mutations of KCNQ1 or KCNH2 in 4 patients (28.6%). Functional analyses showed that all mutations had loss of functions and various gating dysfunctions of I(Ks) or I(Kr). Finally, action potential simulation based on the Luo-Rudy model demonstrated that most mutant channels induced bradycardia-related early afterdepolarizations. CONCLUSIONS Incidental AVB, as a trigger of TdP, can manifest as clinical phenotypes of long QT syndrome (LQTS), and that some patients with AVB-induced TdP share a genetic background with those with congenital LQTS.
Collapse
Affiliation(s)
- Yuko Oka
- Department of Respiratory and Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Capulzini L, Brugada P, Brugada J, Brugada R. Arritmias y enfermedades del corazón derecho: de las bases genéticas a la clínica. Rev Esp Cardiol 2010. [DOI: 10.1016/s0300-8932(10)70208-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
27
|
Amin AS, Asghari-Roodsari A, Tan HL. Cardiac sodium channelopathies. Pflugers Arch 2010; 460:223-37. [PMID: 20091048 PMCID: PMC2883928 DOI: 10.1007/s00424-009-0761-0] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 11/09/2009] [Accepted: 11/11/2009] [Indexed: 02/06/2023]
Abstract
Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (INa) during phase 0 of the cardiac action potential. The importance of INa for normal cardiac electrical activity is reflected by the high incidence of arrhythmias in cardiac sodium channelopathies, i.e., arrhythmogenic diseases in patients with mutations in SCN5A, the gene responsible for the pore-forming ion-conducting alpha-subunit, or in genes that encode the ancillary beta-subunits or regulatory proteins of the cardiac sodium channel. While clinical and genetic studies have laid the foundation for our understanding of cardiac sodium channelopathies by establishing links between arrhythmogenic diseases and mutations in genes that encode various subunits of the cardiac sodium channel, biophysical studies (particularly in heterologous expression systems and transgenic mouse models) have provided insights into the mechanisms by which INa dysfunction causes disease in such channelopathies. It is now recognized that mutations that increase INa delay cardiac repolarization, prolong action potential duration, and cause long QT syndrome, while mutations that reduce INa decrease cardiac excitability, reduce electrical conduction velocity, and induce Brugada syndrome, progressive cardiac conduction disease, sick sinus syndrome, or combinations thereof. Recently, mutation-induced INa dysfunction was also linked to dilated cardiomyopathy, atrial fibrillation, and sudden infant death syndrome. This review describes the structure and function of the cardiac sodium channel and its various subunits, summarizes major cardiac sodium channelopathies and the current knowledge concerning their genetic background and underlying molecular mechanisms, and discusses recent advances in the discovery of mutation-specific therapies in the management of these channelopathies.
Collapse
Affiliation(s)
- Ahmad S. Amin
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Alaleh Asghari-Roodsari
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Hanno L. Tan
- Department of Cardiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Room K2-109, Meibergdreef 9, Amsterdam, 1105 AZ the Netherlands
| |
Collapse
|
28
|
Manace LC, Godiwala TN, Babyatsky MW. Genomics of cardiovascular disease. ACTA ACUST UNITED AC 2010; 76:613-23. [PMID: 20014425 DOI: 10.1002/msj.20151] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
As the leading cause of death worldwide and a major cause of disability, cardiovascular disease remains a central focus of basic research, pharmacological treatment, surgical interventions, and long-term care. Inherited, monogenic syndromes have provided insight into pathophysiological mechanisms across the range of cardiovascular diseases. With the advent of post-Human Genome Project resources and technology, there has been a flood of research aimed at genome-wide predisposition markers, pharmacogenetics, and genomic signatures in complex cardiovascular disorders. Genomic research has both further elucidated the impact of genes previously identified in cardiovascular disease development and progression and discovered genomic regions as yet unknown to be associated with cardiovascular outcomes. The promise of personalized medicine lies in combining this genetic information with other biomarkers to tailor preventive and therapeutic strategies to individual patients for effective management, fewer adverse events, and preventive care.
Collapse
Affiliation(s)
- Leslie Cole Manace
- Department of Genetics, Kaiser Oakland Medical Center, Oakland, CA, USA.
| | | | | |
Collapse
|
29
|
Nishizaki M, Sakurada H, Yamawake N, Ueda-Tatsumoto A, Hiraoka M. Low Risk for Arrhythmic Events in Asymptomatic Patients With Drug-Induced Type 1 ECG. Circ J 2010; 74:2464-73. [DOI: 10.1253/circj.cj-10-0878] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
30
|
Hayashi H, Sumiyoshi M, Yasuda M, Komatsu K, Sekita G, Kawano Y, Tokano T, Nakazato Y, Daida H. Prevalence of the Brugada-Type Electrocardiogram and Incidence of Brugada Syndrome in Patients With Sick Sinus Syndrome. Circ J 2010; 74:271-7. [DOI: 10.1253/circj.cj-09-0455] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Hidemori Hayashi
- Department of Cardiology, Juntendo University School of Medicine
| | | | - Masayuki Yasuda
- Department of Cardiology, Juntendo University School of Medicine
| | - Kaoru Komatsu
- Department of Cardiology, Juntendo University School of Medicine
| | - Gaku Sekita
- Department of Cardiology, Juntendo University School of Medicine
| | - Yasunobu Kawano
- Department of Cardiology, Juntendo University Urayasu Hospital
| | - Takashi Tokano
- Department of Cardiology, Juntendo University Shizuoka Hospital
| | - Yuji Nakazato
- Department of Cardiology, Juntendo University Urayasu Hospital
| | - Hiroyuki Daida
- Department of Cardiology, Juntendo University School of Medicine
| |
Collapse
|
31
|
Fowler SJ, Napolitano C, Priori SG. The genetics of cardiomyopathy: Genotyping and genetic counseling. CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2009; 11:433-46. [DOI: 10.1007/s11936-009-0046-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|