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Krijger Juárez C, Amin AS, Offerhaus JA, Bezzina CR, Boukens BJ. Cardiac Repolarization in Health and Disease. JACC Clin Electrophysiol 2023; 9:124-138. [PMID: 36697193 DOI: 10.1016/j.jacep.2022.09.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 09/16/2022] [Accepted: 09/21/2022] [Indexed: 12/03/2022]
Abstract
Abnormal cardiac repolarization is at the basis of life-threatening arrhythmias in various congenital and acquired cardiac diseases. Dysfunction of ion channels involved in repolarization at the cellular level are often the underlying cause of the repolarization abnormality. The expression pattern of the gene encoding the affected ion channel dictates its impact on the shape of the T-wave and duration of the QT interval, thereby setting the stage for both the occurrence of the trigger and the substrate for maintenance of the arrhythmia. Here we discuss how research into the genetic and electrophysiological basis of repolarization has provided us with insights into cardiac repolarization in health and disease and how this in turn may provide the basis for future improved patient-specific management.
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Affiliation(s)
- Christian Krijger Juárez
- Department of Experimental Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Ahmad S Amin
- Department of Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Joost A Offerhaus
- Department of Experimental Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Connie R Bezzina
- Department of Experimental Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Bastiaan J Boukens
- Department of Medical Biology, Amsterdam University Medical Center, Amsterdam, the Netherlands; Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands.
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Affiliation(s)
- Arie O Verkerk
- Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Carol Ann Remme
- Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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Inherited primary arrhythmia disorders: cardiac channelopathies and sports activity. Herz 2018; 45:142-157. [PMID: 29744527 DOI: 10.1007/s00059-018-4706-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 03/25/2018] [Accepted: 04/14/2018] [Indexed: 01/02/2023]
Abstract
Sudden cardiac death (SCD) in an apparently healthy individual is a tragedy. It is important to identify the cause of death and to prevent SCD in potentially at-risk family members. Inherited primary arrhythmia disorders are associated with exercise-related SCD. Despite the well-known benefits of exercise, exercise restriction has been a historical mainstay of therapy for these conditions. However, since familiarity with inherited arrhythmia conditions has increased and patients are often children and young adults, it is necessary to reassess the treatment guidelines regarding exercise constraints. The aim of this review is to analyze the risk of exercise-induced SCD in patients with inherited cardiac conditions and explore the challenges faced when advising patients about exercise limitations. We searched for publications on cardiac channelopathies in PubMed with the following medical subject headings (MeSH): "long QT syndrome"; "short QT syndrome"; "Brugada syndrome"; and "catecholaminergic polymorphic ventricular tachycardia". The abstracts of these articles were scanned, and articles of relevance, along with pertinent references, were read in full. The analysis was restricted to reports published in English. The findings of this analysis suggest that exercise with low-to-moderate cardiovascular demand may be possible under regular clinical follow-up in inherited primary arrhythmia disorders. Recent data show that patients with inherited primary arrhythmia disorders are at low risk for events once a comprehensive treatment program has been established. Recreational activity is likely safe for these individuals, with personalized management based on individual patient preferences and priorities.
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Hancox JC, Whittaker DG, Du C, Stuart AG, Zhang H. Emerging therapeutic targets in the short QT syndrome. Expert Opin Ther Targets 2018; 22:439-451. [DOI: 10.1080/14728222.2018.1470621] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Jules C Hancox
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University Walk, Bristol, United Kingdom
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
| | - Dominic G Whittaker
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Chunyun Du
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University Walk, Bristol, United Kingdom
| | - A. Graham Stuart
- Cardiology, Bristol Heart Institute, University of Bristol, Bristol, United Kingdom
| | - Henggui Zhang
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
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Lee HC, Rudy Y, Liang H, Chen CC, Luo CH, Sheu SH, Cui J. Pro-arrhythmogenic Effects of the V141M KCNQ1 Mutation in Short QT Syndrome and Its Potential Therapeutic Targets: Insights from Modeling. J Med Biol Eng 2017; 37:780-789. [PMID: 29213224 PMCID: PMC5714284 DOI: 10.1007/s40846-017-0257-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Gain-of-function mutations in the pore-forming subunit of IKs channels, KCNQ1, lead to short QT syndrome (SQTS) and lethal arrhythmias. However, how mutant IKs channels cause SQTS and the possibility of IKs-specific pharmacological treatment remain unclear. V141M KCNQ1 is a SQTS associated mutation. We studied its effect on IKs gating properties and changes in the action potentials (AP) of human ventricular myocytes. Xenopus oocytes were used to study the gating mechanisms of expressed V141M KCNQ1/KCNE1 channels. Computational models were used to simulate human APs in endocardial, mid-myocardial, and epicardial ventricular myocytes with and without β-adrenergic stimulation. V141M KCNQ1 caused a gain-of-function in IKs characterized by increased current density, faster activation, and slower deactivation leading to IKs accumulation. V141M KCNQ1 also caused a leftward shift of the conductance-voltage curve compared to wild type (WT) IKs (V1/2 = 33.6 ± 4.0 mV for WT, and 24.0 ± 1.3 mV for heterozygous V141M). A Markov model of heterozygous V141M mutant IKs was developed and incorporated into the O’Hara–Rudy model. Compared to the WT, AP simulations demonstrated marked rate-dependent shortening of AP duration (APD) for V141M, predicting a SQTS phenotype. Transmural electrical heterogeneity was enhanced in heterozygous V141M AP simulations, especially under β-adrenergic stimulation. Computational simulations identified specific IK1 blockade as a beneficial pharmacologic target for reducing the transmural APD heterogeneity associated with V141M KCNQ1 mutation. V141M KCNQ1 mutation shortens ventricular APs and enhances transmural APD heterogeneity under β-adrenergic stimulation. Computational simulations identified IK1 blockers as a potential antiarrhythmic drug of choice for SQTS.
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Affiliation(s)
- Hsiang-Chun Lee
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO 63130, USA.,Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, 100 Tzyou 1st Rd, Kaohsiung 807, Taiwan.,Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.,Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan.,Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.,Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung 804, Taiwan
| | - Yoram Rudy
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Hongwu Liang
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Chih-Chieh Chen
- Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung 804, Taiwan
| | - Ching-Hsing Luo
- Department of Electric Engineering, National Cheng Kung University, Tainan 804, Taiwan
| | - Sheng-Hsiung Sheu
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, 100 Tzyou 1st Rd, Kaohsiung 807, Taiwan.,Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.,Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Jianmin Cui
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO 63130, USA
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Zumhagen S, Zeidler EM, Stallmeyer B, Ernsting M, Eckardt L, Schulze-Bahr E. Tpeak-Tend interval and Tpeak-Tend/QT ratio in patients with Brugada syndrome. Europace 2016; 18:1866-1872. [PMID: 26941339 DOI: 10.1093/europace/euw033] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 02/02/2016] [Indexed: 01/11/2023] Open
Abstract
AIMS Brugada syndrome (BrS) is characterized by a typical electrocardiogram (ECG) pattern in right precordial leads (V1-V3; so-called type 1 ECG) and an increased risk of sudden cardiac death due to ventricular fibrillation. Annual cardiac event rates vary from 0.5% in asymptomatic to 7.7% in high-risk patients. So far, spontaneous occurrence of the type 1 ECG, survived cardiac arrest, and/or documented ventricular arrhythmias are main risk predictors, whereas other factors (e.g. family history or genotype) are not applicable for risk stratification. In this study, we investigated the relationship between Tpeak-Tend intervals (TpTe) as a novel ECG parameter for the occurrence of cardiac arrhythmias. METHODS AND RESULTS Clinical and genetic data of 78 unrelated BrS patients (male: n = 57, age: 45 ± 14 years) were retrospectively analysed for medical history, gene mutation, and ECG parameters (in particular heart rate, PQ, QRS, QT, and TpTe) as obtained after digital measurements. TpTe in ECG lead V1 (87 ± 30 vs. 71 ± 27 ms; P = 0.017) and the TpTe/QT ratio (0.24 vs. 0.19; P = 0.018) were significantly higher in high-risk BrS patients than in other BrS patients. In the other right precordial leads typically indicative for BrS, no significant difference was noted. CONCLUSION Assessment of the TpTe interval or the TpTe/QT ratio in lead V1 is potentially useful as a non-invasive risk marker for BrS patients with life-threatening arrhythmias.
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Affiliation(s)
- Sven Zumhagen
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Albert-Schweitzer-Campus 1, Gebäude D3, D-48149 Münster, Germany .,Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Eva Maria Zeidler
- Department of Anaesthesiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Birgit Stallmeyer
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Albert-Schweitzer-Campus 1, Gebäude D3, D-48149 Münster, Germany
| | - Marko Ernsting
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Albert-Schweitzer-Campus 1, Gebäude D3, D-48149 Münster, Germany
| | - Lars Eckardt
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Eric Schulze-Bahr
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Albert-Schweitzer-Campus 1, Gebäude D3, D-48149 Münster, Germany.,Interdisciplinary Centre for Clinical Research (IZKF), University Hospital Münster, Münster, Germany
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Castro-Torres Y, Carmona-Puerta R, Katholi RE. Ventricular repolarization markers for predicting malignant arrhythmias in clinical practice. World J Clin Cases 2015; 3:705-720. [PMID: 26301231 PMCID: PMC4539410 DOI: 10.12998/wjcc.v3.i8.705] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 02/22/2015] [Accepted: 06/08/2015] [Indexed: 02/05/2023] Open
Abstract
Malignant cardiac arrhythmias which result in sudden cardiac death may be present in individuals apparently healthy or be associated with other medical conditions. The way to predict their appearance represents a challenge for the medical community due to the tragic outcomes in most cases. In the last two decades some ventricular repolarization (VR) markers have been found to be useful to predict malignant cardiac arrhythmias in several clinical conditions. The corrected QT, QT dispersion, Tpeak-Tend, Tpeak-Tend dispersion and Tp-e/QT have been studied and implemented in clinical practice for this purpose. These markers are obtained from 12 lead surface electrocardiogram. In this review we discuss how these markers have demonstrated to be effective to predict malignant arrhythmias in medical conditions such as long and short QT syndromes, Brugada syndrome, early repolarization syndrome, acute myocardial ischemia, heart failure, hypertension, diabetes mellitus, obesity and highly trained athletes. Also the main pathophysiological mechanisms that explain the arrhythmogenic predisposition in these diseases and the basis for the VR markers are discussed. However, the same results have not been found in all conditions. Further studies are needed to reach a global consensus in order to incorporate these VR parameters in risk stratification of these patients.
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Sonoda K, Watanabe H, Hisamatsu T, Ashihara T, Ohno S, Hayashi H, Horie M, Minamino T. High Frequency of Early Repolarization and Brugada-Type Electrocardiograms in Hypercalcemia. Ann Noninvasive Electrocardiol 2015; 21:30-40. [PMID: 26263049 DOI: 10.1111/anec.12303] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 06/26/2015] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND J wave, or early repolarization has recently been associated with an increased risk of lethal arrhythmia and sudden death, both in idiopathic ventricular fibrillation and in the general population. Hypercalcemia is one of the causes of J point and ST segment elevation, but the relationship has not been well studied. The aim of this study was to examine the effects of hypercalcemia on J point elevation. METHODS Electrocardiographic findings were compared in 89 patients with hypercalcemia and 267 age- and sex-matched healthy controls with normocalcemia. The association of J point elevation with arrhythmia events in patients with hypercalcemia was also studied. RESULTS The PR interval and the QRS duration were longer in patients with hypercalcemia than in normocalcemic controls. Both the QT and the corrected QT intervals were shorter in patients with hypercalcemia compared with normocalcemic controls. Conduction disorders, ST-T abnormalities, and J point elevation were more common in patients with hypercalcemia than normocalcemic controls. Following the resolution of hypercalcemia, the frequency of J point elevation decreased to a level similar to that noted in controls. During hospitalization, no arrhythmia event occurred in patients with hypercalcemia. CONCLUSION Hypercalcemia was associated with J point elevation.
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Affiliation(s)
- Keiko Sonoda
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Watanabe
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Takashi Hisamatsu
- Center for Epidemiologic Research in Asia, Shiga University of Medical Science, Otsu, Japan.,Department of Public Health, Shiga University of Medical Science, Otsu, Japan.,Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Takashi Ashihara
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Seiko Ohno
- Center for Epidemiologic Research in Asia, Shiga University of Medical Science, Otsu, Japan.,Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Hideki Hayashi
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Tohru Minamino
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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Abstract
BACKGROUND Risk stratification in Brugada syndrome (BS) remains controversial. The time interval between the peak and the end of the T wave (Tpe interval), a marker of transmural dispersion of repolarization, has been linked to malignant ventricular arrhythmias in various settings but leads to discordant results in BS. OBJECTIVE We study the correlation of the Tpe interval with arrhythmic events in a large cohort of patients with BS. METHODS A total of 325 consecutive patients with BS (mean age 47±13 years, 259 men-80%) with spontaneous (n=143, 44%) or drug-induced (n=182, 56%) type 1 electrocardiogram were retrospectively included. 235 were asymptomatic (70%), 80 presented with unexplained syncope (22%), and 10 presented with sudden death (SD) or appropriate implantable cardioverter-defibrillator therapy (AT) (8%) at diagnosis or over a mean follow-up of 48 ± 34 months. The Tpe interval was calculated as the difference between the QT interval and the QT peak interval as measured in each of the precordial leads. RESULTS The Tpe interval from lead V1 to lead V4, maximum value of the Tpe interval (max Tpe), and Tpe dispersion in all precordial leads were significantly higher in patients with SD/AT or in patients with syncope than in asymptomatic patients (P < .001). A max Tpe of ≥100 ms was present in 47 of 226 asymptomatic patients (21%), in 48 of 73 patients with syncope (66%), and in 22 of 26 patients with SD/AT (85%) (P < .0001). In multivariate analysis, a max Tpe of ≥100 ms was independently related to arrhythmic events (odds ratio 9.61; 95% confidence interval 3.13-29.41; P < .0001). CONCLUSION The Tpe interval in the precordial leads is highly related to malignant ventricular arrhythmias in this large cohort of patients with BS. This simple electrocardiographic parameter could be used to refine risk stratification.
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Obeyesekere MN, Antzelevitch C, Krahn AD. Management of ventricular arrhythmias in suspected channelopathies. Circ Arrhythm Electrophysiol 2015; 8:221-31. [PMID: 25691556 DOI: 10.1161/circep.114.002321] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Manoj N Obeyesekere
- From the Department of Cardiology, Northern Healthcare Group, Epping, Victoria, Australia (M.N.O.); Masonic Medical Research Laboratory, Utica, NY (C.A.); and Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.).
| | - Charles Antzelevitch
- From the Department of Cardiology, Northern Healthcare Group, Epping, Victoria, Australia (M.N.O.); Masonic Medical Research Laboratory, Utica, NY (C.A.); and Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.)
| | - Andrew D Krahn
- From the Department of Cardiology, Northern Healthcare Group, Epping, Victoria, Australia (M.N.O.); Masonic Medical Research Laboratory, Utica, NY (C.A.); and Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada (A.D.K.)
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Ni M, Ruan L, Zhang C. Antiarrhythmic Peptide AAP10 Prevents Arrhythmias Induced by Protein Kinase C Activation in Rabbit Left Ventricular Wedges. Int Heart J 2015; 56:234-8. [DOI: 10.1536/ihj.14-234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Mingke Ni
- Department of Cardiology, Zhongshan Hospital
| | - Lei Ruan
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology
| | - Cuntai Zhang
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology
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Suzuki H, Hoshina S, Ozawa J, Sato A, Minamino T, Aizawa Y, Saitoh A. Short QT syndrome in a boy diagnosed on screening for heart disease. Pediatr Int 2014; 56:774-6. [PMID: 25335996 PMCID: PMC4241042 DOI: 10.1111/ped.12308] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 01/23/2014] [Indexed: 11/30/2022]
Abstract
We report on an asymptomatic 10-year-old boy who had a short QT interval (corrected QT interval, 260 ms). Short QT syndrome (SQTS) was detected in a school screening program for heart disease and the patient was subsequently diagnosed as having N588K mutation in the KCNH2 gene. Quinidine prolonged the QT interval, but not the QU interval. During treadmill exercise stress test, QT and QU intervals responded differently to heart rate changes, suggesting a mechanoelectrical hypothesis for the origin of the U wave. Although rare, attention should be paid to SQTS, which is associated with potential fatal arrhythmias.
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Affiliation(s)
- Hiroshi Suzuki
- Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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Choudhuri I, Pinninti M, Marwali MR, Sra J, Akhtar M. Polymorphic ventricular tachycardia--part II: the channelopathies. Curr Probl Cardiol 2014; 38:503-48. [PMID: 24262155 DOI: 10.1016/j.cpcardiol.2013.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this article, we explore the clinical and cellular phenomena of primary electrical diseases of the heart, that is, conditions purely related to ion channel dysfunction and not structural heart disease or reversible acquired causes. This growing classification of conditions, once considered together as "idiopathic ventricular fibrillation," continues to evolve and segregate into diseases that are phenotypically, molecularly, and genetically unique.
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Ruan L, Quan X, Li L, Bai R, Ni M, Xu R, Zhang C. Increasing gap junction coupling suppresses ibutilide-induced torsades de pointes. Exp Ther Med 2014; 7:1279-1284. [PMID: 24940425 PMCID: PMC3991525 DOI: 10.3892/etm.2014.1601] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 02/13/2014] [Indexed: 11/24/2022] Open
Abstract
Drug-induced torsades de pointes (TdP) is common with class III antiarrhythmic drugs. Increased transmural dispersion of repolarization (TDR) contributes significantly to the development of TdP. Gap junctions play an important role in maintaining TDR in long QT syndrome. The present study examined the effect of a gap junction enhancer, antiarrhythmic peptide 10 (AAP10), on ibutilide-induced TdP. Coronary-perfused rabbit ventricular wedge preparations were used to evaluate the effect of AAP10 on ibutilide-induced arrhythmia. Transmural electrocardiograms and action potentials were recorded simultaneously. Early afterdepolarizations (EADs), R-on-T extrasystole, TdP and changes in Tpeak-end (Tp-e) and the Tp-e/QT ratio were observed. Changes in the levels of non-phosphorylated connexin 43 (Cx43) were measured by immunoblotting. Compared with those in the control group, the QT interval, Tp-e/QT and incidence rates of EAD and TdP increased with augmented dephosphorylation in the ventricular wedge preparations perfused with ibutilide under conditions of hypokalemia and hypomagnesemia. In the presence of AAP10, the incidence rates of EAD and TdP were reduced and the Tp-e/QT ratio decreased, with a parallel reduction in the level of non-phosphorylated Cx43. The results indicate that AAP10 suppressed ibutilide-induced TdP under conditions of hypokalemia and hypomagnesemia by decreasing TDR. AAP10 reduced TDR, possibly by preventing the dephosphorylation of Cx43 and thereby increasing myocardial cell gap junction coupling.
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Affiliation(s)
- Lei Ruan
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Xiaoqing Quan
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Liandong Li
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Rong Bai
- Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, P.R. China
| | - Mingke Ni
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Rende Xu
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Cuntai Zhang
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
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Lu HR, Yan GX, Gallacher DJ. A new biomarker--index of cardiac electrophysiological balance (iCEB)--plays an important role in drug-induced cardiac arrhythmias: beyond QT-prolongation and Torsades de Pointes (TdPs). J Pharmacol Toxicol Methods 2013; 68:250-259. [PMID: 23337247 DOI: 10.1016/j.vascn.2013.01.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 01/02/2013] [Accepted: 01/05/2013] [Indexed: 12/15/2022]
Abstract
INTRODUCTION In the present study, we investigated whether a new biomarker - index of cardiac electrophysiological balance (iCEB=QT/QRS) - could predict drug-induced cardiac arrhythmias (CAs), including ventricular tachycardia/ventricular fibrillation (VT/VF) and Torsades de Pointes (TdPs). METHODS The rabbit left ventricular arterially-perfused-wedge was used to investigate whether the simple iCEB measured from the ECG is reflective of the more difficult measurement of λ (effective refractory period×conduction velocity) for predicting CAs induced by a number of drugs. RESULTS Dofetilide concentration-dependently increased iCEB and λ, predicting potential risk of drug-induced incidence of early afterdepolarizations (EADs) starting at 0.01μM. Digoxin (1 and 5μM), encainide (5 and 20μM) and propoxyphene (10 and 100μM) markedly reduced both iCEB and λ, predicting their ability to induce non-TdP-like VT/VF. At 10μM, both NS1643 and levcromakalim significantly decreased λ and iCEB, which was preceded with presence of non-TdP-like VT/VF. Isoprenaline (0.05 to 0.5μM) significantly reduced both λ and iCEB, which was associated with a high incidence of non-TdP-like VT/VF in most preparations. Other biomarkers (i.e. transmural dispersion of T-wave and instability of the QT interval) predicted only dofetilide-induced long QT and EADs, but did not predict drug-induced risk of non-TdP-like VT/VF. DISCUSSION Our data from 7 reference drugs of known pro-arrhythmic effects suggests that 1) this non-invasive iCEB predicts potential risk of drug-induced CAs beyond long QT and TdP; 2) iCEB is more useful than the current biomarkers (i.e. transmural dispersion and instability) in predicting potential risks for drug-induced non-TdP-like VT/VF.
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Affiliation(s)
- Hua Rong Lu
- Janssen Research and Development, Janssen Pharmaceutica NV, Belgium.
| | - Gan-Xin Yan
- Main Line Health Heart Center and Lankenau Institute for Medical Research, Wynnewood, PA, USA
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The short QT syndrome: proposed diagnostic criteria. J Am Coll Cardiol 2011; 57:802-12. [PMID: 21310316 DOI: 10.1016/j.jacc.2010.09.048] [Citation(s) in RCA: 181] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 08/20/2010] [Accepted: 09/27/2010] [Indexed: 12/25/2022]
Abstract
OBJECTIVES We aimed to develop diagnostic criteria for the short QT syndrome (SQTS) to facilitate clinical evaluation of suspected cases. BACKGROUND The SQTS is a cardiac channelopathy associated with atrial fibrillation and sudden cardiac death. Ten years after its original description, a consensus regarding an appropriate QT interval cutoff and specific diagnostic criteria have yet to be established. METHODS The MEDLINE database was searched for all reported cases of SQTS in the English language, and all relevant data were extracted. The distribution of QT intervals and electrocardiographic (ECG) features in affected cases were analyzed and compared to data derived from ECG analysis from general population studies. RESULTS A total of 61 reported cases of SQTS were identified. Index events, including sudden cardiac death, aborted cardiac arrest, syncope, and/or atrial fibrillation occurred in 35 of 61 (57.4%) cases. The cohort was predominantly male (75.4%) and had a mean QT(c) value of 306.7 ms with values ranging from 248 to 381 ms in symptomatic cases. In reference to the ECG characteristics of the general population, and in consideration of clinical presentation, family history, and genetic findings, a highly sensitive diagnostic scoring system was developed. CONCLUSIONS Based on a comprehensive review of 61 reported cases of the SQTS, formal diagnostic criteria have been proposed that will facilitate diagnostic evaluation in suspected cases of SQTS. Diagnostic criteria may lead to a greater recognition of this condition and provoke screening of at-risk family members.
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Antzelevitch C, Burashnikov A. Overview of Basic Mechanisms of Cardiac Arrhythmia. Card Electrophysiol Clin 2011; 3:23-45. [PMID: 21892379 DOI: 10.1016/j.ccep.2010.10.012] [Citation(s) in RCA: 203] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Sun Y, Quan XQ, Fromme S, Cox RH, Zhang P, Zhang L, Guo D, Guo J, Patel C, Kowey PR, Yan GX. A novel mutation in the KCNH2 gene associated with short QT syndrome. J Mol Cell Cardiol 2011; 50:433-41. [DOI: 10.1016/j.yjmcc.2010.11.017] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2010] [Revised: 11/18/2010] [Accepted: 11/22/2010] [Indexed: 11/28/2022]
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Affiliation(s)
- Chinmay Patel
- Main Line Health Heart Center and Lankenau Hospital, Wynnewood, PA, USA
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Vatta M. Genetic variants and ECG pattern variability in long QT syndrome: How far are we? Heart Rhythm 2010; 7:904-5. [DOI: 10.1016/j.hrthm.2010.04.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Indexed: 10/19/2022]
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Watanabe H, Makiyama T, Koyama T, Kannankeril PJ, Seto S, Okamura K, Oda H, Itoh H, Okada M, Tanabe N, Yagihara N, Kamakura S, Horie M, Aizawa Y, Shimizu W. High prevalence of early repolarization in short QT syndrome. Heart Rhythm 2010; 7:647-52. [DOI: 10.1016/j.hrthm.2010.01.012] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2009] [Accepted: 01/09/2010] [Indexed: 01/12/2023]
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Crotti L, Taravelli E, Girardengo G, Schwartz PJ. Congenital short QT syndrome. Indian Pacing Electrophysiol J 2010; 10:86-95. [PMID: 20126594 PMCID: PMC2811207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The Short QT Syndrome is a recently described new genetic disorder, characterized by abnormally short QT interval, paroxysmal atrial fibrillation and life threatening ventricular arrhythmias. This autosomal dominant syndrome can afflict infants, children, or young adults; often a remarkable family background of cardiac sudden death is elucidated. At electrophysiological study, short atrial and ventricular refractory periods are found, with atrial fibrillation and polymorphic ventricular tachycardia easily induced by programmed electrical stimulation. Gain of function mutations in three genes encoding K(+) channels have been identified, explaining the abbreviated repolarization seen in this condition: KCNH2 for I(kr) (SQT1), KCNQ1 for I(ks) (SQT2) and KCNJ2 for I(k1) (SQT3). The currently suggested therapeutic strategy is an ICD implantation, although many concerns exist for asymptomatic patients, especially in pediatric age. Pharmacological treatment is still under evaluation; quinidine has shown to prolong QT and reduce the inducibility of ventricular arrhythmias, but awaits additional confirmatory clinical data.
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Affiliation(s)
- Lia Crotti
- Section of Cardiology, Department of Lung, Blood and Heart, University of Pavia, Pavia, Italy ,Department of Cardiology, IRCCS Fondazione Policlinico S. Matteo, Pavia, Italy,Molecular Cardiology Laboratory, IRCCS Fondazione Policlinico S. Matteo, Pavia, Italy
| | - Erika Taravelli
- Section of Cardiology, Department of Lung, Blood and Heart, University of Pavia, Pavia, Italy ,Department of Cardiology, IRCCS Fondazione Policlinico S. Matteo, Pavia, Italy
| | - Giulia Girardengo
- Section of Cardiology, Department of Lung, Blood and Heart, University of Pavia, Pavia, Italy ,Department of Cardiology, IRCCS Fondazione Policlinico S. Matteo, Pavia, Italy
| | - Peter J Schwartz
- Section of Cardiology, Department of Lung, Blood and Heart, University of Pavia, Pavia, Italy ,Department of Cardiology, IRCCS Fondazione Policlinico S. Matteo, Pavia, Italy,Molecular Cardiology Laboratory, IRCCS Fondazione Policlinico S. Matteo, Pavia, Italy,Laboratory of Cardiovascular Genetics, IRCCS Istituto Auxologico, Milan, Italy,Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research, University of Cape Town, Cape Town, South Africa,Sudden Death Chair, King Saud University, Riyadh, Saudi Arabia
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Shah RR. Drug-induced QT interval shortening: potential harbinger of proarrhythmia and regulatory perspectives. Br J Pharmacol 2010; 159:58-69. [PMID: 19563537 PMCID: PMC2823352 DOI: 10.1111/j.1476-5381.2009.00191.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 01/07/2009] [Accepted: 01/14/2009] [Indexed: 01/08/2023] Open
Abstract
ATP-dependent potassium channel openers such as pinacidil and levcromakalim have long been known to shorten action potential duration and to be profibrillatory in non-clinical models, raising concerns on the clinical safety of drugs that shorten QT interval. Routine non-clinical evaluation of new drugs for their potential to affect cardiac repolarization has revealed that drugs may also shorten QT interval. The description of congenital short QT syndrome in 2000, together with the associated arrhythmias, suggests that drug-induced short QT interval may be proarrhythmic, and an uncanny parallel is evolving between our appreciation of the short and the long QT intervals. Epidemiological studies report an over-representation of short QT interval values in patients with idiopathic ventricular fibrillation. Therefore, as new compounds that shorten QT interval are progressed further into clinical development, questions will inevitably arise on their safety. Arising from the current risk-averse clinical and regulatory environment and concerns on proarrhythmic safety of drugs, together with our lack of a better understanding of the clinical significance of short QT interval, new drugs that substantially shorten QT interval will likely receive an unfavourable regulatory review unless these drugs fulfil an unmet clinical need. This review provides estimates of parameters of QT shortening that may be of potential clinical significance. Rufinamide, a recently approved anticonvulsant, illustrates the current regulatory approach to drugs that shorten QT interval. However, to further substantiate or confirm the safety of these drugs, their approval may well be conditional upon large-scale post-marketing studies with a focus on cardiac safety.
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Affiliation(s)
- Rashmi R Shah
- Medicines and Healthcare products Regulatory Agency, London, UK.
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Hedley PL, Jørgensen P, Schlamowitz S, Wangari R, Moolman-Smook J, Brink PA, Kanters JK, Corfield VA, Christiansen M. The genetic basis of long QT and short QT syndromes: A mutation update. Hum Mutat 2009; 30:1486-511. [DOI: 10.1002/humu.21106] [Citation(s) in RCA: 318] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Anttonen O, Junttila J, Giustetto C, Gaita F, Linna E, Karsikas M, Seppänen T, Perkiömäki JS, Mäkikallio TH, Brugada R, Huikuri HV. T-Wave morphology in short QT syndrome. Ann Noninvasive Electrocardiol 2009; 14:262-7. [PMID: 19614638 DOI: 10.1111/j.1542-474x.2009.00308.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Short QT syndrome (SQTS) is an inherited disorder characterized by a short QT interval and vulnerability to ventricular tachyarrhythmias. The diagnostic criteria for this syndrome are not well defined, since there is uncertainty about the lowest normal limits for the corrected QT (QTc) interval. OBJECTIVE The aim of this study was to determine whether T-wave morphology parameters are abnormal in short QT subjects and whether those parameters can help in the diagnosis of SQTS. METHODS AND RESULTS We describe three families (10 patients) with short QT intervals (QTc 310 +/- 32 ms). Seven subjects had suffered serious arrhythmic events and three were asymptomatic. T-wave morphology was assessed using the principal component analysis (PCA). QTc was significantly shorter and T-wave amplitude in lead V2 higher in the short QT subjects compared to healthy controls (n=149), (P < 0.001 for both). The total cosine of the angle between the main vectors of the QRS and T-wave loops (TCRT) was markedly abnormal among the symptomatic patients with short QT syndrome (n=7) (TCRT -0.14 +/- 0.55 vs 0.36 +/- 0.51, P=0.019). None of the three asymptomatic patients with short QT but without a history of arrhythmic events had an abnormally low TCRT. CONCLUSION Our observations suggest that patients with a short QT interval and a history of arrhythmic events have abnormal T-wave loop parameters. These electrocardiogram (ECG) features may help in the diagnosis of SQTS in addition to the measurement of the duration of QT interval from the 12-lead ECG.
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Sabir IN, Killeen MJ, Grace AA, Huang CLH. Ventricular arrhythmogenesis: Insights from murine models. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:208-18. [DOI: 10.1016/j.pbiomolbio.2008.10.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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