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Abstract
Long QT syndrome (LQTS) is a detrimental arrhythmia syndrome mainly caused by dysregulated expression or aberrant function of ion channels. The major clinical symptoms of ventricular arrhythmia, palpitations and syncope vary among LQTS subtypes. Susceptibility to malignant arrhythmia is a result of delayed repolarisation of the cardiomyocyte action potential (AP). There are 17 distinct subtypes of LQTS linked to 15 autosomal dominant genes with monogenic mutations. However, due to the presence of modifier genes, the identical mutation may result in completely different clinical manifestations in different carriers. In this review, we describe the roles of various ion channels in orchestrating APs and discuss molecular aetiologies of various types of LQTS. We highlight the usage of patient-specific induced pluripotent stem cell (iPSC) models in characterising fundamental mechanisms associated with LQTS. To mitigate the outcomes of LQTS, treatment strategies are initially focused on small molecules targeting ion channel activities. Next-generation treatments will reap the benefits from development of LQTS patient-specific iPSC platform, which is bolstered by the state-of-the-art technologies including whole-genome sequencing, CRISPR genome editing and machine learning. Deep phenotyping and high-throughput drug testing using LQTS patient-specific cardiomyocytes herald the upcoming precision medicine in LQTS.
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Torsades de Pointes due to Excessive Marijuana Use in a Susceptible Patient. Case Rep Cardiol 2021; 2021:6621496. [PMID: 34336299 PMCID: PMC8292089 DOI: 10.1155/2021/6621496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 06/15/2021] [Indexed: 11/17/2022] Open
Abstract
There are several recent reports of tetrahydrocannabinol vaping-related sudden cardiac arrest, and the mechanisms are unclear. We report a unique case of a 19-year-old female who suffered documented prolonged QTc leading to Torsades de pointes and cardiac arrest in the setting of frequent marijuana wax vaping. While she demonstrated normal baseline QTc measurements years earlier, she was found to have a genetic predisposition to QTc prolongation (genetic mutation, family history of prolonged QTc), suggesting that specific patient populations are at higher risk of these adverse events. The patient was acutely managed with isoproterenol to increase the heart rate and was discharged on nadolol after placement of an implantable cardioverter-defibrillator. Marijuana wax vaping and dabbing may cause fatal Torsades de pointes in susceptible patients, and further research is required to identify these patients a priori.
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Simpson KE, Venkateshappa R, Pang ZK, Faizi S, Tibbits GF, Claydon TW. Utility of Zebrafish Models of Acquired and Inherited Long QT Syndrome. Front Physiol 2021; 11:624129. [PMID: 33519527 PMCID: PMC7844309 DOI: 10.3389/fphys.2020.624129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/21/2020] [Indexed: 01/12/2023] Open
Abstract
Long-QT Syndrome (LQTS) is a cardiac electrical disorder, distinguished by irregular heart rates and sudden death. Accounting for ∼40% of cases, LQTS Type 2 (LQTS2), is caused by defects in the Kv11.1 (hERG) potassium channel that is critical for cardiac repolarization. Drug block of hERG channels or dysfunctional channel variants can result in acquired or inherited LQTS2, respectively, which are typified by delayed repolarization and predisposition to lethal arrhythmia. As such, there is significant interest in clear identification of drugs and channel variants that produce clinically meaningful perturbation of hERG channel function. While toxicological screening of hERG channels, and phenotypic assessment of inherited channel variants in heterologous systems is now commonplace, affordable, efficient, and insightful whole organ models for acquired and inherited LQTS2 are lacking. Recent work has shown that zebrafish provide a viable in vivo or whole organ model of cardiac electrophysiology. Characterization of cardiac ion currents and toxicological screening work in intact embryos, as well as adult whole hearts, has demonstrated the utility of the zebrafish model to contribute to the development of therapeutics that lack hERG-blocking off-target effects. Moreover, forward and reverse genetic approaches show zebrafish as a tractable model in which LQTS2 can be studied. With the development of new tools and technologies, zebrafish lines carrying precise channel variants associated with LQTS2 have recently begun to be generated and explored. In this review, we discuss the present knowledge and questions raised related to the use of zebrafish as models of acquired and inherited LQTS2. We focus discussion, in particular, on developments in precise gene-editing approaches in zebrafish to create whole heart inherited LQTS2 models and evidence that zebrafish hearts can be used to study arrhythmogenicity and to identify potential anti-arrhythmic compounds.
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Affiliation(s)
- Kyle E. Simpson
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Ravichandra Venkateshappa
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Zhao Kai Pang
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Shoaib Faizi
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Glen F. Tibbits
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
- Department of Cardiovascular Science, British Columbia Children’s Hospital, Vancouver, BC, Canada
| | - Tom W. Claydon
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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Avidan OR, Tayebi K, Del Toro K, Warrier R. Seizure After Minor Head Trauma: A Red Herring? Clin Pediatr (Phila) 2021; 60:64-66. [PMID: 32723078 DOI: 10.1177/0009922820941643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | - Kasra Tayebi
- University of Queensland, Herston, Queensland, Australia
| | - Kamil Del Toro
- University of Queensland, Herston, Queensland, Australia.,Ochsner Children's Hospital, New Orleans, LA, USA
| | - Rajasekharan Warrier
- University of Queensland, Herston, Queensland, Australia.,Ochsner Children's Hospital, New Orleans, LA, USA
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Saboe A, Sari MT, Febrianora M. A rare manifestation of Takotsubo Cardiomyopathy associated with non-tuberculous mycobacterium. J Clin Tuberc Other Mycobact Dis 2020; 21:100191. [PMID: 32995573 PMCID: PMC7516290 DOI: 10.1016/j.jctube.2020.100191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Background Takotsubo Cardiomyopathy or broken heart syndrome is a rare cause of non-ischemic cardiomyopathy that produce left ventricular dysfunction with characteristic left ventricular apical ballooning. It rarely caused by infection. We present an atypical manifestation of non-tuberculous mycobacterial (NTM) infection with myocardial involvement and its diagnostic challenge. Case illustration A 57-year-old female presented with prolonged fever, fatigue and weight loss for one and half months. General examination was unremarkable with elevated C-Reactive Protein and normal troponin. Electrocardiogram (ECG) showed diffuse T wave inversion with prolonged QTc. Echocardiography showed hypokinetic apical with normal ejection fraction. Angiography showed patent coronary arteries. Ventriculography showed apical ballooning. Workup with ethambutol scan revealed active mycobacterial infection in both lung and mesentery. Sputum polymerase chain reaction (PCR) was positive for non-tuberculous mycobacterium. Follow up ECG and echocardiography showed improvement in QTc interval and left ventricular wall motion abnormalities. Results Takotsubo Cardiomyopathy may manifest as asymptomatic ventricular dysfunction following non-tuberculous mycobacterial infection. A thorough investigation will help identify the systemic disease with cardiac involvement which potentially could be fatal. Conclusion Takotsubo cardiomyopathy may be triggered by infection. Identification of causal is crucial as a management strategy to restore cardiac function.
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Affiliation(s)
- Aninka Saboe
- Department of Cardiology and Vascular Medicine, Universitas Padjadjaran - Hasan Sadikin General Hospital, Bandung, Indonesia
| | - Minsy Titi Sari
- Department of Cardiology and Vascular Medicine, Universitas Padjadjaran - Hasan Sadikin General Hospital, Bandung, Indonesia
| | - Mega Febrianora
- Department of Cardiology and Vascular Medicine, Universitas Padjadjaran - Hasan Sadikin General Hospital, Bandung, Indonesia
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Alahmadi A, Davies A, Vigo M, Jay C. Pseudo-colouring an ECG enables lay people to detect QT-interval prolongation regardless of heart rate. PLoS One 2020; 15:e0237854. [PMID: 32853262 PMCID: PMC7451551 DOI: 10.1371/journal.pone.0237854] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 08/04/2020] [Indexed: 01/08/2023] Open
Abstract
Drug-induced long QT syndrome (diLQTS), characterized by a prolongation of the QT-interval on the electrocardiogram (ECG), is a serious adverse drug reaction that can cause the life-threatening arrhythmia Torsade de Points (TdP). Self-monitoring for diLQTS could therefore save lives, but detecting it on the ECG is difficult, particularly at high and low heart rates. In this paper, we evaluate whether using a pseudo-colouring visualisation technique and changing the coordinate system (Cartesian vs. Polar) can support lay people in identifying QT-prolongation at varying heart rates. Four visualisation techniques were evaluated using a counterbalanced repeated measures design including Cartesian no-colouring, Cartesian pseudo-colouring, Polar no-colouring and Polar pseudo-colouring. We used a multi-reader, multi-case (MRMC) receiver operating characteristic (ROC) study design within a psychophysical paradigm, along with eye-tracking technology. Forty-three lay participants read forty ECGs (TdP risk n = 20, no risk n = 20), classifying each QT-interval as normal/abnormal, and rating their confidence on a 6-point scale. The results show that introducing pseudo-colouring to the ECG significantly increased accurate detection of QT-interval prolongation regardless of heart rate, T-wave morphology and coordinate system. Pseudo-colour also helped to reduce reaction times and increased satisfaction when reading the ECGs. Eye movement analysis indicated that pseudo-colour helped to focus visual attention on the areas of the ECG crucial to detecting QT-prolongation. The study indicates that pseudo-colouring enables lay people to visually identify drug-induced QT-prolongation regardless of heart rate, with implications for the more rapid identification and management of diLQTS.
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Affiliation(s)
- Alaa Alahmadi
- Department of Computer Science, The University of Manchester, Manchester, United Kingdom
| | - Alan Davies
- Division of Informatics, Imaging and Data Sciences, School of Health Sciences, The University of Manchester, Manchester, United Kingdom
| | - Markel Vigo
- Department of Computer Science, The University of Manchester, Manchester, United Kingdom
| | - Caroline Jay
- Department of Computer Science, The University of Manchester, Manchester, United Kingdom
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Al Riyami H, Hussain A, Warren A, Dhillon SS. Practice Variation in Establishing the Adequacy of Beta-Blockers as an Antiarrhythmic Agent in School-Aged Children and Adolescents. CJC Open 2020; 2:244-248. [PMID: 32695975 PMCID: PMC7365819 DOI: 10.1016/j.cjco.2020.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/12/2020] [Indexed: 10/25/2022] Open
Abstract
Background Beta-blockers (BBs) are commonly prescribed to manage arrhythmias in children and adolescents without any standardised approach to establish BB adequacy. We invited all Canadian pediatric cardiologists to participate in an anonymous survey to understand practice variation in the assessment of BB adequacy in school-aged children and adolescents with arrhythmia or the potential for arrhythmia. Methods An electronic survey approved by the Institutional Ethics Board was distributed by e-mail to 96 Canadian pediatric cardiologists who had been active in practice for at least 1 year. Incomplete surveys were excluded. Results Forty-one cardiologists (43%) responded to all questions in the survey. Thirteen cardiologists (32%) reported always assessing BB adequacy, 17 (41%) did so only for specific arrhythmias, and 11 (27%) reported never performing such an assessment. A total of 19 cardiologists (46%) and 18 cardiologists (44%) reported using Holter monitoring and exercise testing, respectively, to assess beta receptor blockade adequacy. Thirteen cardiologists (32%) considered BB therapy adequate if Holter demonstrated a 20% decrease in heart rate (HR) from baseline, and 10 respondents (24%) defined adequate BB therapy using exercise testing as a 20% decrease in maximal HR or blood pressure from baseline. Conclusion Despite wide variation in practice, Holter monitoring and exercise testing are commonly used methods to measure the adequacy of BB therapy. There are no standard criteria, but the majority (56%) reported using a 20% decrease in HR or blood pressure from the pretreatment state as a criterion for adequate BB therapy in children and adolescents with arrhythmia or the potential for arrhythmia.
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Affiliation(s)
- Hilal Al Riyami
- Division of Cardiology, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Arif Hussain
- Division of Cardiology, Department of Pediatrics, Dalhousie University/Izaak-Walton-Killam, Health Centre, Halifax, Nova Scotia, Canada
| | - Andrew Warren
- Division of Cardiology, Department of Pediatrics, Dalhousie University/Izaak-Walton-Killam, Health Centre, Halifax, Nova Scotia, Canada
| | - Santokh S Dhillon
- Division of Cardiology, Department of Pediatrics, Dalhousie University/Izaak-Walton-Killam, Health Centre, Halifax, Nova Scotia, Canada
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Kernik DC, Morotti S, Wu H, Garg P, Duff HJ, Kurokawa J, Jalife J, Wu JC, Grandi E, Clancy CE. A computational model of induced pluripotent stem-cell derived cardiomyocytes incorporating experimental variability from multiple data sources. J Physiol 2019; 597:4533-4564. [PMID: 31278749 PMCID: PMC6767694 DOI: 10.1113/jp277724] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 07/05/2019] [Indexed: 12/22/2022] Open
Abstract
Key points Induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs) capture patient‐specific genotype–phenotype relationships, as well as cell‐to‐cell variability of cardiac electrical activity Computational modelling and simulation provide a high throughput approach to reconcile multiple datasets describing physiological variability, and also identify vulnerable parameter regimes We have developed a whole‐cell model of iPSC‐CMs, composed of single exponential voltage‐dependent gating variable rate constants, parameterized to fit experimental iPSC‐CM outputs We have utilized experimental data across multiple laboratories to model experimental variability and investigate subcellular phenotypic mechanisms in iPSC‐CMs This framework links molecular mechanisms to cellular‐level outputs by revealing unique subsets of model parameters linked to known iPSC‐CM phenotypes
Abstract There is a profound need to develop a strategy for predicting patient‐to‐patient vulnerability in the emergence of cardiac arrhythmia. A promising in vitro method to address patient‐specific proclivity to cardiac disease utilizes induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs). A major strength of this approach is that iPSC‐CMs contain donor genetic information and therefore capture patient‐specific genotype–phenotype relationships. A cited detriment of iPSC‐CMs is the cell‐to‐cell variability observed in electrical activity. We postulated, however, that cell‐to‐cell variability may constitute a strength when appropriately utilized in a computational framework to build cell populations that can be employed to identify phenotypic mechanisms and pinpoint key sensitive parameters. Thus, we have exploited variation in experimental data across multiple laboratories to develop a computational framework for investigating subcellular phenotypic mechanisms. We have developed a whole‐cell model of iPSC‐CMs composed of simple model components comprising ion channel models with single exponential voltage‐dependent gating variable rate constants, parameterized to fit experimental iPSC‐CM data for all major ionic currents. By optimizing ionic current model parameters to multiple experimental datasets, we incorporate experimentally‐observed variability in the ionic currents. The resulting population of cellular models predicts robust inter‐subject variability in iPSC‐CMs. This approach links molecular mechanisms to known cellular‐level iPSC‐CM phenotypes, as shown by comparing immature and mature subpopulations of models to analyse the contributing factors underlying each phenotype. In the future, the presented models can be readily expanded to include genetic mutations and pharmacological interventions for studying the mechanisms of rare events, such as arrhythmia triggers. Induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs) capture patient‐specific genotype–phenotype relationships, as well as cell‐to‐cell variability of cardiac electrical activity Computational modelling and simulation provide a high throughput approach to reconcile multiple datasets describing physiological variability, and also identify vulnerable parameter regimes We have developed a whole‐cell model of iPSC‐CMs, composed of single exponential voltage‐dependent gating variable rate constants, parameterized to fit experimental iPSC‐CM outputs We have utilized experimental data across multiple laboratories to model experimental variability and investigate subcellular phenotypic mechanisms in iPSC‐CMs This framework links molecular mechanisms to cellular‐level outputs by revealing unique subsets of model parameters linked to known iPSC‐CM phenotypes
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Affiliation(s)
- Divya C Kernik
- Department of Physiology and Membrane Biology, Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, USA
| | - Stefano Morotti
- Department of Pharmacology, School of Medicine, University of California, Davis, CA, USA
| | - HaoDi Wu
- Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Priyanka Garg
- Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Henry J Duff
- Libin Cardiovascular Institute of Alberta, Faculty of Medicine, University of Calgary, Calgary, AB, Canada
| | - Junko Kurokawa
- Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - José Jalife
- Department of Internal Medicine, Center for Arrhythmia Research, Cardiovascular Research Center, University of Michigan, Ann Arbor, MI, USA.,Centro Nacional de Investigaciones Cardiovasculares (CNIC), and CIBERV, Madrid, Spain
| | - Joseph C Wu
- Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, School of Medicine, University of California, Davis, CA, USA
| | - Colleen E Clancy
- Department of Physiology and Membrane Biology, Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, USA
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Alahmadi A, Davies A, Vigo M, Jay C. Can laypeople identify a drug-induced QT interval prolongation? A psychophysical and eye-tracking experiment examining the ability of nonexperts to interpret an ECG. J Am Med Inform Assoc 2019; 26:404-411. [PMID: 30848818 PMCID: PMC7787352 DOI: 10.1093/jamia/ocy183] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 11/22/2018] [Accepted: 12/10/2018] [Indexed: 01/10/2023] Open
Abstract
Objective The study sought to quantify a layperson’s ability to detect drug-induced QT interval prolongation on an electrocardiogram (ECG) and determine whether the presentation of the trace affects such detection. Materials and Methods Thirty layperson participants took part in a psychophysical and eye-tracking experiment. Following training, participants completed 21 experimental trials, in which each trial consisted of 2 ECGs (a baseline and a comparison stimulus, both with a heart rate of 60 beats/min). The experiment used a 1 alternative forced-choice paradigm, in which participants indicated whether or not they perceived a difference in the QT interval length between the 2 ECGs. The ECG trace was presented in 3 ways: a single complex with the signals aligned by the R wave, a single complex without alignment, and a 10-second rhythm strip. Performance was analyzed using the psychometric function to estimate the just noticeable difference threshold, along with eye-tracking metrics. Results The just noticeable difference 50% and 75% thresholds were 30 and 88 ms, respectively, showing that the majority of laypeople were able to detect a clinically significant QT-prolongation at a low normal heart rate. Eye movement data indicated that people were more likely to appraise the rhythm strip stimulus systematically and accurately. Conclusions People can quickly be trained to self-monitor, which may help with more rapid identification of drug-induced long QT syndrome and prevent the development of life-threatening complications. The rhythm strip is a better form of presentation than a single complex, as it is less likely to be misinterpreted due to artifacts in the signal.
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Affiliation(s)
- Alaa Alahmadi
- University of Manchester, School of Computer Science, Manchester, UK
| | - Alan Davies
- University of Manchester, School of Computer Science, Manchester, UK
| | - Markel Vigo
- University of Manchester, School of Computer Science, Manchester, UK
| | - Caroline Jay
- University of Manchester, School of Computer Science, Manchester, UK
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Laksman Z, Barichello S, Roston TM, Deyell MW, Krahn AD. Acute Management of Ventricular Arrhythmia in Patients With Suspected Inherited Heart Rhythm Disorders. JACC Clin Electrophysiol 2019; 5:267-283. [DOI: 10.1016/j.jacep.2019.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/02/2019] [Accepted: 02/03/2019] [Indexed: 02/08/2023]
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Guerri G, Krasi G, Precone V, Paolacci S, Chiurazzi P, Arrigoni L, Cortese B, Dautaj A, Bertelli M. Cardiac conduction defects. ACTA BIO-MEDICA : ATENEI PARMENSIS 2019; 90:20-29. [PMID: 31577249 PMCID: PMC7233635 DOI: 10.23750/abm.v90i10-s.8751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 08/05/2019] [Indexed: 11/11/2022]
Abstract
Defects in cardiac electric impulse formation or conduction can lead to an irregular beat (arrhythmia) that can cause sudden death without any apparent cause or after stress. In the following sections, we describe the genetic disorders associated with primary cardiac conduction defects, primarily caused by mutations in ion channel genes. Primary indicates that these disorders are not caused by drugs and are not secondary to other disorders like cardiomyopathies (described in the next section).
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Affiliation(s)
- Giulia Guerri
- Authors have equally contributed to this work, MAGI’s Lab, Rovereto (TN), Italy
| | - Geraldo Krasi
- Authors have equally contributed to this work, MAGI Balkans, Tirana, Albania
| | | | - Stefano Paolacci
- MAGI’s Lab, Rovereto (TN), Italy,Correspondence: Stefano Paolacci Via delle Maioliche 57/D 38068 Rovereto (TN), Italy E-mail:
| | - Pietro Chiurazzi
- Istituto di Medicina Genomica, Università Cattolica del Sacro Cuore, Rome, Italy, UOC Genetica Medica, Fondazione Policlinico Universitario “A. Gemelli”, Rome, Italy
| | - Luca Arrigoni
- Section of Cardiovascular Diseases, Department of Clinical and Surgical Specialities, Radiological Sciences and Public Health, University and Spedali Civili Hospital of Brescia, Italy
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Papp R, Bett GCL, Lis A, Rasmusson RL, Baczkó I, Varró A, Salama G. Genomic upregulation of cardiac Cav1.2α and NCX1 by estrogen in women. Biol Sex Differ 2017; 8:26. [PMID: 28807015 PMCID: PMC5557418 DOI: 10.1186/s13293-017-0148-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/04/2017] [Indexed: 01/08/2023] Open
Abstract
Background Women have a higher risk of lethal arrhythmias than men in long QT syndrome type 2 (LQTS2), but the mechanisms remain uncertain due to the limited availability of healthy control human tissue. We have previously reported that in female rabbits, estrogen increases arrhythmia risk in drug-induced LQTS2 by upregulating L-type Ca2+ (ICa,L) and sodium-calcium exchange (INCX) currents at the base of the epicardium by a genomic mechanism. This study investigates if the effects of estrogen on rabbit ICa,L and INCX apply to human hearts. Methods Postmortem human left ventricular tissue samples were probed with selective antibodies for regional heterogeneities of ion channel protein expression and compared to rabbit myocardium. Functionally, ICa,L and INCX were measured from female and male cardiomyocytes derived from human induced pluripotent stem cells (iPS-CMs) with the voltage-clamp technique from control and estrogen-treated iPS-CMs. Results In women (n = 12), Cav1.2α (primary subunit of the L-type calcium channel protein 1) and NCX1 (sodium-calcium exchange protein) levels were higher at the base than apex of the epicardium (40 ± 14 and 81 ± 30%, respectively, P < 0.05), but not in men (n = 6) or postmenopausal women (n = 6). Similarly, in cardiomyocytes derived from female human iPS-CMs, estrogen (1 nM, 1–2 days) increased ICa,L (31%, P < 0.05) and INCX (7.5-fold, − 90 mV, P < 0.01) and their mRNA levels (P < 0.05). Moreover, in male human iPS-CMs, estrogen failed to alter ICa,L and INCX. Conclusions The results show that estrogen upregulates cardiac ICa,L and INCX in women through genomic mechanisms that account for sex differences in Ca2+ handling and spatial heterogeneities of repolarization due to base-apex heterogeneities of Cav1.2α and NCX1. By analogy with rabbit studies, these effects account for human sex-difference in arrhythmia risk.
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Affiliation(s)
- Rita Papp
- Department of Bioengineering and the Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, 15261, USA.,Current Address: Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria
| | - Glenna C L Bett
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.,Department of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.,Obstetrics-Gynecology, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - Agnieszka Lis
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.,Department of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - Randall L Rasmusson
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.,Department of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.,MTA-SZTE Research Group for Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Guy Salama
- Department of Bioengineering and the Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, 15261, USA. .,Department of Bioengineering and the Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, 3550 Terrace Street, S628 Scaife Hall, Pittsburgh, PA, 15261, USA.
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Abstract
Ion channels in the myocardial cellular membrane are responsible for allowing the cardiac action potential. Genetic abnormalities in these channels can predispose to life-threatening arrhythmias. We discuss the basic science of the cardiac action potential; outline the different clinical entities, including information regarding overlapping diagnoses, touching upon relevant genetics, new innovations in screening, diagnosis, risk stratification, and management. The special considerations of sudden unexplained death and sudden infant death syndrome are discussed. Scientists and clinicians continue to reconcile the rapidly growing body of knowledge regarding the molecular mechanisms and genetics while continuing to improve our understanding of the various clinical entities and their diagnosis and management in clinical setting. Two separate searches were run on the National Center for Biotechnology Information's website. The first using the term cardiac channelopathies was run on the PubMed database using filters for time (published in past 5 years) and age (birth-18 years), yielding 47 results. The second search using the medical subject headings (MeSH) database with the search terms “Long QT Syndrome” (MeSH) and “Short QT Syndrome” (MeSH) and “Brugada Syndrome” (MeSH) and “Catecholaminergic Polymorphic Ventricular Tachycardia” (MeSH), applying the same filters yielded 467 results. The abstracts of these articles were studied, and the articles were categorized and organized. Articles of relevance were read in full. As and where applicable, relevant references and citations from the primary articles where further explored and read in full.
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Affiliation(s)
- Shashank P Behere
- Department of Pediatrics, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Steven N Weindling
- Department of Pediatric Cardiology, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA
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14
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Collins RT, Aziz PF, Gleason MM, Kaplan PB, Shah MJ. Abnormalities of cardiac repolarization in Williams syndrome. Am J Cardiol 2010; 106:1029-33. [PMID: 20854969 DOI: 10.1016/j.amjcard.2010.05.041] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 05/14/2010] [Accepted: 05/14/2010] [Indexed: 11/26/2022]
Abstract
Williams syndrome (WS) affects 1 in 8,000 live births and has a high risk of sudden death. No previous studies have evaluated corrected QT (QTc) prolongation in WS. Retrospective review of all patients with WS evaluated at our institution from January 1, 1980 to December 31, 2007 was performed. WS was diagnosed by a medical geneticist and/or by fluorescence in situ hybridization. Patients with ≥1 electrocardiogram (ECG) with sinus rhythm and measurable intervals were included. Normal control ECGs were identified from a large clinical database. Corrected JT (JTc) interval was calculated when QRS and QTc intervals were prolonged. QTc interval ≥460 ms and JTc interval >340 ms were defined as prolonged. Prevalence comparisons were made using Fisher's exact test. Statistical probability of <0.05 was considered significant. Of 270 patients identified, 188 had ECGs for review. Complete data were present in 499 of 517 ECGs (patients' mean age 10.3 ± 9.9 years); 1,522 normal ECGs of age-similar patients composed the control group. QTc prolongation prevalences were 2.0% in controls and 13.6% in WS (p <0.0001); in those, JTc prolongation prevalences were 1.8% in controls and 11.7% in WS (p <0.0001). Four patients died during follow-up; 2 had QTc prolongation and 1 died during noncardiac surgery. Another patient with QTc prolongation sustained cardiac arrest during a procedure. In conclusion, cardiac repolarization is prolonged in WS. Presence of prolonged cardiac repolarization may contribute to the high incidence of periprocedural mortality in these patients. All patients with WS should be screened for cardiac repolarization abnormalities, especially before surgery.
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