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Morris PG, Taylor JD, Paton JFR, Nogaret A. Single shot detection of alterations across multiple ionic currents from assimilation of cell membrane dynamics. Sci Rep 2024; 14:6031. [PMID: 38472404 DOI: 10.1038/s41598-024-56576-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/08/2024] [Indexed: 03/14/2024] Open
Abstract
The dysfunction of ion channels is a causative factor in a variety of neurological diseases, thereby defining the implicated channels as key drug targets. The detection of functional changes in multiple specific ionic currents currently presents a challenge, particularly when the neurological causes are either a priori unknown, or are unexpected. Traditional patch clamp electrophysiology is a powerful tool in this regard but is low throughput. Here, we introduce a single-shot method for detecting alterations amongst a range of ion channel types from subtle changes in membrane voltage in response to a short chaotically driven current clamp protocol. We used data assimilation to estimate the parameters of individual ion channels and from these we reconstructed ionic currents which exhibit significantly lower error than the parameter estimates. Such reconstructed currents thereby become sensitive predictors of functional alterations in biological ion channels. The technique correctly predicted which ionic current was altered, and by approximately how much, following pharmacological blockade of BK, SK, A-type K+ and HCN channels in hippocampal CA1 neurons. We anticipate this assay technique could aid in the detection of functional changes in specific ionic currents during drug screening, as well as in research targeting ion channel dysfunction.
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Affiliation(s)
- Paul G Morris
- Department of Physics, University of Bath, Claverton Down, Bath, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Joseph D Taylor
- Department of Physics, University of Bath, Claverton Down, Bath, UK
| | - Julian F R Paton
- Manaaki Manawa - the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Grafton, Auckland, New Zealand
| | - Alain Nogaret
- Department of Physics, University of Bath, Claverton Down, Bath, UK.
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2
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Abrahams T, Davies B, Laksman Z, Sy RW, Postema PG, Wilde AAM, Krahn AD, Han HC. Provocation testing in congenital long QT syndrome: A practical guide. Heart Rhythm 2023; 20:1570-1582. [PMID: 37481219 DOI: 10.1016/j.hrthm.2023.07.059] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/01/2023] [Accepted: 07/14/2023] [Indexed: 07/24/2023]
Abstract
Congenital long QT syndrome (LQTS) is a hereditary cardiac channelopathy with an estimated prevalence of 1 in 2500. A prolonged resting QT interval corrected for heart rate (QTc interval) remains a key diagnostic component; however, the QTc value may be normal in up to 40% of patients with genotype-positive LQTS and borderline in a further 30%. Provocation of QTc prolongation and T-wave changes may be pivotal to unmasking the diagnosis and useful in predicting genotype. LQTS provocation testing involves assessment of repolarization during and after exercise, in response to changes in heart rate or autonomic tone, with patients with LQTS exhibiting a maladaptive repolarization response. We review the utility and strengths and limitations of 4 forms of provocation testing-stand-up test, exercise stress test, epinephrine challenge, and mental stress test-in diagnosing LQTS and provide some practical guidance for performing provocation testing. Ultimately, exercise testing, when feasible, is the most useful form of provocation testing when considering diagnostic sensitivity and specificity.
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Affiliation(s)
- Timothy Abrahams
- Victorian Heart Institute & Monash Health Heart, Victorian Heart Hospital, Monash University, Melbourne, Victoria, Australia
| | - Brianna Davies
- Center for Cardiovascular Innovation, Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Zachary Laksman
- Center for Cardiovascular Innovation, Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Raymond W Sy
- Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Pieter G Postema
- Department of Cardiology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands; Heart Failure & Arrhythmias, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands; European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart (ERN GUARD-Heart), Academic Medical Center, Amsterdam, The Netherlands
| | - Arthur A M Wilde
- Department of Cardiology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands; Heart Failure & Arrhythmias, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands; European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart (ERN GUARD-Heart), Academic Medical Center, Amsterdam, The Netherlands
| | - Andrew D Krahn
- Center for Cardiovascular Innovation, Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Hui-Chen Han
- Victorian Heart Institute & Monash Health Heart, Victorian Heart Hospital, Monash University, Melbourne, Victoria, Australia.
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Senapati SG, Bhanushali AK, Lahori S, Naagendran MS, Sriram S, Ganguly A, Pusa M, Damani DN, Kulkarni K, Arunachalam SP. Mapping of Neuro-Cardiac Electrophysiology: Interlinking Epilepsy and Arrhythmia. J Cardiovasc Dev Dis 2023; 10:433. [PMID: 37887880 PMCID: PMC10607576 DOI: 10.3390/jcdd10100433] [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: 07/16/2023] [Revised: 08/10/2023] [Accepted: 09/22/2023] [Indexed: 10/28/2023] Open
Abstract
The interplay between neurology and cardiology has gained significant attention in recent years, particularly regarding the shared pathophysiological mechanisms and clinical comorbidities observed in epilepsy and arrhythmias. Neuro-cardiac electrophysiology mapping involves the comprehensive assessment of both neural and cardiac electrical activity, aiming to unravel the intricate connections and potential cross-talk between the brain and the heart. The emergence of artificial intelligence (AI) has revolutionized the field by enabling the analysis of large-scale data sets, complex signal processing, and predictive modeling. AI algorithms have been applied to neuroimaging, electroencephalography (EEG), electrocardiography (ECG), and other diagnostic modalities to identify subtle patterns, classify disease subtypes, predict outcomes, and guide personalized treatment strategies. In this review, we highlight the potential clinical implications of neuro-cardiac mapping and AI in the management of epilepsy and arrhythmias. We address the challenges and limitations associated with these approaches, including data quality, interpretability, and ethical considerations. Further research and collaboration between neurologists, cardiologists, and AI experts are needed to fully unlock the potential of this interdisciplinary field.
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Affiliation(s)
- Sidhartha G. Senapati
- Department of Internal Medicine, Texas Tech University Health and Sciences Center, El Paso, TX 79905, USA; (S.G.S.); (D.N.D.)
| | - Aditi K. Bhanushali
- Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA; (A.K.B.); (S.L.)
| | - Simmy Lahori
- Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA; (A.K.B.); (S.L.)
| | | | - Shreya Sriram
- Division of Gastroenterology & Hepatology, Mayo Clinic, Rochester, MN 55905, USA;
| | - Arghyadeep Ganguly
- Department of Internal Medicine, Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, MI 49007, USA;
| | - Mounika Pusa
- Mamata Medical College, Khammam 507002, Telangana, India;
| | - Devanshi N. Damani
- Department of Internal Medicine, Texas Tech University Health and Sciences Center, El Paso, TX 79905, USA; (S.G.S.); (D.N.D.)
- Department of Cardiology, Mayo Clinic, Rochester, MN 55905, USA
| | - Kanchan Kulkarni
- IHU-LIRYC, Heart Rhythm Disease Institute, Fondation Bordeaux Université, Pessac, 33600 Bordeaux, France;
- INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, University of Bordeaux, U1045, 33000 Bordeaux, France
| | - Shivaram P. Arunachalam
- Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA; (A.K.B.); (S.L.)
- Division of Gastroenterology & Hepatology, Mayo Clinic, Rochester, MN 55905, USA;
- Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Zhou Y, Hao N, Sander JW, Lin X, Xiong W, Zhou D. KCNH2 variants in a family with epilepsy and long QT syndrome: A case report and literature review. Epileptic Disord 2023; 25:492-499. [PMID: 36946251 DOI: 10.1002/epd2.20046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 03/07/2023] [Accepted: 03/12/2023] [Indexed: 03/23/2023]
Abstract
OBJECTIVE Genes associated with Long QT syndromes (LQTS), such as KCNQ1, KCNH2, and SCN5A, are common causes of epilepsy. The Arg 744* variant of KCNH2 has been previously reported in people with epilepsy or LQTS, but none of these patients were reported to simultaneously suffer from epilepsy and LQTS. Herein, we report the case of a family with epilepsy and cardiac disorders. METHOD The proband, a 25-year-old woman, with a family history of epilepsy and LQTS was followed at West China Hospital. The proband experienced her first seizure at the age of seven. Video electroencephalograms (vEEGs) showed epileptic discharges. Her 24-h dynamic electrocardiograms 2 (ECGs) showed QTc prolongation. The proband's mother, who is 50 years old, had her first generalized tonic-clonic seizure (GTCS) at the age of 18 years old. After she gave birth at the age of 25, the frequency of seizures increased, so antiepileptic therapy was initiated. When she was 28 years old, she complained of palpitations and syncope for the first time, and QTc prolongation was detected on her 24-h dynamic ECGs. The proband's grandmother also had complaints of palpitations and syncope at the age of 73. Her 24-h dynamic ECGs indicated supraventricular arrhythmia, with the lowest heart rate being 41 bpm, so she agreed to a pacemaker. Considering the young patient's family history, blood samples of the patient and her parents were collected for genetic analysis. RESULTS A heterozygous variant of KCNH2 [c.2230 (exon9) C>T, p. Arg744Ter, 416, NM_000238, rs189014161] was found in the proband and her mother. According to the guidelines of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology, we classified the KCNH2 variant as pathogenic. SIGNIFICANCE This study expands the clinical phenotype of the Arg 744* KCNH2 pathogenic variant. In the context of channelopathies, because of the genetic susceptibility of the brain and the heart, the risk of comorbidity should be considered. This also indicates the importance of precise antiepileptic drug (AED) management and regular ECG monitoring for patients with channelopathies.
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Affiliation(s)
- Yu Zhou
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
| | - Nanya Hao
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
| | - Josemir W Sander
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK
- Chalfont Centre for Epilepsy, Chalfont St Peter, United Kingdom & Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Xu Lin
- Department of Neurology, The Affiliated Chengdu 363 Hospital of Southwest Medical University, Chengdu, Sichuan, China
| | - Weixi Xiong
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
| | - Dong Zhou
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, China
- Institute of Brain Science and Brain-inspired technology of West China Hospital, Sichuan University, Chengdu, China
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Shah R, Gohel A, Gullapalli S, Mathew N, Gopinath S. Shades of a channelopathy-Hypoperfusion, excitability, or both: A case video. Epileptic Disord 2023; 25:422-425. [PMID: 36939698 DOI: 10.1002/epd2.20025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 12/16/2022] [Accepted: 12/20/2022] [Indexed: 03/21/2023]
Abstract
Content available: Video
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Affiliation(s)
- Rutul Shah
- Department of Neurology, Amrita Advanced Centre for Epilepsy, Amrita Institute of Medical Sciences & Research Centre, Kochi, Kerala, India
| | - Abhishek Gohel
- Department of Neurology, Amrita Advanced Centre for Epilepsy, Amrita Institute of Medical Sciences & Research Centre, Kochi, Kerala, India
| | - Sagari Gullapalli
- Department of Neurology, Amrita Advanced Centre for Epilepsy, Amrita Institute of Medical Sciences & Research Centre, Kochi, Kerala, India
| | - Navin Mathew
- Department of Cardiology, Amrita Advanced Centre for Epilepsy, Amrita Institute of Medical Sciences & Research Centre, Kochi, Kerala, India
| | - Siby Gopinath
- Department of Neurology, Amrita Advanced Centre for Epilepsy, Amrita Institute of Medical Sciences & Research Centre, Kochi, Kerala, India
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Mapping the common gene networks that underlie related diseases. Nat Protoc 2023:10.1038/s41596-022-00797-1. [PMID: 36653526 DOI: 10.1038/s41596-022-00797-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 11/21/2022] [Indexed: 01/19/2023]
Abstract
A longstanding goal of biomedicine is to understand how alterations in molecular and cellular networks give rise to the spectrum of human diseases. For diseases with shared etiology, understanding the common causes allows for improved diagnosis of each disease, development of new therapies and more comprehensive identification of disease genes. Accordingly, this protocol describes how to evaluate the extent to which two diseases, each characterized by a set of mapped genes, are colocalized in a reference gene interaction network. This procedure uses network propagation to measure the network 'distance' between gene sets. For colocalized diseases, the network can be further analyzed to extract common gene communities at progressive granularities. In particular, we show how to: (1) obtain input gene sets and a reference gene interaction network; (2) identify common subnetworks of genes that encompass or are in close proximity to all gene sets; (3) use multiscale community detection to identify systems and pathways represented by each common subnetwork to generate a network colocalized systems map; (4) validate identified genes and systems using a mouse variant database; and (5) visualize and further investigate select genes, interactions and systems for relevance to phenotype(s) of interest. We demonstrate the utility of this approach by identifying shared biological mechanisms underlying autism and congenital heart disease. However, this protocol is general and can be applied to any gene sets attributed to diseases or other phenotypes with suspected joint association. A typical NetColoc run takes less than an hour. Software and documentation are available at https://github.com/ucsd-ccbb/NetColoc .
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Du P, Joshi V, Beyder A. Tracking Gut Motility in Organ and Cultures. Methods Mol Biol 2023; 2644:449-466. [PMID: 37142940 DOI: 10.1007/978-1-0716-3052-5_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Gastrointestinal (GI) motility is a key component of digestive health, and it is complex, involving a multitude of cell types and mechanisms to drive both rhythmic and arrhythmic activity. Tracking GI motility in organ and tissue cultures across multiple temporal (seconds, minutes, hours, days) scales can provide valuable information regarding dysmotility and to evaluate treatment options. Here, the chapter describes a simple method to monitor GI motility in organotypic cultures, using a single video camera is placed perpendicularly to the surface of the tissue. A cross-correlational analysis is used to track the relative movements of tissues between subsequent frames and subsequent fitting procedures to fit finite element functions to the deformed tissue to calculate the strain fields. Additional motility index measures from the displacement information are used to further quantify the behaviors of the tissues that are maintained in organotypic culture over days. The protocols presented in this chapter can be adapted to study organotypic cultures from other organs.
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Affiliation(s)
- Peng Du
- Auckland Bioengineering Institute, Department of Engineering Science and Biomedical Engineering, University of Auckland, Auckland, New Zealand.
| | - Vikram Joshi
- Department of Physiology and Biomedical Engineering, Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Arthur Beyder
- Department of Physiology and Biomedical Engineering, Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, USA
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8
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Hoffman JP, Serdiuk AA, Escher AR, Bordoni B, Evans R. Diphenhydramine-Induced Torsade De Pointes With Pharmacological Cardioversion in a Patient With Methadone-Induced QT Prolongation. Cureus 2022; 14:e22534. [PMID: 35228984 PMCID: PMC8865736 DOI: 10.7759/cureus.22534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2022] [Indexed: 11/05/2022] Open
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Rosenthal SB, Willsey HR, Xu Y, Mei Y, Dea J, Wang S, Curtis C, Sempou E, Khokha MK, Chi NC, Willsey AJ, Fisch KM, Ideker T. A convergent molecular network underlying autism and congenital heart disease. Cell Syst 2021; 12:1094-1107.e6. [PMID: 34411509 PMCID: PMC8602730 DOI: 10.1016/j.cels.2021.07.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 05/10/2021] [Accepted: 07/28/2021] [Indexed: 12/29/2022]
Abstract
Patients with neurodevelopmental disorders, including autism, have an elevated incidence of congenital heart disease, but the extent to which these conditions share molecular mechanisms remains unknown. Here, we use network genetics to identify a convergent molecular network underlying autism and congenital heart disease. This network is impacted by damaging genetic variants from both disorders in multiple independent cohorts of patients, pinpointing 101 genes with shared genetic risk. Network analysis also implicates risk genes for each disorder separately, including 27 previously unidentified genes for autism and 46 for congenital heart disease. For 7 genes with shared risk, we create engineered disruptions in Xenopus tropicalis, confirming both heart and brain developmental abnormalities. The network includes a family of ion channels, such as the sodium transporter SCN2A, linking these functions to early heart and brain development. This study provides a road map for identifying risk genes and pathways involved in co-morbid conditions.
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Affiliation(s)
- Sara Brin Rosenthal
- Center for Computational Biology & Bioinformatics, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Helen Rankin Willsey
- Department of Psychiatry and Behavioral Sciences, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuxiao Xu
- Department of Psychiatry and Behavioral Sciences, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuan Mei
- Division of Genetics, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jeanselle Dea
- Department of Psychiatry and Behavioral Sciences, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Sheng Wang
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
| | - Charlotte Curtis
- Division of Genetics, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Emily Sempou
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Mustafa K Khokha
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Neil C Chi
- Division of Cardiology, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Arthur Jeremy Willsey
- Department of Psychiatry and Behavioral Sciences, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Kathleen M Fisch
- Center for Computational Biology & Bioinformatics, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Trey Ideker
- Division of Genetics, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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Ledford HA, Ren L, Thai PN, Park S, Timofeyev V, Sirish P, Xu W, Emigh AM, Priest JR, Perez MV, Ashley EA, Yarov-Yarovoy V, Yamoah EN, Zhang XD, Chiamvimonvat N. Disruption of protein quality control of the human ether-à-go-go related gene K + channel results in profound long QT syndrome. Heart Rhythm 2021; 19:281-292. [PMID: 34634443 DOI: 10.1016/j.hrthm.2021.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 09/20/2021] [Accepted: 10/04/2021] [Indexed: 11/04/2022]
Abstract
BACKGROUND Long QT syndrome (LQTS) is a hereditary disease that predisposes patients to life-threatening cardiac arrhythmias and sudden cardiac death. Our previous study of the human ether-à-go-go related gene (hERG)-encoded K+ channel (Kv11.1) supports an association between hERG and RING finger protein 207 (RNF207) variants in aggravating the onset and severity of LQTS, specifically T613M hERG (hERGT613M) and RNF207 frameshift (RNF207G603fs) mutations. However, the underlying mechanistic underpinning remains unknown. OBJECTIVE The purpose of the present study was to test the role of RNF207 in the function of hERG-encoded K+ channel subunits. METHODS Whole-cell patch-clamp experiments were performed in human embryonic kidney (HEK 293) cells and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) together with immunofluorescent confocal and high resolution microscopy, auto-ubiquitinylation assays, and co-immunoprecipitation experiments to test the functional interactions between hERG and RNF207. RESULTS Here, we demonstrated that RNF207 serves as an E3 ubiquitin ligase and targets misfolded hERGT613M proteins for degradation. RNF207G603fs exhibits decreased activity and hinders the normal degradation pathway; this increases the levels of hERGT613M subunits and their dominant-negative effect on the wild-type subunits, ultimately resulting in decreased current density. Similar findings are shown for hERGA614V, a known dominant-negative mutant subunit. Finally, the presence of RNF207G603fs with hERGT613M results in significantly prolonged action potential durations and reduced hERG current in human-induced pluripotent stem cell-derived cardiomyocytes. CONCLUSION Our study establishes RNF207 as an interacting protein serving as a ubiquitin ligase for hERG-encoded K+ channel subunits. Normal function of RNF207 is critical for the quality control of hERG subunits and consequently cardiac repolarization. Moreover, our study provides evidence for protein quality control as a new paradigm in life-threatening cardiac arrhythmias in patients with LQTS.
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Affiliation(s)
- Hannah A Ledford
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California
| | - Lu Ren
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California
| | - Phung N Thai
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California
| | - Seojin Park
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California; Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, Nevada
| | - Valeriy Timofeyev
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California
| | - Padmini Sirish
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California; Department of Veterans Affairs, Northern California Health Care System, Mather, California
| | - Wilson Xu
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California
| | - Aiyana M Emigh
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, California
| | - James R Priest
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, California
| | - Marco V Perez
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, California
| | - Euan A Ashley
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, California
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, California
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, Nevada
| | - Xiao-Dong Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California; Department of Veterans Affairs, Northern California Health Care System, Mather, California
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, California; Department of Veterans Affairs, Northern California Health Care System, Mather, California.
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Affiliation(s)
- Jitae A Kim
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Mihail G Chelu
- Section of Cardiology, Baylor College of Medicine, Houston, Texas
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12
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Saleem S, Kannan RR. Zebrafish: A Promising Real-Time Model System for Nanotechnology-Mediated Neurospecific Drug Delivery. NANOSCALE RESEARCH LETTERS 2021; 16:135. [PMID: 34424426 PMCID: PMC8382796 DOI: 10.1186/s11671-021-03592-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 08/15/2021] [Indexed: 06/13/2023]
Abstract
Delivering drugs to the brain has always remained a challenge for the research community and physicians. The blood-brain barrier (BBB) acts as a major hurdle for delivering drugs to specific parts of the brain and the central nervous system. It is physiologically comprised of complex network of capillaries to protect the brain from any invasive agents or foreign particles. Therefore, there is an absolute need for understanding of the BBB for successful therapeutic interventions. Recent research indicates the strong emergence of zebrafish as a model for assessing the permeability of the BBB, which is highly conserved in its structure and function between the zebrafish and mammals. The zebrafish model system offers a plethora of advantages including easy maintenance, high fecundity and transparency of embryos and larvae. Therefore, it has the potential to be developed as a model for analysing and elucidating the permeability of BBB to novel permeation technologies with neurospecificity. Nanotechnology has now become a focus area within the industrial and research community for delivering drugs to the brain. Nanoparticles are being developed with increased efficiency and accuracy for overcoming the BBB and delivering neurospecific drugs to the brain. The zebrafish stands as an excellent model system to assess nanoparticle biocompatibility and toxicity. Hence, the zebrafish model is indispensable for the discovery or development of novel technologies for neurospecific drug delivery and potential therapies for brain diseases.
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Affiliation(s)
- Suraiya Saleem
- Neuroscience Lab, Centre for Molecular and Nanomedical Sciences, Centre for Nanoscience and Nanotechnology, School of Bio and Chemical Engineering, Sathyabama Institute of Science and Technology (Deemed to be University), Jeppiaar Nagar, Rajiv Gandhi Salai, Chennai, Tamil Nadu, 600119, India
| | - Rajaretinam Rajesh Kannan
- Neuroscience Lab, Centre for Molecular and Nanomedical Sciences, Centre for Nanoscience and Nanotechnology, School of Bio and Chemical Engineering, Sathyabama Institute of Science and Technology (Deemed to be University), Jeppiaar Nagar, Rajiv Gandhi Salai, Chennai, Tamil Nadu, 600119, India.
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Iqbal S, Fayyaz SM, Saeed Y, Aqeel M. Loperamide-induced cardiotoxicity: a case overlooked? BMJ Case Rep 2021; 14:14/7/e243325. [PMID: 34290024 DOI: 10.1136/bcr-2021-243325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
A young man presented to the emergency department with seizures and recurrent episodes of polymorphic ventricular tachycardia (PMVT)/torsades de pointes (TdP) requiring cardioversion and administration of intravenous magnesium. A battery of tests performed to identify a cause for his arrhythmias and seizures were all normal. A revisit of history with family revealed he had consumed over 100 tablets/day of loperamide for the past 1 year. A prolonged QT interval on his ECG raised concerns for long QT syndrome (LQTS) (congenital or acquired). Our patient was suspected to have loperamide-induced cardiotoxicity. TdP is a specific PMVT that occurs with a prolonged QT interval and is usually drug-induced. Less frequently, congenital LQTS may be implicated. With supportive care, including mechanical ventilation, vasopressors and temporary transvenous overdrive pacing, our patient recovered completely. We describe the importance of a systematic and time-sensitive approach to diagnosing critical illness. Loperamide overdose may cause QT prolongation, life-threatening arrhythmias/cardiogenic shock, or cardiac arrest. Seizures/epilepsy may also be a manifestation in young patients. There is a substantial need to revisit the safety of over-the-counter medications and increasing awareness of manifestations of drug overdose.
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Affiliation(s)
- Sameen Iqbal
- Section of Cardiology, Department of Medicine, The Aga Khan University, Karachi, Pakistan
| | - Sidra Malik Fayyaz
- Section of Pulmonology & Critical Care Medicine, Department of Medicine, The Aga Khan University, Karachi, Pakistan
| | - Yawer Saeed
- Section of Cardiology, Department of Medicine, The Aga Khan University, Karachi, Pakistan
| | - Masooma Aqeel
- Section of Pulmonology & Critical Care Medicine, Department of Medicine, The Aga Khan University, Karachi, Pakistan
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Villafane J, Miller JR, Glickstein J, Johnson JN, Wagner J, Snyder CS, Filina T, Pomeroy SL, Sexson-Tejtel SK, Haxel C, Gottlieb J, Eghtesady P, Chowdhury D. Loss of Consciousness in the Young Child. Pediatr Cardiol 2021; 42:234-254. [PMID: 33388850 DOI: 10.1007/s00246-020-02498-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 11/07/2020] [Indexed: 01/03/2023]
Abstract
In the very young child (less than eight years of age), transient loss of consciousness represents a diagnostic and management dilemma for clinicians. While most commonly benign, syncope may be due to cardiac dysfunction which can be life-threatening. It can be secondary to an underlying ion channelopathy, cardiac inflammation, cardiac ischemia, congenital heart disease, cardiomyopathy, or pulmonary hypertension. Patients with genetic disorders require careful evaluation for a cardiac cause of syncope. Among the noncardiac causes, vasovagal syncope is the most common etiology. Breath-holding spells are commonly seen in this age group. Other causes of transient loss of consciousness include seizures, neurovascular pathology, head trauma, psychogenic pseudosyncope, and factitious disorder imposed on another and other forms of child abuse. A detailed social, present, past medical, and family medical history is important when evaluating loss of consciousness in the very young. Concerning characteristics of syncope include lack of prodromal symptoms, no preceding postural changes or occurring in a supine position, after exertion or a loud noise. A family history of sudden unexplained death, ion channelopathy, cardiomyopathy, or congenital deafness merits further evaluation. Due to inherent challenges in diagnosis at this age, often there is a lower threshold for referral to a specialist.
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Affiliation(s)
- Juan Villafane
- Department of Pediatrics, University of Cincinnati and Cincinnati Children's Hospital, Cincinnati, OH, USA. .,Department of Pediatrics, 743 East Broadway, Suite 300, Louisville, KY, 40202, USA.
| | - Jacob R Miller
- Department of Surgery, Division of Cardiothoracic Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | - Julie Glickstein
- Department of Pediatrics, Columbia University Medical Center, New York-Presbyterian Hospital, New York, NY, USA
| | - Jonathan N Johnson
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA
| | - Jonathan Wagner
- Department of Pediatrics, University of Missouri-Kansas City School of Medicine, Kansas City, MO, USA
| | - Chris S Snyder
- Congenital Heart Collaborative, Rainbow Babies and Children's Hospital, Case Western University, Cleveland, OH, USA
| | - Tatiana Filina
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Scott L Pomeroy
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Caitlin Haxel
- Department of Pediatrics, Children's Hospital of Colorado, University of Colorado School of Medicine, Aurora, CO, USA
| | | | - Pirooz Eghtesady
- Department of Surgery, Division of Cardiothoracic Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO, USA
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15
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Coleman M, Imundo JR, Cortez D, Cohen MH, Dhar P, Dalal PG. Torsades de Pointes During Myringotomy in a Child with Congenital Long QT Syndrome: A Case Report. AMERICAN JOURNAL OF CASE REPORTS 2020; 21:e925602. [PMID: 33056945 PMCID: PMC7571281 DOI: 10.12659/ajcr.925602] [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] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 09/07/2020] [Accepted: 07/31/2020] [Indexed: 01/08/2023]
Abstract
BACKGROUND Long QT syndrome (LQTS) is an arrhythmogenic heart condition that can be congenital or acquired. Prolonged ventricular repolarizations in individuals with the disorder can cause fatal arrhythmias. Abnormal functioning of cardiac ion channels leads to arrhythmias such as torsades de pointes (TdP) and may be triggered by stress or medications. Many medications used in the perioperative period are triggers for the arrythmia. CASE REPORT A 7-year-old patient with known congenital LQTS type 2 presented for bilateral myringotomy and tube placement. The patient was otherwise healthy and taking propranolol daily. Preoperative midazolam was administered for anxiolysis, and induction of anesthesia was uneventful. He sustained an episode of TdP immediately following general anesthetic induction after failure of an in situ automatic implantable cardioverter-defibrillator (AICD). External defibrillation succeeded, and the patient was stabilized in the Postanesthesia Recovery Unit before transfer to the Pediatric Intensive Care Unit. Interrogation of the AICD revealed several undelivered defibrillation attempts. A chest X-ray showed an area suggestive of an epicardial electrode fracture. The following day, the AICD was replaced with no arrythmias noted. The patient had an uneventful recovery. CONCLUSIONS In patients with a known history of LQTS, preparation and prevention are cornerstones of anesthesia care. Minimizing the use of triggering medications and emotional stress in the perioperative period, combined with ready equipment and medications to respond to arrythmias, are essential. In children, there is a greater chance of lead fracture and resulting device failure. Preoperative history of device function or interrogation of the AICD and possibly a chest X-ray are essential to ensure the integrity of the leads.
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Affiliation(s)
- Melissa Coleman
- Department of Anesthesiology and Perioperative Medicine, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, U.S.A
| | - Jason R. Imundo
- Department of Pediatrics, Division of Pediatric Cardiology, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, U.S.A
| | - Daniel Cortez
- Department of Pediatrics, Division of Pediatric Cardiology, University of Minnesota Masonic Children’s Hospital, Minneapolis, MN, U.S.A
| | - Mark H. Cohen
- Department of Pediatrics, Division of Pediatric Cardiology, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, U.S.A
| | - Padmani Dhar
- Department of Anesthesiology and Perioperative Medicine, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, U.S.A
| | - Priti G. Dalal
- Department of Anesthesiology and Perioperative Medicine, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, U.S.A
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16
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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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17
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Mazzone A, Strege PR, Gibbons SJ, Alcaino C, Joshi V, Haak AJ, Tschumperlin DJ, Bernard CE, Cima RR, Larson DW, Chua HK, Graham RP, El Refaey M, Mohler PJ, Hayashi Y, Ordog T, Calder S, Du P, Farrugia G, Beyder A. microRNA overexpression in slow transit constipation leads to reduced Na V1.5 current and altered smooth muscle contractility. Gut 2020; 69:868-876. [PMID: 31757880 PMCID: PMC7147984 DOI: 10.1136/gutjnl-2019-318747] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 10/16/2019] [Accepted: 11/06/2019] [Indexed: 12/13/2022]
Abstract
OBJECTIVE This study was designed to evaluate the roles of microRNAs (miRNAs) in slow transit constipation (STC). DESIGN All human tissue samples were from the muscularis externa of the colon. Expression of 372 miRNAs was examined in a discovery cohort of four patients with STC versus three age/sex-matched controls by a quantitative PCR array. Upregulated miRNAs were examined by quantitative reverse transcription qPCR (RT-qPCR) in a validation cohort of seven patients with STC and age/sex-matched controls. The effect of a highly differentially expressed miRNA on a custom human smooth muscle cell line was examined in vitro by RT-qPCR, electrophysiology, traction force microscopy, and ex vivo by lentiviral transduction in rat muscularis externa organotypic cultures. RESULTS The expression of 13 miRNAs was increased in STC samples. Of those miRNAs, four were predicted to target SCN5A, the gene that encodes the Na+ channel NaV1.5. The expression of SCN5A mRNA was decreased in STC samples. Let-7f significantly decreased Na+ current density in vitro in human smooth muscle cells. In rat muscularis externa organotypic cultures, overexpression of let-7f resulted in reduced frequency and amplitude of contraction. CONCLUSIONS A small group of miRNAs is upregulated in STC, and many of these miRNAs target the SCN5A-encoded Na+ channel NaV1.5. Within this set, a novel NaV1.5 regulator, let-7f, resulted in decreased NaV1.5 expression, current density and reduced motility of GI smooth muscle. These results suggest NaV1.5 and miRNAs as novel diagnostic and potential therapeutic targets in STC.
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Affiliation(s)
- Amelia Mazzone
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Peter R Strege
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Simon J Gibbons
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Constanza Alcaino
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Vikram Joshi
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Andrew J Haak
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Daniel J Tschumperlin
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Cheryl E Bernard
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Robert R Cima
- Department of Colon and Rectal Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - David W Larson
- Department of Colon and Rectal Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Heidi K Chua
- Department of Colon and Rectal Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Mona El Refaey
- Departments of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA,Department of Internal Medicine, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Peter J Mohler
- Departments of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Yujiro Hayashi
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Tamas Ordog
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Stefan Calder
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Gianrico Farrugia
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA .,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Arthur Beyder
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA .,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
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18
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Malik C, Ghosh S. Quinidine partially blocks mitochondrial voltage-dependent anion channel (VDAC). EUROPEAN BIOPHYSICS JOURNAL: EBJ 2020; 49:193-205. [DOI: 10.1007/s00249-020-01426-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 02/07/2023]
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19
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Görges M, Sherwin ED, Poznikoff AK, West NC, Brodie SM, Whyte SD. Effects of Dexmedetomidine on Myocardial Repolarization in Children Undergoing General Anesthesia: A Randomized Controlled Trial. Anesth Analg 2020; 129:1100-1108. [PMID: 30985379 DOI: 10.1213/ane.0000000000004135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Dexmedetomidine is a highly selective α2-adrenergic agonist, which is increasingly used in pediatric anesthesia and intensive care. Potential adverse effects that have not been rigorously evaluated in children include its effects on myocardial repolarization, which is important given that the drug is listed as a possible risk factor for torsades de pointes. We investigated the effect of 3 different doses of dexmedetomidine on myocardial repolarization and transmural dispersion in children undergoing elective surgery with total IV anesthesia. METHODS Sixty-four American Society of Anesthesiologists I-II children 3-10 years of age were randomized to receive dexmedetomidine 0.25 µg/kg, 0.5 µg/kg, 0.75 µg/kg, or 0 µg/kg (control), as a bolus administered over 60 seconds, after induction of anesthesia. Pre- and postintervention 12-lead electrocardiograms were recorded. The interval between the peak and the end of the electrocardiogram T wave (Tp-e; transmural dispersion) and heart rate-corrected QT intervals (myocardial repolarization) were measured by a pediatric electrophysiologist blinded to group allocation. Data were analyzed using an analysis of covariance regression model. The study was powered to detect a 25-millisecond difference in Tp-e. RESULTS Forty-eight children completed the study, with data analyzed from 12 participants per group. There were no instances of dysrhythmias. Tp-e values were unaffected by dexmedetomidine administration at any of the studied doses (F = 0.09; P = .96). Mean (99% CI) within-group differences were all <2 milliseconds (-5 to 8). Postintervention, corrected QT interval increased in the control group, but decreased in some dexmedetomidine groups (F = 7.23; P < .001), specifically the dexmedetomidine 0.5 and 0.75 µg/kg doses. Within groups, the mean (99% CI) differences between pre- and postintervention corrected QT interval were 12.4 milliseconds (-5.8 to 30.6) in the control group, -9.0 milliseconds (-24.9 to 6.9) for dexmedetomidine 0.25 µg/kg, -18.6 milliseconds (-33.7 to -3.5) for dexmedetomidine 0.5 µg/kg, and -14.1 milliseconds (-27.4 to -0.8) for dexmedetomidine 0.75 µg/kg. CONCLUSIONS Of the bolus doses of dexmedetomidine studied, none had an effect on Tp-e and the dexmedetomidine 0.5 and 0.75 µg/kg doses shortened corrected QT intervals when measured at 1 minute after dexmedetomidine bolus injection during total IV anesthesia. There is no evidence for an increased risk of torsades de pointes in this context.
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Affiliation(s)
- Matthias Görges
- From the Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada.,Research Institute, British Columbia Children's Hospital, Vancouver, British Columbia, Canada
| | | | - Andrew K Poznikoff
- From the Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Pediatric Anesthesia, British Columbia Children's Hospital, Vancouver, British Columbia, Canada
| | - Nicholas C West
- From the Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sonia M Brodie
- From the Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Simon D Whyte
- From the Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada.,Research Institute, British Columbia Children's Hospital, Vancouver, British Columbia, Canada.,Department of Pediatric Anesthesia, British Columbia Children's Hospital, Vancouver, British Columbia, Canada
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20
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Strano S, Toni D, Ammirati F, Sanna T, Tomaino M, Brignole M, Mazza A, Nguyen BL, Di Bonaventura C, Ricci RP, Boriani G. Neuro-arrhythmology: a challenging field of action and research: a review from the Task Force of Neuro-arrhythmology of Italian Association of Arrhythmias and Cardiac Pacing. J Cardiovasc Med (Hagerstown) 2020; 20:731-744. [PMID: 31567632 DOI: 10.2459/jcm.0000000000000866] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
: There is a growing interest in the study of the mechanisms of heart and brain interactions with the aim to improve the management of high-impact cardiac rhythm disorders, first of all atrial fibrillation. However, there are several topics to which the scientific interests of cardiologists and neurologists converge constituting the basis for enhancing the development of neuro-arrhythmology. This multidisciplinary field should cover a wide spectrum of diseases, even beyond the classical framework corresponding to stroke and atrial fibrillation and include the complex issues of seizures as well as loss of consciousness and syncope. The implications of a more focused interaction between neurologists and cardiologists in the field of neuro-arrhythmology should include in perspective the institution of research networks specifically devoted to investigate 'from bench to bedside' the complex pathophysiological links of the abovementioned diseases, with involvement of scientists in the field of biochemistry, genetics, molecular medicine, physiology, pathology and bioengineering. An investment in the field could have important implications in the perspectives of a more personalized approach to patients and diseases, in the context of 'precision'medicine. Large datasets and electronic medical records, with the approach typical of 'big data' could enhance the possibility of new findings with potentially important clinical implications. Finally, the interaction between neurologists and cardiologists involved in arrythmia management should have some organizational implications, with new models of healthcare delivery based on multidisciplinary assistance, similarly to that applied in the case of syncope units.
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Affiliation(s)
| | - Danilo Toni
- Emergency Department Stroke Unit, Department of Human Neurosciences, Sapienza University of Rome
| | | | - Tommaso Sanna
- Fondazione Policlinico A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Institute of Cardiology, Rome
| | - Marco Tomaino
- Department of Cardiology, Ospedale di Bolzano, Bolzano
| | - Michele Brignole
- Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna
| | - Andrea Mazza
- Cardiology Division, Santa Maria della Stella Hospital, Orvieto
| | | | | | | | - Giuseppe Boriani
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena University Hospital, Modena, Italy
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21
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Annachhatre AS. Intraoperative sudden cardiac death in pediatric patients - Calamity yet to overcome? Ann Card Anaesth 2019; 22:213-214. [PMID: 30971607 PMCID: PMC6489397 DOI: 10.4103/aca.aca_90_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Ajita Suhrid Annachhatre
- Department of Cardiac Anaesthesiology, MGM Medical College and MCRI, Aurangabad, Maharashtra, India
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22
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Savoji H, Mohammadi MH, Rafatian N, Toroghi MK, Wang EY, Zhao Y, Korolj A, Ahadian S, Radisic M. Cardiovascular disease models: A game changing paradigm in drug discovery and screening. Biomaterials 2019; 198:3-26. [PMID: 30343824 PMCID: PMC6397087 DOI: 10.1016/j.biomaterials.2018.09.036] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/11/2018] [Accepted: 09/22/2018] [Indexed: 02/06/2023]
Abstract
Cardiovascular disease is the leading cause of death worldwide. Although investment in drug discovery and development has been sky-rocketing, the number of approved drugs has been declining. Cardiovascular toxicity due to therapeutic drug use claims the highest incidence and severity of adverse drug reactions in late-stage clinical development. Therefore, to address this issue, new, additional, replacement and combinatorial approaches are needed to fill the gap in effective drug discovery and screening. The motivation for developing accurate, predictive models is twofold: first, to study and discover new treatments for cardiac pathologies which are leading in worldwide morbidity and mortality rates; and second, to screen for adverse drug reactions on the heart, a primary risk in drug development. In addition to in vivo animal models, in vitro and in silico models have been recently proposed to mimic the physiological conditions of heart and vasculature. Here, we describe current in vitro, in vivo, and in silico platforms for modelling healthy and pathological cardiac tissues and their advantages and disadvantages for drug screening and discovery applications. We review the pathophysiology and the underlying pathways of different cardiac diseases, as well as the new tools being developed to facilitate their study. We finally suggest a roadmap for employing these non-animal platforms in assessing drug cardiotoxicity and safety.
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Affiliation(s)
- Houman Savoji
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 170 College St, Toronto, Ontario, M5S 3G9, Canada; Toronto General Research Institute, University Health Network, University of Toronto, 200 Elizabeth St, Toronto, Ontario, M5G 2C4, Canada
| | - Mohammad Hossein Mohammadi
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 170 College St, Toronto, Ontario, M5S 3G9, Canada; Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, Ontario, M5S 3E5, Canada; Toronto General Research Institute, University Health Network, University of Toronto, 200 Elizabeth St, Toronto, Ontario, M5G 2C4, Canada
| | - Naimeh Rafatian
- Toronto General Research Institute, University Health Network, University of Toronto, 200 Elizabeth St, Toronto, Ontario, M5G 2C4, Canada
| | - Masood Khaksar Toroghi
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, Ontario, M5S 3E5, Canada
| | - Erika Yan Wang
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 170 College St, Toronto, Ontario, M5S 3G9, Canada
| | - Yimu Zhao
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 170 College St, Toronto, Ontario, M5S 3G9, Canada; Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, Ontario, M5S 3E5, Canada
| | - Anastasia Korolj
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 170 College St, Toronto, Ontario, M5S 3G9, Canada; Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, Ontario, M5S 3E5, Canada
| | - Samad Ahadian
- Toronto General Research Institute, University Health Network, University of Toronto, 200 Elizabeth St, Toronto, Ontario, M5G 2C4, Canada
| | - Milica Radisic
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 170 College St, Toronto, Ontario, M5S 3G9, Canada; Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St, Toronto, Ontario, M5S 3E5, Canada; Toronto General Research Institute, University Health Network, University of Toronto, 200 Elizabeth St, Toronto, Ontario, M5G 2C4, Canada.
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23
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Gauvin DV, Zimmermann ZJ, Yoder J, Harter M, Holdsworth D, Kilgus Q, May J, Dalton J, Baird TJ. A predictive index of biomarkers for ictogenesis from tier I safety pharmacology testing that may warrant tier II EEG studies. J Pharmacol Toxicol Methods 2018; 94:50-63. [PMID: 29751085 DOI: 10.1016/j.vascn.2018.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 04/25/2018] [Accepted: 05/03/2018] [Indexed: 12/20/2022]
Abstract
Three significant contributions to the field of safety pharmacology were recently published detailing the use of electroencephalography (EEG) by telemetry in a critical role in the successful evaluation of a compound during drug development (1] Authier, Delatte, Kallman, Stevens & Markgraf; JPTM 2016; 81:274-285; 2] Accardi, Pugsley, Forster, Troncy, Huang & Authier; JPTM; 81: 47-59; 3] Bassett, Troncy, Pouliot, Paquette, Ascaha, & Authier; JPTM 2016; 70: 230-240). These authors present a convincing case for monitoring neocortical biopotential waveforms (EEG, ECoG, etc) during preclinical toxicology studies as an opportunity for early identification of a central nervous system (CNS) risk during Investigational New Drug (IND) Enabling Studies. This review is about "ictogenesis" not "epileptogenesis". It is intended to characterize overt behavioral and physiological changes suggestive of drug-induced neurotoxicity/ictogenesis in experimental animals during Tier 1 safety pharmacology testing, prior to first dose administration in man. It is the presence of these predictive or comorbid biomarkers expressed during the requisite conduct of daily clinical or cage side observations, and in early ICH S7A Tier I CNS, pulmonary and cardiovascular safety study designs that should initiate an early conversation regarding Tier II inclusion of EEG monitoring. We conclude that there is no single definitive clinical marker for seizure liability but plasma exposures might add to set proper safety margins when clinical convulsions are observed. Even the observation of a study-related full tonic-clonic convulsion does not establish solid ground to require the financial and temporal investment of a full EEG study under the current regulatory standards. PREFATORY NOTE For purposes of this review, we have adopted the FDA term "sponsor" as it refers to any person who takes the responsibility for and initiates a nonclinical investigations of new molecular entities; FDA uses the term "sponsor" primarily in relation to investigational new drug application submissions.
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Affiliation(s)
- David V Gauvin
- Neurobehavioral Science and MPI Research (A Charles Rivers Company), Mattawan, MI, United States.
| | - Zachary J Zimmermann
- Neurobehavioral Science and MPI Research (A Charles Rivers Company), Mattawan, MI, United States
| | - Joshua Yoder
- Neurobehavioral Science and MPI Research (A Charles Rivers Company), Mattawan, MI, United States
| | - Marci Harter
- Safety Pharmacology, MPI Research (A Charles Rivers Company), Mattawan, MI, United States
| | - David Holdsworth
- Safety Pharmacology, MPI Research (A Charles Rivers Company), Mattawan, MI, United States
| | - Quinn Kilgus
- Safety Pharmacology, MPI Research (A Charles Rivers Company), Mattawan, MI, United States
| | - Jonelle May
- Safety Pharmacology, MPI Research (A Charles Rivers Company), Mattawan, MI, United States
| | - Jill Dalton
- Safety Pharmacology, MPI Research (A Charles Rivers Company), Mattawan, MI, United States
| | - Theodore J Baird
- Drug Safety Assessment, MPI Research (A Charles Rivers Company), Mattawan, MI, United States
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24
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Strege PR, Mazzone A, Bernard CE, Neshatian L, Gibbons SJ, Saito YA, Tester DJ, Calvert ML, Mayer EA, Chang L, Ackerman MJ, Beyder A, Farrugia G. Irritable bowel syndrome patients have SCN5A channelopathies that lead to decreased Na V1.5 current and mechanosensitivity. Am J Physiol Gastrointest Liver Physiol 2018; 314:G494-G503. [PMID: 29167113 PMCID: PMC5966747 DOI: 10.1152/ajpgi.00016.2017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The SCN5A-encoded voltage-gated mechanosensitive Na+ channel NaV1.5 is expressed in human gastrointestinal smooth muscle cells and interstitial cells of Cajal. NaV1.5 contributes to smooth muscle electrical slow waves and mechanical sensitivity. In predominantly Caucasian irritable bowel syndrome (IBS) patient cohorts, 2-3% of patients have SCN5A missense mutations that alter NaV1.5 function and may contribute to IBS pathophysiology. In this study we examined a racially and ethnically diverse cohort of IBS patients for SCN5A missense mutations, compared them with IBS-negative controls, and determined the resulting NaV1.5 voltage-dependent and mechanosensitive properties. All SCN5A exons were sequenced from somatic DNA of 252 Rome III IBS patients with diverse ethnic and racial backgrounds. Missense mutations were introduced into wild-type SCN5A by site-directed mutagenesis and cotransfected with green fluorescent protein into HEK-293 cells. NaV1.5 voltage-dependent and mechanosensitive functions were studied by whole cell electrophysiology with and without shear force. Five of 252 (2.0%) IBS patients had six rare SCN5A mutations that were absent in 377 IBS-negative controls. Six of six (100%) IBS-associated NaV1.5 mutations had voltage-dependent gating abnormalities [current density reduction (R225W, R433C, R986Q, and F1293S) and altered voltage dependence (R225W, R433C, R986Q, G1037V, and F1293S)], and at least one kinetic parameter was altered in all mutations. Four of six (67%) IBS-associated SCN5A mutations (R225W, R433C, R986Q, and F1293S) resulted in altered NaV1.5 mechanosensitivity. In this racially and ethnically diverse cohort of IBS patients, we show that 2% of IBS patients harbor SCN5A mutations that are absent in IBS-negative controls and result in NaV1.5 channels with abnormal voltage-dependent and mechanosensitive function. NEW & NOTEWORTHY The voltage-gated Na+ channel NaV1.5 contributes to smooth muscle physiology and electrical slow waves. In a racially and ethnically mixed irritable bowel syndrome cohort, 2% had mutations in the NaV1.5 gene SCN5A. These mutations were absent in irritable bowel syndrome-negative controls. Most mutant NaV1.5 channels were loss of function in voltage dependence or mechanosensitivity.
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Affiliation(s)
- Peter R. Strege
- 1Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Amelia Mazzone
- 1Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Cheryl E. Bernard
- 1Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Leila Neshatian
- 1Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Simon J. Gibbons
- 1Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Yuri A. Saito
- 1Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - David J. Tester
- 2Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Melissa L. Calvert
- 2Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Emeran A. Mayer
- 3Oppenheimer Center for Neurobiology of Stress and Resilience, Division of Digestive Diseases, University of California Los Angeles, Los Angeles, California
| | - Lin Chang
- 3Oppenheimer Center for Neurobiology of Stress and Resilience, Division of Digestive Diseases, University of California Los Angeles, Los Angeles, California
| | - Michael J. Ackerman
- 2Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Arthur Beyder
- 1Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Gianrico Farrugia
- 1Enteric NeuroScience Program, Division of Gastroenterology and Hepatology, Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
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25
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Conant G, Lai BFL, Lu RXZ, Korolj A, Wang EY, Radisic M. High-Content Assessment of Cardiac Function Using Heart-on-a-Chip Devices as Drug Screening Model. Stem Cell Rev Rep 2018; 13:335-346. [PMID: 28429185 DOI: 10.1007/s12015-017-9736-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Drug discovery and development continues to be a challenge to the pharmaceutical industry despite great advances in cell and molecular biology that allow for the design of better targeted therapeutics. Many potential drug compounds fail during the clinical trial due to inefficacy and toxicity that were not predicted during preclinical stages. The fundamental problem lies with the use of traditional drug screening models that still largely rely on the use of cell lines or animal cell monolayers, which leads to lack of predictive power of human tissue and organ response to the drug candidates. More physiologically relevant systems are therefore critical in relieving the burden of high failure rates. Emerging knowledge and techniques in tissue engineering and microfabrication have enabled the development of micro-engineered systems - collectively known as organs-on-chips - that may lead to a paradigm shift in preclinical drug screening assays. In this review we explore the technological advances and challenges in the development of heart-on-a-chip models, by addressing current assessment methods for drug-induced cardiotoxicity and providing a perspective on the modifications that should be implemented to realize the full potential of this system.
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Affiliation(s)
- Genevieve Conant
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Benjamin Fook Lun Lai
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Rick Xing Ze Lu
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Anastasia Korolj
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Erika Yan Wang
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Milica Radisic
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada.
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada.
- Toronto General Research Institute, Toronto, ON, Canada.
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26
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Kojima A, Shikata F, Okamura T, Higaki T, Ohno S, Horie M, Uchita S, Kawanishi Y, Namiguchi K, Yasugi T, Izutani H. Refractory ventricular fibrillations after surgical repair of atrial septal defects in a patient with CACNA1C gene mutation - case report. J Cardiothorac Surg 2017; 12:118. [PMID: 29258620 PMCID: PMC5735880 DOI: 10.1186/s13019-017-0683-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 12/07/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Congenital long QT syndrome (LQTS) can cause ventricular arrhythmic events with syncope and sudden death resulting from malignant torsades de pointes (TdP) followed by ventricular fibrillations (VFs). However, the syndrome is often overlooked prior to the development of arrhythmic events in patients with congenital heart diseases demonstrating right bundle branch block on electrocardiogram (ECG). We present a case of an adult patient with congenital heart disease who developed VFs postoperatively, potentially due to his mutation in a LQTS related gene, which was not identified on preoperative assessment due to incomplete evaluation of his family history. CASE PRESENTATION A 64-year-old man was diagnosed as having multiple atrial septal defects. He presented with no symptoms of heart failure. His preoperative ECG showed complete right bundle branch block (CRBBB) with a corrected QT interval time of 478 ms. He underwent open-heart surgery to close the defects through median sternotomy access. Three hours after the operation, he developed multiple events of TdP and VFs in the intensive care unit. Cardiopulmonary resuscitation and multiple cardioversions were attempted for his repetitive TdP and VFs. He eventually reverted to sinus rhythm, and intravenous beta-blocker was administered to maintain the sinus rhythm. After this event, his family history was reviewed, and it was confirmed that his daughter and grandson had a medical history of arrhythmia. A genetic test confirmed that he had a missense mutation in CACNA1C, p.K1580 T, which is the cause for type 8. CONCLUSIONS This case highlights the importance of paying attention to other ECG findings in patients with CRBBB, which can mask prolonged QT intervals.
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Affiliation(s)
- Ai Kojima
- Department of Cardiovascular Surgery, Ehime University, Shitsukawa, Toon, Ehime, 7910295, Japan
| | - Fumiaki Shikata
- Department of Cardiovascular Surgery, Ehime University, Shitsukawa, Toon, Ehime, 7910295, Japan. .,Department of Cardiothoracic Surgery, St Vincent's Hospital, Sydney, NSW, Australia.
| | - Toru Okamura
- Department of Cardiovascular Surgery, Ehime University, Shitsukawa, Toon, Ehime, 7910295, Japan
| | - Takashi Higaki
- Department of Pediatric Cardiology, Children's Medical Center, Ehime University, Ehime, Japan
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Shunji Uchita
- Department of Cardiovascular Surgery, Ehime University, Shitsukawa, Toon, Ehime, 7910295, Japan
| | - Yujiro Kawanishi
- Department of Cardiovascular Surgery, Ehime University, Shitsukawa, Toon, Ehime, 7910295, Japan.,Department of Cardiothoracic Surgery, St Vincent's Hospital, Sydney, NSW, Australia
| | - Kenji Namiguchi
- Department of Cardiovascular Surgery, Ehime University, Shitsukawa, Toon, Ehime, 7910295, Japan
| | - Takumi Yasugi
- Department of Cardiovascular Surgery, Ehime University, Shitsukawa, Toon, Ehime, 7910295, Japan
| | - Hironori Izutani
- Department of Cardiovascular Surgery, Ehime University, Shitsukawa, Toon, Ehime, 7910295, Japan
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27
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Reentry via high-frequency pacing in a mathematical model for human-ventricular cardiac tissue with a localized fibrotic region. Sci Rep 2017; 7:15350. [PMID: 29127361 PMCID: PMC5681702 DOI: 10.1038/s41598-017-15735-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 10/02/2017] [Indexed: 11/08/2022] Open
Abstract
Localized heterogeneities, caused by the regional proliferation of fibroblasts, occur in mammalian hearts because of diseases like myocardial infarction. Such fibroblast clumps can become sources of pathological reentrant activities, e.g., spiral or scroll waves of electrical activation in cardiac tissue. The occurrence of reentry in cardiac tissue with heterogeneities, such as fibroblast clumps, can depend on the frequency at which the medium is paced. Therefore, it is important to study the reentry-initiating potential of such fibroblast clumps at different frequencies of pacing. We investigate the arrhythmogenic effects of fibroblast clumps at high- and low-frequency pacing. We find that reentrant waves are induced in the medium more prominently at high-frequency pacing than with low-frequency pacing. We also study the other factors that affect the potential of fibroblast clumps to induce reentry in cardiac tissue. In particular, we show that the ability of a fibroblast clump to induce reentry depends on the size of the clump, the distribution and percentage of fibroblasts in the clump, and the excitability of the medium. We study the process of reentry in two-dimensional and a three-dimensional mathematical models for cardiac tissue.
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28
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O'Neal WT, Singleton MJ, Roberts JD, Tereshchenko LG, Sotoodehnia N, Chen LY, Marcus GM, Soliman EZ. Association Between QT-Interval Components and Sudden Cardiac Death: The ARIC Study (Atherosclerosis Risk in Communities). Circ Arrhythm Electrophysiol 2017; 10:CIRCEP.117.005485. [PMID: 29030380 DOI: 10.1161/circep.117.005485] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 08/18/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Several reports have demonstrated that prolongation of the QT interval is associated with sudden cardiac death (SCD). However, it is unknown whether any of the components within the QT interval are responsible for its association with SCD. METHODS AND RESULTS We examined the association of the individual QT-interval components (R-wave onset to R-peak, R-peak to R-wave end, ST-segment, T-wave onset to T-peak, and T-peak to T-wave end) with SCD in 12 241 participants (54±5.7 years; 26% black; 55% women) from the ARIC study (Atherosclerosis Risk in Communities). The QT interval and its components were measured at baseline (1987-1989) from 12-lead ECGs. SCD cases were adjudicated by a group of physicians through December 31, 2012. During a median follow-up of 23.6 years, a total of 346 cases of SCD were identified. Although prolongation of the QT interval was associated with a 49% increased risk of SCD (hazard ratio, 1.49; 95% confidence interval, 1.01-2.18), only the T-wave onset to T-peak component (per 1-SD increase: hazard ratio, 1.19; 95% confidence interval, 1.06-1.34) was associated with SCD and not any of the other components in separate models. When all of the QT-interval components were included in the same model, T-wave onset to T-peak remained the strongest predictor of SCD (per 1-SD increase: hazard ratio, 1.21; 95% confidence interval, 1.06-1.37). CONCLUSIONS The risk of SCD with the QT interval is driven by prolongation of the T-wave onset to T-peak component. This suggests that shifting the focus from the overall QT interval to its individual components will refine SCD prediction in the community.
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Affiliation(s)
- Wesley T O'Neal
- From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (W.T.O.); Division of Cardiology, Department of Medicine (M.J.S., E.Z.S.) and Department of Epidemiology and Prevention, Epidemiological Cardiology Research Center (E.Z.S.), Wake Forest School of Medicine, Winston-Salem, NC; Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, Western University, London, Ontario, Canada (J.D.R.); Knight Cardiovascular Institute, Oregon Health and Science University, Portland (L.G.T.); Division of Cardiology, Cardiovascular Health Research Unit, University of Washington, Seattle (N.S.); Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis (L.Y.C.); and Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, University of California San Francisco (G.M.M.).
| | - Matthew J Singleton
- From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (W.T.O.); Division of Cardiology, Department of Medicine (M.J.S., E.Z.S.) and Department of Epidemiology and Prevention, Epidemiological Cardiology Research Center (E.Z.S.), Wake Forest School of Medicine, Winston-Salem, NC; Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, Western University, London, Ontario, Canada (J.D.R.); Knight Cardiovascular Institute, Oregon Health and Science University, Portland (L.G.T.); Division of Cardiology, Cardiovascular Health Research Unit, University of Washington, Seattle (N.S.); Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis (L.Y.C.); and Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, University of California San Francisco (G.M.M.)
| | - Jason D Roberts
- From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (W.T.O.); Division of Cardiology, Department of Medicine (M.J.S., E.Z.S.) and Department of Epidemiology and Prevention, Epidemiological Cardiology Research Center (E.Z.S.), Wake Forest School of Medicine, Winston-Salem, NC; Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, Western University, London, Ontario, Canada (J.D.R.); Knight Cardiovascular Institute, Oregon Health and Science University, Portland (L.G.T.); Division of Cardiology, Cardiovascular Health Research Unit, University of Washington, Seattle (N.S.); Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis (L.Y.C.); and Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, University of California San Francisco (G.M.M.)
| | - Larisa G Tereshchenko
- From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (W.T.O.); Division of Cardiology, Department of Medicine (M.J.S., E.Z.S.) and Department of Epidemiology and Prevention, Epidemiological Cardiology Research Center (E.Z.S.), Wake Forest School of Medicine, Winston-Salem, NC; Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, Western University, London, Ontario, Canada (J.D.R.); Knight Cardiovascular Institute, Oregon Health and Science University, Portland (L.G.T.); Division of Cardiology, Cardiovascular Health Research Unit, University of Washington, Seattle (N.S.); Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis (L.Y.C.); and Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, University of California San Francisco (G.M.M.)
| | - Nona Sotoodehnia
- From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (W.T.O.); Division of Cardiology, Department of Medicine (M.J.S., E.Z.S.) and Department of Epidemiology and Prevention, Epidemiological Cardiology Research Center (E.Z.S.), Wake Forest School of Medicine, Winston-Salem, NC; Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, Western University, London, Ontario, Canada (J.D.R.); Knight Cardiovascular Institute, Oregon Health and Science University, Portland (L.G.T.); Division of Cardiology, Cardiovascular Health Research Unit, University of Washington, Seattle (N.S.); Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis (L.Y.C.); and Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, University of California San Francisco (G.M.M.)
| | - Lin Y Chen
- From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (W.T.O.); Division of Cardiology, Department of Medicine (M.J.S., E.Z.S.) and Department of Epidemiology and Prevention, Epidemiological Cardiology Research Center (E.Z.S.), Wake Forest School of Medicine, Winston-Salem, NC; Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, Western University, London, Ontario, Canada (J.D.R.); Knight Cardiovascular Institute, Oregon Health and Science University, Portland (L.G.T.); Division of Cardiology, Cardiovascular Health Research Unit, University of Washington, Seattle (N.S.); Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis (L.Y.C.); and Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, University of California San Francisco (G.M.M.)
| | - Gregory M Marcus
- From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (W.T.O.); Division of Cardiology, Department of Medicine (M.J.S., E.Z.S.) and Department of Epidemiology and Prevention, Epidemiological Cardiology Research Center (E.Z.S.), Wake Forest School of Medicine, Winston-Salem, NC; Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, Western University, London, Ontario, Canada (J.D.R.); Knight Cardiovascular Institute, Oregon Health and Science University, Portland (L.G.T.); Division of Cardiology, Cardiovascular Health Research Unit, University of Washington, Seattle (N.S.); Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis (L.Y.C.); and Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, University of California San Francisco (G.M.M.)
| | - Elsayed Z Soliman
- From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (W.T.O.); Division of Cardiology, Department of Medicine (M.J.S., E.Z.S.) and Department of Epidemiology and Prevention, Epidemiological Cardiology Research Center (E.Z.S.), Wake Forest School of Medicine, Winston-Salem, NC; Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, Western University, London, Ontario, Canada (J.D.R.); Knight Cardiovascular Institute, Oregon Health and Science University, Portland (L.G.T.); Division of Cardiology, Cardiovascular Health Research Unit, University of Washington, Seattle (N.S.); Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis (L.Y.C.); and Division of Cardiology, Department of Medicine, Section of Cardiac Electrophysiology, University of California San Francisco (G.M.M.)
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29
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Yu W, Jin H, Tang C, Du J, Zhang Z. Sulfur-containing gaseous signal molecules, ion channels and cardiovascular diseases. Br J Pharmacol 2017; 175:1114-1125. [PMID: 28430359 DOI: 10.1111/bph.13829] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/23/2017] [Accepted: 04/11/2017] [Indexed: 01/05/2023] Open
Abstract
Sulfur-containing gaseous signal molecules including hydrogen sulphide and sulfur dioxide were previously recognized as toxic gases. However, extensive studies have revealed that they can be generated in the cardiovascular system via a sulfur-containing amino acid metabolic pathway, and have an important role in cardiovascular physiology and pathophysiology. Ion channels are pore-forming membrane proteins present in the membrane of all biological cells; their functions include the establishment of a resting membrane potential and the control of action potentials and other electrical signals by conducting ions across the cell membrane. Evidence has now accumulated suggesting that the sulfur-containing gaseous signal molecules are important regulators of ion channels and transporters. The aims of this review are (1) to discuss the recent experimental evidences in the cardiovascular system regarding the regulatory effects of sulfur-containing gaseous signal molecules on a variety of ion channels, including ATP-sensitive potassium, calcium-activated potassium, voltage-gated potassium, L- and T-type calcium, transient receptor potential and chloride and sodium channels, and (2) to understand how the gaseous signal molecules affect ion channels and cardiovascular diseases. LINKED ARTICLES This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.
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Affiliation(s)
- Wen Yu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Hongfang Jin
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Chaoshu Tang
- Key Laboratory of Molecular Cardiology, Ministry of Education, Beijing, China
| | - Junbao Du
- Department of Pediatrics, Peking University First Hospital, Beijing, China.,Key Laboratory of Molecular Cardiology, Ministry of Education, Beijing, China
| | - Zhiren Zhang
- Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Harbin Medical University Cancer Hospital, Harbin, China
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30
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Madan N, Carvalho KS. Neurological Complications of Cardiac Disease. Semin Pediatr Neurol 2017; 24:3-13. [PMID: 28779863 DOI: 10.1016/j.spen.2017.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This article focuses on the complex interactions between the cardiovascular and neurologic systems. Initially, we focus on neurological complications in children with congenital heart disease both secondary to the underlying cardiac disease and complications of interventions. We later discuss diagnosis and management of common syncope syndromes with emphasis on vasovagal syncope. We also review the diagnosis, classification, and management of children and adolescents with postural orthostatic tachycardia syndrome. Lastly, we discuss long QT syndrome and sudden unexpected death in epilepsy (SUDEP), reviewing advances in genetics and current knowledge of pathophysiology of these conditions. This article attempts to provide an overview of these disorders with focus on pathophysiology, advances in molecular genetics, and current medical interventions.
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Affiliation(s)
- Nandini Madan
- From the Section of Cardiology, Department of Pediatrics, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA.
| | - Karen S Carvalho
- Section of Neurology, Department of Pediatrics, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA
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31
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Antoniou CK, Dilaveris P, Manolakou P, Galanakos S, Magkas N, Gatzoulis K, Tousoulis D. QT Prolongation and Malignant Arrhythmia: How Serious a Problem? Eur Cardiol 2017; 12:112-120. [PMID: 30416582 DOI: 10.15420/ecr.2017:16:1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
QT prolongation constitutes one of the most frequently encountered electrical disorders of the myocardium. This is due not only to the presence of several associated congenital syndrome but also, and mainly, due to the QT-prolonging effects of several acquired conditions, such as ischaemia and heart failure, as well as multiple medications from widely different categories. Propensity of repolarization disturbances to arrhythmia appears to be inherent in the function of and electrophysiology of the myocardium. In the present review the issue of QT prolongation will be addressed in terms of pathophysiology, arrhythmogenesis, treatment and risk stratification approaches. Although already discussed in literature, it is hoped that the mechanistic approach of the present review will assist in improved understanding of the underlying changes in electrophysiology, as well as the rationale for current diagnostic and therapeutic approaches.
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Affiliation(s)
| | | | - Panagiota Manolakou
- First Department of Cardiology, Korgialenion-Benakion/Hellenic Red Cross Hospital Athens, Greece
| | - Spyridon Galanakos
- First University Department of Cardiology, Hippokration Hospital Athens, Greece
| | - Nikolaos Magkas
- First University Department of Cardiology, Hippokration Hospital Athens, Greece
| | | | - Dimitrios Tousoulis
- First University Department of Cardiology, Hippokration Hospital Athens, Greece
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Ravindran K, Powell KL, Todaro M, O'Brien TJ. The pathophysiology of cardiac dysfunction in epilepsy. Epilepsy Res 2016; 127:19-29. [PMID: 27544485 DOI: 10.1016/j.eplepsyres.2016.08.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 08/07/2016] [Accepted: 08/10/2016] [Indexed: 11/15/2022]
Abstract
Alterations in cardiac electrophysiology are an established consequence of long-standing drug resistant epilepsy. Patients with chronic epilepsy display abnormalities in both sinoatrial node pacemaker current as well as ventricular repolarizing current that places them at a greater risk of developing life-threatening cardiac arrhythmias. The development of cardiac arrhythmias secondary to drug resistant epilepsy is believed to be a key mechanism underlying the phenomenon of Sudden Unexpected Death in EPilepsy (SUDEP). Though an increasing amount of studies examining both animal models and human patients have provided evidence that chronic epilepsy can detrimentally affect cardiac function, the underlying pathophysiology remains unclear. Recent work has shown the expression of several key cardiac ion channels to be altered in animal models of genetic and acquired epilepsies. This has led to the currently held paradigm that cardiac ion channel expression may be secondarily altered as a consequence of seizure activity-resulting in electrophysiological cardiac dysfunction. Furthermore, cortical autonomic dysfunction - resulting from seizure activity-has also been suggested to play a role, whereby seizure activity may indirectly influence cardiac function via altering centrally-mediated autonomic output to the heart. In this review, we discuss various cardiac dysrhythmias associated with seizure events-including tachycardia, bradycardia and QT prolongation, both ictally and inter-ictally, as well as the role of the autonomic nervous system. We further discuss key ion channels expressed in both the heart and the brain that have been shown to be altered in epilepsy and may be responsible for the development of cardiac dysrhythmias secondary to chronic epilepsy.
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Affiliation(s)
- Krishnan Ravindran
- Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia.
| | - Kim L Powell
- Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia
| | - Marian Todaro
- Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia
| | - Terence J O'Brien
- Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia.
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Schneider AE, Bos JM, Ackerman MJ. Effect of Left Cardiac Sympathetic Denervation on the Electromechanical Window in Patients with either Type 1 or Type 2 Long QT Syndrome: A Pilot Study. CONGENIT HEART DIS 2016; 11:437-443. [DOI: 10.1111/chd.12332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/13/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Andrew E. Schneider
- Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine; Mayo Clinic; Rochester Minn USA
| | - J. Martijn Bos
- Division of Cardiovascular Diseases, Department of Medicine; Mayo Clinic; Rochester Minn USA
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Mayo Clinic; Rochester Minn USA
| | - Michael J. Ackerman
- Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine; Mayo Clinic; Rochester Minn USA
- Division of Cardiovascular Diseases, Department of Medicine; Mayo Clinic; Rochester Minn USA
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Mayo Clinic; Rochester Minn USA
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Murray CI, Westhoff M, Eldstrom J, Thompson E, Emes R, Fedida D. Unnatural amino acid photo-crosslinking of the IKs channel complex demonstrates a KCNE1:KCNQ1 stoichiometry of up to 4:4. eLife 2016; 5. [PMID: 26802629 PMCID: PMC4807126 DOI: 10.7554/elife.11815] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 01/22/2016] [Indexed: 12/20/2022] Open
Abstract
Cardiac repolarization is determined in part by the slow delayed rectifier current (IKs), through the tetrameric voltage-gated ion channel, KCNQ1, and its β-subunit, KCNE1. The stoichiometry between α and β-subunits has been controversial with studies reporting either a strict 2 KCNE1:4 KCNQ1 or a variable ratio up to 4:4. We used IKs fusion proteins linking KCNE1 to one (EQ), two (EQQ) or four (EQQQQ) KCNQ1 subunits, to reproduce compulsory 4:4, 2:4 or 1:4 stoichiometries. Whole cell and single-channel recordings showed EQQ and EQQQQ to have increasingly hyperpolarized activation, reduced conductance, and shorter first latency of opening compared to EQ - all abolished by the addition of KCNE1. As well, using a UV-crosslinking unnatural amino acid in KCNE1, we found EQQQQ and EQQ crosslinking rates to be progressively slowed compared to KCNQ1, which demonstrates that no intrinsic mechanism limits the association of up to four β-subunits within the IKs complex. DOI:http://dx.doi.org/10.7554/eLife.11815.001 The membrane that surrounds heart muscle cells contains specialized channels that can open and close to control the movements of charged ions into and out of the cell. This ion flow generates the electrical signals that stimulate the heart muscle to contract for each heart beat. Different ion channels influence different steps in the initiation and termination of each electrical signal. For example, the IKs ion channel complex helps to return the cell to a resting state so the heart muscle can relax. This allows chambers of the heart to fill with blood before the next beat pumps blood throughout the body. Mutations that affect IKs cause serious heart conditions that affect heart rhythm, such as Long QT Syndrome. The IKs complex consists of channels that are each made of four copies of a protein called KCNQ1, through which potassium ions exit the cell. This channel opens in response to changes in the voltage across the cell membrane (known as the “membrane potential”). A small protein subunit called KCNE1 also makes up part of the complex, but it was not clear how many KCNE1 molecules combine with KCNQ1 to form a working channel complex. Several previous studies have reported two different results: that the KCNQ1 channel complex only exists with two KCNE1 molecules, or that the association is flexible, allowing the complex to contain up to four KCNE1 subunits. Murray et al. have now constructed IKs fusion channels out of different numbers of KCNQ1 and KCNE1 molecules to investigate how different KCNQ1:KCNE1 ratios affect how the channel works. Measuring the responses of these modified channels in mammalian cells revealed that channels with four KCNE1 subunits conducted ions better than channels with one or two KCNE1s. The channels containing fewer KCNE1s also opened at lower membrane potentials and after a shorter delay following a change in the membrane potential. Further experiments also supported the theory that up to four independent KCNE1 subunits may be easily added to the IKs ion channel complex. Murray et al. suggest that by being able to form channel complexes containing different numbers of KCNE1 subunits, cells can more flexibly control the rate at which ions flow out of the heart cells to tune the electrical signals that trigger each heart beat. The next challenges will be to determine the composition of the IKs channel complex in adult heart cells and to investigate how the complex might change with disease. DOI:http://dx.doi.org/10.7554/eLife.11815.002
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Affiliation(s)
- Christopher I Murray
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Maartje Westhoff
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Jodene Eldstrom
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Emely Thompson
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Robert Emes
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
| | - David Fedida
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
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Ackerman MJ. Genetic purgatory and the cardiac channelopathies: Exposing the variants of uncertain/unknown significance issue. Heart Rhythm 2015; 12:2325-31. [PMID: 26144349 DOI: 10.1016/j.hrthm.2015.07.002] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Indexed: 10/23/2022]
Abstract
Merriam-Webster's online dictionary defines purgatory as "an intermediate state after death for expiatory purification" or more specifically as "a place or state of punishment wherein according to Roman Catholic doctrine the souls of those who die in God׳s grace may make satisfaction for past sins and so become fit for heaven." Alternatively, it is defined as "a place or state of temporary suffering or misery." Either way, purgatory is a place where you are stuck, and you don't want to be stuck there. It is in this context that the term genetic purgatory is introduced. Genetic purgatory is a place where the genetic test-ordering physician and patients and their families are stuck when a variant of uncertain/unknown significance (VUS) has been elucidated. It is in this dark place where suffering and misery are occurring because of unenlightened handling of a VUS, which includes using the VUS for predictive genetic testing and making radical treatment recommendations based on the presence or absence of a so-called maybe mutation. Before one can escape from this miserable place, one must first recognize that one is stuck there. Hence, the purpose of this review article is to fully expose the VUS issue as it relates to the cardiac channelopathies and make the cardiologists/geneticists/genetic counselors who order such genetic tests believers in genetic purgatory. Only then can one meaningfully attempt to get out of that place and seek to promote a VUS to disease-causative mutation status or demote it to an utterly innocuous and irrelevant variant.
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Affiliation(s)
- Michael J Ackerman
- Departments of Medicine, Pediatrics, and Molecular Pharmacology & Experimental Therapeutics, Divisions of Cardiovascular Medicine, Pediatric Cardiology, and the Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota.
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Rohatgi RK, Bos JM, Ackerman MJ. Stimulant therapy in children with attention-deficit/hyperactivity disorder and concomitant long QT syndrome: A safe combination? Heart Rhythm 2015; 12:1807-12. [PMID: 25956966 DOI: 10.1016/j.hrthm.2015.04.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND Attention-deficit/hyperactivity disorder (ADHD) is prevalent in about 11% of children in the United States. As such, ADHD is expected to be present in patients with long QT syndrome (LQTS), a rare, potentially lethal but highly treatable cardiac channelopathy. ADHD-directed stimulant therapy is relatively contraindicated in patients with LQTS because of concern for LQTS-triggered events. OBJECTIVE The purpose of this study was to evaluate the ADHD-directed treatment, outcome, and frequency of LQTS-triggered events in patients with LQTS and concomitant ADHD. METHODS A retrospective electronic medical record review of 357 pediatric patients with LQTS evaluated between 1999 and 2014 was performed to determine the prevalence of concomitant ADHD and the incidence of LQTS-triggered events in patients with LQTS, with or without concomitant ADHD. RESULTS Overall, 28 patients (8%) were diagnosed with LQTS concomitant ADHD. There were no phenotypic differences between patients with LQTS and ADHD, and LQTS alone. ADHD-directed stimulant therapy was stopped or advised against in 19 patients (68%) at the time of first evaluation or after diagnosis. None of the 15 stimulant-treated patients experienced LQTS-triggered events in a combined 56 person-years of treatment. Perhaps paradoxically, there was a statistically lower LQTS-triggered event rate in the stimulant-treated ADHD group compared to the LQTS alone cohort. CONCLUSION Among patients with mild- to moderate-risk LQTS, we found a prevalence of ADHD similar to that in the general population, which can be treated effectively and safely with stimulant therapy. Physicians should find reassurance in the low adverse event rate and should weigh the potential effects of suboptimal treatment of ADHD with the theoretical proarrhythmic risk from stimulant medications.
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Affiliation(s)
- Ram K Rohatgi
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota
| | - J Martijn Bos
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Michael J Ackerman
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota,; Department of Medicine/Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota.
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Aromolaran AS, Subramanyam P, Chang DD, Kobertz WR, Colecraft HM. LQT1 mutations in KCNQ1 C-terminus assembly domain suppress IKs using different mechanisms. Cardiovasc Res 2014; 104:501-11. [PMID: 25344363 DOI: 10.1093/cvr/cvu231] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
AIMS Long QT syndrome 1 (LQT1) mutations in KCNQ1 that decrease cardiac IKs (slowly activating delayed rectifier K(+) current) underlie ventricular arrhythmias and sudden death. LQT1 mutations may suppress IKs by preventing KCNQ1 assembly, disrupting surface trafficking, or inhibiting gating. We investigated mechanisms underlying how three LQT1 mutations in KCNQ1 C-terminus assembly domain (R555H/G589D/L619M) decrease IKs in heterologous cells and cardiomyocytes. METHODS AND RESULTS In Chinese hamster ovary (CHO) cells, mutant KCNQ1 + KCNE1 channels either produced no currents (G589D/L619M) or displayed markedly reduced IKs with a right-shifted voltage-dependence of activation (R555H). When co-expressed with wild-type (wt) KCNQ1, the mutant KCNQ1s displayed varying intrinsic dominant-negative capacities that were affected by auxiliary KCNE1. All three mutant KCNQ1s assembled with wt KCNQ1 as determined by fluorescence resonance energy transfer (FRET). We developed an optical quantum dot labelling assay to measure channel surface density. G589D/R555H displayed substantial reductions in surface density, which were either partially (G589D) or fully (R555H) rescued by wt KCNQ1. Unexpectedly, L619M showed no trafficking defect. In adult rat cardiomyocytes, adenovirus-expressed homotetrameric G589D/L619M + KCNE1 channels yielded no currents, whereas R555H + KCNE1 produced diminished IKs with a right-shifted voltage-dependence of activation, mimicking observations in CHO cells. In contrast to heterologous cells, homotetrameric R555H channels showed no trafficking defect in cardiomyocytes. CONCLUSION Distinct LQT1 mutations in KCNQ1 assembly domain decrease IKs using unique combinations of biophysical and trafficking mechanisms. Functional deficits in IKs observed in heterologous cells are mostly, but not completely, recapitulated in adult rat cardiomyocytes. A 'methodological chain' combining approaches in heterologous cells and cardiomyocytes provides mechanistic insights that may help advance personalized therapy for LQT1 mutations.
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Affiliation(s)
- Ademuyiwa S Aromolaran
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, 504 Russ Berrie, New York, NY 10032, USA
| | - Prakash Subramanyam
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, 504 Russ Berrie, New York, NY 10032, USA
| | - Donald D Chang
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, 504 Russ Berrie, New York, NY 10032, USA
| | - William R Kobertz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School Worcester, MA 01605, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, 504 Russ Berrie, New York, NY 10032, USA
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Affiliation(s)
- Yuka Mizusawa
- The Heart Failure Research Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Arthur AM Wilde
- The Heart Failure Research Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam
- Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, King Abdulaziz University
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Capes DL, Goldschen-Ohm MP, Arcisio-Miranda M, Bezanilla F, Chanda B. Domain IV voltage-sensor movement is both sufficient and rate limiting for fast inactivation in sodium channels. ACTA ACUST UNITED AC 2013; 142:101-12. [PMID: 23858005 PMCID: PMC3727307 DOI: 10.1085/jgp.201310998] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Voltage-gated sodium channels are critical for the generation and propagation of electrical signals in most excitable cells. Activation of Na(+) channels initiates an action potential, and fast inactivation facilitates repolarization of the membrane by the outward K(+) current. Fast inactivation is also the main determinant of the refractory period between successive electrical impulses. Although the voltage sensor of domain IV (DIV) has been implicated in fast inactivation, it remains unclear whether the activation of DIV alone is sufficient for fast inactivation to occur. Here, we functionally neutralize each specific voltage sensor by mutating several critical arginines in the S4 segment to glutamines. We assess the individual role of each voltage-sensing domain in the voltage dependence and kinetics of fast inactivation upon its specific inhibition. We show that movement of the DIV voltage sensor is the rate-limiting step for both development and recovery from fast inactivation. Our data suggest that activation of the DIV voltage sensor alone is sufficient for fast inactivation to occur, and that activation of DIV before channel opening is the molecular mechanism for closed-state inactivation. We propose a kinetic model of sodium channel gating that can account for our major findings over a wide voltage range by postulating that DIV movement is both necessary and sufficient for fast inactivation.
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Affiliation(s)
- Deborah L Capes
- Department of Neuroscience, University of Wisconsin, Madison, Madison, WI 53706, USA
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Vahedi F, Diamant UB, Lundahl G, Bergqvist G, Gransberg L, Jensen SM, Bergfeldt L. Instability of repolarization in LQTS mutation carriers compared to healthy control subjects assessed by vectorcardiography. Heart Rhythm 2013; 10:1169-75. [PMID: 23643511 DOI: 10.1016/j.hrthm.2013.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Indexed: 11/18/2022]
Abstract
BACKGROUND Potassium channel dysfunction in congenital and acquired forms of long QT syndrome types 1 and 2 (LQT1 and LQT2) increases the beat-to-beat variability of the QT interval. OBJECTIVE To study about the little known variability (instability) of other aspects of ventricular repolarization (VR) in humans by using vectorcardiography. METHODS Beat-to-beat analysis was performed regarding vectorcardiography derived RR, QRS, and QT intervals, as well as T vector- and T vector loop-based parameters during 1-minute recordings of uninterrupted sinus rhythm at rest in 41 adult LQT1 (n = 31) and LQT2 (n = 10) mutation carriers and 41 age- and sex-matched control subjects. The short-term variability for each parameter, describing the mean orthogonal distance to the line of identity on the Poincaré plot, was calculated. RESULTS Mutation carriers showed significantly larger (by a factor 2) instability in most VR parameters compared to controls despite higher instantaneous heart rate variability (STVRR) in the control group. The longer the QT interval, the greater was its instability, and the instability of VR dispersion measures. CONCLUSIONS A greater instability of most aspects of VR already at rest seems to be a salient feature in both LQT1 and LQT2, which might pave the way for early afterdepolarizations and torsades de pointes ventricular tachycardia. In contrast, no signs of increased VR dispersion per se were observed in mutation carriers.
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Affiliation(s)
- Farzad Vahedi
- Department of Molecular and Clinical Medicine/Cardiology, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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Fazio G, Vernuccio F, Grutta G, Re GL. Drugs to be avoided in patients with long QT syndrome: Focus on the anaesthesiological management. World J Cardiol 2013; 5:87-93. [PMID: 23675554 PMCID: PMC3653016 DOI: 10.4330/wjc.v5.i4.87] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 03/05/2013] [Accepted: 03/29/2013] [Indexed: 02/06/2023] Open
Abstract
Long QT syndrome incidence is increasing in general population. A careful pre-, peri- and post-operative management is needed for patients with this syndrome because of the risk of Torsades de Pointes and malignant arrhythmias. The available data regarding prevention of lethal Torsades de Pointes during anesthesia in patients with long QT syndrome is scant and conflicting: only case reports and small case series with different outcomes have been published. Actually, there are no definitive guidelines on pre-, peri- and post-operative anesthetic management of congenital long QT syndrome. Our review focuses on anesthetic recommendations for patients diagnosed with congenital long QT syndrome furnishing some key points for preoperative optimization, intraoperative anesthetic agents and postoperative care plan, which could be the best for patients with c-long QT syndrome who undergo surgery.
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Mahida S, Hogarth AJ, Cowan C, Tayebjee MH, Graham LN, Pepper CB. Genetics of congenital and drug-induced long QT syndromes: current evidence and future research perspectives. J Interv Card Electrophysiol 2013; 37:9-19. [PMID: 23515882 DOI: 10.1007/s10840-013-9779-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 01/07/2013] [Indexed: 12/17/2022]
Abstract
The long QT syndrome (LQTS) is a condition characterized by abnormal prolongation of the QT interval with an associated risk of ventricular arrhythmias and sudden cardiac death. Congenital forms of LQTS arise due to rare and highly penetrant mutations that segregate in a Mendelian fashion. Over the years, multiple mutations in genes encoding ion channels and ion channel binding proteins have been reported to underlie congenital LQTS. Drugs are by far the most common cause of acquired forms of LQTS. Emerging evidence suggests that drug-induced LQTS also has a significant heritable component. However, the genetic substrate underlying drug-induced LQTS is presently largely unknown. In recent years, advances in next-generation sequencing technology and molecular biology techniques have significantly enhanced our ability to identify genetic variants underlying both monogenic diseases and more complex traits. In this review, we discuss the genetic basis of congenital and drug-induced LQTS and focus on future avenues of research in the field. Ultimately, a detailed characterization of the genetic substrate underlying congenital and drug-induced LQTS will enhance risk stratification and potentially result in the development of tailored genotype-based therapies.
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Affiliation(s)
- Saagar Mahida
- Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK.
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Anderson JH, Bos JM, Meyer FB, Cascino GD, Ackerman MJ. Concealed long QT syndrome and intractable partial epilepsy: a case report. Mayo Clin Proc 2012; 87:1128-31. [PMID: 23058853 PMCID: PMC3532686 DOI: 10.1016/j.mayocp.2012.07.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 06/14/2012] [Accepted: 07/06/2012] [Indexed: 12/23/2022]
Abstract
Herein, we describe a patient with concealed type 2 long QT syndrome with concomitant electroencephalogram-documented epilepsy. Although syncope in patients with long QT syndrome is common and often secondary to cerebral hypoxia after a protracted ventricular arrhythmia, this article demonstrates the importance of avoiding "tunnel vision" as patients with long QT syndrome could also have a primary seizure disorder. Identification of the etiology underlying seizurelike activity is paramount in instituting effective therapy. Furthermore, we theorize that abnormal KCHN2-encoded potassium channel repolarization in the brain could result in epilepsy and arrhythmias in long QT syndrome.
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Affiliation(s)
| | - Johan Martijn Bos
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN
| | | | | | - Michael J. Ackerman
- Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
- Correspondence: Address to Michael J. Ackerman, MD, PhD, Mayo Clinic Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Guggenheim Building 501, 200 First St SW, Rochester, MN 55905
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Stattin EL, Boström IM, Winbo A, Cederquist K, Jonasson J, Jonsson BA, Diamant UB, Jensen SM, Rydberg A, Norberg A. Founder mutations characterise the mutation panorama in 200 Swedish index cases referred for Long QT syndrome genetic testing. BMC Cardiovasc Disord 2012; 12:95. [PMID: 23098067 PMCID: PMC3520728 DOI: 10.1186/1471-2261-12-95] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 10/10/2012] [Indexed: 11/24/2022] Open
Abstract
Background Long QT syndrome (LQTS) is an inherited arrhythmic disorder characterised by prolongation of the QT interval on ECG, presence of syncope and sudden death. The symptoms in LQTS patients are highly variable, and genotype influences the clinical course. This study aims to report the spectrum of LQTS mutations in a Swedish cohort. Methods Between March 2006 and October 2009, two hundred, unrelated index cases were referred to the Department of Clinical Genetics, Umeå University Hospital, Sweden, for LQTS genetic testing. We scanned five of the LQTS-susceptibility genes (KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2) for mutations by DHPLC and/or sequencing. We applied MLPA to detect large deletions or duplications in the KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 genes. Furthermore, the gene RYR2 was screened in 36 selected LQTS genotype-negative patients to detect cases with the clinically overlapping disease catecholaminergic polymorphic ventricular tachycardia (CPVT). Results In total, a disease-causing mutation was identified in 103 of the 200 (52%) index cases. Of these, altered exon copy numbers in the KCNH2 gene accounted for 2% of the mutations, whereas a RYR2 mutation accounted for 3% of the mutations. The genotype-positive cases stemmed from 64 distinct mutations, of which 28% were novel to this cohort. The majority of the distinct mutations were found in a single case (80%), whereas 20% of the mutations were observed more than once. Two founder mutations, KCNQ1 p.Y111C and KCNQ1 p.R518*, accounted for 25% of the genotype-positive index cases. Genetic cascade screening of 481 relatives to the 103 index cases with an identified mutation revealed 41% mutation carriers who were at risk of cardiac events such as syncope or sudden unexpected death. Conclusion In this cohort of Swedish index cases with suspected LQTS, a disease-causing mutation was identified in 52% of the referred patients. Copy number variations explained 2% of the mutations and 3 of 36 selected cases (8%) harboured a mutation in the RYR2 gene. The mutation panorama is characterised by founder mutations (25%), even so, this cohort increases the amount of known LQTS-associated mutations, as approximately one-third (28%) of the detected mutations were unique.
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Affiliation(s)
- Eva-Lena Stattin
- Department of Medical Biosciences, Medical and Clinical Genetics, Umeå University, Umeå, Sweden.
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Lowe JS, Stroud DM, Yang T, Hall L, Atack TC, Roden DM. Increased late sodium current contributes to long QT-related arrhythmia susceptibility in female mice. Cardiovasc Res 2012; 95:300-7. [PMID: 22562703 DOI: 10.1093/cvr/cvs160] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIMS Female gender is a risk factor for long QT-related arrhythmias, but the underlying mechanisms remain uncertain. Here, we tested the hypothesis that gender-dependent function of the post-depolarization 'late' sodium current (I(Na-L)) contributes. METHODS AND RESULTS Studies were conducted in mice in which the canonical cardiac sodium channel Scn5a locus was disrupted, and expression of human wild-type SCN5A cDNA substituted. Baseline QT intervals were similar in male and female mice, but exposure to the sodium channel opener anemone toxin ATX-II elicited polymorphic ventricular tachycardia in 0/9 males vs. 6/9 females. Ventricular I(Na-L) and action potential durations were increased in myocytes isolated from female mice compared with those from males before and especially after treatment with ATX-II. Further, ATX-II elicited potentially arrhythmogenic early afterdepolarizations in myocytes from 0/5 male mice and 3/5 female mice. CONCLUSION These data identify variable late I(Na) as a modulator of gender-dependent arrhythmia susceptibility.
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Affiliation(s)
- John S Lowe
- Department of Medicine, Vanderbilt University School of Medicine, 2215B Garland Avenue, Nashville, TN 37232-0575, USA
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Van Dorn CS, Johnson JN, Taggart NW, Thorkelson L, Ackerman MJ. QTc values among children and adolescents presenting to the emergency department. Pediatrics 2011; 128:e1395-401. [PMID: 22123891 DOI: 10.1542/peds.2010-1513] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE Long-QT syndrome (LQTS) is both underdiagnosed and overdiagnosed. Many patients are incorrectly diagnosed as having LQTS after presenting to an emergency department (ED) with presyncope/syncope and demonstrating "borderline" QT-interval prolongation (QTc ≥ 440 milliseconds) in a sentinel ED-obtained electrocardiogram (ECG). We sought to evaluate the distribution and clinical significance of QT intervals in the ED. METHODS We retrospectively reviewed data for all patients 22 years of age or younger (N = 626; 369 females; age, mean ± SD: 17 ± 5 years) who had ECGs obtained in our ED between July 1, 2007, and June 30, 2008. A total of 223 patients were excluded because of known structural heart disease, arrhythmias, electrolyte abnormalities, or exposure to QT-interval-prolonging medications. RESULTS The average QTc was 428 ± 28 milliseconds (range: 344-566 milliseconds), and approximately one-third of patients had QTc values of ≥440 milliseconds (females: 41%; males: 21%). Overall, 104 patients presented with presyncope/syncope, of whom 14 (13%) had follow-up ECGs. On follow-up, these patients demonstrated significant decreases in QTc values of 33 ± 43 milliseconds (P < .04). Only 8 (31%) of 26 patients with presyncope/syncope with borderline QT values had follow-up ECGs performed, in 5 of which the QTc values were decreased significantly. No patients ultimately received LQTS diagnoses. CONCLUSIONS In the ED setting, approximately one-third of pediatric patients exhibited QTc values of ≥440 milliseconds and had significant normalization of QTc values in follow-up evaluations. First-time ECGs obtained after a syncopal episode must be interpreted with caution, particularly in the context of so-called borderline QT intervals.
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Cheng J, Norstrand DWV, Medeiros-Domingo A, Tester DJ, Valdivia CR, Tan BH, Vatta M, Makielski JC, Ackerman MJ. LQTS-associated mutation A257G in α1-syntrophin interacts with the intragenic variant P74L to modify its biophysical phenotype. CARDIOGENETICS 2011; 1. [PMID: 24319568 DOI: 10.4081/cardiogenetics.2011.e13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The SNTA1-encoded α1-syntrophin (SNTA1) missense mutation, p.A257G, causes long QT syndrome (LQTS) by pathogenic accentuation of Nav1.5's sodium current (INa). Subsequently, we found p.A257G in combination with the SNTA1 polymorphism, p.P74L in 4 victims of sudden infant death syndrome (SIDS) as well as in 3 adult controls. We hypothesized that p.P74L-SNTA1 could functionally modify the pathogenic phenotype of p.A257G-SNTA1, thus explaining its occurrence in non-LQTS populations. The SNTA1 variants p.P74L, p.A257G, and the combination variant p.P74L/p.A257G were engineered using PCR-based overlap-extension and were co-expressed heterologously with SCN5A in HEK293 cells. INa was recorded using the whole-cell method. Compared to wild-type (WT), the significant increase in peak INa and window current found with p.A257G was reversed by the intragenic variant p.P74L (p.P74L/p.A257G). These results report for the first time the intragenic rescue of an LQT-associated SNTA1 mutation when found in combination with the SNTA1 polymorphism p.P74L, suggesting an ever-increasing picture of complexity in terms of genetic risk stratification for arrhythmia.
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Affiliation(s)
- Jianding Cheng
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI, USA ; Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
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Recommendations for the Use of Genetic Testing in the Clinical Evaluation of Inherited Cardiac Arrhythmias Associated with Sudden Cardiac Death: Canadian Cardiovascular Society/Canadian Heart Rhythm Society Joint Position Paper. Can J Cardiol 2011; 27:232-45. [DOI: 10.1016/j.cjca.2010.12.078] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 12/23/2010] [Indexed: 11/23/2022] Open
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Abstract
Sudden infant death syndrome (SIDS) is a major contributor to postneonatal infant death, and is the third leading cause of infant mortality in the USA. While public health efforts have reduced these deaths in recent years, the pathogenesis of SIDS remains unclear. Epidemiological data on SIDS-related deaths have suggested genetic factors, and many studies have attempted to identify SIDS-associated genes. This has resulted in a large body of literature implicating various genes and their encoded proteins and signaling pathways in numerous cohorts of various sizes and ethnicities. This review has undertaken a systematic evaluation of these studies, identifying the pathways that have been implicated in these studies, including central nervous system pathways, cardiac channelopathies, immune dysfunction, metabolism/energy pathways, and nicotine response. This review also explores how new genomic techniques will aid in advancing our knowledge of the genomic risk factors associated with SIDS, including SNPs and copy number variation. Last, this review explores how the current information can be applied to aid in our assessment of the at risk infant population.
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Affiliation(s)
- David W Van Norstrand
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA.
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