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Zha F, Li X, Yin H, Huang D, Du Y, Zhou C. Case report: A 56-year-old woman presenting with torsades de pointes and cardiac arrest associated with levosimendan administration and underlying congenital long QT syndrome type 1. Heliyon 2024; 10:e29300. [PMID: 38644859 PMCID: PMC11033119 DOI: 10.1016/j.heliyon.2024.e29300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 03/30/2024] [Accepted: 04/04/2024] [Indexed: 04/23/2024] Open
Abstract
Torsades de Pointes (TdP) is a malignant polymorphic ventricular tachycardia with heart rate corrected QT interval (QTc) prolongation, which may be attributed to congenital and acquired factors. Although various acquired factors for TdP have been summarized, levosimendan administration in complex postoperative settings is relatively uncommon. Timely identification of potential causes and appropriate management may improve the outcome. Herein, we describe the postoperative case of a 56-year-old female with initial normal QTc who accepted the administration of levosimendan for heart failure, suffered TdP, cardiac arrest, and possible Takotsubo cardiomyopathy, further genetically confirmed as long QT syndrome type 1 (LQT1). The patient was successfully treated with magnesium sulfate, atenolol, and implantable cardioverter defibrillator implantation. There should be a careful evaluation of the at-risk populations and close monitoring of the electrocardiograms, particularly the QT interval, to reduce the risk of near-fatal arrhythmias during the use of levosimendan.
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Affiliation(s)
- Fengyan Zha
- Department of Surgical Intensive Care Unit, Fuwai Hospital Chinese Academy of Medical Sciences, Shenzhen, SZ, China
| | - Xing Li
- Department of Surgical Intensive Care Unit, Fuwai Hospital Chinese Academy of Medical Sciences, Shenzhen, SZ, China
| | - Hui Yin
- Department of Surgical Intensive Care Unit, Fuwai Hospital Chinese Academy of Medical Sciences, Shenzhen, SZ, China
| | - Di Huang
- Department of Surgical Intensive Care Unit, Fuwai Hospital Chinese Academy of Medical Sciences, Shenzhen, SZ, China
| | - Yu Du
- Department of Surgical Intensive Care Unit, Fuwai Hospital Chinese Academy of Medical Sciences, Beijing, BJ, China
| | - Chuzhi Zhou
- Department of Surgical Intensive Care Unit, Fuwai Hospital Chinese Academy of Medical Sciences, Shenzhen, SZ, China
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2
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Drost L, Finke JB, Bachmann P, Schächinger H. Cold pressor stress effects on cardiac repolarization. Stress 2024; 27:2352626. [PMID: 38766757 DOI: 10.1080/10253890.2024.2352626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 04/29/2024] [Indexed: 05/22/2024] Open
Abstract
The cold pressor test (CPT) elicits strong cardiovascular reactions via activation of the sympathetic nervous system (SNS), yielding subsequent increases in heart rate (HR) and blood pressure (BP). However, little is known on how exposure to the CPT affects cardiac ventricular repolarization. Twenty-eight healthy males underwent both a bilateral feet CPT and a warm water (WW) control condition on two separate days, one week apart. During pre-stress baseline and stress induction cardiovascular signals (ECG lead II, Finometer BP) were monitored continuously. Salivary cortisol and subjective stress ratings were assessed intermittently. Corrected QT (QTc) interval length and T-wave amplitude (TWA) were assessed for each heartbeat and subsequently aggregated individually over baseline and stress phases, respectively. CPT increases QTc interval length and elevates the TWA. Stress-induced changes in cardiac repolarization are only in part and weakly correlated with cardiovascular and cortisol stress-reactivity. Besides its already well-established effects on cardiovascular, endocrine, and subjective responses, CPT also impacts on cardiac repolarization by elongation of QTc interval length and elevation of TWA. CPT effects on cardiac repolarization share little variance with the other indices of stress reactivity, suggesting a potentially incremental value of this parameter for understanding psychobiological adaptation to acute CPT stress.
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Affiliation(s)
- Lisa Drost
- Department of Clinical Psychophysiology, University of Trier, Trier, Germany
| | - Johannes B Finke
- Department of Clinical Psychology and Psychotherapy, University of Siegen, Siegen, Germany
| | - Petra Bachmann
- Department of Clinical Psychophysiology, University of Trier, Trier, Germany
| | - Hartmut Schächinger
- Department of Clinical Psychophysiology, University of Trier, Trier, Germany
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3
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Suna G, Mellor GJ. Explaining the Unexplained: A Practical Approach to Investigating the Cardiac Arrest Survivor. Arrhythm Electrophysiol Rev 2023; 12:e27. [PMID: 38124802 PMCID: PMC10731537 DOI: 10.15420/aer.2023.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Accepted: 10/12/2023] [Indexed: 12/23/2023] Open
Abstract
Sudden cardiac arrest (SCA) is a common cause of death. The majority of SCA is caused by ventricular arrhythmia due to underlying CHD. Aborted SCA with no apparent diagnosis after initial assessment with ECG, echocardiography and coronary assessment is referred to as unexplained cardiac arrest (UCA). Systematic evaluation of such patients may reveal a specific diagnosis in up to half of patients before a diagnosis of idiopathic VF is assigned. Specific diagnoses include inherited cardiac conditions, such as latent cardiomyopathies or inherited primary electrical disease. Identifying the cause of UCA is therefore not only critical for appropriate management of the SCA survivors to prevent recurrence, but also for their family members who may be at risk of the same condition. This review provides a tiered, systematic approach for the investigation of UCA.
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Affiliation(s)
- Gonca Suna
- Cardiology Department, Royal Papworth Hospital NHS Foundation Trust Cambridge, UK
| | - Greg J Mellor
- Cardiology Department, Royal Papworth Hospital NHS Foundation Trust Cambridge, UK
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4
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van Weperen VYH, Ripplinger CM, Vaseghi M. Autonomic control of ventricular function in health and disease: current state of the art. Clin Auton Res 2023; 33:491-517. [PMID: 37166736 PMCID: PMC10173946 DOI: 10.1007/s10286-023-00948-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 04/20/2023] [Indexed: 05/12/2023]
Abstract
PURPOSE Cardiac autonomic dysfunction is one of the main pillars of cardiovascular pathophysiology. The purpose of this review is to provide an overview of the current state of the art on the pathological remodeling that occurs within the autonomic nervous system with cardiac injury and available neuromodulatory therapies for autonomic dysfunction in heart failure. METHODS Data from peer-reviewed publications on autonomic function in health and after cardiac injury are reviewed. The role of and evidence behind various neuromodulatory therapies both in preclinical investigation and in-use in clinical practice are summarized. RESULTS A harmonic interplay between the heart and the autonomic nervous system exists at multiple levels of the neuraxis. This interplay becomes disrupted in the setting of cardiovascular disease, resulting in pathological changes at multiple levels, from subcellular cardiac signaling of neurotransmitters to extra-cardiac, extra-thoracic remodeling. The subsequent detrimental cycle of sympathovagal imbalance, characterized by sympathoexcitation and parasympathetic withdrawal, predisposes to ventricular arrhythmias, progression of heart failure, and cardiac mortality. Knowledge on the etiology and pathophysiology of this condition has increased exponentially over the past few decades, resulting in a number of different neuromodulatory approaches. However, significant knowledge gaps in both sympathetic and parasympathetic interactions and causal factors that mediate progressive sympathoexcitation and parasympathetic dysfunction remain. CONCLUSIONS Although our understanding of autonomic imbalance in cardiovascular diseases has significantly increased, specific, pivotal mediators of this imbalance and the recognition and implementation of available autonomic parameters and neuromodulatory therapies are still lagging.
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Affiliation(s)
- Valerie Y H van Weperen
- Division of Cardiology, Department of Medicine, UCLA Cardiac Arrythmia Center, University of California, 100 Medical Plaza, Suite 660, Los Angeles, CA, 90095, USA
| | | | - Marmar Vaseghi
- Division of Cardiology, Department of Medicine, UCLA Cardiac Arrythmia Center, University of California, 100 Medical Plaza, Suite 660, Los Angeles, CA, 90095, USA.
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5
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Winbo A, Ramanan S, Eugster E, Rydberg A, Jovinge S, Skinner JR, Montgomery JM. Functional hyperactivity in long QT syndrome type 1 pluripotent stem cell-derived sympathetic neurons. Am J Physiol Heart Circ Physiol 2021; 321:H217-H227. [PMID: 34142889 DOI: 10.1152/ajpheart.01002.2020] [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] [Indexed: 11/22/2022]
Abstract
Sympathetic activation is an established trigger of life-threatening cardiac events in long QT syndrome type 1 (LQT1). KCNQ1 loss-of-function variants, which underlie LQT1, have been associated with both cardiac arrhythmia and neuronal hyperactivity pathologies. However, the LQT1 sympathetic neuronal phenotype is unknown. Here, we aimed to study human induced pluripotent stem cell (hiPSC)-derived sympathetic neurons (SNs) to evaluate neuronal functional phenotype in LQT1. We generated hiPSC-SNs from two patients with LQT1 with a history of sympathetically triggered arrhythmia and KCNQ1 loss-of-function genotypes (c.781_782delinsTC and p.S349W/p.R518X). Characterization of hiPSC-SNs was performed using immunohistochemistry, enzyme-linked immunosorbent assay, and whole cell patch clamp electrophysiology, and functional LQT1 hiPSC-SN phenotypes compared with healthy control (WT) hiPSC-SNs. hiPSC-SNs stained positive for tyrosine hydroxylase, peripherin, KCNQ1, and secreted norepinephrine. hiPSC-SNs at 60 ± 2.2 days in vitro had healthy resting membrane potentials (-60 ± 1.3 mV), and fired rapid action potentials with mature kinetics in response to stimulation. Significant hyperactivity in LQT1 hiPSC-SNs was evident via increased norepinephrine release, increased spontaneous action potential frequency, increased total inward current density, and reduced afterhyperpolarization, compared with age-matched WT hiPSC-SNs. A significantly higher action potential frequency upon current injection and larger synaptic current amplitudes in compound heterozygous p.S349W/p.R518X hiPSC-SNs compared with heterozygous c.781_782delinsTC hiPSC-SNs was also observed, suggesting a potential genotype-phenotype correlation. Together, our data reveal increased neurotransmission and excitability in heterozygous and compound heterozygous patient-derived LQT1 sympathetic neurons, suggesting that the cellular arrhythmogenic potential in LQT1 is not restricted to cardiomyocytes.NEW & NOTEWORTHY Here, we present the first study of patient-derived LQT1 sympathetic neurons that are norepinephrine secreting, and electrophysiologically functional, in vitro. Our data reveal a novel LQT1 sympathetic neuronal phenotype of increased neurotransmission and excitability. The identified sympathetic neuronal hyperactivity phenotype is of particular relevance as it could contribute to the mechanisms underlying sympathetically triggered arrhythmia in LQT1.
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Affiliation(s)
- Annika Winbo
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Manaaki Mānawa Centre for Heart Research, University of Auckland, Auckland, New Zealand.,Department of Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland, New Zealand.,The Cardiac Inherited Disease Group (CIDG), Auckland, New Zealand.,Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden
| | - Suganeya Ramanan
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Manaaki Mānawa Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Emily Eugster
- DeVos Cardiovascular Research Program Spectrum Health/Van Andel Research Institute, Grand Rapids, Michigan
| | - Annika Rydberg
- Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden
| | - Stefan Jovinge
- DeVos Cardiovascular Research Program Spectrum Health/Van Andel Research Institute, Grand Rapids, Michigan.,Cardiovascular Institute, Stanford University of Medicine, Stanford, California
| | - Jonathan R Skinner
- Manaaki Mānawa Centre for Heart Research, University of Auckland, Auckland, New Zealand.,Department of Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland, New Zealand.,The Cardiac Inherited Disease Group (CIDG), Auckland, New Zealand
| | - Johanna M Montgomery
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Manaaki Mānawa Centre for Heart Research, University of Auckland, Auckland, New Zealand
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6
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Stiles MK, Wilde AAM, Abrams DJ, Ackerman MJ, Albert CM, Behr ER, Chugh SS, Cornel MC, Gardner K, Ingles J, James CA, Juang JMJ, Kääb S, Kaufman ES, Krahn AD, Lubitz SA, MacLeod H, Morillo CA, Nademanee K, Probst V, Saarel EV, Sacilotto L, Semsarian C, Sheppard MN, Shimizu W, Skinner JR, Tfelt-Hansen J, Wang DW. 2020 APHRS/HRS expert consensus statement on the investigation of decedents with sudden unexplained death and patients with sudden cardiac arrest, and of their families. J Arrhythm 2021; 37:481-534. [PMID: 34141003 PMCID: PMC8207384 DOI: 10.1002/joa3.12449] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 10/14/2020] [Indexed: 12/26/2022] Open
Abstract
This international multidisciplinary document intends to provide clinicians with evidence-based practical patient-centered recommendations for evaluating patients and decedents with (aborted) sudden cardiac arrest and their families. The document includes a framework for the investigation of the family allowing steps to be taken, should an inherited condition be found, to minimize further events in affected relatives. Integral to the process is counseling of the patients and families, not only because of the emotionally charged subject, but because finding (or not finding) the cause of the arrest may influence management of family members. The formation of multidisciplinary teams is essential to provide a complete service to the patients and their families, and the varied expertise of the writing committee was formulated to reflect this need. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by Class of Recommendation and Level of Evidence. The recommendations were opened for public comment and reviewed by the relevant scientific and clinical document committees of the Asia Pacific Heart Rhythm Society (APHRS) and the Heart Rhythm Society (HRS); the document underwent external review and endorsement by the partner and collaborating societies. While the recommendations are for optimal care, it is recognized that not all resources will be available to all clinicians. Nevertheless, this document articulates the evaluation that the clinician should aspire to provide for patients with sudden cardiac arrest, decedents with sudden unexplained death, and their families.
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Affiliation(s)
- Martin K Stiles
- Waikato Clinical School Faculty of Medicine and Health Science The University of Auckland Hamilton New Zealand
| | - Arthur A M Wilde
- Heart Center Department of Clinical and Experimental Cardiology Amsterdam University Medical Center University of Amsterdam Amsterdam the Netherlands
| | | | | | | | - Elijah R Behr
- Cardiovascular Clinical Academic Group, Molecular and Clinical Sciences Institute St George's University of London, and St George's University Hospitals NHS Foundation Trust London UK
| | | | - Martina C Cornel
- Amsterdam University Medical Center Vrije Universiteit Amsterdam Clinical Genetics Amsterdam Public Health Research Institute Amsterdam the Netherlands
| | | | - Jodie Ingles
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute The University of Sydney Sydney Australia
| | | | - Jyh-Ming Jimmy Juang
- Cardiovascular Center and Division of Cardiology Department of Internal Medicine National Taiwan University Hospital and National Taiwan University College of Medicine Taipei Taiwan
| | - Stefan Kääb
- Department of Medicine I University Hospital LMU Munich Munich Germany
| | | | | | | | - Heather MacLeod
- Data Coordinating Center for the Sudden Death in the Young Case Registry Okemos MI USA
| | | | - Koonlawee Nademanee
- Chulalongkorn University Faculty of Medicine, and Pacific Rim Electrophysiology Research Institute at Bumrungrad Hospital Bangkok Thailand
| | | | - Elizabeth V Saarel
- Cleveland Clinic Lerner College of Cardiology at Case Western Reserve University Cleveland OH USA
- St Luke's Medical Center Boise ID USA
| | - Luciana Sacilotto
- Heart Institute University of São Paulo Medical School São Paulo Brazil
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute The University of Sydney Sydney Australia
| | - Mary N Sheppard
- Cardiovascular Clinical Academic Group, Molecular and Clinical Sciences Institute St George's University of London, and St George's University Hospitals NHS Foundation Trust London UK
| | - Wataru Shimizu
- Department of Cardiovascular Medicine Nippon Medical School Tokyo Japan
| | | | - Jacob Tfelt-Hansen
- Department of Forensic Medicine Faculty of Medical Sciences Rigshospitalet Copenhagen Denmark
| | - Dao Wu Wang
- The First Affiliated Hospital of Nanjing Medical University Nanjing China
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7
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Stiles MK, Wilde AAM, Abrams DJ, Ackerman MJ, Albert CM, Behr ER, Chugh SS, Cornel MC, Gardner K, Ingles J, James CA, Jimmy Juang JM, Kääb S, Kaufman ES, Krahn AD, Lubitz SA, MacLeod H, Morillo CA, Nademanee K, Probst V, Saarel EV, Sacilotto L, Semsarian C, Sheppard MN, Shimizu W, Skinner JR, Tfelt-Hansen J, Wang DW. 2020 APHRS/HRS expert consensus statement on the investigation of decedents with sudden unexplained death and patients with sudden cardiac arrest, and of their families. Heart Rhythm 2021; 18:e1-e50. [PMID: 33091602 PMCID: PMC8194370 DOI: 10.1016/j.hrthm.2020.10.010] [Citation(s) in RCA: 147] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 10/09/2020] [Indexed: 12/13/2022]
Abstract
This international multidisciplinary document intends to provide clinicians with evidence-based practical patient-centered recommendations for evaluating patients and decedents with (aborted) sudden cardiac arrest and their families. The document includes a framework for the investigation of the family allowing steps to be taken, should an inherited condition be found, to minimize further events in affected relatives. Integral to the process is counseling of the patients and families, not only because of the emotionally charged subject, but because finding (or not finding) the cause of the arrest may influence management of family members. The formation of multidisciplinary teams is essential to provide a complete service to the patients and their families, and the varied expertise of the writing committee was formulated to reflect this need. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by Class of Recommendation and Level of Evidence. The recommendations were opened for public comment and reviewed by the relevant scientific and clinical document committees of the Asia Pacific Heart Rhythm Society (APHRS) and the Heart Rhythm Society (HRS); the document underwent external review and endorsement by the partner and collaborating societies. While the recommendations are for optimal care, it is recognized that not all resources will be available to all clinicians. Nevertheless, this document articulates the evaluation that the clinician should aspire to provide for patients with sudden cardiac arrest, decedents with sudden unexplained death, and their families.
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Affiliation(s)
- Martin K Stiles
- Waikato Clinical School, Faculty of Medicine and Health Science, The University of Auckland, Hamilton, New Zealand
| | - Arthur A M Wilde
- Amsterdam University Medical Center, University of Amsterdam, Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam, the Netherlands
| | | | | | | | - Elijah R Behr
- Cardiovascular Clinical Academic Group, Molecular and Clinical Sciences Institute, St George's, University of London, and St George's University Hospitals NHS Foundation Trust, London, United Kingdom
| | - Sumeet S Chugh
- Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Martina C Cornel
- Amsterdam University Medical Center, Vrije Universiteit Amsterdam, Clinical Genetics, Amsterdam Public Health Research Institute, Amsterdam, the Netherlands
| | | | - Jodie Ingles
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Sydney, Australia
| | | | - Jyh-Ming Jimmy Juang
- Cardiovascular Center and Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Stefan Kääb
- Department of Medicine I, University Hospital, LMU Munich, Munich, Germany
| | | | - Andrew D Krahn
- The University of British Columbia, Vancouver, British Columbia, Canada
| | | | - Heather MacLeod
- Data Coordinating Center for the Sudden Death in the Young Case Registry, Okemos, Michigan, USA
| | | | - Koonlawee Nademanee
- Chulalongkorn University, Faculty of Medicine, and Pacific Rim Electrophysiology Research Institute at Bumrungrad Hospital, Bangkok, Thailand
| | | | - Elizabeth V Saarel
- Cleveland Clinic Lerner College of Cardiology at Case Western Reserve University, Cleveland, Ohio, and St Luke's Medical Center, Boise, Idaho, USA
| | - Luciana Sacilotto
- Heart Institute, University of São Paulo Medical School, São Paulo, Brazil
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Sydney, Australia
| | - Mary N Sheppard
- Cardiovascular Clinical Academic Group, Molecular and Clinical Sciences Institute, St George's, University of London, and St George's University Hospitals NHS Foundation Trust, London, United Kingdom
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
| | - Jonathan R Skinner
- Cardiac Inherited Disease Group, Starship Hospital, Auckland, New Zealand
| | - Jacob Tfelt-Hansen
- Department of Forensic Medicine, Faculty of Medical Sciences, Rigshospitalet, Copenhagen, Denmark
| | - Dao Wu Wang
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
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8
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Grant AJ, Kanwal A, Shah AB. Swimming: What the Sports Cardiologist Should Know. CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2020. [DOI: 10.1007/s11936-020-00876-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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9
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Takahashi K, Shimizu W, Makita N, Nakayashiro M. Dynamic QT response to cold-water face immersion in long-QT syndrome type 3. Pediatr Int 2020; 62:899-906. [PMID: 32449227 PMCID: PMC7496693 DOI: 10.1111/ped.14319] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 05/03/2020] [Accepted: 05/18/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Abnormal dynamics of QT intervals in response to sympathetic nervous system stimulation are used to diagnose long-QT syndrome (LQTS). We hypothesized that parasympathetic stimulation with cold-water face immersion following exercise would influence QT dynamics in patients with LQTS type 3 (LQT3). METHODS Study participants (n = 42; mean age = 11.2 years) comprised 20 genotyped LQTS children and 22 healthy children. The LQTS group was divided into LQT3 (n = 12) and non-LQT3 (n = 8) subgroups. Provocative testing for assessing QT dynamics comprised a treadmill exercise followed by cold-water face immersion. The QT intervals were automatically measured at rest and during exercise, recovery, and cold-water face immersion. The QT/heart rate (HR) relationship was visualized by plotting beat-to-beat confluence of the data. RESULTS The QT/HR slopes, determined by linear regression analysis, were steeper in the LQTS group than in the control group during exercise and immersion tests: -2.16 ± 0.63 versus -1.21 ± 0.28, P < 0.0001, and -2.02 ± 0.76 vs -0.75 ± 0.24, P < 0.0001, respectively. The LQT3 patients had steeper slopes in the immersion test than did non-LQT3 and control individuals: -2.42 ± 0.52 vs -1.40 ± 0.65, P < 0.0001, and vs -0.75 ± 0.24, P < 0.0001. CONCLUSIONS The QT dynamics of LQT3 patients differ from those of other LQTS subtypes during the post-exercise cold-water face immersion test in this study. Abnormal QT dynamics during the parasympathetic provocative test are concordant with the fact that cardiac events occur when HRs are lower or during sleep in LQT3 patients.
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Affiliation(s)
- Kazuhiro Takahashi
- Department of Pediatric CardiologyOkinawa Nanbu and Children’s Medical CenterOkinawaJapan
| | | | - Naomasa Makita
- National Cerebral and Cardiovascular CenterResearch InstituteOsakaJapan
| | - Mami Nakayashiro
- Department of Pediatric CardiologyOkinawa Nanbu and Children’s Medical CenterOkinawaJapan
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10
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Sudhakaran S, Yazdani L, Wheelan KR, Rao PK. The ketogenic diet and the QT interval. Proc (Bayl Univ Med Cent) 2019; 33:77-79. [PMID: 32063779 DOI: 10.1080/08998280.2019.1664220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/26/2019] [Accepted: 08/29/2019] [Indexed: 12/12/2022] Open
Abstract
Long QT syndrome is a disorder of ventricular myocardial repolarization associated with an increased risk of life-threatening cardiac arrhythmias and sudden cardiac death. This report highlights a case of QT prolongation with torsades de pointes in a patient with baseline congenital long QT syndrome, believed to be precipitated by metabolic changes associated with the "ketogenic diet."
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Affiliation(s)
- Sivakumar Sudhakaran
- Department of Internal Medicine, Baylor University Medical Center and Baylor Jack and Jane Hamilton Heart and Vascular HospitalDallasTexas
| | - Laila Yazdani
- Department of Internal Medicine, Baylor University Medical Center and Baylor Jack and Jane Hamilton Heart and Vascular HospitalDallasTexas
| | - Kevin R Wheelan
- Department of Internal Medicine, Baylor University Medical Center and Baylor Jack and Jane Hamilton Heart and Vascular HospitalDallasTexas
| | - Praveen K Rao
- Department of Internal Medicine, Baylor University Medical Center and Baylor Jack and Jane Hamilton Heart and Vascular HospitalDallasTexas
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11
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Kwok SY, Pflaumer A, Pantaleo SJ, Date E, Jadhav M, Davis AM. Ten-year experience in atenolol use and exercise evaluation in children with genetically proven long QT syndrome. J Arrhythm 2017; 33:624-629. [PMID: 29255512 PMCID: PMC5728996 DOI: 10.1016/j.joa.2017.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 07/19/2017] [Accepted: 08/15/2017] [Indexed: 11/13/2022] Open
Abstract
Background Due to its availability, atenolol is the primary beta-blocker used in Australia for children with long QT syndrome. There is limited data on long-term follow-up of its use. Methods A single-tertiary-center, retrospective, observational study investigating all children and adolescents who had genetically proven long QT syndrome type 1 (LQT1) and type 2 (LQT2) was conducted. Their pretreatment exercise tests were evaluated for QTc intervals into the recovery phase of exercise. Results Eighty six patients were identified (LQT1, 67, and LQT2, 19) from 2004 to 2014. The majority (86%) of patients were initially referred for family screening. Atenolol was administered at a mean dose of 1.58 ± 0.51 mg/kg/day. During the median follow-up period of 4.29 years, only one proband developed ventricular arrhythmia whilst taking atenolol, No patient had cardiac arrest or aborted cardiac arrest. With respect to side effects of atenolol, only two patients had intolerable side effects necessitating changes of medication. Evaluation of exercise tests (pretreatment) demonstrated that corrected QT (QTc) intervals at 2–3 min into the recovery phase of exercise were significantly prolonged for LQT1 patients. LQT1 patients with transmembrane mutation had longer QTc intervals than their C-terminus mutation counterparts, reaching statistical significance at 3 min into the recovery phase of exercise. Conclusions Atenolol is an effective treatment for genetically proven LQT1 and LQT2 children and adolescents, with good tolerability. In LQT1 patients, QTc intervals at 2–3 min into the recovery phase of exercise were significantly prolonged, particularly in patients with transmembrane mutations.
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Key Words
- Atenolol
- Beta-blocker
- ECG, Electrocardiogram
- Exercise
- ICD, Implantable cardioverter-defibrillator
- LCSD, Left cardiac sympathetic denervation
- LQT1, Long QT syndrome type 1
- LQT2, Long QT syndrome type 2
- LQTS, Long QT syndrome
- Long QT syndrome
- Pediatrics
- QTc, Corrected QT
- SD, Standard deviation
- SFM, Screened family members
- TdP, Torsade de pointes
- min, Minutes
- s, Seconds
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Affiliation(s)
- Sit-Yee Kwok
- Department of Cardiology, Royal Children's Hospital, Melbourne, Australia
| | - Andreas Pflaumer
- Department of Cardiology, Royal Children's Hospital, Melbourne, Australia.,Murdoch Children's Research Institute, Parkville, VIC 3052, Australia.,Department of Paediatrics, Melbourne University, Australia
| | | | - Erin Date
- Department of Cardiology, Royal Children's Hospital, Melbourne, Australia
| | - Mangesh Jadhav
- Department of Cardiology, Royal Children's Hospital, Melbourne, Australia
| | - Andrew Mark Davis
- Department of Cardiology, Royal Children's Hospital, Melbourne, Australia.,Murdoch Children's Research Institute, Parkville, VIC 3052, Australia.,Department of Paediatrics, Melbourne University, Australia
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Narayanan K, Chugh SS. The 12-lead electrocardiogram and risk of sudden death: current utility and future prospects. Europace 2016; 17 Suppl 2:ii7-13. [PMID: 26842119 DOI: 10.1093/europace/euv121] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
More than 100 years after it was first invented, the 12-lead electrocardiogram (ECG) continues to occupy an important place in the diagnostic armamentarium of the practicing clinician. With the recognition of relatively rare but important clinical entities such as Wolff-Parkinson-White and the long QT syndrome, this clinical tool was firmly established as a test for assessing risk of sudden cardiac death (SCD). However, over the past two decades the role of the ECG in risk prediction for common forms of SCD, for example in patients with coronary artery disease, has been the focus of considerable investigation. Especially in light of the limitations of current risk stratification approaches, there is a renewed focus on this broadly available and relatively inexpensive test. Various abnormalities of depolarization and repolarization on the ECG have been linked to SCD risk; however, more focused work is needed before they can be deployed in the clinical arena. The present review summarizes the current knowledge on various ECG risk markers for prediction of SCD and discusses some future directions in this field.
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Affiliation(s)
- Kumar Narayanan
- The Heart Institute, Advanced Health Sciences Pavilion Suite A3100, Cedars-Sinai Medical Center, 127 S. San Vicente Blvd, Los Angeles, CA 90048, USA
| | - Sumeet S Chugh
- The Heart Institute, Advanced Health Sciences Pavilion Suite A3100, Cedars-Sinai Medical Center, 127 S. San Vicente Blvd, Los Angeles, CA 90048, USA
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13
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Takahashi K, Nabeshima T, Nakayashiro M, Ganaha H. QT Dynamics During Exercise in Asymptomatic Children with Long QT Syndrome Type 3. Pediatr Cardiol 2016; 37:860-7. [PMID: 26921063 DOI: 10.1007/s00246-016-1360-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/13/2016] [Indexed: 01/08/2023]
Abstract
Sympathetic provocative testing is commonly used to detect the abnormal QT dynamics in long QT syndrome (LQTS) patients, particularly LQTS type 1 and type 2. However, little is known about LQTS type 3 (LQT3). We investigated QT dynamics during exercise testing in LQTS patients, particularly LQT3. This study included 37 subjects, comprising 16 genotyped LQTS patients and 21 unrelated healthy subjects without QT prolongation. LQTS patients were divided into LQT3 and non-LQT3 groups. During exercise tests using a modified Bruce protocol, 12-lead electrocardiogram monitoring was performed using a novel multifunctional electrocardiograph. QT intervals were automatically measured. The QT/heart rate (HR) relationship was visualized by plotting the beat-to-beat confluence of the recorded data. A linear regression analysis was performed to determine the QT/HR slope and intercept. Estimated QT intervals at HR 60 bpm (QT60) were calculated by the regression line formula. QT/HR slopes were steeper for each LQTS group than for the control group (P < 0.001). QT60 values demonstrated a moderate correlation with QT intervals at rest (P < 0.0001) for both groups. The corrected QT intervals (QTc) at 4 min of recovery after exercise were significantly longer in the non-LQT3 group than in the control group but were not different between the LQT3 and the control groups. Abnormal QT dynamics during exercise testing were observed in both LQT3 patients and other LQTS subtypes. This method may be useful for directing genetic testing in subjects with borderline prolonged QT intervals.
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Affiliation(s)
- Kazuhiro Takahashi
- Department of Pediatric Cardiology, Okinawa Children's Medical Center, 118-1 Arakawa, Haebaru-chou, Okinawa, 901-1193, Japan.
| | - Taisuke Nabeshima
- Department of Pediatric Cardiology, Okinawa Children's Medical Center, 118-1 Arakawa, Haebaru-chou, Okinawa, 901-1193, Japan
| | - Mami Nakayashiro
- Department of Pediatric Cardiology, Okinawa Children's Medical Center, 118-1 Arakawa, Haebaru-chou, Okinawa, 901-1193, Japan
| | - Hitoshi Ganaha
- Department of Pediatric Cardiology, Okinawa Children's Medical Center, 118-1 Arakawa, Haebaru-chou, Okinawa, 901-1193, Japan
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[Perioperative treatment of patients with long QT syndrome]. Anaesthesist 2015; 64:625-37; quiz 638-9. [PMID: 26260197 DOI: 10.1007/s00101-015-0067-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Long QT syndrome (LQTS) is caused by a change in cardiac repolarization due to functional ion channel dysfunction which is associated with an elongation of the QT interval (hence the name) in the electrocardiogram and a predisposition to cardiac rhythm disorders (e.g. torsade de pointes, TdP) as well as cardiac events up to sudden cardiac death. There is a congenital (cLQTS) and an acquired (aLQTS) form of the disease. The prevalence of cLQTS is 1 in 2000 but aLQTS is much more common and includes a grey area due to many asymptomatic patients. The LQTS is, therefore, more common than malignant hyperthermia which is much discussed in anesthesiology and has a reported prevalence in the population of 1:3000. Considering the prevalence of both aLQTS as well as cLQTS the importance of the LQTS seems to be underestimated in current perioperative care. Potential perioperative risks of such patients can be significantly reduced by appropriate patient management. This includes adequate preoperative preparation, the correct choice of anesthetic medication as well as adequate perioperative monitoring and preparedness for immediate pharmaceutical and electrical intervention in case of typical cardiac rhythm disturbances, such as TdP arrhythmia.
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Mellor G, Behr ER. Sudden Unexplained Death - Treating the Family. Arrhythm Electrophysiol Rev 2014; 3:156-60. [PMID: 26835084 DOI: 10.15420/aer.2014.3.3.156] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 11/03/2014] [Indexed: 01/08/2023] Open
Abstract
Sudden unexplained death in the context of a normal heart at post-mortem and negative toxicological analysis is termed sudden arrhythmic death syndrome (SADS). SADS is often due to cardiac genetic disease, particularly channelopathies. Assessment of family members of SADS victims will reveal at least one affected individual in up to half of families. Specialist evaluation begins with an expert cardiac autopsy that improves diagnostic accuracy and minimises erroneous interpretation of minor pathological findings. Retention of appropriate material for post-mortem genetic testing, 'the molecular autopsy', is recommended as this may provide a genetic diagnosis in up to a third of cases. Clinical assessment of families initially comprises 12-lead ECG with high right ventricular leads, echocardiogram and exercise testing. Additional investigations include sodium channel blocker and epinephrine provocation tests. Families with a diagnosis should be managed as per guidelines. Those with negative investigations can generally be discharged unless they are young and/or symptomatic.
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Affiliation(s)
- Greg Mellor
- Clinical Research Fellow & Specialist Registrar Cardiology
| | - Elijah R Behr
- Reader in Cardiovascular Medicine & Honorary Consultant Cardiologist & Electrophysiologist Cardiac Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London
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16
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Patel D, Singh P, Katz W, Hughes C, Chopra K, Němec J. QT interval prolongation in end-stage liver disease cannot be explained by nonhepatic factors. Ann Noninvasive Electrocardiol 2014; 19:574-81. [PMID: 24762117 DOI: 10.1111/anec.12161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
INTRODUCTION QT interval prolongation in patients with end-stage liver disease (ESLD) is common. However, electrolyte abnormalities, renal insufficiency, treatment with QT-prolonging drugs, and other factors known to prolong QT interval independently of liver disease occur frequently in ESLD. Moreover, elevated heart rate may be present in ESLD and result in spurious QTc prolongation if the Bazett formula is used for rate correction. It thus remains unclear whether QT prolongation in ESLD is directly caused by liver failure, or indirectly by these confounding factors. METHODS Medical records of all patients (n = 437) who received orthotopic liver transplantation (OLTx) at our institution between 2008 and 2011 were reviewed. Data from 51 patients with available pre-OLTx dobutamine stress echo (DSE), post-OLTx ECG and without nonhepatic factors affecting QT interval duration were analyzed. For each patient, QT versus RR regression line was calculated from ECG tracings obtained during DSE. The QT interval on post-OLTx ECG was compared with the pre-OLTx QT predicted by the regression line for the same RR interval. RESULTS QT interval shortened significantly post-OLTx (from 394 ± 47 to 364 ± 45 ms at RR interval 750 ± 144 ms; P < 0.002) when compared using the regression method. Corrected QT intervals calculated by Bazett and Fridericia formulas also shortened. Patients with prolonged QT pre-OLTx had significantly higher INR and lower serum albumin. CONCLUSION ESLD impairs ventricular repolarization even in the absence of other known factors affecting repolarization. QT prolongation in ESLD is associated with impaired synthetic liver function.
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Affiliation(s)
- Divyang Patel
- University of Pittsburgh School of Medicine, Pittsburgh, PA
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Abstract
Congenital long QT syndrome (LQTS) is a genetically heterogeneous group of heritable disorders of myocardial repolarization linked by the shared clinical phenotype of QT prolongation on electrocardiogram and an increased risk of potentially life-threatening cardiac arrhythmias. At the molecular level, mutations in 15 distinct LQTS-susceptibility genes that encode ion channel pore-forming α-subunits and accessory β-subunits central to the electromechanical function of the heart have been implicated in its pathogenesis. Over the past 2 decades, our evolving understanding of the electrophysiological mechanisms by which specific genetic substrates perturb the cardiac action potential has translated into vastly improved approaches to the diagnosis, risk stratification, and treatment of patients with LQTS. In this review, we describe how our understanding of the molecular underpinnings of LQTS has yielded numerous clinically meaningful genotype-phenotype correlations and how these insights have translated into genotype- and phenotype-guided approaches to the clinical management of LQTS.
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Affiliation(s)
| | - Michael J. Ackerman
- Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
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Epinephrine: the drug of choice for anaphylaxis-a statement of the world allergy organization. World Allergy Organ J 2013. [PMID: 23282530 PMCID: PMC3666145 DOI: 10.1097/1939-4551-1-s2-s18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Anaphylaxis is an acute and potentially lethal multisystem allergic reaction.
Most consensus guidelines for the past 30 years have held that epinephrine is
the drug of choice and the first drug that should be administered in acute
anaphylaxis. Some state that properly administered epinephrine has no absolute
contraindication in this clinical setting. A committee of anaphylaxis experts
assembled by the World Allergy Organization has examined the evidence from the
medical literature concerning the appropriate use of epinephrine for
anaphylaxis. The committee strongly believes that epinephrine is currently
underused and often dosed suboptimally to treat anaphylaxis, is underprescribed
for potential future self-administration, that most of the reasons proposed to
withhold its clinical use are flawed, and that the therapeutic benefits of
epinephrine exceed the risk when given in appropriate intramuscular doses.
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Bos JM, Ackerman MJ. Arrhythmias: Epinephrine test for sudden cardiac death--is it too early? Nat Rev Cardiol 2012; 9:675-6. [PMID: 23149838 DOI: 10.1038/nrcardio.2012.155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Adler A, van der Werf C, Postema PG, Rosso R, Bhuiyan ZA, Kalman JM, Vohra JK, Guevara-Valdivia ME, Marquez MF, Halkin A, Benhorin J, Antzelevitch C, Wilde AAM, Viskin S. The phenomenon of "QT stunning": the abnormal QT prolongation provoked by standing persists even as the heart rate returns to normal in patients with long QT syndrome. Heart Rhythm 2012; 9:901-8. [PMID: 22300664 DOI: 10.1016/j.hrthm.2012.01.026] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Indexed: 01/08/2023]
Abstract
BACKGROUND Patients with long QT syndrome (LQTS) have inadequate shortening of the QT interval in response to the sudden heart rate accelerations provoked by standing-a phenomenon of diagnostic value. We now validate our original observations in a cohort twice as large. We also describe that this abnormal QT-interval response persists as the heart rate acceleration returns to baseline. OBJECTIVES To describe a novel observation, termed "QT stunning" and to validate previous observations regarding the "QT-stretching" phenomenon in patients with LQTS by using our recently described "standing test." METHODS The electrocardiograms of 108 patients with LQTS and 112 healthy subjects were recorded in the supine position. Subjects were then instructed to stand up quickly and remain standing for 5 minutes during continuous electrocardiographic recording. The corrected QT interval was measured at baseline (QTc(base)), when heart rate acceleration without appropriate QT-interval shortening leads to maximal QT stretching (QTc(stretch)) and upon return of heart rate to baseline (QTc(return)). RESULTS QTc(stretch) lengthened significantly more in patients with LQTS (103 ± 80 ms vs 66 ± 40 ms in controls; P <.001) and so did QTc(return) (28 ± 48 ms for patients with LQTS vs -3 ± 32 ms for controls; P <.001). Using a sensitivity cutoff of 90%, the specificity for diagnosing LQTS was 74% for QTc(base), 84% for QTc(return), and 87% for QTc(stretch). CONCLUSIONS The present study extends our previous findings on the abnormal response of the QT interval in response to standing in patients with LQTS. Our study also shows that this abnormal response persists even after the heart rate slows back to baseline.
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Affiliation(s)
- Arnon Adler
- Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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21
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Abstract
The coordinated generation and propagation of action potentials within cardiomyocytes creates the intrinsic electrical stimuli that are responsible for maintaining the electromechanical pump function of the human heart. The synchronous opening and closing of cardiac Na(+), Ca(2+), and K(+) channels corresponds with the activation and inactivation of inward depolarizing (Na(+) and Ca(2+)) and outward repolarizing (K(+)) currents that underlie the various phases of the cardiac action potential (resting, depolarization, plateau, and repolarization). Inherited mutations in pore-forming α subunits and accessory β subunits of cardiac K(+) channels can perturb the atrial and ventricular action potential and cause various cardiac arrhythmia syndromes, including long QT syndrome, short QT syndrome, Brugada syndrome, and familial atrial fibrillation. In this Review, we summarize the current understanding of the molecular and cellular mechanisms that underlie K(+)-channel-mediated arrhythmia syndromes. We also describe translational advances that have led to the emerging role of genetic testing and genotype-specific therapy in the diagnosis and clinical management of individuals who harbor pathogenic mutations in genes that encode α or β subunits of cardiac K(+) channels.
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22
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Wu J, Zhang Y, Zhang X, Cheng L, Lammers WJ, Grace AA, Fraser JA, Zhang H, Huang CLH, Lei M. Altered sinoatrial node function and intra-atrial conduction in murine gain-of-function Scn5a+/ΔKPQ hearts suggest an overlap syndrome. Am J Physiol Heart Circ Physiol 2012; 302:H1510-23. [PMID: 22287583 PMCID: PMC3330789 DOI: 10.1152/ajpheart.00357.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mutations in SCN5A, the gene encoding the pore-forming subunit of cardiac Na+ channels, cause a spectrum of arrhythmic syndromes. Of these, sinoatrial node (SAN) dysfunction occurs in patients with both loss- and gain-of-function SCN5A mutations. We explored for corresponding alterations in SAN function and intracardiac conduction and clarified possible mechanisms underlying these in an established mouse long QT syndrome type 3 model carrying a mutation equivalent to human SCN5A-ΔKPQ. Electrophysiological characterizations of SAN function in living animals and in vitro sinoatrial preparations were compared with cellular SAN and two-dimensional tissue models exploring the consequences of Scn5a+/ΔKPQ mutations. Scn5a+/ΔKPQ mice showed prolonged electrocardiographic QT and corrected QT intervals confirming long QT phenotypes. They showed frequent episodes of sinus bradycardia, sinus pause/arrest, and significantly longer sinus node recovery times, suggesting compromised pacemaker activity compared with wild-type mice. Electrocardiographic waveforms suggested depressed intra-atrial, atrioventricular node, and intraventricular conduction in Scn5a+/ΔKPQ mice. Isolated Scn5a+/ΔKPQ sinoatrial preparations similarly showed lower mean intrinsic heart rates and overall slower conduction through the SAN to the surrounding atrium than did wild-type preparations. Computer simulations of both single SAN cells as well as two-dimensional SAN-atrial models could reproduce the experimental observations of impaired pacemaker and sinoatrial conduction in terms of changes produced by both augmented tail and reduced total Na+ currents, respectively. In conclusion, the gain-of-function long QT syndrome type 3 murine Scn5a+/ΔKPQ cardiac system, in overlap with corresponding features reported in loss-of-function Na+ channel mutations, shows compromised SAN pacemaker and conduction function explicable in modeling studies through a combination of augmented tail and reduced peak Na+ currents.
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Affiliation(s)
- Jingjing Wu
- Department of Cardiovascular Diseases, Union Hospital, Huazhong University of Sciences and Technology, Wuhan, Peoples' Republic of China
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Hekkala AM, Swan H, Viitasalo M, Väänänen H, Toivonen L. Epinephrine bolus test in detecting long QT syndrome mutation carriers with indeterminable electrocardiographic phenotype. Ann Noninvasive Electrocardiol 2011; 16:172-9. [PMID: 21496168 DOI: 10.1111/j.1542-474x.2011.00426.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND In long QT syndrome (LQTS), prolonged and heterogeneous ventricular repolarization predisposes to serious arrhythmias. We examined how QT intervals are modified by epinephrine bolus in mutation carriers of three major LQTS subtypes with indefinite QT interval. METHODS Genotyped, asymptomatic subjects with LQTS type 1 (LQT1; n = 10; four different KCNQ1 mutations), type 2 (LQT2; n = 10; three different HERG mutations), and type 3 (LQT3; n = 10; four different SCN5A mutations), and healthy volunteers (n = 15) were examined. Electrocardiogram was recorded with body surface potential mapping system. After an epinephrine 0.04 μg/kg bolus QT end, QT apex, and T-wave peak-to-end (Tpe) intervals were determined automatically as average of 12 precordial leads. Standard deviation (SD) of the 12 channels was calculated. RESULTS Heart rate increased 26 ± 10 bpm with epinephrine bolus, and similarly in all groups. QT end interval lengthened, and QT apex interval shortened in LQTS and normals, leading to lengthening of Tpe interval. However, the lengthening in Tpe was larger in LQTS than in normals (mean 32 vs 18 ms; P < 0.05) and SD of QT apex increased more in LQTS than in normals (mean 23 vs 7 ms; P < 0.01). The increase in Tpe was most pronounced in LQT2, and in SD of QT apex in LQT1 and LQT2. CONCLUSIONS Abrupt adrenergic stimulation with a moderate dose of exogenous epinephrine affects ventricular repolarization in genotype-specific fashion facilitating distinction from normals. This delicate modification may help in diagnosing electrocardiographically silent mutation carriers when screening LQTS family members.
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Affiliation(s)
- Anna-Mari Hekkala
- Helsinki University Hospital, Department of Cardiology, Helsinki, Finland.
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24
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Nof E, Barajas-Martinez H, Eldar M, Urrutia J, Caceres G, Rosenfeld G, Bar-Lev D, Feinberg M, Burashnikov E, Casis O, Hu D, Glikson M, Antzelevitch C. LQT5 masquerading as LQT2: a dominant negative effect of KCNE1-D85N rare polymorphism on KCNH2 current. Europace 2011; 13:1478-83. [PMID: 21712262 DOI: 10.1093/europace/eur184] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS KCNE1 encodes an auxiliary subunit of cardiac potassium channels. Loss-of-function variations in this gene have been associated with the LQT5 form of the long QT syndrome (LQTS), secondary to reduction of I(Ks) current. We present a case in which a D85N rare polymorphism in KCNE1 is associated with an LQT2 phenotype. METHODS AND RESULTS An 11-year old competitive athlete presented with mild bradycardia and a QTc interval of 470 ms. An LQT2 phenotype, consisting of low-voltage bifid T waves, was evident in the right precordial electrocardiogram leads. During the tachycardia phase following adenosine, QTc increased to 620 ms. Genetic analysis revealed a rare heterozygous polymorphism in KCNE1 predicting the substitution of asparagine for aspartic acid at position 85 of minK (D85N). Patch clamp experiments showed that KCNE1-D85N, when co-expressed with KCNH2 in TSA201 cells, significantly reduced I(Kr). Homozygous co-expression of the mutant with KCNH2 reduced I(Kr) tail current by 85%, whereas heterozygous co-expression reduced the current by 52%, demonstrating for the first time a dominant-negative effect of D85N to reduce I(Kr). Co-expression of the mutant with KCNQ1, either homozygously or heterozygously, produced no change in I(Ks). CONCLUSIONS Our results suggest that a rare polymorphism KCNE1-D85N underlies the development of an LQT2 phenotype in this young athlete by interacting with KCNH2 to cause a dominant-negative effect to reduce I(Kr). Our data provide further evidence in support of the promiscuity of potassium channel β subunits in modulating the function of multiple potassium channels leading to a diversity of clinical phenotypes.
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Affiliation(s)
- Eyal Nof
- Masonic Medical Research Laboratory, Utica, NY, USA
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Gemma LW, Ward GM, Dettmer MM, Ball JL, Leo PJ, Doria DN, Kaufman ES. β-blockers protect against dispersion of repolarization during exercise in congenital long-QT syndrome type 1. J Cardiovasc Electrophysiol 2011; 22:1141-6. [PMID: 21635612 DOI: 10.1111/j.1540-8167.2011.02091.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION β-Blocker therapy reduces syncope and sudden death in long-QT syndrome type 1 (LQT1), but the mechanism of protection is incompletely understood. This study tested the hypothesis that β-blockade reduces QT prolongation and dispersion of repolarization, measured as the T peak-to-end interval (T(pe) ), during exercise and recovery in LQT1 patients. METHODS AND RESULTS QT and T(pe) were measured in 10 LQT1 patients (33 ± 13 years) and 35 normal subjects (32 ± 12 years) during exercise tests on and off β-blockade. In LQT1 patients, β-blockade reduced QT (391 ± 25 milliseconds vs 375 ± 26 milliseconds, P = 0.04 during exercise; 419 ± 41 milliseconds vs 391 ± 39 milliseconds, P = 0.02 during recovery) and markedly reduced T(pe) (91 ± 26 milliseconds vs 67 ± 19 milliseconds, P = 0.03 during exercise; 103 ± 26 milliseconds vs 78 ± 11 milliseconds, P = 0.02 during recovery). In contrast, in normal subjects, β-blockade had no effect on QT (320 ± 17 milliseconds vs 317 ± 16 milliseconds, P = 0.29 during exercise; 317 ± 13 milliseconds vs 315 ± 14 milliseconds, P = 0.15 during recovery) and mildly reduced T(pe) (69 ± 13 milliseconds vs 61 ± 11 milliseconds, P = 0.01 during exercise; 77 ± 19 milliseconds vs. 68 ± 14 milliseconds, P < 0.001 during recovery). CONCLUSION In LQT1 patients, β-blockers reduced QT and T(pe) during exercise and recovery, supporting the theory that β-blocker therapy protects LQT1 patients by reducing dispersion of repolarization during exercise and recovery.
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Affiliation(s)
- Lee W Gemma
- Heart and Vascular Research Center, MetroHealth Campus of Case Western Reserve University, Cleveland, Ohio, USA
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Findler M, Birger A, Diamant S, Viskin S. Effects of head-up tilt-table test on the QT interval. Ann Noninvasive Electrocardiol 2010; 15:245-9. [PMID: 20645967 DOI: 10.1111/j.1542-474x.2010.00371.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The QT interval shortens in response to sympathetic stimulation and its response to epinephrine infusion (in healthy individuals and patients with long QT syndrome) has been thoroughly studied. Head-up tilt-table (HUT) testing is an easy way to achieve brisk sympathetic stimulation. Yet, little is known about the response of the QT interval to HUT. METHODS We reviewed the electrocardiograms of HUT tests performed at our institution and compare the heart rate, QT, and QTc obtained immediately after HUT with the rest values. RESULTS The study group consisted of 41 patients (27 females and 14 males) aged 23.9 +/- 8.4 years. Head-up tilting led to a significant shortening of the RR interval (from 825 +/- 128 msec at rest phase to 712 +/- 130 msec in the upward tilt phase, P < 0.001) but only to a moderate shortening of the QT interval (from 363.7 +/- 27.9 msec during rest to 355 +/- 30.3 msec during upward tilt, P = 0.001). Since the RR interval shortened more than the QT interval, the QTc actually increased (from 403 +/- 21.5 msec during rest phase to 423.2 +/- 27.4 msec during upward tilt, P < 0.001). The QTc value measured for the upward tilt position was longer than the resting QTc value in 33 of 41 patients. Of those, 4 male patients and 2 female patients developed upward-tilt QTc values above what would be considered abnormal at rest. CONCLUSIONS During HUT the QT shortens less than the RR interval. Consequently, the QTc increases during head-up tilt.
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Affiliation(s)
- Michael Findler
- Tel-Aviv Sourasky Medical Center, Tel Aviv University, Israel
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Aziz F, Penupolu S, Doddi S, Togonu-Bickersteth B, Ameen A. Congenital long QT syndrome: A case report. J Thorac Dis 2010; 2:185-8. [PMID: 22263042 DOI: 10.3978/j.issn.2072-1439.2010.02.03.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Accepted: 08/25/2010] [Indexed: 11/14/2022]
Abstract
The congenital long QT syndrome (LQTS) is characterized by abnormally prolonged ventricular repolarization due to inherited defects in cardiac sodium and potassium channels, which predispose the patients to syncope, seizure like activity, ventricular arrhythmias, and sudden cardiac death. Early diagnosis and preventive treatment are instrumental in preventing sudden cardiac deaths in patients with the congenital LQTS. The diagnostic criteria for congenital LQTS are based on certain electrocardiographic findings, clinical findings and findings of epinephrine stress test. Recently genotype specific electrocardiographic pattern in the congenital LQTS has also been described. Recent studies suggest feasibility of genotype specific treatment of LQTS and, in near future, mutation specific treatment will probably become a novel approach to this potentially fatal syndrome. We describe one case that fulfilled the electrocardiographic, historical diagnostic criteria and epinephrine stress test suggestive of LQT syndrome.
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Affiliation(s)
- Fahad Aziz
- Resident Internal Medicine, Jersey City Medical Center, NJ, USA
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Chattha IS, Sy RW, Yee R, Gula LJ, Skanes AC, Klein GJ, Bennett MT, Krahn AD. Utility of the recovery electrocardiogram after exercise: a novel indicator for the diagnosis and genotyping of long QT syndrome? Heart Rhythm 2010; 7:906-11. [DOI: 10.1016/j.hrthm.2010.03.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 03/03/2010] [Indexed: 11/28/2022]
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Hekkala AM, Viitasalo M, Vaananen H, Swan H, Toivonen L. Abnormal repolarization dynamics revealed in exercise test in long QT syndrome mutation carriers with normal resting QT interval. Europace 2010; 12:1296-301. [DOI: 10.1093/europace/euq184] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Viskin S, Postema PG, Bhuiyan ZA, Rosso R, Kalman JM, Vohra JK, Guevara-Valdivia ME, Marquez MF, Kogan E, Belhassen B, Glikson M, Strasberg B, Antzelevitch C, Wilde AAM. The response of the QT interval to the brief tachycardia provoked by standing: a bedside test for diagnosing long QT syndrome. J Am Coll Cardiol 2010; 55:1955-61. [PMID: 20116193 DOI: 10.1016/j.jacc.2009.12.015] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2009] [Revised: 12/07/2009] [Accepted: 12/21/2009] [Indexed: 11/17/2022]
Abstract
OBJECTIVES This study was undertaken to determine whether the short-lived sinus tachycardia that occurs during standing will expose changes in the QT interval that are of diagnostic value. BACKGROUND The QT interval shortens during heart rate acceleration, but this response is not instantaneous. We tested whether the transient, sudden sinus tachycardia that occurs during standing would expose abnormal QT interval prolongation in patients with long QT syndrome (LQTS). METHODS Patients (68 with LQTS [LQT1 46%, LQT2 41%, LQT3 4%, not genotyped 9%] and 82 control subjects) underwent a baseline electrocardiogram (ECG) while resting in the supine position and were then asked to get up quickly and stand still during continuous ECG recording. The QT interval was studied at baseline and during maximal sinus tachycardia, maximal QT interval prolongation, and maximal QT interval stretching. RESULTS In response to brisk standing, patients and control subjects responded with similar heart rate acceleration of 28 +/- 10 beats/min (p = 0.261). However, the response of the QT interval to this tachycardia differed: on average, the QT interval of controls shortened by 21 +/- 19 ms whereas the QT interval of LQTS patients increased by 4 +/- 34 ms (p < 0.001). Since the RR interval shortened more than the QT interval, during maximal tachycardia the corrected QT interval increased by 50 +/- 30 ms in the control group and by 89 +/- 47 ms in the LQTS group (p < 0.001). Receiver-operating characteristic curves showed that the test adds diagnostic value. The response of the QT interval to brisk standing was particularly impaired in patients with LQT2. CONCLUSIONS Evaluation of the response of the QT interval to the brisk tachycardia induced by standing provides important information that aids in the diagnosis of LQTS.
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Affiliation(s)
- Sami Viskin
- Department of Cardiology, Tel-Aviv Medical Center, Tel Aviv University, Tel Aviv, Israel.
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Kim JH, Park SH, Kim KH, Choi WS, Kang JK, Kim NY, Cho Y. Epinephrine-Induced Polymorphic Ventricular Tachycardia in a Patient With Congenital Long QT Syndrome. Korean Circ J 2009; 39:386-8. [PMID: 19949624 PMCID: PMC2771827 DOI: 10.4070/kcj.2009.39.9.386] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Accepted: 06/17/2009] [Indexed: 11/11/2022] Open
Abstract
A 24-year-old woman presented to the department of plastic surgery for surgical excision of a nevus on her nose. Although her history failed to reveal any cardiac disease, her pre-operative electrocardiogram (ECG) showed an extremely prolonged QT interval of up to 528 msec. Repeated history-taking after admission revealed three syncopal episodes associated with both physical and emotional stress, and because the two-dimensional echocardiography and exercise ECG test were normal except for the prolonged QT interval, an epinephrine test was done to assess QT interval changes after an epinephrine infusion. Immediately after a bolus injection of epinephrine (0.1 µg/kg), marked prolongation of the QT interval developed, followed by polymorphic ventricular tachycardia which was immediately terminated with direct current shock, resulting in the diagnosis of a long QT syndrome (LQTS), probably type 1. Gene studies were recommended, but declined by the patient and her family. She was instructed to avoid competitive sports, and a β-blocker was prescribed after which she remained symptom-free.
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Affiliation(s)
- Jae Hee Kim
- Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Korea
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Abstract
The long QT syndrome (LQTS) is a rare, congenital or acquired disease, which may lead to fatal cardiac arrhythmias (torsade de pointes, TdP). In all LQTS subtypes, TdPs are caused by disturbances in cardiac ion channels. Diagnosis is made using clinical, anamnestic and electrocardiographic data. Triggers of TdPs are numerous and should be avoided perioperatively. Sufficient sedation and preoperative correction of electrolyte imbalances are essential. Volatile anaesthetics and antagonists of muscle relaxants should be avoided and high doses of local anaesthetics are not recommended to date. Propofol is safe for anaesthesia induction and maintenance. The acute therapy of TdPs with cardiovascular depression should be performed in accordance with the guidelines for advanced cardiac life support and includes cardioversion/defibrillation and magnesium. Torsades de pointes may be associated with bradycardia or tachycardia resulting in specific therapeutic and prophylactic measures.
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Affiliation(s)
- S Rasche
- Klinik und Poliklinik für Anästhesiologie und Intensivtherapie, Universitätsklinikum Carl Gustav Carus, Technische Universität, Dresden.
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Abstract
The hereditary Long QT syndrome (LQTS) is a genetic channelopathy with variable penetrance that is associated with increased propensity for polymorphic ventricular tachyarrhythmias and sudden cardiac death in young individuals with normal cardiac morphology. The diagnosis of this genetic disorder relies on a constellation of electrocardiographic, clinical, and genetic factors. Accumulating data from recent studies indicate that the clinical course of affected LQTS patients is time-dependent and age-specific, demonstrating important gender differences among age groups. Risk assessment should consider age-gender interactions, prior syncopal history, QT-interval duration, and genetic factors. Beta-blockers constitute the mainstay therapy for LQTS, while left cardiac sympathetic denervation and implantation of a cardioverter defibrillator should be considered in patients who remain symptomatic despite beta-blocker therapy. Current and ongoing studies are also evaluating genotype-specific therapies that may reduce the risk for life-threatening cardiac events in high-risk LQTS patients.
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Patel C, Antzelevitch C. Pharmacological approach to the treatment of long and short QT syndromes. Pharmacol Ther 2008; 118:138-51. [PMID: 18378319 DOI: 10.1016/j.pharmthera.2008.02.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 02/05/2008] [Indexed: 12/30/2022]
Abstract
Inherited channelopathies have received increasing attention in recent years. The past decade has witnessed impressive progress in our understanding of the molecular and cellular basis of arrhythmogenesis associated with inherited channelopathies. An imbalance in ionic forces induced by these channelopathies affects the duration of ventricular repolarization and amplifies the intrinsic electrical heterogeneity of the myocardium, creating an arrhythmogenic milieu. Today, many of the channelopathies have been linked to mutations in specific genes encoding either components of ion channels or membrane or regulatory proteins. Many of the channelopathies are genetically heterogeneous with a variable degree of expression of the disease. Defining the molecular basis of channelopathies can have a profound impact on patient management, particularly in cases in which genotype-specific pharmacotherapy is available. The long QT syndrome (LQTS) is one of the first identified and most studied channelopathies where abnormal prolongation of ventricular repolarization predisposes an individual to life threatening ventricular arrhythmia called Torsade de Pointes. On the other hand of the spectrum, molecular defects favoring premature repolarization lead to Short QT syndrome (SQTS), a recently described inherited channelopathy. Both of these channelopathies are associated with a high risk of sudden cardiac death due to malignant ventricular arrhythmia. Whereas pharmacological therapy is first line treatment for LQTS, defibrillators are considered as primary treatment for SQTS. This review provides a comprehensive review of the molecular genetics, clinical features, genotype-phenotype correlations and genotype-specific approach to pharmacotherapy of these two mirror-image channelopathies, SQTS and LQTS.
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Brunner M, Peng X, Liu GX, Ren XQ, Ziv O, Choi BR, Mathur R, Hajjiri M, Odening KE, Steinberg E, Folco EJ, Pringa E, Centracchio J, Macharzina RR, Donahay T, Schofield L, Rana N, Kirk M, Mitchell GF, Poppas A, Zehender M, Koren G. Mechanisms of cardiac arrhythmias and sudden death in transgenic rabbits with long QT syndrome. J Clin Invest 2008; 118:2246-59. [PMID: 18464931 DOI: 10.1172/jci33578] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 03/19/2008] [Indexed: 11/17/2022] Open
Abstract
Long QT syndrome (LQTS) is a heritable disease associated with ECG QT interval prolongation, ventricular tachycardia, and sudden cardiac death in young patients. Among genotyped individuals, mutations in genes encoding repolarizing K+ channels (LQT1:KCNQ1; LQT2:KCNH2) are present in approximately 90% of affected individuals. Expression of pore mutants of the human genes KCNQ1 (KvLQT1-Y315S) and KCNH2 (HERG-G628S) in the rabbit heart produced transgenic rabbits with a long QT phenotype. Prolongations of QT intervals and action potential durations were due to the elimination of IKs and IKr currents in cardiomyocytes. LQT2 rabbits showed a high incidence of spontaneous sudden cardiac death (>50% at 1 year) due to polymorphic ventricular tachycardia. Optical mapping revealed increased spatial dispersion of repolarization underlying the arrhythmias. Both transgenes caused downregulation of the remaining complementary IKr and IKs without affecting the steady state levels of the native polypeptides. Thus, the elimination of 1 repolarizing current was associated with downregulation of the reciprocal repolarizing current rather than with the compensatory upregulation observed previously in LQTS mouse models. This suggests that mutant KvLQT1 and HERG interacted with the reciprocal wild-type alpha subunits of rabbit ERG and KvLQT1, respectively. These results have implications for understanding the nature and heterogeneity of cardiac arrhythmias and sudden cardiac death.
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Affiliation(s)
- Michael Brunner
- Innere Medizin III-Kardiologie und Angiologie, Universitätsklinikum Freiburg, Freiburg, Germany
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Kemp SF, Lockey RF, Simons FER. Epinephrine: the drug of choice for anaphylaxis-a statement of the world allergy organization. World Allergy Organ J 2008; 1:S18-26. [PMID: 23282530 PMCID: PMC3666145 DOI: 10.1097/wox.0b013e31817c9338] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Anaphylaxis is an acute and potentially lethal multisystem allergic reaction. Most consensus guidelines for the past 30 years have held that epinephrine is the drug of choice and the first drug that should be administered in acute anaphylaxis. Some state that properly administered epinephrine has no absolute contraindication in this clinical setting. A committee of anaphylaxis experts assembled by the World Allergy Organization has examined the evidence from the medical literature concerning the appropriate use of epinephrine for anaphylaxis. The committee strongly believes that epinephrine is currently underused and often dosed suboptimally to treat anaphylaxis, is underprescribed for potential future self-administration, that most of the reasons proposed to withhold its clinical use are flawed, and that the therapeutic benefits of epinephrine exceed the risk when given in appropriate intramuscular doses.
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Effect of autonomic blockade on ventricular repolarization shortening: Response to behavioral stimulus in paced dogs. Auton Neurosci 2008; 140:66-71. [PMID: 18499531 DOI: 10.1016/j.autneu.2008.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 04/07/2008] [Accepted: 04/10/2008] [Indexed: 11/23/2022]
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Jeyaraj D, Abernethy DP, Natarajan RN, Dettmer MM, Dikshteyn M, Meredith DM, Patel K, Allareddy RR, Lewis SA, Kaufman ES. IKr channel blockade to unmask occult congenital long QT syndrome. Heart Rhythm 2008; 5:2-7. [DOI: 10.1016/j.hrthm.2007.08.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Medeiros-Domingo A, Iturralde-Torres P, Ackerman MJ. Clínica y genética en el síndrome de QT largo. Rev Esp Cardiol 2007. [DOI: 10.1157/13108280] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Paavonen KJ, Swan H, Piippo K, Laitinen P, Fodstad H, Sarna S, Toivonen L, Kontula K, Viitasalo M. Beta1-adrenergic receptor polymorphisms, QTc interval and occurrence of symptoms in type 1 of long QT syndrome. Int J Cardiol 2006; 118:197-202. [PMID: 17023080 DOI: 10.1016/j.ijcard.2006.06.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 05/24/2006] [Accepted: 06/02/2006] [Indexed: 11/28/2022]
Abstract
BACKGROUND The most prevalent LQT1 form of inherited long QT syndrome is caused by mutations of the KCNQ1 gene resulting repolarizing I(Ks) potassium current to decrease and the QT interval to prolong. As abrupt sympathetic activation triggers ventricular arrhythmias that may cause syncopal attacks and sudden death in LQT1 patients, we investigated whether two known beta1-adrenergic receptor polymorphisms were associated with the duration of QT interval or history of symptoms in LQT1. METHODS We determined beta1-adrenergic receptor polymorphisms (Ser49Gly and Arg389Gly) in 168 LQT1 patients. We also reviewed each patient's clinical records on the history of long QT syndrome-related symptoms and measured QT intervals from baseline ECG in each subject and from an exercise test ECG in 55 LQT1 patients. RESULTS Patients with the homozygous Arg389Arg genotype tended to have shorter and those with the Ser49Ser genotype longer QT intervals than patients with other genotypes, but neither polymorphism studied alone affected the risk of symptoms. In contrast, adjusted odds ratio for the history of symptoms was 4.9 (95% CI 1.18 to 20.3) in patients homozygous for both Ser49 and Arg389. These double homozygous patients showed similar QT intervals as the rest of the LQT1 cohort. CONCLUSIONS In this relatively small study, double homozygosity for Arg389 and Ser49 of the human beta1-adrenergic receptor associated with the risk of symptoms in LQT1. The association between these beta1-adrenergic receptor polymorphisms and the symptom history in LQT1 is not mediated via QT interval duration.
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Tester DJ, Kopplin LJ, Will ML, Ackerman MJ. Spectrum and prevalence of cardiac ryanodine receptor (RyR2) mutations in a cohort of unrelated patients referred explicitly for long QT syndrome genetic testing. Heart Rhythm 2006; 2:1099-105. [PMID: 16188589 DOI: 10.1016/j.hrthm.2005.07.012] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Accepted: 07/13/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND Mutations in the RyR2-encoded cardiac ryanodine receptor/calcium release channel cause type 1 catecholaminergic polymorphic ventricular tachycardia (CPVT1). OBJECTIVES Because CPVT and concealed long QT syndrome (LQTS) phenotypically mimic one other, we sought to determine the spectrum and prevalence of RyR2 mutations in a cohort of unrelated patients who were referred specifically for LQTS genetic testing. METHODS Using denaturing high-performance liquid chromatography and direct DNA sequencing, targeted mutational analysis of 23 RyR2 exons previously implicated in CPVT1 was performed on genomic DNA from 269 unrelated patients (180 females, average age at diagnosis 24 +/- 17 years) who were referred to Mayo Clinic's Sudden Death Genomics Laboratory for LQTS genetic testing. Previously, comprehensive mutational analysis of the five LQTS-associated cardiac channel genes proved negative for this entire subset of patients now designated as "genotype-negative" LQTS referrals. RESULTS Fifteen distinct RyR2 mutations (14 missense, 1 duplication/insertion, 12 novel) were found in 17 (6.3%) of 269 patients. None of these mutations were present in 400 reference alleles. Two mutations localized to the calstabin-2 (FKBP12.6) binding domain. Upon review of the clinical records, the referral diagnosis for all 17 patients was "atypical" or "borderline" LQTS. CONCLUSION Putative pathogenic CPVT1-causing mutations in RyR2 were detected in 6% of unrelated, genotype-negative LQTS referrals. These findings suggest that CPVT may be underrecognized among physicians referring patients because of a suspected channelopathy. A diagnosis of "atypical LQTS" may warrant consideration of CPVT and analysis of RyR2 if the standard cardiac channel gene screen for LQTS is negative.
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Affiliation(s)
- David J Tester
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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Abstract
Long QT syndrome, a rare genetic disorder associated with life-threatening arrhythmias, has provided a wealth of information about fundamental mechanisms underlying human cardiac electrophysiology that has come about because of truly collaborative interactions between clinical and basic scientists. Our understanding of the mechanisms that control the critical plateau and repolarization phases of the human ventricular action potential has been raised to new levels through these studies, which have clarified the manner in which both potassium and sodium channels regulate this critical period of electrical activity.
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Affiliation(s)
- Arthur J Moss
- Heart Research Follow-up Program, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
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Viskin S, Rosso R, Rogowski O, Belhassen B, Levitas A, Wagshal A, Katz A, Fourey D, Zeltser D, Oliva A, Pollevick GD, Antzelevitch C, Rozovski U. Provocation of sudden heart rate oscillation with adenosine exposes abnormal QT responses in patients with long QT syndrome: a bedside test for diagnosing long QT syndrome. Eur Heart J 2005; 27:469-75. [PMID: 16105845 PMCID: PMC1474076 DOI: 10.1093/eurheartj/ehi460] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS As arrhythmias in the long QT syndrome (LQTS) are triggered by heart rate deceleration or acceleration, we speculated that the sudden bradycardia and subsequent tachycardia that follow adenosine injection would unravel QT changes of diagnostic value in patients with LQTS. METHODS AND RESULTS Patients (18 LQTS and 20 controls) received intravenous adenosine during sinus rhythm. Adenosine was injected at incremental doses until atrioventricular block or sinus pauses lasting 3 s occurred. The QT duration and morphology were studied at baseline and at the time of maximal bradycardia and subsequent tachycardia. Despite similar degree of adenosine-induced bradycardia (longest R-R 1.7+/-0.7 vs. 2.2+/-1.3 s for LQTS and controls, P=NS), the QT interval of LQT patients increased by 15.8+/-13.1%, whereas the QT of controls increased by only 1.5+/-6.7% (P<0.001). Similarly, despite similar reflex tachycardia (shortest R-R 0.58+/-0.07 vs. 0.55+/-0.07 s for LQT patients and controls, P=NS), LQTS patients developed greater QT prolongation (QTc=569+/-53 vs. 458+/-58 ms for LQT patients and controls, P<0.001). The best discriminator was the QTc during maximal bradycardia. Notched T-waves were observed in 72% of LQT patients but in only 5% of controls during adenosine-induced bradycardia (P<0.001). CONCLUSION By provoking transient bradycardia followed by sinus tachycardia, this adenosine challenge test triggers QT changes that appear to be useful in distinguishing patients with LQTS from healthy controls.
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Affiliation(s)
- Sami Viskin
- Department of Cardiology, Tel-Aviv Sourasky Medical Center, Sackler-School of Medicine, Tel Aviv University, Weizman 6, Tel Aviv 64239, Israel.
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Khositseth A, Tester DJ, Will ML, Bell CM, Ackerman MJ. Identification of a common genetic substrate underlying postpartum cardiac events in congenital long QT syndrome. Heart Rhythm 2005; 1:60-4. [PMID: 15851119 DOI: 10.1016/j.hrthm.2004.01.006] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2003] [Accepted: 01/27/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVES The aim of this study was to elucidate the genetic basis for long QT syndrome (LQTS) in patients with a personal or family history of postpartum cardiac events. BACKGROUND The postpartum period is a time of increased arrhythmogenic susceptibility in women with LQTS. METHODS Between August 1997 and May 2003, 388 unrelated patients (260 females, average age at diagnosis, 23 years, and average QTc, 482 ms) were referred to Mayo Clinic's Sudden Death Genomics Laboratory for LQTS genetic testing. Comprehensive mutational analysis of the 5 LQTS-causing channel genes was performed. The postpartum period was defined as the 20 weeks after delivery. Cardiac events included sudden cardiac death, aborted cardiac arrest, and syncope. The presence of a personal and/or family history of cardiac events during postpartum period was determined by review of the medical records and/or phone interviews and was blinded to the status of genetic testing. RESULTS Fourteen patients (3.6% of cohort) had personal (n = 4) and/or family history (n = 11) of cardiac events during the defined postpartum period. Thirteen of 14 patients (93%) possessed an LQT2 mutation and 1 had an LQT1 mutation. Postpartum cardiac events were found more commonly in patients with LQT2 (13 of 80, 16%) than in patients with LQT1 (1 of 103, <1%, P = .0001). CONCLUSIONS There is a relatively gene-specific molecular basis underlying cardiac events during the postpartum period in LQTS. Along with previous gene-specific associations involving swimming and LQT1 as well as auditory triggers and LQT2, this association between postpartum cardiac events and LQT2 can facilitate strategic genotyping.
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Affiliation(s)
- Anant Khositseth
- Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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Lee SH, Shin DG, Hong GR, Park JS, Kim YJ, Shim BS. Right ventricular outflow tract tachycardia and polymorphic ventricular tachycardia. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2005; 28:231-4. [PMID: 15733184 DOI: 10.1111/j.1540-8159.2005.09349.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sang-Hee Lee
- Cardiovascular Division, Yeungnam University Hospital, Daegu, Republic of Korea
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Shimizu W, Noda T, Takaki H, Nagaya N, Satomi K, Kurita T, Suyama K, Aihara N, Sunagawa K, Echigo S, Miyamoto Y, Yoshimasa Y, Nakamura K, Ohe T, Towbin JA, Priori SG, Kamakura S. Diagnostic value of epinephrine test for genotyping LQT1, LQT2, and LQT3 forms of congenital long QT syndrome. Heart Rhythm 2005; 1:276-83. [PMID: 15851169 DOI: 10.1016/j.hrthm.2004.04.021] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Accepted: 04/14/2004] [Indexed: 12/24/2022]
Abstract
OBJECTIVES The aim of this study was to test the hypothesis that epinephrine test may have diagnostic value for genotyping LQT1, LQT2, and LQT3 forms of congenital long QT syndrome (LQTS). BACKGROUND A differential response of dynamic QT interval to epinephrine infusion between LQT1, LQT2, and LQT3 syndromes has been reported, indicating the potential diagnostic value of the epinephrine test for genotyping the three forms. METHODS The responses of 12-lead ECG parameters to epinephrine were retrospectively examined in 15 LQT1, 10 LQT2, 8 LQT3, and 10 healthy volunteers to select the best ECG criteria for separating the four groups. The epinephrine test then was prospectively conducted in 42 probands clinically affected with LQTS, their 67 family members, and 10 new volunteers. The best criteria were applied in a blinded fashion to prospectively separate a different group of 31 LQT1, 23 LQT2, 6 LQT3, and 30 Control patients (10 genotype-negative LQT1, 10 genotype-negative LQT2 family members, and 10 volunteers). RESULTS The sensitivity (penetrance) by ECG diagnostic criteria was lower in LQT1 (68%) than in LQT2 (83%) or LQT3 (83%) before epinephrine and was improved with steady-state epinephrine in LQT1 (87%) and LQT2 (91%) but not in LQT3 (83%), without the expense of specificity (100%). The sensitivity and specificity to differentiate LQT1 from LQT2 were 97% and 96%, those from LQT3 were 97% and 100%, and those from Control were 97% and 100%, respectively, when Delta mean corrected Q-Tend >/=35 ms at steady state was used. The sensitivity and specificity to differentiate LQT2 from LQT3 or Control were 100% and 100%, respectively, when Delta mean corrected Q-Tend >/=80 ms at peak was used. CONCLUSIONS Epinephrine infusion is a powerful test to predict the genotype of LQT1, LQT2, and LQT3 syndromes as well as to improve the clinical diagnosis of genotype-positive patients, especially those with LQT1 syndrome.
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Affiliation(s)
- Wataru Shimizu
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Japan.
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Khositseth A, Hejlik J, Shen WK, Ackerman MJ. Epinephrine-induced T-wave notching in congenital long QT syndrome. Heart Rhythm 2005; 2:141-6. [PMID: 15851286 DOI: 10.1016/j.hrthm.2004.11.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2004] [Accepted: 11/05/2004] [Indexed: 11/18/2022]
Abstract
OBJECTIVES The purpose of this study was to characterize the effect of epinephrine on T-wave morphology in patients with congenital long QT syndrome (LQTS). BACKGROUND QT prolongation is a paradoxical, LQT1-specific response to low-dose epinephrine infusion. At rest, notched T waves are more common in LQT2. METHODS Thirty subjects with LQT1, 28 with LQT2, and 32 controls were studied using epinephrine provocation. Twelve-lead ECG was recorded continuously, and QT, QTc, and heart rate were obtained during each stage. Blinded to phenotype and genotype, T-wave morphology was classified as normal, biphasic, G1 (notch at or below the apex), or G2 (distinct protuberance above the apex). RESULTS At baseline, 97% LQT1, 71% LQT2, and 94% control had normal T-wave profiles. During epinephrine infusion, G1- and G2-T waves were more common in LQT2 than in LQT1 (75% vs 26%, P = .009). However, epinephrine-induced G1-T waves were present in 34% of control. Epinephrine-precipitated biphasic T waves were observed similarly in all groups: LQT1 (6/30), LQT2 (3/28), and control (4/32). During low-dose epinephrine infusion (< or =0.05 microg/kg/min), G1-T waves occurred more frequently in LQT2 (LQT1: 25% vs 3%; control 9%, P = .02). Low-dose epinephrine-induced G2-T waves were detected exclusively in LQT2 (18%). Low-dose epinephrine elicited G1/G2-T waves in 8 of 15 LQT2 patients with a nondiagnostic baseline QTc. CONCLUSIONS Biphasic and G1-T waves are nonspecific responses to high-dose epinephrine. Changes in T-wave morphology during low-dose epinephrine (<0.05 microg/kg/min) may yield diagnostic information. G2-notched T waves elicited during low-dose epinephrine may unmask some patients with concealed LQT2.
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Affiliation(s)
- Anant Khositseth
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Shimizu W, Aiba T, Antzelevitch C. Specific therapy based on the genotype and cellular mechanism in inherited cardiac arrhythmias. Long QT syndrome and Brugada syndrome. Curr Pharm Des 2005; 11:1561-72. [PMID: 15892662 PMCID: PMC1475802 DOI: 10.2174/1381612053764823] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Seven forms of congenital long QT syndrome (LQTS) caused by mutations in ion channel genes have been identified. Genotype-phenotype correlation in clinical and experimental studies involving arterially-perfused canine left ventricular wedges suggest that beta-blockers are protective in LQT1, less so in LQT2, but not protective in LQT3. A class IB sodium channel blocker, mexiletine, is most effective in abbreviating QT interval in LQT3, but effectively reduces transmural dispersion of repolarization (TDR) and prevents the development of Torsade de Pointes (TdP) in all 3 models, suggesting its potential as an adjunctive therapy in LQT1 and LQT2. High concentrations of intravenous nicorandil, a potassium channel opener, have been shown to be capable of decreasing QT and TDR, and preventing TdP in LQT1 and LQT2 but not in LQT3. The calcium channel blocker, verapamil, has also been suggested as adjunctive therapy for LQT1, LQT2 and possibly LQT3. Experimental data using right ventricular wedge preparations suggest that a prominent transient outward current (I(to))-mediated action potential (AP) notch and a loss of AP dome in epicardium, but not in endocardium, give rise to a transmural voltage gradient, resulting in ST segment elevation and the induction of ventricular fibrillation (VF), characteristics of the Brugada syndrome. Since the maintenance of the AP dome is determined by the balance of currents active at the end of phase 1 of the AP, any intervention that reduces the outward current or boosts inward current at the end of phase 1 may normalize the ST segment elevation and suppress VF. Such interventions are candidates for pharmacological therapy of the Brugada syndrome. The infusion of isoproterenol, a beta-adrenergic stimulant, strongly augments L-type calcium current (I(Ca-L)), and is the first choice for suppressing electrical storms associated with Brugada syndrome. Quinidine, by virtue of its actions to block I(to), has been proposed as adjunctive therapy, with an implantable cardioverter defibrillator as backup. Oral denopamine, atropine or cilostazol all increase ICa-L, and for this reason may be effective in reducing episodes of VF.
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Affiliation(s)
- Wataru Shimizu
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565 Japan.
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Tester DJ, Will ML, Haglund CM, Ackerman MJ. Compendium of cardiac channel mutations in 541 consecutive unrelated patients referred for long QT syndrome genetic testing. Heart Rhythm 2005; 2:507-17. [PMID: 15840476 DOI: 10.1016/j.hrthm.2005.01.020] [Citation(s) in RCA: 430] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Accepted: 01/18/2005] [Indexed: 01/24/2023]
Abstract
OBJECTIVES The purpose of this study was to determine the spectrum and prevalence of cardiac channel mutations among a large cohort of consecutive, unrelated patients referred for long QT syndrome (LQTS) genetic testing. BACKGROUND Congenital LQTS is a primary cardiac channelopathy. More than 300 mutations have been identified in five genes encoding key ion channel subunits. Until the recent release of the commercial clinical genetic test, LQTS genetic testing had been performed in research laboratories during the past decade. METHODS A cardiac channel gene screen for LQTS-causing mutations in KCNQ1 (LQT1), KCNH2 (LQT2), SCN5A (LQT3), KCNE1 (LQT5), and KCNE2 (LQT6) was performed for 541 consecutive, unrelated patients (358 females, average age at diagnosis 24 +/- 16 years, average QTc 482 +/- 57 ms) referred to Mayo Clinic's Sudden Death Genomics Laboratory for LQTS genetic testing between August 1997 and July 2004. A comprehensive open reading frame and splice site analysis of the 60 protein-encoding exons was conducted using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing. RESULTS Overall, 211 putative pathogenic mutations in KCNQ1 (88), KCNH2 (89), SCN5A (32), KCNE1 (1), and KCNE2 (1) were found in 272 unrelated patients (50%). Among the genotype positive patients (N = 272), 243 had single pathogenic mutations (LQT1: n = 120 patients; LQT2: n = 93; LQT3: n = 26; LQT5: n = 3; LQT6: n = 1), and 29 patients (10% of genotype-positive patients and 5% overall) had two LQTS-causing mutations. The majority of mutations were missense mutations (154/210 [73%]), singletons (identified in only a single unrelated patient: 165/210 [79%]), and novel (125/211 [59%]). None of the mutations identified were seen in more than 1,500 reference alleles. Those patients harboring multiple mutations were younger at diagnosis (15 +/- 11 years vs 24 +/- 16 years, P = .003). CONCLUSIONS In this comprehensive cardiac channel gene screen of the largest cohort of consecutive, unrelated patients referred for LQTS genetic testing, half of the patients had an identifiable mutation. The majority of mutations continue to represent novel singletons that expand the published compendium of LQTS-causing mutations by 35%. These observations should facilitate diagnostic interpretation of the clinical genetic test for LQTS.
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Affiliation(s)
- David J Tester
- Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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