1
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Kihlgren M, Almqvist C, Amankhani F, Jonasson L, Norman C, Perez M, Ebrahimi A, Gottfridsson C. The U-wave: A remaining enigma of the electrocardiogram. J Electrocardiol 2023; 79:13-20. [PMID: 36907158 DOI: 10.1016/j.jelectrocard.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 02/24/2023] [Accepted: 03/01/2023] [Indexed: 03/07/2023]
Abstract
The U-wave's electrophysiological origin remains unknown and is subject to debate. It is rarely used for diagnosis in clinical practice. The aim of this study was to review new information regarding the U-wave. Further to present the proposed theories behind the U-wave's origin along with potential pathophysiologic and prognostic implications related to its presence, polarity and morphology. METHOD Literature searches were conducted to retrieve publications related to the electrocardiogram U-wave in the literature database Embase. RESULTS The review of the literature revealed the following major theories that will be discussed; late depolarisation, delayed or prolonged repolarisation, electro-mechanical stretch and IK1 dependent intrinsic potential differences in the terminal part of the action potential. Various pathologic conditions were found to correlate with the presence and properties of the U-wave, such as its amplitude and polarity. Abnormal U-waves can, for example, be observed in coronary artery disease with ongoing myocardial ischemia or infarction, ventricular hypertrophy, congenital heart disease, primary cardiomyopathy and valvular defects. Negative U-waves are highly specific for the presence of heart diseases. Concordantly negative T- and U-waves are especially associated with cardiac disease. Patients with negative U-waves tend to have higher blood pressure and history of hypertension, higher heart rate, cardiac disease and left ventricular hypertrophy compared to subjects with normal U-waves. Negative U-waves have been found to be associated with increased risk of all-cause mortality, cardiac death and cardiac hospitalisation in men. CONCLUSIONS The origin of the U-wave is still not established. U-wave diagnostics may reveal cardiac disorders and the cardiovascular prognosis. Including the U-wave characteristics in the clinical ECG assessment may be useful.
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Affiliation(s)
- Moa Kihlgren
- Cardiovascular Safety Center of Excellence and Safety Knowledge Groups, Global Patient Safety, Oncology R&D, AstraZeneca Gothenburg, Sweden.
| | - Christina Almqvist
- Cardiovascular Safety Center of Excellence and Safety Knowledge Groups, Global Patient Safety, Oncology R&D, AstraZeneca Gothenburg, Sweden.
| | - Fereydoun Amankhani
- Cardiovascular Safety Center of Excellence and Safety Knowledge Groups, Global Patient Safety, Oncology R&D, AstraZeneca Gothenburg, Sweden.
| | - Linda Jonasson
- Cardiovascular Safety Center of Excellence and Safety Knowledge Groups, Global Patient Safety, Oncology R&D, AstraZeneca Gothenburg, Sweden.
| | - Cecilia Norman
- Cardiovascular Safety Center of Excellence and Safety Knowledge Groups, Global Patient Safety, Oncology R&D, AstraZeneca Gothenburg, Sweden.
| | - Marcos Perez
- Cardiovascular Safety Center of Excellence and Safety Knowledge Groups, Global Patient Safety, Oncology R&D, AstraZeneca Gothenburg, Sweden.
| | - Ahmad Ebrahimi
- Cardiovascular Safety Center of Excellence and Safety Knowledge Groups, Global Patient Safety, Oncology R&D, AstraZeneca Gothenburg, Sweden.
| | - Christer Gottfridsson
- Cardiovascular Safety Center of Excellence and Safety Knowledge Groups, Global Patient Safety, Oncology R&D, AstraZeneca Gothenburg, Sweden.
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2
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Klein MG, Krantz MJ, Fatima N, Watters A, Colon-Sanchez D, Geiger RM, Goldstein RE, Solhjoo S, Mehler PS, Flagg TP, Haigney MC. Methadone Blockade of Cardiac Inward Rectifier K + Current Augments Membrane Instability and Amplifies U Waves on Surface ECGs: A Translational Study. J Am Heart Assoc 2022; 11:e023482. [PMID: 35658478 PMCID: PMC9238736 DOI: 10.1161/jaha.121.023482] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Background Methadone is associated with a disproportionate risk of sudden death and ventricular tachyarrhythmia despite only modest inhibition of delayed rectifier K+ current (IKr), the principal mechanism of drug-associated arrhythmia. Congenital defects of inward rectifier K+ current (IK1) have been linked to increased U-wave amplitude on ECG and fatal arrhythmia. We hypothesized that methadone may also be a potent inhibitor of IK1, contributing to delayed repolarization and manifesting on surface ECGs as augmented U-wave integrals. Methods and Results Using a whole-cell voltage clamp, methadone inhibited both recombinant and native IK1 with a half-maximal inhibitory concentration IC50) of 1.5 μmol/L, similar to that observed for IKr block (half-maximal inhibitory concentration of 2.9 μmol/L). Methadone modestly increased the action potential duration at 90% repolarization and slowed terminal repolarization at low concentrations. At higher concentrations, action potential duration at 90% repolarization lengthening was abolished, but its effect on terminal repolarization rose steadily and correlated with increased fluctuations of diastolic membrane potential. In parallel, patient ECGs were analyzed before and after methadone initiation, with 68% of patients having a markedly increased U-wave integral compared with premethadone (lead V3; mean +38%±15%, P=0.016), along with increased QT and TPeak to TEnd intervals, likely reflective of IKr block. Conclusions Methadone is a potent IK1 inhibitor that causes augmentation of U waves on surface ECG. We propose that increased membrane instability resulting from IK1 block may better explain methadone's arrhythmia risk beyond IKr inhibition alone. Drug-induced augmentation of U waves may represent evidence of blockade of multiple repolarizing ion channels, and evaluation of the effect of that agent on IK1 may be warranted.
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Affiliation(s)
- Michael G Klein
- Cardiology Division Department of Medicine Uniformed Services University Bethesda MD
| | - Mori J Krantz
- Denver Health Medical Center Cardiology Division Denver CO.,Department of Medicine University of Colorado School of Medicine Aurora CO.,Chief Science Advisor Cardiac Safety and Cardiovascular Imaging, Clario Inc. Philadelphia PA
| | - Naheed Fatima
- Department of Anatomy, Physiology & Genetics Uniformed Services University Bethesda MD
| | - Ashlie Watters
- ACUTE at Denver Health Denver CO.,Department of Medicine University of Colorado School of Medicine Aurora CO
| | - Dayan Colon-Sanchez
- Psychiatry Division Outpatient Behavioral Health Services, Denver Health, & University of Colorado School of Medicine Denver CO
| | - Robert M Geiger
- Department of Anatomy, Physiology & Genetics Uniformed Services University Bethesda MD
| | - Robert E Goldstein
- Cardiology Division Department of Medicine Uniformed Services University Bethesda MD
| | - Soroosh Solhjoo
- Cardiology Division Department of Medicine Uniformed Services University Bethesda MD.,Military Cardiovascular Outcomes Research (MiCOR) Bethesda MD
| | - Philip S Mehler
- ACUTE at Denver Health Denver CO.,Department of Medicine University of Colorado School of Medicine Aurora CO
| | - Thomas P Flagg
- Department of Anatomy, Physiology & Genetics Uniformed Services University Bethesda MD
| | - Mark C Haigney
- Cardiology Division Department of Medicine Uniformed Services University Bethesda MD.,Military Cardiovascular Outcomes Research (MiCOR) Bethesda MD
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3
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Cardiovascular Complications of Opioid Use: JACC State-of-the-Art Review. J Am Coll Cardiol 2021; 77:205-223. [PMID: 33446314 DOI: 10.1016/j.jacc.2020.11.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 12/29/2022]
Abstract
Opioids are the most potent of all analgesics. Although traditionally used solely for acute self-limited conditions and palliation of severe cancer-associated pain, a movement to promote subjective pain (scale, 0 to 10) to the status of a "fifth vital sign" bolstered widespread prescribing for chronic, noncancer pain. This, coupled with rising misuse, initiated a surge in unintentional deaths, increased drug-associated acute coronary syndrome, and endocarditis. In response, the American College of Cardiology issued a call to action for cardiovascular care teams. Opioid toxicity is primarily mediated via potent μ-receptor agonism resulting in ventilatory depression. However, both overdose and opioid withdrawal can trigger major adverse cardiovascular events resulting from hemodynamic, vascular, and proarrhythmic/electrophysiological consequences. Although natural opioid analogues are devoid of repolarization effects, synthetic agents may be proarrhythmic. This perspective explores cardiovascular consequences of opioids, the contributions of off-target electrophysiologic properties to mortality, and provides practical safety recommendations.
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4
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Wilde AAM, Amin AS, Postema PG. Diagnosis, management and therapeutic strategies for congenital long QT syndrome. Heart 2021; 108:332-338. [PMID: 34039680 PMCID: PMC8862104 DOI: 10.1136/heartjnl-2020-318259] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/12/2021] [Accepted: 05/03/2021] [Indexed: 11/18/2022] Open
Abstract
Congenital long QT syndrome (LQTS) is characterised by heart rate corrected QT interval prolongation and life-threatening arrhythmias, leading to syncope and sudden death. Variations in genes encoding for cardiac ion channels, accessory ion channel subunits or proteins modulating the function of the ion channel have been identified as disease-causing mutations in up to 75% of all LQTS cases. Based on the underlying genetic defect, LQTS has been subdivided into different subtypes. Growing insights into the genetic background and pathophysiology of LQTS has led to the identification of genotype–phenotype relationships for the most common genetic subtypes, the recognition of genetic and non-genetic modifiers of phenotype, optimisation of risk stratification algorithms and the discovery of gene-specific therapies in LQTS. Nevertheless, despite these great advancements in the LQTS field, large gaps in knowledge still exist. For example, up to 25% of LQTS cases still remain genotype elusive, which hampers proper identification of family members at risk, and it is still largely unknown what determines the large variability in disease severity, where even within one family an identical mutation causes malignant arrhythmias in some carriers, while in other carriers, the disease is clinically silent. In this review, we summarise the current evidence available on the diagnosis, clinical management and therapeutic strategies in LQTS. We also discuss new scientific developments and areas of research, which are expected to increase our understanding of the complex genetic architecture in genotype-negative patients, lead to improved risk stratification in asymptomatic mutation carriers and more targeted (gene-specific and even mutation-specific) therapies.
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Affiliation(s)
- Arthur A M Wilde
- Heart Centre, Department of Cardiology, Amsterdam Universitair Medische Centra, Amsterdam, The Netherlands
| | - Ahmad S Amin
- Heart Centre, Department of Cardiology, Amsterdam Universitair Medische Centra, Amsterdam, The Netherlands
| | - Pieter G Postema
- Heart Centre, Department of Cardiology, Amsterdam Universitair Medische Centra, Amsterdam, The Netherlands
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5
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Affiliation(s)
- Arja S Vink
- Department of Clinical and Experimental Cardiology Amsterdam University Medical CentersUniversity of AmsterdamHeart Center Amsterdam the Netherlands.,Department of Pediatric Cardiology Emma Children's HospitalAmsterdam University Medical CentersUniversity of Amsterdam Amsterdam the Netherlands
| | - Pieter G Postema
- Department of Clinical and Experimental Cardiology Amsterdam University Medical CentersUniversity of AmsterdamHeart Center Amsterdam the Netherlands
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6
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Horigome H, Ishikawa Y, Kokubun N, Yoshinaga M, Sumitomo N, Lin L, Kato Y, Tanabe-Kameda Y, Ohno S, Nagashima M, Horie M. Multivariate analysis of TU wave complex on electrocardiogram in Andersen-Tawil syndrome with KCNJ2 mutations. Ann Noninvasive Electrocardiol 2019; 25:e12721. [PMID: 31724784 PMCID: PMC7358888 DOI: 10.1111/anec.12721] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 09/26/2019] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The exact differences between the TU wave complex of ATS1 and that of healthy individuals remain to be investigated. We sought to characterize the TU wave complex of Andersen-Tawil syndrome type 1 (ATS1) using high frequency electrocardiogram (ECG) data. METHODS Electrocardiograms were recorded as time series data with a 2 kHz frequency ECG amplifier in 13 patients with ATS1 (positive for KCNJ2 mutation, ATS1 group) and age-matched healthy individuals (control group). Conventional ECG parameters were measured, and principal component analysis (PCA) and independent component analysis (ICA) were applied to the TU wave complex. RESULTS Time from T peak (Tp) to U peak (Up), time from bottom (B) to Up, and time from B to U end (BUe, U duration) (0.232 ± 0.018 vs. 0.165 ± 0.017, p < .0001), where B is the lowest point between T and U waves, were all longer in the ATS1 group than the control group. Multivariate logistic regression analysis revealed that BUe could completely differentiate the two groups. PCA ratios in the ATS1 group were significantly larger than the control group (26.5 ± 12.3 vs. 10.4 ± 6.2, p = .0005). ICA revealed 1 or 2 U-wave-specific independent components (ICs) that exclusively comprise the U wave in ATS1, whereas U waves in the control group were composed of some ICs that also comprised T waves. CONCLUSIONS U-wave-related temporal parameters, particularly BUe, and the existence of U-wave-specific ICs, extracted in the ICA, are useful for differentiation of U waves in ATS1 from those in healthy individuals.
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Affiliation(s)
- Hitoshi Horigome
- Department of Child Health, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | | | - Norito Kokubun
- Department of Neurology, Dokkyo Medical University, Tochigi, Japan
| | - Masao Yoshinaga
- Department of Pediatrics, National Hospital Organization Kagoshima Medical Center, Kagoshima, Japan
| | - Naokata Sumitomo
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center, Hidaka, Japan
| | - Lisheng Lin
- Department of Child Health, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Yoshiaki Kato
- Department of Child Health, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Yuri Tanabe-Kameda
- Department of Child Health, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Seiko Ohno
- Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center, Suita, Japan
| | | | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
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7
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The electrocardiogram of vertebrates: Evolutionary changes from ectothermy to endothermy. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 144:16-29. [DOI: 10.1016/j.pbiomolbio.2018.08.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 08/09/2018] [Accepted: 08/13/2018] [Indexed: 12/11/2022]
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8
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Sharma LD, Sunkaria RK. Detection and delineation of the enigmatic U-wave in an electrocardiogram. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s41870-019-00287-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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9
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Meta-analysis of T peak-T end and T peak-T end/QT ratio for risk stratification in congenital long QT syndrome. J Electrocardiol 2018; 51:396-401. [PMID: 29550106 DOI: 10.1016/j.jelectrocard.2018.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 02/13/2018] [Accepted: 03/06/2018] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND OBJECTIVES Congenital long QT syndrome (LQTS) predisposes affected individuals to ventricular tachycardia/fibrillation (VF/VF), potentially resulting in sudden cardiac death. The Tpeak-Tend interval and the Tpeak-Tend/QT ratio, electrocardiographic markers of dispersion of ventricular repolarization, were proposed for risk stratification but their predictive values in LQTS have been controversial. A systematic review and meta-analysis was conducted to examine the value of Tpeak-Tend intervals and Tpeak-Tend/QT ratios in predicting arrhythmic and mortality outcomes in congenital LQTS. METHOD PubMed and Embase databases were searched until 9th May 2017, identifying 199 studies. RESULTS Five studies on long QT syndrome were included in the final meta-analysis. Tpeak-Tend intervals were longer (mean difference [MD]: 13ms, standard error [SE]: 4ms, P=0.002; I2=34%) in congenital LQTS patients with adverse events [syncope, ventricular arrhythmias or sudden cardiac death] compared to LQTS patients without such events. By contrast, Tpeak-Tend/QT ratios were not significantly different between the two groups (MD: 0.02, SE: 0.02, P=0.26; I2=0%). CONCLUSION This meta-analysis showed that Tpeak-Tend interval is significant higher in individuals who are at elevated risk of adverse events in congenital LQTS, offering incremental value for risk stratification.
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10
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Ji Y, Takanari H, Qile M, Nalos L, Houtman MJC, Romunde FL, Heukers R, van Bergen En Henegouwen PMP, Vos MA, van der Heyden MAG. Class III antiarrhythmic drugs amiodarone and dronedarone impair K IR 2.1 backward trafficking. J Cell Mol Med 2017; 21:2514-2523. [PMID: 28425222 PMCID: PMC5618701 DOI: 10.1111/jcmm.13172] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 02/24/2017] [Indexed: 01/16/2023] Open
Abstract
Drug‐induced ion channel trafficking disturbance can cause cardiac arrhythmias. The subcellular level at which drugs interfere in trafficking pathways is largely unknown. KIR2.1 inward rectifier channels, largely responsible for the cardiac inward rectifier current (IK1), are degraded in lysosomes. Amiodarone and dronedarone are class III antiarrhythmics. Chronic use of amiodarone, and to a lesser extent dronedarone, causes serious adverse effects to several organs and tissue types, including the heart. Both drugs have been described to interfere in the late‐endosome/lysosome system. Here we defined the potential interference in KIR2.1 backward trafficking by amiodarone and dronedarone. Both drugs inhibited IK1 in isolated rabbit ventricular cardiomyocytes at supraclinical doses only. In HK‐KWGF cells, both drugs dose‐ and time‐dependently increased KIR2.1 expression (2.0 ± 0.2‐fold with amiodarone: 10 μM, 24 hrs; 2.3 ± 0.3‐fold with dronedarone: 5 μM, 24 hrs) and late‐endosomal/lysosomal KIR2.1 accumulation. Increased KIR2.1 expression level was also observed in the presence of Nav1.5 co‐expression. Augmented KIR2.1 protein levels and intracellular accumulation were also observed in COS‐7, END‐2, MES‐1 and EPI‐7 cells. Both drugs had no effect on Kv11.1 ion channel protein expression levels. Finally, amiodarone (73.3 ± 10.3% P < 0.05 at −120 mV, 5 μM) enhanced IKIR2.1 upon 24‐hrs treatment, whereas dronedarone tended to increase IKIR2.1 and it did not reach significance (43.8 ± 5.5%, P = 0.26 at −120 mV; 2 μM). We conclude that chronic amiodarone, and potentially also dronedarone, treatment can result in enhanced IK1 by inhibiting KIR2.1 degradation.
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Affiliation(s)
- Yuan Ji
- Division of Heart & Lungs, Department of Medical Physiology, UMCU, Utrecht, The Netherlands
| | - Hiroki Takanari
- Division of Heart & Lungs, Department of Medical Physiology, UMCU, Utrecht, The Netherlands
| | - Muge Qile
- Division of Heart & Lungs, Department of Medical Physiology, UMCU, Utrecht, The Netherlands
| | - Lukas Nalos
- Department of Physiology, Faculty of Medicine in Pilsen, Charles University in Prague, Pilsen, Czech Republic
| | - Marien J C Houtman
- Division of Heart & Lungs, Department of Medical Physiology, UMCU, Utrecht, The Netherlands
| | - Fee L Romunde
- Division of Heart & Lungs, Department of Medical Physiology, UMCU, Utrecht, The Netherlands
| | - Raimond Heukers
- Cell Biology, Department of Biology, Science Faculty, Utrecht University, Utrecht, The Netherlands
| | | | - Marc A Vos
- Division of Heart & Lungs, Department of Medical Physiology, UMCU, Utrecht, The Netherlands
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11
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Bohnen MS, Peng G, Robey SH, Terrenoire C, Iyer V, Sampson KJ, Kass RS. Molecular Pathophysiology of Congenital Long QT Syndrome. Physiol Rev 2017; 97:89-134. [PMID: 27807201 PMCID: PMC5539372 DOI: 10.1152/physrev.00008.2016] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ion channels represent the molecular entities that give rise to the cardiac action potential, the fundamental cellular electrical event in the heart. The concerted function of these channels leads to normal cyclical excitation and resultant contraction of cardiac muscle. Research into cardiac ion channel regulation and mutations that underlie disease pathogenesis has greatly enhanced our knowledge of the causes and clinical management of cardiac arrhythmia. Here we review the molecular determinants, pathogenesis, and pharmacology of congenital Long QT Syndrome. We examine mechanisms of dysfunction associated with three critical cardiac currents that comprise the majority of congenital Long QT Syndrome cases: 1) IKs, the slow delayed rectifier current; 2) IKr, the rapid delayed rectifier current; and 3) INa, the voltage-dependent sodium current. Less common subtypes of congenital Long QT Syndrome affect other cardiac ionic currents that contribute to the dynamic nature of cardiac electrophysiology. Through the study of mutations that cause congenital Long QT Syndrome, the scientific community has advanced understanding of ion channel structure-function relationships, physiology, and pharmacological response to clinically employed and experimental pharmacological agents. Our understanding of congenital Long QT Syndrome continues to evolve rapidly and with great benefits: genotype-driven clinical management of the disease has improved patient care as precision medicine becomes even more a reality.
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Affiliation(s)
- M S Bohnen
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - G Peng
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - S H Robey
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - C Terrenoire
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - V Iyer
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - K J Sampson
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - R S Kass
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
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12
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Randomized, double-blind, placebo-controlled clinical trial of a two-day regimen of dihydroartemisinin-piperaquine for malaria prevention halted for concern over prolonged corrected QT interval. Antimicrob Agents Chemother 2014; 58:6056-67. [PMID: 25092702 DOI: 10.1128/aac.02667-14] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dihydroartemisinin-piperaquine, the current first-line drug for uncomplicated malaria caused by Plasmodium falciparum and Plasmodium vivax in Cambodia, was previously shown to be of benefit as malaria chemoprophylaxis when administered as a monthly 3-day regimen. We sought to evaluate the protective efficacy of a compressed monthly 2-day treatment course in the Royal Cambodian Armed Forces. The safety and efficacy of a monthly 2-day dosing regimen of dihydroartemisinin-piperaquine were evaluated in a two-arm, randomized, double-blind, placebo-controlled cohort study with 2:1 treatment allocation. Healthy military volunteers in areas along the Thai-Cambodian border where there is a high risk of malaria were administered two consecutive daily doses of 180 mg dihydroartemisinin and 1,440 mg piperaquine within 30 min to 3 h of a meal once per month for a planned 4-month period with periodic electrocardiographic and pharmacokinetic assessment. The study was halted after only 6 weeks (69 of 231 projected volunteers enrolled) when four volunteers met a prespecified cardiac safety endpoint of QTcF (Fridericia's formula for correct QT interval) prolongation of >500 ms. The pharmacodynamic effect on the surface electrocardiogram (ECG) peaked approximately 4 h after piperaquine dosing and lasted 4 to 8 h. Unblinded review by the data safety monitoring board revealed mean QTcF prolongation of 46 ms over placebo at the maximum concentration of drug in serum (Cmax) on day 2. Given that dihydroartemisinin-piperaquine is one of the few remaining effective antimalarial agents in Cambodia, compressed 2-day treatment courses of dihydroartemisinin-piperaquine are best avoided until the clinical significance of these findings are more thoroughly evaluated. Because ECG monitoring is often unavailable in areas where malaria is endemic, repolarization risk could be mitigated by using conventional 3-day regimens, fasting, and avoidance of repeated dosing or coadministration with other QT-prolonging medications. (This study has been registered at ClinicalTrials.gov under registration no. NCT01624337.).
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13
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Postema PG, Wilde AAM. The measurement of the QT interval. Curr Cardiol Rev 2014; 10:287-94. [PMID: 24827793 PMCID: PMC4040880 DOI: 10.2174/1573403x10666140514103612] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 06/10/2013] [Accepted: 01/28/2014] [Indexed: 12/14/2022] Open
Abstract
The evaluation of every electrocardiogram should also include an effort to interpret the QT interval to assess the risk of malignant arrhythmias and sudden death associated with an aberrant QT interval. The QT interval is measured from the beginning of the QRS complex to the end of the T-wave, and should be corrected for heart rate to enable comparison with reference values. However, the correct determination of the QT interval, and its value, appears to be a daunting task. Although computerized analysis and interpretation of the QT interval are widely available, these might well over- or underestimate the QT interval and may thus either result in unnecessary treatment or preclude appropriate measures to be taken. This is particularly evident with difficult T-wave morphologies and technically suboptimal ECGs. Similarly, also accurate manual assessment of the QT interval appears to be difficult for many physicians worldwide. In this review we delineate the history of the measurement of the QT interval, its underlying pathophysiological mechanisms and the current standards of the measurement of the QT interval, we provide a glimpse into the future and we discuss several issues troubling accurate measurement of the QT interval. These issues include the lead choice, U-waves, determination of the end of the T-wave, different heart rate correction formulas, arrhythmias and the definition of normal and aberrant QT intervals. Furthermore, we provide recommendations that may serve as guidance to address these complexities and which support accurate assessment of the QT interval and its interpretation.
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Affiliation(s)
| | - Arthur A M Wilde
- Department of Cardiology, Academic Medical Center, P.O. box 22660, 1100 DD Amsterdam, The Netherlands.
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14
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Bhoelan BS, Stevering CH, van der Boog ATJ, van der Heyden MAG. Barium toxicity and the role of the potassium inward rectifier current. Clin Toxicol (Phila) 2014; 52:584-93. [DOI: 10.3109/15563650.2014.923903] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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15
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Fereniec M, Stix G, Kania M, Mroczka T, Maniewski R. An analysis of the U-wave and its relation to the T-wave in body surface potential maps for healthy subjects and MI patients. Ann Noninvasive Electrocardiol 2014; 19:145-56. [PMID: 24191849 PMCID: PMC6932608 DOI: 10.1111/anec.12110] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND The aim of this study was to analyze the U-wave morphology and its relation to the T-wave in one group of healthy subjects and in two groups of myocardial infarction (MI) patients-with and without ventricular tachycardia (VT) episodes. The context of the U-wave origin was also discussed and the U-wave as a potential marker of VT was investigated. METHODS The study was carried out on three groups of subjects: 20 healthy subjects, 14 MI patients not at risk of VT, and 22 MI patients at risk of VT. The morphology of the repolarization phase was examined in the high-resolution body surface potential maps recorded from 64 surface ECG leads. The temporal and spatial distributions of several ECG parameters were studied. RESULTS The U-wave was present in almost all the studied subjects. The spatial heterogeneity and smooth change in both the T- and U-wave shapes on the entire torso were observed in all the studied groups. The statistical significance of discrimination between the MI patients without VT and MI patients with VT was observed for QRS interval, QT interval, U-wave integral, and normalized U-wave integral. CONCLUSIONS High-resolution measurement of body surface potentials and an advanced data analysis allow for a detailed description of U-wave morphology and its relation to the T-wave. This might be of value in discriminating intracardiac repolarization effects, mechano-electrical feedback, and arrhythmia risk stratification.
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Affiliation(s)
- Małgorzata Fereniec
- Department of Biophysical Measurements and ImagingNalecz Institute of Biocybernetics and Biomedical EngineeringPolish Academy of SciencesWarsawPoland
| | - Günter Stix
- Department of CardiologyMedical University of ViennaGeneral Hospital of ViennaViennaAustria
| | - Michał Kania
- Department of Biophysical Measurements and ImagingNalecz Institute of Biocybernetics and Biomedical EngineeringPolish Academy of SciencesWarsawPoland
| | - Tomasz Mroczka
- Department of Internal Medicine and CardiologyGeriatric Center WienerwaldViennaAustria
| | - Roman Maniewski
- Department of Biophysical Measurements and ImagingNalecz Institute of Biocybernetics and Biomedical EngineeringPolish Academy of SciencesWarsawPoland
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Wilde AAM. Andersen-Tawil syndrome, scarier for the doctor than for the patient? Who, when, and how to treat. Europace 2013; 15:1690-2. [PMID: 24128811 DOI: 10.1093/europace/eut326] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Arthur A M Wilde
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam 1100 DE, The Netherlands
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Delannoy E, Sacher F, Maury P, Mabo P, Mansourati J, Magnin I, Camous JP, Tournant G, Rendu E, Kyndt F, Haïssaguerre M, Bézieau S, Guyomarch B, Le Marec H, Fressart V, Denjoy I, Probst V. Cardiac characteristics and long-term outcome in Andersen-Tawil syndrome patients related to KCNJ2 mutation. Europace 2013; 15:1805-11. [PMID: 23867365 DOI: 10.1093/europace/eut160] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Andersen-Tawil syndrome (ATS) is an uncommon form of channelopathy linked to mutations in the KCNJ2 gene. Currently, little is known about the long-term arrhythmic prognosis of this disease. METHODS AND RESULTS We conducted a retrospective multicentre study in nine French hospitals. Patients were recruited only if they were KCNJ2 mutation carriers. Thirty-six patients (female n = 22, 61%) from 20 unrelated kindred were included with a mean follow-up of 9.5 ± 8.2 years. We found 12 distinct KCNJ2 mutations in the 20 probands. Three of them were novel. Thirteen patients (36%) experienced syncope and one patient was resuscitated from cardiac arrest before diagnosis. The mean QTc interval was 439 ± 57 ms and QUc was 642 ± 64 ms. All patients had normal ejection fraction. Holter recordings in 33 patients found 11 272 premature ventricular complexes (PVCs) per day on average, 25 patients had episodes of bigeminy, and 25 patients had polymorphic PVCs. Twenty-three patients (70%) had non-sustained polymorphic ventricular tachycardia (VT), and six sustained polymorphic VT. Only one patient presented with torsades de pointes. Patients were treated with beta-blocker (n = 20), beta-blocker and amiodarone (n = 2), beta-blocker and flecainide (n = 6), or acetazolamide (n = 6). Radiofrequency ablation was attempted in five patients without clinical success. An implantable cardiac defibrillator was implanted in three patients. During follow-up, none of the patients died, four patients experienced syncope under treatment, and one patient had non-fatal cardiac arrest. CONCLUSION Despite a severe clinical presentation with a very high rate of ventricular arrhythmias, the arrhythmic prognosis of the ATS patients is relatively good under treatment.
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Affiliation(s)
- Eric Delannoy
- L'Institut du Thorax, Department of Cardiology, Bd Monod, Nantes University Hospital, 44093, Nantes, France
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Affiliation(s)
- Pieter G Postema
- Department of cardiology, Heart Center, Academic Medical Center, Amsterdam, The Netherlands.
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Stern S. The Year of 2009 in Electrocardiology. Ann Noninvasive Electrocardiol 2010; 15:378-83. [DOI: 10.1111/j.1542-474x.2010.00394.x] [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: 11/28/2022] Open
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Anumonwo JMB, Lopatin AN. Cardiac strong inward rectifier potassium channels. J Mol Cell Cardiol 2009; 48:45-54. [PMID: 19703462 DOI: 10.1016/j.yjmcc.2009.08.013] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 08/13/2009] [Accepted: 08/18/2009] [Indexed: 10/20/2022]
Abstract
Cardiac I(K1) and I(KACh) are the major potassium currents displaying classical strong inward rectification, a unique property that is critical for their roles in cardiac excitability. In the last 15 years, research on I(K1) and I(KACh) has been propelled by the cloning of the underlying inwardly rectifying potassium (Kir) channels, the discovery of the molecular mechanism of strong rectification and the linking of a number of disorders of cardiac excitability to defects in genes encoding Kir channels. Disease-causing mutations in Kir genes have been shown experimentally to affect one or more of the following channel properties: structure, assembly, trafficking, and regulation, with the ultimate effect of a gain- or a loss-of-function of the channel. It is now established that I(K1) and I(KACh) channels are heterotetramers of Kir2 and Kir3 subunits, respectively. Each homomeric Kir channel has distinct biophysical and regulatory properties, and individual Kir subunits often display different patterns of regional, cellular, and membrane distribution. These differences are thought to underlie important variations in the physiological properties of I(K1) and I(KACh). It has become increasingly clear that the contribution of I(K1) and I(KACh) channels to cardiac electrical activity goes beyond their long recognized role in the stabilization of resting membrane potential and shaping the late phase of action potential repolarization in individual myocytes but extends to being critical elements determining the overall electrical stability of the heart.
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Affiliation(s)
- Justus M B Anumonwo
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-5622, USA
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Amin AS, Tan HL, Wilde AAM. Cardiac ion channels in health and disease. Heart Rhythm 2009; 7:117-26. [PMID: 19875343 DOI: 10.1016/j.hrthm.2009.08.005] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Accepted: 08/01/2009] [Indexed: 01/08/2023]
Abstract
Cardiac electrical activity depends on the coordinated propagation of excitatory stimuli through the heart and, as a consequence, the generation of action potentials in individual cardiomyocytes. Action potential formation results from the opening and closing (gating) of ion channels that are expressed within the sarcolemma of cardiomyocytes. Ion channels possess distinct genetic, molecular, pharmacologic, and gating properties and exhibit dissimilar expression levels within different cardiac regions. By gating, ion channels permit ion currents across the sarcolemma, thereby creating the different phases of the action potential (e.g., resting phase, depolarization, repolarization). The importance of ion channels in maintaining normal heart rhythm is reflected by the increased incidence of arrhythmias in inherited diseases that are linked to mutations in genes encoding ion channels or their accessory proteins and in acquired diseases that are associated with changes in ion channel expression levels or gating properties. This review discusses ion channels that contribute to action potential formation in healthy hearts and their role in inherited and acquired diseases.
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Affiliation(s)
- Ahmad S Amin
- Heart Failure Research Center, University of Amsterdam, Amsterdam, The Netherlands
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