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Harvey A, Curnier D, Dodin P, Jacquemet V, Caru M. The Effects of Cycle Ergometer Versus Treadmill Exercise Stress Testing on QTc Interval Prolongation in Patients With Long QT Syndrome: A Systematic Review and Meta-analysis. Clin J Sport Med 2024:00042752-990000000-00218. [PMID: 39012267 DOI: 10.1097/jsm.0000000000001256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 01/16/2024] [Indexed: 07/17/2024]
Abstract
OBJECTIVE The safest and most effective exercise stress tests (EST) modalities for long QT syndrome (LQTS) are currently unknown. The main objective was to explore the effects of EST on the corrected QT interval (QTc) in patients with LQTS, and to compare the effects of different EST modalities (cycle ergometer vs treadmill). DATA SOURCES Systematic searches were performed in September 2022 in accordance with the PRISMA statement through PubMed, Medline, EBM Reviews, Embase, and Web of Science. MAIN RESULTS A total of 1728 patients with LQTS, whether congenital or acquired, without any age restrictions (pediatric age ≤18 years and adult age >19 years), and 2437 control subjects were included in the 49 studies. The QT interval data were available for 15 studies. Our analyses showed that the QT interval prolonged in a similar manner using either a cycle ergometer or a treadmill (standardized mean difference [SMD] = 1.89 [95% CI, 1.07-2.71] vs SMD = 1.46 [95% CI, 0.78-2.14], respectively). Therefore, it seems that either modality may be used to evaluate patients with LQTS. CONCLUSIONS The methodology for the measurement of the QT interval was very heterogeneous between studies, which inevitably influenced the quality of the analyses. Hence, researchers should proceed with caution when exploring and interpreting data in the field of exercise and LQTS.
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Affiliation(s)
- Audrey Harvey
- Laboratory of Pathophysiology of EXercise (LPEX), School of Kinesiology and Physical Activity Sciences, Faculty of Medicine, University of Montreal, Montreal, Canada
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Daniel Curnier
- Laboratory of Pathophysiology of EXercise (LPEX), School of Kinesiology and Physical Activity Sciences, Faculty of Medicine, University of Montreal, Montreal, Canada
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Philippe Dodin
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Vincent Jacquemet
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, Canada; and
| | - Maxime Caru
- Department of Pediatrics and Department of Public Health Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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Cui S, Hayashi K, Kobayashi I, Hosomichi K, Nomura A, Teramoto R, Usuda K, Okada H, Deng Y, Kobayashi-Sun J, Nishikawa T, Furusho H, Saito T, Hirase H, Ohta K, Fujimoto M, Horita Y, Kusayama T, Tsuda T, Tada H, Kato T, Usui S, Sakata K, Fujino N, Tajima A, Yamagishi M, Takamura M. The utility of zebrafish cardiac arrhythmia model to predict the pathogenicity of KCNQ1 variants. J Mol Cell Cardiol 2023; 177:50-61. [PMID: 36898499 DOI: 10.1016/j.yjmcc.2023.03.001] [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: 11/04/2022] [Revised: 03/01/2023] [Accepted: 03/02/2023] [Indexed: 03/11/2023]
Abstract
Genetic testing for inherited arrhythmias and discriminating pathogenic or benign variants from variants of unknown significance (VUS) is essential for gene-based medicine. KCNQ1 is a causative gene of type 1 long QT syndrome (LQTS), and approximately 30% of the variants found in type 1 LQTS are classified as VUS. We studied the role of zebrafish cardiac arrhythmia model in determining the clinical significance of KCNQ1 variants. We generated homozygous kcnq1 deletion zebrafish (kcnq1del/del) using the CRISPR/Cas9 and expressed human Kv7.1/MinK channels in kcnq1del/del embryos. We dissected the hearts from the thorax at 48 h post-fertilization and measured the transmembrane potential of the ventricle in the zebrafish heart. Action potential duration was calculated as the time interval between peak maximum upstroke velocity and 90% repolarization (APD90). The APD90 of kcnq1del/del embryos was 280 ± 47 ms, which was significantly shortened by injecting KCNQ1 wild-type (WT) cRNA and KCNE1 cRNA (168 ± 26 ms, P < 0.01 vs. kcnq1del/del). A study of two pathogenic variants (S277L and T587M) and one VUS (R451Q) associated with clinically definite LQTS showed that the APD90 of kcnq1del/del embryos with these mutant Kv7.1/MinK channels was significantly longer than that of Kv7.1 WT/MinK channels. Given the functional results of the zebrafish model, R451Q could be reevaluated physiologically from VUS to likely pathogenic. In conclusion, functional analysis using in vivo zebrafish cardiac arrhythmia model can be useful for determining the pathogenicity of loss-of-function variants in patients with LQTS.
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Affiliation(s)
- Shihe Cui
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Kenshi Hayashi
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan; School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
| | - Isao Kobayashi
- Faculty of Biological Science and Technology, Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan
| | - Kazuyoshi Hosomichi
- Laboratory of Computational Genomics, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Akihiro Nomura
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Ryota Teramoto
- Laboratory for Comprehensive Genomic Analysis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Keisuke Usuda
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hirofumi Okada
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Yaowen Deng
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Jingjing Kobayashi-Sun
- Faculty of Biological Science and Technology, Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan; Department of Clinical Engineering, Faculty of Health Sciences, Komatsu University, Komatsu, Japan
| | - Tetsuo Nishikawa
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hiroshi Furusho
- Department of Cardiology, Ishikawa Prefectural Central Hospital, Kanazawa, Japan
| | - Takekatsu Saito
- Department of Pediatrics, Minamigaoka Hospital, Kanazawa, Japan
| | - Hiroaki Hirase
- Department of Cardiology, Takaoka Minami Heart Center, Takaoka, Japan
| | - Kunio Ohta
- Department of Pediatrics, School of Medicine, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan; Medical Education Research Center, Graduate School of Medical Sciences, Kanazawa University, Japan
| | - Manabu Fujimoto
- Department of Cardiology, Kouseiren Takaoka Hospital, Takaoka, Japan
| | - Yuki Horita
- Department of Cardiology, Kanazawa Cardiovascular Hospital, Kanazawa, Japan
| | - Takashi Kusayama
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Toyonobu Tsuda
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hayato Tada
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Takeshi Kato
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Soichiro Usui
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Kenji Sakata
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Noboru Fujino
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan; School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Atsushi Tajima
- Department of Bioinformatics and Genomics, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, Kanazawa, Japan
| | | | - Masayuki Takamura
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
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Harvey A, Curnier D, Dodin P, Abadir S, Jacquemet V, Caru M. OUP accepted manuscript. Eur J Prev Cardiol 2022; 29:1633-1677. [PMID: 35537006 DOI: 10.1093/eurjpc/zwac081] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/15/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022]
Abstract
Current exercise recommendations make it difficult for long QT syndrome (LQTS) patients to adopt a physically active and/or athletic lifestyle. The purpose of this review is to summarize the current evidence, identify knowledge gaps, and discuss research perspectives in the field of exercise and LQTS. The first aim is to document the influence of exercise training, exercise stress, and postural change interventions on ventricular repolarization in LQTS patients, while the second aim is to describe electrophysiological measurements used to study the above. Studies examining the effects of exercise on congenital or acquired LQTS in human subjects of all ages were included. Systematic searches were performed on 1 October 2021, through PubMed (NLM), Ovid Medline, Ovid All EBM Reviews, Ovid Embase, and ISI Web of Science, and limited to articles written in English or French. A total of 1986 LQTS patients and 2560 controls were included in the 49 studies. Studies were mainly case-control studies (n = 41) and examined exercise stress and/or postural change interventions (n = 48). One study used a 3-month exercise training program. Results suggest that LQTS patients have subtype-specific repolarization responses to sympathetic stress. Measurement methods and quality were found to be very heterogeneous, which makes inter-study comparisons difficult. In the absence of randomized controlled trials, the current recommendations may have long-term risks for LQTS patients who are discouraged from performing physical activity, rendering its associated health benefits out of range. Future research should focus on discovering the most appropriate levels of exercise training that promote ventricular repolarization normalization in LQTS.
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Affiliation(s)
- Audrey Harvey
- Laboratory of Pathophysiology of EXercise (LPEX), School of Kinesiology and Physical Activity Sciences, Faculty of Medicine, University of Montreal, Montreal, Canada
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Daniel Curnier
- Laboratory of Pathophysiology of EXercise (LPEX), School of Kinesiology and Physical Activity Sciences, Faculty of Medicine, University of Montreal, Montreal, Canada
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Philippe Dodin
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Sylvia Abadir
- Department of Pediatric Cardiology, Sainte-Justine University Health Center, Montreal, Canada
| | - Vincent Jacquemet
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, Canada
| | - Maxime Caru
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
- Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA
- Department of Public Health Sciences, Pennsylvania State University College of Medicine, Hershey, PA, USA
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Maury P, Delasnerie H, Beneyto M, Rollin A. Autonomic cardiac innervation: impact on the evolution of arrhythmias in inherited cardiac arrhythmia syndromes. Herzschrittmacherther Elektrophysiol 2021; 32:308-314. [PMID: 34185133 DOI: 10.1007/s00399-021-00774-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 05/17/2021] [Indexed: 11/28/2022]
Abstract
The autonomic nervous system (ANS) is an essential component of arrhythmogenicity, especially in the absence of structural heart disease and channelopathy. In this article, the authors review the role and characteristics of ANS in various channelopathies. Some of these, such as most long QT syndromes and catecholaminergic polymorphic ventricular tachycardia, are highly dependent on sympathetic activation, while parasympathetic tone is an important factor for arrhythmias in other channelopathies such as Brugada syndrome or early repolarisation syndrome. Recent advances highlighting the subtle role of ANS in channelopathies are presented here, demonstrating that all is far from being so simple and straightforward and revealing some paradoxical behaviours of channelopathies in relation to discrete ANS imbalance.
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Affiliation(s)
- Philippe Maury
- Department of Cardiology, University Hospital Rangueil, Toulouse, France. .,I2MC, INSERM UMR 1297, Toulouse, France.
| | - Hubert Delasnerie
- Department of Cardiology, University Hospital Rangueil, Toulouse, France
| | - Maxime Beneyto
- Department of Cardiology, University Hospital Rangueil, Toulouse, France
| | - Anne Rollin
- Department of Cardiology, University Hospital Rangueil, Toulouse, France
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Abstract
OBJECTIVE Menopausal hot flushes are associated with elevated activity of the sympathetic nervous system and may be related to increased risk for cardiovascular events. Sympathetic activation may trigger severe arrhythmias by modulating cardiac repolarization. The aim of this study was to evaluate the impact of hot flushes on cardiac repolarization in postmenopausal women with and without hot flushes. METHODS We assessed 150 recently postmenopausal healthy women-72 with hot flushes and 78 without hot flushes. They underwent 24-hour electrocardiographic recording, comprising a total of over 10,000,000 QT-interval measurements. The cardiac repolarization was assessed by measuring QT-intervals, heat rate dependence of QT-end intervals, and T-waves. RESULTS The maximal QT-end interval was shorter in women with hot flushes compared with those without hot flushes (481 ± 64 ms vs 493 ± 50 ms; P = 0.046). There were no differences between the rate dependence of QT-end intervals and T-wave measures between the groups. During the night-time hot flush period, we detected a steeper rate-dependence of QT-end intervals and a longer maximal T-peak-T-end interval (117 ± 54 ms vs 111 ± 56 ms; P < 0.001) compared with the control period. CONCLUSIONS Women with hot flushes did not have clinically significant differences in ambulatory cardiac repolarization measurements compared with asymptomatic women. However, a sudden sympathetic surge occurring during the night-time hot flush may have direct effects on cardiac repolarization.
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Zaza A, Ronchi C, Malfatto G. Arrhythmias and Heart Rate: Mechanisms and Significance of a Relationship. Arrhythm Electrophysiol Rev 2018; 7:232-237. [PMID: 30588310 DOI: 10.15420/aer.2018.12.3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 05/17/2018] [Indexed: 11/04/2022] Open
Abstract
The occurrence of arrhythmia is often related to basic heart rate. Prognostic significance is associated with such a relationship; furthermore, heart rate modulation may result as an ancillary effect of therapy, or be considered as a therapeutic tool. This review discusses the cellular mechanisms underlying arrhythmia occurrence during tachycardia or bradycardia, considering rate changes per se or as a mirror of autonomic modulation. Besides the influence of steady-state heart rate, dynamic aspects of changes in rate and autonomic balance are considered. The discussion leads to the conclusion that the prognostic significance of arrhythmia relationship with heart rate, and the consequence of heart rate on arrhythmogenesis, may vary according to the substrate present in the specific case and should be considered accordingly.
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Affiliation(s)
- Antonio Zaza
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi Milano-Bicocca Milan, Italy.,CARIM, Maastricht University Maastricht, the Netherlands
| | - Carlotta Ronchi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi Milano-Bicocca Milan, Italy
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Nicolson WB, McCann GP, Brown PD, Sandilands AJ, Stafford PJ, Schlindwein FS, Samani NJ, Ng GA. A novel surface electrocardiogram-based marker of ventricular arrhythmia risk in patients with ischemic cardiomyopathy. J Am Heart Assoc 2012; 1:e001552. [PMID: 23130163 PMCID: PMC3487358 DOI: 10.1161/jaha.112.001552] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 05/02/2012] [Indexed: 11/24/2022]
Abstract
Background Better sudden cardiac death risk markers are needed in ischemic cardiomyopathy (ICM). Increased heterogeneity of electrical restitution is an important mechanism underlying the risk of ventricular arrhythmia (VA). Our aim was to develop and test a novel quantitative surface electrocardiogram–based measure of VA risk in patients with ICM: the Regional Restitution Instability Index (R2I2). Methods and Results R2I2, the mean of the standard deviation of residuals from the mean gradient for each ECG lead at a range of diastolic intervals, was measured retrospectively from high-resolution 12-lead ECGs recorded during an electrophysiology study. Patient groups were as follows: Study group, 26 patients with ICM being assessed for implantable defibrillator; Control group, 29 patients with supraventricular tachycardia undergoing electrophysiology study; and Replication group, 40 further patients with ICM. R2I2 was significantly higher in the Study patients than in Controls (mean ± standard error of the mean: 1.09±0.06 versus 0.63±0.04, P<0.001). Over a median follow-up period of 23 months, 6 of 26 Study group patients had VA or death. R2I2 predicted VA or death independently of demographic factors, electrophysiology study result, left ventricular ejection fraction, or QRS duration (Cox model, P=0.029). R2I2 correlated with peri-infarct zone as assessed by cardiac magnetic resonance imaging (r=0.51, P=0.024). The findings were replicated in the Replication group: R2I2 was significantly higher in 11 of 40 Replication patients experiencing VA (1.18±0.10 versus 0.92±0.05, P=0.019). In combined analysis of ICM cohorts, R2I2 ≥1.03 identified subjects with significantly higher risk of VA or death (43%) compared with R2I2 <1.03 (11%) (P=0.004). Conclusions In this pilot study, we have developed a novel VA risk marker, R2I2, and have shown that it correlated with a structural measure of arrhythmic risk and predicted risk of VA or death in patients with ICM. R2I2 may improve risk stratification and merits further evaluation. (J Am Heart Assoc. 2012;1:e001552 doi: 10.1161/JAHA.112.001552.)
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Affiliation(s)
- William B Nicolson
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK (W.B.N., P.D.B., N.J.S., G.A.N.) ; National Institute for Health Research Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, UK (W.B.N., G.P.M., N.J.S., G.A.N.)
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8
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A pilot study of QT interval analysis in overweight and obese youth. Appl Nurs Res 2011; 25:218-21. [PMID: 21255976 DOI: 10.1016/j.apnr.2010.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 11/16/2010] [Indexed: 11/21/2022]
Abstract
This descriptive pilot study examined if manual corrected QT (QTc) interval measures obtained from a standard 12-lead electrocardiogram (ECG) correlated with automated 24-hour ambulatory Holter QTc measures in 30 overweight and obese youth aged 12-17 years. In addition, we sought to determine if a significant difference existed between the means of manual 12-lead ECG versus automated 24-hour ambulatory Holter measures. Spearman's rho correlation coefficient revealed there was little if any correlation between manual 12-lead ECG and automated 24-hour ambulatory Holter QTc measures (r = .179, p = .345). In addition, a significant difference existed between QTc measures obtained from the manual 12-lead ECG in comparison to the automated 24-hour ambulatory Holter measures (p = .01). The manual 12-lead ECG and automated 24-hour ambulatory Holter analysis methods should not be used for comparison of QTc measures in overweight and obese youth.
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Haapalahti P, Viitasalo M, Perhonen M, Väänänen H, Mäkijärvi M, Swan H, Toivonen L. Comparison of QT peak and QT end interval responses to autonomic adaptation in asymptomatic LQT1 mutation carriers. Clin Physiol Funct Imaging 2010; 31:209-14. [PMID: 21138517 PMCID: PMC3121965 DOI: 10.1111/j.1475-097x.2010.01002.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Background LQT1 subtype of long QT syndrome is characterized by defective IKs, which is intrinsically stronger in the epicardium than in the midmyocardial region. Electrocardiographic QT peak and QT end intervals may reflect complete repolarization of epicardium and midmyocardial region of the ventricular wall, respectively. Repolarization abnormalities in LQT1 carriers may therefore be more easily detected in the QT peak intervals. Methods Asymptomatic KCNQ1 mutation carriers (LQT1, n = 9) and unaffected healthy controls (n = 8) were studied during Valsalva manoeuvre, mental stress, handgrip and supine exercise. Global QT peak and QT end intervals derived from 25 simultaneous electrocardiographic leads were measured beat to beat with an automated method. Results In unaffected subjects, the percentage shortening of QT peak was greater than that of QT end during mental stress and during the recovery phases of Valsalva and supine exercise. In LQT1 carriers, the percentage shortening of the intervals was similar. At the beginning of Valsalva strain under abrupt endogenous sympathetic activation, QT peak shortened in LQT1 but not in control patients yielding increased electrocardiographic transmural dispersion of repolarization in LQT1. Conclusions In asymptomatic KCNQ1 mutation carriers, repolarization abnormalities are more evident in the QT peak than in the QT end interval during adrenergic adaptation, possibly related to transmural differences in the degree of IKs block.
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Affiliation(s)
- Petri Haapalahti
- Department of Cardiology, Laboratory of Clinical Physiology, Helsinki University Hospital, Helsinki, Finland.
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Abstract
Prolonged QT interval is associated with the generation of life-threatening arrhythmias and sudden death. However, neither the relation between QT duration and heart rate, nor the association between mental stress and QT time has been clarified. Aim: The relationship between QT duration and smoking, cardiovascular reactivity, and mental stress as well as newer methods of QT correction were studied. Methods: In six laboratory experiments 166 volunteers were studied. Smoking, treadmill exercise, mental arithmetic and videogame were applied as stressors. Besides fixed formulae, study and subject-specific QT correction methods were also used. Results: 1. Bazett formula is not appropriate to compare QT durations. 2. Acute smoking has no effect on QT time. 3. QT changes are related to cardiovascular reactivity. 4. Mental stress may induce QT prolongation. 5. Bifid T waves often develop during mental and isometric stress. Conclusions: New methods for QT correction are more reliable than preformed formulae. QT prolongation and bifid T waves may be the links between mental stress and life threatening arrhythmias.
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Affiliation(s)
- Gábor Andrássy
- Budapesti Szent Ferenc Kórház Budapest Széher u. 73. 1021
- Semmelweis Egyetem Elméleti Orvostudományok Doktori Iskola Budapest
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Yasuda K, Hayashi G, Horie A, Taketani T, Yamaguchi S. Clinical and electrophysiological features of Japanese pediatric long QT syndrome patients with KCNQ1 mutations. Pediatr Int 2008; 50:611-4. [PMID: 19261104 DOI: 10.1111/j.1442-200x.2008.02623.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND The purpose of the present paper was to determine the clinical and electrophysiological features of Japanese pediatric long QT syndrome (LQTS) patients with KCNQ1 mutations (LQT1). METHODS KCNQ1 mutations were analyzed in 13 Japanese pediatric patients with prolonged QT interval on electrocardiogram (ECG). These LQT1 patients were reviewed, retrospectively, for the presence of past and family histories of LQTS-related cardiac events, other complications, and their ECG findings evaluated at rest and during exercise). RESULTS KCNQ1 mutations were identified in eight patients (61.5%) from six unrelated families. Four missense mutations were identified in seven patients and an insertion/deletion in one. The mutations were located in the transmembrane domain in four patients and the C-terminal domain in four. Syncope did not occur in patients with the C-terminal domain mutations up to the age of 6-9 years, but family members of patients with the C-terminal domain mutations had a history of syncope in their elementary school days. Compared with a non-LQTS control group, peak heart rate (HR) on exercise and the HR increase during exercise were significantly lower in the LQT1 group (LQT1 vs control, 155 +/- 16 beats/min vs 182 +/- 13 beats/min, P < 0.01, 66 +/- 16 beats/min vs 99 +/- 24 beats/min, P < 0.01, respectively). CONCLUSIONS The risk of LQTS-related cardiac events may not be different in pediatric LQT1 patients with C-terminal domain mutations than in patients with transmembrane domain mutations. Possible sinus node dysfunction or a poor HR response to sympathetic stimulation has been suggested in pediatric LQT1 patients.
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Affiliation(s)
- Kenji Yasuda
- Department of Pediatrics, Shimane University, Faculty of Medicine, Shimane, Japan.
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12
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Haapalahti P, Viitasalo M, Perhonen M, Mäkijärvi M, Väänänen H, Oikarinen L, Salorinne Y, Swan H, Toivonen L. Electrocardiographic interventricular dispersion of repolarization during autonomic adaptation in LQT1 subtype of long QT syndrome. SCAND CARDIOVASC J 2008; 42:130-6. [PMID: 18365896 DOI: 10.1080/14017430701805419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVES In LQT1 subtype of inherited long QT syndrome, repolarization abnormalities originating from defective I(Ks) render patients vulnerable to ventricular arrhythmia during sudden sympathetic activation. Experimental studies show lower I(Ks) density and longer action potential duration in left (LV) than in right (RV) ventricle. We studied interventricular dispersion of repolarization in patients with I(Ks) defect during autonomic tests. DESIGN We measured interventricular (difference of QT intervals between LV and RV type leads) and transmural electrocardiographic dispersion of repolarization from 25-lead electrocardiograms in nine asymptomatic KCNQ1 mutation carriers (LQT1) and eight controls during rest, Valsalva maneuver, mental stress, sustained handgrip and supine exercise. RESULTS LQT1 carriers showed increased interventricular dispersion of repolarization (13+/-9 ms vs. 4+/-4 ms, p=0.03) during all tests. Valsalva strain increased the difference between the study groups. In LQT1 carriers, interventricular dispersion of repolarization correlated weakly with electrocardiographic transmural dispersion of repolarization. CONCLUSIONS Asymptomatic KCNQ1 mutation carriers exhibit increased and by abrupt sympathetic activation augmented interventricular difference in electrocardiographic repolarization times. Interventricular and transmural repolarization dispersion behave similarly in patients with I(Ks) defect.
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Affiliation(s)
- Petri Haapalahti
- Department of Cardiology, Helsinki University Hospital, Helsinki, Finland.
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