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Moras E, Gandhi K, Narasimhan B, Brugada R, Brugada J, Brugada P, Krittanawong C. Genetic and Molecular Mechanisms in Brugada Syndrome. Cells 2023; 12:1791. [PMID: 37443825 PMCID: PMC10340412 DOI: 10.3390/cells12131791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/15/2023] Open
Abstract
Brugada syndrome is a rare hereditary arrhythmia disorder characterized by a distinctive electrocardiogram pattern and an elevated risk of ventricular arrhythmias and sudden cardiac death in young adults. Despite recent advances, it remains a complex condition, encompassing mechanisms, genetics, diagnosis, arrhythmia risk stratification, and management. The underlying electrophysiological mechanism of Brugada syndrome requires further investigation, with current theories focusing on abnormalities in repolarization, depolarization, and current-load match. The genetic basis of the syndrome is strong, with mutations found in genes encoding subunits of cardiac sodium, potassium, and calcium channels, as well as genes involved in channel trafficking and regulation. While the initial discovery of mutations in the SCN5A gene provided valuable insights, Brugada syndrome is now recognized as a multifactorial disease influenced by several loci and environmental factors, challenging the traditional autosomal dominant inheritance model. This comprehensive review aims to provide a current understanding of Brugada syndrome, focusing on its pathophysiology, genetic mechanisms, and novel models of risk stratification. Advancements in these areas hold the potential to facilitate earlier diagnosis, improve risk assessments, and enable more targeted therapeutic interventions.
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Affiliation(s)
- Errol Moras
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Kruti Gandhi
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Bharat Narasimhan
- Debakey Cardiovascular Institute, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Ramon Brugada
- Cardiology, Cardiac Genetics Clinical Unit, Hospital Universitari Josep Trueta, Hospital Santa Caterina, 17007 Girona, Spain
- Cardiovascular Genetics Center and Clinical Diagnostic Laboratory, Institut d’Investigació Biomèdica Girona-IdIBGi, 17190 Salt, Spain
| | - Josep Brugada
- Cardiovascular Institute, Hospital Clínic, 08036 Barcelona, Spain
- Pediatric Arrhythmia Unit, Hospital Sant Joan de Déu, 08950 Barcelona, Spain
- Department of Medicine, University of Barcelona, 08036 Barcelona, Spain
| | - Pedro Brugada
- Cardiovascular Division, Free University of Brussels (UZ Brussel) VUB, B-1050 Brussels, Belgium
- Medical Centre Prof. Brugada, B-9300 Aalst, Belgium
- Arrhythmia Unit, Helicopteros Sanitarios Hospital (HSH), Puerto Banús, 29603 Marbella, Spain
| | - Chayakrit Krittanawong
- Cardiology Division, NYU Langone Health and NYU School of Medicine, New York, NY 10016, USA
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Takahashi H, Takagi M, Yoshio T, Yoh M, Shiojima I. Analysis of site-specific late potentials using a novel Holter signal-averaged electrocardiography in patients with Brugada syndrome. Heart Rhythm 2022; 19:1650-1658. [PMID: 35562054 DOI: 10.1016/j.hrthm.2022.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 04/26/2022] [Accepted: 05/04/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND The utility of late potentials on signal-averaged electrocardiography (SAECG) for risk stratification in patients with Brugada syndrome (BrS) remains controversial. Late potentials on conventional SAECG with Frank leads may be insufficiently sensitive to detect site-specific late potentials in right precordial leads. OBJECTIVE The purpose of this study was to evaluate the utility of site-specific late potentials using a novel unipolar Holter-SAECG system for risk stratification in patients with BrS. METHODS Consecutive symptomatic (n = 20) and asymptomatic (n = 21) patients with BrS who underwent investigation using conventional SAECG and a novel unipolar Holter-SAECG system were enrolled. We evaluated clinical characteristics and outcomes and compared late potentials on the 2 SAECGs between both groups and patients with and without cardiac events (CEs) (sudden cardiac death or sustained ventricular tachyarrhythmias) during the follow-up period. RESULTS During mean follow-up of 76 months, 10 patients (24%) had CEs. There were no significant differences in late potentials on conventional SAECG between symptomatic and asymptomatic patients. On the Holter-SAECG system, RMS40 in lead V2 in the third intercostal space (3L-V2) at the nighttime was significantly lower in the symptomatic group than in the asymptomatic group (5.5 ± 0.8 μV and 8.2 ± 0.8 μV, respectively; P = .027). Univariate analysis of predictive values for CE showed that hazard ratios of daytime and nighttime RMS40 in lead 3L-V2 of <7.7 μV and <6.1 μV were 7.58 and 6.14, respectively. CONCLUSION Site-specific late potentials in lead 3L-V2 measured using the novel Holter-SAECG system may be a useful marker for high-risk patients with BrS.
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Affiliation(s)
- Hiroki Takahashi
- Department of Medicine II, Kansai Medical University, Osaka, Japan
| | - Masahiko Takagi
- Department of Medicine II, Kansai Medical University, Osaka, Japan.
| | - Takuro Yoshio
- Department of Medicine II, Kansai Medical University, Osaka, Japan
| | - Masue Yoh
- Department of Medicine II, Kansai Medical University, Osaka, Japan
| | - Ichiro Shiojima
- Department of Medicine II, Kansai Medical University, Osaka, Japan
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Zoppo F, Gagno G, Perazza L, Cocciolo A, Mugnai G, Vaccari D, Calzolari V. Electroanatomic voltage mapping for tissue characterization beyond arrhythmia definition: A systematic review. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2021; 44:1432-1448. [PMID: 34096635 DOI: 10.1111/pace.14288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/17/2021] [Accepted: 05/30/2021] [Indexed: 11/28/2022]
Abstract
Three-dimensional (3D) reconstruction by means of electroanatomic mapping (EAM) systems, allows for the understanding of the mechanism of focal or re-entrant arrhythmic circuits, which can be identified by means of dynamic (activation and propagation) and static (voltage) color-coded maps. However, besides this conventional use, EAM may offer helpful anatomical and functional information for tissue characterisation in several clinical settings. Today, data regarding electromechanical myocardial viability, scar detection in ischaemic and nonischaemic cardiomyopathy and arrhythmogenic right ventricle dysplasia (ARVC/D) definition are mostly consolidated, while emerging results are becoming available in contexts such as Brugada syndrome and cardiac resynchronisation therapy (CRT) implant procedures. As part of an invasive procedure, EAM has not yet been widely adopted as a stand-alone tool in the diagnostic path. We aim to review the data in the current literature regarding the use of 3D EAM systems beyond the definition of arrhythmia.
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Affiliation(s)
- Franco Zoppo
- Elettrofisiologia, U.O.C. di Cardiologia, Ospedale Civile Gorizia, Gorizia, Italy
| | - Giulia Gagno
- Dipartimento di Cardiologia, Azienda Sanitaria Universitaria Giuliano Isontina, ed Università degli Studi di Trieste, Trieste, Italy
| | - Luca Perazza
- Elettrofisiologia, U.O.C. di Cardiologia, Ospedale Civile Gorizia, Gorizia, Italy
| | - Andrea Cocciolo
- Elettrofisiologia, U.O.C. di Cardiologia, Ospedale Civile Gorizia, Gorizia, Italy
| | - Giacomo Mugnai
- Elettrofisiologia, U.O.C di Cardiologia, Ospedale Civile Arzignano, Vicenza, Italy
| | - Diego Vaccari
- Elettrofisiologia, U.O.C di Cardiologia, Ospedale Civile Feltre, Belluno, Italy
| | - Vittorio Calzolari
- Elettrofisiologia, U.O.C di Cardiologia, Ospedale Civile Treviso, Treviso, Italy
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Lopez-Blazquez M, Field E, Tollit J, Walsh H, Addis A, French N, Starling L, Kaski JP. Clinical significance of inferolateral early repolarisation and late potentials in children with Brugada Syndrome. J Electrocardiol 2021; 66:79-83. [PMID: 33831794 DOI: 10.1016/j.jelectrocard.2021.03.011] [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: 01/18/2021] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 11/30/2022]
Abstract
INTRODUCTION The clinical utility of inferolateral early repolarisation (ER) and late potentials (LP) in children with Brugada Syndrome (BrS) has not been previously evaluated. The aim of this study was to determine the prevalence of electrocardiographic (ECG) abnormalities in children with BrS, and to investigate their relationship with clinical outcomes. METHODS 43 patients with BrS and 47 controls aged ≤18 undergoing systematic clinical and ECG evaluation, including signal-averaged ECG (SAECG) and pharmacological provocation testing, between 2003 and 2019 were included. RESULTS Four patients with BrS (9%) presented with a spontaneous type 1 Brugada pattern; the remaining 39 (91%) were diagnosed following ajmaline provocation testing. Twelve BrS patients (28%) had late potentials (LP) on SAECG compared to 1 (2%) in controls (p = 0.001). LP were more common in 5 patients with a high-risk phenotype (60% vs 24%) but this was not statistically significant. Twelve patients with BrS (28%) had inferolateral early repolarisation (ER) and 2 (5%) had fractionated QRS (f-QRS), but there were no statistically-significant differences with controls in these parameters. A significant arrhythmia (non-sustained ventricular tachycardia or atrial fibrillation) was seen in 4 patients (9%). CONCLUSIONS This study shows a high prevalence of SAECG abnormalities in children with BrS compared with controls, but this was not significantly associated with a high-risk phenotype.
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Affiliation(s)
- Maria Lopez-Blazquez
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom; Gregorio Marañon Children Hospital, Madrid, Spain
| | - Ella Field
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Jennifer Tollit
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Helen Walsh
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Amy Addis
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Nichola French
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Luke Starling
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Juan Pablo Kaski
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom; UCL Institute of Cardiovascular Science, London, United Kingdom.
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Zoppo F, Gagno G, Perazza L, Cocciolo A, Mugnai G, Vaccari D, Calzolari V. Electroanatomic voltage mapping and characterisation imaging for "right ventricle arrhythmic syndromes" beyond the arrhythmia definition: a comprehensive review. Int J Cardiovasc Imaging 2021; 37:2347-2357. [PMID: 33761057 DOI: 10.1007/s10554-021-02221-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 03/08/2021] [Indexed: 11/30/2022]
Abstract
Three-dimensional (3D) reconstruction by means of electroanatomic mapping (EAM) systems, allows for the understanding of the mechanism of focal or re-entrant arrhythmic circuits along with pacing techniques. However, besides this conventional use, EAM may offer helpful anatomical and functional information. Data regarding electromechanical scar detection in ischaemic (and nonischaemic) cardiomyopathy are mostly consolidated, while emerging results are becoming available in contexts such as arrhythmogenic right ventricular dysplasia (ARVC/D) definition and Brugada syndrome. As part of an invasive procedure, EAM has not yet been widely adopted as a stand-alone tool in the diagnostic path. We aim to review the current literature regarding the use of 3D EAM systems for right ventricle (RV) functional characterisation beyond the definition of arrhythmia.
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Affiliation(s)
- Franco Zoppo
- Elettrofisiologia, U.O.C. Di Cardiologia, Ospedale Civile Gorizia, Gorizia, Italy.
| | - Giulia Gagno
- Azienda Sanitaria Universitaria Giuliano Isontina - Dipartimento di Cardiologia Trieste, Trieste, Italy
| | - Luca Perazza
- Elettrofisiologia, U.O.C. Di Cardiologia, Ospedale Civile Gorizia, Gorizia, Italy
| | - Andrea Cocciolo
- Elettrofisiologia, U.O.C. Di Cardiologia, Ospedale Civile Gorizia, Gorizia, Italy
| | - Giacomo Mugnai
- Elettrofisiologia, U.O.C Di Cardiologia, Ospedale Civile Arzignano, Vicenza, Italy
| | - Diego Vaccari
- Elettrofisiologia, U.O.C Di Cardiologia, Ospedale Civile Feltre, Belluno, Italy
| | - Vittorio Calzolari
- Elettrofisiologia, U.O.C Di Cardiologia, Ospedale Civile Treviso, Treviso, Italy
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Li W, Yin L, Shen C, Hu K, Ge J, Sun A. SCN5A Variants: Association With Cardiac Disorders. Front Physiol 2018; 9:1372. [PMID: 30364184 PMCID: PMC6191725 DOI: 10.3389/fphys.2018.01372] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 09/10/2018] [Indexed: 12/19/2022] Open
Abstract
The SCN5A gene encodes the alpha subunit of the main cardiac sodium channel Nav1.5. This channel predominates inward sodium current (INa) and plays a critical role in regulation of cardiac electrophysiological function. Since 1995, SCN5A variants have been found to be causatively associated with Brugada syndrome, long QT syndrome, cardiac conduction system dysfunction, dilated cardiomyopathy, etc. Previous genetic, electrophysiological, and molecular studies have identified the arrhythmic and cardiac structural characteristics induced by SCN5A variants. However, due to the variation of disease manifestations and genetic background, impact of environmental factors, as well as the presence of mixed phenotypes, the detailed and individualized physiological mechanisms in various SCN5A-related syndromes are not fully elucidated. This review summarizes the current knowledge of SCN5A genetic variations in different SCN5A-related cardiac disorders and the newly developed therapy strategies potentially useful to prevent and treat these disorders in clinical setting.
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Affiliation(s)
- Wenjia Li
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lei Yin
- Department of Urology, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Cheng Shen
- Department of Cardiology, The Affiliated Hospital of Jining Medical University, Jining, China
| | - Kai Hu
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Junbo Ge
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, Shanghai, China.,Department of Cardiology, Institute of Biomedical Science, Fudan University, Shanghai, China
| | - Aijun Sun
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, Shanghai, China.,Department of Cardiology, Institute of Biomedical Science, Fudan University, Shanghai, China
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Nagamoto Y, Fujii Y, Morita Y, Ueda Y, Miyake Y, Yamane K, Fujiwara M, Mito S, Watari Y, Tamekiyo H, Okimoto T, Muraoka Y, Hayashi Y. Atrial electrical abnormality in patients with Brugada syndrome assessed by signal-averaged electrocardiography. Indian Heart J 2017; 69:714-719. [PMID: 29174247 PMCID: PMC5717291 DOI: 10.1016/j.ihj.2017.05.008] [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: 12/13/2016] [Revised: 04/28/2017] [Accepted: 05/02/2017] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Ventricular fibrillation and atrial fibrillation are well-known arrhythmias in patients with Brugada syndrome. This study evaluated the characteristics of the atrial arrhythmogenic substrate using the signal-averaged electrogram (SAECG) in patients with Brugada syndrome. METHODS SAECGs were performed during normal sinus rhythm in 23 normal volunteers (control group), 21 patients with paroxysmal atrial fibrillation (PAF; PAF group), and 21 with Brugada syndrome (Brugada group). RESULTS The filtered P wave duration (fPd) in the control, Brugada, and PAF groups was 113.9±12.9ms, 125.3±15.0ms, and 137.1±16.3ms, respectively. The fPd in the PAF group was significantly longer compared to that in the control and Brugada groups (p<0.05). The fPd in the Brugada group was significantly longer than that in the control group (p<0.05) and significantly shorter than that in the PAF group (p<0.05). CONCLUSION Patients with Brugada syndrome had abnormal P waves on the SAECG. The abnormal P waves on the SAECG in Brugada syndrome patients may have intermediate characteristics between control and PAF patients.
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Affiliation(s)
| | - Yuto Fujii
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Yuichi Morita
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Yusuke Ueda
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Yasuko Miyake
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Kenichi Yamane
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Mai Fujiwara
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Shinji Mito
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Yuichiro Watari
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | | | - Tomokazu Okimoto
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Yuji Muraoka
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Yasuhiko Hayashi
- Division of Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
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Nakagawa K, Nagase S, Morita H, Wada T, Tanaka M, Murakami M, Watanabe A, Nishii N, Nakamura K, Kusano KF, Ito H, Ohe T. Impact of premature activation of the right ventricle with programmed stimulation in Brugada syndrome. J Cardiovasc Electrophysiol 2017; 29:71-78. [DOI: 10.1111/jce.13336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/31/2017] [Accepted: 09/05/2017] [Indexed: 11/29/2022]
Affiliation(s)
- Koji Nakagawa
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine; Dentistry and Pharmaceutical Sciences; Okayama Japan
| | - Satoshi Nagase
- Divisions of Arrhythmia and Electrophysiology; National Cerebral and Cardiovascular Center; Suita Japan
| | - Hiroshi Morita
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine; Dentistry and Pharmaceutical Sciences; Okayama Japan
| | - Tadashi Wada
- Department of Cardiology; Iwakuni Medical Center; Iwakuni Japan
| | - Masamichi Tanaka
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine; Dentistry and Pharmaceutical Sciences; Okayama Japan
| | - Masato Murakami
- Department of Cardiovascular Medicine; Shonan Kamakura General Hospital; Kamakura Japan
| | - Atsuyuki Watanabe
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine; Dentistry and Pharmaceutical Sciences; Okayama Japan
| | - Nobuhiro Nishii
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine; Dentistry and Pharmaceutical Sciences; Okayama Japan
| | - Kazufumi Nakamura
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine; Dentistry and Pharmaceutical Sciences; Okayama Japan
| | - Kengo F. Kusano
- Divisions of Arrhythmia and Electrophysiology; National Cerebral and Cardiovascular Center; Suita Japan
| | - Hiroshi Ito
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine; Dentistry and Pharmaceutical Sciences; Okayama Japan
| | - Tohru Ohe
- Okayama City General Medical Center; Okayama Japan
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Martini B, Martini N, Dorantes Sánchez M, Márquez MF, Zhang L, Fontaine G, Nava A. [Clues of an underlying organic substrate in the Brugada Syndrome]. ARCHIVOS DE CARDIOLOGIA DE MEXICO 2016; 87:49-60. [PMID: 28038951 DOI: 10.1016/j.acmx.2016.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 10/06/2016] [Accepted: 10/11/2016] [Indexed: 10/20/2022] Open
Affiliation(s)
- Bortolo Martini
- Unidad Cardiovascular, Hospital Alto Vicentino, Santorso, Italia.
| | - Nicolò Martini
- Colegio Médico, Universidad de Medicina de Ferrara, Ferrara, Italia
| | - Margarita Dorantes Sánchez
- Servicio de Arritmias y Estimulación Cardiaca, Instituto de Cardiología y Cirugía Cardiovascular, La Habana, Cuba
| | - Manlio F Márquez
- Servicio de Electrocardiología, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de México, México
| | - Li Zhang
- Instituto Lankenau de Investigación Médica, Colegio Médico Jefferson, Filadelfia, Estados Unidos
| | - Guy Fontaine
- Unidad de Ritmología, Instituto de Cardiología, Hospital de La Pitié-Salpêtrière, París, Francia
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ten Sande JN, Coronel R, Conrath CE, Driessen AH, de Groot JR, Tan HL, Nademanee K, Wilde AA, de Bakker JM, van Dessel PF. ST-Segment Elevation and Fractionated Electrograms in Brugada Syndrome Patients Arise From the Same Structurally Abnormal Subepicardial RVOT Area but Have a Different Mechanism. Circ Arrhythm Electrophysiol 2015; 8:1382-92. [DOI: 10.1161/circep.115.003366] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 10/14/2015] [Indexed: 11/16/2022]
Abstract
Background—
Brugada syndrome (BrS) is characterized by a typical ECG pattern. We aimed to determine the pathophysiologic basis of the ST-segment in the BrS-ECG with data from various epicardial and endocardial right ventricular activation mapping procedures in 6 BrS patients and in 5 non-BrS controls.
Methods and Results—
In 7 patients (2 BrS and 5 controls) with atrial fibrillation, an epicardial 8×6 electrode grid (interelectrode distance 1 mm) was placed epicardially on the right ventricular outflow tract (RVOT) before video-assisted thoracoscopic surgical pulmonary vein isolation. In 2 other BrS patients, endocardial, epicardial RV (CARTO), and body surface mapping was performed. In 2 additional BrS patients, we performed decremental preexcitation of the RVOT before endocardial RV mapping. During video-assisted thoracoscopic surgical pulmonary vein isolation and CARTO mapping, BrS patients (n=4) showed greater activation delay and more fractionated electrograms in the RVOT region than controls. Ajmaline administration increased the region with fractionated electrograms, as well as ST-segment elevation. Preexcitation of the RVOT (n=2) resulted in ECGs that supported the current-to-load mismatch hypothesis for ST-segment elevation. Body surface mapping showed that the area with ST-segment elevation anatomically correlated with the area of fractionated electrograms and activation delay at the RVOT epicardium.
Conclusions—
ST-segment elevation and epicardial fractionation/conduction delay in BrS patients are most likely related to the same structural subepicardial abnormalities, but the mechanism is different. ST-segment elevation may be caused by current-to-load mismatch, whereas fractionated electrograms and conduction delay are expected to be caused by discontinuous conduction in the same area with abnormal myocardium.
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Affiliation(s)
- Judith N. ten Sande
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Ruben Coronel
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Chantal E. Conrath
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Antoine H.G. Driessen
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Joris R. de Groot
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Hanno L. Tan
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Koonlawee Nademanee
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Arthur A.M. Wilde
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Jacques M.T. de Bakker
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
| | - Pascal F.H.M. van Dessel
- From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L’Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute,
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11
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Abstract
More than 20 years have passed since the description of Brugada syndrome as a clinical entity. The original case series depicted patients who all had coved ST-segment elevation in the right precordial leads, associated with a high risk of sudden death and no apparent structural heart disease. As subsequent registry data were published, it became apparent that the spectrum of risk is wide, with the majority of patients classified as low risk. Two consensus documents have been published that will continue to be updated. Despite intense research efforts, many controversies still exist over its pathophysiology and the risk stratification for sudden death. Management continues to be challenging with a lack of drug therapy and high complication rates from implantable cardioverter defibrillators. In this review, we highlight the current state-of-the-art therapies and their controversies.
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Affiliation(s)
- Anthony Li
- Cardiovascular Sciences Research Centre, St George's University of London, Cranmer Terrace, London, SW17 0RE, UK
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13
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Abstract
Two decades ago, a series of 8 idiopathic ventricular fibrillation patients who each had an abnormal ECG (right bundle branch block with coved-type ECG), but otherwise had normal hearts were described by Brugada and Brugada. Since then, the clinical entity has become known as Brugada syndrome (BS). Shortly thereafter, mutations of the SCN5A gene that encodes for the α-subunit of the sodium channel were found, galvanizing the field of ion channelopathies following in the footsteps of the breakthrough in long QT syndrome. Over the past 20 years, extensive research in this field has produced major progress toward better understanding of BS and the gaining of knowledge of the genetic background, pathophysiology and new management. Two consensus reports were published to help define the diagnostic criteria, risk stratification and management of BS patients. However, there are controversies. In this review, we will share our experiences of BS patients in Thailand and discuss advances in many aspects of the syndrome (ie, genetics and pathophysiology) and some of these pertinent controversies, as well as new treatment of the syndrome with catheter ablation.
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Affiliation(s)
- Gumpanart Veerakul
- Cardiovascular Research and Prevention Center, Bhumibol Adulyadej Hospital and Pacific Rim Electrophysiology Research, Bangkok, Thailand
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14
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Bhar-Amato J, Nunn LM, Lambiase PD. A review of the mechanisms of ventricular arrhythmia in brugada syndrome. Indian Pacing Electrophysiol J 2010; 10:410-25. [PMID: 20930959 PMCID: PMC2933369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Brugada syndrome (BrS) is characterised by the triad of coved ST elevation, lethal ventricular arrhythmia in an apparently structurally normal heart. The precise mechanisms responsible for the coved ST elevation and ventricular arrhythmias in this disease have been debated since its initial description in 1992. Indeed the recent recognition of early repolarisation J wave disorders linked to primary VF broadens the mechanistic importance of BrS in sudden cardiac death. It may lie on a spectrum of early repolarisation pathology which is becoming increasingly recognised as a marker of premature cardiovascular death. Mechanistically, abnormalities of both depolarisation and repolarisation in the right ventricular outflow tract, and heterogeneities of conduction between the endocardium and epicardium have been implicated in the electrographic manifestations of BrS and arrhythmogenesis.The initial belief of BrS as a single autosomal dominant ion channel disorder has been challenged. It has become apparent that sodium channel mutations only account for a maximum of 30% of cases and structural myocardial abnormalities have now been described in what was previously thought to be a purely functional condition. It is highly probable that BrS is an umbrella diagnosis for a number of conduction and repolarisation abnormalities which manifest as this syndrome and the coved ST elevation represents the final common pathway of both ion channel and structural derangements. This review will discuss the issues surrounding the mechanisms of lethal arrhythmia in BrS and summarise both basic science and clinical research findings.
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15
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Lambiase PD, Ahmed AK, Ciaccio EJ, Brugada R, Lizotte E, Chaubey S, Ben-Simon R, Chow AW, Lowe MD, McKenna WJ. High-density substrate mapping in Brugada syndrome: combined role of conduction and repolarization heterogeneities in arrhythmogenesis. Circulation 2009; 120:106-17, 1-4. [PMID: 19564561 DOI: 10.1161/circulationaha.108.771401] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Two principal mechanisms are thought to be responsible for Brugada syndrome (BS): (1) right ventricular (RV) conduction delay and (2) RV subepicardial action potential shortening. This in vivo high-density mapping study evaluated the conduction and repolarization properties of the RV in BS subjects. METHODS AND RESULTS A noncontact mapping array was positioned in the RV of 18 BS patients and 20 controls. Using a standard S(1)-S(2) protocol, restitution curves of local activation time and activation recovery interval were constructed to determine local maximal restitution slopes. Significant regional conduction delays in the anterolateral free wall of the RV outflow tract of BS patients were identified. The mean increase in delay was 3-fold greater in this region than in control (P=0<0.001). Local activation gradient was also maximally reduced in this area: 0.33+/-0.1 (mean+/-SD) mm/ms in BS patients versus 0.51+/-0.15 mm/ms in controls (P<0.0005). The uniformity of wavefront propagation as measured by the square of the correlation coefficient, r(2), was greater in BS patients versus controls (0.94+/-0.04 versus 0.89+/-0.09 [mean+/-SD]; P<0.05). The odds ratio of BS hearts having any RV segment with maximal restitution slope >1 was 3.86 versus controls. Five episodes of provoked ventricular tachycardia arose from wave breaks originating from RV outflow tract slow-conduction zones in 5 BS patients. CONCLUSIONS Marked regional endocardial conduction delay and heterogeneities in repolarization exist in BS. Wave break in areas of maximal conduction delay appears to be critical in the initiation and maintenance of ventricular tachycardia. These data indicate that further studies of mapping BS to identify slow-conduction zones should be considered to determine their role in spontaneous ventricular arrhythmias.
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Affiliation(s)
- P D Lambiase
- Heart Hospital, University College Hospital, University College London, London, UK.
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16
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Yodogawa K, Morita N, Kobayashi Y, Takayama H, Ohara T, Katoh T, Takano T. High-frequency potentials developed in wavelet-transformed electrocardiogram as a novel indicator for detecting Brugada syndrome. Heart Rhythm 2006; 3:1436-44. [PMID: 17161786 DOI: 10.1016/j.hrthm.2006.08.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2006] [Accepted: 08/22/2006] [Indexed: 10/24/2022]
Abstract
BACKGROUND A reliable alternative method for detecting Brugada syndrome is desirable because the diagnosis of Brugada syndrome using 12-lead ECG is not optimal. OBJECTIVES The purpose of this study was to assess the usefulness of the wavelet-transformed ECG in detecting Brugada syndrome. METHODS The study consisted of 15 patients with Brugada syndrome and 15 healthy subjects (control group). The parameters on the signal-averaged ECG and the frequency components recorded from the wavelet-transformed ECG were compared between the two groups. Measurements were repeated after pilsicainide infusion in the two groups of patients, after an isoproterenol infusion following pilsicainide injection, and after administration of cilostazol in the group of patients with Brugada syndrome. RESULTS The positive rate of late potentials was 80% in the Brugada syndrome group and 0% in the control group (P <.01). The high-frequency components (80-150 Hz) were developed in the Brugada syndrome group to a greater extent than in the control group, but the low-frequency components (10-50 Hz) did not differ (mean peak power at 80 Hz; 713 +/- 36 vs 488 +/- 60, P <.001). After pilsicainide injection, high-frequency components significantly increased in both groups. However, after isoproterenol and cilostazol administration, high-frequency components significantly decreased but remained higher than in the control group (80 Hz; 655 +/- 40 vs 488 +/- 60, P <.001). The sensitivity of the development of high-frequency components in detecting Brugada syndrome was higher than that of signal-averaged ECG (100% vs 80%), but specificity remained high and similar (100% for both methods). CONCLUSION Abnormally high-frequency components recorded from the wavelet-transformed ECG might be a novel factor in detecting Brugada syndrome.
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Affiliation(s)
- Kenji Yodogawa
- First Department of Internal Medicine, Nippon Medical School, Tokyo, Japan
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Burri H, Chevalier P, Fayn J, Forlini MC, Rubel P, Touboul P. Beat-to-beat variations of the electrocardiogram in survivors of sudden death without structural heart disease. J Electrocardiol 2006; 39:310-4. [PMID: 16777518 DOI: 10.1016/j.jelectrocard.2005.10.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Indexed: 11/23/2022]
Abstract
AIM We sought to determine whether survivors of sudden death without structural heart disease have beat-to-beat electrocardiographic (ECG) characteristics at the microvolt and at the millisecond level that differ from normal subjects. METHODS We studied patients at our implantable cardioverter defibrillator clinic who had been resuscitated from ventricular fibrillation with no evidence of underlying structural heart disease. Continuous 10-minute high-resolution unfiltered digital surface ECGs at 1000-Hz sampling rate were acquired in these subjects and in a group of healthy volunteers. We then analyzed different parameters of beat-to-beat variations in duration, amplitudes and vectors of the QRS complex, and the T wave using a locally developed program (Comparative Analysis of ECGs, Vectocardiograms, and their Interpretation with Auto-Reference to the patient) and compared them between the 2 groups. RESULTS Thirteen patients (7 men; age, 46 +/- 16 years) were studied. Standard ECGs were unremarkable in 7 patients and suggestive of Brugada syndrome in the 6 others. The control group consisted of 23 age- and sex-matched subjects (13 men; age, 41 +/- 10 years). Although the QRS parameters showed only few differences between the 2 groups, there were several differences in parameters evaluating repolarization. CONCLUSION High-resolution ECGs show distinct beat-to-beat variations in parameters of repolarization in survivors of sudden death without structural heart disease, as compared with normal subjects. These findings may reflect increased electrical instability and should be evaluated for stratifying arrhythmic risk in asymptomatic individuals.
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Affiliation(s)
- Haran Burri
- Unité 50, Hôpital Louis-Pradel, Lyon, France.
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18
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Gehi AK, Duong TD, Metz LD, Gomes JA, Mehta D. Risk Stratification of Individuals with the Brugada Electrocardiogram: A Meta-Analysis. J Cardiovasc Electrophysiol 2006; 17:577-83. [PMID: 16836701 DOI: 10.1111/j.1540-8167.2006.00455.x] [Citation(s) in RCA: 256] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES We performed a meta-analysis of prognostic studies of patients with a Brugada ECG to assess predictors of events. BACKGROUND The Brugada syndrome is an increasingly recognized cause of idiopathic ventricular fibrillation; however, there is wide variation in the prognosis of patients with the Brugada ECG. METHODS AND RESULTS We retrieved 30 prospective studies of patients with the Brugada ECG, accumulating data on 1,545 patients. Summary estimates of the relative risk (RR) of events (sudden cardiac death [SCD], syncope, or internal defibrillator shock) for a variety of potential predictors were made using a random-effects model. The overall event rate at an average of 32 months follow-up was 10.0% (95% CI 8.5%, 11.5%). The RR of an event was increased (P < 0.001) among patients with a history of syncope or SCD (RR 3.24 [95% CI 2.13, 4.93]), men compared with women (RR 3.47 [95% CI 1.58, 7.63]), and patients with a spontaneous compared with sodium-channel blocker induced Type I Brugada ECG (RR 4.65 [95% CI 2.25, 9.58]). The RR of events was not significantly increased in patients with a family history of SCD (P = 0.97) or a mutation of the SCN5A gene (P = 0.18). The RR of events was also not significantly increased in patients inducible compared with noninducible by electrophysiologic study (EPS) (RR 1.88 [95% CI 0.62, 5.73], P = 0.27); however, there was significant heterogeneity of the studies included. CONCLUSIONS Our findings suggest that a history of syncope or SCD, the presence of a spontaneous Type I Brugada ECG, and male gender predict a more malignant natural history. Our findings do not support the use of a family history of SCD, the presence of an SCN5A gene mutation, or EPS to guide the management of patients with a Brugada ECG.
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Affiliation(s)
- Anil K Gehi
- The Zena and Michael A. Wiener Cardiovascular Institute, Mount Sinai School of Medicine, New York, New York 10029, USA.
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Kawaguchi T, Nomura M, Tujikawa T, Nakaya Y, Ito S. 123I-metaiodo-benzylguanidine myocardial scintigraphy in the Brugada-type ECG. THE JOURNAL OF MEDICAL INVESTIGATION 2006; 53:95-102. [PMID: 16538001 DOI: 10.2152/jmi.53.95] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The degree of ST-segment elevation and amplitude of J waves, which may change in patients with the Brugada-type electrocardiogram (ECG) over time, are influenced by autonomic nervous activity and the administration of antiarrhythmic drugs. In the present study, we evaluated whether the shape of ST-segment elevation in patients with a Brugada-type ECG might alter the parameters of an 123I-MIBG myocardial scintigraphy and body surface signal-averaged ECG (SAECG). The subjects consisted of 12 patients with a Brugada-type ECG and 15 healthy volunteers (N group). The patients with a Brugada-type ECG were classified into the following 2 groups based on the type of ST-segment elevation: 6 patients with the coved type ST-segment elevation (C group), and 6 patients with the saddle-back type ST-segment elevation (S group). Planar and SPECT images were obtained 15 minutes (early images) and 3 hours (delayed images) after the administration of 123I-MIBG, respectively. In addition, the washout rate (% WR) of 123I-MIBG was obtained in a bull's eye map of the SPECT image. There were no significant differences in the early H/M ratio between the C and S groups. In the C group, however, there were some patients who showed a decreased accumulation or defect of 123I-MIBG in the planar and SPECT images. Furthermore, in contrast to the N and S groups, the C group showed a decreased delayed H/M ratio and increased % WR. SAECG did not show any significant differences between the S and C groups. These results of the present study suggest that the shape of ST-segment elevation may be associated with myocardial autonomic nervous function. In addition, the electric heterogeneity of the action potential in the right ventricular epicardial myocardium, which is frequently influenced by autonomic nervous activity, is closely associated with the development of Brugada syndrome.
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Affiliation(s)
- Takashi Kawaguchi
- Department of Digestive and Cardiovascular Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Japan
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Tukkie R, Sogaard P, Vleugels J, de Groot IKLM, Wilde AAM, Tan HL. Delay in right ventricular activation contributes to Brugada syndrome. Circulation 2004; 109:1272-7. [PMID: 14993143 DOI: 10.1161/01.cir.0000118467.53182.d1] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Although Brugada syndrome revolves around reduced net depolarizing force, the electrophysiological mechanisms of its defining features (right precordial ST-segment elevation and ventricular tachyarrhythmias) remain unresolved. Two proposed mechanisms are (1) right ventricular (RV) conduction delay and (2) selective and significant RV subepicardial action potential shortening. Both mechanisms must cause disparate contractile changes: delay in RV contraction and reduction of contractile force, respectively. We aimed to establish the electrophysiological mechanism of Brugada syndrome by studying the timing and force of RV contraction. METHODS AND RESULTS Using tissue Doppler echocardiography, we studied how these contractile variables change on induction of the characteristic ST-segment changes of Brugada syndrome by flecainide challenge. Accordingly, we studied patients in whom flecainide induced these changes (inducible) and those in whom these changes were not induced (control). We found that (1) the occurrence of a positive response (coved-type ST elevation) after flecainide coincides with delay in the onset of contraction between the RV and left ventricle (LV); (2) the extent of contraction delay between RV and LV correlates with the magnitude of ST elevation; and (3) RV ejection time (duration of RV ejection phase) shortens as the Brugada ECG pattern emerges. CONCLUSIONS These results indicate that both proposed mechanisms of Brugada syndrome may be operative.
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Affiliation(s)
- Raymond Tukkie
- Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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