Longer Repolarization in the Epicardium at the Right Ventricular Outflow Tract Causes Type 1 Electrocardiogram in Patients With Brugada Syndrome

Nagase, Satoshi; Kusano, Kengo; Morita, Hiroshi; Nishii, Nobuhiro; Banba, Kimikazu; Watanabe, Atsuyuki; Hiramatsu, Shigeki; Nakamura, Kazufumi; Sakuragi, Satoru; Ohe, Tohru

doi:10.1016/j.jacc.2007.10.059

Cited by 64 publications

(62 citation statements)

References 29 publications

(21 reference statements)

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“…Still, electrograms in proximity to the epicardial RVOT have been recorded simultaneously with endocardial RVOT electrograms in BrS patients with the use of a guide wire in the conus branch. 31 That study showed that ARI and RT were longer at RVOT epicardium than at RVOT endocardium after pilsicainide administration and that a delay in AT occurred. Although this method also has its limitations, it would have been valuable to study electrograms in this RV region.…”

Section: Limitationsmentioning

confidence: 91%

Slow and Discontinuous Conduction Conspire in Brugada Syndrome

Postema

Dessel

Bakker

et al. 2008

Circ: Arrhythmia and Electrophysiology

122

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Background-Brugada syndrome (BrS) is associated with lethal arrhythmias, which are linked to specific ST-segment changes (type-1 BrS-ECG) and the right ventricle (RV). The pathophysiological basis of the arrhythmias and type-1 BrS-ECG is unresolved. We studied the electrophysiological characteristics of the RV endocardium in BrS. Methods and Results-RV endocardial electroanatomical mapping and stimulation studies were performed in controls (nϭ12) and BrS patients with a type-1 (BrS-1, nϭ10) or type-2 BrS-ECG (BrS-2, nϭ12) during the studies. BrS-1 patients had prominent impairment of RV endocardial impulse propagation when compared with controls, as represented by: (1) prolonged activation-duration during sinus rhythm (86Ϯ4 versus 65Ϯ3 ms), (2) increased electrogram fractionation (1.36Ϯ0.04 versus 1.15Ϯ0.01 deflections per electrogram), (3) longer electrogram duration (83Ϯ3 versus 63Ϯ2 ms), (4) activation delays on premature stimulation (longitudinal: 160Ϯ26 versus 86Ϯ9 ms; transversal: 112Ϯ5 versus 58Ϯ6 ms), and (5) abnormal transversal conduction velocity restitution (42Ϯ8 versus 18Ϯ2 ms increase in delay at shortest coupling intervals). Wider and more fractionated electrograms were also found in BrS-2 patients. Repolarization was not different between groups. Conclusions-BrS-1 and BrS-2 patients are characterized by wide and fractionated electrograms at the RV endocardium.BrS-1 patients display additional conduction slowing during sinus rhythm and premature stimulation along with abnormal transversal conduction velocity restitution. These patients may thus exhibit a substrate for slow and discontinuous conduction caused by abnormal active membrane processes and electric coupling. Our findings support the emerging notion that BrS is not solely attributable to abnormal electrophysiological properties but requires the conspiring effects of conduction slowing and tissue discontinuities. (Circ Arrhythmia Electrophysiol. 2008;1:379-386.)

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Section: Limitationsmentioning

confidence: 91%

Slow and Discontinuous Conduction Conspire in Brugada Syndrome

Postema

Dessel

Bakker

et al. 2008

Circ: Arrhythmia and Electrophysiology

122

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“…In 2 studies, unipolar electrograms from the epicardium of the right ventricular outflow tract demonstrated no early repolarization during the ST-segment. 39,40 Similarly, monophasic action potentials recorded at the right ventricular epicardium during open heart surgery demonstrated no loss of dome or early repolarization. 41 Also, arrhythmias appeared to originate from the subendocardium rather than from the subepicardium during a mapping study.…”

Section: Limitations To the Concept Of The Brugada Syndrome As A Chanmentioning

confidence: 95%

The Brugada ECG Pattern

Hoogendijk

Opthof

Postema

et al. 2010

Circ: Arrhythmia and Electrophysiology

130

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I n 1992, Brugada and Brugada introduced a new clinical entity characterized by right precordial ST-segment elevation followed by a negative T-wave and a high incidence of ventricular fibrillation (VF) in the absence of structural heart disease. 1 The typical ECG anomaly is currently known as the Brugada ECG pattern and the conglomerate of features as the Brugada syndrome. Over the years, the Brugada syndrome has been recognized as an important cause of sudden cardiac death in young men, especially in Southeast Asia, 2 and has attracted much attention from researchers and clinicians alike. This has led to substantial progress in identification of modulating factors of the Brugada ECG pattern, the associated ventricular arrhythmias, and in the risk stratification of patients. 3 However, the development of effective therapeutic strategies has lagged behind. Currently, symptomatic treatment with implantable cardioverterdefibrillators (ICDs) is the mainstay in the prevention of sudden cardiac death, 3 although it is costly and associated with a high risk of complications. 4 The pathophysiological mechanism of the Brugada syndrome remains elusive, 5 and no single causal factor appears to link all patients. The Brugada ECG pattern is modulated by genetic mutations and pharmacological agents that alter the function of ion channels active during the early phases of the action potential. Furthermore, signs of right ventricular structural abnormalities are often found in patients with Brugada syndrome. The aim of this study is to review the available literature on the Brugada syndrome in an attempt to provide a unifying hypothesis of the mechanism of the Brugada syndrome. This unifying hypothesis should be able to explain the ECG pattern, the arrhythmogenic mechanism, their modulation by ion channels, and the relation of structural abnormalities to the Brugada syndrome. Is the Brugada Syndrome a Channelopathy?The Brugada syndrome was introduced shortly after the first demonstration of statistical linkage between the long-QT syndrome (LQTS) and a gene locus. 6 Since then, genetic mutations that alter ion channel functions and prolong the QT duration were linked with the LQTS. 7 These observations defined the LQTS as a channelopathy. In analogy with the LQTS, a hereditary pattern was suspected in half the Brugada syndrome cases. Additionally, no structural heart disease was demonstrated, suggesting that the Brugada syndrome also was a channelopathy. 1 Over the years, this analogy was substantiated by further observations of similarity with the LQTS. GeneticsGenetic mutations that alter ion channel functions have been identified in patients with Brugada syndrome. The first identified mutations were located in SCN5A, the gene encoding the ␣-subunit of the cardiac sodium channel, leading to reduced cardiac sodium current (I Na ). 8 The prevalence of SCN5A mutations is Ϸ20% 9 and is higher in patients with than without a family history of Brugada syndrome. 10 Recently, mutations in GPD1L 11 , a gene probably involved in the tra...

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“…This discriminating electrophysiologic mechanism is thought to be associated with ST-segment elevation (J wave) and T-wave inversion in this syndrome. In a human study using the activation recovery interval (ARI) method, Nagase et al demonstrated that the inverted T wave associated with the type 1 ECG is due to a preferential epicardial ARI prolongation secondary to accentuation of the action potential notch in the right ventricular outflow tract, 14 consistent with the results of the experimental study. The data obtained in previous studies support the results of the present study.…”

Section: Article P 844mentioning

confidence: 58%

ECG Marker of High-Risk in Asymptomatic Patients With Brugada Syndrome

Kusano

2011

Circ J

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Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp rugada syndrome (BS) is a distinct form of idiopathic ventricular fibrillation (VF) characterized by a unique ECG pattern consisting of ST elevation in the anterior precordial leads with/without right bundle branch blocklike morphology. 1 It is generally accepted that patients with the type 1 ECG pattern (coved type) and with ventricular tachyarrhythmias (symptomatic BS patients) must receive an implantable cardioverter defibrillator to prevent a second VF attack. 2 However, in those without syncope, family history or documented VF (asymptomatic BS patients), the best strategy is controversial because the prevalence of Brugada-type ECG change by daily medical check-ups has been reported to be approximately 0.1-1.0% in healthy subjects, but their prognosis is good compared with that of symptomatic patients. 3 However, some asymptomatic BS patients occasionally become symptomatic and sudden cardiac death can occur with the first VF attack. Therefore, a marker that can differentiate high-risk asymptomatic patients from low-risk asymptomatic patients is needed. To date, several invasive and noninvasive parameters have been proposed for identification of patients at risk of VF, including spontaneous type 1 ST elevation, 3 characteristics of the S wave, 4 presence of late potentials, 5 coexisting atrial fibrillation, 6 augmented ST elevation after exercise, 7 fragmented QRS wave, 8 early repolarization pattern in the inferior/lateral leads, 3 third intercostal ECG 9,10 and inducibility of VF using programmed electrical stimulation, but the usefulness of these indexes remains controversial. Article p 844The results of a study by Miyamoto et al published in the Journal 11 indicate the interesting possibility of using new ECG criteria for identifying high-risk asymptomatic BS patients. They performed computer-based ECG analysis for more than 100,000 patients and detected spontaneous type 1 ECG in 185 (0.18%) of the patients. Detailed examination was performed in 31 of these 185 patients, and 16 patients were diagnosed as high-risk BS (syncope: 87.5%, aborted

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Longer Repolarization in the Epicardium at the Right Ventricular Outflow Tract Causes Type 1 Electrocardiogram in Patients With Brugada Syndrome

Abstract: Our data provide support for the hypothesis that the negative T-wave associated with type 1 BrS ECG is due to a preferential prolongation of the epicardial AP secondary to accentuation of the AP notch in the region of the right ventricular outflow tract.

Cited by 64 publications

References 29 publications

Slow and Discontinuous Conduction Conspire in Brugada Syndrome

Slow and Discontinuous Conduction Conspire in Brugada Syndrome

The Brugada ECG Pattern

ECG Marker of High-Risk in Asymptomatic Patients With Brugada Syndrome

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