Brugada syndrome

First introduced as a new clinical entity in 1992, the Brugada syndrome is associated with a relatively high risk of sudden death in young adults, and occasionally in children and infants. Recent years have witnessed a striking proliferation of papers dealing with the clinical and basic aspects of the disease. Characterized by a coved-type ST-segment elevation in the right precordial leads of the electrocardiogram (ECG), the Brugada syndrome has a genetic basis that thus far has been linked only to mutations in SCN5A, the gene that encodes the alpha-subunit of the sodium channel. The Brugada ECG is often concealed, but can be unmasked or modulated by a number of drugs and pathophysiological states including sodium channel blockers, a febrile state, vagotonic agents, tricyclic antidepressants, as well as cocaine and propranolol intoxication. Average age at the time of initial diagnosis or sudden death is 40 +/- 22, with the youngest patient diagnosed at 2 days of age and the oldest at 84 years. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of the Brugada syndrome, incorporating the results of two recent consensus conferences. Controversies with regard to risk stratification and newly proposed pharmacologic strategies are discussed.     

Brugada syndrome

The Brugada syndrome, first described as a new clinical entity in 1992, is characterized by ST segment elevation in right precordial leads (V1 to V3) with a high risk of sudden death. The clinical presentation of this syndrome is distinguished by a male predominance and the appearance of lethal arrhythmic events. In 1998, mutation in SCN5A, the alpha-subunit of the sodium channel, linked the etiology of this syndrome had been discovered. The proper diagnostic criteria has been proposed by the European Society of Cardiology based on the currently available clinical data of this syndrome. In the symptomatic patients often need an implantable cardioverter defibrillator (ICD) because of a high incidence of recurrence.     

The Brugada syndrome

Brugada syndrome describes the syndrome of sudden cardiac death in the setting of the following electrocardiographic findings: right bundle branch block pattern with ST-segment elevation in the right precordial leads. The right bundle branch block may be incomplete while the ST segment elevation is minimal. The electrocardiographic findings are not constant. Patients suspected of having Brugada syndrome should be promptly referred for electrophysiological testing and treatment. Rapid referral and placement of an implantable cardioverter defibrillator (ICD) is associated with an excellent prognosis, whereas failure to diagnose this condition is associated with a high risk for sudden death. Therefore, it is imperative that all emergency physicians be familiar with the typical ECG manifestations of Brugada syndrome. Three illustrative cases are presented with a review of the syndrome.     

Brugada syndrome in children

Brugada syndrome is an inherited arrhythmia associated with characteristic ST elevation in the right precordial leads and sudden cardiac death. The average age of sudden cardiac death is 40 years; reported pediatric cases remain rare. Genetic testing and increased disease awareness may result in many more children being diagnosed with Brugada syndrome.     

Brugada syndrome mimicking acute coronary syndrome

This report describes a 42-year-old man with Brugada syndrome (BRS) mimicking acute coronary syndrome. Chest pain, near-syncope, and electrocardiographic changes were thought initially to be due to ischemia. Cardiac catheterization was performed. The coronary arteries and left ventricular function were normal. Careful review of his electrocardiogram suggested a diagnosis of BRS. BRS may be confused with acute coronary syndrome; early recognition of this syndrome is essential, as implantable cardioverter-defibrillator therapy may be life-saving.     

Pericarditis mimicking Brugada syndrome

Introduction

Brugada syndrome (BrS) is a genetic heart disorder due to alteration of the ion channels function that causes an impaired in the cardiac conduction system. It is characterized by an abnormal electrocardiogram pattern and may be complicated by malignant ventricular arrhythmias.Pericarditis is an inflammation of the pericardium and 90% of isolated cases of acute pericarditis are idiopathic or viral. Acute pericarditis may appears with chest pain, fever, pericardial friction rub, and cardiac tamponade. Moreover, widespread ST segment changes occur due to involvement of the underlying epicardium.

Wolff-Parkinson-White syndrome concomitant with asymptomatic Brugada syndrome

A 29-year-old man was referred for electrophysiological testing and radiofrequency ablation because of repeated episodes of palpitation over 2 years. A 12-lead electrocardiogram during sinus rhythm showed manifest Wolff-Parkinson-White syndrome and during palpitation showed narrow QRS tachycardia at a rate of 213 beats/min. Following successful radiofrequency ablation of the left anterolateral accessory pathway, sustained atrial fibrillation was induced by atrial extrastimulation. Cibenzoline (2 mg/kg body weight) was injected to terminate atrial fibrillation. ST-T segment elevation in the right precordial leads was observed following cibenzoline administration. Ventricular fibrillation was reproducibly induced by ventricular extrastimuli (S1: 600 ms, S2: 220 ms, S3: 210 ms).     

Fever unmasking the Brugada syndrome

This case report describes a 66-year-old woman with severe polymorphic ventricular tachycardia and syncope during a febrile state. The electrocardiogram revealed a right bundle branch block and pattern of elevated ST segment in the anterior and inferior leads similar to the Brugada syndrome. These electrocardiographic anomalies disappeared when the temperature returned to normal. The administration of procainamide reproduced the electrocardiographic changes. An electrophysiological study using two extrastimuli induced ventricular tachycardia. An automatic defibrillator was implanted.     

Brugada syndrome unmasked by febrile illness

The ionic mechanisms responsible for the electrocardiographic phenotype of the Brugada syndrome are temperature dependent. This report describes a healthy young man with ECG changes typical of Brugada syndrome that were unmasked during a febrile illness.     

Brugada综合征和致心律失常型右室心肌病

Brugada综合征和致心律失常型右室心肌病（ARVC）两者临床表现相似,均可导致恶性心律失常和猝死。该文就Brugada综合征和ARVC在临床表现、心电图特征等方面进行了对比分析,并对两者的诊断、鉴别诊断及治疗进行简单介绍。     

Recent advances in the treatment of Brugada syndrome

Introduction: Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by ST-segment elevation in right precordial ECG leads and associated with sudden cardiac death in young adults. The ECG manifestations of BrS are often concealed but can be unmasked by sodium channel blockers and fever.

Areas covered: Implantation of a cardioverter defibrillator (ICD) is first-line therapy for BrS patients presenting with prior cardiac arrest or documented VT. A pharmacological approach to therapy is recommended in cases of electrical storm, as an adjunct to ICD and as preventative therapy. The goal of pharmacological therapy is to produce an inward shift to counter the genetically-induced outward shift of ion channel current flowing during the early phases of the ventricular epicardial action potential. This is accomplished by augmentation of I_Ca using □□adrenergic agents or phosphodiesterase III inhibitors or via inhibition of I_to. Radiofrequency ablation of the right ventricular outward flow tract epicardium is effective in suppressing arrhythmogenesis in BrS patients experiencing frequent appropriate ICD-shocks.

Expert commentary: Understanding of the pathophysiology and approach to therapy of BrS has advanced considerably in recent years, but there remains an urgent need for development of cardio-selective and ion-channel-specific I_to blockers for treatment of BrS.