"Brugada" syndrome: clinical data and suggested pathophysiological mechanism.

Abstract

The occurrence of ventricular fibrillation (VF) in the absence of any structural heart disease is classified as “primary electrical disease” or (in the absence of any relevant findings) “idiopathic VF.” This diagnosis implies that the arrhythmogenic substrate is inherent to the excitable and conducting properties of the heart. With the exception of a positive family history, demographic variables are, as a rule, not very helpful in establishing the diagnosis of primary electrical disease.1 The paradigm of primary electrical disease is the long-QT syndrome (LQTS), in which altered ionic channel function secondary to mutations in genes encoding ion channels has been shown to underlie QT-interval prolongation.2 3 In 1992, Brugada and Brugada4 described 8 patients with a history of aborted sudden death and a distinct ECG pattern, consisting of right bundle-branch block (RBBB) with ST-segment elevation in the right precordial leads (V1, V2, and V3, Figure 1⇓) and normal QT interval in the absence of any structural heart disease (as determined by routine clinical, biochemical, echocardiographic, and angiographic examinations). In 4 of the reported patients, a family history was suspected. Figure 1. ECG tracings of 1 patient originally described by Brugada and Brugada.4 Tracings show RBBB with ST-segment elevation in right precordial leads. There is marked left axis deviation, suggesting presence of left anterior hemiblock. In presence of RBBB, QTc is prolonged (482 ms). Patients with these unique ECG abnormalities have been recognized as a distinct subgroup in male Thai patients presenting with cardiac arrest due to VF.5 In northeastern Thailand, sudden unexpected death, typically occurring during sleep, is a leading cause of death in young men, and 40% of these patients have a family history of sudden death.6 The suspected inherited occurrence of the entity strongly suggested possible involvement …