Ion channels and ventricular arrhythmias: cellular and ionic mechanisms underlying the Brugada syndrome

Brugada syndrome is characterized by ST segment elevation in the right precordial leads, V1-V3 (unrelated to ischemia or structural disease), normal QT intervals, apparent right bundle branch block, and sudden cardiac death, particularly in men of Asian origin. An autosomal dominant mode of inheritance with variable expression has been described. The only gene thus far linked to the Brugada syndrome is the cardiac sodium channel gene, SCN5A. The possible cellular and ionic basis for these features of the Brugada syndrome are discussed. Strong sodium channel block, among other modalities, has been shown to be capable of inducing epicardial and transmural dispersion of repolarization, thus providing the substrate for the development of phase 2 and circus movement reentry, which underlies ventricular tachycardia/ventricular fibrillation.