Experimental mechanisms of arrhythmias in brugada syndrome

This chapter reviewed the mechanisms of Brugada syndrome (BS) as we explored in experimental models created with drug-induced channelopathies in isolated, arterially perfused canine right ventricular tissues. These experimental studies revealed the mechanisms of arrhythmogenicity in terms of repolarization heterogeneity both inside the epicardium and across the right ventricular outflow tract and mechanisms of its sensitivity to temperature, rate dependency, T wave alternans, and fragmented QRS. These experimental models also illustrated the origins of the characteristic features of the typical BS electrocardiograms and the genotype-phenotype relationships in BS with Na+ or Ca2+ channelopathies. We also explored the effects of blocking the transient outward current, Ito, and of treatments with quinidine or isoproterenol on the electrophysiologic heterogeneity and arrhythmias in these models. Ablation and body surface mapping in patients with BS supported these experimental findings.