Cellular and ionic basis of J-wave syndromes.

J-wave syndromes are disorders of ventricular repolarization characterized by prominent J waves on the ECG and have the potential to predispose affected individuals to lethal ventricular arrhythmias. These disorders share a common cellular mechanism with prominent Ito in ventricular epicardium. This current causes transmural dispersion of repolarization and the generation of phase 2 reentry, leading to short-coupled extrasystoles and VF. Several autonomic, chemical, and hormonal factors modulate Ito and are therefore vital in attenuating or increasing the arrhythmic potential of these syndromes. Future research should focus on evaluating the arrhythmogenic potential of patients with pathogenic genotypes and/or J waves and no history of VF.