Inherited Cardiac Arrhythmia Syndrome: Role of Potassium Channels

Abstract

Potassium channels are the main contributors to repolarizing outward currents acting during cardiac action potential. Quantitative and qualitative variations in the expression and biophysical properties of voltage-gated potassium channels seem to be largely responsible for action potential differences observed among regions of the heart and between normal and diseased myocardium. This review discusses the role of potassiumchannel dysfunctions in inherited cardiac arrhythmia syndromes classified as channelopathies caused by either loss-of-function mutations (long QT syndrome [LQTS] and Andersen-Tawil syndrome [ATS]) or gain-of-function mutations in genes encoding potassium channels (short QT syndrome [SQTS] and familial atrial fibrillation [AF]). Early repolarization syndrome and Brugada syndrome are not included in the gain-offunction mutations although they can also be caused by a gain of function in the cardiac KATP Kir 6.1 channel (KCNJ8-S422L) ; they are discussed by Yan and Antzelevitch elsewhere in this issue.