Ion Channels, the QT Interval, and Arrhythmias

Aberrations in genes encoding for ion channels have been shown to underlie a number of cardiac arrhythmia syndromes, hitherto classified as idiopathic. These aberrations, inherited and congenital, may lead to dysfunction of channels with resultant abnormal current characteristics. In addition, a variety of stimuli may cause altered expression of these genes. Because prolongation of the action potential (and the QT-interval) is often the result, patients are at risk for the occurrence of arrhythmias based on reentry and the development of abnormal impulse initiation. Molecular dissection of the inherited syndromes has led to rapid progress in our understanding of basic knowledge about ion channel function and its relation to channel structure. This progress is undoubtedly of benefit for the understanding of the repolarization changes in more common conditions and will become of benefit to many more patients who suffer from therapy resistant arrhythmias.