J Wave Syndromes.

J wave syndromes are a collection of clinical entities characterized by accentuation of the I_to-mediated J wave, early repolarization and ST segment elevation. Although the risks of sudden cardiac death of these syndromes differ with respect to the magnitude and location of abnormal J wave manifestation and ST segment elevation, they share with a common ionic and cellular mechanism and their responses to heart rate and autonomic influences are similar. The congenital forms of J wave syndromes include early repolarization syndrome, which can be categorized into three subtypes according to J wave location and the risk of arrhythmogenesis, and the Brugada syndrome. J wave syndromes can be acquired in certain pathological conditions with augmentation of J-wave like hypothermia and acute ST segment elevation myocardial infarction. In the chapter, we attempt to summarize current state of knowledge about J-wave syndromes, bridging basic and clinical aspects. [ABSTRACT FROM AUTHOR]