Latest progress in electrocardiographic J wave and J wave syndrome

Early repolarization syndrome,Brugada syndrome and Brugada syndrome variant(including sudden cardiac death associated with a prominent J waves in the inferior leads and ventricular fibrillation associated with a prominent J waves and ST segment elevation in the inferior leads)are identical in terms of their ionic and cytological mechanism and may be referred to an Ito-mediated J-wave syndrome.The only difference among these clinical entities is the difference in Ito densities and associated J wave sizes.Ito densities and wave sizes play a key role in arrhythmogenesis.In the leads V1～V3,the J wave and ST segment elevation are the signs that indicate a high risk of sudden cardiac death,i.e.,the Brugada syndrome.In contrast,the J wave and ST segment elevation in V4～V6 is generally considered to be benign,i.e.,the early repolarization syndrome.In other words,J wave that involve the right ventricle are arrhythmogenic;those that involve the left ventricular anterolateral regions are generally benign.Prominent J waves and ST segment elevation involve the left ventricular inferior wall may serve as an important diagnostic sign to detect high risk individuals with a history of unexplained syncope in the condition of sudden cardiac death.