Brugada syndrome is diagnosed by identifying characteristic patterns on an electrocardiogram. The pattern seen on the ECG includes ST elevation in leads V1-V3 with a right bundle branch block (RBBB) appearance. There may be evidence of a slowing of electrical conduction within the heart, as shown by a prolonged PR interval. These patterns may be present all the time, but may appear only in response to particular drugs (see below), when the person has a fever, during exercise, or as a result of other triggers. The ECG pattern may become more obvious by performing an ECG in which some of the electrodes are placed in different positions from usual, specifically by placing leads V1 and V2 higher up the chest wall in the 1st or 2nd intercostal spaces.