Figure 3. The four walls of the left ventricle and the ECG leads that reflect these walls. The term “contiguous leads” refers to any two leads that are anatomical neighbours. Hence, ST elevation in leads V1 and V2 would fulfill criteria for STEMI. ST elevation in V2 and V3 would also fuflfill criteria for STEMI because these two leads are also anatomical neighbours, even if this illustration shows that V2 reflects the septal wall and V3 the anterior wall.