Apart from the standard 12 leads, additional leads are sometimes useful in the diagnosis of various conditions. These include right sided chest leads, posterior leads and elevated leads. Although ideally these should be recorded by placing electrodes in these locations, they can be derived from the standard leads. Here, right sided (V3R, V4R, V5R and V6R), posterior (V7, V8 and V9) and elevated leads (V1+1, V2+1, V1+2, V2+2) are derived and displayed. See here for more details.