Right-sided and posterior leads

Definition

Extra chest electrode positions that extend the standard 12-lead ECG to the right ventricle and the posterobasal (inferobasal) wall of the left ventricle, areas the standard leads show poorly. Right-sided leads (V3R to V6R) mirror the standard left-sided positions on the right chest; V4R (right fifth intercostal space, midclavicular line) is the most useful lead for right ventricular infarction, where ST elevation of at least 0.05 mV (at least 0.1 mV in men under 30) supports the diagnosis. Posterior leads V7 (left posterior axillary line), V8 (left midscapular line) and V9 (left paraspinal border) lie in the same horizontal plane as V6; ST elevation of at least 0.05 mV in them (at least 0.1 mV in men under 40) supports infarction of this wall, which on the standard 12 leads may appear only as ST depression with tall R waves in V1 to V3.

Clinical notePosterior infarction may appear on the standard 12-lead only as ST depression with tall R waves in V1 to V3, the mirror image of the ST elevation that leads V7 to V9 record directly.