网页2023年2月7日 · The 12-lead ECG consists of four limb leads (RA, RL, LA, LL) and six precordial (chest) leads (V1, V2, V3, V4, V5, and V6). A Guide to 12-Lead ECG Placement. Placing ECG leads can be a challenging process, but with a few simple steps, it can be easy to ensure accurate lead placement. Here is a step …