Electrode Placement: Getting It Right from the Start

Correct placement of ECG electrodes is essential for accurate interpretation. A standard 12-lead ECG uses 10 physical electrodes:

• 4 limb electrodes: Right arm (RA), left arm (LA), right leg (RL – neutral/ground), and left leg (LL)
• 6 chest (precordial) electrodes: V1 to V6, placed across the anterior chest wall

Chest leads are positioned as follows:

• V1: 4th intercostal space, right sternal edge
• V2: 4th intercostal space, left sternal edge
• V3: Midway between V2 and V4
• V4: 5th intercostal space, midclavicular line
• V5: Horizontal with V4, anterior axillary line
• V6: Horizontal with V4/V5, mid-axillary line
  

Incorrect lead placement can significantly distort the ECG trace. It may falsely alter the height and morphology of waves, leading to missed or overcalled diagnoses — especially in suspected myocardial infarction. In practice, if ST elevation appears muted or absent due to poor lead placement, PPCI-capable hospitals may refuse urgent transfers, delaying time-critical reperfusion.

Ensure electrodes are placed on clean, dry skin — avoiding bony areas or excessive hair. A well-positioned ECG not only improves diagnostic accuracy but also instils confidence in your clinical handover and supports faster, safer patient care.