Here are the 12 electrodes used in an electrocardiogram (ECG):
1. RA – Right arm
2. LA – Left arm
3. RL – Right leg
4. LL – Left leg
5. V1 – 4th intercostal space at right sternal margin
6. V2 – 4th intercostal space at the left sternal margin
7. V3 – Between V2 and V4
8. V4 – 5th intercostal space at midclavicular line
9. V5 – Same horizontal plane as V4 at left anterior axillary line
10. V6 – Same horizontal plane as V4 at left midaxillary line
11. AVR – Records voltage between RA and an average of LA, LL
12. AVL – Records voltage between LA and an average of RA, LL
13. AVF – Records voltage between LL and average of LA, RAThe 12 leads allow electrical activity to be recorded from different angles across the heart to help diagnose cardiac conditions. The limb leads (RA, LA, RL, LL) form the vertices of Einthoven’s triangle.
