What Is an Electrocardiogram?

By jolene

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5. Electrodes, Leads, and Positioning

The electrodes in an ECG refer to the conductive pads that are placed on the skin. A pair of electrodes measures the electrical signal between the two locations. A pair of electrodes forms a lead. In most ECG, 10 electrodes (conductive pads) are placed on the skin to form 12 ECG leads. The leads can be divided in to limb, augmented limb, and chest leads. The RA electrode is placed on the right arm, LA on the left arm, RL on the right leg, and LL on the left leg. The other 6 electrodes are placed on the chest with V1 at the fourth intercostal space to the right of the sternum, V2 at fourth intercostal space to the left of the sternum, V3 between leads V2 and V4, V4 at the fifth intercostal space midclavicular line, V5 next to V4 in the left anterior axillary line, and V6 next to V5 in the mid-axillary line