Final answer:
In a 12-lead ECG, augmented leads aVR, aVL, and aVF utilize electrodes on the limbs—the right arm, left arm, and left leg, with the right arm acting as a reference. These leads complement the chest leads to provide a detailed view of the heart's electrical activity, aiding in the diagnosis of cardiac conditions.
Step-by-step explanation:
An electrocardiogram (ECG or EKG) measures the electrical activity of the heart to show its rhythm and activity. In a 12-lead ECG, ten electrodes are used in a standardized manner. For the augmented leads, which are aVR, aVL, and aVF, the electrodes are placed on the limbs. Specifically, one electrode is placed on each arm and one on the left leg, making use of the right arm as a reference.
The augmented leads help record the heart's electrical activity from various angles, complementing the six chest leads and providing a comprehensive understanding of the heart's function. The chest leads are placed in specific locations across the chest, following anatomical landmarks to ensure accurate readings. The limb leads and the chest leads together make it possible to detect abnormalities such as heart infarcts, which can be identified in one or more lead potentials.
Comparing recent ECGs to older ones allows doctors to detect subtle changes or gradual damage to the heart. In addition to clinical ECGs, portable ECG monitors such as the Holter monitor are now available that can be worn by the patient to continuously monitor the heart's activity, typically for a 24-hour period.