CVS Practice Test 2025 – Complete Exam Preparation

The bipolar limb leads are indeed labeled as I, II, and III. These leads are derived from the difference in electrical potential between pairs of electrodes placed on the limbs, which allows them to measure the heart's electrical activity from different angles.

Lead I measures the potential difference between the left arm and right arm electrodes, providing a horizontal view of the heart’s electrical activity. Lead II records the difference between the left leg and right arm electrodes, which offers a diagonal view. Lead III captures the potential difference between the left leg and left arm, contributing additional information about cardiac electrical activity.

This designation is important for interpreting electrocardiograms (ECGs), as the bipolar leads give a clear perspective on the heart's function and assist in diagnosing various cardiac conditions. The other options refer to different types of leads: aVR, aVL, and aVF are unipolar leads (not bipolar), and V1, V2, and V3 represent precordial (chest) leads that provide a different perspective on the electrical activity of the heart, while "Lead 1, Lead 2, Lead 3" is not the standard nomenclature for these bipolar limb leads.