What is the significance of the term "unipolar" in relation to limb leads?

What is the significance of the term "unipolar" in relation to limb leads?

• A. It refers to the use of a single limb for measurement
• B. It indicates that the lead measures only positive activity
• C. It means the lead only records negative potentials
• D. It signifies that it is a secondary lead

Answer: (B)

The term "unipolar" is significant in relation to limb leads because it indicates that the lead measures electrical activity with reference to a neutral point, typically the Wilson central terminal, which is derived from averaging the signals from the other limb leads. In a unipolar lead, this configuration focuses on detecting the positive electrical activity from a single electrode, allowing for a more direct observation of the electrical impulses in that specific area.

In this context, the unipolar lead captures the positive potentials generated during cardiac depolarization, which is crucial for diagnosing various cardiac conditions. This measurement emphasizes the activity occurring at the electrode site rather than a comparison between two active electrodes, thereby providing valuable information about the heart's function from that specific viewpoint.

The other options do not accurately capture the essence of what "unipolar" refers to in the context of limb leads, as they may misinterpret the role of electrical potentials in the measurement process.