What defines a bipolar limb lead?

What defines a bipolar limb lead?

• A. It consists of three limb electrodes
• B. A measurement between 2 limb electrodes
• C. A measurement between chest and limb electrodes
• D. A single electrode measuring voltage

Answer: (B)

A bipolar limb lead is specifically defined as a measurement between two limb electrodes. In the context of EKGs, bipolar leads assess the electrical potential difference between two points, allowing for the evaluation of the heart's electrical activity from different angles. This type of lead captures both the positive and negative electrode's contributions, providing a more comprehensive overview of the heart’s electrical behavior.

In the standard limb lead system, leads I, II, and III are considered bipolar since they each record the electrical activity between two electrodes located on the limbs. For example, lead I measures the potential difference between the left arm and right arm, highlighting how electrical signals travel across the heart.

The other choices either misrepresent the nature of a bipolar lead or describe other types of leads or measurements. For instance, the option mentioning three limb electrodes describes the entire limb electrode system rather than the bipolar measurement. Another choice discusses the relationship between chest and limb electrodes, which pertains to unipolar leads instead. Finally, a single electrode measuring voltage would refer to a unipolar lead, which only involves one active electrode and a reference electrode and does not capture the relative potential from two sources.