Which of the following is NOT a type of lead polarity?

The choice indicating quadrupolar as the correct answer highlights its absence as a recognized lead polarity type in standard pacing systems.

Lead polarity generally refers to the configuration of electrodes used in a pacing system to deliver electrical impulses. There are two main types of lead polarities: unipolar and bipolar.

Unipolar leads consist of a single active electrode and a case electrode, allowing for stimulation with a simpler design. Bipolar leads, on the other hand, utilize two electrodes (tip and ring), which create a more localized electrical field and reduce the risk of induced interference from distant tissues.

Although there are concepts related to multiple electrodes (like multipolar), the term quadrupolar is not commonly used to describe a distinct configuration in the same way unipolar and bipolar are categorized. Thus, quadrupolar does not fit into the established lead polarity types, making it the correct answer to the question of which is NOT a type of lead polarity.