What is the normal PA interval?

What is the normal PA interval?

• A. 25-55 ms
• B. 10-20 ms
• C. 60-80 ms
• D. 100-150 ms

Answer: (A)

The PA interval reflects intra-atrial conduction time—from the onset of atrial activation (P wave) to the local atrial electrogram at the recording site. It represents atrial conduction independent of AV nodal or ventricular conduction, so it is shorter than the PR interval. In a healthy heart, the normal PA interval is about 25–55 ms. Values longer than this suggest slowed intra-atrial conduction, while values well below this range aren’t typical of meaningful atrial conduction times. Therefore 25–55 ms is the standard normal range.

The PA interval reflects intra-atrial conduction time—from the onset of atrial activation (P wave) to the local atrial electrogram at the recording site. It represents atrial conduction independent of AV nodal or ventricular conduction, so it is shorter than the PR interval.

In a healthy heart, the normal PA interval is about 25–55 ms. Values longer than this suggest slowed intra-atrial conduction, while values well below this range aren’t typical of meaningful atrial conduction times. Therefore 25–55 ms is the standard normal range.