PR interval

Question 1

What is the PR interval (PRI)?

Answer 1

The distance from the beginning of the P wave to the beginning of the QRS complex.

The PRI indicates the time for an impulse to traverse the atria and AV junction.

Question 2

What is the normal duration of the PR interval?

Answer 2

0.12 to 0.20 seconds (120 to 200 milliseconds).

This duration corresponds to three to five small boxes on the ECG strip.

Question 3

What does the PR segment represent?

Answer 3

The amount of time the AV node delays transmission of atrial activity to the ventricles.

This delay is crucial for proper heart function.

Question 4

What occurs during the PR segment that cannot be seen on the ECG?

Answer 4

The wave produced by repolarization of the atria.

This repolarization is too small to be detected on the ECG.

Question 5

What happens to the PR segment when the AV node is diseased or hypoxic?

Answer 5

The PR segment can become elongated.

This elongation can indicate underlying cardiac issues.