What it means
It measures how long the electrical signal takes to travel from the atria through the AV node to the ventricles. On a standard ECG strip it is normally 0.12 to 0.20 seconds (three to five small boxes). A longer PR interval means the signal is held up in the AV node, as in first-degree heart block; digoxindih-JOK-sinA drug that makes the heart beat more strongly and more slowly.Full entry , beta blockers and calcium channel blockers are among the drugs that can lengthen it.
For the nurse
Measure the PR interval on every rhythm strip and compare it with earlier strips. Report a new or lengthening PR interval, especially in a client taking drugs that slow conduction.
At a glance
| Normal range | 0.12–0.20 seconds |
|---|---|
| Also written | PR intervals |
Related terms
electrocardiogram
A test that records the heart's electrical activity as waves on paper or a screen.
sinus bradycardia
A regular heart rhythm that starts normally in the sinus node but runs slower than 60 beats per minute.
U wave
A small, rounded wave that sometimes follows the T wave on an ECG.