Cardiac Rhythms

Step 4 PR interval (PRi) ECG Interpretation

Description

Measurement of the PR interval reflects the amount of time from the beginning of atrial depolarization to the beginning of ventricular depolarization.
Plainly stated, PR interval measurement is from the beginning of the P wave to the beginning of the QRS complex.
The normal range for PR interval is: 0.12 – 0.20 seconds (3 to 5 small boxes)
It is important that you measure each PR interval on the rhythm strip.
Some tracings do not have the same PRi measurement from one cardiac complex to the next. Sometimes there is a prolonging pattern, sometimes not.
If the PR intervals are variable, report them as variable, but note if a pattern is present or not.

Analyze this tracing. What is the PR interval Measurement?

Reveal Answer

4 small boxes (4 X 0.04 second) = 0.16 second

Analyze this tracing. What is the PR interval Measurement?

Reveal Answer

Variable – inverted P wave has shorter PR, plus one complex has no P wave

Authors and Sources

Electrocardiography for Healthcare Professionals, 6th Edition Kathryn Booth and Thomas O'Brien
ISBN10: 1265013470, ISBN13: 9781265013479
McGraw Hill, 2023
Rapid Interpretation of EKG's, Sixth Edition
Dale Dublin
Cover Publishing Company
EKG Reference Guide
EKG.Academy
12 Lead EKG for Nurses: Simple Steps to Interpret Rhythms, Arrhythmias, Blocks, Hypertrophy, Infarcts, & Cardiac Drugs
Aaron Reed
Create Space Independent Publishing
Heart Sounds and Murmurs: A Practical Guide with Audio CD-ROM 3rd Edition
Elsevier-Health Sciences Division
Barbara A. Erickson, PhD, RN, CCRN
The Virtual Cardiac Patient: A Multimedia Guide to Heart Sounds, Murmurs, EKG Jonathan Keroes, David Lieberman
Publisher: Lippincott Williams & Wilkin)
ISBN-10: 0781784425; ISBN-13: 978-0781784429
Project Semilla, UCLA Emergency Medicine, EKG Training Breena R. Taira, MD, MPH
ECG Reference Guide
PracticalClinicalSkills.com