Cardiac Rhythms

Step 5 QRS Complex ECG Interpretation

Description

The QRS represents ventricular depolarization.
It is very important to analyze each QRS complex on the tracing and report the duration measurement and describe the shape (including any changes in shape).
As discussed earlier in step 3, when referring to P waves, remember changes in the shape of the waveform can indicate the locus of stimulation has changed or a different conduction pathway was followed. It is no different when analyzing the QRS complex.
The difference is that in step 3, we were looking at atrial activity. Now we are looking at ventricular activity.
Measure QRS complex from the beginning to the end of ventricular depolarization.

The normal duration of the QRS complex measures from: 0.06 – 0.10 second
When the QRS measurement is 0.12 seconds or greater it indicates a delay in the electrical impulse as it is passing through the ventricular conduction system
Abnormal duration QRS

Analyze this tracing. What is the QRS duration?

Reveal Answer

2 small boxes (2 X 0.04 second) = 0.08 second

Analyze this tracing. What is the QRS duration?

Reveal Answer

4 1/2 small boxes (1/2 X 0.04 second) = 0.18 second

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