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Step 5 QRS Complex - Cardiac Rhythms


  • 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.
analysis ecg image 117

Description 2

  • 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
how to measure qrs interval image 118

QRS Measurement 1

analysis ecg image 119

Analyze this tracing. What is the QRS duration?

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

QRS Measurement 2

measuing qrs interval image 120

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

Authors and Reviewers


? v:3 | cc: | tar: False | onAr:0 | onPs:2 | tLb:3 | tLbJs:0
| pv: 1 uStat: False | db:0 | shouldInvoke:False | pu:False | em: | refreshTime: 1/1/0001 12:00:00 AM || now: 7/13/2024 6:49:27 PM | firstPage: True
| statusStg: | cDbLookup# 0

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