Premature Atrial Complex ECG Interpretation


Intro to PACs

  • PACs can occur for a number of different reasons i.e., diet, fatigue, stress, disease, ischemia to name a few.
  • Premature complexes frequently occur in bradycardic rhythms, but may occur almost any time.
  • PACs occur when an early electrical impulse occurs from a location in the atria other than the SA node.

Intro to PACs 2

  • This early impulse causes an early cardiac complex which disrupts the underlying rhythm.
  • The locus of stimulation being different, results in a change in the morphology of the P wave.
  • PACs can occur occasionally or frequently.
  • PACs ECG can be observed with or without a pattern
  • The P wave with PAC's will always be upright

ECG Analysis

pacs ecg image

Notice the following: the R to R interval is irregular, the fifth complex is early and the P wave on the early complex is a different shape.

ECG Practice Strip

atrial ecg image 2

Analyze this tracing using the five steps of rhythm analysis.

Show Answer
  • Rhythm: Irregular
  • Rate: 50
  • P wave: Upright & uniform (except early complexes - biphasic)
  • PR interval: 0.16 second
  • QRS: 0.08
  • Interpretation: Sinus Bradycardia with PACs





Authors and Sources

Authors and Reviewers


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






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