Premature Atrial Complex - Atrial Rhythms
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
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
Analyze this tracing using the five steps of rhythm analysis.
- 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
- ECG heart rhythm modules: Thomas O'Brien.
- ECG monitor simulation developer: Steve Collmann
12 Lead Course: Dr. Michael Mazzini, MD.
- Spanish language ECG: Breena R. Taira, MD, MPH
- Medical review: Dr. Jonathan Keroes, MD
- Medical review: Dr. Pedro Azevedo, MD, Cardiology
- Last Update: 11/8/2021
Electrocardiography for Healthcare Professionals, 5th Edition
Kathryn Booth and Thomas O'Brien
ISBN10: 1260064778, ISBN13: 9781260064773
McGraw Hill, 2019
Rapid Interpretation of EKG's, Sixth Edition
Cover Publishing Company
12 Lead EKG for Nurses: Simple Steps to Interpret Rhythms, Arrhythmias, Blocks, Hypertrophy, Infarcts, & Cardiac Drugs
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