Premature Atrial Complex - Atrial Dysrhythmias.
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Intro to PAC
- PAC's 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.
- PAC's occur when an early electrical impulse occurs from a location in the atria other than the SA node.
Intro to PAC 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.
- PAC's can occur occasionally or frequently.
- PAC's 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.
EKG 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 PAC's
Authors and ReviewersAuthored by Thomas O'Brien
Medically reviewed by Dr. Jonathan Keroes, MD, Cardiology
Last Update: 11/8/2020