Premature Atrial Complex | Reference Guide
EKG Features
Rate: Usually normal but depends on underlying rhythmRhythm: Irregular
P Wave: Premature, positive and shape is abnormal
PR Interval: Normal or longer
QRS: 0.10 sec or less
This early impulse causes an early cardiac complex which disrupts the underlying rhythm.
Premature atrial contractions are a common arrhythmia with early beats. PACs are caused by ectopic atrial sites firing an electrical signal before the next normal SA node fires. PACs can occur in healthy young and elderly patients. Premature atrial contractions are also called premature atrial complexes.
External Source: http://www.medicinenet.com/heart_rhythm_disorders/page2.htm
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EKG Tracing Example

Authors and Reviewers
Authored by Thomas O'BrienMedically reviewed by Dr. Jonathan Keroes, MD
Last Update: 11/8/2021