Third Degree Heart Block ECG Interpretation with Sample Strip
ECG Strip
Third Degree Heart Block Rhythm Strip Features
Rate: Characterized by Atrial rate usually normal and faster than ventricular rateRhythm: Regular, but atrial and ventricular rhythms are independent
P Wave: Normal shape and size, may appear within QRS complexes
PR Interval: Absent: the atria and ventricles beat independently.
QRS: Normal, but wide if junctional escape focus
Complete heart block presents with Regular P to P and R to R intervals and a variable P-R interval.
In third degree heart block, none of the SA node impulses reach the ventricles. The ventricles will typically compensate by their own pacemaking, known as an escape rhythm. Thus, the atria and ventricles will beat independently and this can be observed on the ECG. The P waves (atrial beating) and QRS complex (ventricles) are unrelated in time. The PR interval will be variable.
External Source:
Authors and Sources
Authors and Reviewers
- ECG heart rhythm modules: Thomas O'Brien.
- ECG monitor simulation developer: Steve Collmann
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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
Sources
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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
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ECG Reference Guide
PracticalClinicalSkills.com
