Bundle Branch Block EKG Interpretation | EKG.Academy
Your online EKG class
Complete Bundle Branch Block
Tech Series
ECG Interpretation
Thomas E. O'Brien
AS CCT CRAT RMA
Objectives
Upon completion of the accompanying narrative, the student will be able to:
- Recall which view is most commonly referred to when determining the presence of left or right bundle branch block
- Recognize the morphologic features and inclusion criteria of complete left or right bundle branch block
- Apply the process for measurement to determine the presence of left or right complete bundle branch block
Analysis of ECGs
People may choose to analyze ECG’s in a number of different ways. The sequence doesn’t necessarily matter as long as you gather and report the proper information each time.
If your protocols are different, always follow them.
Lessons
Lesson #1: Bundle Branch Block Determination
Intro
Evidence of Bundle branch block (BBB) may be seen in any lead, but the best view for determining the difference between left and right BBB is lead V1.
Interruption, delay of conduction or a change in the electrical conduction pathway will cause morphologic changes in the QRS complex.
Among those changes seen will include a widening of the QRS complex measuring 0.12 seconds or greater and may include an alteration in the deflection of the ventricular depolarization.
Lesson #2: Bundle Branch Block Determination II
Steps 1-3
Changes specifically seen include the QRS complex measuring 0.12 seconds or greater due to this delay. When determining the presence of BBB there are just a few simple steps to follow.
- Step 1: Refer to lead V1
- Step 2: Look for evidence that the electrical activity started above the ventricles (P wave). This is sometimes referred to as supraventricular activity.
- Step 3: QRS complex measures 0.12 seconds or greater (not including aberrant complexes i.e. PVCs)
Steps 1-3 (continued)
By following the previous three steps, you will be able to determine whether a BBB is present or not.
Now it is simply a matter of one more step when analyzing the QRS in V1 to distinguish whether it is a left BBB or a right BBB.
Lesson #3: Bundle Branch Block Determination III
Step 4
Analyze the terminal portion of the QRS complex. Starting at the “J” point go one small box back into the QRS (moving to the left).
- If the energy is below the isoelectric line, this is a left BBB.
- If the energy of the depolarization is above the isoelectric line, this is a right BBB.
- some people refer to a turn signal: down is left, up is right
Lesson #4: Quick Check 1-3
Question #1
Identify the branch bundle block.
Left BBB
Correct!Right BBB
Incorrect.Not BBB
Incorrect.Question #2
Identify the branch bundle block.
Left BBB
Correct!Right BBB
Incorrect.Not BBB
Incorrect.Question #3
Identify the branch bundle block.
Left BBB
Incorrect.Right BBB
Correct!Not BBB
Incorrect.Lesson #5: Quick Check 4-6
Question #4
Identify the branch bundle block.
Left BBB
Correct!Right BBB
Incorrect.Not BBB
Incorrect.Question #5
Identify the branch bundle block.
Left BBB
Incorrect.Right BBB
Correct!Not BBB
Incorrect.Question #6
Identify the branch bundle block.
Left BBB
Incorrect.Right BBB
Correct!Not BBB
Incorrect.Lesson #6: Quick Check 7-8
Question #7
Identify the branch bundle block.
Left BBB
Correct!Right BBB
Incorrect."Not BBB
Incorrect.Question #8
Identify the branch bundle block.
Left BBB
Incorrect.Right BBB
Correct!Not BBB
Incorrect.Return to Main Lessons Page
Authors and Reviewers
- EKG heart rhythm modules: Thomas O'Brien.
- EKG monitor simulation developer: Steve Collmann
-
12 Lead Course: Dr. Michael Mazzini, MD.
- Spanish language EKG: Breena R. Taira, MD, MPH
- Medical review: Dr. Jonathan Keroes, MD
- Medical review: Dr. Pedro Azevedo, MD, Cardiology
- Last Update: 11/8/2021
Sources
-
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
Dale Dublin
Cover Publishing Company -
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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