Second Degree Heart Block Type II - Heart Blocks.
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Description
- The hallmark of this dysrhythmia is a constant P-R interval with missing QRS complexes.
- This dysrhythmia may present in a couple of different ways.
- A. QRS complexes occurring in a specific pattern in a ratio with the P waves. This is often referred to as 2:1 or 3:1 block depending upon the ratio of P waves to each QRS complex.
- B. QRS complexes occur in a more unstable, unpredictable manner.
- Either presentation requires immediate reporting due to its potential for conversion to Third Degree (Complete) Heart Block.

B.

Practice Strip

Analyze this tracing using the five steps of rhythm analysis.
Show Answer
- Rhythm: Atria and Ventricles - Regular
- Rate: Atria – 125, Ventricles - 41
- P Wave: Upright
- PR interval: 0.14 sec
- QRS: 0.06
- Interpretation: Second Degree Heart Block Type II, 3:1
Practice Strip #2

Analyze this tracing using the five steps of rhythm analysis.
Show Answer
- Rhythm: A – Regular, V - Irregular
- Rate: Atria – 68, Ventricles - 40
- P Wave: Upright
- PR interval: 0.16 sec
- QRS: 0.08
- Interpretation: Second Degree Heart Block Type II
Authors and Reviewers
Authored by Thomas O'BrienMedically reviewed by Dr. Jonathan Keroes, MD, Cardiology
Last Update: 11/8/2020