First Degree Heart Block - Heart Blocks.
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- First Degree Heart Block will look like a typical sinus rhythm with one distinguishing feature.
- The P-R interval will be constant throughout the tracing and measure greater than 0.20 seconds.
- Rate, regularity, P wave morphology and QRS duration and morphology will be unaffected.
- NOTE: The rate will be that of the underlying rhythm. If the rate is “normal”, it will be 60 – 100 bpm. If it is bradycardia, the rate will be less than 60 bpm.
- First Degree Heart Block is the most common heart block.
- People are born with it every day. They will likely live a long and healthy life and die from some other malady.
- Patients who develop a heart block during an MI bear close observation. This must be reported to the licensed healthcare practitioner immediately.
Notice the following: the only abnormality when analyzing this tracing is the abnormal duration of the P-R interval.
Analyze this tracing using the five steps of rhythm analysis.
- Rhythm: Regular
- Rate: 68
- P Wave: Upright
- PR interval: 0.28 sec
- QRS: 0.08 sec
- Interpretation: First Degree Heart Block
Authors and ReviewersAuthored by Thomas O'Brien
Medically reviewed by Dr. Jonathan Keroes, MD, Cardiology
Last Update: 11/8/2020