Third Degree Heart Block - Course # 316-7
Description Part 1
- Third Degree Heart Block is also known as “Complete Heart Block”.
- This name more accurately describes the electrical event or problem occurring within the heart.
- As a result of disease or tissue death, there is a blockage preventing electrical impulses within the atria from entering the ventricular conduction system.
- The outcome of this impediment are two independently functioning pacemakers within the heart (typically one is supraventricular, the other is ventricular).
- Essentially, the atria and ventricles are electrically separated (dissociated) from one another.
Description Part 2
- What will be seen are regularly occurring P waves and QRS complexes, but at two distinctly different rates.
- The QRS complexes may occur as a result of impulses coming from the His bundle or the Purkinje network.
- Morphology and rate will often provide clues regarding the locus of ventricular impulse stimulation. A more narrow appearing QRS with a rate greater than 40 generally would indicate the impulse formation is coming from the His bundle. A wide, bizarre QRS with a rate of 40 or less indicates the impulses are originating in the Purkinje network.
- Complete heart block presents with Regular P to P and R to R intervals and a variable P-R interval.
- Analyze this tracing using the five steps of rhythm analysis.
- Compare your answers with the answers on the next slide.
- Rhythm: Atria and Ventricles - Regular
- Rate: Atria – 94, Ventricles - 34
- P Wave: Upright (some buried)
- PR interval: Variable
- QRS: 0.14 sec
- Interpretation: Third Degree (Complete) Heart Block
316 Third Degree Heart Block - Course # 316-7