Second Degree Heart Block Type I - Course # 316-5
- Also known as Wenckebach Phenomenon; this dysrhythmia is typically stable and often temporary with the patient remaining asymptomatic as long as the ventricular response remains within the “normal” range.
- The unique feature (hallmark) of this dysrhythmia is the presence of a prolonging P-R interval from one cardiac complex to the next, until it reaches a point where the QRS complex is non-conducted ( blocked or more simply missing). Then the pattern starts over again.
- In this dysrhythmia, if the third QRS complex is dropped/blocked, then it will always be the third complex that is blocked before re-setting in a repetitious pattern.
- It is important to note the following:
- The P – P intervals are regular and the R to R intervals are irregular.
- here are more P waves than QRS complexes. Report the rate of each separately.
- Analyze this tracing using the five steps of rhythm analysis.
Compare your answers with the answers on the next slide.
- Rhythm: Atria – Regular, Ventricles - Irregular
- Rate: Atria – 56, Ventricles - 40
- P Wave: Upright
- PR interval: Variable, progressive
- QRS: 0.10 sec
- Interpretation: Second Degree Heart Block Type I
316 Second Degree Heart Block Type I - Course # 316-5