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| Click to enlarge |
- Mean ventricular rate 60 bpm
- Mean atrial rate ~78-84 bpm
- Irregular narrow complex ventricular rhythm
- Single PVC (QRS Complex #8)
- Atrial activity with variable rate
- Number of P waves are buried within the terminal QRS / T waves
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| P waves labelled Click to enlarge |
Axis:
- Normal
- QRS - Normal (80-100 ms)
- QT - 440 ms
- ST segment variability due to baseline wander and P wave super-imposition
Additional:
- P-P variability likely due to ventriculophasic arrhythmia
Interpretation:
- Complete heart block
- It could be 2:1 block but I think the P waves being buried before the T wave suggest complete heart block to be absolutely certain you'd need a longer rhythm strip
- Ventriculophasic Arrhythmia
What is ventriculophasic arrhythmia ?
This phenomenon can be seen in up 40% of case of complete AV block and, as in this case, can be seen with 2nd degree AV block also.
You get a shorter P-P interval when there is an associate QRS complex with a longer P-P when there is no QRS between the P waves. Several mechanisms have been proposed including alterations in sinus node perfusion related to ventricular contraction and the mechanical effects of atrial stretch.
To make things more confusing there is a much rarer paradoxical phenomenon when the P-P is longer when a QRS is contained between them.
It is important to recognized as the P-P variability may be mistaken for other ECG features such as U waves for example.
We've had a few case examples on our blog the best of which can be found here:
You can read more about ventriculophasic sinus arrhythmia in this nice case report of the paradoxical version here:
References / Further Reading
Life in the Fast Lane
Textbook
- Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.
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