This ECG is from a male, and that's all I've got.
|Click to enlarge|
- Ventricular Rate 60 bpm
- Atrial rate 90 bpm
- Regular rhythm
- Regular atrial activity
- P wave -> QRS -> P wave -> Pause -> Paced Complex + Buried P wave
- Sinus Complexes - LAD (-37 deg)
- Paced Complexes - LAD (-80 deg)
- PR - Normal (~180ms)
- QRS - Prolonged (120ms)
- QT - 440ms
- QRS - Prolonged (160ms)
- QT - 520ms
- Appropriate ST segment & T wave discordant changes in both Sinus & Paced Complexes
- LBBB Morphology of Sinus Complexes
- Right Ventricle Pacing
- Paced Complexes have LBBB Morphology
- Pacing Interval 60 bpm from Conducted QRS
- If no QRS sensed 1000ms after last QRS PM will pace
- Unknown if P wave following sinus QRS would have conducted with long PR or would have blocked
- P waves hidden in ST segment of Paced Complexes
- Unlikely to be retrograde conduction
- Likely Atrial Rate is Isorhythmic to Pacing in 3:1 Pattern
- High Grade AV Block with Escape Ventricular Pacing
VVI vs DDD ?
Christopher raised the question if you can tell whether this PPM is DDD or VVI from this ECG.
Dr Arieh Keren, has kindly come to the rescue. and gives us a brief explanation of pacing modes and their ECG morphology.
"The PM is VVI. A DDD pacemaker will be pacing the atrium if the sinus rate is below the lower rate limit only. Usually if the sinus rate is normal or above the lower rate, the way you know it's a DDD, is that you have every P wave followed by a paced QRS (A sense V pace) or a conducted QRS with a max set PR interval. (not common).
If there is a pattern to the P wave association with the QRS and it is not timing off a conducted beat like in this case, it must be dual chamber otherwise the PM can not coordinate an association."
Why is the PR Interval Normal for Sinus Complexes ?
We know we have significant conduction system disease present in this case, and yet the PR segment is normal for the conducted QRS complexes, why ?
There are essentially two non-conducted P waves preceding every conducted QRS, this allows time for AVN & HIS systems to recover
Many thanks to all our commenter's for sharing their thoughts and raising some interesting questions. Also thanks to Dr Arieh Keren, from our blogging team, for his thoughts and explanations on this ECG.
Life in the Fast Lane
- 2nd Degree AV Block
- Paced Rhythms here
- Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.