Junctional rhythm

Blurb: Slow, Regular but P wave retrograde, inverted, or absent, QRS normal width. Watch for symptoms. Treat the cause such as SA blocking med or electrolyte disturbances. May need pacemaker (SA node not working)

I - Recognize:
1 - Rate:
   a - Usually slow: <60bpm (due to rhythm originates from below SA node but still in AV node)
   b - If faster (>60bpm), is called accelerated junctional rhythm

2 - Rhythm: REGULAR meaning every beat morphology is similar to each other.



3 - Axis: skip this for now


4 - Width:

P wave width: normal
. retrograde = before QRS complex, absent = buried in QRS complex, or late = behind QRS complex
Explanation:  Since the electrical activation originates at or near the AV node, the P wave frequently is not seen. It can be buried within the QRS complex, slightly before the QRS complex or slightly after the QRS complex.


QRS complex width: normal
A junctional rhythm occurs when the electrical activation of the heart originates near or within the AV node instead of from the SA node. Since the normal ventricular conduction system (His-Purkinje) is used, the QRS complex is frequently narrow. 


5 - Height:
P wave height: upside down usu.
. inverted = P wave (atrial contraction) is activated from below. 
The morphology of the P wave will not be similar to the sinus P wave (which is normally upright in lead II and biphasic in lead V1). Frequently, the P wave is inverted in lead II if it can be seen at all.

II - Treat:
. Watchful waiting
. Figure out the cause: SA blocking medications/electrolytes disturbances.
. Finally, may need pacemaker to relieve symptoms

 Explanation: A pacemaker may be needed to relieve symptoms when no reversible cause is found such as SA blocking medications or electrolyte disturbances.



See more at/Sources:
http://www.healio.com/cardiology/learn-the-heart/ecg-review/ecg-topic-reviews-and-criteria/junctional-rhythms-review