Cardiology In Critical Care
Arrhythmia Recognition
Junctional Premature Beats (JPB)
The impulse prematurely discharged from an irritable focus in or near the AV junction
spreads backward (retrograde) to the atria and forward (antegrade) to the ventricles.  An
inverted P wave may precede QRS by less than 0.12 sec ("upper" junctional beat ) or
inverted P wave may follow QRS ("lower" junctional beat) or P wave may be buried in
QRS ("middle" junctional beat).  Premature QRS is less than 0.22 sec but often slightly
distorted; occasionally QRS is wide and has RBBB configuration due to aberrancy.  The
pause following JPB is noncompensatory as explained for APB.

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