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Accelerated Junctional Rhythm example two



Notice that P-waves don't precede the QRS complexes, and look at the QRS
shape and duration.  There are rabbit ears in V with no positive deflections,
and the duration is 0.12 seconds, characteristic of a left bundle branch block.
This is a junctional rhythm, but the rate is 85 per minute.  This is much faster
than a typical junctional rhythm:  it is an accelerated junctional rhythm.
Note the bumps ending the QRS complexes in leads II, III and V: these may be
retrograde P-waves.  If the pacemaker is low in the AV node, retrograde
conduction to the atria is delayed as the impulse passes through the bulk of
the node, and thus the P-wave appears after the QRS.  Also note in leads II
and III that the T-wave is followed by a deflection called a U-wave.  This wave
is visible with hypokalemia or can be a quinidine effect.