Reciprocal Beating in a Paced Rhythm

This is :

 

Figure 1

a. bidirectional PVC

b. Ventricular pacing with reciprocal beats

c. Ventricular pacing with PVC in bigeminy

 Reciprocal beating induced by ventricular pacing

 

Figure 2 (ladder diagram)

The first wide QRS beat is a ventricular-paced beat (VP) . Tiny pacer spikes are best seen in long lead II. A retrograde P (P') wave is seen after the ventricular paced beat at an RP interval of about 260 ms. A wide QRS beat (reciprocal beat or echo beat or Re) then follows P' with a PR interval of about 200 ms. The reciprocal beat is followed by another retrogradely conducted P wave (P") with an RP interval of about 360 ms. After 840 ms from the reciprocal beat (Re) or about 70 bpm, a pacer spike can be seen.

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