A reentry phenomenon

Image 1

Came in due to CP. trop neg x3, pro-BNP-~ 10000, echo EF ~55, no WMA. Asymptomatic during at the time these ecg changes were noted. What do you think is happening here? 

Image 2 -ladder diagram

The tracing started as a sinus rhythm at about 70's bpm. After a PVC, retrograde P waves can be seen which can be seen distorting the ST segment. This created a short RP/long PR complex. The ladder diagram shown illustrates that as the impulse from the PVC was retrogradely conducted, it found the slow pathway in the AV node able to conduct (long PRI).  That same impulse later found the fast pathway able to conduct retrogradely. So, it created it the short RP. It then continued a few cycles. This arrhythmia was terminated by PVC's.

Image 3 - dual AV node physiology

This case illustrates dual AV node physiology (Image 3). In some persons, the AV node has 2 conducting pathways. One pathway is able to conduct fast and the other one is able to conduct slow. The fast pathway recovers slow (long refractory period) and the slow pathway recovers fast or short refractory period. These pathway can also conduct impulse retrogradely or in reverse direction. 

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