Can you guess what is in these photos? Attached are two electrograms for the first installment of this special monthly feature. Send us your responses — we will publish the answer in next month’s issue!

Description:
“These recordings were obtained at the first clinic visit for this post-pacemaker- implant patient. The patient had been feeling increased fatigue in the last week.”

Questions:

1. What is the rhythm?
2. What is occuring with the atrial electrogram?