Poll: What is this patient's cardiac rhythm?

27 y/o female patient presents with cough and runny nose for several days.  Vitals notable for HR of 150 but otherwise normal.  An EKG is obtained:

12 lead EKG.  Click pic to enlarge.

6 mg of adenosine given:

Multiple lead rhythm strip obtained while adenosine given.  Click pic to enlarge.

12 mg of adenosine given:

Multiple lead rhythm strip obtained while adenosine given.  Click pic to enlarge.

After each dose of adenosine patient reverted back to the rhythm, with associated rate, noted in the original EKG. What is the rhythm?


Answer to be posted Monday.