ECG of the Week - 2nd December 2013

This week's ECG is from a 68yr old female who presents complaining of palpitations intermittently over the last 4 days with a concurrent viral upper respiratory tract infection. She has a history of paroxysmal atrial fibrillation and mitral valve replacement (St Jude's) and medications include warfarin and sotalol.

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Given that this week's ECG is a bit of a rhythm puzzler I've included a numbered rhythm strip version to aid in peoples written descriptions (I finally remembered Ken)

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VAQ Corner

A 68yr old female presents to your Emergency Department complaining of palpitations intermittently over the last 4 days with a concurrent viral upper respiratory tract infection. She has a history of paroxysmal atrial fibrillation and mitral valve replacement (St Jude's) and medications include warfarin and sotalol.
Vital signs: BP 124/76 RR 18 Sats 96% RA Temp 36.8

Describe & interpret her ECG ?