A young patient comes into your RESUS area complaining of palpitations, and you get handed this EKG. What do you do?

A fib with an accessory pathway can go so fast that it can be misdiagnosed as V tach/ SVT, however if misdiagnosed, the usual treatment could cause you to push the patient into v fib and even death!

Can reach rates of 250-300 as opposed to our usual bread and butter a fib with RVR

Avoid all AV nodal blockers if concerned that there may be an accessory pathway involved

From LITFL

Procainamide is your agent of choice

A great review of the pre-excitation syndromes

http://lifeinthefastlane.com/ecg-library/pre-excitation-syndromes/

EKG Guru Amal Mattu has a wonderful 20 min video on this topic that explains it really well

http://ekgumem.tumblr.com/post/104045855859/17-yom-with-palpitations-what-drugs-are