Here is the link to what WiKiPedia has to say about A-Fib which is way more than I wanted to copy and paste.
http://en.wikipedia.org/wiki/Atrial_fibrillation
Basically it is an Irregular Heart Beat, often rapid, but not always.
Many patients get A-Fib after OHS. It can come and go or be continuous.
It may come and go for several weeks after OHS.
It may or may not respond to 'lesser drugs'.
It may clear up on it's own after 'running it's course'.
It can make you feel 'weak and tired'.
It can cause Blood Clots to form.
A-Fib patients are usually prescribed to be on Coumadin / Warfarin (anti-coagulents) to minimize the risk of clot formation.
Common Triggers are Stress, Caffeine (Coffee, Tea, Cola Drinks, Chocolate, etc.), Nicotine, other non-Rx drugs, etc.
It can be diagnosed with an EKG (i.e. if it happens while you are in the Hospital, a Nurse will see it immediately on their monitor).
If you have been diagnosed with A-Fib and no other arrhythmias, you can 'probably' self diagnose with a stethoscope if you hear a similar pattern.
There are several drugs that can help control / prevent A-Fib. Several members have had good results with Sotalol (the generic form of BetaPace). Too many Doctors simply prescribe Amiodarone which is the Sledge Hammer of antiarrhythmics "because it works and they can send patients home sooner". High Doses or taking for too long can result in some Nasty Side Effects. (Do a Search for Amiodarone or Google or get an informatiion sheet from your Pharmacist to learn the gory details). As you can tell, I am not a fan of using Amiodarone for A-Fib unless Nothing Else Works.
'AL Capshaw'