Atrial Fibrillation is an arrhythmia that begins in the atria. The electrical impulse that normally originates in the SA node becomes overridden by chaotic signals; the atria beat much faster and in a disorganized manner which reduces the pumping efficiency of the heart.
Atrial fibrillation is the most common sustained cardiac arrhythmia. It affects an estimated 2.66 million Americans right now and is expected to become even more prevalent, affecting as many as 12 million by the year 2050 (Lloyd-Jones et al., 2010). It goes largely unrecognized – nearly 70% of patients do not know they have Atrial Fibrillation until it is discovered when they present to a hospital. (Psaty et al., 1997)
This EKG rhythm strip demonstrates atrial fibrillation. It is an irregular rhythm with fibrillatory atrial activity. As you can see, there are no regular P waves and the baseline is uneven. The ventricular response (when you feel for your pulse) may be slow (<60 beats per minute), normal (60-100 beats per minute), or rapid (more than 100 beats per minute).