Atrial Fibrillation
Atrial Fibrillation (AF) is defined as a cardiac arrhytmia with the following characteristics:
The surface ECG shows ‘absolutely’ irregular RR intervals, i.e. RR intervals that do not follow a repetitive pattern
There are no distict P waves on the surface ECG. Some apparently regular atrial electrical activity may be seen in some ECG leads, most often in lead V1
The atrial cycle length (when visible), i.e. the interval between two atrial activations, is usually variable and <200ms (>300 bpm)