Don't give digoxin or verapamil if you suspect preexcitation. These drugs block conduction over the AV node, but not across the accessory path. If the patient stays in sinus rhythm, that's not a problem. The patient will then need immediate cardioversion. Typically unstable, atrial flutter tends to either revert to sinus rhythm or deteriorate to atrial fibrillation.
Atrial flutter is categorized into two types.
Type I, the common or classic type, has an atrial rate ranging from 250 to 350 bpm. Type II is characterized by a rate ranging from 350 to 450 bpm. On ECG, atrial flutter waves recur identically in a regular sawtooth pattern best visualized in leads II, III, aVF, and V 1 . Conduction to the ventricles varies. Varied conduction can also occur, producing an irregular R-R interval.