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.
As in other SVTs, the QRS in atrial flutter is narrow unless aberrancy or BBB is present. When you encounter SVTs in the range of 150 bpm, try to rule out flutter first by looking at the rhythm in multiple leads for visible flutter waves. The patient's response to carotid sinus massage may also help in identifying the rhythm. Because the reentry circuit is located within the right atrium, not the AV node, carotid sinus massage won't convert this arrhythmia. This maneuver should be performed only by a physician in a monitored setting.