This is a good example of atrial flutter with variable conduction in a 53-year-old man. He had been treated for a fast rate, and now has a rate of approximately 90 per minute. No other clinical information is available. One of the good teaching points in this ECG is that some leads show P waves (or, in this case, flutter waves) better than others. The diagnosis of atrial flutter can be missed by practitioners utilizing only one or two leads.
The typical flutter waves, at a rate close to 300 / min., can best be seen in Leads II, III, aVF, aVL, V1, and V3. Leads II and aVF are especially good for teaching students to "march out" the flutter waves through the entire strip. They can be seen in the QRS complexes and T waves in these leads.
Because atrial flutter often accompanies a diagnosis of congestive heart failure, this is a good ECG for teaching the contribution of rate - atrial and ventricular - in the workload and cardiac output of the patient.