An electrocardiogram of a patient with atrial flutter typically shows which characteristic?

The characteristic feature of atrial flutter on an electrocardiogram (ECG) is the presence of a sawtooth pattern of P waves, often referred to as F-waves. This distinctive pattern is typically seen in the inferior leads (II, III, aVF) and indicates that atrial depolarization is occurring in a circular manner, which is typical in this type of arrhythmia. These F-waves create a "sawtooth" appearance, particularly in lead II, due to the reentrant nature of atrial flutter, where the electrical impulse repeatedly circulates in the atria.

The sawtooth appearance helps differentiate atrial flutter from other rhythms, such as atrial fibrillation, which features irregularly shaped waveforms with no discernible organized pattern. Recognizing this specific pattern is vital for proper diagnosis and management of atrial flutter, as it can influence treatment strategies such as the choice of antiarrhythmic medications or the consideration of catheter ablation.