Which arrhythmia is characterized by a “sawtooth” appearance of the P waves?

The arrhythmia associated with a “sawtooth” appearance of the P waves is atrial flutter. This distinct pattern, often described as "F-waves," occurs due to a reentrant circuit typically located in the right atrium. During atrial flutter, the atria contract rapidly at rates usually between 240 to 340 beats per minute, leading to this characteristic sawtooth configuration.

Atrial flutter is particularly notable in its organized rhythm, contrasting sharply with atrial fibrillation, which features chaotic and irregularly timed P waves, lacking that distinct sawtooth structure. The regular pattern of atrial contractions in flutter can often be identified visually on an electrocardiogram (ECG), making this condition distinguishable to trained healthcare professionals.

In summary, the sawtooth appearance of the P waves is a hallmark sign of atrial flutter, facilitating its identification and management in clinical practice.