What is indicated by a rhythm with no P wave and a sawtooth motion before QRS complexes?

The presence of a rhythm characterized by no visible P waves alongside a distinct sawtooth pattern before the QRS complexes is indicative of atrial flutter. In atrial flutter, the atria contract in a rapid and coordinated manner, typically producing a "sawtooth" appearance, often referred to as "F-waves." This pattern can be particularly prominent in leads II, III, and aVF on an electrocardiogram (ECG).

This phenomenon occurs because the electrical signals in the atria circulate in a reentrant fashion, leading to a rapid and regular atrial rate while the ventricular response can vary depending on the conduction through the AV node. The absence of distinct P waves, which represent atrial depolarization, further supports the diagnosis, as in atrial flutter, the concerted activity of the atria is reflected in those sawtooth waves rather than separate P waves.

Understanding this characteristic helps differentiate atrial flutter from other arrhythmias, as conditions like atrial fibrillation would show chaotic atrial activity with no organized waveforms, while junctional rhythm would typically have a visible QRS complex with absent or retrograde P waves. In contrast, supraventricular tachycardia (SVT) presents