Which finding is associated with a heart rate of greater than 350 bpm and saw-toothed P waves?

• A. Atrial flutter
• B. Paroxysmal supraventricular tachycardia
• C. Ventricular fibrillation
• D. Brief ventricular tachycardia

Answer: (A)

A heart rate of greater than 350 beats per minute combined with the presence of saw-toothed P waves is indicative of atrial flutter. Atrial flutter is characterized by rapid reentrant circuits in the atria that generate a specific pattern of electrical activity. The distinct saw-tooth shape of the P waves is often referred to as "F-waves" and is predominantly observed in the inferior leads of an electrocardiogram (ECG), primarily the II, III, and aVF leads.

Understanding the mechanics of atrial flutter helps explain why the rapid heart rate occurs; the atria are depolarizing at a high frequency due to a recurring electrical circuit, often resulting in a consistent ventricular response that can vary based on any underlying conduction system response to the atrial activity. This differentiates atrial flutter from other rapid heart rate conditions that do not display this particular P wave morphology.