Advanced Cardiovascular Life Support (ACLS) Practice Exam

Which arrhythmia is characterized by a rapid reentry circuit in the atria?

1. Atrial flutter

2. Sinus bradycardia

3. Monomorphic ventricular tachycardia

4. Fine ventricular fibrillation

The correct answer is: Atrial flutter

Atrial flutter is characterized by a rapid reentry circuit in the atria that leads to a distinct and organized pattern of atrial electrical activity. In this arrhythmia, the reentry circuit typically revolves around a specific anatomical barrier, such as the tricuspid valve, creating a circuit that allows electrical impulses to travel rapidly, resulting in a characteristic "sawtooth" appearance on an electrocardiogram (ECG), known as "F-waves." The rapid atrial contractions during atrial flutter usually occur at a rate of 240 to 340 beats per minute, which can lead to variable ventricular responses depending on the conduction through the atrioventricular (AV) node. This organized rhythm contrasts with disorganized rhythms that characterize other arrhythmias, such as ventricular fibrillation or sinus bradycardia, where there is no reentry circuit in the atria. Understanding the mechanism of atrial flutter is crucial in ACLS as it informs treatment approaches, including potential anticoagulation to prevent thromboembolic complications, rate control strategies, and considerations for rhythm conversion.