Professional and Linguistic Assessments Board (PLAB) Practice Exam

Atrial Flutter is characterized by which type of heart rhythm?

1. Irregularly irregular rhythm

2. Regularly irregular rhythm

3. Regular rhythm

4. Sinus rhythm

The correct answer is: Regularly irregular rhythm

Atrial flutter is characterized by a regularly irregular rhythm. This condition results from reentrant circuits within the atria, leading to rapid atrial depolarization. The result is a distinctive pattern observed on an electrocardiogram (ECG), where there is a consistent and rapid series of 'F-waves' that appear as sawtooth flutter waves, particularly in the inferior leads. Unlike a sinus rhythm, which has a regular and steady pattern controlled by the sinus node, atrial flutter produces a more organized rhythm that still displays an irregularity in the ventricular response due to varying block patterns in the atrioventricular (AV) node. This is different from an irregularly irregular rhythm seen in conditions like atrial fibrillation, where there is no discernible organized pattern to the heartbeats. In atrial flutter, despite the irregularity of the ventricular response, the rhythm of the atria themselves remains regular, which distinguishes it from other arrhythmias.