Which of these is NOT a junctional rhythm?

The correct answer, which identifies which option is NOT a junctional rhythm, is indeed Atrial flutter. A junctional rhythm originates from the area around the atrioventricular (AV) node, where the electrical impulses can arise due to various reasons.

Junctional tachycardia, accelerated junctional rhythm, and premature junctional contraction all derive from the junctional area. Junctional tachycardia is characterized by a rapid heart rate that originates from this junction, while accelerated junctional rhythm refers to rhythms that are faster than the normal junctional rhythm but still arise from the same area. A premature junctional contraction occurs when an impulse from the junction occurs earlier than expected, interrupting the regular pacing from the sinus node.

In contrast, atrial flutter is a distinct arrhythmia that originates from the atrial tissue, specifically involving reentrant circuits within the atria that create a rapid and regular atrial rate. This fundamentally differs from junctional rhythms because it is not dependent on the AV node for its rhythm generation. Atrial flutter exhibits specific characteristics such as "sawtooth" patterns on an EKG, which are not present in junctional rhythms.

Thus, identifying atrial flutter as not being a junction