What defines a junctional rhythm?

A junctional rhythm is defined by its origin from the atrioventricular (AV) junction, which is the area between the atria and the ventricles. This rhythm typically presents with absent P waves or P waves that are inverted, reflecting the fact that depolarization is occurring from the junction rather than the sinus node in the atria, which usually produces upright P waves.

In the context of cardiac physiology, when the AV node takes over pacing the heart—usually due to a failure of the sinoatrial (SA) node—this rhythm can occur. The heart rate in junctional rhythms is generally between 40 and 60 beats per minute unless the junctional escape rhythm accelerates or there are junctional beats occurring at different rates. The characteristics of the P waves being absent or inverted is crucial in differentiating junctional rhythms from other types of arrhythmias.

Other choices do not accurately describe a junctional rhythm: rhythms characterized by prominent P waves typically suggest atrial activity (not junctional). Atrial flutter is characterized by a rapid atrial rate and sawtooth P waves rather than junctional features. A prolonged QT interval often corresponds to various forms of ventricular dysrhythmias and does not relate to the