What characterizes a junctional rhythm?

A junctional rhythm is characterized by its origin from the atrioventricular (AV) junction, which is the area of the heart where the atria and ventricles meet. This rhythm typically occurs when the impulse originates from the AV node or surrounding tissues, leading to an electrical signal that may not engage the atria in the usual way. The presence of inverted P waves is a common feature, as these waves can occur before the QRS complex, after the QRS complex, or may even be absent altogether, but when present, they are often inverted due to the retrograde atrial activation.

The regularity of the rhythm and the specific characteristics of the P waves differentiates junctional rhythms from other types, such as atrial rhythms or ventricular rhythms. Junctional rhythms also have a specific heart rate that may be slower than traditional sinus rhythms, generally ranging from 40 to 60 beats per minute but can fall to as low as 20 to 40 bpm, indicating possible escape rhythms. This relationship between the frequency of the rhythm and the inverted nature of P waves highlights how junctional rhythms distinctly operate in the conduction system of the heart.