Which term describes the rhythm initiated by the junctional foci?

Which term describes the rhythm initiated by the junctional foci?

• A. Idiojunctional rhythm
• B. Atrial rhythm
• C. Ventricular rhythm
• D. Normal sinus rhythm

Answer: (A)

The term that accurately describes the rhythm initiated by the junctional foci is known as an idiojunctional rhythm. This occurs when the electrical impulses originate in the junctional tissues, located at the atrioventricular (AV) node area, which can happen when the sinus node fails to fire or is not effective.

In an idiojunctional rhythm, the heart rate is generally slower than normal (usually around 40-60 beats per minute) and characterized by the absence of P waves or the presence of inverted P waves, as these may occur after the QRS complexes due to retrograde conduction. This rhythm relies on the natural pacemaking ability of the junctional tissues, which take over when other higher pacemakers (like the sinus node) malfunction.

Understanding this rhythm is crucial for EKG interpretation as it helps differentiate junctional rhythms from other types, providing insight into potential underlying heart conditions. Atrial rhythms originate from the atrial foci, ventricular rhythms from the ventricles, and normal sinus rhythm originates from the sinus node, hence making them distinct from junctional origins.