Final answer:
A junctional rhythm arises when the AV junction discharges impulses faster than its normal rate. This can occur due to various factors that cause increased automaticity, leading to a potential arrhythmia or the need for an artificial pacemaker installation.
Step-by-step explanation:
A rhythm that has increased automaticity in the AV junction, causing the junction to discharge impulses at a rate faster than its intrinsic rate, is referred to as a junctional rhythm. Normally, pacemaker cells in the sinoatrial (SA) node establish a sinus rhythm by generating electrical signals. These signals travel through the heart leading to contraction. The SA node sets the inherent pace without extrinsic influences at 80-100 times per minute.
Comparatively, the atrioventricular (AV) node usually fires at 40-60 beats per minute when the SA node is not functioning. However, certain factors like ischemia, drugs, or disease can stimulate other cardiac cells, creating an ectopic focus that can discharge faster than the intrinsic rate, potentially leading to a junctional rhythm or arrhythmia.
When this enhanced automaticity becomes chronic, an artificial pacemaker may be implanted by a cardiologist to regulate the heart's rhythm. This device allows for consistent, controlled pacing, ensuring the heart contracts properly to maintain effective blood circulation.