Junctional rhythm Junctional rhythm Junctional rhythm describes an abnormal heart rhythm resulting from impulses coming from a locus of tissue in the area of the atrioventricular node, the "junction" between atria and ventricles. Under normal conditions, the heart's sinoatrial node determines the rate by which the organ beats – in other words, it is the heart's "pacemaker". The electrical activity of sinus rhythm originates in the sinoatrial node and depolarizes the atria. Current then passes from the atria through the atrioventricular node and into the bundle of His, from which it travels along Purkinje fibers to reach and depolarize the ventricles. This
Sinoatrial block block looks very similar to a sinus arrest. However, a sinus arrest is caused by a failure to form impulses. A third degree block is caused by failure to conduct them. The rhythm is irregular and either normal or slow. It is followed by a long pause that is not a multiple of the P-R interval. The pause ends with a P wave, instead of a junctional escape beat the way a sinus arrest would. Emergency treatment consists of administration of atropine sulfate or transcutaneous pacing. Sinoatrial block A sinoatrial block is a disorder in the normal rhythm of the