What is a junctional rhythm?

As a cardiac electrophysiologist, I specialize in the study and treatment of heart rhythm disorders. When discussing heart rhythms, it's important to understand the various types and their implications for a patient's health. A junctional rhythm is a type of cardiac rhythm that originates from the region of the atrioventricular (AV) node, which is located in the lower part of the heart's atria and is part of the heart's electrical conduction system. Normally, the heart's rhythm is initiated by the sinoatrial (SA) node, which is the heart's natural pacemaker. However, in certain conditions, the AV node can take over the role of initiating the heartbeat. In a junctional rhythm, the electrical impulses start near or within the atrioventricular node and then travel through the normal ventricular conduction system, which includes the bundle of His and the Purkinje fibers. Because this system is designed to efficiently conduct electrical impulses to the ventricles, the resulting QRS complex on an electrocardiogram (ECG) is often narrow, indicating that the ventricles are being activated in a coordinated manner. Junctional rhythms can occur in various clinical scenarios, such as in the presence of heart block, digitalis toxicity, or other conditions that affect the heart's electrical activity. It's crucial for healthcare providers to recognize and understand the underlying causes to provide appropriate treatment.

A junctional rhythm occurs when the electrical activation of the heart originates near or within the atrioventricular node, rather than from the sinoatrial node. Because the normal ventricular conduction system (His-Purkinje) is used, the QRS complex is frequently narrow.