What condition is characterized by a complete heart block?

A complete heart block, also known as third-degree atrioventricular (AV) block, is characterized by a complete dissociation between atrial and ventricular activity. In this condition, the electrical signals from the atria do not conduct to the ventricles due to a failure at the AV node or within the His-Purkinje system. As a result, the atria and ventricles beat independently, leading to a situation where the heart's rhythm is not synchronized.

In third-degree AV block, the atrial rate continues normally, but the ventricles beat at a much slower rate, which is typically driven by a backup pacemaker within the ventricles. This results in significant bradycardia, which can lead to symptoms such as dizziness, fatigue, or even syncope. The complete inability of electric impulses to pass through to the ventricles is what distinctively marks this condition.

For reference, the other types of block—first-degree and second-degree AV blocks—do not exhibit this complete dissociation. First-degree AV block involves a prolonged PR interval, indicating a delay in conduction but no dropped beats. Second-degree AV block can further be classified into types (Mobitz type I and type II), where some beats are dropped but there