What is the condition characterized by no conduction through the atrioventricular (AV) node?

The condition characterized by no conduction through the atrioventricular (AV) node is third-degree AV block, also known as complete heart block. In this situation, there is a complete dissociation between the atria and the ventricles. This means that impulses generated in the atria cannot reach the ventricles due to a failure of conduction through the AV node. As a result, the atria continue to contract independently, usually at their intrinsic rate, while the ventricles will also beat independently, often at a much slower rate, potentially leading to significant hemodynamic instability.

In contrast, first-degree AV block allows all atrial impulses to be conducted to the ventricles, albeit with a prolonged conduction time. Second-degree AV block also permits some atrial impulses to be conducted, but there is an intermittent failure of conduction, which results in some dropped beats. A bundle branch block is not a type of AV block but rather a specific conduction delay in the left or right bundle branches, affecting the ventricles, but does not involve the AV node directly.