Atrioventricular blocks can be classified into which types?

The classification of atrioventricular (AV) blocks is primarily determined by the degree of conduction disruption between the atria and the ventricles. The correct classification includes first-degree, second-degree, and third-degree AV blocks.

First-degree AV block features a prolonged PR interval with every atrial impulse conducted to the ventricles, indicating a delay but not a complete block. In second-degree AV block, there is a partial failure of conduction from the atria to the ventricles, which can be further subdivided into Mobitz type I (Wenckebach) and Mobitz type II, based on the patterns of dropped beats. Third-degree AV block, or complete heart block, is characterized by a complete dissociation between atrial and ventricular activity; the atria and ventricles beat independently of each other, which can lead to significant hemodynamic instability.

The other classifications mentioned—acute, subacute, and chronic; Class I, II, and III; and stable and unstable—do not specifically apply to AV block classifications in a way that recognizes the physiological nature of conduction disturbances. Thus, the classification into first, second, and third degrees provides a relevant and direct understanding of the condition and is essential for guiding treatment and management