Which degree of AV block is considered potentially dangerous?

• A. 1st degree
• B. 2nd degree type 1
• C. 2nd degree type 2
• D. 3rd degree

Answer: (C)

The potentially dangerous degree of AV block is the third degree. In third-degree AV block, there is a complete dissociation between atrial and ventricular activity. This means that the signals from the atria do not reach the ventricles at all, leading to inefficient heart rhythm and significantly reduced cardiac output. The heart rate can drop dangerously low, and patients may experience symptoms such as dizziness, fainting, or even cardiac arrest.

This condition often requires immediate medical intervention, such as the placement of a permanent pacemaker, to restore normal heart function. In contrast, while second-degree type 2 AV block can also be serious, it does not consistently result in complete dissociation like third degree, making it less immediately dangerous. Understanding the severity and potential consequences of each type of block is crucial for effective patient assessment and management in clinical settings.