What condition is indicated by a delay of impulse in the AV Node?

• A. Second-degree heart block
• B. Complete Heart Block
• C. First-degree heart block
• D. Sinus tachycardia

Answer: (C)

The condition indicated by a delay of impulse in the AV node is first-degree heart block. In this type of block, there is a prolonged PR interval on the electrocardiogram (ECG), which reflects a slower conduction of electrical impulses through the heart's AV node. This means that while all impulses are still conducted from the atria to the ventricles, the delay in conduction causes a longer time for that impulse to cross the AV junction.

First-degree heart block typically does not lead to any significant symptoms or hemodynamic compromise and is often considered a benign finding. The primary characteristic is the consistent elongation of the PR interval beyond 200 milliseconds, signaling that while impulses are being conducted, they are doing so more slowly than normal.

In contrast, conditions like second-degree heart block and complete heart block represent more significant degrees of impairment in impulse conduction, where not all impulses are transmitted to the ventricles, leading to more severe clinical implications. Sinus tachycardia indicates an increased heart rate but does not relate to AV nodal delay.