AEMCA Practice Exam

What is the intrinsic rate of the AV node?

1. 60-80 bpm

2. 40-60 bpm

3. 80-100 bpm

4. 20-40 bpm

The correct answer is: 40-60 bpm

The intrinsic rate of the atrioventricular (AV) node is indeed 40-60 beats per minute (bpm). This intrinsic pacing ability is significant for understanding how the heart's conduction system operates, especially in cases where the primary pacemaker, the sinoatrial (SA) node, fails or is compromised. The AV node acts as a backup pacemaker. When the SA node, which typically fires at a rate of 60-100 bpm, is not functioning correctly, the AV node can take over the pacing of the heart. However, the rate at which it can do this is lower, which is why the intrinsic rate is in the 40-60 bpm range. Understanding this helps in recognizing bradycardic arrhythmias that might result from AV nodal dominance. This rate range also differentiates the AV node from other cardiac structures, such as the SA node and bundle of His, which have their own intrinsic rates. Thus, the correct answer reflects fundamental electrophysiological knowledge regarding the heart's conduction system.