The correct answer is 0.12 – 0.20 seconds.
The duration of the delay in the AV node is 0.12 – 0.20 sec. The AV node contains specialized cells located on the right side of the atrial septum. It helps regulate the contraction of the atria and the ventricles AV node delay is a very significant delay in the cardiac cycle. It represents the delay in the conduction of velocity to the ventricles. This ensures that the atria have ejected the blood into the ventricles first before the ventricles begin to contract. This is to prevent the ventricles from contracting at a fast rate.
On ECG, AV node delay is denoted as “PR interval.” First-degree heart block is seen on ECG as an increased PR interval. In second degree AV block, some impulses do not get to the ventricles, and some PR intervals are missing on the ECG readings. In the third degree block, the impulses are blocked from reaching the ventricles.