What Is First-Degree AV Block?
First-degree atrioventricular (AV) block is a variation in the normal rhythm of the heart where the electrical signal between the atria and ventricles is slightly delayed. This condition usually does not cause any symptoms, and may be an incidental finding during a routine examination for an unrelated medical problem. Treatment is generally not required unless there are concerns that the first-degree AV block may progress into a more serious heart block, which can be an issue if a patient has an underlying medical problem. In a patient with first-degree AV block, the PR interval, which is the amount of time needed for a signal to travel from the atria to the ventricles, is greater than 0.2 seconds. In healthy individuals, this interval is smaller than 0.2 seconds. The PR interval can be clearly seen on an electrocardiograph, allowing a doctor to diagnose the patient with first-degree AV block.
