Patient Care Technician (PCT) AAH Practice Exam

What is indicated by a PR interval longer than 0.2 seconds on an EKG?

1. 1st Degree Block

2. 2nd Degree Block

3. 3rd Degree Block

4. Normal sinus rhythm

The correct answer is: 1st Degree Block

A PR interval longer than 0.2 seconds on an EKG indicates a first-degree heart block. This condition is characterized by a delay in the conduction of electrical impulses through the atrioventricular (AV) node, which causes a prolonged PR interval. In a first-degree heart block, each atrial impulse still reaches the ventricles, but the delay increases. The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex, and when it exceeds the normal range (which is typically 0.12 to 0.20 seconds), it confirms that the conduction through the AV node is slowed. While second-degree and third-degree blocks involve more complex conduction issues, they typically present with additional symptoms such as dropped beats or complete loss of conductance to the ventricles, leading to more pronounced EKG changes. Identifying the length of the PR interval is crucial in diagnosing these conditions accurately, but a lengthened PR interval alone indicates a first-degree block. In a normal sinus rhythm, the PR interval falls within the normal range, usually between 0.12 and 0.20 seconds.