A consistent prolongation of the P-R interval beyond 0.

A consistent prolongation of the P-R interval beyond 0.20 seconds indicates a first-degree atrioventricular (AV) block. This type of block is characterized by a delay in the conduction of electrical impulses through the AV node, resulting in a prolonged P-R interval. However, every P wave is still followed by a QRS complex, distinguishing it from higher-degree AV blocks where some P waves are not followed by QRS complexes.References: = CCRN Exam Handbook, page 35