Certified Rhythm Analysis Technician (CRAT) Practice Exam 2025 – All-in-One Study Guide for Exam Success!

The rhythm characterized by regular P-P and R-R intervals occurring at different rates is complete heart block, also known as third-degree AV block. In this condition, the electrical signals from the atria (which generate the P waves) and the ventricles (which generate the R waves) are completely dissociated. As a result, the atria and ventricles contract independently of each other.

In complete heart block, the P waves occur at a regular rate, typically determined by the activity of the atrial pacemaker. Meanwhile, the QRS complexes are also regular but occur at a rate determined by the junctional or ventricular escape rhythm, which is often slower than the atrial rate. This results in the P waves and R waves being regular but at different rates, which is a hallmark of complete heart block.

Other options, such as Wenckebach (Mobitz Type I), atrial fibrillation, and first-degree heart block, do not exhibit this specific characteristic. For instance, Wenckebach demonstrates progressively lengthening PR intervals before a dropped beat, which doesn't align with the regular P-P and R-R intervals seen in complete heart block. Atrial fibrillation features irregularly irregular P waves and R-R intervals making them inconsistent.