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

A bundle branch block occurs when one or both of the ventricular pathways—known as the right and left bundle branches—fail to conduct electrical impulses appropriately. This condition can arise due to damage from cardiac diseases, the effects of certain drugs, or other underlying health issues. When there is a blockage, the electrical activation of the ventricles becomes delayed or impaired, which can be observed on an electrocardiogram (ECG) as a widening of the QRS complex.

The significance of recognizing a bundle branch block lies in its impact on the heart's function; it can lead to ineffective ventricular contraction and may indicate underlying heart disease. If the left bundle branch is blocked, the heart will have a different activation pattern compared to when the right bundle branch is blocked.

In contrast, premature ventricular contractions (PVCs) involve early contractions of the ventricles that can happen for various reasons, such as stress or caffeine intake, but are not directly linked to a pathway block. A second-degree heart block, type I, is characterized by a progressive lengthening of the PR interval and is generally a different conduction issue not related to bundle branch pathways. An idioventricular rhythm occurs when the ventricles themselves take over pacing at a slow rate, typically due to