Which clinical scenario may indicate the presence of a bundle branch block?

The presence of a bundle branch block is indicated by a prolonged QRS complex that also exhibits a specific morphology on an electrocardiogram (ECG). When a bundle branch block occurs, electrical conduction is delayed through one of the bundle branches (either the right or left), leading to altered depolarization of the ventricles. This delay causes the QRS complex to be wider than the normal duration, typically exceeding 0.12 seconds.

Additionally, the morphology refers to the distinctive patterns seen in the QRS complex depending on which branch is blocked. For example, a right bundle branch block often presents with a characteristic "M"-shaped pattern in leads V1 and V2, while a left bundle branch block may show a "W"-shaped pattern in those same leads. These changes in morphology, along with the prolonged duration, are key indicators of bundle branch block.

Understanding these details about the QRS complex is essential for identifying bundle branch blocks and for interpreting the significance of this arrhythmia in a clinical context. This knowledge aids in proper diagnosis and management of patients with potential conduction system abnormalities.