A QRS complex wider than 0.12 seconds most likely indicates which of the following?

A QRS complex that measures wider than 0.12 seconds is indicative of a disruption in the normal conduction pathways within the ventricles. The most common reason for a widened QRS complex is the presence of a bundle branch block, which occurs when there's a delay in the electrical conduction traveling through one of the bundle branches that deliver impulses to the ventricles.

This condition results in the ventricles not contracting in a coordinated manner, leading to a longer duration of the QRS wave on an electrocardiogram (ECG). Typically, in bundle branch blocks, one ventricle is activated earlier than the other, causing a widening of the QRS complex due to asynchronous ventricular depolarization.

Observing a wider QRS complex does not align with normal conduction, atrial enlargement, or ventricular tachycardia in the context described. Normal conduction would present a QRS duration of less than 0.12 seconds. Atrial enlargement impacts the P wave morphology rather than the width of the QRS complex, and while ventricular tachycardia can produce a wide QRS complex, it typically corresponds with additional clinical features and a more complex assessment than simply measuring the width alone. Therefore, the presence of a QRS complex wider than