What is a common feature of patients with LBBB (Left Bundle Branch Block) regarding the QRS complex?

Patients with Left Bundle Branch Block (LBBB) characteristically exhibit a QRS duration that is typically greater than 0.12 seconds. This elongation occurs because the conduction of electrical impulses through the left bundle branch is interrupted. As a result, there is a delay in depolarization of the left ventricle compared to the right ventricle, leading to a wider QRS complex.

The key understanding here is that a prolonged QRS duration is intrinsic to the pathophysiology of LBBB. This change in duration is important for diagnosing and differentiating LBBB from other cardiac conduction issues. In contrast, a narrow QRS duration would indicate normal conduction within the ventricles, which is not consistent with LBBB. Similarly, the presence of delta waves pertains to conditions such as Wolff-Parkinson-White syndrome, and normal QRS morphology does not apply in the context of LBBB, where the morphology is typically altered due to the block.