What is a key feature of a Bundle Branch Block (BBB)?

A key feature of a Bundle Branch Block (BBB) is the presence of a wide QRS duration. This occurs because the electrical impulses that typically travel down both the right and left bundle branches of the conduction system are delayed or blocked in one of the branches. As a result, the depolarization of the ventricles is asynchronous, which lengthens the duration of the QRS complex on an electrocardiogram (ECG).

A wide QRS complex typically measures greater than 0.12 seconds. This characteristic helps differentiate Bundle Branch Blocks from other types of conduction abnormalities, as a normal conduction will show a narrow QRS duration due to the efficient transmission of the electrical impulses through both branches simultaneously.

The nature of a BBB directly impacts ventricular conduction, leading to the wider QRS, which is essential for clinicians to recognize when interpreting ECGs. Understanding this feature is crucial for diagnosing potential underlying conditions and assessing the significance of the block in the context of patient symptoms and history.