If the QRS complex is widened and downwardly deflected in lead V1, a left bundle branch block is present. If the QRS complex is widened and upwardly deflected in lead V1, a right bundle branch ...

What varies with the presence of bundle branch block is (1) anterograde conduction (timing of local V, onset and ending/morphology of the QRS) and (2) retrograde conduction (timing of conduction ...

A 76-year-old woman presents with a persistently rapid heart rate that she attributes to her pacemaker. What does the ECG ...

This results in widening of the QRS complex as described below. Approximately 50% of left bundle branch blocks are associated with structural heart disease, while the other half are idiopathic or ...