Block of conduction of electrical impulses along the Bundle of His or along one of its bundle branches.
Comment:
The Bundle of His conducts the electrical impulse from the atrioventricular node into the ventricles. THe Bundle of His divides into right and left bundle branches. A universal feature of a bundle branch block is a prolongation of the time required for depolarization of a portion of the ventricles, reflected in an abnormality of the QRS complex.