A bifascicular block refers to a medical condition where there is a blockage in two of the three major branches of the heart's electrical system. It is also referred to as a bundle branch block because the pathways that conduct electrical impulses in the heart's ventricles are blocked. Some synonyms for bifascicular block include right bundle branch block, left bundle branch block, and bundle branch hemiblock. Another synonym for this condition is fascicular block, which occurs when there is a blockage in one of the two pathways that branch off from the main bundle of His. Regardless of its name, a bifascicular block can cause symptoms such as fatigue, dizziness, and chest pain and require medical attention.