Bundle branch block

Bundle branch blocks are conduction blocks in the left or right bundle branches. The Bundle of His divides into the left bundle branch and right bundle branch. Blocks in these conducting pathways cause the depolarisation of part of the ventricle to occur later than the rest, resulting in a wide QRS complex.

Bundle branch blocks rarely cause symptoms or need treatment in and of themselves, but they’re clinically significant in that they are often signs of heart disease. As such, patients with left bundle branch block or right bundle branch block must be evaluated for heart disease.

Etiology

• Idiopathic slowly progressive degeneration of the conduction system
• Hypertensive cardiomyopathy
• Coronary artery disease (especially acute myocardial infarction)
• Cardiomyopathy
• Myocarditis