What is a left bundle branch block?
A person with a left bundle branch block has an abnormality in the electrical impulse that stimulates the muscle fibers in the heart to contract. A left bundle branch block may cause the heart to beat abnormally. This abnormal impulse is discovered on an electrocardiogram, but does not usually cause symptoms. A left bundle branch block is caused by any illness that damages the heart. The most common causes of left bundle branch block include congestive heart failure or coronary artery disease.

What are the symptoms of a left bundle branch block?
Usually, a left bundle branch block does not cause symptoms. Rare symptoms of a left bundle branch block include palpitations, fatigue, faintness, fainting, and shortness of breath during activity.

How does the doctor treat a left bundle branch block?
Treatment for a left bundle branch block depends on the underlying cause. Treatment for left bundle branch block may include medications or cardiac pacemaker.