A bundle branch blockage affects the heart's electrical system by blocking electric impulses to the ventricle on that side of the heart, as the American Heart Association explains. The impulse must detour around the blockage, which causes the affected ventricle to beat a fraction of a second slower than the other ventricle. Bundle branch blockages may occur on the left, right or both sides of the heart.
The causes of a bundle branch blockage in the left side of the heart include heart disease and cardiomyopathy, according to Mayo Clinic. The causes of a right-side blockage include heart attacks, congenital heart abnormalities and pulmonary embolisms. Infections and high blood pressure can cause a blockage in either side of the heart. The symptoms of blockage include fainting, or a dizzy feeling that resembles fainting may also occur. Most people with bundle branch blockages have no symptoms and only discover they have a blockage when they undergo an electrocardiogram.
The risk for bundle branch blockages increases with age and for those with prior heart conditions, as Mayo Clinic reports. No treatment exists for this condition, but patients should get medical care if there is an underlying cause. Bundle branch blockages in otherwise healthy people only require regular check-ups to ensure that the condition doesn't worsen.