There is a natural pacemaker in the heart, known as the sinoatrial (SA) node. Made up of a group of cells in the atria, or right upper chambers of the heart, the SA node is responsible for sending electrical impulses which cause the heart to beat. After traveling through the upper chambers, these impulses pass through a small group of cells known as the atrioventricular (AV) node. Before going into the ventricles, or lower chambers of the heart, the impulses travel down a track of fibers known as the bundle of His, which consist of a left and right bundle branch. If there is a blockage preventing the electrical impulses from traveling through these branches, the condition is known as a bundle branch block.
A person with no previous history of a heart problem can have a bundle branch block. However, it is commonly seen in individuals with an existing type of heart disease. There are a variety of cardiovascular disorders that fall under this broad category. Although the names may vary, a heart disease is an illness that affects the heart and its surrounding structures. Any type of heart dysfunction can lead to the onset of a blockage of one or both bundle branches.
Heart attacks, also known as a myocardial infarction, can cause a bundle branch block. A heart attack occurs when deposits of cholesterol, known as plaque, build up in the walls of the heart's arteries. This may cause the arteries to rupture and blood clots to form. Arteries can become completely blocked with clots and induce a heart attack. A myocardial infarction can prevent electrical impulses from adequately entering the bundle branches and can cause a blockage in the left, right or both branches.
Another common heart defect that may lead to a bundle branch block is heart failure. When the heart is no longer strong enough to adequately pump enough blood to meet the body's need, this condition can occur. If the heart is unable to pump blood as it should, there is an opening for all sorts of cardiovascular problems. Blood clots can result from blood that may become backed up, as the heart is not able to efficiently distribute it. A blood clot can travel down into one of the bundle branches leading to a blockage.
Symptoms of a bundle branch block will vary. Common symptoms include heart rate changes, in particular a slower heart rate, dizziness and fainting. Some people do not experience any symptoms. In these situations, an individual may only become aware of the condition while undergoing a medical test on the heart, such as a electrocardiogram (EKG), for other reasons.
Everyone with a bundle branch block will not need treatment. However, treatment options are available for individuals who need it. Most commonly, medication will be given to treat any underlying causes of the blockage. Individuals experiencing troublesome symptoms such as fainting may need more advanced treatment, such as a pacemaker, to regulate heartbeats and overall functionality. Any abnormal sensations in the heart should be further investigated by a health care professional, so a proper diagnosis can be made and treatment can be advised.