CausesBy Mayo Clinic staff
An enlarged heart can be caused by conditions that cause your heart to pump harder than usual or that damage your heart muscle. Sometimes the heart enlarges and becomes weak for unknown reasons (idiopathic).
Conditions associated with an enlarged heart include:
- High blood pressure. Having high blood pressure can make it so that your heart has to pump harder to deliver blood to the rest of your body, enlarging and thickening the muscle.
- Heart valve disease. Four valves within your heart keep blood flowing in the right direction. If the valves are damaged by such conditions as rheumatic fever, a heart defect, infections (infectious endocarditis), connective tissue disorders, certain medications or radiation treatments for cancer, your heart may enlarge.
- Disease of the heart muscle (cardiomyopathy). Cardiomyopathy is the thickening and stiffening of heart muscle. In early stages of cardiomyopathy, you may have no symptoms. As the condition worsens, your heart may enlarge to try to pump more blood to your body.
- Heart attack. Damage done during a heart attack may cause an enlarged heart.
- A heart condition you're born with (congenital heart defect). Many types of congenital heart defects may lead to an enlarged heart, as defects can affect blood flow through the heart, forcing it to pump harder.
- Abnormal heartbeat (arrhythmia). If you have an arrhythmia, your heart may not pump blood as effectively as it would if your heart rhythm were normal. The extra work your heart has to do to pump blood to your body may cause it to enlarge.
- High blood pressure in the artery connecting your heart and lungs (pulmonary hypertension). If you have pulmonary hypertension, your heart may need to pump harder to move blood between your lungs and your heart. As a result, the right side of your heart may enlarge.
- Low red blood cell count (anemia). Anemia is a condition in which there aren't enough healthy red blood cells to carry adequate oxygen to your tissues. Left untreated, chronic anemia can lead to a rapid or irregular heartbeat. Your heart must pump more blood to make up for the lack of oxygen in the blood when you're anemic. Rarely, your heart can enlarge if you have anemia for a long time and you don't seek treatment.
- Thyroid disorders. Both an underactive thyroid gland (hypothyroidism) and an overactive thyroid gland (hyperthyroidism) can lead to heart problems, including an enlarged heart.
- Excessive iron in the body (hemochromatosis). Hemochromatosis is a disorder in which your body doesn't properly metabolize iron, causing it to build up in various organs, including your heart muscle. This can cause an enlarged left ventricle due to weakening of the heart muscle.
- Rare diseases that can affect your heart, such as amyloidosis. Amyloidosis is a condition in which abnormal proteins circulate in the blood and may be deposited in the heart, interfering with your heart's function. If amyloid builds up in your heart, it can cause it to enlarge.
- Enlarged heart. American Heart Association. http://www.americanheart.org/presenter.jhtml?identifier=4517. Accessed Dec. 9, 2010.
- Cardiomyopathies. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merckmanuals.com/professional/sec07/ch084666/ch084666a.html. Accessed Dec. 9, 2010.
- What is cardiomyopathy? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/dci/Diseases/cm/cm_all.html. Accessed Dec. 9, 2010.
- Cardiomegaly on chest X-ray. In: Ferri FF. Ferri's Clinical Advisor 2011: Instant Diagnosis and Treatment. Philadelphia, Pa.: Mosby Elsevier; 2011. http://www.mdconsult.com/books/page.do?eid=4-u1.0-B978-0-323-05610-6..00065-2--s0020&isbn=978-0-323-05610-6&sid=1093880434&type=bookPage§ionEid=4-u1.0-B978-0-323-05610-6..00065-2--s0020&uniqId=229713866-3#4-u1.0-B978-0-323-05610-6..00065-2--s0020. Accessed Dec. 9, 2010.
- Grogan M (expert opinion). Mayo Clinic, Rochester, Minn. Jan. 3, 2011.