What Are the Causes of an Enlarged Heart?

By China Zmuida

Cardiomegaly, or enlarged heart, is a symptom of another condition. According to the Mayo Clinic, the term cardiomegaly refers to what your physician may see on an x-ray before a complete diagnosis is made on the exact cause of your enlarged heart. There are various causes that can be attributed to the development of an enlarged heart.

Blood Pressure/Disease

Your heart can become enlarged due to high blood pressure. When you have high blood pressure, your heart has to work overtime to get blood circulating to your organs. If you develop diseases of your heart valves, your heart can enlarge. Diseases caused by congenital heart defects, infections, treatments for cancer and connective tissue disorders can also lead to an enlarged heart.


When you have anemia, your red blood cells are unable to carry oxygen to your tissues. If you don't treat anemia, you can develop an irregular heartbeat. As a result, your heart has to overcompensate for the lack of oxygen. According to the Mayo Clinic, in rare cases, your heart may become enlarged due to lack of treatment over a prolonged time.

Cardiomyopathy and Arrhythmia

Cardiomyopathy occurs when your heart becomes thickened and hard. As the disease progresses, your heart works harder to move blood, which will cause it to enlarge. Arrhythmia occurs when your heart isn't able to pump blood effectively. As a result, the heart can become enlarged.

Other Causes

Pulmonary hypertension is a condition where your heart has to work overtime to pump blood between your heart and lungs. The condition can cause the right side of your heart to become larger. Thyroid conditions, such as hypothyroidism and hyperthyroidism, can make the heart bigger. Hemochromatosis causes excessive iron to build up in your heart muscle, which causes your left ventricle to become large. Amyloidosis causes abnormal proteins to flow in your blood. As a result, the proteins can become lodged in your heart, which causes the heart to function abnormally and become large.


According to the Mayo Clinic, one of the most serious complications resulting from an enlarged heart is when your left ventricle becomes enlarged. An enlarged left ventricle can lead to heart failure, whereby your heart loses its ability to pump blood efficiently. Other complications can lead to blood clots, heart murmurs and cardiac arrest or sudden death.

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