An enlarged heart, also known as cardiomegaly, generally occurs as a symptom of another health condition. Many people go unaware that they have this problem until it is diagnosed, commonly by an x-ray. Undergoing a chest x-ray for any number of reasons could potentially diagnose an enlargement of the heart. Once the problem is noticed, doctors typically send patients for more advanced cardiovascular diagnostic tests. There can be many different causes of an enlarged heart and some people may have a combination of causes.

Cardiomyopathy is a heart disease which causes the heart muscle to become weak. The disease may cause the muscle to become stiff and thick, which can affect the heart's functionality. As the disease progresses, the heart will have to work harder to pump blood throughout the body. An enlarged heart may be the result of the heart working overtime to compensate for the weakened muscle. In addition to the heart muscle, diseases which affect the heart valves can cause the heart to become enlarged.

An arrhythmia is a condition in which the heart beats in an irregular rhythm. Having an irregular heart rhythm usually means that the heart beats too fast or too slow. The abnormal pace of beating can hinder the heart from performing normally. This is generally because the blood is unable to circulate in the manner it should. For this reason, an enlarged heart may occur due to the added stress placed on the organ by an arrhythmia.

Hypertension, also referred to as high blood pressure, is one of the most common causes of an enlarged heart. High blood pressure can be dangerous for a number of reasons. It can lead to heart attacks and strokes and it cause cause the heart to become enlarged. This is generally due to the extra work the condition places on the heart. There can also be high blood pressure in the arteries stemming from the heart into the lungs, and this condition, known as pulmonary hypertension, can also cause the heart to enlarge.

There may be non-heart-related causes of an enlarged heart. An underactive or overactive thyroid can cause this problem. Pregnancy can be another cause not related to the heart. The heart will have to pump out much more blood than normal while a woman is pregnant, and this can create a stressful environment for the heart. Additionally, anemia, which occurs when a person is not producing an adequate amount of red blood cells, is another condition that may cause a heart enlargement.

Enlarged heart symptoms may include shortness of breath, breathing problems, swelling, fatigue, dizziness and tiring easily. Some people with this condition may not have any symptoms though. If a chest x-ray shows a larger than normal heart, the patient may be sent for diagnostic tests that may include a cardiac computerized tomography (CT) scan, an electrocardiogram, magnetic resonance imaging (MRI) or echocardiogram. Many individuals may have a combination of these tests. For a person with a heart enlargement, there are numerous medications available to eliminate symptoms and help the person live a normal and productive life.