An enlarged heart (cardiomegaly) may have various causes. But it's usually the result of high blood pressure (hypertension) or coronary artery disease.
An enlarged heart may not pump blood effectively, resulting in congestive heart failure. Cardiomegaly may improve over time. But most people with an enlarged heart need lifelong treatment with medications.
The heart enlarges in response to damage to the heart muscle. Up to a point, enlargement permits the heart to continue to pump blood normally. As enlargement progresses, though, the heart's pumping ability declines.
Dilated cardiomyopathy is the main type of cardiomegaly. In dilated cardiomyopathy, the walls of both the left and right side of the heart (ventricles) become thin and stretched. The result is an enlarged heart.
In the other types of enlarged heart, the heart's muscular left ventricle becomes abnormally thick. High blood pressure usually causes left ventricular enlargement (hypertrophy), while hypertrophic cardiomyopathy is an inherited condition.
Generally speaking, the heart's pumping ability is better preserved when the enlarged heart is "thick" rather than "thin."
Causes of an Enlarged Heart
The most common causes of an enlarged heart are blockages in the heart's blood supply (coronary artery disease) and high blood pressure. An enlarged heart can have many other causes, including:
Frequently, no cause for an enlarged heart is identified. This is known as idiopathic dilated cardiomyopathy.
Symptoms of an Enlarged Heart
Most often, an enlarged heart causes no symptoms. If an enlarged heart becomes unable to pump blood effectively, symptoms of congestive heart failure can develop:
Shortness of breath (especially with exertion or when lying flat)
Increased abdominal girth
Palpitations or skipped heartbeats
Symptoms vary widely in people with an enlarged heart. Some may never have symptoms. Others may have mild symptoms that remain unchanged for years. And some may experience steadily worsening shortness of breath.