What Causes an Enlarged Heart?

An enlarged heart isn’t a condition in itself — it’s a symptom caused by different cardiovascular issues.

Having a big heart can be a good thing, when you’re talking about emotions, but when doctors talk about an enlarged heart, or cardiomegaly, it’s usually a sign that something else is going on with your ticker.

Hearts are often described as the size of a human fist, but research suggests that sex, height, body weight and age play a part in determining what a “normal” heart size is. If yours is bigger than it should be, your doctor might tell you that you have an enlarged heart. And unless you’re an athlete whose heart has gotten bigger from strenuous exercise, an enlarged heart can indicate a problem.

“The heart is a sac,” explains Fernando Fleischman, MD, a cardiothoracic surgeon at Keck Medicine of USC and associate professor of clinical surgery at the Keck School of Medicine of USC. “When the heart begins to fail, it isn’t able to push blood out. As a result, blood stagnates, and the heart gets bigger — similar to a balloon with too much fluid in it.”

One symptom you might experience, if you have an enlarged heart, is trouble breathing when you exert yourself.

“If you decide to exercise, for example, you might find that you are short of breath,” Dr. Fleischman says. “Or, you might not be able to get up and get to the bathroom without huffing and puffing.”

You may also feel fatigued, dizzy or light-headed. You can have swelling in your legs, ankles, feet or abdomen, as well.

There are a number of health conditions that can cause an enlarged heart — these four are among the most common.

1. High blood pressure

If you have high blood pressure, or hypertension, your heart has to work harder. This extra work your heart is doing can cause the heart to enlarge. High blood pressure can lead to left ventricular hypertrophy, where the heart’s left pumping chamber becomes thickened, weak and stiff, interfering with normal blood flow.

2. Heart valve problems

If the flaps that open and close the chambers of the heart aren’t functioning correctly, it can lead to an enlargement of the heart, according to Dr. Fleischman.

“Every beat of the heart is supposed to eject a quantity of blood, but when the valve isn’t working properly, that doesn’t happen, and the blood that isn’t pumped out makes the heart get bigger,” he says.

3. Heart disease

“Heart disease can cause failure of the heart muscle by taking away its oxygen supply,” Dr. Fleischman notes. “This decreased oxygen supply means that the heart can’t beat, so it can’t push out blood, and the heart enlarges.”

4. Cardiomyopathy

Cardiomyopathy is a broad term used to describe diseases that can lead to a rigid, thick or enlarged heart muscle. There are different types of cardiomyopathies, but one in particular, known as ischemic cardiomyopathy, is caused by coronary artery disease.

Reducing your risk for coronary artery disease, high blood pressure and heart disease can help prevent your heart from becoming enlarged in the first place. Dr. Fleischman recommends eating a well-balanced diet, maintaining a healthy weight and not smoking to reduce your risk.

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