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Enlarged Heart?

Published: May 14, 2012
Dear TeenHealthFX,
Hello. Just wondering, I've heard alot lately of athletes dying from enlarged hearts. What causes an enlarged heart? What are the symptoms of an enlarged heart? Is it genetic?
Signed: Enlarged Heart?

Dear Enlarged Heart?,


Very good question.  This is a long answer but bear with us because to understand it, FX needs to give you some background.


An enlarged heart isn't a condition in itself, but a symptom of an underlying problem that is causing the heart to work harder than normal. The range of underlying problems falls generally into two main categories - pathological (linked to actual disease of the heart muscle disease) and physiological (linked to other causes which are overworking the heart muscle, such as high blood pressure or thyroid diseases). In some cases, an enlarged heart is asymptomatic (has no symptoms). When symptoms do occur, it may be because the heart fails to pump blood effectively and this leads to a syndrome known as congestive heart failure. Symptoms may include:

  •        Breathing problems
  •       Shortness of breath, cough
  •       Dizziness
  •       Irregular heartbeat (arrhythmia)
  •      Heart palpitations
  •      Fluid retention.

Some of the many causes of enlarged heart include:

    • Coronary artery disease - fatty deposits or plaques build up inside one or more of the coronary arteries (arteriosclerosis). This constant silting narrows the artery. This reduces the oxygen supply, which is the fuel for the pump.
    • High blood pressure (hypertension) - blood pumps with more force than usual through the arteries, which puts strain on the heart. Causes of high blood pressure include obesity and a sedentary lifestyle.
    • Idiopathic dilated cardiomyopathy - disease of the heart muscle, the cause of which is unknown. Enlarged or 'dilated' heart is one of the most common types of cardiomyopathy. Some of the symptoms include chest pain and fainting spells.
    • Myocarditis - an infection of the heart that is generally caused by a virus. A person may have a viral illness first and later have symptoms of congestive heart failure.
    • Heart valve disease - for example, a faulty mitral valve allows blood to flow backwards, which means the affected heart chamber has to contract with more force than usual.
    • Cardiac ischaemia - reduced blood flow to the heart. This condition can cause heart pain (angina) and often results from coronary artery disease.
    • Previous heart attack - a weakened heart muscle may enlarge in order to keep up with the demands of pumping blood around the body.
    • Thyroid disease - the thyroid gland regulates many metabolic functions. Untreated, a thyroid condition can lead to high blood pressure, high blood cholesterol levels, irregular heartbeat and enlargement of the heart.
    • Obesity - carrying too much body fat is a risk factor for high blood pressure, which in turn can cause the heart to enlarge.
    • Lack of exercise - leading a sedentary lifestyle is a known risk factor for a range of conditions, including coronary heart disease and high blood pressure.
    • Old age - as we get older, our arteries lose some of their elasticity. This 'stiffening' of the blood vessels causes high blood pressure, which is a risk factor for enlarged heart.

An enlarged heart is diagnosed using a number of tests including:

  • Medical history - including a physical examination.
  • Chest x-ray - this allows the doctor to see the overall shape and size of the heart and lungs.
  • Echocardiogram - sound waves sent to a special machine present a picture of the beating heart, so the doctor can see the heart as its chambers contract and relax.
  • Doppler ultrasound - shows blood flow through the heart valves. This test is often performed in conjunction with the echocardiogram.
  • Electrocardiogram - measures electrical activity in the heart and can help diagnose an enlarged heart.

Treatment depends on the underlying cause but can include:

  • Medications to stop the heart from enlarging any further.
  • Treatment to address the underlying problem, such as diet, exercise and medication to help control high blood pressure, or surgery to replace a faulty heart valve.
  • Regular cardiovascular exercise.
  • Low fat diet.
  • Dietary adjustments to reduce blood cholesterol levels.
  • Frequent medical check-ups to make sure the treatments are working.

So to answer your question about athletes and enlarged hearts, here is some more specific information.
"Athletes heart" is a common term for an enlarged heart that is usually associated with repeated strenuous exercise.  This is normal and there is usually no danger of heart problems. "Athlete's heart" becomes dangerous when the muscle wall of the lower chamber of the heart (Cardiomyopathy) or the walls of the heart's chambers thicken abnormally (Hypertrophic cardiomyopathy). 

Hypertrophic cardiomyopathy (called athletic heart muscle disease) usually appears in young people, often in athletes.  Due to the increased workload required of it, the heart will increase physiologically by enlarging its chambers and muscle mass, thus increasing the volume of blood pumped per stroke. As a result, the heart has to contract less frequently and at rest will beat as few as 40 times per minute. The average number of beats per minute in a non "athlete's heart" is 70 beats.


The heart of a person with cardiomyopathy is enlarged in a bad way, and there's virtually no place for the blood to go.   At a certain point, the heart's chambers (the septum) may become so thickened that it blocks the flow of blood through the lower left chamber (left ventricle). The thickened wall may push on the heart valve between the two left heart chambers (mitral valve), making it leaky. The thickened muscle walls also prevent the heart from stretching as much as it should to fill with blood.  This leads to heart failure

The cause of hypertrophic cardiomyopathy is not known. In about one-half of cases, the disease is inherited. An abnormal gene has been identified in these patients. In cases that are not hereditary, a gene that was normal at birth may later become abnormal.

People of any age can develop hypertrophic cardiomyopathy. Often people with hypertrophic cardiomyopathy have no symptoms. Unfortunately, the first sign of the condition may be sudden death caused by an abnormal heart rhythm. When symptoms do appear, they include shortness of breath on exertion, dizziness, fainting, fatigue, and chest pain. The American Heart Association reports that 36% of young athletes who die suddenly have probable or definite hypertrophic cardiomyopathy.


If you are concerned about this or any heart condition, please discuss it with your family doctor.

Signed: TeenHealthFX