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A myxoma is a noncancerous primary heart tumor, usually irregular in shape and jellylike in consistency.
Half of all primary heart tumors are myxomas. Three fourths of myxomas occur in the left atrium, the chamber of the heart that receives oxygen-rich blood from the lungs. Myxomas usually develop in women, typically between the ages of 40 and 60.
Some uncommon types of myxomas run in families. These hereditary myxomas (part of Carney complex, a syndrome of various noncancerous tumors) usually develop in young men in their mid-20s, and they can occur in one or more of any of the chambers of the heart.
How a Myxoma Can Block Blood Flow in the Heart
Myxomas in the left atrium often grow from a stalk and swing freely with the flow of blood, as a tetherball does. As they swing, they may move in and out of the nearby mitral valve, the valve that opens from the left atrium into the left ventricle. This swinging motion may plug and unplug the valve over and over again, so that blood flow stops and starts intermittently.
When they stand, people with a myxoma in the left atrium may feel short of breath or may faint. When a person is standing, the force of gravity pulls the myxoma into the opening of the mitral valve, blocking blood flow through the heart. This blockage causes transient heart failure. Lying down typically causes the myxoma to move away from the valve and relieves the symptoms.
Pieces of a myxoma or blood clots that form on the surface of the myxoma may break off (becoming emboli), travel through the bloodstream to other organs, and block arteries there. The resulting symptoms depend on which artery is blocked. For example, a blocked artery in the brain may cause a stroke, and a blocked artery in a lung may cause pain and coughing up of blood. Emboli are the most common complications of myxomas.
Other symptoms of myxomas include fever, weight loss, joint pain, Raynaud syndrome (the fingers and toes become cold and painful when exposed to cold), a low red blood cell count (anemia), a high white blood cell count, and a low platelet count. Anemia may cause fatigue, weakness, and paleness. A low platelet count can cause problems with blood clotting.
Myxomas are suspected based on the person's symptoms. With a stethoscope, doctors may hear a sound (heart murmur) produced by abnormal blood flow. The myxoma may block blood flow to or from the heart.
Because many symptoms of a myxoma may also be caused by many other disorders, extensive testing may be needed before a diagnosis is made.
Blood tests may show inflammation, anemia, and a low number of platelets in the blood. But none of these tests is conclusive.
The diagnosis is confirmed by echocardiography. Other procedures, including angiography, computed tomography (CT), and magnetic resonance imaging (MRI), are sometimes necessary.
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