Half of all primary (arising in the heart) 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 a transient drop in blood pressure because less blood is able to be pumped from the heart. Lying down typically causes the myxoma to move away from the valve and relieves the symptoms.
Other symptoms of myxomas include
Raynaud syndrome (the fingers and toes become cold and painful when exposed to cold)
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, an artery in the brain blocked by tumor emboli from a left atrial myxoma may cause a stroke, and an artery in the lung blocked by emboli from a right atrial myxoma may cause pain and coughing up of blood. Emboli are the most common complication of myxomas.
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 a high number of white blood cells (indicating inflammation), anemia, and a low number of platelets in the blood. But none of these tests is conclusive.