Myxomas in the left atrium often grow from a stalk and can swing freely with the flow of blood like a tetherball. This swinging may plug and unplug the valve over and over again, so that the blood flow stops and starts intermittently. The tumor may damage the mitral valve, so that blood leaks through it, creating a heart murmur that a doctor may hear with a stethoscope. Based on the way a murmur sounds, a doctor must consider whether it results from a leak caused by damage from a tumor, a very rare cause, or from a more common cause, such as rheumatic heart disease. Pieces of a myxoma or blood clots that form on the surface of the myxoma may break off, circulate to other organs, and block blood vessels there.
Symptoms depend on which vessel is blocked.
Less common noncancerous heart tumors, fibromas and rhabdomyomas, may grow directly from the heart's fibrous tissue cells and muscle cells. Rhabdomyomas, the second most common type of primary tumors, develop in infancy or childhood, usually in a rare childhood disease called tuberous sclerosis. Other primary heart tumors, including primary cancerous tumors, are extremely rare, and no good treatment exists. The children who get them usually live less than 1 year. Several tests are used to diagnose heart tumors.