Atrial myxomas are benign tumors of the heart which occur in the atria of the heart. The tumors can occur on either side, but over 80% are found on the left side. These tumors tend to occur most often in people with a family history of cardiac tumors, but also seem to have in increased incidence in those with histories of embolic disorders. They also occur with more frequency in those with mitral stenosis or atrial fibrillation.

The tumor itself is a pedunculated mass of varying size. It is often asymptomatic when small, but symptoms occcur more often as the size increases, or in situations with increase in cardiac output or changes in position. Position is a significant factor, as the tumor is essentially a ball of tissue on a stalk. With a change in body position, gravity can pull the tumor to a position where it blocks the outflow through the atrial valve on the left, or pulmonary valve on the right. A cardinal sign of an atrial myxoma is the so-called "tumor plop", a distinctive sound heard during auscultation of the heart when a tumor of sufficient size is present in the atrium.

Symptoms of atrial myxoma:

Other symptoms can occur including cough, fever, weight loss, cyanosis, clubbing of the digits, edema, neurological changes, or malaise among others.

The tumors mainly cause problems due to restriction of the outflow of blood from the heart, and the backpressure they cause. They can also result in the formation of emboli, metastasis of the tumor, the development of cardiac arrythmias, and in sudden death in 15% of sufferers. Symptoms often mimic those of either right or left congestive heart failure depending on the location of the tumor. The only cure is surgical removal.