In such cases, the mass of tumor is often relatively small. Extensive solid tumor in and around the heart is less common but may resemble constrictive pericarditis or effusive-constrictive pericarditis. Usually, the only effective treatment in metastatic involvement of the heart is relief of cardiac tamponade. Otherwise, treatment depends on the nature of the primary tumor. Hamartomas, rhabdomyomas, and fibromas are the most common benign cardiac tumors in children.
Cardiac hamartomas occur in tuberous sclerosis, a syndrome that produces multisystem hamartomas.
Myxomas consist of scattered stellate cells embedded in a mucinous matrix. About 70 percent of myxomas are in the left atrium, and most of the remaining 30 percent are in the right atrium. Myxomas are most often manifested clinically by mechanical hemodynamic effects, which often simulate mitral or tricuspid stenosis when they obstruct the valve orifice. They may stimulate mitral or tricuspid regurgitation when they interfere with valve closure or cause a so-called wrecking ball trauma to the mitral or tricuspid valve. Intermittent obstruction of the valve orifice can lead to dramatic symptoms, such as syncope, or to remarkable changes in the physical signs, which are sometimes related to changes in body position.