CARDIAC TUMORS



Tumors involving the heart may be primary or metastatic; both are rare. Although a variety of me­tastatic tumors has been described in the heart, the most common are malignant melanomas, leu­kemia, and lymphomas. The treatment of metas­tatic tumors is treatment of the primary malig­nancy.
Primary cardiac tumors may be benign or ma­lignant. Myxoma is the most common primary tumor of the heart and is usually benign. Almost all malignant cardiac tumors are sarcomas, an­giosarcoma and rhabdomyosarcoma being the most frequent. It is impossible prior to histologic examination to distinguish benign from malig­nant tumors, but malignant tumors are more likely to present with evidence of metastases, invasion, or rapid growth. Tumor type may be identified occasionally from tissue at the time of peripheral embolectomy. Malignant primary tumors of the heart have a very poor prognosis.

Myxomas may arise from the endocardial sur­face of any cardiac chamber, but the majority arise from the left atrium, most commonly in the region of the fossa ovalis. They are usually peduncu­lated. As a general rule, 10 per cent of cardiac myxomas manifest malignant characteristics and 10 per cent arise in locations other than the left atrium. Occasionally they can be bilateral and usually present in one of three general ways: [1] progressive interference with mitral valve func­tion that causes decreased exercise tolerance, dyspnea on exertion, and pulmonary edema; syncope or presyncope may occur; (2) stroke or occlusion of a major systemic artery due to an em­bolus; (3) systemic manifestations that include fever, wasting, arthralgias, malaise, anemia, or Raynaud’s phenomenon.

If the left atrial myxoma interferes with mitral valve function, a regurgitant valvular murmur may occur. A murmur resembling mitral stenosis may be present owing to obstruction of the valve orifice during diastole. The intensity of the mur­mur may change with changes in body position. An early diastolic sound termed a “tumor plop” may occur secondary to movement of the tumor toward the left ventricle in early diastole. The erythrocyte sedimentation rate, gamma globulins, and white blood cell count may be elevated. The cause of the systemic manifestations is not clear but may result from products secreted by the tumor, necrotic tumor debris, or an immunologic reaction.

Cardiac myxoma is usually diagnosed by ech­ocardiography. Two-dimensional echocardiogra­phy shows the tumor location and movement with the cardiac cycle. Cardiac catheterization with an­giocardiography usually is not necessary when the diagnosis has been established noninvasively and is associated with risk of tumor embolus.

Cardiac myxomas should be excised surgically once identified. A recurrent or second myxoma occurs following resection in a small number of patients. Atrial myxoma occasionally may behave as a malignant tumor and demonstrate metastases.