Myxoma of the heart: clinical and experimental observations.

During the past 12 years, 13 patients with atrial (10 left and 3 right) myxoma have been treated. The tumors of the left atrium produced signs and symptoms of mitral valve obstruction and/or subacute bacterial endocarditis and those of the right atrium manifestations of tricuspid valve disease or of pulmonary embolus or hypertension. The diagnosis was established by angiocardiography in 8 patients, at surgery performed for suspected mitral stenosis in 3 patients, and at autopsy in 2 patients. Resection of the atrial myxoma alone in 5 patients or with atrial septum where the atrial myxoma was attached in 4 or with the whole right atrial wall where the atrial myxoma was attached in one patient was performed and all are doing well without evidence of recurrence. Studies of experimentally produced 1.5-3 cm in diameter left atrial thrombus in 30 dogs divided into 5 groups and followed cineangiocardiographically and sacrificed from 14 days to 6 months indicated that the implanted thrombus is absorbed over a 3 to 6 month period. These experimental and human left atrial thrombi were found to be histologically and histochemically different from human atrial myxomas. The electron microscopic studies performed on some of the resected atrial myxomas suggested that the atrial myxoma cells are active cells of endotheilial origin. These observations suggest that atrial myxoma is a primary tumor of the heart which can mimic other clinical entities, and the results of its surgical treatment are gratifying and long lasting.