Abnormal diastolic movement of the interventricular septum caused by a prolapsing right atrial myxoma.

A 40 year old woman with cough and exertional dyspnoea was found to have a large right atrial myxoma by M mode and cross sectional echocardiography. Prolapse of the tumour into the right ventricle occurred during diastole with sufficient force to cause mechanical distortion of the interventricular septum. Septal motion became normal after surgical resection of the myxoma.