Echocardiography in combined discrete and hypertrophic subaortic stenosis.

A 10-year-old boy with discrete subaortic stenosis had coexisting abnormal systolic anterior motion of the mitral valve, demonstrated by echocardiography, a sign normally taken as indicating the presence of idiopathic hypertrophic subaortic stenosis. Surgical removal of a fibromuscular diaphragm abolished the echocardiographic signs of discrete subaortic stenosis but abnormal systolic anterior motion of the mitral valve persisted. A severe low cardiac output state complicated immediate recovery after removal of the left ventricle outflow obstruction, and was overcome only with considerable difficulty. The presence of hypertrophied septal muscle, and the associated small left ventricular cavity size, was thought to be the immediate cause of these problems, so that recognition of marked septal hypertrophy, together with abnormal anterior systolic movement of the mitral valve, should serve as a warning that similar difficulties are likely to bae encountered by other patients, after removal of the obstruction in subaortic stenosis. In our experience other forms of left ventricle outflow tract obstruction have not been found to show such a marked degree of asymmetric septal hypertrophy, but this does not mean it may not occur.