Asymmetric septal hypertrophy in a 41-year-old woman with Noonan's syndrome.

A 41-year-old woman had Noonan's syndrome. Her heart was complicated by asymmetric septal hypertrophy, hypertrophy of the left ventricular free wall, severe pulmonary stenosis, and right ventricular hypertension. On autopsy, a quantitative histologic analysis of the heart revealed that the area of disarray was limited both to the ventricular septum and the left ventricular free wall as in a normal heart. This is not typical of hypertrophic cardiomyopathy because the extent of disarray is high in most cases of hypertrophic cardiomyopathy. Some form of hypertrophic cardiomyopathy, however, seemed to be present in this patient because right ventricular pressure overload did not affect the left ventricular free wall. To clarify the relation between hypertrophic cardiomyopathy and Noonan's syndrome, quantitative histologic analysis is necessary.