Right ventricular biopsy findings of hypertrophic cardiomyopathy in a patient with Noonan syndrome

We report right ventricular ultrastructure in a 20-year-old patient with Noonan's Syndrome. Initial left ventricular and septal myocardial hypertrophy, observed at 2 months without obstruction, progressed to biventricular involvement over 18 years. Histopathologic evidence of cardiomyocytic disarray, with ultrastructural evidence of myofibrillar disarray, confirmed typical biopsy findings of hypertrophic cardiomyopathy on the right ventricular side of the septum.