This patient should undergo replacement of the pulmonary valve. She has Noonan syndrome, which is an autosomal dominant disorder commonly associated with congenital cardiac lesions, one of which is pulmonary valve stenosis. The pulmonary valve is usually dysplastic in patients with Noonan syndrome and thus is not amenable to balloon intervention. This patient has severe pulmonary valve stenosis demonstrated by physical examination; features include a late-peaking palpable systolic ejection murmur located at the second left intercostal space, absence of an ejection click, and features of right ventricular pressure overload. An ejection click may be audible in patients with pulmonary valve stenosis, but as the severity progresses, the click disappears owing to loss of valve pliability. This patient's echocardiogram confirms severe pulmonary valve stenosis with a peak systolic gradient of 62 mm Hg and mean systolic gradient of 45 mm Hg. Intervention is recommended owing to the severity of obstruction despite the absence of symptoms. Surgical valve replacement is recommended given the dysplastic valve features and presence of coexisting moderate pulmonary valve regurgitation. Most patients with severe pulmonary valve stenosis are treated with balloon valvuloplasty, but this patient has a dysplastic valve related to Noonan syndrome and moderate pulmonary valve regurgitation; thus, pulmonary valve replacement is recommended.

Patients with pulmonary valve stenosis without a history of endocarditis or pulmonary valve replacement do not require endocarditis prophylaxis.

Exercise testing could help determine whether the patient has exercise limitation related to her pulmonary valve stenosis but would not change the recommendation for intervention; thus, it is not required.

Clinical observation, with continued participation in competitive sports, is not advised in patients with severe pulmonary valve stenosis regardless of symptom status because of the risk of progressive right heart failure.