pulmonary stenosis

Pulmonary stenosis results from abnormal development of the pulmonary valve leaflets, leading to fusion or thickening that obstructs blood flow from the right ventricle (RV) to the pulmonary artery. This increases RV pressure, causing RV hypertrophy over time, and if severe, can lead to right-sided heart failure and cyanosis (via right-to-left shunting if a PFO/ASD is present). Etiologies include congenital causes (isolated valvular stenosis, Noonan syndrome, congenital rubella syndrome, Tetralogy of Fallot) and rarer acquired causes (carcinoid syndrome, rheumatic disease - though rare for pulmonic valve). Clinically presents with a systolic ejection murmur heard best at the left upper sternal border, radiating to the back, that increases with inspiration; there may be a widely split S2 due to delayed pulmonic valve closure. Severe cases can present with exertional dyspnea, fatigue, syncope, or signs of right heart failure (jugular venous distension, hepatomegaly, peripheral edema). Diagnosis is confirmed via echocardiography, showing valve morphology, gradient across the valve, and RV hypertrophy. Cardiac catheterization can also measure pressure gradients. Management depends on severity: mild cases are monitored, while moderate-to-severe cases may require balloon valvuloplasty or surgical valve repair/replacement. Associated conditions to remember for boards: Noonan syndrome (pulmonic stenosis + short stature + webbed neck), congenital rubella syndrome (PS + PDA + cataracts), Tetralogy of Fallot (PS + VSD + overriding aorta + RVH), and carcinoid syndrome (right-sided valve lesions including pulmonic stenosis and tricuspid regurgitation due to serotonin exposure)