Clinical meaning
Pulmonary valve stenosis involves narrowing of the pulmonary valve orifice, obstructing blood flow from the right ventricle to the pulmonary artery. The increased resistance to ejection causes right ventricular pressure overload and compensatory hypertrophy. Over time, sustained pressure overload leads to myocardial fibrosis, reduced compliance, and eventual right heart failure. Severe stenosis reduces pulmonary blood flow, impairing gas exchange and causing systemic hypoxemia through right-to-left shunting via a patent foramen ovale if present.
Exam relevance
Risk factors: - Congenital heart defect (most common cause) - Noonan syndrome - Carcinoid syndrome (acquired valvular disease) - Rheumatic heart disease - History of rubella exposure in utero - Family history of congenital heart disease
Diagnostics: - Echocardiography with Doppler to measure transvalvular gradient - Right heart catheterization for definitive gradient measurement - ECG showing right axis deviation and RV hypertrophy - Chest X-ray showing post-stenotic dilation of pulmonary artery - Continuous pulse oximetry monitoring - BNP level to assess right ventricular strain