Pathophysiology
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.