What is the pathogenesis of pulmonary hypertension?
Pathogenesis of Pulmonary Hypertension Pulmonary hypertension (PH) is a condition marked by increased pulmonary artery pressure due to narrowing, obstruction, or remodeling of the pulmonary vasculature. The pathogenesis is multifactorial, involving endothelial dysfunction, vasoconstriction, vascular remodeling, inflammation, and sometimes genetic mutations. Step-by-Step Pathogenesis 1. Endothelial Cell Dysfunction The initial trigger may be hypoxia, inflammation, mechanical stress, or toxins. Leads to: ↓ Vasodilators : nitric oxide (NO), prostacyclin (PGI₂) ↑ Vasoconstrictors : endothelin-1, thromboxane A₂ Result: Persistent pulmonary vasoconstriction 2. Vascular Remodeling Structural changes in pulmonary arteries: Intimal fibrosis (scarring of the inner vessel layer) Smooth muscle hypertrophy and hyperplasia (in the media) Adventitial thickening These changes cause narrowing and stiffening of pulmonary arteries → ↑ resistance. 3. I...