Pulmonary hypertension
- Lesion
Pulmonary hypertension is high pressure in the lung arteries. It thickens their walls and strains the right ventricle until it fails.
What it is
Pulmonary hypertension is a mean pulmonary artery pressure above the normal range at rest, measured by right heart catheterisation; guideline cut-offs have been lowered in recent years. It is grouped by mechanism into five WHO groups. Most cases are secondary to left heart disease or lung disease and hypoxia. Whatever the cause, pulmonary arteries remodel and the right ventricle hypertrophies (cor pulmonale).
Structure
- All forms: medial hypertrophy of muscular and elastic pulmonary arteries; right ventricular hypertrophy.
- Large arteries: atheroma-like intimal plaques in severe cases.
- Small arteries and arterioles: intimal fibrosis, muscularisation of arterioles that normally lack muscle.
- Plexiform lesions in idiopathic and congenital-shunt cases; organised, recanalised thrombi in thromboembolic disease.
Step by step
- A trigger raises flow, resistance or downstream pressure: shunts, lost capillary bed, hypoxic vasoconstriction, emboli or high left atrial pressure.
- Endothelium is injured: less nitric oxide and prostacyclin, more endothelin and thromboxane.
- In BMPR2 haploinsufficiency, endothelial and smooth muscle cells proliferate instead of restraining growth.
- Smooth muscle hypertrophies and intima fibroses; small arteries narrow and some are obliterated.
- Resistance and pressure rise further, a self-reinforcing loop.
- The right ventricle thickens, dilates and finally fails.
WHO groups of pulmonary hypertension
| Group | Mechanism | Examples |
|---|---|---|
| 1 | Disease of small pulmonary muscular arteries | Idiopathic, BMPR2, systemic sclerosis, HIV, drugs, shunts |
| 2 | Left heart disease | Mitral stenosis, left ventricular failure |
| 3 | Lung disease or hypoxia | COPD, interstitial lung disease, sleep apnoea, altitude |
| 4 | Chronic thromboembolic and other obstructions | Recurrent pulmonary emboli |
| 5 | Unclear or multifactorial | Sarcoidosis, haematologic and metabolic disorders |
Clinical notes
- Exertional dyspnoea, fatigue, syncope and chest pain; then signs of right heart failure (edema, raised jugular pressure).
- Group 1 disease is classically a young woman with idiopathic or heritable disease, or a patient with systemic sclerosis.
- Treatment follows the cause: oxygen and treatment of lung disease, anticoagulation and surgery for chronic emboli, vasodilators for group 1.
Test yourself
Think of the answer, then tap the question to see it.
What gene is most often mutated in heritable pulmonary arterial hypertension?
BMPR2, a bone morphogenetic protein receptor of the TGF-β receptor family; most carriers never develop disease.
What is a plexiform lesion?
A tuft of capillary-like channels within a dilated small pulmonary artery, characteristic of advanced pulmonary arterial hypertension.
Which WHO group contains COPD and sleep apnoea?
Group 3, pulmonary hypertension due to lung disease and/or hypoxia.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Pulmonary Hypertension (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.