Pulmonary arterial hypertension (PAH) is one form of a broader condition known as pulmonary hypertension, which is high blood pressure in the lungs. In this rare, progressive, life-threatening condition, the small arteries in the lung become narrowed, thickened or blocked or destroyed, followed by increased blood pressure.

The exact cause of PAH remains unknown. Approximately 15-20% of patients with PAH have heritable forms of PAH. People with heritable PAH have either:

(1) an autosomal dominant genetic condition associated with mutations in the BMPR2 gene or other recently identified genes now associated with HPAH or other forms of PAH or associated conditions such as pulmonary capillary hemangiomatosis or pulmonary veno-occlusive disease, or;

(2) are members of a family in which PAH is known to occur as primary disease.

Right heart catheterization.

• Echocardiography
• Blood tests
• Cardiac computerized tomography
• Pulmonary function tests
• Electrocardiography（ECG or EKG）
• X-ray

Although there is no cure for PAH, there are medications and procedures that can slow the progression of the disease and improve patients' quality of life.

Specific therapeutic drugs:
There are four categories of specific therapeutic drugs, each targeting different pathways to treat PAH, mainly either by relaxing and opening up blood vessels (i.e. vasodilation), or reverse the vessel from overgrowing and getting thicker in the first place (i.e. anti-proliferation). Depending on the patient's condition, doctors may use these drugs individually or in combination.

Phosphodiesterase-5 inhibitors: inhibit the enzyme phosphodiesterase-5, which breaks down cyclic guanosine monophosphate (cGMP), a molecule involved in relaxing smooth muscle and dilating blood vessels. By increasing levels of cGMP, these medications help to reduce pulmonary artery constriction.

Endothelin receptor antagonists: target the endothelin pathway to block the effects of endothelin, a substance that constricts blood vessels. By inhibiting endothelin receptors, these drugs promote vasodilation and improve blood flow in the pulmonary arteries.

Prostacyclin analogs: Prostacyclin analogs, are potent vasodilators that help to relax and widen the blood vessels in the lungs, reducing pulmonary arterial pressure.

Activin signaling inhibitors (ASI): Reduce inflammation of the blood vessels and inhibit the proliferation of smooth muscle cells and endothelial cells that line the inner wall. This prevents the thickening and narrowing of pulmonary arteries and reduces pulmonary hypertension.

• High dose calcium channel blockers: Drugs such as diltiazem and nifedipine are vasodilators which open up blood vessels. But they only benefit certain patients.
  
  
• Anticoagulation: help prevent blood clots from forming in blood vessels, but may increase the risk of bleeding and complications.

Patients with PAH should adopt lifestyle changes to maintain their health, including:

• Quitting smoking
• Maintaining a healthy weight
• Avoiding rigorous activities, such as weightlifting, that can put excessive strain on your lungs and heart
• Refraining from traveling to high altitudes
• Avoiding activities that may lead to exhaustion
  
  

National Organization for Rare Disorders (NORD): https://rarediseases.org/rare-diseases/pulmonary-arterial-hypertension/

American Lung Association: https://www.lung.org/lung-health-diseases/lung-disease-lookup/pulmonary-arterial-hypertension

7th World Symposium on Pulmonary Hypertension, Treatment algorithm for pulmonary arterial hypertension: https://publications.ersnet.org/content/erj%3A%3A%3Aearly%3A%3A%3A2024%3A%3A%3A08%3A%3A%3A01%3A%3A%3A13993003.01325-2024.full.pdf

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