Pulmonary Arterial Hypertension (PAH) develops due to high blood pressure in the arteries that go from the heart to the lungs. This disorder may be life-threatening, but it can be managed with effective and timely treatment. The treatment depends on the causes of the disease, so it’s important to understand the common causes. This article attempts to answer the question of “what are the causes of PAH?”.

1. Family history
People with a family history of PAH are at a higher risk of developing it. The BMPR2 gene has been linked to familial pulmonary hypertension. The disease is inherited in an autosomal dominant pattern (one defective gene copy is enough to cause the condition), but only about 20% of people with a defective gene copy develop it. It’s advisable to consult a doctor for guidance if one has a family history of the condition.

2. Heart-related diseases or disorders
People born with heart diseases or disorders are more likely to develop PAH. Congenital heart disease, wherein a child is born with a defect in the heart structure that interferes with blood circulation, is a common illness that can lead to PAH.

3. Blood clots
Blood clots in certain areas of the lungs can also result in PAH. In some cases, the clots do not dissolve with time and may cause blockages in the blood vessels, leading to PAH. Sometimes, these clots can travel through the blood vessels and reach the arteries, where they cause scar-like tissue that narrows the arteries and hinders blood flow. This form of PAH, known as Chronic Thromboembolic Pulmonary Hypertension (CTEPH), can also be life-threatening, but it is a treatable condition. The clots can exist for years before symptoms start showing. It’s recommended to get a thorough checkup if one has a personal or family history of CTEPH.

4. Lung diseases
Diseases of the lungs, like cirrhosis or portal hypertension, can also cause PAH. Chronic Obstructive Pulmonary Disease (COPD), obstructive sleep apnea, and pulmonary fibrosis are some other causes of PAH. These diseases reduce the amount of oxygen that reaches the lungs, causing the arteries to narrow and increasing blood pressure in the lungs. This, in turn, can lead to PAH.

5. HIV
Although rare, PAH is a complication of HIV infections. HIV-induced PAH reduces an individual’s chances of survival by nearly 50 percent, and HIV-infected persons are at a higher risk of developing PAH than others.

6. Medications
People using methamphetamine are at a higher risk for developing PAH. Additionally, these patients have poorer long-term prognoses despite therapy as compared to other PAH patients. Research has associated methamphetamine use with Idiopathic PAH (IPAH), and a study has suggested that IPAH patients are much more likely to have used stimulants than PAH patients with other known risk factors.