What Is Pulmonary Arterial Hypertension? Causes, Symptoms, and Treatments to Know

Pulmonary arterial hypertension (PAH) is a rare type of pulmonary hypertension, which is high blood pressure in the lungs. PAH happens when the small blood vessels in your lungs become stiff and narrow, making it difficult for blood to pass through.

As a result, your heart must work harder to push blood into your lungs. This increases the blood pressure in your pulmonary arteries. Over time, PAH worsens and can eventually lead to heart failure. But there are treatments that can slow these effects and improve symptoms. 

What are the symptoms of pulmonary arterial hypertension?

People with PAH often have no symptoms at first. Early symptoms include shortness of breath or lightheadedness during exercise. As PAH advances, you may notice symptoms like:

• Shortness of breath

• Feeling tired

• Dizziness or fainting

• Chest pain

• Swelling in your legs

It’s important to note that PAH is very rare. And there are other, more common, medical conditions that can also cause these symptoms.

What causes pulmonary arterial hypertension?

There are many reasons why people develop PAH:

• Genetics: PAH can be caused by gene mutations that lead to stiffening of the pulmonary arteries. People can inherit these genetic mutations from their parents. This type of PAH runs in families.

• Medications and substances: Some medications used to treat cancer, like dasatinib and mitomycin-C, can lead to PAH. Methamphetamine use can also cause PAH. 

• Medical conditions: Some medical conditions increase your risk of developing PAH. These include connective tissue disorders, human immunodeficiency virus (HIV), portal hypertension from cirrhosis, and some types of congenital heart disease.

• Pulmonary veno-occlusive disease (PVOD) or pulmonary capillary hemangiomatosis (PCH): These are two rare causes of PAH. PVOD is when blood clots and scar tissue form in the veins of your lungs. PCH occurs when too many small blood vessels grow in your lungs.

Sometimes it’s not clear why someone develops a medical condition. These cases are called “idiopathic.” Almost half of people with PAH have idiopathic PAH. This means many people with PAH never find how or why they developed the condition.

How is pulmonary arterial hypertension diagnosed?

Pulmonary arterial hypertension can take time to diagnose. If you have symptoms of PAH, your healthcare team may ask you to start with lung function tests, blood tests, or a CT scan of the lungs to help rule out other common causes of shortness of breath, like asthma, COPD, or anemia. 

More specialized testing for PAH includes:

• Electrocardiogram (ECG), which is a test that can be performed in your doctor’s office. An ECG shows the electrical conduction in your heart. It can also show evidence of structural changes in your heart that could be caused by higher than normal blood pressures in your lungs.

• Echocardiogram (TTE), which is an ultrasound of your heart that looks at the size of your heart chambers and your heart’s pumping power. During this test the pressure inside different parts of your heart can be estimated. 

• Cardiac catheterization, which is where a catheter is inserted into a blood vessel in your arm or leg and moved into your heart. This allows for direct measurement of the pressure inside the heart chambers.

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PAH is diagnosed when both of the following are true:

• The pressure inside your pulmonary arteries is high

• The increased pressure isn’t caused by problems in the left side of your heart, chronic lung disease, or blood clots in your lungs

How is pulmonary arterial hypertension treated?

PAH is treated with medication to lower blood pressure in your lungs. Treatment for PAH may include:

• Calcium channel blockers: Medications like amlodipine and diltiazem are commonly used for hypertension (high blood pressure). They can also lower blood pressure in the arteries inside your lungs. 

• Endothelin antagonists: Endothelin antagonists block the activity of endothelin, a substance that causes your blood vessels to narrow. Endothelin antagonists like ambrisentan and bosentan, have the opposite effect. They keep your blood vessels dilated (open) and lower blood pressure in your lungs. 

• Phosphodiesterase 5 (PDE5) inhibitors: PDE5 inhibitors are a group of medications that help relax blood vessels. PDE5 inhibitors, like sildenafil and tadalafil, help treat PAH. 

• Guanylate cyclase stimulators: Riociguat is a medication that helps dilate blood vessels in your lungs. Studies show that riociguat can help lower pulmonary artery pressure and reduce shortness of breath in people with PAH. 

• Prostacyclin analogues and prostacyclin receptor agonists: Prostacyclins cause blood vessels to dilate and prevent formation of small blood clots. Medications like treprostinil and selexipag act like prostacyclin in your body and help treat PAH. 

• Diuretics: Diuretics (water pills) help remove extra fluid from your body. Diuretics like furosemide and bumetanide can help people with PAH and heart failure. 

• Lung transplant: In severe cases, people with PAH may need a lung transplant. 

New medications for pulmonary arterial hypertension

More medications are being developed to help treat PAH. In 2024, the FDA approved sotatercept for the treatment of PAH. A clinical trial found that people taking sotatercept could walk farther and had less shortness of breath with exercise. 

Sotatercept works differently from other medications to treat PAH. It’s a fusion protein that binds to and traps some of the molecules that signal growth in the pulmonary arteries. Sotatercept helps prevent the walls of blood vessels from becoming thicker, which means there’s more room for blood flow. 

What’s the prognosis like for someone with pulmonary arterial hypertension?

PAH is a serious, life-threatening condition. Symptoms typically get worse as the condition progresses. Prognosis refers to how healthcare professionals expect a condition to affect a person’s health over time. The prognosis for someone with PAH depends on several factors, including how severe symptoms are, the underlying cause of PAH, and their overall health. 

Treatment can relieve symptoms and increase overall survival. Combination therapy (using more than one type of treatment) and new medications are improving prognosis for people with PAH.

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Written by:

Christine Giordano, MD

Christine Giordano, MD, is board-certified in general internal medicine. She received her medical degree from Rutgers New Jersey Medical School and completed residency at Thomas Jefferson University.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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