Pulmonary arterial hypertension (PAH) is a rare but serious type of high blood pressure. It mimics several other heart and lung conditions. PAH causes many of the same symptoms as heart disease and asthma. Distinguishing between those conditions and PAH can be difficult, but several tests and tools can help your doctor make a diagnosis.

PAH is high blood pressure that affects the arteries of your lungs and the right side of your heart. Your pulmonary arteries and capillaries carry blood from your heart to your lungs, where your blood drops off oxygen-depleted cells and picks up oxygen-rich cells. If your pulmonary arteries are narrowed or blocked, it can cause the blood pressure inside of them to rise. Over time, the increased pressure weakens the right side of your heart and your pulmonary arteries. This can ultimately lead to heart failure and even death.

PAH is difficult to spot and diagnose, even when your doctor is looking for it during a physical exam. The symptoms of PAH mimic those of other similar conditions. Even as PAH progresses, your doctor may have trouble distinguishing it from other heart and lung conditions.

Your doctor will assess your medical history and use one or more tests to determine what’s causing your symptoms.

To help diagnose PAH, your doctor should assess your personal risk factors for the condition. For example, they should look for any conditions that might contribute to PAH or make the disease worse. You have an increased risk of PAH if you have:

  • heart disease
  • congenital heart defects
  • scleroderma
  • HIV
  • a family history of PAH

Your doctor may perform genetic screening to see if you have genes linked to PAH.

Your doctor may use the following methods to diagnose PAH:

Blood test

A blood test can help your doctor learn what’s in your blood. They may be able to identify substances related to PAH. It can also help them rule out other conditions.

Chest X-ray

If you have advanced PAH, a chest X-ray may show the enlarged part of your heart. However, this imaging test doesn’t always provide enough information to diagnose PAH.

CT scan

A CT scan creates layer-by-layer pictures of your organs. This allows your doctor to check for artery narrowing, blockages, or damage.

MRI scan

An MRI scan allows your doctor to create a picture of your body’s blood vessels. Like a CT scan, an MRI allows them to take a layer-by-layer look at all of the organs involved.


This test measures the electrical functions of your heart, which are responsible for making it beat regularly, in rhythm, and without error. A slight change in those electrical impulses can have serious consequences for your heart and body.


An echocardiogram uses sound waves to create a picture of your heart. With this test, your doctor can see if any part of your heart has grown enlarged or isn’t beating properly.

Your doctor can use two types of echocardiograms. In a Doppler echocardiogram, your doctor places a receiving device on your chest. In a transesophageal echocardiogram, your doctor places an imaging device into your esophagus.

Your doctor can use an echocardiogram to diagnose several cardiac conditions, including PAH. In most cases, they can identify PAH with an echocardiogram. Even if they can’t confirm a PAH diagnosis, they can use this test to help rule out other conditions.

Heart catheterization

If you have an echocardiogram that’s inconclusive, your doctor may ask you to undergo heart catheterization. This test allows them to measure the pressure in your arteries and heart with using small, flexible tube. They insert this tube through a blood vessel in your neck or groin and thread it to your heart.

Pulmonary function test

This test allows your doctor to see how much air your lungs can hold. During this procedure, they’ll also assess how the air flows into and out of your lungs. They may need to do this test several times to check for changes in how your lungs function.

After conducting these tests, your doctor may diagnose you with PAH or another heart or lung condition. Your specific treatment plan and outlook will vary, depending on your diagnosis. Ask your doctor for more information about your specific condition, treatment plan, and long-term outlook.