PAH treatment terms glossary

When you have pulmonary arterial hypertension (PAH), there are certain terms you may hear throughout your treatment. Understanding these terms may help you have more productive talks with your healthcare provider.

General PAH Terms

This is a list of general terms related to PAH.

Agonist (AG-uh-nist)
A substance that starts a response when it hits a receptor.1
Anemia (uh-NEEM-ee-uh)
A drop in the number of red blood cells in the body.1 Red blood cells carry oxygen throughout the body. Some symptoms of anemia include dizziness, fatigue, and shortness of breath.2
Antagonist (an-TAG-uh-nist)
A substance that binds to a receptor to block a response in the body.1
Artery (AHR-tuh-ree)
A vessel that carries blood from the heart to other parts of the body.1
Combination Therapy
A way of treating PAH with more than one medication at a time. This may help target different pathways of PAH.3
Dyspnea (disp-NEE-uh)
Difficulty breathing.1
Edema (uh-DEEM-uh)
Swelling caused by a buildup of fluids in the body.1
Endothelin (en-doe-THEE-lin)
A natural substance produced by the body that is found in blood.1 In PAH, an excess of endothelin may cause arteries to tighten.3
This is a drug that blocks the endothelin receptors and is used for the treatment of PAH.3
Functional class (FC)
Functional class is a common way to measure the severity of each patient’s PAH. The World Health Organization (WHO) has defined 4 functional classes. The higher the class, the more serious the condition.4
Functional Class I for PAH Patients

Physical activity is not limited.

Can do regular activity without feeling dizzy or faint, being short of breath, feeling tired, or having chest pain.

Functional Class II for PAH Patients

Physical activity is slightly limited.

Comfortable at rest, but regular activity causes patients to feel dizzy or faint, be short of breath, feel tired, or have chest pain.

Functional Class III for PAH Patients

Greater limitation of physical activity.

Comfortable at rest, but activity is very limited. Less than regular activity causes patients to feel dizzy or faint, be short of breath, feel tired, or have chest pain.

Functional Class IV for PAH Patients

Unable to do any physical activity without discomfort.

May be short of breath, feel tired even at rest. Any physical activity increases discomfort.

Heritable (HARE-it-uh-bul)
Heritable traits are those that can be passed down to following generations through a family’s genes.1 People with heritable PAH come from families with a higher risk of the disease.
Hypoxia (hy-POX-ee-uh)
A lower than normal amount of oxygen in the body.1
Idiopathic (id-ee-o-PATH-ik)
Describes a disease or condition in which the cause is not known.1 About one-third of PAH cases are idiopathic.3
Maintenance dose
Your highest tolerated dose. This is the dose you will continue to take on a regular basis once the titration phase is over, unless your healthcare provider tells you otherwise.5
Microgram (my-kro-gram)
A unit of measure equal to one millionth of a gram. Not to be confused with milligrams.1
Nitric oxide
A natural substance produced by the body that causes blood vessels to expand, increasing blood flow in PAH.1
A chemical found in the air that has no color, taste, or smell. Your body needs oxygen to use the energy in food.1 PAH makes it difficult to get oxygen from the air into the bloodstream. This may contribute to the symptoms of PAH.
PAH Progression
The worsening of PAH. In a clinical trial of UPTRAVI, PAH disease progression was defined as a serious event, such as hospitalization for PAH; the need to start injectable PAH medications or chronic oxygen therapy; lung transplantation; or a decline in 6-minute walk distance combined with worsening of functional class or need for additional PAH therapy; or death.5
A series of reactions that happen in a particular order. The body has many pathways.6 The 3 pathways that PAH treatments target are endothelin, nitric oxide, and prostacyclin.7
Also called phosphodiesterase type-5 inhibitor, this is a therapy for PAH.3
Pharyngitis (fair-in-JI-tis)
Inflammation of the throat with dryness and pain. Also called a sore throat.1
Prostacyclin (pros-tuh-SY-clin)
A natural chemical that is produced inside the body that helps open your arteries.1 In PAH, the body may not make enough prostacyclin.3
Pulmonary arterial hypertension (PAH)
PAH is high blood pressure in the arteries that carry blood from the heart to the lungs. It’s a serious condition that can make it difficult for blood to flow through your lungs.3
Pulmonary artery
The artery that carries blood from the heart to the lungs.1
Pulmonary hypertension (PH)
PH is high blood pressure in the blood vessels of the lungs. PAH is one of several types of PH.3
Receptor (re-SEP-tur)
A part of a cell that binds with specific substances found in the body in order to do a task.1
Right ventricle (VEN-truh-kuhl)
The heart has 4 chambers. This ventricle is on the right side of the heart and pumps blood to the lungs.1
Scleroderma (sclair-o-DERM-uh)
A progressive disorder in which the body’s tissues harden. In some cases, this disorder can also affect the blood vessels.1 It’s estimated that between 7% and 12% of patients with scleroderma also suffer from PAH.8
Specialty pharmacy
A pharmacy that delivers medicines that are not available through a local pharmacy. It often provides services including:
  • Shipping medicine directly to a patient’s home
  • Monthly check-ins with patients to make sure they’ve completed required testing
  • Being available to answer questions a patient or caregiver may have about receiving medicine
Titration (tahy-TREY-shun)
The process of finding the right dose for you. This process will involve your healthcare provider starting you on the lowest dose and stepping you up to higher doses over the first several weeks of treatment. You will continue until you reach your maintenance dose.5
Vasoconstriction (vay-zo-con-STRIC-shun)
The narrowing of blood vessels.1
Vasodilation (vay-zo-di-LAY-shun)
The widening of blood vessels.1
World Health Organization (WHO)
The public health arm of the United Nations.9 This organization defined the 4 functional classes described above. It has also outlined different types of pulmonary hypertension called WHO Groups.8
WHO Groups
World Health Organization (WHO) divides pulmonary hypertension into 5 groups (labeled 1-5). PAH is WHO Group 1.8

PAH Test Terms

There are many tests your healthcare provider may order during diagnosis of and treatment for PAH. This section defines some of the most common tests.

This procedure uses echoes of ultrasonic waves to take a picture of the walls and internal structures of the heart.1
Electrocardiogram (ECG/EKG)
A test that records the heart's electrical activity. This test also shows whether your heart's rhythm is steady or irregular, and may show whether your right ventricle is enlarged or strained.10
Liver function test (LFT)
LFT is a blood test that tracks liver function.1 Certain PAH medicines come with a risk of liver problems. For this reason, your doctor may request an LFT from time to time.
Pulmonary function test (PFT)
PFTs are breathing tests that measure how much air the lungs can hold, how well they move air, and how well they supply the body with oxygen.11
Right-heart catheterization (RHC) (cath-uh-tur-i-ZAY-shun)
This test involves passing a thin tube (catheter) into the right side of the heart in order to test heart function and measure blood pressure in the arteries of the lung. Right-heart catheterization is required for a definitive diagnosis of PAH.11
6-minute walk distance (6MWD) or 6-minute walk test (6MWT)
This measures the distance a patient can walk in 6 minutes. It is one test that a doctor may perform to assess a patient’s condition throughout treatment.3