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Medical Terms

Learn about common terms related to PAH and TYVASO.

Portrait of happy couple taking a walk outdoorsPortrait of happy couple taking a walk outdoors

6-minute walk test (6MWT)

A test that tracks how far you can walk in 6 minutes. The 6-minute walk test is done during most of your doctor visits. The distance you can walk (known as your 6-minute walk distance, or 6MWD) helps your doctor assess the impact of your treatment and determine whether your treatment plan needs to be adjusted to improve your walk distance.

Experts recommend a treatment goal* of about 1444 feet or more (440 meters) in the 6-minute walk test.

*Low-risk 6MWD threshold from the 2015 ESC/ERS Guidelines for the Diagnosis and Treatment of Pulmonary Hypertension.


Endothelin receptor antagonist (ERA)

Class of medication used in PAH. Available in oral form. Ambrisentan, bosentan, and macitentan are ERAs.


Functional class (FC)

A system of 4 classes created by the World Health Organization to assess the severity of symptoms in patients with PAH.


Phosphodiesterase type 5 (PDE-5) inhibitor

Class of medication used to treat PAH. Available in oral form. Tadalafil and sildenafil are PDE-5 inhibitors.


A natural substance in your body that helps the blood vessels in your lungs stay open so that your heart can pump blood through your lungs.

Prostacyclin Analogue

A synthetic form of prostacyclin, designed to mimic some of the effects of natural prostacyclin, that helps to keep the blood flowing through your lungs. TYVASO is an inhaled prostacyclin analogue used to treat pulmonary arterial hypertension (PAH; WHO Group 1).

Pulmonary arterial hypertension (PAH)

A condition that is characterized by high blood pressure in the arteries of the lungs. It is a chronic and progressive rare disease that affects your heart’s ability to pump blood to your lungs.


Right heart catheterization

The only test that can confirm a PAH diagnosis; measures the pressure in your heart and the arteries in your lung.


Specialty Pharmacy (SP) providers

Pharmacies that provide personalized care and are different from your local pharmacy.