Understanding PAH Pathways

There are 3 known substances found in your body that help blood flow freely through your blood vessels. With PAH, too much or too little of 1 or more of these substances can result in the narrowing of the blood vessels in your lungs.

Currently, there is no diagnostic test to determine which substance has the imbalance. However, 1, 2, or all 3 of these substances could be out of balance.

PAH treatments work to correct the balance of these substances, also known as treating the pathways. There are several classes of PAH treatment, and each class works on a single pathway.

Because there is no way to tell which pathway is affected, your doctor may recommend more than 1 treatment or add a treatment to address 1 or more pathways. It’s important that you and your doctor continuously monitor your condition and set goals for your treatment. It may be necessary to adjust your treatment plan to reach your treatment goals.

Rollover the chart to learn more about each treatment class.

PDE-5 inhibitors and sGCS help to relax smooth muscle in the arteries and may increase blood flow to the lungs. These inhibitors can enhance or prolong the vasodilatory effects of cyclic guanosine monophosphate (GMP), a natural substance produced in the pulmonary vessels. These medicines are available in oral (pill) form.
Prostacyclin is a natural substance found in the body. But, if you have PAH, your body may not produce enough prostacyclin. Prostacyclin class therapies were the first type of PAH treatments discovered. They mimic the effects of natural prostacyclin by helping to keep the blood vessels open so blood can flow through the lungs and absorb oxygen. Prostacyclins can be taken orally, inhaled, or delivered through a pump.
Endothelin-1 causes blood vessels to constrict and stimulates the smooth muscle cells of the pulmonary artery to multiply abnormally. ETRAs are a type of PAH medicine that helps to open the airways and block the chemical endothelin. These medicines are available in oral (pill) form.