Pulmonary arterial hypertension (PAH) (WHO Group 1) is high blood pressure in the arteries of the lungs. The increased pressure affects the ability of the heart and lungs to work properly.
Blood vessels in the lungs are wide enough so blood can flow through them freely.
Blood vessels in the lungs narrow, making it difficult for blood to flow through them.
Nitric oxide does many different things in the body, including helping control blood pressure by opening arteries (also known as dilation) when needed.
Endothelin increases blood pressure and narrows blood vessels.
Prostacyclin works in different ways within healthy blood vessels. It helps with dilation and it helps prevent the vessels from getting blocked.
When working properly, each of these substances works in its own way to help blood flow freely through your blood vessels.
When these substances are out of balance, blood vessels in the lungs will narrow, and the heart has to work harder to pump blood to the lungs to get oxygen that is needed by the rest of the body.
This causes the symptoms of PAH.
Currently, there is no medical test to determine if 1, 2, or all 3 substances are out of balance.
Talk to your doctor about the medicines you are taking and whether you can do more to correct the imbalance.