Your body craves oxygen. In fact, each organ in your body, from your toe muscles to your brain, needs oxygen to ensure you’re able to eat, move, and perform everything else you do throughout the day. While your body contains an impressive set of veins and arteries carrying blood and oxygen to where they’re needed, sometimes this system breaks down and leads to pulmonary hypertension.

Here are five things to know about pulmonary artery function and how it relates to pulmonary hypertension (PH) and pulmonary arterial hypertension (PAH).

1. Pulmonary Arteries Are the Only Arteries in the Body That Carry Oxygen-Poor Blood

To ensure each tissue in your body receives enough oxygen, long tubes called arteries carry blood — containing oxygen and other nutrients — to different parts of your body. Your tissues can then take what they need from the blood to function properly.

Most arteries are responsible for delivering oxygen-rich blood to different parts of your body. The pulmonary arteries are unique because they’re the only arteries to carry deoxygenated (oxygen-poor) blood — rather than oxygenated (oxygen-rich) blood — throughout your body. In fact, these arteries are responsible for ensuring your blood is full of oxygen to deliver to organs throughout the body.

These arteries make up a part of the pulmonary circuit, a system in your body responsible for moving blood back and forth between your heart and your lungs to refill blood with oxygen. Your pulmonary circuit consists of a pulmonary trunk — or one main artery — that departs directly from the heart. This trunk then splits into two arteries, a left pulmonary artery that goes to your left lung, and a right pulmonary artery that goes to your right lung. These arteries then branch into smaller and smaller arteries in each lung.

Deoxygenated blood travels from the heart through your pulmonary arteries to each of your lungs, where they are refilled with more oxygen. Afterward, pulmonary veins carry the oxygenated blood back to your heart to be pumped back out to different parts of your body.

2. Healthy Pulmonary Arteries Don’t Require a Lot of Pressure To Circulate Blood

When the pulmonary circuit is healthy, the average blood pressure within the pulmonary arteries should be fairly low — about 11 to 19 millimeters of mercury (often abbreviated as mm Hg). This pressure is much lower than systemic blood pressure, or the pressure in your other arteries. The blood pressure in the pulmonary circuit is lower because there are so many thin pulmonary arteries for the blood to flow through. As a result, not much pressure is needed to direct your blood toward the lungs, where your deoxygenated blood is refilled with more oxygen.

If blood pressure in your pulmonary arteries increases, your heart must work much harder to keep pumping blood, which can damage or injure your heart muscle over time. This course of events is known as pulmonary hypertension. If severe or untreated PH progresses, it can lead to heart failure.

3. Increased Pressure in the Pulmonary Arteries Has Several Potential Causes

Why would the blood pressure in your pulmonary arteries increase? Some common causes of pulmonary hypertension include medical conditions such as:

• Blockage or narrowing of your pulmonary arteries
• Chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) or emphysema
• Congenital heart disease
• Connective tissue disease, such as scleroderma
• Coronary artery disease
• Liver disease

The exact cause determines which one of the five types of pulmonary hypertension you or your loved one may have. For example, if your high blood pressure is the result of a narrowing or blockage in your arteries, then you’re likely to have pulmonary arterial hypertension.

Several myPHteam members have shared what they believe caused their pulmonary hypertension. One member wrote, “I’ve had clots in my lungs twice.”

Specifically, this member was referring to a condition known as a pulmonary embolism. In a pulmonary embolism, a blood clot from another part of the body breaks off and travels through the body’s network of veins up to the heart and then to the lungs.

Blood clots can get stuck in a vein and cause a blockage in blood flow. This process can be compared to how a clogged pipe causes water to back up into a sink. Left untreated, the blockage raises pulmonary artery blood pressure and can lead to pulmonary hypertension.

Additionally, several genetic mutations are linked to PH. Having a family history of pulmonary hypertension is a sign that you have heritable pulmonary arterial hypertension. When the exact cause of PH is not known, it’s called idiopathic pulmonary arterial hypertension.

4. Many Tests Can Help Diagnose Pulmonary Hypertension

Regardless of the exact cause, all types of pulmonary hypertension are linked to increased pressure in your pulmonary arteries. Signs and symptoms of pulmonary hypertension include shortness of breath and chest pain. Health care providers typically use a few different tests to determine if pulmonary artery pressure is high and confirm a diagnosis of PH.

The most definitive test to diagnose pulmonary hypertension is called right heart catheterization. During this procedure, a doctor inserts a catheter (long tube) into the right side of the heart through a blood vessel. Besides measuring pressure, doctors can also use the catheter to look for any blood clots or see if blood vessels have been narrowing.

Several imaging tests, such as chest X-rays and CT scans, can help diagnose pulmonary hypertension. An echocardiogram offers a less invasive method for measuring pulmonary artery pressure. In an echocardiogram, ultrasound is used to create moving pictures of your heart and help doctors determine the structure of your heart and surrounding vessels. The echocardiogram can also be used to determine how well blood is moving through your heart and arteries.

Doctors can use other exams to determine whether a person may have high pressure in their pulmonary arteries. For example, blood tests and imaging can be used to look for clots. Since high pressure in the pulmonary arteries often leads to your heart being overworked, an electrocardiogram (ECG) — which checks the heart’s electrical activity — can also identify any heart damage.

5. PH Treatments Can Help Improve Blood Flow Through the Pulmonary Arteries

Although there’s no known cure for pulmonary hypertension, different treatment options can help increase the flow of blood through the pulmonary arteries and improve quality of life.

A range of medications can help to relieve or remove the cause of the pressure within the pulmonary arteries. Blood thinners or anticoagulants can help to prevent blood clots. Vasodilator therapies, including calcium channel blockers like nifedipine, can help relax and open the pulmonary arteries or other blood vessels to relieve pressure. Diuretics help eliminate excess fluid that can put pressure on the heart and lungs.

Other classes of medications have emerged to help improve pulmonary artery pressure, including:

• Endothelin receptor antagonists, such as ambrisentan (Letairis) and bosentan (Tracleer)
• Phosphodiesterase inhibitors (PDE 5 inhibitors), such as sildenafil (Revatio) and tadalafil (Adcirca)
• The prostacyclin analog drug treprostinil (Orenitram)
• The selective IP receptor drug selexipag (Uptravi)

Read more about specific medications in this list of treatments for pulmonary hypertension.

For more serious cases of pulmonary hypertension, your doctor may recommend surgery to achieve pressure relief. For example, a balloon pulmonary angioplasty can be used to reduce pressure within the pulmonary artery. A lung transplant may be recommended in severe cases.

It’s also important to support your overall well-being by getting as much physical activity as is appropriate for your health and eating a healthy diet. Some recommended foods include:

• Fruits like apples or oranges
• Leafy, green vegetables like spinach or kale
• Legumes like beans and lentils
• Nuts and seeds
• Whole grains like brown rice or whole-grain bread

Talk with your doctor about what kind of activity and food will be best for you, in combination with your pulmonary hypertension treatment.

Talk With Others Who Understand

On myPHteam, the social network for people with heart disease and their loved ones, more than 54,000 members come together to ask questions, give advice, and share their stories with others who understand life with pulmonary hypertension.

Do you have more questions about how pulmonary arteries function? How was your diagnostic journey with pulmonary hypertension? Share your knowledge and questions in the comments below, or start a conversation by posting on your Activities page.