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.

This article will discuss five things to know about pulmonary artery function and how it relates to pulmonary hypertension (PH) and pulmonary arterial hypertension.

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

To ensure that 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 it needs from the blood in order to properly function.

Whereas most arteries are responsible for delivering oxygen-rich blood to different parts of your body, you also have some very special arteries — pulmonary arteries. 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 that 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 it 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 High Pressure To Circulate Blood

When the pulmonary circuit is healthy, the blood pressure within the pulmonary arteries should be fairly low — about 11 to 20 millimeters of iron (mm Hg). This pressure is much lower than systemic blood pressure, or the pressure in your other arteries. The blood pressure there is lower because the distance between your heart and lungs is very short. As a result, not much additional pressure is needed to direct your blood toward the lungs, where your deoxygenated blood is refilled with more oxygen.

However, sometimes the blood pressure within your pulmonary arteries begins to increase. Suddenly, your heart must work much harder to keep pumping blood, which can begin to damage or hurt your heart muscle over time. This course of events is also called pulmonary hypertension. Severe or untreated PH can lead to heart failure.

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

Why would the blood pressure within your pulmonary arteries increase? Some common causes include:

• Blockage or narrowing of your pulmonary arteries
• Chronic lung diseases, such as emphysema
• Congenital heart disease
• Connective tissue disease
• Coronary artery disease
• Genetics
• Liver disease

The exact cause also determines which one of the five types of pulmonary hypertension you or your loved one may be living with. 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 venous system (network of veins) up to the heart and then to the lungs.

Because the blood clot is too large to travel unimpeded through the blood vessels of the lungs, it gets stuck and thus causes a blockage in blood flow. This process can be compared to how a clogged pipe causes water to back up into a sink. If 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.

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. As a result, health care providers typically use multiple tests that directly measure or help infer high pulmonary artery pressure to confirm a diagnosis of PH.

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

An echocardiogram offers a less invasive method for measuring pulmonary artery pressure. In an echocardiogram, an 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. Alternatively, 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. Several PH Treatments Improve Blood Flow Through the Pulmonary Arteries

Although there’s no known cure for pulmonary hypertension, several different treatments can help improve the flow of blood through the pulmonary arteries. Some of the simplest treatments are lifestyle changes like increasing your amount of physical activity and eating a healthy diet to improve your heart’s ability to pump blood. 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

In addition, certain 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 such as certain calcium channel blockers — including nifedipine (Procardia) — can relax the pulmonary arteries or other blood vessels to relieve pressure.

However, in more serious cases of pulmonary hypertension, a health care professional may recommend surgery to achieve the same pressure relief. For example, a balloon pulmonary angioplasty can be used to reduce pressure within the pulmonary artery.

Talk With Others Who Understand

On myPHteam, the social network for people with heart disease and their loved ones, more than 51,000 members come together to ask questions, give advice, and share their stories with others who understand life with pulmonary hypertension.

Are you curious about how pulmonary arteries function? Share your knowledge and questions in the comments below, or start a conversation by posting on your Activities page.