Pulmonary arterial hypertension (PAH) is high blood pressure in the pulmonary arteries. The pulmonary arteries are large blood vessels that carry blood from the right ventricle of the heart to the lungs.
PAH is different than other types of high blood pressure, such as systemic blood pressure and other forms of pulmonary hypertension, and doctors do not always know what causes it.
However, medications are available to treat PAH, and a person can also manage their symptoms through lifestyle practices, such as eating a balanced diet and getting plenty of physical activity.
In this article, we explain what PAH is and how it differs from other types of hypertension. We also look at the causes, symptoms, and treatment options.
The National Organization for Rare Disorders (NORD) describes PAH as high blood pressure in the arteries of the lungs that occurs “for no apparent reason.” In a person with PAH, the blood flows much more forcefully from the heart into the lungs than it should.
The American Heart Association (AHA) notes that normal pulmonary blood pressure is 8–20 millimeters of mercury (mm Hg). A doctor may diagnose PAH when a person’s resting pulmonary artery blood pressure
PAH affects approximately
How is it different from pulmonary hypertension?
The AHA states that PAH is a type of pulmonary hypertension (PHT). In both conditions, the heart generates too much force to pump the blood to the lungs, causing high blood pressure in the pulmonary artery.
However, PAH is distinct from other types of pulmonary hypertension because it involves damage to the artery walls in the lungs, which become thick, stiff, or narrow.
How is it different from systemic blood pressure?
Systemic blood pressure is a measure of how forcefully blood flows through other arteries in the body.
A person has hypertension if their blood pressure is 130/80 mm Hg or higher, and doctors may recommend treatment when a person’s blood pressure is consistently 140/90 mm Hg or higher.
Systemic hypertension is more common than PAH. Although both are risk factors for heart disease, PAH is more likely to cause heart failure. Over time, systemic hypertension may damage the heart, causing PAH.
Doctors do not know what causes all cases of PAH. According to the NORD, doctors usually diagnose PAH in people between the age of 30–60 years, and it is more common in females than in males.
Researchers think that female sex hormones may play a role in the development of PAH and that people may be more likely to develop this condition during or after pregnancy.
PAH may also occur due to genetics. In approximately 15–20% of cases, hypertension is genetic.
Changes in a gene called BMPR2 may cause PAH, but this does not explain all cases. Approximately 80% of people who inherit the altered BMPR2 gene do not develop PAH, which suggests that environmental or lifestyle factors interact with the gene to trigger the condition.
In some families, there is a history of PAH even in the absence of this genetic mutation, suggesting that several genes may play a role.
The World Health Organization (WHO) has established five groups of PHT, including PAH, based partially on the suspected cause. PAH falls under group 1, which includes PHT that either has no clear cause or results from genetic factors, the use of certain drugs, or a specific medical condition.
Researchers have linked PAH to several drugs, including:
- dasatinib (Sprycel), which is a leukemia medication
- dexfenfluramine and fenfluramine, which are diet drugs that were once available under the respective brand names Redux and Pondimin (now discontinued)
Health conditions that can lead to PAH include:
- connective tissue disease
- congenital heart disease
- liver disease
- sickle cell disease
The symptoms of PAH typically result from insufficient oxygen in the blood. The first symptom that a person may notice is severe shortness of breath after exertion.
Other possible symptoms include:
- chest pain
- a cough, which may bring up blood
- swelling in the face, feet, ankles, and stomach
A person with advanced PAH may also experience cyanosis, which is the discoloration of the lips, skin, tongue, and other mucous membranes.
Cyanosis can present differently, depending on a person’s skin color. In white people, the skin and lips may appear blue. In Black people, the skin may appear gray or white, and the discoloration may be more evident in the eyes.
The symptoms of PAH are similar to those of other heart conditions, which means that it is not possible to diagnose PAH based on symptoms alone.
During this procedure, a doctor moves a thin tube called a catheter through another blood vessel, such as one in the neck or vein, and into the pulmonary artery. This allows them to see how well and how forcefully blood is flowing. A person is usually awake during the procedure, but doctors may give them medications to help them relax.
Doctors may also perform other tests to rule out additional causes or to assess whether other diseases play a role in PAH. These tests may include:
- blood tests for conditions, such as HIV and autoimmune disorders
- an electrocardiogram, which is a noninvasive test that shows electrical patterns in the heart
- an echocardiogram, which uses sound waves to visualize the heart and view blood flow patterns
- a functional assessment, sometimes called a 6-minute walk test, which assesses how the body responds to physical activity
- lung function and breathing tests
It is important to tell a doctor about all symptoms, as well as any family history of PAH or other heart health conditions.
The Food and Drug Administration (FDA) has approved a number of drugs for PAH.
- Prostaglandins: These medications can help those who have not responded to other types of therapy.
- Endothelin receptor antagonists: These medications can help ease shortness of breath.
- Phosphodiesterase type 5 inhibitors: These drugs may reduce arterial pressure when a person is walking or during other physical activities.
- Vasodilators: These drugs help widen the blood vessels, which can help reduce high blood pressure and ease symptoms.
In addition, the FDA approved riociguat (Adempas) in 2013 specifically for the treatment of PAH. Doctors may also use another FDA-approved drug, selexipag (Uptravi), which may help relax the blood vessels, reducing arterial blood pressure.
Some people may need to receive oxygen therapy as a form of supplemental treatment. In severe cases, an organ transplant may be an option. The individual’s healthcare team may recommend a heart-lung, single lung, or double lung transplant.
Lifestyle and activity adjustments
A person may find that adopting certain lifestyle measures helps improve their symptoms. These may include:
- quitting smoking, if applicable
- consuming a heart-healthy diet consisting of fruits, vegetables, and whole grains
- reaching or maintaining a moderate weight
- staying active
Although physical activity is important for health, a person should avoid lifting heavy weights or doing other activities that cause strain.
PAH is a progressive condition, which means that the condition will worsen over time.
A 2012 evaluation found that in the last 20 years, the survival rate for PAH has improved.
The survival rate refers to the number of people in either a study or treatment group who are still alive for a length of time after receiving a diagnosis. For example, a 5-year survival rate of 50% indicates that 50%, or half, of the people who receive a diagnosis are still alive 5 years afterward.
It is important to remember that these figures are estimates that are based on the results of previous studies or treatment groups. A person can talk with a doctor about how their condition is likely to affect them.
The researchers behind the evaluation reported the following survival rates for individuals with PAH of unknown cause:
- the 1-year survival rate is about 91%
- the 3-year survival rate is about 74%
- the 5-year survival rate is about 65%
- the 7-year survival rate is about 59%
PAH is high blood pressure in the pulmonary arteries, which are the blood vessels that carry blood to the lungs.
Although there is no cure for PAH, treatment can reduce the symptoms and prolong survival. Several clinical trials are underway, and these may eventually lead to more promising treatments.
A person should contact a doctor if they experience any symptoms of PAH, such as fatigue, severe shortness of breath after exertion, and chest pain. The symptoms are similar to those of other conditions that affect the heart, so it is important to get an accurate diagnosis.