Pulmonary artery disease is a condition in which the blood vessels that carry blood from your heart to your lungs become narrowed, stiffened, or blocked, forcing your heart to work much harder to push blood through. The most well-known form is pulmonary arterial hypertension (PAH), where pressure inside these arteries rises above 20 mmHg (normal is 10 to 20 mmHg). Globally, an estimated 192,000 people live with PAH, and women are affected nearly twice as often as men.
What Happens Inside the Arteries
In a healthy lung, blood flows easily through the pulmonary arteries, picks up oxygen, and returns to the left side of the heart to be pumped throughout the body. In pulmonary artery disease, the walls of the small pulmonary arteries undergo structural changes that obstruct this flow. Smooth muscle cells multiply and coat the inner walls in thick layers. In more advanced cases, the vessels develop complex, maze-like formations that trap blood and prevent it from reaching the parts of the lung where oxygen exchange happens.
As the arteries narrow, pressure builds. The right side of the heart, which pumps blood into the lungs, has to generate more and more force to keep blood moving. Over months or years, this extra workload causes the right ventricle to enlarge and eventually weaken, a process called right heart failure.
Five Clinical Groups
Pulmonary hypertension is classified into five groups based on the underlying cause. Understanding which group applies shapes how the condition is treated.
- Group 1: Pulmonary arterial hypertension (PAH). The disease originates in the small pulmonary arteries themselves. Causes include genetic mutations, connective tissue diseases like scleroderma, HIV infection, congenital heart defects, certain drugs and toxins, or no identifiable cause (idiopathic).
- Group 2: Left heart disease. Conditions like heart failure or valve problems cause blood to back up into the lungs, raising pulmonary pressure indirectly.
- Group 3: Lung disease or low oxygen levels. COPD, pulmonary fibrosis, sleep apnea, and other conditions that reduce oxygen availability can drive pulmonary artery pressure upward.
- Group 4: Chronic blood clots. Old clots that never fully dissolve can physically obstruct the pulmonary arteries, a condition called chronic thromboembolic pulmonary hypertension (CTEPH).
- Group 5: Unclear or multiple causes. Blood disorders, metabolic conditions, chronic kidney failure, and other systemic diseases fall here.
Causes and Risk Factors
The most common genetic driver of PAH is a mutation in the BMPR2 gene, which provides instructions for a protein that helps regulate cell growth in blood vessel walls. When this gene malfunctions, the smooth muscle cells lining the pulmonary arteries can grow unchecked. Over 300 different mutations in this gene have been identified. In families with a history of PAH, a BMPR2 mutation is found in about 82% of cases. Even among people diagnosed with no family history, 11% to 40% carry one of these mutations.
Having the mutation doesn’t guarantee you’ll develop the disease. Only 20% to 30% of people who carry a BMPR2 mutation ever develop PAH, which means other factors, such as hormones, inflammation, or environmental exposures, play a role in triggering it.
Non-genetic causes vary by group. Chronic lung diseases damage the small blood vessels over time. Left-sided heart failure raises pressure passively by pushing fluid backward into the pulmonary circulation. Unresolved blood clots create physical blockages. Some appetite-suppressing drugs and recreational stimulants have also been linked to PAH.
Symptoms From Early to Advanced Stages
The hallmark symptom is shortness of breath during physical activity, and it tends to worsen gradually. In the early stages, you may only notice it during exercise or climbing stairs. Other early symptoms include reduced stamina, chest tightness, heart palpitations, and occasional lightheadedness or fainting spells. Less commonly, people experience a persistent cough, hoarseness, or coughing up small amounts of blood.
Because these symptoms overlap with many common conditions like asthma, being out of shape, or anxiety, pulmonary artery disease is frequently misdiagnosed or caught late. The average time from symptom onset to diagnosis can stretch well beyond a year.
As the disease advances and the right side of the heart begins to fail, a different set of symptoms emerges. Swelling in the ankles, legs, and abdomen becomes noticeable. The veins in the neck may appear swollen and visibly pulsating. Skin can take on a bluish tint, especially in the fingers and lips, and extremities feel cold to the touch. Dizziness and fatigue become constant rather than occasional, and shortness of breath occurs even at rest.
How It’s Diagnosed
Diagnosis typically starts with noninvasive tests. An echocardiogram (an ultrasound of the heart) can estimate pulmonary artery pressure and show whether the right ventricle is enlarged or struggling. CT scans, lung function tests, and blood work help identify underlying causes like lung disease or blood clots.
The definitive test is right heart catheterization. A thin, flexible tube is threaded through a vein, usually in the neck or groin, into the right side of the heart and the pulmonary artery. This directly measures the pressure inside the pulmonary arteries, the pressure in the heart chambers, how much blood the heart pumps per minute, and the resistance the blood encounters in the lung vessels. A mean pulmonary artery pressure above 20 mmHg confirms pulmonary hypertension. Additional pressure readings help doctors determine which of the five groups is responsible.
Treatment Approaches
Treatment depends heavily on the underlying cause. Group 2 patients need their heart failure or valve disease addressed. Group 3 patients benefit from treating the lung disease and supplemental oxygen. Group 4 patients with clot-related disease may be candidates for surgery.
Medications for PAH (Group 1)
Three signaling pathways in the body regulate how pulmonary arteries relax and constrict, and approved medications target each one. One class of drugs mimics a natural substance called prostacyclin, which widens blood vessels and prevents cells from clumping. Another class blocks a protein called endothelin that causes arteries to tighten. A third class works through the nitric oxide pathway, helping the smooth muscle in artery walls relax. Many patients take medications from two or even all three pathways simultaneously, a strategy called combination therapy that has improved outcomes significantly over the past two decades.
Surgery for Chronic Blood Clots
For Group 4 patients whose clots are located in the larger, more accessible pulmonary arteries, a procedure called pulmonary endarterectomy can physically remove the clot material. It is a complex surgery, but outcomes are strong: patients who survive the procedure have a five-year survival rate around 90%, compared to a 60% to 70% one-year death rate for symptomatic patients left untreated. For clots that are too deep in the arteries for surgery, balloon procedures and targeted medications offer alternatives.
Survival and Outlook
Before modern treatments became available in the 1980s, only about 36% of people with PAH survived five years. Current therapies have dramatically improved that picture. Recent data from specialized centers show one-year survival around 96% and five-year survival near 87%, though these numbers vary considerably depending on the specific cause. Patients whose PAH is linked to congenital heart disease tend to fare better, with five-year survival around 74%. Those with connective tissue diseases like scleroderma face a harder road, with five-year survival closer to 43%.
Early detection makes a meaningful difference. Patients diagnosed before the right side of the heart starts failing respond better to treatment and maintain a higher quality of life. Risk scoring tools now help doctors tailor treatment intensity to each patient’s profile, escalating therapy quickly for those at higher risk rather than taking a wait-and-see approach.