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Pulmonary hypertension

Pulmonary hypertension (PH) is caused by high blood pressure in the pulmonary arteries, which carry blood from the heart to the lungs. It can damage the right part of the heart making it unable to efficiently circulate blood around the body. It can lead to right heart failure and can be fatal. 

Last Update 18/04/2024

What is pulmonary hypertension?


PH is caused by high blood pressure in the blood vessels called the pulmonary arteries. They are responsible for carrying blood from the heart to the lungs. The walls of the pulmonary arteries become thick and stiff and cannot expand as well to allow blood through. 

The increased resistance to the blood flow through the pulmonary arteries can damage the right part of the heart which pumps blood to the pulmonary arteries leading to right-sided heart failure and can be fatal. PH can occur on its own, but it is more common in people who have another heart or lung condition. This makes the diagnosis and treatment complicated. It often requires input from professionals in different areas of medicine such as lung health, heart health, radiology and thoracic surgery. 

Types of pulmonary hypertension


PH includes many different types of the disease. It can be categorised into five groups, based on different causes. 

Group 1: Pulmonary arterial hypertension (PAH) 

PAH is caused by high pressure in the blood vessels that carry blood from the heart to the lungs. This happens due to changes in the structure of the pulmonary arteries which are thick or blocked. You can find out more about PAH on our dedicated page 

In PAH the increased pressure in the blood vessels is caused by blockages in the small arteries in the lung for a variety of reasons. PAH may be linked to the genes that we inherit from our parents. Other forms of PAH can be induced by drugs or toxins or associated with other diseases such as liver disease, schistosomiasis, caused by a parasitic worm that lives in fresh water in subtropical and tropical regions, and autoimmune diseases such as scleroderma, congenital heart disease, human immunodeficiency virus (HIV) infection. When no cause is identified, PAH is labelled as idiopathic. 

Group 2: Pulmonary hypertension associated with left heart disease 

This is the most common form of pulmonary hypertension. People with PH associated with left heart disease have problems with the valves or muscle (myocardium) on the left side of the heart or issues with how the heart is pumping. Their arteries are not as thick as people with PAH, but there can be a build-up of blood as the left heart is unable to work quickly enough to pump the blood returning from the lungs. 

Group 3: Pulmonary hypertension associated with lung diseases and/or hypoxia 

This group includes people who experience PH because of a long- term lung disease or low oxygen levels. This includes conditions such as chronic obstructive pulmonary disease (COPD), where the airways are narrower, and pulmonary fibrosis where there is scar formation in the lung causing difficulty with breathing. The destruction of the lung parenchyma together with low blood oxygen level results in increased pressure in the pulmonary artery.  

Group 4: Chronic thrombo-embolic pulmonary hypertension (CTEPH) 

This type of PH is caused by a chronic blood clot in the lungs. It occurs when your body cannot dissolve the blood clot and it leaves scar tissue in the blood vessels. This blocks the arteries making it harder for the heart to pump blood through them. This type of PH is unique as it can be treated by surgery to remove the blood clots. Other treatments could include a procedure to widen the pulmonary arteries with a balloon, known as balloon pulmonary angioplasty, or PH medication. 

Group 5: Pulmonary hypertension with unclear and/or multi-factorial mechanisms 

This group refers to PH that happens alongside multiple conditions or where it is unclear what is causing PH. It includes PH linked with sarcoidosis, sickle cell anaemia and certain metabolic disorders. 

As there is a lack of research and evidence on how to treat this group, treatment is usually focused on the underlying condition linked with PH. 

Symptoms of pulmonary hypertension


Symptoms can vary from person to person but could include: 

  • Shortness of breath when doing activities or when bending forwards, 
  • Tiredness (fatigue) 
  • Feeling light-headed, faint, or dizzy 
  • A quick heartbeat or a feeling that the heartbeat is unusual or uncomfortable  
  • Swelling in the legs, ankles, feet or stomach or weight gain from holding more water in the body. 

Diagnosing pulmonary hypertension


Shortness of breath and other symptoms of PH may develop slowly. They usually get worse as the disease progresses.  

If your doctors suspect that you have PH, they will look at your symptoms and how you are feeling. Echocardiography is the preferred screening test, which estimates indirectly the pressure in the pulmonary arteries and the probability that you have PH. When PH is suspected on the basis of echocardiography results, PH diagnosis will be confirmed by direct measure of the pressure in the pulmonary arteries by right-heart catheterization, which is the gold-standard for diagnosis of PH. 

There are two main goals at this stage: 

  • To make sure that anyone who is thought to have a severe form of PH is referred to a specialist PH centre with multidisciplinary teams 
  • To check for other underlying conditions, such as lung or heart conditions and to classify PH precisely. This will help to find out the kind of PH you have to ensure you receive the right management.

Treatment of pulmonary hypertension


Treatment for PH aims to lower the risk of the disease for each person. Full treatment plans will be put together through shared decision making with healthcare professionals.  

General treatments and lifestyle changes could include: 

Treatment options differ depending on the type of PH a person has. Our lay guideline on diagnosing and treating pulmonary hypertension includes a full overview of the recommended approach to treatments.  

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