Pulmonary Hypertension

Symptoms

Pulmonary hypertension is raised blood pressure within the pulmonary arteries, which are the blood vessels that supply the lungs.

It is a serious medical condition that can damage the right side of the heart, making the heart less efficient at pumping blood around the body and getting oxygen to the muscles.

Symptoms of pulmonary hypertension include:

• shortness of breath 
• fatigue (tiredness) 
• feeling faint or dizzy
• chest pain (angina)
• a racing heartbeat (tachycardia)
• leg swelling 

Pulmonary hypertension is a potentially serious health condition that can lead to heart failure.

Symptoms of pulmonary hypertension include:

• shortness of breath 
• fatigue (extreme tiredness)
• dizziness
• feeling faint
• chest pain (angina)
• a racing heartbeat (tachycardia)
• leg swelling

Your symptoms may get worse when you exercise, which can limit your ability to take part in physical activities.

As pulmonary hypertension progresses, carrying out everyday activities may also become difficult. If your condition starts impact on your everyday life, it can affect your quality of life and may lead to depression. Visit your GP if you feel depressed so they can recommend appropriate treatment.

If you have a type of pulmonary hypertension known as pulmonary arterial hypertension (PAH), you may not experience any symptoms until the condition is quite advanced. 

Heart failure

Untreated pulmonary hypertension can lead to heart failure, where your heart struggles to pump enough blood around your body. As well as shortness of breath and tiredness, heart failure can also cause:

• swelling in the legs, ankles and feet (oedema) 
• waking up in the middle of the night gasping for breath (paroxysmal nocturnal dyspnoea) 
• a persistent cough 
• nausea (feeling sick) 
• lack of appetite 
• weight loss
• confusion or difficulty concentrating 

What happens in pulmonary hypertension

In a healthy person, blood travels through the pulmonary arteries from the right-hand side of the heart, picking up oxygen when it reaches the lungs.

Oxygen-rich blood from the lungs returns to the left-hand side of the heart, where it is pumped around the body to the muscles, where the oxygen is needed.

During exercise, the demand for oxygen increases so the heart beats quicker and the pulmonary arteries usually widen to let more blood flow through to the lungs.

However, if you have pulmonary hypertension, the walls of your pulmonary arteries are thick and stiff, making it difficult for them to expand to allow more blood through. Alternatively, your pulmonary arteries may be blocked by blood clots which can also hinder blood flow.

The reduced blood flow makes it difficult for the right-hand side of your heart to pump blood through the arteries, which means that this part of the heart has to work harder.

If the right-hand side of your heart has to continually work harder, it may gradually become weaker. This will make it less efficient at pumping blood and can lead to heart failure.

Pulmonary hypertension is caused by changes to the pulmonary arteries, which are blood vessels that carry blood from your heart to your lungs.

The walls of your pulmonary arteries can become stiff and thickened, or the blood vessels may get blocked by blood clots. This makes it difficult for your heart to pump blood through these arteries, which increases pressure inside them, leading to pulmonary hypertension.

There can be many different reasons for the changes to your arteries. The World Health Organization (WHO) has classified pulmonary hypertension into five different types, depending on the underlying cause. They are:

• pulmonary arterial hypertension (PAH)
• pulmonary hypertension associated with left heart disease
• pulmonary hypertension associated with lung disease and hypoxia 
• pulmonary hypertension due to blood clots
• pulmonary hypertension due to other causes 

These are described below.

Pulmonary arterial hypertension (PAH)

Pulmonary arterial hypertension (PAH) is caused by problems with the smaller branches of the pulmonary arteries. In PAH, these changes are usually the main problem, rather than another condition.

As the pulmonary arteries are directly affected, they can be treated immediately, whereas in other types of pulmonary hypertension the underlying cause must be treated first.

PAH can be further divided into specific subtypes which are described below. 

Idiopathic PAH

Idiopathic means the cause is unknown. If tests cannot find an underlying reason for your condition, you may be diagnosed with idiopathic PAH. This is an extremely rare condition affecting only about two people in every million each year. 

Inherited PAH

Some cases of PAH run in families. A particular genetic mutation (a change in one of the genes you inherit from your parents) is sometimes thought to cause PAH. There may be a family history of the condition in up to 10% of idiopathic PAH cases.

PAH associated with other conditions

Other conditions or treatments associated with PAH include:

• connective tissue diseases that affect the structure or composition of your body tissue, such as scleroderma (a disorder that causes hardening of the skin)
• congenital heart problems, such as a hole in the heart 
• portal hypertension - a condition where blood pressure inside the liver is abnormally high, which causes veins to become swollen
• HIV - about 1 in 200 people with HIV will develop PAH
• certain medications or drugs - such as fenfluramine (a medication no longer available) and amphetamines, which are a type of illegal drug
• thyroid gland disorder
• sickle cell disease and related conditions  
• glycogen storage disorders (glycogen is a carbohydrate that produces short-term energy)

PAH can also be associated with rare conditions that affect your blood vessels such as:

• pulmonary veno-occlusive disease - a condition that causes high blood pressure in the lungs
• pulmonary capillary hemangiomatosis - where tiny blood vessels (capillaries) grow within the lungs, causing blockages

Persistent pulmonary hypertension of the newborn

It is estimated that persistent pulmonary hypertension of the newborn affects around 2 in every 1,000 newborn babies. 

Conditions that may also be associated with persistent pulmonary hypertension of the newborn include:

• severe pulmonary hypoplasia - where your baby’s lungs are seriously underdeveloped  
• hypoglycaemia - an abnormally low level of glucose in the baby’s blood  
• sepsis - a life-threatening illness caused by very severe infection
• meconium aspiration syndrome - where a newborn baby breathes in a mixture of amniotic fluid (the fluid that surrounds the baby in the womb) and meconium (their first faeces), which can block their airways

Left heart disease

Pulmonary hypertension is sometimes associated with diseases that affect the left side of the heart (the side that pumps blood around the whole body apart from the lungs). The left side of the heart consists of:

• the left atria (upper chamber)
• the left ventricle (lower chamber) 
• the aortic and mitral valves - one-way valves that allow blood to flow through the heart in the correct direction

As blood flows through the pulmonary arteries to the lungs and then to the left side of the heart, any problem could have a backwards effect on this circuit and affect the pulmonary arteries. This in turn could cause pulmonary hypertension. 

Up to 60% of people with a condition that causes severe left ventricle dysfunction have pulmonary hypertension. Almost all people with a severe mitral valve condition, and nearly two thirds of those with a severe aortic valve condition have pulmonary hypertension.

Lung disease and hypoxia

Pulmonary hypertension is also sometimes associated with lung diseases or hypoxia (a shortage of oxygen in the body). This includes:

• chronic obstructive pulmonary disease (COPD) - a term that describes a number of lung diseases, such as emphysema, where people have trouble breathing; up to half of people with advanced COPD may also have pulmonary hypertension, although it is usually mild  
• interstitial lung disease - a group of lung disorders that cause scarring of the lung tissue, which makes it difficult to get enough oxygen into your body; about a third of people with interstitial lung disease may have pulmonary hypertension 
• sleep-disordered breathing - conditions that affect breathing while you are in deep sleep, such as obstructive sleep apnoea (OSA)

These types of conditions can restrict the amount of oxygen able to get into your lungs and therefore into your blood. A low level of oxygen in the blood causes the pulmonary arteries to constrict (get narrower). As these vessels are narrower, the blood is squeezed into a smaller space, which increases the blood pressure and results in pulmonary hypertension.

Blood clots

Pulmonary hypertension is sometimes the result of a blood clot that causes narrowing or a blockage in the pulmonary arteries or veins.

A blood clot that blocks one of the blood vessels that supply your lungs is known as a pulmonary embolism. After having a pulmonary embolism, up to 2 in 100 people may have pulmonary hypertension.

Other causes

Other, less common causes of pulmonary hypertension include: 

• sarcoidosis - a condition that causes inflammation of different organs, including the lungs and lymph nodes
• histiocytosis X - a rare condition that causes scarring (granulomas) and air filled cysts, predominantly in the lungs
• compression of the blood vessels in the lungs - for example, due to a tumour (growth)

Diagnosing pulmonary hypertension

Correctly diagnosing pulmonary hypertension can sometimes take time because its symptoms are similar to many other heart and lung conditions.

However, pulmonary hypertension can be a serious condition so it is important you visit your GP if you experience symptoms.

They will ask about your symptoms and medical history. Tests, including an echocardiogram (a type of ultrasound scan) and an electrodardiogram (tests the electrical rhythm of your heart) can be used to see how well your heart and pulmonary arteries are working.

Pulmonary hypertension can be difficult to diagnose because symptoms are often similar to other conditions that affect the heart or lungs.

This means there can sometimes be a long delay before a correct diagnosis is made. 

However, as pulmonary hypertension can be serious, it is important you visit your GP if you have symptoms such as breathlessness and fatigue (extreme tiredness). Your GP will ask about:

• your symptoms and how they affect your life
• your family history (some types of pulmonary hypertension run in families)
• whether you are currently taking any medication 
• whether you have any other medical conditions

Testing

You may have several tests, either to diagnose pulmonary hypertension, or to identify an underlying condition that may be causing it. The initial tests, described below, may be carried out by your GP or a hospital specialist.

Echocardiogram

An echocardiogram is a type of ultrasound scan that can determine how well your heart is working.

It uses high-frequency sound waves to create an image of an area inside your body, such as your heart. The image can be used to estimate the pressure in your pulmonary arteries.

Electrocardiogram

An electrocardiogram (ECG) records your heart's rhythm and electrical activity.

Small, metallic discs called electrodes are stuck to your arms, legs and chest and connected with wires to an ECG machine.

Every time your heart beats, it produces tiny electrical signals. The ECG machine traces these signals onto paper.

Chest X-ray

An X-ray is an imaging technique that uses high-energy radiation to highlight abnormalities in bones and other types of tissue.

A chest X-ray can look for other causes of your symptoms, such as scarring in your lungs, which can also cause shortness of breath.

A chest X-ray can also check whether your heart is larger than normal. Pulmonary hypertension makes the right-hand side of your heart work harder, causing it to become enlarged.

Lung function tests

Lung function tests, also known as breathing tests, assess how well your lungs work.

The tests measure how quickly you are able to move air in and out of your lungs, how much air they can hold and how well they transfer oxygen into your blood and remove carbon dioxide from it.

During the tests, you will be asked to breathe into a lung function machine. The data collected will help diagnose any underlying lung conditions.

Exercise tests

Exercise tests involve carrying out some form of exercise while checking your symptoms.

For example, you may be asked to walk on a treadmill or up and down a corridor for six minutes while your heart rate, blood pressure and oxygen levels are monitored. This can help determine whether there are any underlying causes of your symptoms.

Ventilation-perfusion scan

A ventilation-perfusion scan measures the amount of air and the blood flow in your lungs. This can be used to look for blood clots in your blood vessels that may be causing pulmonary hypertension.

Blood tests

A sample of blood may be taken and tested to rule out other possible conditions, such as thyroid and liver disease.

Confirming the diagnosis

The above tests may suggest pulmonary hypertension is present, but the diagnosis can only be confirmed by measuring your blood pressure in:

• the right ventricle (lower chamber) of your heart, which pumps blood to your lungs
• your pulmonary arteries, which carry blood from the right side of your heart to your lungs

Your blood pressure is measured using a procedure called right-heart catheterisation.

Right-heart catheterisation

In right-heart catheterisation, a thin flexible tube called a catheter is inserted into a vein in your neck, arm or groin. The catheter is then fed through into the right side of your heart and into your pulmonary arteries.

As well as measuring blood pressure, the catheter can be used to measure the:

• amount of blood the right-hand side of your heart is pumping out to your lungs 
• pressure your heart must work against to get blood to your lungs (pulmonary vascular resistance)
• amount of oxygen in the blood that returns to your heart

If the pressure in your pulmonary arteries is above a certain level, you will be diagnosed with a particular type of pulmonary hypertension.

If the diagnostic tests described above reveal an underlying cause, you will be diagnosed with a particular type of pulmonary hypertension. If no cause is found, you will be diagnosed with idiopathic pulmonary arterial hypertension.

Classifying pulmonary hypertension

As part of your diagnosis, your condition will be classified depending on its severity. This will help determine the best treatment for you.

Pulmonary hypertension is classified into four types where: 

• ordinary physical activities do not cause any symptoms
• ordinary physical activities cause symptoms, such as chest pain or fatigue, but you have no symptoms when resting 
• even slight physical activities, such as moving your arms, cause symptoms, but you have no symptoms when resting 
• you have symptoms when resting, which are increased with any type of physical activity

Treating pulmonary hypertension

Pulmonary hypertension is a serious condition that usually gets progressively worse. Left untreated, it may cause heart failure which can be fatal.

If pulmonary hypertension is caused by an existing condition, such as heart disease, lung disease or a blood clot, the underlying condition should be treated first. In some cases, this can prevent the pulmonary arteries being permanently damaged.

If you have a type of pulmonary hypertension known as pulmonary arterial hypertension (PAH), you will be referred to a centre that specialises in treating the condition. There are currently seven specialist centres in England and one in Scotland. They are:

• Great Ormond Street Hospital (for children), London
• Hammersmith Hospital, London
• Royal Brompton Hospital, London
• Royal Free Hospital, London
• Papworth Hospital NHS Trust, Cambridgeshire
• Royal Hallamshire Hospital, Sheffield
• Freeman Hospital, Newcastle
• Golden Jubilee National Hospital, Glasgow

A number of medications can be used to treat PAH and other types of pulmonary hypertension. To start with, anticoagulant medicines and diuretics may be recommended. Later on, a number of more specialist medications may be prescribed.

Outlook

Symptoms of pulmonary hypertension, such as breathlessness, can significantly affect your quality of life as you may be unable to continue with your regular activities. Therefore, it is important treatment is started as soon as possible to improve your symptoms.

With the introduction of new medicines, people are now able to live longer with PAH. One study found about two-thirds of people lived for more than five years after their diagnosis. 

Your outlook will depend on how quickly the condition is diagnosed, how advanced your symptoms are and whether you have another underlying health condition.