Pulmonary vascular disease
There are two main types of pulmonary vascular diseases: pulmonary embolism and pulmonary hypertension.
Pulmonary embolism occurs due to blood clots which block branches of the arteries in the lungs, often following thrombosis in the veins of the leg or elsewhere.
Pulmonary hypertension 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 heart failure and can be fatal.
People with pulmonary embolism may have no symptoms, or they may experience any of the following:
- Chest pain
- Coughing up blood
- Rapid heart rate
- Rapid breathing
Symptoms of pulmonary hypertension may include:
- Extreme tiredness (fatigue)
- Reduced ability to exercise
- Chest pain
- Coughing up blood
Pulmonary embolism is usually the consequence of a blood clot in the legs or pelvis. This blood clot can break off and travel along the venous system to the pulmonary arteries. Certain groups of people are more at risk of developing blood clots, including the elderly, people who have undergone medical or surgical events that have resulted in long periods of time in bed, people with a previous history of blood clots and those under hormone replacement therapy and oral contraceptive therapy.
The causes of pulmonary hypertension range from a person’s genes, other existing conditions or in some cases, there is no known cause (idiopathic).
There are many different forms of pulmonary hypertension and each is treated very differently. Doctors class the disease into five main groups:
- Pulmonary arterial hypertension (PAH) due to different causes
- Pulmonary hypertension due to left heart diseases
- Pulmonary hypertension due to lung diseases or lack of oxygen (hypoxia)
- Chronic thromboembolic pulmonary hypertension, where the blood vessels are blocked or narrowed by blood clots
- Pulmonary hypertension with an unclear cause or several different triggers
Preventative medicines, such as heparin, can be given to reduce the chance of a blood clot and therefore, pulmonary embolism. Anti-vitamin K drugs can be given after a pulmonary embolism to reduce the risk of blood clotting. Oral anticoagulation drugs, that can be easily prescribed and require less monitoring, are currently in development.
People with long-term lung diseases should be treated with oxygen therapy to prevent the development of pulmonary hypertension. There is no known method of preventing pulmonary arterial hypertension.
Pulmonary embolism is often difficult to diagnose. Doctors rely on identifying symptoms and looking at a person’s medical history, along with routine tests such as a chest x-ray or an electrocardiogram.
Tests to check for the condition also include a blood test, called a D-dimer, to rule out pulmonary embolism and computed tomography (CT) angiography, an imaging technique which uses x-rays, a CT scan and magnetic resonance imaging (MRI).
In an emergency situation, a test called a bedside echocardiography, which uses ultrasound to create images of the heart, can help to diagnose PE. Additionally, ultrasounds can help check if there’s a blood clot in the leg of pelvic veins, which could lead to PE.
Drugs known as anticoagulants can be used to treat pulmonary embolism. Supplementary oxygen can also be provided for people who are struggling to breathe. Thrombolytic drugs, which can dissolve the clots in the pulmonary arteries, are recommended for people who have persistent heart failure and a high risk of PE. If these treatments don’t work, surgery to remove the clot is another option.
Early diagnosis is difficult with pulmonary arterial hypertension (PAH) as many patients have no or few symptoms or just appear unfit. PAH can develop at any age but the average (mean) age of a person diagnosed with PAH is 50 years. Doctors rely on analysis of a person’s symptoms and looking at other factors such as age and existing conditions. Many people go to the doctor late in the course of the disease with signs of right heart failure.
When it is suspected two procedures can be used to help diagnose pulmonary hypertension. The first, known as an echocardiogram, uses sound waves to create a moving picture of the heart. The second, known as right heart catheterisation, is an invasive procedure where a thin tube, known as a catheter, is inserted into the right heart to measure how well it is pumping and into the pulmonary arteries to measure the blood pressure.
Screening programmes that help to identify people most at risk of pulmonary hypertension are a useful way of diagnosing people early.
There is no known cure for pulmonary hypertension but basic drugs such as anticoagulants or oxygen supplementation can help. Patients with pulmonary arterial hypertension can be treated with specific therapies, known as prostacyclins, endothelin receptor antagonists or type 5 phosphodiesterase inhibitors.
If pulmonary hypertension is due to chronic thrombo-embolic disease, a surgical operation known as pulmonary endarterectomy can cure the disease by clearing the clot and scar material in the blood vessels (arteries) of the lungs.
If the condition is severe, lung transplantation may be an option. If pulmonary hypertension is linked to long-term heart or lung diseases, treatment of the underlying condition is recommended.