Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare form of pulmonary hypertension (PH), a disease associated with abnormally high pressure in the blood vessels of the lungs, caused by the formation of blood clots.
CTEPH also can be referred to as group 4 PH, the World Health Organization classification that defines the type of PH based on the underlying cause.
Unlike other forms of PH, CTEPH can be treated with surgery if diagnosed early enough.
Causes of CTEPH
CTEPH is caused by blood clots that obstruct the pulmonary arteries.
Blood clots are a normal response to bleeding and injuries, as they prevent excessive blood loss, but the body can occasionally produce them without an apparent cause. Specifically, CTEPH develops from a pulmonary embolism, which refers to a blockage in one of the pulmonary arteries in the lungs. Such blockages are due to blood clots that travel from deep veins in the legs or other parts of the body (deep vein thrombosis).
These clots restrict blood flow through the lungs, which causes a localized increase in blood pressure in the pulmonary arteries and a reduction in the level of oxygen transported to the rest of the body. The increase in blood pressure means the heart must work harder to pump blood, which can weaken the heart muscles.
If the condition is left untreated, scar tissue can further narrow the arteries and permanently attach to the blood vessel wall.
Risk factors for CTEPH
CTEPH can occur in people without a history of blood clots in the lungs. However, certain factors are known to increase the risk of developing the disease, including:
- Spleen removal
- Chronic inflammatory disorders such as a bone infection known as bone osteomyelitis, or inflammatory bowel disease
- Thyroid replacement therapy
- A family history of blood clots
- Blood clotting disorders (hypercoagulability)
Women are also more likely to get CTEPH than men.
The symptoms of CTEPH are similar to other types of PH, the most common being shortness of breath and fatigue, due to a decrease in oxygen being circulated around the body. As a result, patients usually have a low tolerance for exercise.
Other symptoms include:
- Chest discomfort
- Coughing up blood
- Swelling in the legs
- Palpitations (pounding heart)
Correctly diagnosing CTEPH is essential, as the underlying cause of PH can determine the available treatment options. The initial diagnosis often relies on the same tests used to diagnose PH, such as echocardiography and right heart catheterization.
A diagnosis of CTEPH is usually reached by ruling out other causes of PH, and through imaging tests to confirm the presence of blood clots. Multiple tests can be carried out for a definitive diagnosis.
A ventilation/perfusion (VQ) scan is one of the most common tests to exclude a CTEPH diagnosis. It measures air and blood circulation by tracking the movement of a tracer through the lungs. A VQ scan that shows no abnormalities normally means the patient does not have CTEPH.
A procedure called pulmonary angiography is a standard way to assess pulmonary embolism. This test typically involves the injection of a dye that can be seen using an X-ray. However, it also can be performed using CT scans or an MRI. These approaches enable physicians to assess blood flow through the pulmonary arteries, confirming whether there are any blockages and if so, pinpointing their location. These tests also can be used to determine whether the patient is suitable for surgery.
Last updated: June 30, 2021
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