What is pulmonary hypertension?
Primary pulmonary hypertension (PPH) is a rare lung disorder in which the blood pressure in the pulmonary artery rises far above normal levels for no apparent reason. The pulmonary artery is a blood vessel carrying oxygen-poor blood from the right ventricle (one of the heart's pumping chambers) to the lungs. In the lungs, the blood picks up oxygen, then flows to the heart's left side, where the left ventricle pumps it to the rest of the body through the aorta.
Hypertension is a medical term for abnormally high blood pressure. Normal average pulmonary artery pressure is about 14 mm Hg at rest. In patients with PPH, the average blood pressure in the pulmonary artery is greater than 25 mm Hg at rest and greater than 30 mm Hg during exercise. This abnormally high pressure (pulmonary hypertension) is linked with changes in the small blood vessels in the lungs. These changes increase resistance to blood flowing through the vessels. This increased resistance puts a strain on the right ventricle, which now must work harder than usual to move enough blood through the lungs.
What are the causes?
The exact cause of PPH is not known but there may be one or more causes. There is a low incidence of PPH, which makes learning more about the disease extremely difficult. It is thought that in most people who develop primary pulmonary hypertension, the blood vessels are very sensitive to certain factors that trigger this disease to develop.
What are the symptoms?
The first symptom is often fatigue or tiredness. Other symptoms include:
- Difficulty in breathing, dizziness and even fainting
- Swelling in the ankles or legs,
- Bluish discoloration of the lips and skin, and chest pain more often occur later in the disease
One of the great difficulties in treating PPH is that the diagnosis is often delayed due to the slowly progressive and insidious onset of the symptoms
How is it diagnosed?
Significant advances in PPH treatment over the past decade have markedly affected the survival and quality of life for people with this disease. The optimal medical and/or surgical treatment for patients with PPH depends upon a thorough diagnosis and evaluation. The diagnosis includes a right heart cardiac catheterisation. In this procedure the doctor places a thin, flexible tube (a catheter) through an artery or vein in the patient's arm, leg or neck, then threads it into the right ventricle and pulmonary artery. This is the only way to measure the pressure in the pulmonary artery and find out what medical therapy is appropriate for a given patient.
What is the treatment?
Doctors can choose from a variety of drugs that help lower blood pressure in the lungs and improve heart performance in many patients. Patients with PPH respond differently to the different medications that dilate or relax blood vessels and no single drug is consistently effective in all patients. During the course of the disease, the amount and type of medicine also may have to be changed. At present, about one-quarter of patients can be treated with calcium channel-blocking drugs given orally.
Other medications classes like sildenafil, ambrisentan and epoprostenol can also be used to treat pulmonary hypertension.
Anticoagulants, for example, can decrease the tendency of the blood to clot, thus permitting the blood to flow more freely. Diuretics reduce the amount of fluid in the body, further reducing the amount of work the heart has to do. Some patients also require supplemental oxygen delivered through nasal prongs or a mask if breathing becomes difficult. Some patients need oxygen around the clock.
Transplantation (heart-lung or lung) is reserved for patients who do not respond to medical therapy. The decision whether a patient requires heart-lung transplantation or lung transplantation is made after a thorough evaluation.
What is the prognosis?
Despite the complexity of some of the various medical therapies, accurate, early diagnosis and initiation of treatment can save the lives of patients with PPH. Treatment is long term and patients often have to take medications for years.