Pulmonary Hypertension

Nearly 50 million Americans have high blood pressure or “hypertension.” It occurs when blood travels through the body’s arteries at a pressure too high for good health. A far less common type of high blood pressure affects only the arteries in the lungs. Known as pulmonary hypertension, it is a serious illness that becomes progressively worse and eventually may prove fatal.

Pulmonary hypertension begins when the tiny arteries in the lungs become narrowed or blocked. This causes increased resistance to blood flow in the lungs, which in turn raises pressure within the pulmonary arteries. As pressure builds, the heart’s right ventricle must work harder to pump blood through the lungs, eventually causing the heart muscle to weaken and sometimes fail completely.

Unexplained or primary pulmonary hypertension (PPH) is a rare, and it causes the blood pressure in the pulmonary artery to rise far above normal levels. 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.

In the United States, an estimated 500 to 1,000 new cases of PPH are diagnosed each year. The greatest number of cases is reported in women between the ages of 20 and 40. However, men and women in all age ranges—as well as very young children—can develop PPH. An extremely wide variability in the severity of PPH is found in patients. Evaluating, accurately diagnosing, and treating the condition is very complex. For these reasons, patients with symptoms that suggest PPH require thorough evaluation at a medical center with expertise and experience in treating it.

What Causes PPH?

Although the exact cause is unknown, PPH can probably be attributed to one or more causes. The low incidence makes learning more about the disease extremely difficult. Studies of PPH have also been difficult. It is currently thought that most people who develop PPH have blood vessels that are very sensitive to certain factors that trigger development of the disease. For example, people with Raynaud syndrome seem more likely to develop PPH. Additionally, appetite suppressants, cocaine, and HIV are all believed to trigger constriction, or narrowing, of the pulmonary artery.

If the disease exists by itself and has no underlying cause, it is called pulmonary arterial hypertension. Other forms of pulmonary hypertension are caused by another condition or disease, such as emphysema, pulmonary blood clots (chronic thromboembolic pulmonary hypertension), or congenital heart disease. Successful treatment of the underlying disease may decrease or cure the pulmonary hypertension. Chronic thromboembolic pulmonary hypertension is a type of pulmonary hypertension that is often misdiagnosed. The correct diagnosis of this condition is important because it is very treatable with surgery.

Symptoms

• Fatigue or tiredness. Many patients think that they’re simply “out of shape.”
• Difficulty breathing, dizziness, and fainting spells can occur.
• Swelling in the ankles or legs, bluish discoloration of the lips and skin, and chest pain 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.

Diagnosis

Hemodynamic right heart catheterization is necessary to measure pulmonary artery pressure, to confirm the severity and type of pulmonary hypertension, and to determine the best approach to treatment. The test accurately measures pulmonary artery pressure and resistance, as well as blood flow through the lungs. During the catheterization, pulmonary angiography can be used to take x-ray pictures of the pulmonary blood vessels (in the lungs). Several additional noninvasive tests can help identify whether or not pulmonary hypertension is contributing to the patient’s problem, and these include echocardiography, pulmonary function tests, perfusion lung scan, CT angiogram, and magnetic resonance imaging (MRI).

Treatment

Pulmonary arterial hypertension is a relatively rare disease with no cure. However, specialized treatment can lower pulmonary pressures, reduce symptoms, increase the capacity to be active, and prolong lifespan. Medicines used to treat pulmonary arterial hypertension include prostacyclin analogues, endothelin receptor antagonists, phosphodiesterase-5 inhibitors, high-dose calcium channel blockers, anticoagulants, diuretics, and oxygen. Many drugs for treating pulmonary hypertension have strong, serious side effects. The dosage must be carefully set and monitored to avoid dangerous consequences.

Patients with PPH respond differently to the different medications that dilate or relax blood vessels, and one particular drug is not effective for all patients. Because individual reactions vary, a variety of different drugs must be tested before chronic or long-term treatment begins. During the course of the disease, the amount and type of medicine may also need to be changed. To determine which medicine works best for a particular patient, doctors evaluate different medicines during cardiac catheterization.

Because another disease may be causing the PPH, the underlying disease must be treated. Successful treatment of the underlying disease may decrease or cure PPH. If the underlying disease cannot be cured, the pulmonary hypertension may have to be treated directly, using many or all of the treatment methods used in pulmonary arterial hypertension.

Transplantation (heart-lung or lung) is reserved for patients who don’t respond to medical therapy.

Prognosis

Despite the complexity of the various medical therapies, accurate, early diagnosis and initiation of treatment have saved the lives of many patients with PPH. With optimal medical and/or surgical therapy, patients can often return to a virtually normal lifestyle, including running a household, attending school, and participating in physical activities. Much of the research and development of treatments have focused on PPH. However, these same treatments are now being evaluated in many patients with pulmonary hypertension due to other causes, such as congenital heart disease or disorders such as scleroderma or systemic lupus erythematosus.


Resources

American Heart Association www.americanheart.org/presenter.jhtml?identifier=4752
Mayo Clinic www.mayoclinic.org/pulmonary-hypertension/index.html