Pulmonary hypertension is literally high blood pressure in the lungs. It typically occurs when arteries carrying blood to the lungs become narrow or blocked, causing a backup of pressure. Over time, this increased pressure puts severe stress on the heart as it strains to pump blood through the blood vessels of the lungs. The result is weakening and eventual failure of the heart.
Pulmonary hypertension is a serious problem that may go undetected in the early stages, as in Julia’s case, or confused with other heart and lung disorders such as asthma, emphysema and congestive heart failure.
When the disorder occurs without an identifiable cause, it’s known as primary pulmonary hypertension. Only about 300 to 500 new cases of primary pulmonary hypertension are diagnosed each year.
In the majority of cases, pulmonary hypertension is an effect of another medical condition such as heart or lung disease, blood clots in the lungs, obstructive sleep apnea, congenital heart defects, scleroderma, HIV infection or liver disease.
Many cases in recent years have been linked to chronic use of cocaine, amphetamines or appetite suppressants such as fenfluramine (fen-phen), which was taken off the market in 1997.
When something else is causing the pulmonary hypertension, the first step is treating the underlying cause. But this will not necessarily ease the hypertension, particularly if it’s progressed past the beginning stages. Generally speaking, there’s no cure for pulmonary hypertension, but recent advances in medication therapy are making it possible for patients to ease symptoms and delay the progress of the disease.
How It Develops
As blood completes its circuit after delivering oxygen and nutrients to the cells of the body, it passes into the lower right chamber (right ventricle) of the heart from which it is pumped into the lungs through the pulmonary artery. In the lungs, the blood releases carbon dioxide and takes in oxygen before traveling to the lower left chamber (left ventricle) to be pumped back to the cells of the body.
Normally, blood pressure in the lungs is relatively low–about 14 millimeters of mercury (mm HG) when a person is at rest. Anything that impedes flow can cause a buildup of pressure, and pulmonary hypertension is defined as systolic lung blood pressure greater than 25 mm Hg at rest or 30 mm Hg during exercise.
This can happen because of constriction of blood vessels or, more commonly, changes in the endothelial cells that line blood vessels and the formation of extra tissue that narrows or blocks the blood vessels.
One of the first symptoms of pulmonary hypertension is shortness of breath, which is also a symptom of asthma and numerous other lung and heart disorders. When the breathlessness is fairly constant, as in Julia’s case, a doctor may start exploring possible causes.
As it strains to pump blood through the lungs, the lower right chamber of the heart eventually becomes weakened and enlarged, compromising the pumping action. Heart failure is frequently an effect of pulmonary hypertension.
Weakened pumping action, either by the right or left ventricle leads to backup of fluids, swelling of the feet and ankles, fatigue and difficulty exercising or even moving around. Shortness of breath becomes progressively worse, and some patients eventually require oxygen for daily activities.
Other serious complications include the formation of a blood clot (pulmonary embolism) or the buildup of fluids (pulmonary edema) in the lungs–either of which is life-threatening.
In the past, treatment usually involved managing symptoms with diuretics, anticoagulants and high doses of calcium channel blockers, which help relax muscles in the walls of blood vessels.
Often used to treat regular hypertension, calcium channel blockers such as amlodipine, dilitiazem and nifedipine are effective in only about 25 percent of patients with pulmonary hypertension and, at the doses needed, can cause serious side effects.
Over the past decade or so, several other medications have emerged which appear to be more effective.
Prostacyclins are drugs that have a powerful effect in dilating blood vessels. These drugs are administered by continuous infusion either intravenously or under the skin and require the patient to carry a small pump.
A newer form of the drug, iloprost, is more convenient; it can be inhaled through a nebulizer every three hours or so. It is also more expensive.
Endothelin receptor antagonists such as bosentan (Tracleer) come in pill form. They work by reversing the action of endothelin, a substance that causes the walls of blood vessels to constrict. These drugs can cause liver complications and must be monitored monthly.
Sildenafil, the active ingredient in Viagra, is also used to treat pulmonary hypertension. The dose needed is much larger than that ordinarily required for erectile dysfunction, and side effects must be monitored.
Patients are usually advised to stay as active as possible, reduce stress, stop smoking, maintain a healthy weight, eat a healthy diet and avoid air travel and visits to high altitudes. Women of child-bearing age should avoid becoming pregnant.
When medications are ineffective, the final option is lung or lung/heart transplantation. This decision is made after a thorough evaluation at a transplantation center.
With new treatment options, many patients are able to live fairly normal lives for a number of years. Early diagnosis, however, is crucial, and patients should seek out doctors who have training and experience treating pulmonary hypertension.
Tana N Kaefer, PharmD
