Pulmonary Hypertension

  • Basics

    Pulmonary hypertension is a disorder in which the blood pressure in the vessel that leads from the heart to the lungs (pulmonary artery) rises to higher-than-normal levels Figure 01. High blood pressure in the pulmonary artery puts added strain on the heart, which must then work much harder to pump blood throughout the body. Under the strain, the heart may eventually fail completely.

    Sometimes, the cause of pulmonary hypertension remains unknown. In these very rare cases, the disorder is referred to as primary pulmonary hypertension (PPH). In the U.S., only about 500 to 1,000 people are diagnosed each year with PPH. Although PPH can strike anyone at any age, it occurs most often in young adults—primarily women between the ages of 20 and 40.

    When a cause for pulmonary hypertension can be identified, such as emphysema or a birth defect in the heart, the disorder is known as secondary pulmonary hypertension (SPH). SPH is believed to be relatively common, but is underdiagnosed. Many cases are mild and cause little or no illness; however, when severe, SPH can be serious. For that reason, there are no reliable estimates of how many people develop the condition each year. It is known, however, that enlargement of the right ventricle of the heart (cor pulmonale)—the heart condition that develops when pulmonary hypertension goes untreated—is the third most common type of heart disorder in people over 50 years of age.

    Certain diet drugs have been linked to pulmonary hypertension. The link to diet drugs was first recognized in 1967 when there was an epidemic of pulmonary hypertension in Europe among people who had used the appetite suppressant aminorex fumarate (Menocil). In 1997, two diet drugs—fenfluramine hydrochloride (Pondimin) and dexfenfluramine hydrochloride (Redux)—were taken off the market after they, too, were associated with an increased risk for pulmonary hypertension.

    Pulmonary hypertension has no cure. Early diagnosis and effective treatment can, however, make it possible for some people to extend and improve their lives.

    Click to enlarge: The circulatory system

    Figure 01. The circulatory system

  • Causes

    Pulmonary hypertension appears to be triggered by changes to the cells lining the small blood vessels of the lungs. These changes cause the muscles around the blood vessels to constrict, narrowing the vessels. Because of the narrowed vessels, the heart must pump harder to get blood to the lungs, increasing pressure within the artery. This increased effort thickens and damages the artery, and enlarges one of the chambers of the heart muscle (the right ventricle). Eventually, the right side of the heart may become so weakened that it fails completely.

    In cases of primary pulmonary hypertension, doctors simply do not know what causes the damage to the lung’s small blood vessels. Research suggests, however, that family genetics, an immune system disease, or exposure to chemicals may be involved.

    With secondary pulmonary hypertension, the source of the damage to the lung’s small blood vessels can be traced to a known cause. Emphysema and chronic bronchitis--strongly linked to cigarette smoking and together known as chronic obstructive pulmonary disease (COPD)—are among the more common causes of SPH. Other causes of SPH include:

    • birth defects in the heart
    • liver disease
    • connective tissue disease (such as lupus or scleroderma)
    • sleep apnea (a serious condition in which breathing is repeatedly interrupted during sleep)
    • HIV infection
    • use of illicit drugs

    Certain diet drugs also have been linked to pulmonary hypertension. The problem was first recognized in 1967 when there was an epidemic of pulmonary hypertension in Europe among people who had used the appetite suppressant aminorex fumarate (Menocil). In 1997, two diet drugs—fenfluramine (Pondimin) and dexfenfluramine hydrochloride (Redux)—were taken off the market after they, too, were associated with an increased risk for pulmonary hypertension.

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