Understanding Pulmonary Hypertension

Pulmonary hypertension, or PH, is a simplified name for a complex health problem: high blood pressure in the lungs. The name comes from pulmonary, or having to do with the lungs, and hypertension, which means high blood pressure. It is a disease that affects people of all ages and ethnic backgrounds.

One thing that most types of PH have in common is that they are often not recognized until they are quite advanced. As a result, many people may have PH without knowing it, so higher awareness and earlier diagnosis can help people get earlier treatment. There are several different kinds of PH, and below we will describe them, and explain how they are different.

Understanding the different types of PH

PH starts when the small vessels that supply blood to the lungs constrict, or tighten up. It is more difficult for blood to get through to the lungs, and the heart must pump harder to overcome the resistance. As time passes, scarring (or fibrosis) of the vessels makes them stiffer and thicker, and some may be completely blocked. The extra stress causes the heart to enlarge and become less flexible. Less and less blood is able to flow out of the heart, through the lungs, and into the body, and more and more symptoms start to show.

In 1988, the World Health Organization (WHO) sponsored a meeting of PH specialists with the goal of creating a standardized system for defining different kinds of PH. The committee proposed that the disease be divided into the following five categories of pulmonary hypertension:

   1. Pulmonary arterial hypertension (PAH)

  • The pulmonary artery is the large vessel that carries blood from the heart into the lungs so it can pick up oxygen. Most cases of PH affect this artery and the hundreds of tiny blood vessels that branch off from it. This category includes two types of PH:
  • Primary pulmonary hypertension (PPH) can occur at random, without any apparent cause. Other times, the disease can be inherited; it is estimated that at least 10 percent of PPH cases occur in families where at least one other person has had it.
  • PAH related to other causes appears to be similar to PPH, but is actually associated with exposure to toxins or the effects of other diseases. These can include:
    • Collagen vascular disease (scleroderma, lupus, rheumatoid arthritis)
    • Congenital heart disease
    • Chronic liver disease
    • Human immunodeficiency virus (HIV)
    • Use of diet drugs such as Fenfluramine or Dexfenfluramine
    • Use of cocaine, methamphetamine, or other street drugs
    • Persistent pulmonary hypertension of the newborn

  2. Pulmonary hypertension associated with disorders of the respiratory system

  • Emphysema
  • Interstitial lung disease
  • Sleep apnea
  • Chronic exposure to high altitude

  3. Pulmonary hypertension due to chronic thrombotic or embolic disease

  • Blood clots in pulmonary arteries
  • Pulmonary embolism (caused by clot, tumor, or foreign matter in the lungs)
  • Sickle cell disease

  4. Pulmonary hypertension due to disorders directly affecting the pulmonary blood vessels

  • Inflammatory diseases such as Schistosomiasis or Sarcoidosis
  • Pulmonary capillary disease

  5. Pulmonary venous hypertension (PVH)

  • Is caused by disease of the left side of the heart, such as mitral valve disease or a poorly performing left ventricle. This can cause increased pulmonary artery pressures, but rarely leads to severe PAH.

Confirming a diagnosis

PH is often not diagnosed in a timely manner because its early symptoms can be confused with those of many other conditions. Some of the symptoms of PH include:

  • Breathlessness or shortness of breath
  • Feeling tired all the time
  • Dizziness, especially when climbing stairs or upon standing up
  • Fainting - often the symptom that brings people to their doctors
  • Swollen ankles and legs
  • Chest pain, especially during physical activity

To establish a diagnosis of PH, a series of tests are performed that show how well a person's heart and lungs are working. These tests may include


  • Echocardiogram
  • Electrocardiogram (ECG)
  • Right heart catheterization
  • Six-minute walk test
  • Assessment of function in tasks of daily living

If these tests show that a person definitely has PH, other kinds of diagnosis tests may be ordered to aid in identifying the cause, including:

  • A computed tomography (CT or CAT) scan to rule out a pulmonary embolism or lung disease
  • A pulmonary function test to rule out obstructive lung disease
  • A formal sleep study to rule out sleep apnea
  • Laboratory tests to rule out hepatitis, collagen disease, HIV, or other conditions
  • When no cause can be found, the diagnosis is primary pulmonary hypertension (PPH)

Associated Diseases

Many Pulmonary Hypertension patients are diagnosed with PH in association with one or more related conditions.  Research shows that up to 30% of Schleroderma patients, 20-40% of sickle cell patients and one out of every 200 HIV patients develop at least mild PH.

Other conditions commonly associated with PH included mixed connective tissue disease, congenital heart disease (CHD) chronic obstructive pulmonary disease (COPD), hereditary hemorrhagic telangiectasia (HHT), sleep apnea, liver disease and lupus.  PH has also been linked to the use of certain drugs and toxins, including Fenfluramine, Dexfenfluramine and methamphetamines.