Pulmonary hypertension (PH or PAH)

Pulmonary hypertension (PH or PAH) is an increase in blood pressure in the pulmonary artery, pulmonary vein, or pulmonary capillaries, together known as the Pulmonary Circuit.


Causes, incidence, and risk factors

The right side of your heart pumps blood through the lungs, where it picks up oxygen. Then, the blood returns to the left side of the heart, where it is pumped to the whole body.

When the small arteries (blood vessels) of the lung become narrowed, they cannot carry as much blood. When this happens, pressure builds up. This is called pulmonary hypertension.

The heart needs to work harder to force the blood through the vessels against this pressure. Over time, this causes the right side of the heart to become larger. Not enough blood flows to the lungs to pick up oxygen. At this point, heart failure involves the right side of the heart. This is called cor pulmonale.

Pulmonary hypertension may be caused by:

  • Autoimmune diseases that damage the lungs, such as scleroderma and rheumatoid arthritis

  • Birth (congenital) defects of the heart

  • Blood clots in the lung (pulmonary embolism)

  • Congestive heart failure

  • Heart valve disease

  • HIV infection

  • Low oxygen levels in the blood for a long time (chronic)

  • Lung disease, such as COPD or pulmonary fibrosis

  • Medicines (for example, certain diet drugs)

  • Obstructive sleep apnea

In many cases the cause is unknown. In this case, the condition is called idiopathic pulmonary arterial hypertension (IPAH). It used to be called primary pulmonary hypertension (PPH).

IPAH is rare. It affects more women than men.

If pulmonary hypertension is caused by a known medicine or medical condition, it is called secondary pulmonary hypertension.

SYMPTOMS include:

  • Shortness of breath,
  • Dizziness,
  • Fainting,
  • Ankle and leg swelling
  • Bluish color of the lips or skin (cyanosis), all of which are exacerbated by exertion.
  • Pulmonary hypertension can be a severe disease with a markedly decreased exercise tolerance and heart failure.

Normal PAP (measured invasively by right heart catheterization) has a peak systolic value of 18 to 25 mmHg. Accurate quantitative measures of right heart pressures are difficult to obtain by non-invasive techniques. Echo measurements are estimations. Therefore, preference is given to invasive values, but they are rarely available.

Widespread use of echocardiograms has led to the observation of mild elevations (40-50mmHg range) in RVSP/PAP. The World Health Organization (WHO) recommends that, in asymptomatic individuals, the echocardiogram be repeated in six months. In symptomatic individuals, right heart catheterization is indicated to confirm the finding of elevated PAP.

A physical examination is performed to look for typical signs of pulmonary hypertension.

Further procedures are required to confirm the presence of pulmonary hypertension and exclude other possible diagnoses. These generally include pulmonary function tests; blood tests to exclude HIV, autoimmune diseases, and liver disease; electrocardiography (ECG); arterial blood gas measurements; X-rays of the chest (followed by high-resolution CT scanning if interstitial lung disease is suspected); and ventilation-perfusion or V/Q scanning to exclude chronic thromboembolic pulmonary hypertension. Clinical improvement is often measured by a "six-minute walk test", i.e. the distance a patient can walk in six minutes. Stability and improvement in this measurement correlate with better survival.

Treatment is determined by the cause of PH and the clinical findings.