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Pulmonary artery hypertension (PAH)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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In pulmonary arterial hypertension there is an elevated pulmonary arterial pressure (1)

  • pulmonary hypertension is a rare condition defined as mean pulmonary artery pressure >=25 mmHg at rest, measured at right heart catheterisation
    • consequences include a reduced life expectancy

This condition leads to the development of enlarged proximal arteries, right ventricular hypertrophy and dilatation of the right atrium. Changes to the pulmonary arteries are dependent on the cause of the pulmonary hypertension.

A similar clinical pattern to that found in pulmonary hypertension is found in patients with multiple peripheral arterial stenoses. However, the latter condition results in a low arterial pressure in the distal pulmonary bed.

Mutations in the type II bone morphogenetic protein receptor (BMPR2) gene contributes to heritable pulmonary arterial hypertension (2)

The clinical classification is helpful in understanding the different aetiology and determining treatment

  • Group 1 Pulmonary arterial hypertension (PAH)
    • idiopathic PAH
    • PAH associated with connective tissue disease: predominantly seen with scleroderma
  • Group 2 Left heart disease
    • PH associated with left heart dysfunction, systolic, diastolic or valve disease
  • Group 3 Lung disease
    • PH in patients with COPD or interstitial lung disease
  • Group 4 Chronic thromboembolic pulmonary hypertension
  • Group 5 Unclear and multifactorial mechanisms
    • Rare diseases

  • Groups 2 and 3 contain the majority of patients, but in these patients with common medical diseases the underlying condition needs treatment, usually by cardiologists and respiratory physicians respectively. Patients in groups 1 and 4 should be referred for specific treatment by PH specialists in the UK national designated centres

Summary points (1):

  • pulmonary hypertension (PH) is a rare condition, defined by a mean pulmonary artery pressure of > 25 mmHg, that can affect any age group
  • clinical classification (groups 1-5) is based on the aetiology and is useful to determine treatment
  • most patients present with breathlessness on exertion, but signs only appear late in the disease when right heart failure develops
  • patients with suspected pulmonary hypertension should be referred to hospital for investigation and those with pulmonary arterial hypertension (PAH) and chronic thromboembolic disease (CTEPH), groups 1 and 4, should be referred to their regional designated centre for specialist management


  • 1) British Heart Foundation (August 2012). Factfile: pulmonary hypertension
  • 2) Thenappan T, Ormiston ML, Ryan JJ, Archer SL. Pulmonary arterial hypertension: pathogenesis and clinical management. BMJ 2018;360:j5492

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