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Pulmonary Hypertension

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Overview

Pulmonary hypertension (PH) is characterised by increased blood pressure in the arteries of the lungs and the presence of increased pulmonary vascular resistance. This can cause strain on the right side of the heart, leading to right ventricular hypertrophy and failure.

Classification and Risk Factors

WHO Classification system

The World Health Organisation has produced a system for classifying PH based on cause and associations:

  • Group I – idiopathic or associated with connective tissue disorders (e.g. systemic lupus erythematosus)
  • Group 2 – secondary to left heart disease/valvular disease/restrictive cardiomyopathy
  • Group 3 – secondary to chronic lung disease/environmental hypoxaemia
  • Group 4 – due to chronic thrombotic/embolic disease
  • Group 5 – metabolic disorders/systemic disorders/haematological disease/other causes

Epidemiology

  • Idiopathic PH is rare – prevalence is around 50 per 1,000,000
  • PH is more common in severe respiratory/cardiac disease

Presentation

Pulmonary hypertension presents insidiously with progressive breathlessness and fatigue. Features may be:

Investigations

All patients

  • Chest X-ray:
    • Rules out other lung diseases
    • May show enlarged pulmonary artery or hilar vessels
  • ECG:
    • May show right ventricular hypertrophy (RVH) or right axis deviation
  • Echocardiography:
    • Assess right ventricular function and estimate pulmonary arterial pressure
  • Right heart catheterisation:
    • Directly measures pulmonary pressure and confirms the diagnosis

Diagnosis

Pulmonary hypertension is diagnosed if the mean pulmonary arterial pressure is >25 mmHg at rest or >30 mmHg with exercise.

Management

All patients

  • 1st-line: manage the underlying cause
  • Consider sildenafil (phosphodiesterase-5 inhibitor, also known as Viagra), bosentan (endothelin-A receptor antagonist)
  • Cardiopulmonary transplantation is considered in severe cases

Complications

  • Right ventricular hypertrophy and right ventricular failure
  • Peripheral oedema
  • Hepatic congestion
  • Exertional syncope
  • Cardiac arrest

Prognosis

  • Idiopathic PH left untreated has a median survival of 2-3 years
  • The mean survival of people with right heart failure or severe PH is around 12 months

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