Pulmonary hypertension

Definition | Classification | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Pulmonary Hypertension (PH) is defined as a mean pulmonary artery pressure (mPAP) of ≥25 mmHg at rest, measured via right heart catheterisation. It is a progressive condition that can lead to right heart failure.

Classification

Pulmonary hypertension is classified into five groups based on the underlying cause:

  • Group 1: Pulmonary arterial hypertension (PAH), often idiopathic or associated with connective tissue diseases.
  • Group 2: PH due to left heart disease (e.g., heart failure or valvular disease).
  • Group 3: PH due to lung diseases or hypoxia (e.g., COPD, interstitial lung disease).
  • Group 4: chronic thromboembolic pulmonary hypertension (CTEPH).
  • Group 5: PH due to unclear or multifactorial mechanisms (e.g., sarcoidosis, sickle cell disease).

Aetiology

Common causes include:

  • Idiopathic: unknown cause, often seen in younger individuals.
  • Secondary:
    • Left-sided heart failure or valvular heart disease.
    • Chronic obstructive pulmonary disease (COPD) or interstitial lung disease.
    • Recurrent pulmonary embolism.
    • Connective tissue diseases such as scleroderma or lupus.

Pathophysiology

Pulmonary hypertension results from increased pulmonary vascular resistance due to:

  • Vasoconstriction: due to hypoxia or endothelial dysfunction.
  • Vascular Remodelling: thickening of pulmonary arterial walls due to proliferation of smooth muscle cells and fibroblasts.
  • Thrombosis: in situ thrombi in pulmonary arteries in conditions like CTEPH.
  • Right Ventricular Overload: leads to right heart failure if untreated.

Risk Factors

  • Family history of pulmonary hypertension.
  • Chronic lung diseases such as COPD or interstitial lung disease.
  • Connective tissue diseases (e.g., scleroderma, lupus).
  • Recurrent pulmonary embolism or history of venous thromboembolism.
  • HIV infection or portal hypertension.

Signs and Symptoms

  • Breathlessness: worsens on exertion.
  • Fatigue: due to reduced cardiac output.
  • Chest Pain: often retrosternal and related to right heart strain.
  • Syncope: particularly during exertion due to reduced cardiac output.
  • Peripheral Oedema: associated with right heart failure.
  • Loud P2 Heart Sound: due to elevated pulmonary pressures.

Investigations

  • Echocardiography (ECHO): a common initial screening tool to assess pulmonary artery pressure and right heart function.
  • Right Heart Catheterisation: this is the gold standard for diagnosing PH and measuring mPAP.
  • ECG: may show right ventricular hypertrophy or right axis deviation.
  • Chest X-ray (CXR): may show enlarged pulmonary arteries or right heart enlargement.
  • Pulmonary Function Tests (PFTs): usually performed to assess for underlying lung disease.
  • Ventilation/perfusion (V/Q Scan): this is performed to detect chronic thromboembolic pulmonary hypertension (CTEPH).
  • Blood Tests:
    • BNP or NT-proBNP: Elevated in right heart strain.
    • Autoimmune screening (e.g., ANA, anti-centromere antibodies) to detect connective tissue diseases.

Management

1. General Measures:

  • Encourage physical activity within tolerance.
  • Advise smoking cessation and vaccination (e.g., influenza, pneumococcal vaccines).
  • Manage underlying conditions (e.g., COPD, heart failure).

2. Pharmacological Treatment:

  • Calcium Channel Blockers (CCBs): for vasoreactive PH confirmed on catheterisation.
  • Endothelin Receptor Antagonists: e.g., bosentan to reduce pulmonary artery pressure.
  • PDE-5 Inhibitors: e.g., sildenafil to promote vasodilation.
  • Prostacyclin Analogues: e.g., epoprostenol for advanced disease.

3. Advanced Therapies:

  • Balloon Atrial Septostomy: palliative procedure to decompress the right heart.
  • Lung Transplantation: for end-stage disease unresponsive to other treatments.

Referral

Consider referral to secondary care in the following scenarios:

  • Specialist Pulmonary Hypertension Centre (if available): for confirmation of diagnosis via right heart catheterisation and advanced management.
  • Respiratory Specialist: for management of underlying lung disease contributing to PH.
  • Cardiology Specialist: for management of left heart disease-related PH.
  • Hospital admission: for patients presenting with decompensated right heart failure or severe hypoxaemia.
 
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