Pulmonary Hypertension

Background/Epidemiology

• Mean pulmonary artery pressure of ≥25mmHg at rest (measured by right heart catheterisation)
  • Usually with a normal pulmonary artery occlusion (or wedge) pressure (>15mmHg excludes raised pulmonary pressure due to left ventricular failure (a common cause of pulmonary hypertension)
  • Other measurements include the transpulmonary pressure gradient (TPG= PAP-PWP; if >12mmHg, this is suggestive of intrinsic pulmonary disease regardless of a raised PWP)
• Pulmonary Hypertension can be classified as
  • Arterial hypertension
    • Primary (sporadic and familial)- see below
    • Secondary
      • e.g. in connective tissue disease (e.g. limited cutaneous systemic sclerosis; CREST)
      • Congenital (pulmonary shunt systems)
      • Portal hypertension
      • Infection e.g. HIV
      • Drug/toxins
  • Venous
    • Left sided heart disease/failure (including valvular disease)
    • Pulmonary veno-occlusive disease (e.g. chronic/recurrent PE)
  • PH due to lung disease (most common)
    • e.g. COPD, diffuse parenchymal lung disease etc

Primary Pulmonary Hypertension

Epidemiology

• Very rare (2-6/1000,000); predominantly young females (20-30 years old)
  • Most cases seem to be sporadic but (even rarer) familial forms occur (mutations of TGFβ receptor)

Pathology

• Hypertrophy of the vessel wall media/intima, with hyperplasia of endothelial cells (appear as ‘plexiform’ lesions)
  • causes narrowing of the vessel lumen and predisposition to thrombosis; increased vascular resistance and pulmonary hypertension

Presentation

• Often presents with insidious onset breathlessness, chest pain, fatigue, palpitation and syncope
  • Can present very late
• Signs include elevated JVP (may also have a prominent a-wave); parasternal heave (right ventricular hypertrophy); loud pulmonary component of the second heart sound and/or third heart sound
  • It is important to look for signs of an underlying cause (secondary PH) e.g. interstitial lung disease; liver failure; connective tissue disease etc

Investigations

• ECG can show right heart strain pattern (ST depression/T wave inversion in the right leads (V1-3/4 and II, III and avF))
• CXR may show enlarged pulmonary arteries and right ventricular enlargement
• Doppler Echocardiography can provide an estimate of pulmonary pressures although further assessment with right heart catheterisation is often required to guide further therapy.

Management

• Symptomatic/Prophylaxis
  • Diuretic therapy (for right heart failure)
  • Oxygen therapy for patients with chronic hypoxaemia
  • Anticoagulation (warfarin or oral anticoagulation) unless there is a risk of bleeding
  • Vaccination against pneumococcus/influenza
• Treatments
  • Pharmacological
    • High dose calcium channel blockers
    • Prostaglandins e.g. epoprostenol (prostacyclin) or iloprost
    • PDE5 inhibitors e.g. sildenafil
  • Heart-lung transplantation/pulmonary thrombo-endarterectomy in patients with chronic proximal thromboembolic disease