Pericardial Effusion

by | 20 May, 2020

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Pericardial effusion is the collection of fluid within the pericardial sac. It usually occurs as a complication of pericarditis or myocarditis. Cardiac tamponade may occur, which is cardiogenic shock due to compromised ventricular filling resulting from the pericardial effusion. Slowly accumulating pericardial effusions are less likely to tamponade than rapid fluid collection; the pericardial sac is able to stretch and expand in slow fluid accumulation, allowing ventricular function to be maintained.


Similar causes to acute pericarditis.
  • Viral: coxsackie B, echovirus. Usually painful but short-term
  • Post-myocardial infarction: occurs in 20% of patients in the first few fays after an MI. May also occur later in Dressler’s syndrome
  • Uraemic: due to irritation by accumulating toxins
  • Malignant: usually produces a haemorrhagic effusion. Usually from bronchial cancer, breast cancer and Hodgkin’s lymphoma.
  • Trauma
  • Connective tissue disorders e.g. Rheumatoid arthritis, systemic lupus erythematosus
  • Bacterial: can occur in septicaemia and post-operatively
  • Tuberculous
  • Fungal e.g. histoplasmosis
Tamponade Bleeding and effusions are the commonest causes of tamponade. Haemorrhage from trauma, aortic dissection, surgery or coronary artery perforation during angiography can lead to blood accumulating in the pericardial sac.

Clinical features

Effusions are difficult to detect clinically. Features of pericarditis are the dominant presentation.


  • Soft and distant heart sounds
  • Obscured apex beat
  • Friction rub


  • Right ventricular failure e.g. raised JVP, peripheral oedema
  • Left ventricular failure e.g. pulmonary oedema


  • ECG: low-voltage QRS complexes. Pulsus alternans in tamponade
  • Chest x-ray: large globular heart
  • Echocardiography: diagnostic for pericardial effusions
  • Pericardiocentesis: if TB, malignant or purulent effusions are suspected

Pericardial fluid colour

  • Fibrinous
  • Serous (uraemic): straw-coloured with high protein content
  • Haemorrhagic: usually malignant or traumatic
  • Purulent: septicaemia


Most pericardial effusions are asymptomatic and resolve spontaneously. Treat the underlying cause is sufficient in most cases. Symptomatic patients may benefit from pericardiocentesis.


Pericardiocentesis is required if there is tamponade, which is symptomatic compression of the heart resulting in cardiogenic shock. The needle is inserted medial to the cardiac apex or below the xiphoid process under echocardiographic guidance to reach the pericardial sac.


Pericardial effusion occur secondary to other conditions and most are asymptomatic. Effusions may reaccumulate, especially in malignant causes.


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