Pericardial effusions occur when excess fluid collects in the pericardial space (a normal pericardial sac contains approximately 30-50 mL of fluid).
There is no single demographic affected, as there are many underlying causes of a pericardial effusion.
Clinical presentation of pericardial effusions does not relate so much to the size of the effusion but rather the speed at which the fluid has accumulated, as slow gradual accumulation allows the pericardium to stretch and accomodate much larger volumes of fluid 4.
Regardless of volume, symptoms relate to impaired cardiac function due to intrapericardial pressure approximating intracardiac pressure leading to impaired filling of low pressure chambers, particularly the right atrium.
Dyspnoea and reduced exercise tolerance will be early signs, progressing to severe impaired cardiac output and death in severe cases (e.g. cardiac tamponade).
- post-myocardial infarction: Dressler syndrome
- connective tissue disorders
- post surgical / trauma
- pulmonary arterial hypertension 7
- a very small pericardial effusion can be occult on plain film
- there can be globular enlargement of the cardiac shadow giving a water bottle configuration
- lateral CXR may show a vertical opaque line (pericardial fluid) separating a vertical lucent line directly behind sternum (epicardial fat) anteriorly from a similar lucent vertical lucent line (pericardial fat) posteriorly; this is known as the Oreo cookie sign 5
- widening of the subcarinal angle without other evidence of left atrial enlargement may be an indirect clue 2
- a differential density sign at cardiac borders has been suggested 9, but its specificity is limited
- usually requires greater than 200 mL of pericardial fluid to become radiographically visible
Echocardiography is the method of choice to confirm the diagnosis, estimate the volume of fluid and most importantly assess the haemodynamic impact of the effusion.
The accepted thickness of a normal pericardium, measured on CT scans and on MR images, is often taken at 2 mm 6.
CT makes the diagnosis extremely easy, but is usually obtained to try and clarify the cause of an effusion rather than to confirm the diagnosis. Pericardial effusions are a frequent incidental finding in unwell hospitalised patients.
Fluid density material is seen surrounding the heart. Careful inspection of the region is necessary to ensure that no invasive mass can be identified.
Depth of the effusion can be used to estimate the likely volume of fluid, provided the fluid is relatively evenly spread throughout the pericardium (global effusion) 4. Clearly this does not apply to localised effusions.
- <5 mm: 50-100 mL
- 5-10 mm: 100-250 mL
- 10-20 mm: 250-500 mL
- >20 mm: >500 mL
Treatment and prognosis
If small, asymptomatic and clinically not-suspect then conservative management is usually favoured.
If large, symptomatic or there is clinical concern of the underlying cause (e.g. infection, malignancy) then pericardiocentesis can be performed to drain the fluid. A Seldinger technique is employed, usually under ultrasound/echocardiographic guidance, to insert a drain into the pericardial space 4.
In cases where effusions are recurrent and symptomatic (e.g. malignancy) then pericardial fenestration can be performed.
- haemopericardium: has higher attenuation on CT and often a different clinical context
- cardiomegaly: can sometimes mimic an effusion
- 1. Lin E, Escott E, Garg K et-al. Practical differential diagnosis for CT and MRI. Thieme Medical Pub. (2008) ISBN:1588906558. Read it at Google Books - Find it at Amazon
- 2. Chen JT, Putman CE, Hedlund LW et-al. Widening of the subcarinal angle by pericardial effusion. AJR Am J Roentgenol. 1982;139 (5): 883-7. AJR Am J Roentgenol (abstract) - Pubmed citation
- 3. Arthur, Stephen; Beeharry-Panray, Gailash; FitzGerald, Jonathan; Loke, Ian. Hypothyroidism presenting with recurrent pericardial tamponade - BMJ Case Reports. doi:10.1136/bcr.03.2009.1674
- 4. Zamorano JL, Bax JJ, Rademakers FE. The ESC Textbook of Cardiovascular Imaging. Springer Verlag. (2010) ISBN:1848824203. Read it at Google Books - Find it at Amazon
- 5. Weissman NJ, Adelmann GA. Cardiac imaging secrets. Elsevier Health Sciences. (2004) ISBN:1560535156. Read it at Google Books - Find it at Amazon
- 6. Wang ZJ, Reddy GP, Gotway MB et-al. CT and MR imaging of pericardial disease. Radiographics. 2003;23 Spec No : S167-80. doi:10.1148/rg.23si035504 - Pubmed citation
- 7. Shimony A, Fox BD, Langleben D et-al. Incidence and significance of pericardial effusion in patients with pulmonary arterial hypertension. Can J Cardiol. 2013;29 (6): 678-82. doi:10.1016/j.cjca.2012.04.009 - Pubmed citation
- 8. Imazio M, Adler Y. Management of pericardial effusion. Eur. Heart J. 2012;34 (16): 1186-97. doi:10.1093/eurheartj/ehs372 - Pubmed citation
- 9. Tehranzadeh J, Kelley MJ. The differential density sign of pericardial effusion. Radiology. 1979;133 (1): 23-30. doi:10.1148/133.1.23 - Pubmed citation