Pericardial Effusion

Pathophysiology:  Usually an exudate, but transudative effusions can occur.

Transudative effusions: CHF, renal failure, and hypoproteinemic states.

Exudative effusions: Post-myocardial infarction, viral pericarditis (Coxackie B), other infections especially tuberculosis, collagen vascular diseases (SLE), post trauma (hemopericardium), tumor (eg. lymphoma or metastases to pericardium), bleeding diatheses and coagulopathies with hemopericardium.

CXR Findings:

1. Pericardial fat stripe sign (classic sign):  On lateral film: fluid within pericardial sac (white) outlined on either side by pericardial and endocardial fat (black). This results in a white central stripe outlined by black bands seen along anterior of the right ventricle.

2. enlarged pericardial silhouette

3. may see pericardial calcifications (eg. markers of old infection etc…)

4. globular or flask-like cardiac silhouette in cases of large effusions

Clues:

1. small effusions not seen on CXR will be seen on CT

2. classic “pericardial fat stripe”, rarely seen

3. often the differential diagnosis include causes of an enlarged cardiac silhouette (see “Aunt Sophies”)

4. echocardiography to confirm/quantitate extent of effusion

“Aunt Sophies”:

1. Cardiomyopathies

2. Multiple valve disease, usually due to rheumatic fever, with multiple chamber cardiac enlargement

3. Pericardial cyst, metastases, lymphoma