Cardiomegaly is a catch-all term to refer to enlargement of the heart, and should not be confused with causes of enlargement of the cardiomediastinal outline, or enlargement of the cardiac silhouette.
On this page:
Pathology
Etiology
There are many etiologies for cardiomegaly:
hypertension (with left ventricular hypertrophy)
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valvular disease
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drugs (numerous drugs are cardiotoxic)
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pulmonary disease (leading to right-sided enlargement)
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systemic disease/physiology
normal “athletic” heart
pregnancy
renal failure
anemia
post-radiation
Radiographic features
In most cases, merely 'eye-balling' a chest x-ray will be sufficient in detecting cardiomegaly (as the heart is either clearly normal in size or clearly abnormally enlarged). In equivocal cases, the cardiothoracic ratio (CTR) can be easily calculated on an erect PA chest x-ray. The CTR measures the width of the cardiac silhouette and the thoracic cavity;
Traditionally, a ratio greater than 0.5 has been considered to be abnormal 1. However a CTR of >0.55 has been shown to be more specific for cardiac chamber enlargement 1,2.
Specific cardiac chamber enlargement can be recognized by cardiac contour changes, new or different interfaces with adjacent lung, and/or displacement of adjacent mediastinal structures. These are discussed separately:
Differential diagnosis
other causes of an enlarged cardiac silhouette
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