Cardiomegaly

Cardiomegaly means enlargement of the heart. The definition is when the transverse diameter of the cardiac silhouette is greater than or equal to 50% of the transverse diameter of the chest (increased cardiothoracic ratio) on a posterior-anterior projection of a chest radiograph or a computed tomography. It should not be confused with an enlargement of the cardiomediastinal outline. Cardiomegaly is usually a manifestation of another pathologic process and presents with several forms of primary or acquired cardiomyopathies. It may involve enlargement of the right, left, or ventricles or the atria. Many types of cardiomyopathy, such as dilated cardiomyopathy, are characterized by left ventricular dilation and systolic dysfunction, although right ventricular impairment and diastolic dysfunction can also develop.