Cardiac Radiography > Imaging > Normal Heart Shadow


Normal Heart Shadow

Before delving into the normal cardiac anatomy, it is best to review normal PA and lateral films of the chest as shown below. A more complete approach to chest radiology can be found at University of Virginia Chest X-Ray Website

Normal PA and lateral views of the chest

The cardiac silhouette normally occupies less than 50% of the transverse diameter of the chest on a PA radiograph. If this cardio-thoracic ratio exceeds 50%, the cardiac silhouette may be enlarged. This can result from enlargement of the heart or from pericardial fluid. Non-cardiac causes of an enlarged silhouette include increased mediastinal fat, thoracic cage deformities such as pectus excavatum, and poor inspiration.

The combination of a posteroanterior PA (left) and lateral (right) view of the chest gives the most diagnostic information.

 

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