Cardiomegaly chest x ray

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Overview[edit | edit source]

Cardiomegaly is easily visualized on chest x ray. Cardiomegaly is traditionally defined as a cardiothoracic ratio that is more than 0.5 on a PA film. Other findings on chest x ray can help to determine the specific chamber that is contributing most to the enlargement of the heart.

Chest X Ray[edit | edit source]

• Cardiomegaly is traditionally defined as an increase in the cardiothoracic ratio to be > 0.5 on a PA film. To calculate the thoracic ratio, the width of the cardiac silhouette is divided by the width of the entire thoracic cage.
• If the heart is viewed on an AP film, the heart can appear to be artificially enlarged because the X ray beam moves from anterior to posterior direction and therefore the heart which lies anterior is magnified.

  • Postero Anterior (PA) Projection: The adult heart is 12 cm from base to apex and 8-9 cm in transverse direction.
  • Lateral Projection: The adult heart is 6 cm in the antero posterior (AP) direction.

X-ray Findings for Left Ventricular Enlargement[edit | edit source]

• Left heart border is displaced leftward, inferiorly, or posteriorly
• Rounding of the cardiac apex

X-ray Findings for Left Atrial Enlargement[edit | edit source]

• Double density sign: Occur when the right side of the left atrium pushes into the adjacent lung.
• Convex left atria appendage: usually reflect prior rheumatic heart disease.
• Splaying of the carina
• Posterior displacement of the left main stem bronchus on lateral radiograph
• Superior displacement of the left main stem bronchus on frontal view
• Posterior displacement of a barium filled esophagus

X-ray Findings for Right Ventricular Enlargement[edit | edit source]

• Frontal view

• Rounded left heart border
• Uplifted apex

• Lateral view

• Filling of the retrosternal space
• Rotation of the heart posteriorly

X-ray Findings for Right Atrial Enlargement[edit | edit source]

• On a frontal view, the right atrium is visible because of its interface with the right middle lobe.
• Subtle and moderate right atrial enlargement is not accurately determined on plain films because there is normal variability in the shape of the right atrium.

References[edit | edit source]

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