Cardiomegaly chest x ray

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

Overview

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

• 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

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

Cardiomegaly.
Image courtesy of C. Michael Gibson MS. MD

Cardiomegaly in a patients after mitral valve replacement. AP view. Image courtesy of RadsWiki

Cardiomegaly in a patients after mitral valve replacement. Lateral view. Image courtesy of RadsWiki.

X-ray Findings for Left Atrial Enlargement

• 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.

Double density sign

Double density sign

X-ray Findings for Right Ventricular Enlargement

• 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

• 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.