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

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

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.

References

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