Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Cardiomegaly chest x ray
Introduction
Overview
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
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
Image courtesy of C. Michael Gibson MS. MD
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
References
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]