Flash information
- Measurement
- Cardiothoracic ratio
- Appropriate projection
- Inspiratory PA film
- Usual threshold
- Ratio >0.50 on PA
- Confirmation
- Appropriate cardiac assessment
Definition
Radiographic cardiomegaly is enlargement of the cardiac silhouette, assessed on an appropriate projection.
Examination or reading method
On an inspiratory PA film, divide maximum cardiac width by maximum internal thoracic width.
Morphological description
A ratio above 0.50 suggests enlargement; also describe shape and signs of congestion.
Causes and diagnostic direction
Chamber dilatation, cardiomyopathy, valve disease or pericardial fluid may enlarge the silhouette.
Differential diagnoses
AP projection, poor inspiration and supine position can simulate increased heart size.
Associated findings
Compare films only with comparable technique; echocardiography assesses chambers and pericardium.
Red flags
Dyspnoea, syncope or chest pain warrants assessment; silhouette size alone does not measure cardiac function.
Pitfalls and limitations
The PA ratio does not automatically apply to portable AP films; magnification is a major pitfall.
Take-home message
Check technique before measurement, then correlate apparent enlargement with cardiac assessment.
Sources
- Cardiomegaly - StatPearls - NCBI Bookshelf ↗
- Calculation of the Cardiothoracic Ratio from Portable Anteroposterior Chest Radiography - PMC ↗
Documentary review: 2026-10-12
Media source & rights
- Author
- James Heilman, MD
- Original source
- James Heilman, MD, Cardiomegally.PNG, CC BY-SA 3.0, Wikimedia Commons; conversion WebP et réduction proportionnelle.
- Licence
- CC BY-SA 3.0
- Changes
- Conversion WebP, redimensionnement proportionnel sans recadrage ni annotations ajoutées; EXIF retiré. Dérivé écran proportionnel ≤1280 px, WebP qualité76 ; vignette ≤320 px qualité72. Source acquise et dérivé initial conservés sans modification ; aucune retouche médicale, aucun recadrage.
- Dimensions
- 960 × 869 px
- Check
- 2026-10-11T20:54:35.991796+00:00