Double density sign (left atrium)

Dr Craig Hacking and A.Prof Frank Gaillard et al.

The double-density sign, also known as the double right heart border, is seen on frontal chest radiographs in the presence of left atrial enlargement, and occurs when the right side of the left atrium pushes behind the right cardiac shadow, indenting the adjacent lung and forming its own distinct silhouette 1-3

If large enough, the left atrium can actually reach beyond the border of the right atrium; this is known as atrial escape 3. The right superior pulmonary vein can lead to a similar appearance 1

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Article information

rID: 20322
System: Cardiac
Section: Signs
Synonyms or Alternate Spellings:
  • Double right heart border
  • Double contour sign
  • Double contour sign of left atrial enlargement
  • Right retrocardiac double density

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Cases and figures

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