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Snoopy sign

Last revised by Dr Patrick J Rock on 03 Oct 2020

The Snoopy sign is a chest radiographic appearance in pericardial agenesis. It is due to combination of cardiac levoposition (heart shifted to the left), lengthening and flattening of the border of the left ventricle, radiolucency separating the left ventricle and left hemidiaphragm, radiolucency separating the pulmonary artery and aorta, and loss of the right heart border.

History and etymology

The originator of the "Snoopy sign" is not known, however in a paper published in 2005 it is clearly already well-established enough that it is not specifically referenced 2.

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Cases and figures

  • Pericardial agenesis
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