DDX of characteristic heart shapes

Approach to the DDX of characteristic heart shapes:

  • Egg on a string / egg on its side – transposition of the great arteries – heart appears egg shaped due to abnormal convexity of right atrial border + left atrial enlargement while superior mediastinum appears narrow due to stress-induced thymic atrophy + hyperinflated lung
  • Snowman – total anomalous pulmonary venous return supracardiac – upper half of snowman is dilated superior vena cava on right + left vertical vein on left, lower half of snowman is enlarged right atrium
  • Scimitar – partial anomalous pulmonary venous return – right pulmonary vein drains below diaphragm into inferior vena cava / hepatic veins
  • Boot – tetralogy of Fallot – upward pointing cardiac apex due to right ventricular hypertrophy
  • Gooseneck – AV canal – elongation of the left ventricular outflow tract on angiogram
  • Box-shaped – Ebstein’s anomaly – wall-to-wall heart
  • Water bottle / globular / round – pericardial effusion – large amount of fluid in pericardial space
  • Figure of 3 – coarctation of the aorta – prestenotic dilation ascending aorta / coarctation / post-stenotic dilation descenging aorta
  • Reverse Figure of 3 – coarctation of the aorta on upper GI exam – due to hypoplastic aortic know with dilated post stenotic segment
  • Characteristic heart shapes in patients with congenital heart disease are often due to long standing hemodynamic changes and are therefore less commonly seen today on CXR because patients with congenital heart disease are now diagnosed and treated so early in the disease process