Patient Presentation
A resident was discussing a newborn who had been transferred from an outside facility for cyanosis. "The baby even had a snowman sign on his x-ray. I've only read about that because usually we get an echo so fast and already know what is happening. They think that baby was already having problems in utero so you could see the snowman so quickly after birth," he said. He went on, "it was also a good chance to review all the cyanotic congenital heart problems and we went over some other examples with the radiologist too."
Discussion
Total anomalous pulmonary venous return causes snowman sign on a chest x-ray. The pulmonary veins fail to connect normally to the left atrium. Alternate pathways direct flow to the right atrium and then across an atrial communication. The admixture of blood at the atrial level and the right to left atrial shunt result in the cyanosis. It may present at birth because of obstruction to the pulmonary veins.
"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 [chest x-ray] because patients with congenital heart disease are often diagnosed and treated so early in the disease process."
Learning Point
Examples of characteristic congenital heart diseases on chest x-ray include:
Box-shaped - Ebstein's anomaly - heart takes up most of the thoracic diameter, there is "wall-to-wall" heart
Boot - Tetralogy of Fallot - upward pointing cardiac apex due to right ventricular hypertrophy
Egg on a string / egg on its side - Transposition of the great arteries - the egg shape is caused by abnormal convexity of the right atrial border and left atrial enlargement, with the superior mediastinum appearing narrow due to stress-induced thymic atrophy and hyperinflated lungs
Figure of 3 - Coarctation of the aorta - there is prestenotic dilation of the ascending aorta, then coarctation, then post-stenotic dilation of the descending aorta; Reverse Figure of 3 occurs on the upper GI exam and is caused by hypoplastic aortic knob with dilated post stenotic segment
Snowman - Total anomalous pulmonary venous return - upper half of snowman is caused by the dilated superior vena cava on right and left vertical vein on left, lower half of snowman is caused by the enlarged right atrium
Scimitar - Partial anomalous pulmonary venous return - the right pulmonary vein drains below diaphragm into inferior vena cava and/or hepatic veins
Water bottle / Round - Pericardial effusion - a large amount of fluid in pericardial space. This obviously is not a congenital malformation, but can be seen with them as well or is due to other conditions
Questions for Further Discussion
1. What are the common cyanotic congenital heart diseases and when do they present?
A review can be found here
2. What are the common acyanotic congenital heart diseases and when do they present? A review can be found here
3. What causes pericarditis? A review can be found here
Related Cases
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for this topic: Congenital Heart Defects
To view current news articles on this topic check Google News.
To view images related to this topic check Google Images.
To view videos related to this topic check YouTube Videos.
Gupta SK. Clinical Approach to a Neonate with Cyanosis. Indian J Pediatr. 2015;82(11):1050-1060. doi:10.1007/s12098-015-1871-7
Dasgupta S, Kelleman M, Slesnick T, Oster ME. Cardiomegaly on chest radiographs as a predictor of heart disease in the pediatric population. Am J Emerg Med. 2020;38(5):855-859. doi:10.1016/j.ajem.2019.06.045
D'Alessandro, M. Differential diagnosis of characteristic pediatric heart shapes. PediatricImaging.org. Published October 6, 2019. Accessed June 12, 2023. https://pediatricimaging.org/ddx/ddx-of-characteristic-heart-shapes/
Author
Donna M. D'Alessandro, MD
Professor of Pediatrics, University of Iowa
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