*What cardiac condition has the classic CXR that shows a “snowman” or “figure-8” silhoutte? What occurs in this condition? What causes the snowman silhouette?
Total Anomalous Pulmonary Venous Return (Supracardiac)TAPVR occurs when the pulmonary veins go either to the right atrium or to other systemic veins that then drain into the RA. The majority of infants present early with tachypnea and FTT. The snowman findings occurs when the pulmonary veins drain into the left superior vena cava and blood flows into the innominate vein, where it finally enters the heart through the normal right superior vena cava.
The cardiac condition that has the classic CXR (chest X-ray) that shows a “snowman” or “figure-8” silhouette is “total anomalous pulmonary venous return” (TAPVR).
TAPVR is a congenital heart defect in which all the pulmonary veins that normally carry oxygen-rich blood from the lungs back to the heart don’t connect to the left atrium (LA) as they should, instead they connect to the right side of the heart or to an improper location. Because of that, the oxygen-rich blood cannot get to the body through the left ventricle as it should.
The snowman or figure-8 silhouette is formed because the enlarged right atrium (RA) is connected to the left atrium by a narrow, upright “snowman”-like structure made up of the enlarged vertical vein via which oxygenated blood from the lungs returns to the heart.
The extra blood volume in the RA causes it to enlarge and produce this classic CXR appearance. The diagnosis of TAPVR is confirmed by echocardiography, magnetic resonance imaging (MRI), or cardiac catheterization.
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