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Transposition of the great arteries (TGA) is the most commonly missed prenatal cardiac diagnosis, despite excellent imaging modalities. Fetal Heart Program director Jack Rychik, MD, presents guidelines to help clinicians accurately identify TGA by fetal echocardiogram.
Jack Rychik: My name is Jack Rychik. I'm the director of the Fetal Heart Program and professor of pediatrics at The Children's Hospital of Philadelphia. I'd like to show you some images that will help demonstrate how to identify transposition of the great arteries. This is an exercise that I think you should perform in all of your patients on a regular basis to become familiar with identification of the origins of the vessels as they arise from the heart.
First we're going to start with looking at the normal heart with the apex up on top. We start with a four-chamber view. The right ventricle circled in red, is thickened and hypertrophied. And we're identifying the vessels as they come off each of their respective chambers. Notice that the great vessels, as they arise from the heart, cross each other in space as we sweep from the apex towards the head. Compare that to this case of transposition of the great arteries where both great vessels arise from the heart in parallel. The aorta in red, the pulmonary artery in blue. Again, compare that to the normal where the two vessels cross each other in space as we sweep towards the head. And now the patient with transposition of the great arteries: both vessels arise in parallel from the heart.
Another way would be to look at the heart and lung axis. Here we have the right ventricle on top and the left ventricle on the bottom. And again, the two vessels cross each other in space. The red is the aorta, the blue is the pulmonary artery, each arising from their respective ventricles. The vessels cross in space, aorta and then pulmonary artery. Compare that to this case of transposition of the great arteries where the two vessels run in parallel, both arising from the heart in parallel — Aorta from the right ventricle, pulmonary artery from the left.
A third way in which to assess the presence of transposition of the great arteries is to identify the nature of the great vessel arising from the left ventricle. The vessel that arises from the left ventricle should not bifurcate or split. Here we have an image of the heart with apex on top and the vessel arising from the left ventricle bifurcates, into an inverted Y. This is the pulmonary artery arising from the left ventricle designating the presence of transposition of the great arteries.
Transposition of the Great Arteries
Related Centers and Programs:
Cardiac Center, Fetal Heart Program