Purpose or Case Report: Congenital heart diseases often occurs secondary to a variety of insults and rotational errors during development in utero. These can range from a spectrum of simple to more complex pathologies including arterial switches. It is important for radiologists to recognize the embryology and complications of arterial switches to further management. Today largely secondary to new advances in technology both corrected and uncorrected arterial switches are diagnosed more commonly; previously many patients with arterial switches may not have survived into adulthood.

In utero, the primitive truncus is normally positioned anterior and midline. It eventually divides into the aorta and the pulmonary artery, which then rotates clockwise 150 degrees such that the pulmonary artery lies anterior to and left of the aorta. When variations occur it can result in a congenitally corrected transposition such as L- transposition of the great arteries (L-TGA) where the two ventricles are morphologically switched in position. With L-TGA, the truncus rotates 30-degrees clockwise which results in the aorta being anterior and leftward in relation to the pulmonary artery.

In uncorrected transposition (R-TGA) the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle, secondary to a 30-degree counterclockwise rotation of the primitive truncus, the aorta is then located rightward and anterior to the pulmonary artery. This condition needs to be corrected surgically due to cyanosis resulting from the right ventricle not being able to supply the systemic circulation. Other variations of arterial switches that can occur is situs inversus where the rotation of the aorta and pulmonary artery is completely opposite of that which would be considered normal. Lastly in truncus arteriosus, the primitive truncus does not divide into a separate aorta and pulmonary artery. We will provide several cases from our institution of arterial switches on imaging as well as diagramatic representative models describing the embryology of how arterial switches and rotations occur. We also discuss the repairs and complications of these cases.
Methods & Materials:
Results:
Conclusions: Congenital arterial switches and complications from repairs can be confusing but are becoming more commonplace. It is thus important for radiologists to understand the embryology and identify the imaging characteristics.