Segmental classification of Congenital Heart Disease
Segmental classification is a systematic approach to description of CHD and utilizes a three-letter designation. The first letter refers to visceroatrial situs. A normal situs solitus (S) includes the right atrium on the right and the left atrium on the left, as opposed to situs inversus (I). The second letter refers to the cardiac loop. A normal (D) loop indicates the right ventricle is on the right, while an abnormal (L) loop indicates that the right ventricle is on the left. The third letter refers to ventriculoatrial situs. In normal (S) situs, the aorta has rotated 150 degrees counterclockwise during cardiac development to connect with the left ventricle, while the pulmonary artery connects with the right ventricle. Abnormalities of this rotation can lead to transposition of the great vessels (TGV) or malposition of the great vessels (MGV). A normal segmental notation would therefore be (S, D, S).