Internal cardiac crux: two-dimensional echocardiography of normal and congenitally abnormal hearts.

The internal cardiac crux is an important anatomic landmark for the appreciation of both normal and congenitally altered anatomy. The four-chamber two-dimensional echocardiographic plane of section at the internal crux is the most feasible tomographic plane. The unique noninvasive access to the internal crux anatomy is frequently more sensitive and diagnostic than other imaging modalities, including angiography. This report describes the echocardiographic and anatomic landmarks of the normal crux and the more frequent congenital anomalies that alter these relationships.