Figure 1.

Schematic illustration of L-R asymmetry of human visceral organs. Normal L-R asymmetry (situs solitus) and three laterality defects that affect the lung, heart, liver, stomach, and spleen are shown. Heterotaxy with right isomerism is usually associated with a bilateral trilobed lung, a large symmetric liver, and the absence of a spleen. Heterotaxy with left isomerism often manifests as a bilateral bilobed lung, multiple spleens, and a pulmonary vein that drains into both the right and left atria.