A procedure is most often performed to treat Hypoplastic Left Heart Syndrome, certain types of mitral atresia, or other conditionsthat result in single ventricle circulation.
In these conditions, the most urgent problem is that the heart is unable to pump blood to the systemic circulation (i.e. to the body). The goal of the Norwood procedure is to connect the single ventricle to the systemic circulation.
Blood flow to the lungs is disrupted, and therefore an alternative path must be created to supply the lungs.