If the left ventricle is defective and the right ventricle is relatively healthy, the Norwood procedure turns the right ventricle into the main pumping chamber of the heart. This is accomplished by connecting the aorta and the pulmonary artery with a vein graft from elsewhere in the body or synthetic materials such as Dacron or Gore-Tex. This new pathway between the aorta and the pulmonary artery is called a Blalock-Taussig shunt.

One of the original shunts used for this procedure was known as a Blalock-Taussig shunt, which connected one of the arteries in the arm directly to pulmonary artery. This has been replaced with a modified Blalock-Taussig shunt, which uses synthetic material and avoids the need to reroute the blood supply to the arm. Newer modifications include the Sano shunt, which connects the right ventricle and pulmonary artery. Many centers have adopted this new approach because it appears to help patients remain stable immediately after the surgery.

A component of the stage I Norwood procedure is reconstructing the aorta by sewing the base of the pulmonary artery (main pulmonary artery) to the underdeveloped base of the aorta. Other segments of the aorta may require synthetic material to enlarge the vessel. The pulmonary arteries that go the lungs (right and left pulmonary arteries) are completely separated from their base and receive all of their blood flow from either the Blalock-Taussig shunt or the Sanno procedure.  The valve of the pulmonary artery will function as the aortic valve for the rest of the patient's life.

Under normal circumstances, the blood in the right ventricle is oxygen-poor blood returning from the body. However, in addition to creating a shunt during the first stage of the procedure, the physician may also cut away the septum between the heart’s two upper chambers (atria). This allows oxygen-rich blood returning from the lungs to the left atrium to mix with the oxygen-poor blood in the right atrium. In turn, this oxygen-rich blood passes into the right ventricle and is pumped out to both the lungs and the rest of the body via the pulmonary artery and the newly established shunt.

After the first stage of the procedure, the right ventricle becomes the main or only chamber responsible for pumping blood to the lungs and to the tissues and organs of the body.

A newer procedure, termed a hybrid Norwood procedure, has also been developed that avoids use of the heart-lung machine in patients with a left ventricle defect. During this less-invasive procedure, physicians open the chest briefly to gain access to the pulmonary arteries and aorta. They then place restrictive bands around the pulmonary arteries to narrow them and raise the blood pressure in the right side of the heart. Next, they connect the aorta to the right side of the heart with a stent. This creates a right-to-left shunt in which the high blood pressure in the right side of the heart forces blood through the stent and into the aorta. This procedure can replace the first stage of the three-stage process in some patients, allowing them to strengthen before the second and third stages are performed. This procedure is still being developed and is still not widely undertaken.