The Norwood Procedure is a complex surgical method used primarily to treat hypoplastic left heart syndrome (HLHS) and other similar congenital heart defects where the left side of the heart is underdeveloped. It's typically performed within the first few weeks of a newborn's life as a life-saving intervention. The procedure is done in stages, commonly referred to as Norwood Stage I, II, and III, each aiming to improve the heart's ability to pump blood effectively despite the structural abnormalities.

Here's a brief overview of the stages:

1. Norwood Stage I: This initial surgery is the most critical and is usually performed shortly after birth. The goal is to reconstruct the aorta and connect it directly to the right ventricle, essentially using the right ventricle to pump blood to both the lungs and the rest of the body. A shunt is also placed to ensure that the lungs receive an adequate blood supply.

2. Norwood Stage II: Also known as the Glenn or Hemi-Fontan procedure, this stage is typically performed when the child is between 4 and 6 months old. It involves redirecting oxygen-poor blood directly to the lungs by connecting the superior vena cava (the large vein carrying deoxygenated blood from the upper half of the body) to the pulmonary arteries. This reduces the workload on the right ventricle by allowing blood to flow passively to the lungs without passing through the heart.

3. Norwood Stage III: Known as the Fontan procedure, this final stage usually occurs between 18 months and 4 years of age. It completes the separation of the oxygen-poor and oxygen-rich blood by directing the blood returning from the lower body directly to the lungs. This is achieved by connecting the inferior vena cava to the pulmonary artery, often with a conduit or tunnel.

The Norwood Procedure is a critical and complex series of surgeries that require a child to be closely monitored and may involve additional interventions to address complications or further refine the heart's function. It's a palliative procedure rather than a cure, aiming to improve the quality of life and extend the lifespan of children born with significant heart defects. With advances in surgical techniques and post-operative care, the outlook for children undergoing the Norwood Procedure has significantly improved over the years.