The palliative Norwood procedure is used for children with only one pumping chamber in their heart, for example in aortic atresia or hypoplastic left heart syndrome.
The Norwood is usually done as part of a series of surgeries. It involves reconstructing the aorta using the pulmonary artery, to allow the ventricle to easily pump blood out to the body. It also involves placing a Blalock-Thomas-Taussig shunt (BTT shunt) to maintain blood flow to the lungs.
The risks involved with the Norwood procedure are high. This is a major and complex operation requiring expert care before, during, and after the operation. The teamwork among cardiology, cardiac surgery, anaesthesia, critical care, and all other supporting staff is crucial. Mortality can be as high as 20% even at the best centres, and the potential for complications is elevated with a prolonged hospital stay.
After the initial Norwood operation, the heart is fragile and the flow of oxygen to the lungs is completely dependent on the BTT shunt. The risks associated with the BTT shunt include the potential for clots to develop in the shunt and these children are maintained on blood thinner medications to try and prevent this complication.
The complete palliation involves two other procedures: the cavopulmonary anastomosis (Glenn procedure), or second stage, and the Fontan, or third stage. The long-term outcome of these combined procedures is not well known, since the oldest surviving individuals are only in their 30s.