In hypoplastic left heart syndrome and related single-ventricle conditions, the left ventricle and native aorta cannot adequately support systemic circulation.
Before intervention, systemic blood flow depends on the ductus arteriosus. As the ductus narrows or closes, systemic perfusion can deteriorate rapidly.
The Norwood procedure is the first stage of surgical palliation designed to create a more reliable pathway for systemic output.
The operation does not create two separate ventricles or two normal circulations. Instead, it reorganizes blood flow so that the single ventricle can support the body.
The Norwood reconstruction creates a neo-aorta so that the single ventricle can eject blood to the systemic circulation.
Pulmonary blood flow is provided through a separate pathway, such as:
After the Norwood, the single ventricle supports systemic output, while pulmonary blood flow depends on the surgically created pulmonary blood flow pathway.
Systemic venous and pulmonary venous blood continue to mix before leaving the ventricle.
Even though the anatomy has changed, the Norwood circulation remains parallel physiology.
Blood leaving the single ventricle must still be distributed between: