Approach
The Fontan is usually done as a two staged repair.
The first stage, also called a Bidirectional Glenn procedure or Hemi-Fontan (see also Kawashima procedure), involves redirecting oxygen-poor blood from the top of the body to the lungs. That is, the pulmonary arteries are disconnected from their existing blood supply (e.g. a shunt created during a Norwood procedure, a patent ductus arteriosus, etc.). The superior vena cava (SVC), which carries blood returning from the upper body, is disconnected from the heart and instead redirected into the pulmonary arteries. The inferior vena cava (IVC), which carries blood returning from the lower body, continues to connect to the heart.
At this point, patients are no longer in that delicate balance, and the single ventricle is doing much less work. They usually can grow adequately, and are less fragile. However, they still have marked hypoxia (because of the IVC blood that is not fed into the lungs to be oxygenated). Therefore most patients are referred for another surgery.
The second stage, also called Fontan completion, involves redirecting the blood from the IVC (inferior vena cava) to the lungs as well. At this point, the oxygen-poor blood from upper and lower body flows through the lungs without being pumped (driven only by the pressure that builds up in the veins). This corrects the hypoxia, and leaves the single ventricle responsible only for supplying blood to the body.
Read more about this topic: Fontan Procedure
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