The Fontan procedure represents a variety of techniques used for an entire classification of heart defects. The Fontan procedure is used for children who were born with only one functioning ventricle.
Ordinarily, the heart has two main pumping chambers (ventricles). One ventricle pumps blood to the lungs and one pumps blood to the body. Children with only one ventricle have that ventricle pumping blood to both the body and the lungs at the same time. Ideally, all of the blood which is pumped to the body is full of oxygen, and the blood which is pumped to the lungs needs to get oxygen. If one ventricle is used to pump blood to both places, the oxygenated and unoxygenated blood is mixed, which is inefficient.
Approximately 30 years ago, surgeons determined that you did not always need the force of a ventricle to get blood through the lungs. It would be possible to directly connect the large veins (which return unoxygenated blood from the body) to the pulmonary artery (which delivers blood to the lungs). The pressure which exists in these veins is enough to push blood flow through the lungs. The blood is then returned to the heart oxygenated, where the ventricle pumps it out to the body. In this way, the lungs receive only unoxygenated blood and the body receives only oxygenated blood. For a child with a single ventricle, this circulation pattern, known as the Fontan circulation, is the best pattern available.
The Fontan circulation is very sensitive to increased resistance to blood flow through the lungs. Since there is no ventricle pumping blood through the lungs, any narrowing or obstruction to blood flow in the lungs (such as a narrowing of the pulmonary artery) is very poorly tolerated. Children who have these problems often cannot have a Fontan procedure. Even for those children who successfully undergo a Fontan, the amount of pressure left in their large veins (the ones connected to the pulmonary artery) is higher than usual. Approximately 1% of Fontan patients per year will develop problems (usually intestinal) related to this.
The Fontan procedure can be performed using many different techniques. The child's particular type of single ventricle defect along with the preference of the surgeon dictates the Fontan technique. Surgery is performed with a vertical incision in the middle of the chest. The heart-lung machine is always used. A small hole (fenestration) is sometimes left between the pulmonary (lung) and systemic (body) circulations. This may cause the child to be slightly cyanotic (blue) after the operation, although not as blue as most were before the operation. The fenestration usually closes on its own or can be closed later without open surgery.
Children after Fontan surgery characteristically build up a lot of fluid in their chest cavity in the space between the lungs and the chest wall. This is drained with tubes left in at the time of surgery. It is common for children to spend 1-2 extra weeks in the hospital past the usual point of recovery waiting for this fluid accumulation to stop.
The Fontan procedure often represents the best approach for children with single ventricles, although it is not perfect. It is necessary to discuss a child's case carefully with a physician to understand the particular concerns for that child.
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