What are the different Fontan procedures performed?
This is the way the operation was performed initially. In this operation, the collecting chamber of the heart taking the blue blood without oxygen coming from the body (the right atrium) was isolated from the rest of the heart. An expansion of this cavity (the right atrial appendage) was then connected to the right pulmonary artery. Some would call this operation a "classical" Fontan, because it was the one that was originally described by Dr Fontan.
A. The Atrio-Pulmonary connection (AP Fontan)
After many years, it was observed that the right atrium of some of the children who had a Fontan operation was progressively dilating. This dilatation seems to be occurring because of the turbulences of the blood as it was arriving from the veins coming from the body into this collecting chamber. This dilatation was annoying, because it was responsible for the formation of clots in the heart, and some of these patients had fast heart rates that made them sick.
A new design of the operation was then performed. In this operation, the vein draining the blood from the upper part of the body (the superior vena cava) was attached to the upper part of the right lung artery and the collecting chamber was attached to the underside of this same right lung artery. A half tube of artificial material was then sutured inside the collecting chamber to direct the blood coming from the lower part of the body in what looked much more like the inside of a cylinder inside the heart. This operation was designed so that this tube inside the heart would still have some potential for growth. This operation is called "lateral tunnel" or also "total cavo-pulmonary connection (TCPC)"
In this operation the superior vena cava is also, like in the Lateral Tunnel operation, connected to the right lung artery, but the vein coming from the lower part of the body (the inferior vena cava) is connected to an artificial (e.g. gore-tex) tube. The other end of this tube is then connected to the underside of the right lung artery. This operation was designed to try to have the best possible flow from the veins into the lung.
A fenestration is a communication between the channel carrying the blue blood to the lungs and the heart. It allows the passage of blood from the veins to the heart when the lungs are not functioning well. If the lungs are swollen such as during pneumonia, or soon after surgery, the blood will not flow passively very well through them, and there may not be enough blood going back to the heart. The heart could then not pump enough blood to the body and the patient may feel sicker than if they were just limited by their sick lungs. This fenestration is like a pop-up valve acting as a safety mechanism. It is known to be particularly useful soon after surgery.
It is not yet known whether it is good or not to keep this fenestration open for a long time or not. Some believe that it improves the exercise capacity, and that because on peak exercise, some more blue blood will go to the heart, and the heart will then be able to pump more blood through the body. Others think that the heart will not function as well if the blood that the heart ejects is more blue (with less oxygen), and believe that the people will be able to exercise better with the fenestration closed. We hope that future research will be able to show whether Fontan patients would be better with, or without, fenestration late after surgery.
Fenestration or no fenestration?
There are 3 different variations for the Fontan procedure that has evolved over time. Also see the Video from Dr Kirsten Finucane below (or click here) explaining how the Fontan procedure fixes the 'plumbing'
B. The Lateral Tunnel connection (LT Fontan)
C. The Extra-Cardiac Conduit connection (ECC Fontan)
Reprint of figures authorised by the Circulation Journal
(Circulation. 2007;116(suppl 1):1-157-1-164) Images: Fig A, B, C