Atrial Switch Operations

Now that you have read about the Arterial Switch Operation (ASO), let us now see what the other operations for TGA are.

How is an atrial switch operation done ?

There are two types of atrial switch operations - the MUSTARD operation, and the SENNING operation. Both are similar in principle, but differ in technique.
The atrial switch operation is an open heart procedure and is carried out with the assistance of a heart-lung machine. The right atrium is opened, and the wall between the atria is fully removed. Using pericardium (Mustard) or flaps created from the atrial septum and wall (Senning), a "baffle" is constructed directing blood from the veins in the right atrium towards the left ventricle. The same baffle also directs blood from pulmonary veins to the right ventricle. The circulation is therefore restored to normal in a functional sense.

When should an atrial switch operation be preferred ?

The atrial switch was the first to be developed for TGA and was frequently performed in the 1970's and early 80's. It has many drawbacks, and so today, the ARTERIAL switch is the operation of choice for TGA. Still, Mustard and Senning operations are not obsolete.
Some patients are not suited for an arterial switch procedure. This may be due to severe abnormalities of their coronary arteries, which make it very difficult for the surgeon to re-implant them at operation. If the patient comes to medical attention at a later age - beyond 1 to 2 months - an arterial switch is not possible. Some institutions may not have adequate experience with arterial switch, which is a difficult operation to learn. In any of these situations, an atrial switch procedure - Mustard or Senning - may be preferred.

What are the problems with an ATRIAL switch procedure ?

While risks of operation are similar to ASO, the long term outcome is slightly inferior to it. Rhythm disturbances - Arrhythmias - are very frequent and occur in almost one-half of all survivors. Exercise capacity is less than normal. Delayed failure of the right ventricle may occur. This is unusual with simple TGA, but is more common in patients with a coexisting VSD. Another major drawback of the atrial switch is the chance of obstruction of the superior vena cava (SVC) - the vein which returns impure blood from the head and arms back to the heart. The SVC may become blocked by the "baffle" inside the atrium and produce problems needing re-operation.

Some Special Circumstances

 

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