The principle behind the maze procedure is based on an old observation: if one makes the volume of contiguous atrial muscles sufficiently small, a flicker cannot occur. The operation was developed in the 1980s by the American heart surgeon James Cox. He developed the operation through various intermediate stages. That is why the completed operation is called Cox ‘Maze-III operation.
The dotted lines illustrate where your physician first cuts the flesh of the heart. And then sews it back together. This creates a “maze” from the sinus node (which starts the normal heart pulses) to the AV node (which directs the impulses from the atria to the heart chambers).
The operation is technically difficult, and is only to a limited extent admitted in various cardiac centers. In practiced hands, however, it is an effective treatment of atrial fibrillation with a relatively modest risk for complications. In around 90% of cases it is possible to restore a normal heart rhythm (sinus rhythm) during the operation. Some, however, subsequently get atrial flutter, which can then be treated with a catheter ablation. Approximately 10% must subsequently have a pacemaker – most often due to the influence of the sinus node. The Maze-III operation is a serious heart operation, where you have to expect a significant recovery period afterwards – often up to half a year.
There is a further development of the operation, which is called Maze-IV, where you use cold (Cryo-ablation), instead of a knife, to make the lines in the maze. The advantage of this technique is that it can be made using keyhole surgery. The results at Maze-IV are not as well substantiated as at Maze-III.
One of the benefits of Maze surgery is that you simultaneously remove the atrial auricle from the left atrium. This reduces the risk of blood clots in the future.
Due to the technical difficulty of performing a Maze-III operation, various alternatives have been developed, which are collectively called mini-Maze treatments. These approaches are typically “just” a surgical based isolation of the tissues in the left atrium around the mouth of the blood vessels from the lungs. In fact, the same thing is done with a catheter-based ablation. Thus, no maze is formed from sinus node to AV node – which is why the term mini-Maze is misleading. The results of this type of surgery are comparable to the results of catheter ablation – not better.
When are the Maze operations used?
Both Maze-III and the so-called mini-Maze procedures are most often used if other heart surgery is already required. For example, repairing or replacing a heart valve in a patient who also has atrial fibrillation. Occasionally, one can also opt for surgical treatment for atrial fibrillation without the simultaneous need for other heart surgery. This will typically happen if repeated catheter ablations have not yielded sufficiently good results.