The most common of these procedures are the microwave minimaze and the Wolf minimaze, the latter pioneered by Dr. Randall Wolf from the University of Cincinnati Center for Surgical Innovation. He has used the term "Wolf MiniMaze" to help distinguish it from other minimally invasive procedures for cure of AF.
During the Wolf minimaze, the surgeon places clamp-like tool on the left atrium near the pulmonary veins, and ablation is performed by heating the atrial tissue between the jaws of the clamp, cauterizing the area, much like a catheter ablation. The nerves that cause AF are in the area and are eliminated as well. In many institutions, the surgeon and the electrophysiologist work closely together to ensure that the ablation is complete, and that the overactive nerves are no longer a problem. In addition, the Ligament of Marshall is removed. It is a vestige of a vein that was required during fetal development, but is no longer needed. In fact, it has been found to be one of the areas that can cause AF in patients who otherwise have a normal heart. Finally, the part of the left atrium (the “appendage”) in which most clots form is removed, which may reduce the long-term likelihood of stroke even if AF were to return.
The Wolf MiniMaze is sometimes described as "Limited Thoracotomy Bipolar Epicardial RF Ablation with Removal of the Ligament of Marshall and the Left Atrial Appendage". That sounds complex, but when discussing procedures, it's very important to be precise, because the common names used for these procedures are so similar even though the procedures themselves are very different. Indeed, the term "Maze" has been used to describe everything from a catheter ablation, which is not surgery at all, to a full, open-chest Cox-Maze III. A thorough history of the use of the minimaze terms can be found on the Minimaze Procedures page.
The Wolf MiniMaze is easily confused with the Completely Endoscopic Microwave Treatment of Atrial Fibrillation, which has sometimes been referred to as the "microwave minimaze", but these two procedures are not similar. The microwave procedure is even less invasive, using smaller incisions.
How successful is it?
Dr. Wolf published his results in his first 29 patients (Wolf 2005); his follow-up is relatively short (average, 6 months), and two patients were lost to followup, but 21 of the 23 patients in whom more than three months of follow-up was available were found to be free of AF. An additional 6 patients continued on antiarrhythmic medications; hence 15 of 23 (65%) were free of both AF and medications three months after surgery. There were no deaths or strokes; one patient became anemic and required transfusion after discharge from the hospital.
Since that time several other investigators have published their results; a comparison of the results of various minimaze procedures is available on the Outcomes page