What is this procedure, and how does it differ from other approaches?
Clamp used for the Wolf minimaze
The Maze III procedure requires an incision in the sternum (breastbone), cardiopulmonary bypass, and making extensive incisions in both upper chambers. The minimaze procedures do none of these; instead, they use small incisions between the ribs, are performed on the normally beating heart and hence does not require cardiopulmonary bypass, and make few or no true incisions on the heart (one when removing the left atrial appendage). 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.
Bipolar RF clamp eliminates nerves and
conduction from pulmonary veins to atrium.
The Wolf MiniMaze is one of several surgical procedures intended to permanently cure AF. It is more accurately described as "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 About Minimaze.org 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" or "micromaze", but these two procedures are not similar. The microwave procedure is even less invasive, using smaller incisions. Among the important differences, perhaps the most important is that only during the Wolf MiniMaze is it possible to carefully evaluate that the causes of the AF itself (as they are currently understood) have been modified:
- conduction between the left atrium and the pulmonary veins, and
- activity of the autonomic nerves (ganglionated plexi, GPs).
Because demonstrating these usually requires an electrophysiologist during surgery, this testing is not performed in all institutions. That's unfortunate; the long-term freedom from AF may depend on proving conduction block and elimination of the GPs.
Video of the minimaze procedure;
requires Flash 7
Other aspects of the Wolf MiniMaze which may distinguish it from other types of minimaze procedures include:
- Removal of the Ligament of Marshal, which is known to be one of the causes of AF
- Removal of the Left Atrial Appendage, from which most strokes from AF originate
How successful is it?
Dr. Wolf recently published his results in his first 29 patients (ref); 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.
What is it like to have this surgery?
Institutions performing these procedures will differ somewhat in the details. Generally, you should expect to come to the hospital on the morning of your procedure, and be admitted to the Short Stay unit or the Cardiac Surgical floor. From there you would go to the operating room, where the anesthesiologist would put you asleep, and on a ventilator. Sometimes epidural anesthesia is also used. The cardiac surgeon performs the operation, and the electrophysiologist makes sure that conduction between the atrium and pulmonary veins is gone, and the nerves that can cause AF are eliminated.
A more complete description of the tests and office visits before and after your procedure can be found on the Before and After Surgery page.
The surgery requires a three inch incision between the ribs, with two smaller ones less than an inch long, on each side of your chest. The operation takes about 4 hours. A brief video of the minimaze procedure is available on this page; longer and more detailed ones may be viewed or downloaded on this page.
Right side, 3 months post-op
When your surgery is complete, you go to the Cardiac Surgical Floor. You would have tubes in the incisions in the chest to take care of any drainage for another day or so. There is some discomfort with the incisions, which may last several days or longer; you would likely stay in the hospital about four days.
Blood thinners are begun as soon as possible, usually the first day after your surgery. The heart rhythm medicines that you were on are usually continued for the first eight weeks following surgery. Anti-inflammatory steroids (prednisone) are given to prevent inflammation around the heart, where the surgery was performed (pericarditis), so you will go home on several medications, including prednisone, blood thinners, medicines to prevent AF, and other medicine that you may have required prior to surgery. The prednisone and antiarrhythmic medications are soon stopped, but blood thinners may continue to be required.
Some AF may persist for the next 6 weeks or so, while the healing process completes. The recovery period varies, but most people would not resume work for about two weeks. You will be followed in clinic by both surgical and electrophysiologic members of the team; for more specific information about this, read Before and After.