The microwave minimaze is notable as it was the first curative procedure for AF to be considered a “minimaze” procedure in the current sense of the term:
- no requirement for median sternotomy
- performed on the beating heart, without cardiopulmonary bypass
The microwave minimaze requires three 5 mm to 1cm incisions on each side of the chest for the surgical tools and the endoscope. The pericardium is entered, and two sterile rubber tubes are threaded behind the heart, in the transverse and oblique sinuses. These tubes are joined together, then used to guide the flexible microwave antenna energy source through the sinuses behind the heart, to position it for ablation. Energy is delivered and the atrial tissue heated and destroyed in a series of steps as the microwave antenna is withdrawn behind the heart. The lesions form a "box-like" pattern around all four pulmonary veins behind the heart. The left atrial appendage is usually removed. Dr. Saltman’s thorough presentation of this procedure can be reviewed here: http://www.ctsnet.org/sections/clinicalresources/adultcardiac/expert_tech-11.html
How successful is it?
As with any of the potentially curative procedures for AF, the most important determinants are patient characteristics rather than the procedure type. Some patients are more likely to have a good outcome based on the type of AF they have, left atrial size, and other factors.
For a period of time, the microwave minimaze was the most popular minimaze procedure. However, in 2007, one of the proponents of this procedure published results (Pruitt 2007) which showed it to be less effective than previously thought, and this procedure is chosen infrequently today.