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In the latest version of the procedure (Maze III), the "cut and sew" incisions created throughout the right and left atria are replaced with linear ablation lesions created with either radifrequency energy or cryothermy using a nitrous oxide cooled probe that is applied to the atrial tissue. Excellent results have been reported with the Maze III procedure with reported cure rates of over 90%. Despite these excellent clinical results, however, the Maze procedure has several major limitations which include:

• Major open-heart surgery which requires the patient to be placed on cardiopulmonary bypass (heart-lung machine).

• Technically difficult surgery which limits its widespread clinical application.

• Limited to patients with atrial fibrillation who required cardiac surgery for another serious heart condition (e.g., coronary artery disease; mitral valve replacement). For these patients, the Maze procedure was performed concomitantly with the other cardiac surgerical procedure.

• Not an option for younger patients with "lone" atrial fibrillation (atrial fibrillation that occurs in the absence of structural heart disease).

Complications of the Maze procedure are similar to those reported for other types of open-heart surgery and may include:

• Bleeding
• Infection
• Stroke
• Heart attack

The Maze procedure continues to undergo refinements in an effort to simplify and improve the surgical technique originally developed by Dr. James L. Cox and his colleagues back in the late 1980s. Recently, surgeons have developed a modification of the Maze procedure known as a "Mini-Maze". Advantages of the "Mini-Maze" technique include:

• May be performed using a minimally-invasive approach through a small thoracotomy incision instead of splitting the breastbone (sternum) as was necessary for previous versions of the Maze procedure.

• Requires a shorter duration of cardiopulmonary bypass (heart-lung machine) compared to the standard Maze procedure.

• Less need for insertion of a pacemaker as compared to the standard Maze procedure.

• Reduced blood loss, faster recovery, and less time spent in the hospital as compared to the standard Maze procedure.

More recent advances in the field of surgical ablation for atrial fibrillation using minimally-invasive "keyhole" techniques and thoracoscopic approaches have extended the utility of surgical ablation for atrial fibrillation beyond only those patients who required concomitant surgery for other heart problems such as coronary artery disease or valvular heart disease. Surgical ablation for atrial fibrillation is now being used even for younger patients with "lone" atrial fibrillation who do not have any underlying structural cardiac problems using these newer minimally-invasive or thoracoscopic surgical approaches that do not require any cardiopumonary bypass. The basic objective of these newer surgical ablation techniques still remains the elimination of the irregular electrical impulses that serve as the triggers for atrial fibrillation. In patients with paroxysmal atrial fibrillation these triggers originate in the pulmonary veins while in those with persistent or permanent atrial fibrillation the trigger for the abnormal impulses is the left atrium. These newer surgical ablation techniques, therefore, usually target these structures by pulmonary vein isolation and excision or exclusion of the left atrial appendage. Most commonly, radiofrequency energy or cryothermy (a nitrous oxide cooled probe) is used for surgical ablation of atrial fibrillation, however, alternative energy sources such as microwave, ultrasound, or laser may also be used. Early experience with the newer approaches for the surgical ablation of atrial fibrillation are encouraging and demonstrate a success rate of about 85% for the cure of paroxysmal atrial fibrillation after a 6-month follow-up period.

Pacemaker Therapy