Maze Procedure

Atrial fibrillation is a disorder found in about 2 million Americans. The upper two chambers of the heart normally beat in a coordinated fashion causing the lower chambers of the heart to eject blood to the body in a regular rhythm. This is depicted by Figure A at left. Figure B represents atrial fibrillation where there is discoordinated electrical output from the upper chambers, causing irregular ejection of blood from the heart. The normal EKG is seen below. This corresponds to the electrical activity in Figure A above. Undernearth the normal EKG is one showing atrial fibrillation. This corresponds to the electrical activity seen in Figure B above.

With irregularly contracting upper heart chambers, blood can pool and clot. If a piece of blood clot breaks free from the heart, it may travel to the brain causing a stroke, to the limbs causing acute ischemia (lack of blood supply), or to other vital structures such as the kidney or bowel. Atrial fibrillation is treated with medications to slow the heart to a more normal rate, to make the heart rhythm regular, and to prevent blood clots from forming by anticoagulating or thinning the blood. In selected patients, especially those undergoing open heart surgery for reasons other than atrial fibrillation, an operation can be performed to eliminate the irregular rhythm of atrial fibrillation.

This operation is called the Maze procedure. A malleable metal probe (pictured at right) is connected to an argon gas source, which cools the metal probe to almost -160° Celsius. When placed on specific areas of the upper chambers of the heart, the freezing will interrupt abnormal electrical pathways. This prevents the occurance of atrial fibrillation. The effect of freezing may take several months to normalize the heart rhythm, and patients usually continue to take blood thinners and heart rhythm medications during this time. The procedure has been shown to be greater than 80% effective in terminating atrial fibrillation.

More recently, the maze procedure can be performed using very small incisions on either side of the chest. With the aid of video thoracoscopy, cure of intermittant atrial fibrillation exceeds 90% using newer radiofrequency devices.