MAZE Procedure�is performed by Cardiothoracic surgeons on the left and right atrium for the treatment of atrial fibrillation. Atrial fibrillation is an abnormality of the electrical system of the heart. Normally, the heartbeat is triggered by an electrical impulse which starts in the Sinoatrial (SA) node.
This structure resides in the right atrium and is the normal "pacemaker" of the heart. The electrical signal to contract starts in the SA node and normally moves evenly across the atrium, triggering it to contract all at once. The impulse then travels across the atrio-ventricular (AV) node and triggers the ventricles (the main pumping chambers of the heart) to contract. This is called sinus rhythm. Atrial fibrillation occurs when this electrical impulse no longer travels from SA node to the AV node in the normal manner. Instead of the impulse traveling evenly across the atrium straight from the SA node to the AV node, the impulse is "side-tracked" such that the atrium is no longer triggered evenly and in synchrony, but is triggered one small region at a time. The atrium no longer contracts in a coordinated manner, but instead it fibrillates irregularly. The electrical signal to ventricle through the AV node is therefore irregular and hence the heartbeat is irregular.
The MAZE procedure is an "open heart" procedure requiring cardiopulmonary bypass (the heart-lung machine).The surgical procedure consists of creating a number of incisions in the atrium that disrupt the re-entrant circuits. Once the incisions are made, they are sewn together again. The atrium can then hold blood on its way to the ventricle and can squeeze or contract to push the blood in to the ventricle, but the electrical impulse cannot cross the incisions. The result is what looks like a children's maze in which there is only one path that the electrical impulse can take from the SA node to the AV node. The atrium can no longer fibrillate, and sinus rhythm (the normal rhythm of the heart) is restored.
