Open Heart Surgery for Atrial Fibrillation: The Maze Procedure Explained

By Leslie Barlow

Atrial Fibrillation is the condition where the electrical signal which causes the upper chambers of the heart (the atria or atrium if singular) to contract, is bypassing them and they forget to beat on time. In many instances, surgery is not required as the condition may be mild so the patient does not know they have a condition or it simply does not affect their lives; in many other instances, the condition is controlled by medications or by using catheters rather than full-scale surgery. Where the condition is affecting the patient so they are suffering a loss of quality of life or where their prior history and risk factors mitigate towards surgical intervention, then an operation known as the Maze Procedure is performed to cure the condition.

To understand why the Maze Procedure works, we must first understand what is happening with your heart when you have atrial fibrillation. A heart is composed of two sets of paired chambers, the larger pair of chambers are the atria and they sit on top of the smaller, lower pair known as ventricles. The atrium's job is to collect blood from the veins and when it contracts, it forces the collected blood into the smaller ventricle chamber - the ventricle then contracts and this forces the blood back into and around the body. This double-beat is the signature of a healthy heart and is known as the Sinus Rhythm; but the process has to be carefully coordinated or the atrium may try to force blood into the ventricle when it is not ready to receive it - the atrium can quite literally, miss the beat.

The ventricle contract at a set rate, they don't need an electrical signal to tell them to contract but the atrium does need a pacemaker to tell it when to send the blood into the ventricle. This signal is created in the Sinoatrial Node (or SA Node for short) and it travels across the atrium causing it to contract and then terminates at the Atrioventricular Node (or AV Node for short). Atrial fibrillation is caused when the electrical signal takes a shortcut, missing out the atrium and going straight to the AV Node - the atrium does not contract properly, it flutters and if it beats properly it may simply be out of synchronization with the ventricles.

Where the Maze Procedure is recommended to cure the condition then the surgeon will make a series of incisions around the heart and then sew them back up again. This gives the appearance of a garden maze which is how the operation gets its name - The Maze Procedure. After the incisions are sewn up again, the atrium is able to hold blood and contract but the electrical signal cannot pass across the barriers created by the incisions - the signals must now follow the path around the incisions to get to across the heart and this directs them across the atria which now contract on cue.

The Maze Procedure is 80% to 100% successful in dealing with atrial fibrillation though patients may need to have an artificial pacemaker fitted where the disease has damaged the SA Node which generates the electrical signal to begin with. - 30540

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