The heart is a complicated organ both in how it is composed and how it actually works; you can understand this given the job it has to do and how vital it is to our everyday lives – if something does not work properly, it frequently results in a huge loss of quality of life and is the cause of death for many, many people.



Picture two sets of two chambers stacked on top of each other – the larger, upper pair of chambers are known as the atria (singular is atrium) and their job is to gather in blood after it has passed through the lungs and which is full of oxygen to be distributed around the body. Once they are filled, they contract and this forces the blood into the smaller, lower pair of chambers which are called ventricles. The ventricles then contract and this forces the blood around the body under pressure – it is the twin set of contractions by the upper atria and followed by the lower ventricles which gives us the double-beat signature of a healthy heart and is known to doctors as the Sinus Rhythm.

This double-beat process must be coordinated so the atrium knows when to contract and force the blood into the smaller ventricle – if it misses the beat, less blood is pushed into the ventricle which may not be ready to receive the blood in the first place. The trigger for the atrium to contract is an electrical signal sent from what is known as the Sinoatrial Node (or SV Node). This signal travels across the atrium and terminates at the Atrioventricular Node (or AV Node) – note that the ventricles will contract no matter what the signal does, they don't need this particular impulse to contract.

Now imagine that the signal is somehow getting disrupted and the atrium is not contracting when it is supposed to – the atrium is trying to pump blood into the ventricle but the ventricle is not ready. This is known as atrial fibrillation and is caused by the electrical impulse taking a short cut which bypasses the atrium. While the condition may be so mild that the patient is unaware of it or can live quite happily without any intervention, other cases require medication or the use of catheters to regulate and control the situation. In serious cases, open heart surgery is required and the particular operation is the Maze Procedure.

The surgeon makes a series of incisions around the atrium which are then sewn back up – the result looks like a child's maze (hence the name). After the operation, the atrium is able to hold blood and contract normally but the electrical signal cannot cross the barriers created by the incisions – it must follow the path which has been created by the Maze Procedure. This stops the signal from bypassing the atrium and ensures a healthy sinus rhythm is established again but in some cases a pacemaker must be inserted because the SV Node has been damaged as a result of the disease.