MAZE Ablation

Atrial fibrillation is an abnormal heart rhythm that affects millions of people in the USA. 

The atria are the 2 chambers of the heart that receive blood back from veins. 

The atrial walls have some muscle but are not highly muscular. The atria can contract slightly but not as vigorously as the ventricles. 

In a normal state, the atria and the ventricles contract in a coordinated way. 

There are special cells in the heart that can create electricity. 

These special cells are located in the Sinus Node. 

The electrical impulse created in the Node travels down a cellular pathway to another set of special cells called the AV node. 

The electrical impulse then travels down additional cellular pathways to the ventricular muscle. 

The electrical impulses can be recorded with an EKG. 

In certain disease states, the cellular pathways become blocked or impaired. In such cases, the electrical impulses cannot move along like usual. 

Depending on how the pathways are disrupted, atrial fibrillation can result. 

Fibrillation refers to shaking or twitching. Without coordination. 

There is a big difference between atrial fibrillation and ventricular fibrillation. Ventricular fibrillation involves uncoordinated twitching of the ventricles. Ventricular fibrillation (VT) is life-threatening, because the ventricles cannot effectively move blood to the body. VT often requires an external electrical shock to restore a normal rhythm.   

Atrial fibrillation is not life-threatening like VT. 

The main risk of afib is stroke. Because the atria are shaking randomly and are not contracting in a coordinated manner, the blood in the atria can stagnate, especially along the walls. 

If the blood stagnates, it can clot. And if a clot forms and then gets out of the heart, it can go to the brain and cause a stroke. 

If a-fib persists, most patients are put on a blood thinner, so that a clot does not form in the heart, thereby reducing the risk of stroke. 

Afib can be caused by many different things. Causes or contributing factors of afib include:

High blood pressure

Alcohol intake

Coronary Artery Disease

Obesity

Heart valve problems

COPD

Cigarette smoking

Diabetes

But up to half of patients who develop afib do not have a specific risk factor thought to account for the afib. 

With afib, some patients may experience a sense of their heart beating fast or racing, a finding known as palpitations. Some patients may feel short of breath or tired. 

Some patients do not experience symptoms and do not know when they are in afib. 

Afib is usually diagnosed with an EKG. Sometimes an erratic pulse may tip a physician off that a patient may be in afib. 

The first therapy for afib is usually medications. Certain medicines can help restore a normal heart rhythm. 

If medicines are not successful to restore a normal heart rhythm, sometimes an electrical impulse is used to "shock" the heart back into a regular rhythm. This is called cardioversion

If cardioversion is unsuccessful to restore a normal heart rhythm, an ablation can sometimes be done. An ablation is usually performed by an electrophysiologist, a cardiologist who is a specialist in heart rhythm problems. 

An ablation is usually performed using small catheters guided up from the groin into the heart. The catheters are used to damage the atrial tissue. 

Yes, you read that right - the idea is to damage the heart tissue! On purpose. This would never be a good idea on the ventricles - damaging the heart muscle would weaken it. 

But since the atria are not powerful and only channel the blood rather than pump it at high pressure, this form of damage does not impair the heart function. 

The damage that is done creates lines that are electrically insulating. The electrical impulses traveling along abnormal pathways must stop at these lines, which tends to extinguish the electrical impulses. At the same time, this encourages the electrical impulses to return to the normal pathways, thereby restoring a normal heart rhythm. 

The MAZE procedure is a form of ablation done with open surgery. 

Typically, a MAZE is performed when a heart operation is being done for another reason; that is, if a patient is getting a bypass operation and has afib, then a MAZE would be done along with the bypass. Or if a patient is getting a valve operation and has afib, then the MAZE is performed along with valve surgery.

OPERATION

The MAZE was originally developed by Dr. Cox in 1987. He cut lines in the atrial tissue and sewed the tissue back together. 

Now, technology can accomplish the same result. 

Dr. Pool uses a combination of radiofrequency and cryo technologies to accomplish his MAZE procedures. 

Radiofrequency ablation uses electricity to create heat that will result in scar tissue formation in the atrial tissue. This scar will not conduct electrical impulses, thereby helping to stop afib. 

The radiofrequency ablation device is shaped like a clamp. Dr. Pool calls it the "AFLAC" because it is shaped like a duck's bill. The clamp can be placed around certain atrial structures and the ablation line created. 

Cryoablation uses very cold temperature to create scar tissue. The cryo probe is more flexible than the RF probe and can get to certain places in the atria that the AFLAC cannot go. 

Performing the MAZE as part of a heart operation adds some time, usually about 20-30 minutes. This is time well spent if it means the patient does not have afib long-term. 

Most studies on the MAZE suggest that it does not add to the risk of a heart surgery. 

God bless & heal you! 

J. Mark Pool, MD

ABTS Board-certified

214-692-6135

Member of Society of Thoracic Surgeons