What Is a Maze Heart Procedure?

Surgical technique is effective in treating atrial fibrillation

Atriall fibrillation


A maze procedure is a type of surgery used to control atrial fibrillation, a condition in which the heart rhythm is rapid and irregular. If atrial fibrillation cannot be controlled by medications or other treatments, a maze procedure may be considered.

Also known as the Cox maze procedure, the operation involves a series of incisions arranged in a maze-like pattern in the upper chamber of the heart, called the atrium. The resulting scar tissue helps channel the chaotic electrical impulses from the upper chambers to the lower chambers, called the ventricles. Doing so can help correct the scattered electrical impulses and restore normal heart rhythms.

The maze procedure has been supplanted in recent years by cardiac ablation procedures and is almost never performed as a stand-alone procedure. It is commonly used as an add-on procedure in people with atrial fibrillation who are having open heart surgery for some other reason, such as heart bypass surgery (CABG).


The maze procedure is used to correct atrial fibrillation (AFib) when anti-arrhythmia drugs or less invasive cardiac procedures fail to provide sustained relief. This includes cardioversion, a medical procedure in which mild electrical shocks are sent to the heart via electrodes on the chest.

Although it is used less commonly compared to minimally invasive cardiac ablation procedures, the maze technique offers higher cure rates and may be appropriate if other heart surgeries, such as a coronary artery bypass or mitral valve repair, are needed.

Beyond the alleviation of AFib symptoms, the maze procedure can help prevent long-term complications. Research suggests that uncontrolled AFib is associated with no less than a five-fold increased risk of stroke and a three-fold increased risk of heart failure.

Treatment Goals

To comprehend the goals of the maze procedure, you first need to understand how the heart works. In a normal-functioning heart, the heart's electrical system triggers the upper chambers of the heart (the left and right atriums) to contract, followed by the lower chambers of the heart (the left and right ventricles). The alternating contractions are timed perfectly so that blood is pumped in and out of the heart and delivered to the rest of the body in ample quantities.

The electrical impulse starts in a part of the right atrium called the sinoatrial (SA) node which acts as the heart's "pacemaker." When AFib occurs, these systems go awry. Instead of the SA node directing the electrical rhythm, multiple impulses fire rapidly fire at once, causing fast, chaotic rhythms in the atrium. This, in turn, causes the ventricles to contract irregularly, leading to a rapid and irregular heartbeat.

The maze procedure is used to stop these chaotic impulses and restore the normal rhythms of the upper and lower chambers of the heart.

Risks and Contraindications

The Cox maze procedure was traditionally performed as an open surgery and is still used as an add-on procedure during some open-heart surgeries. In such instances, the risks of the maze procedure are the same as for any other open-heart procedure. These include:

  • Chest wound infection
  • Breathing difficulties
  • Neuralgic chest pain
  • Arrhythmia (irregular heartbeats)
  • Blood loss
  • Blood clots
  • Edema (fluid overload)
  • Memory problems
  • Pneumonia
  • Respiratory failure
  • Kidney failure
  • Heart attack
  • Stroke

A newer technique, referred to as the Cox maze IV procedure, replaces traditional "cut-and-sew" surgery with devices that generate scar tissue using either cold (cryoablation) or electricity (bipolar radiofrequency). The Cox maze IV can access the heart either through the sternum (breastbone) or via a procedure known as a mini-thoracotomy in which a tiny incision is made between the ribs.

Because mini-thoracotomy is less invasive, the risks are correspondingly reduced and may include:

  • Chest wound infection
  • Neurologic chest pain
  • Arrhythmia
  • Blood loss
  • Accidental perforation of the esophagus or lung

When appropriate, the Cox maze IV performed through a mini-thoracotomy can be just effective as open-heart surgery with shorter recovery time.


Certain conditions contraindicate its use of the maze procedure. These include a previous right thoracotomy, poor left ventricle ejection fraction (a sign of heart failure), and severe atherosclerosis ("hardening") of the aorta, iliac, or femoral blood vessels.

Before the Procedure

If the maze procedure is recommended, it is likely because you have another heart condition that requires treatment in addition to AFib. The procedure is only recommended if you have symptomatic AFib. While it is less commonly used as a standalone procedure, it may be considered if you failed cardiac ablation or simply prefer a surgical approach.

Before the procedure, the cardiologist will want to assess if you are a reasonable candidate for treatment. If you are and can benefit from the procedure, you will be sent for a pre-surgery evaluation involving a series of tests, some of which may include:

Based on the results of the tests, you and your surgeon can decide if it is appropriate to move forward with the surgery.


The maze procedure is performed on an inpatient basis. The amount of time you need to spend in the hospital depends on whether you undergo open surgery or a mini-thoracotomy.

Even though the surgery will take between 2 and 4 hours, you may need to spend up to 10 days in the hospital, including a day or two in the cardiac intensive care unit (ICU).


The Cox maze procedure is performed in the cardiac surgical unit of a hospital.

What to Wear

You can wear whatever you like when you arrive at the hospital but will be asked to change into a hospital gown once you are in your room.

Avoid bringing jewelry and other valuables with you. Although some hospitals offer locked cabinets or bedside tables, they are usually small. Moreover, hospital admission forms will typically state that any lost or stolen property is not the responsibility of the hospital or any of its staff.

Food and Drink

The maze procedure needs to be performed while your stomach is empty. Typically, you will be asked to fast for 8 to 12 hours before your admission. Most maze procedures are performed in the morning. Your surgeon will give you exact instructions on what you can and cannot eat prior to the operation.

You will also be asked to stop taking blood-thinning medications such as Coumadin (warfarin) or nonsteroidal anti-inflammatory drugs such as Advil (ibuprofen) prior to the procedure. To avoid interactions and surgical complications, advise your surgeon about any drugs you are taking, whether they are prescription, over-the-counter, or recreational.

Cost and Insurance

The maze procedure is rarely an elective procedure and, as such, should be covered in part or in full by your health insurance. The cost of the procedure can vary enormously but can easily run into the tens of thousands for dollars, not including the cost of hospitalization and post-surgical care.

One way to manage costs is to buy a policy with a lower out-of-pocket maximum. What this means is that all your approved medical costs will be fully covered once you have paid the allotted annual dollar amount. As long your monthly premiums are manageable, the strategy can provide you a clear picture of the most you will have to spend for the operation.

In addition, you can negotiate an extended payment plan with the hospital or a discounted upfront cash payment with your specialists. Speak with a hospital financial advisor about strategies and discounts that may make the cost of surgery less burdensome.

What to Bring

You will need to bring some form of ID and your insurance card with you for hospital admissions.

Because you are likely to be in the hospital for several days, be sure to pack all of the clothing, medications, and self-care necessities to get through your visit comfortably and safely. But don't overpack since you will likely spend a day or two in ICU. It is often better to pack one small bag to carry with you and a second larger bag that a friend can bring once you've been transferred from ICU to a room.

You will also need to arrange for someone to drive you home after your discharge.

During the Procedure

A cardiothoracic surgeon will oversee the maze procedure rather than a general surgeon. Other members of the surgical team include the anesthesiologist and operating room nurses and technicians.

Because the maze procedure is generally performed alongside another heart surgery, there may be a perfusionist on hand to operate a heart-lung bypass machine if needed.


After you fill in the hospital registration forms, you will be accompanied to your room and provided a hospital gown to change into.

You will then meet with a nurse or technician who will confirm that you have not eaten after midnight. They will then perform a series of preoperative tests (including blood tests, blood oxygen, and blood pressure) and place electrodes on your chest to monitor your heart rhythm on an ECG machine. An intravenous (IV) line will be placed in a vein, usually in the back of your hand or in your arm.

The anesthesiologist will then meet to discuss any allergies or previous complications you may have had with anesthesia. When the workup is complete and you've been assessed to be ready for surgery, you will be wheeled into the operating room on a gurney and provided general anesthesia to put you completely to sleep.

Throughout the Procedure

Once the anesthesia takes effect, you will be intubated (in which a tube is inserted into the throat and a large airway of the lung) and connected to a ventilator to assist with breathing.

Since most maze procedures are performed as open surgeries, the operation would begin with a sternotomy in which an incision is made in the middle of the chest and the sternum (breastbone) is cut in two using a special saw, splitting the bone vertically. This allows the surgeon to have direct access to the heart.

You will then be hooked up to a heart-lung bypass machine which takes over the function of the heart and allows the surgeon to operate on a still heart. Using the Cox IV maze technique, the surgeon will access the right atrium and create a pattern of lines⁠—using either cryoablation or bipolar radiofrequency⁠—to block erratic electrical impulses and keep them moving through the heart.

Once the surgeon determines that all of the pathways have been scarred, the sternum will be closed using sterile surgical wire and the incision sutured. In some cases, chest tubes may be inserted in the chest to remove any blood that may accumulate around the heart.


After the maze procedure is complete, you will be transferred to a transitional room and then ICU where you will be monitored as you awaken from anesthesia. No medication is given to wake you. Instead, the anesthesia is allowed to fully wear off over several hours.

After the Procedure

You can expect to spend one or more days in ICU under the care of critical care nurses and an intensivist (ICU doctor). During the recovery, the heart’s electrical activity will be closely monitored to determine if the procedure was successful.

Once the anesthesia wears off and the breathing tube is removed, you will be helped to a chair within 12 hours of the surgery. This is a vital part of postoperative care as it helps prevent complications like blood clots and pneumonia.

There may also be temporary wires extending from the incision that can be connected to an external pacemaker in case of an emergency. (The surgeon may also recommend the placement of a permanent pacemaker during the surgery to provide better control of your heart rhythm).

After 1 to 2 days in ICU, you will be transferred to a regular nursing unit. Thereafter, you can expect to spend anywhere from 3 to 7 additional days in hospital depending on the complexity of the surgery and your response to postoperative care.

Cardiac rehabilitation will start while you are in hospital and continue once you are returned home.


The Cox maze procedure is a highly successful treatment for atrial fibrillation with response rates exceeding 90%. With that said, recovery from open-heart surgery can take 6 to 8 weeks and require intensive postoperative rehabilitation.

Roughly 60% of patients will experience skipped heartbeats or transient AFib in the weeks or months following the surgery due to swelling and inflammation of heart tissue. If these symptoms do not resolve on their own, a pacemaker may be recommended.

You will likely be placed on blood thinners and anti-arrhythmia drugs for a few months after the operation. Diuretics ("water pills") like Lasix (furosemide) may be prescribed to prevent fluid overload and reduce the risk of postoperative heart failure.


Once you are safely returned home, you will be asked to schedule a follow-up appointment with your surgeon within a week and then another with your cardiologist within a month. An ECG would be standardly ordered at 3 months, 6 months, and 12 months, and then once yearly thereafter.

A Word From Verywell

A maze procedure can seem very scary, particularly since it usually accompanies major heart surgery. However, if atrial fibrillation is undermining your quality of life, you can take solace in the fact that it is usually extremely effective.

If atrial fibrillation occurs on its own, you may benefit from an adjustment of your current medications or a less invasive procedure, such as cardiac ablation. Speak with your cardiologist about the most appropriate option and don't hesitate to seek a second opinion if you remain uncertain.

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Article Sources

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