Maze Procedure for Atrial Fibrillation

Definition
Purpose
Demographics
Description
Diagnosis/Preparation
Aftercare
Risks
Normal results
Morbidity and mortality rates
Alternatives

Definition

The Maze procedure, also known as the Cox-Maze procedure, is a surgical treatment for chronic atrial fibrillation or atrial flutter. The procedure restores the heart’s normal rhythm by surgically interrupting the conduction of abnormal impulses.

Purpose

When the heart beats too fast, blood no longer circulates effectively in the body. The Maze procedure is used to stop this abnormal beating so that the heart can begin its normal rhythm and pump more efficiently. The procedure is also intended to control heart rate and prevent blood clots and strokes.

Demographics

The Maze procedure has been performed since 1987 and was developed by Dr. James L. Cox. The average age of patients undergoing this procedure is about 52.

The Maze procedure is used to treat chronic or paroxysmal atrial fibrillation, a type of abnormal heart rhythm in which the upper chamber of the heart quivers instead of pumping in an organized way. In general, patients usually have atrial fibrillation for about eight years before undergoing the Maze procedure. The Maze procedure may be recommended for patients who need surgical treatment for coronary artery disease or valve disease. Therefore, the Maze procedure may be performed in combination with coronary artery bypass surgery (CABG), valve repair, valve replacement, or other cardiac surgery.

The Maze procedure may be recommended for patients whose atrial fibrillation has not been successfully treated with medications or other non-surgical interventional procedures. It may also be a treatment option for patients who have a history of stroke or cardiac thrombus.

Abnormal heart rhythms are slightly more common in men than in women, and the prevalence of abnormal heart rhythms, especially atrial fibrillation, increases with age. Atrial fibrillation is relatively uncommon in people under age 20.

Description

Elective Maze surgery is usually scheduled in advance. After arriving at the hospital, an intravenous (IV) catheter will be placed in the arm to deliver

KEY TERMS

Ablation— The removal or destruction of tissue.

Ablation therapy— A procedure used to treat arrhythmias, especially atrial fibrillation.

Ambulatory monitors— Small portable electrocardiograph machines that record the heart’s rhythm, and include the Holter monitor, loop recorder, and trans-telephonic transmitter.

Anti-arrhythmic— Medication used to treat abnormal heart rhythms.

Anticoagulant— A medication, also called a blood thinner, that prevents blood from clotting.

Atria— The right and left upper chambers of the heart.

Cardiac catheterization— An invasive procedure used to create x rays of the coronary arteries, heart chambers and valves.

Cardioversion— A procedure used to restore the heart’s normal rhythm by applying a controlled electric shock to the exterior of the chest.

Echocardiogram— An imaging procedure used to create a picture of the heart’s movement, valves and chambers.

Electrocardiogram (ECG, EKG)— A test that records the electrical activity of the heart using small electrode patches attached to the skin on the chest.

Electrophysiology study (EPS)— A test that evaluates the electrical activity within the heart.

Head-upright tilt table test— A test used to determine the cause of fainting spells.

Implantable cardioverter-defibrillator (ICD)— An electronic device that is surgically placed to constantly monitor the patient’s heart rate and rhythm. If a very fast, abnormal heart rate is detected, the device delivers electrical energy to the heart to resume beating in a normal rhythm.

Nuclear imaging— Method of producing images by detecting radiation from different parts of the body after a radioactive tracer material is administered.

Pacemaker— A small electronic device implanted under the skin that sends electrical impulses to the heart to maintain a suitable heart rate and prevent slow heart rates.

Pulmonary vein isolation— A surgical procedure used to treat atrial fibrillation.

Stress test— A test used to determine how the heart responds to stress.

Ventricles— The lower pumping chambers of the heart; the heart has two ventricles: the right and the left.

medications and fluids. General anesthesia is administered to put the patient to sleep.

In most cases, a traditional incision is made down the center of the patient’s chest, cuts through the breastbone (sternum), and the rib cage is retracted open to expose the heart. The patient is connected to a heart-lung bypass machine, also called a cardiopulmonary bypass pump, which takes over for the heart and lungs during the surgery. The heart-lung machine removes carbon dioxide from the blood and replaces it with oxygen. A tube is inserted into the aorta to carry the oxygenated blood from the bypass machine to the aorta for circulation to the body. The heart-lung machine allows the heart’s beating to be stopped so the surgeon can operate on a still heart.

Some patients may be candidates for off-pump surgery, in which the surgery is performed without the use of a heart-lung bypass machine. This is also called beating heart surgery.

The Maze surgery may be an option for some patients. The minimally invasive technique enables the surgeon to work on the heart through small chest holes called ports and other small incisions. Advantages of minimally invasive surgery over the traditional method include smaller incisions, a shorter hospital stay, a shorter recovery period, and lower costs.

During the procedure, precise incisions, also called lesions, are made in the right and left atria to isolate and stop the unusual electrical impulses from forming. The incisions form a maze through which the impulses can travel in one direction from the top of the heart to the bottom. When the heart heals, scar tissue forms and the abnormal electrical impulses can no longer travel through the heart.

These energy sources may be used during the procedure:

• Radiofrequency: A radiofrequency energy catheter is used to create the incisions or lesions in the heart.
• Microwave: A wand-like catheter is used to direct microwave energy to create the lesions in the heart.
• Cryothermy (also called cryoablation): Very cold temperatures are transmitted through a probe (cryoprobe) to create the lesions.

When these energy sources are used, the procedure is called surgical pulmonary vein isolation.

Diagnosis/Preparation

Diagnosis of abnormal heart rhythms

A doctor may be able to detect an irregular heartbeat during a physical exam by taking the patient’s pulse. In addition, the diagnosis may be based upon the presence of certain symptoms, including:

• palpitations (feeling of skipped heartbeats or fluttering in the chest)
• pounding in the chest
• shortness of breath
• chest discomfort
• fainting
• dizziness or feeling light-headed
• weakness, fatigue, or feeling tired

Not everyone with abnormal heart rhythms will experience symptoms, so the condition may be discovered upon examination for another medical condition.

DIAGNOSTIC TESTS. Tests used to diagnose an abnormal heart rhythm or determine its cause include:

• blood tests
• chest x rays
• electrocardiogram
• ambulatory monitors such as the Holter monitor, loop recorder, and trans-telephonic transmitter
• stress test
• echocardiogram
• cardiac catheterization
• electrophysiology study (EPS)
• head-upright tilt table test
• nuclear medicine test such as a MUGA scan (multiple-gated acquisition scanning)

Preparation

During a preoperative appointment, usually scheduled within one to two weeks before surgery, the patient will receive information about what to expect during the surgery and the recovery period. The patient will usually meet the cardiologist, anesthesiologist, nurse clinicians, and surgeon during this appointment or just before the procedure.

Medication to thin the blood (blood thinner or anticoagulant) is usually given for at least three weeks before the procedure.

If the patient develops a cold, fever, or sore throat within a few days before the surgery, he or she should notify the surgeon’s office.

From midnight before the surgery, the patient should not eat or drink anything.

The morning of the procedure, the patient should take all usual medications as prescribed, with a small sip of water, unless other instructions have been given. Patients who take diabetes medications or anticoagulants should ask their doctor for specific instructions.

The patient is usually admitted to the hospital the same day the surgery is scheduled. The patient should bring a list of current medications, allergies, and appropriate medical records upon admission to the hospital.

The morning of surgery, the chest area is shaved and heart monitoring begins. The patient is given general anesthesia before the procedure, so he or she will be asleep during the procedure.

The traditional Maze procedure takes about an hour to perform, while the surgical pulmonary vein isolation procedure generally takes only a few minutes to perform. However, the preparation and recovery time add a few hours to both procedures. The total time in the operating room for each of these procedures is about three to four hours.

Aftercare

Recovery in the hospital

The patient recovers in a surgical intensive care unit for one to two days after the surgery. The patient will be connected to chest and breathing tubes, a mechanical ventilator, a heart monitor, and other monitoring equipment. A urinary catheter will be in place to drain urine. The breathing tube and ventilator are usually removed about six hours after surgery, but the other tubes usually remain in place as long as the patient is in the intensive care unit.

Drugs are prescribed to control pain and to prevent unwanted blood clotting. Daily doses of aspirin are started within six to 24 hours after the procedure.

The patient is closely monitored during the recovery period. Vital signs and other parameters such as heart sounds and oxygen and carbon dioxide levels in arterial blood are checked frequently. The chest tube is checked to ensure that it is draining properly. The patient may be fed intravenously for the first day or two.

Chest physiotherapy is started after the ventilator and breathing tube are removed. The therapy includes coughing, turning frequently, and taking deep breaths. Sometimes oxygen is delivered via a mask to help loosen and clear secretions from the lungs. Other exercises will be encouraged to improve the patient’s circulation and prevent complications from prolonged bed rest.

If there are no complications, the patient begins to resume a normal routine around the second day. This includes eating regular food, sitting up, and walking around a bit. Before being discharged from the hospital, the patient usually spends a few days under observation in a non-surgical unit. During this time, counseling is usually provided on eating right and starting a light exercise program to keep the heart healthy.

The average hospital stay after the Maze surgery is five to seven days, depending on the patient’s rate of recovery.

Recovery at home

MEDICATIONS. The doctor may prescribe anti-arrhythmic medications (such as beta-blockers, digitalis, or calcium channel blockers) to prevent the abnormal heart rhythm from returning. Some patients may need to take a diuretic for four to eight weeks after surgery to reduce fluid retention that may occur after surgery. Potassium supplements may be prescribed along with the diuretic medications. Some patients may be prescribed anticoagulant medication such as warfarin and aspirin to reduce the risk of blood clots. The medications prescribed may be adjusted over time to determine the best dosage and type of medication so the abnormal heart rhythm is adequately controlled.

INCISION AND SKIN CARE. The incision should be kept clean and dry. When the skin is healed, the incision should be washed with soapy water. The scar should not be bumped, scratched, or otherwise disturbed. Ointments, lotions, and dressings should not be applied to the incision unless specific instructions have been given.

DISCOMFORT. While the incision scar heals, which takes one to two months, it may be sore. Itching, tightness, or numbness along the incision is common. Muscle or incision discomfort may occur in the chest during activity.

LIFESTYLE CHANGES. The patient needs to make several lifestyle changes after surgery, including:

• Quitting smoking. Smoking causes damage to blood vessels, increases the patient’s blood pressure and heart rate, and decreases the amount of oxygen available in the blood.
• Managing weight. Maintaining a healthy weight, by watching portion sizes and exercising, is important. Being overweight increases the work of the heart.
• Participating in an exercise program. The cardiac rehabilitation exercise program is usually tailored for the patient, who will be supervised by fitness professionals.
• Making dietary changes. Patients should eat a lot of fruits, vegetables, grains, and non-fat or low-fat dairy products, and reduce fats to less than 30% of all calories.
• Taking medications as prescribed. Aspirin and other heart medications may be prescribed, and the patient may need to take these medications for life.
• Following up with health-care providers. An exercise test is often scheduled during one of the first follow-up visits to determine how effective the surgery was and to confirm that progressive exercise is safe. The patient needs to regularly see the physician for follow-up visits to monitor his or her recovery and control risk factors.

Risks

The Maze procedure is major surgery and patients may experience any of the normal complications associated with major surgery and anesthesia, such as the risk of bleeding, pneumonia, or infection. The risk of stroke is 1%. One common complication that has occurred early after surgery is fluid retention. However, diuretics are now prescribed to reduce the risk of this complication. To date, minimal long-term adverse effects have been reported in patients undergoing the Maze procedure.

Normal results

Full recovery from the Maze procedure takes six to eight weeks. Upon release from the hospital, the patient will feel weak because of the extended bed rest in the hospital. Within a few weeks, the patient should begin to feel stronger.

Most patients are able to drive in about three to four weeks, after receiving approval from their physician. Sexual activity can generally be resumed in three to four weeks, depending on the patient’s rate of recovery.

It takes about six to eight weeks for the sternum to heal. During this time, the patient should not perform activities that cause pressure or put weight on the breastbone or tension on the arms and chest. Pushing and pulling heavy objects (such as mowing the lawn) should be avoided and lifting objects more than 20 lbs (9 kg) is not permitted. The patient should not hold his

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

Heart surgeons specially trained in the Maze procedure should perform this procedure. The Maze procedure takes place in an operating room in a hospital. When evaluating where to have the surgery performed, the patient should find out how many Maze procedures have been performed at that facility, how many Maze procedures are performed per month, when the surgeons at that facility started performing the procedure, and what the typical outcomes or results are for their patients.

or her arms above shoulder level for a long period of time. The patient should try not to stand in one place for longer than 15 minutes. Stair climbing is permitted unless other instructions have been given.

Within four to six weeks, people with sedentary office jobs can return to work; people with physical jobs (such as construction work or jobs requiring heavy lifting) must wait longer (up to 12 weeks).

In about 30% of all patients, atrial fibrillation will recur temporarily right after surgery. This is common. Medications are usually prescribed to control atrial fibrillation after surgery. About three months after the surgery, medications are often reduced and then stopped.

In about 7-10% of patients, a permanent pacemaker is needed as a result of the procedure or sometimes due to underlying sinus node dysfunction.

About 90-95% of patients have a return of normal heart rhythm within one year after the surgery. Among U.S. surgeons reporting their data in the January 2000 issue of Seminars in Thoracic and Cardiovascular Surgery, the overall success rate of the Maze procedure is from 90-98%. Some hospitals report a 98% success rate in lone atrial fibrillation patients (those who do not have any other underlying heart conditions) undergoing the traditional Maze procedure. An 80-90% success rate has been reported for the surgical pulmonary vein isolation procedure.

Morbidity and mortality rates

The overall operative mortality for patients undergoing the Maze procedure is 3%. The mortality rate increases among patients over age 65.

QUESTIONS TO ASK THE DOCTOR

Am I a candidate for minimally invasive surgery?

• Am I a candidate for the “off-pump” surgery technique?
• Who will be performing the surgery? How many years of experience does this surgeon have? How many other Maze procedures has this surgeon performed?
• Can I take my medications the day of the surgery?
• Can I or drink the day of the surgery? If not, how long before the surgery should I stop eating or drinking?
• How long will I have to stay in the hospital after the surgery?
• After I go home from the hospital, how long will it take me to recover from surgery?
• What should I do if I experience symptoms similar to those I felt before surgery?
• What types of symptoms should I report to my doctor?
• What types of medications will I have to take after surgery?
• When will I be able I resume my normal activities, including work and driving?
• When will I find out if the surgery was successful?
• What if the surgery was not successful?
• If I have had the surgery once, can I have it again to correct future blockages?
• Will I have any pain or discomfort after the surgery? If so, how can I relieve this pain or discomfort?
• Are there any medications, foods, or activities I should avoid to prevent my symptoms from recurring?
• How often do I need to see my doctor for follow-up visits after the surgery?

Atrial fibrillation is not immediately life threatening, but it can lead to other heart rhythm problems. Follow-up data from the Framingham Heart Study and the Anti-arrhythmia Versus Implantable Defibrillators Trial have shown that atrial fibrillation is a predictor of increased mortality.

According to a 2002 study published in the New England Journal of Medicine, controlling a patient’s heart rate is as important as controlling the patient’s heart rhythm to prevent death and complications from cardiovascular causes. The study also concluded that anticoagulant therapy is important to reduce the risk of stroke and is appropriate therapy in patients who have recurring, persistent atrial fibrillation even after they received treatment.

Alternatives

Health care providers usually try to correct the heart rhythm with medication and recommend lifestyle changes and other interventional procedures such as cardioversion before recommending the Maze procedure.

Lifestyle changes often recommended to treat abnormal heart rhythms include:

• quitting smoking
• avoiding activities that prompt the symptoms of abnormal heart rhythms
• limiting alcohol intake
• limiting or not using caffeine, which may produce more symptoms in some people with abnormal heart rhythms
• avoiding stimulant-containing medications such as some cough and cold remedies

If the Maze procedure is not successful in restoring the normal heart rhythm, other treatments for abnormal heart rhythms include:

• permanent pacemakers
• implantable cardioverter-defibrillator
• ablation therapy

Resources

BOOKS

Khatri, VP and JA Asensio. Operative Surgery Manual. 1st ed. Philadelphia: Saunders, 2003.

Libby, P. et al. Braunwald’s Heart Disease. 8th ed. Philadelphia: Saunders, 2007.

Townsend, CM et al. Sabiston Textbook of Surgery. 17th ed. Philadelphia: Saunders, 2004.

PERIODICALS

Gillinov AM. “Surgical approaches for atrial fibrillation.” Medical Clinics of North America, 92 (2008): 203–215.

Khasnis A “Atrial fibrillation: A historical perspective.” Medical Clinics of North America, 92 (2008): 1–15.

ORGANIZATIONS

American College of Cardiology. Heart House. 9111 Old Georgetown Rd., Bethesda, MD 20814-1699. (800) 253-4636 ext. 694 or (301) 897-5400. http://www.acc.org.

American Heart Association. 7272 Greenville Ave., Dallas, TX 75231. (800) 242-8721 or (214) 373-6300. http://www.americanheart.org.

The Cleveland Clinic Heart Center, The Cleveland Clinic Foundation. 9500 Euclid Avenue, F25, Cleveland, OH 44195. (800) 223-2273 ext. 46697 or (216) 444-6697. http://www.clevelandclinic.org/heartcenter.

National Heart, Lung and Blood Institute. National Institutes of Health. Building 1. 1 Center Dr., Bethesda, MD 20892. E-mail: <[email protected].>. http://www.nhlbi.nih.gov.

Texas Heart Institute. Heart Information Service. P.O. Box 20345, Houston, TX 77225-0345. http://www.tmc.edu/thi.

North American Society of Pacing and Electrophysiology. 6 Strathmore Rd., Natick, MA 01760-2499. (508) 647-0100. http://www.naspe.org.

OTHER

About Atrial Fibrillation. http://www.aboutatrialfibrillation.com.

HeartCenterOnline. http://www.heartcenteronline.com.

The Heart: An Online Exploration. The Franklin Institute Science Museum. 222 North 20th Street, Philadelphia, PA, 19103. (215) 448-1200. <http://sln2.fi.edu/biosci/heart.html>.

Heart Information Network. http://www.heartinfo.org.

Heart Surgeon.com. http://www.heartsurgeon.com.

Angela M. Costello

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Mean corpuscular volume seeRed blood cell indices