Coronary Artery Bypass Grafting (CABG)

Coronary artery bypass grafting (CABG) is a type of surgery that improves blood flow to the heart. It's used for people who have severe coronary heart disease (CHD), also called coronary artery disease.

CHD is a condition in which a substance called plaque (plak) builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart. Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood.

Plaque can narrow or block the coronary arteries and reduce blood flow to the heart muscle. If the blockage is severe, angina (an-JI-nuh or AN-juh-nuh), shortness of breath, and, in some cases, heart attack can occur. (Angina is chest pain or discomfort.)

CABG is one treatment for CHD. During CABG, a healthy artery or vein from the body is connected, or grafted, to the blocked coronary artery. The grafted artery or vein bypasses (that is, goes around) the blocked portion of the coronary artery.

This creates a new passage, and oxygen-rich blood is routed around the blockage to the heart muscle.

Coronary Artery Bypass Grafting

Figure A shows the location of the heart. Figure B shows how vein and artery bypass grafts are attached to the heart.

As many as four major blocked coronary arteries can be bypassed during one surgery.

Overview

CABG is the most common type of open-heart surgery in the United States. Doctors called cardiothoracic (KAR-de-o-tho-RAS-ik) surgeons do this surgery.

Other Names for Coronary Artery Bypass Grafting

• Bypass surgery
• Coronary artery bypass surgery
• Heart bypass surgery

CHD isn't always treated with CABG. Many people who have CHD can be treated other ways, such as with lifestyle changes, medicines, and a procedure calledangioplasty (AN-jee-oh-plas-tee). During angioplasty, a small mesh tube called astent may be placed in an artery to help keep it open.

CABG or angioplasty with stent placement may be options if you have severe blockages in your large coronary arteries, especially if your heart's pumping action has already been weakened.

CABG also may be an option if you have blockages in the heart that can't be treated with angioplasty. In this situation, CABG is considered more effective than other types of treatment.

If you're a candidate for CABG, the goals of having the surgery include:

• Improving your quality of life and decreasing angina and other CHD symptoms
• Allowing you to resume a more active lifestyle
• Improving the pumping action of your heart if it has been damaged by a heart attack
• Lowering the risk of a heart attack (in some patients, such as those who have diabetes)
• Improving your chance of survival

You may need repeat surgery if the grafted arteries or veins become blocked, or if new blockages develop in arteries that weren't blocked before. Taking medicines as prescribed and making lifestyle changes as your doctor recommends can lower the chance of a graft becoming blocked.

In people who are candidates for the surgery, the results usually are excellent. Following CABG, 85 percent of people have significantly reduced symptoms, less risk of future heart attacks, and a decreased chance of dying within 10 years.

Types of Coronary Artery Bypass Grafting

Traditional Coronary Artery Bypass Grafting

This is the most common type of coronary artery bypass grafting (CABG). It's used when at least one major artery needs to be bypassed.

During the surgery, the chest bone is opened to access the heart. Medicines are given to stop the heart, and a heart-lung bypass machine is used to keep blood and oxygen moving throughout the body during surgery. This allows the surgeon to operate on a still heart.

After surgery, blood flow to the heart is restored. Usually, the heart starts beating again on its own. In some cases, mild electric shocks are used to restart the heart.

Off-Pump Coronary Artery Bypass Grafting

This type of CABG is similar to traditional CABG because the chest bone is opened to access the heart. However, the heart isn't stopped, and a heart-lung bypass machine isn't used. Off-pump CABG is sometimes called beating heart bypass grafting.

Minimally Invasive Direct Coronary Artery Bypass Grafting

This surgery is similar to off-pump CABG. However, instead of a large incision (cut) to open the chest bone, several small incisions are made on the left side of the chest between the ribs.

This type of surgery mainly is used for bypassing the blood vessels in front of the heart. It's a fairly new procedure that's done less often than the other types of CABG.

This type of CABG isn't for everybody, especially if more than one or two coronary arteries need to be bypassed.

Who Needs Coronary Artery Bypass Grafting?

Coronary artery bypass grafting (CABG) is used to treat people who have severecoronary heart disease (CHD) that could lead to a heart attack. CABG also may be used to treat people who have heart damage following a heart attack but still have blocked arteries.

Your doctor may recommend CABG if other treatments, such as lifestyle changes or medicines, haven't worked. He or she also may recommend CABG if you have severe blockages in the large coronary (heart) arteries that supply a major part of the heart muscle with blood-especially if your heart's pumping action has already been weakened.

CABG also may be a treatment option if you have blockages in the heart that can't be treated with angioplasty.

Your doctor will decide whether you're a candidate for CABG based on a number of factors, including:

• The presence and severity of CHD symptoms
• The severity and location of blockages in your coronary arteries
• Your response to other treatments
• Your quality of life
• Any other medical problems you have

CABG may be done on an emergency basis, such as during a heart attack.

Physical Exam and Diagnostic Tests

To decide whether you're a candidate for CABG, your doctor will do a physical exam. He or she will check your cardiovascular system, focusing on your heart, lungs, and pulse.

Your doctor also will ask you about any symptoms you have, such as chest pain or shortness of breath. He or she will want to know how often and for how long your symptoms occur and how severe they are.

Tests will be done to find out which arteries are clogged, how much they're clogged, and whether there's any heart damage.

EKG (Electrocardiogram)

An EKG is a simple test that detects and records your heart's electrical activity. This test is used to help detect and locate the source of heart problems.

An EKG shows how fast your heart is beating and its rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through each part of your heart.

Stress Test

Some heart problems are easier to diagnose when your heart is working hard and beating fast. During stress testing, you exercise (or are given medicine if you're unable to exercise) to make your heart work hard and beat fast while heart tests are done.

These tests may include nuclear heart scanning, echocardiography, and magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning of the heart.

Echocardiography

Echocardiography (EK-o-kar-de-OG-ra-fee), or echo, uses sound waves to create a moving picture of your heart. The test provides information about the size and shape of your heart and how well your heart's chambers and valves are working.

The test also can identify areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by poor blood flow.

There are several types of echo, including stress echo. This test is done both before and after a stress test. A stress echo usually is done to find out whether you have decreased blood flow to your heart, a sign of CHD.

Coronary Angiography

Coronary angiography uses dye and special x rays to show the insides of your coronary (heart) arteries. During the test, a long, thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck.

The tube is then threaded into your coronary arteries, and the dye is injected into your bloodstream. Special x rays are taken while the dye is flowing through your coronary arteries.

The dye lets your doctor study the flow of blood through your heart and blood vessels. This helps your doctor find blockages that can cause a heart attack.

Other Considerations

When deciding whether you're a candidate for CABG, your doctor also will consider your:

• History and past treatment of heart disease, including surgeries, procedures, and medicines
• History of other diseases and conditions
• Age and general health
• Family history of CHD, heart attack, or other heart diseases

Medicines and other medical procedures may be tried before CABG. Medicines that lower cholesterol levels and blood pressure and improve blood flow through the coronary arteries often are tried.

Angioplasty also may be tried. During this procedure, a thin tube with a balloon or other device on the end is threaded through a blood vessel to the narrowed or blocked coronary artery.

Once in place, the balloon is inflated to push the plaque against the wall of the artery. This widens the artery and restores the flow of blood. Often, a small mesh tube called a stent is placed in the artery to keep it open after the procedure.

What To Expect Before Coronary Artery Bypass Grafting

Tests may be done to prepare you for coronary artery bypass grafting (CABG). For example, you may have blood tests, an EKG (electrocardiogram),echocardiography, a chest x ray, cardiac catheterization, and coronary angiography.

Your doctor will give you specific instructions about how to prepare for surgery. He or she will advise you about what to eat or drink, what medicines to take, and what activities to stop (such as smoking). You'll likely be admitted to the hospital on the same day as the surgery.

If tests for coronary heart disease show that you have severe blockages in your coronary (heart) arteries, your doctor may admit you to the hospital right away. You may have CABG that day or the day after.

What To Expect During Coronary Artery Bypass Grafting

Coronary artery bypass grafting (CABG) requires a team of experts. A cardiothoracic surgeon does the surgery with support from an anesthesiologist, perfusionist (heart-lung bypass machine specialist), other surgeons, and nurses.

There are several types of CABG. They range from traditional surgery in which the chest is opened to reach the heart, to nontraditional surgery in which small incisions (cuts) are made to bypass the blocked or narrowed artery.

Traditional Coronary Artery Bypass Grafting

This type of surgery usually lasts 3 to 5 hours, depending on the number of arteries being bypassed. Numerous steps take place during traditional CABG.

You'll be under general anesthesia (AN-es-THE-ze-a) for the surgery. The term "anesthesia" refers to a loss of feeling and awareness. General anesthesia temporarily puts you to sleep.

During the surgery, the anesthesiologist checks your heartbeat, blood pressure, oxygen levels, and breathing. A breathing tube is placed in your lungs through your throat. The tube is connected to a ventilator (a machine that helps you breathe).

An incision is made down the center of your chest. The chest bone is then cut and your ribcage is opened so that the surgeon can get to your heart.

Medicines are used to stop your heart, which allows the surgeon to operate on it while it's not beating. You're also given medicines to protect your heart function during the time that it's not beating.

A heart-lung bypass machine keeps oxygen-rich blood moving throughout your body during the surgery. For more information about heart-lung bypass machines, including an illustration, go to "What To Expect During Heart Surgery."

An artery or vein is taken from your body-for example, from your chest or leg-and prepared to be used as a graft for the bypass. In surgery with several bypasses, both artery and vein grafts are commonly used.

• Artery grafts. These grafts are much less likely than vein grafts to become blocked over time. The left internal mammary artery most often is used for an artery graft. It's located inside the chest, close to the heart. Arteries from the arm or other places in the body are sometimes used as well.
• Vein grafts. Although veins are commonly used as grafts, they're more likely than artery grafts to develop plaque and become blocked over time. The saphenous vein-a long vein running along the inner side of the leg-is typically used.

After the grafting is done, blood flow to your heart is restored. Usually, the heart starts beating again on its own. In some cases, mild electric shocks are used to restart the heart. You're then disconnected from the heart-lung bypass machine. Tubes are inserted into your chest to drain fluid.

The surgeon uses wires to close your chest bone (much like how a broken bone is repaired). The wires stay in your body permanently. After your chest bone heals, it will be as strong as it was before the surgery.

Stitches or staples are used to close the skin incision. The breathing tube is removed when you're able to breathe without it.

Nontraditional Coronary Artery Bypass Grafting

Nontraditional CABG includes off-pump CABG and minimally invasive CABG.

Off-Pump Coronary Artery Bypass Grafting

This type of surgery can be used to bypass any of the coronary (heart) arteries. Off-pump CABG also is called beating heart bypass grafting because the heart isn't stopped and a heart-lung bypass machine isn't used. Instead, the part of the heart where grafting is being done is steadied with a mechanical device.

Minimally Invasive Direct Coronary Artery Bypass Grafting

There are several types of minimally invasive direct coronary artery bypass (MIDCAB) grafting. These types of surgery differ from traditional bypass surgery. They only require small incisions rather than opening the chest bone to get to the heart. These procedures sometimes use a heart-lung bypass machine.

MIDCAB procedure. This procedure is used when only one or two coronary arteries need to be bypassed. A series of small incisions is made between your ribs on the left side of your chest, directly over the artery to be bypassed.

The incisions usually are about 3 inches long. (The incision made in traditional CABG is at least 6 to 8 inches long.) The left internal mammary artery most often is used for the graft. A heart-lung bypass machine isn't used during this procedure.

Port-access coronary artery bypass procedure. This procedure is done through small incisions (ports) made in your chest. Artery or vein grafts are used. A heart-lung bypass machine is used during this procedure.

Robot-assisted technique. This type of procedure allows for even smaller, keyhole-sized incisions. A small video camera is inserted in one incision to show the heart, while the surgeon uses remote-controlled surgical instruments to do the surgery. A heart-lung bypass machine is sometimes used during this procedure.

What To Expect After Coronary Artery Bypass Grafting

Recovery in the Hospital

After surgery, you'll typically spend 1 or 2 days in an intensive care unit (ICU). Your heart rate, blood pressure, and oxygen levels will be checked regularly during this time.

An intravenous line (IV) will likely be inserted into a vein in your arm. Through the IV line, you may get medicines to control blood circulation and blood pressure. You also will likely have a tube in your bladder to drain urine and a tube to drain fluid from your chest.

You may receive oxygen therapy (oxygen given through nasal prongs or a mask) and a temporary pacemaker while in the ICU. A pacemaker is a small device that's placed in the chest or abdomen to help control abnormal heart rhythms.

Your doctor may recommend that you wear compression stockings on your legs as well. These stockings are tight at the ankle and become looser as they go up the leg. This creates gentle pressure up the leg. The pressure keeps blood from pooling and clotting.

While in the ICU, you'll also have bandages on your chest incision (cut) and on the areas where an artery or vein was removed for grafting.

After you leave the ICU, you'll be moved to a less intensive care area of the hospital for 3 to 5 days before going home.

Recovery at Home

Your doctor will give you specific instructions for recovering at home, especially concerning:

• How to care for your healing incisions
• How to recognize signs of infection or other complications
• When to call the doctor right away
• When to make followup appointments

You also may get instructions on how to deal with common side effects from surgery. Side effects often go away within 4 to 6 weeks after surgery, but may include:

• Discomfort or itching from healing incisions
• Swelling of the area where an artery or vein was removed for grafting
• Muscle pain or tightness in the shoulders and upper back
• Fatigue (tiredness), mood swings, or depression
• Problems sleeping or loss of appetite
• Constipation
• Chest pain around the site of the chest bone incision (more frequent with traditional CABG)

Full recovery from traditional CABG may take 6 to 12 weeks or more. Less recovery time is needed for nontraditional CABG.

Your doctor will tell you when you can start physical activity again. It varies from person to person, but there are some typical timeframes. Most people can resume sexual activity within about 4 weeks and driving after 3 to 8 weeks.

Returning to work after 6 weeks is common unless your job involves specific and demanding physical activity. Some people may need to find less physically demanding types of work or work a reduced schedule at first.

Ongoing Care

Care after surgery may include periodic checkups with doctors. During these visits, tests may be done to see how your heart is working. Tests may include EKG(electrocardiogram), stress testing, echocardiography, and cardiac CT.

CABG is not a cure for coronary heart disease (CHD). You and your doctor may develop a treatment plan that includes lifestyle changes to help you stay healthy and reduce the chance of CHD getting worse.

Lifestyle changes may include making changes to your diet, quitting smoking, doing physical activity regularly, and lowering and managing stress.

Your doctor also may refer you to cardiac rehabilitation (rehab). Cardiac rehab is a medically supervised program that helps improve the health and well-being of people who have heart problems.

Rehab programs include exercise training, education on heart healthy living, and counseling to reduce stress and help you return to an active life. Doctors supervise these programs, which may be offered in hospitals and other community facilities. Talk to your doctor about whether cardiac rehab might benefit you.

Taking medicines as prescribed also is an important part of care after surgery. Your doctor may prescribe medicines to manage pain during recovery; lower cholesterol and blood pressure; reduce the risk of blood clots forming; manage diabetes; or treat depression. 

What Are the Risks of Coronary Artery Bypass Grafting?

Although complications from coronary artery bypass grafting (CABG) are uncommon, the risks include:

• Wound infection and bleeding
• Reactions to anesthesia
• Fever
• Pain
• Stroke, heart attack, or even death

Some patients develop a fever associated with chest pain, irritability, and decreased appetite. This is due to inflammation involving the lung and heart sac.

This complication sometimes is seen 1 to 6 weeks after surgeries that involve cutting through the pericardium (the outer covering of the heart). This reaction usually is mild. However, some patients may develop fluid buildup around the heart that requires treatment.

Memory loss and other changes, such as problems concentrating or thinking clearly, may occur in some people.

These changes are more likely to occur in people who are older, who have high blood pressure or lung disease, or who drink excessive amounts of alcohol. These side effects often improve several months after surgery.

Use of a heart-lung bypass machine increases the risk of blood clots forming in your blood vessels. Clots can travel to the brain or other parts of the body and block the flow of blood, which may cause a stroke or other problems. Recent technical improvements in heart-lung bypass machines are helping reduce the risk of blood clots forming.

In general, the risk of complications is higher if CABG is done in an emergency situation (for example, during a heart attack), if you're older than 70, or if you have a history of smoking.

Your risk also is higher if you have other diseases or conditions, such as diabetes, kidney disease, lung disease, or peripheral arterial disease.