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 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, shortness of breath, and, in some cases, a 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.
Overview
CABG is the most common type of open-heart surgery in the United States. Doctors called cardiothoracic 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 in other ways, such as with lifestyle changes, medicines, and a procedure called angioplasty. 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 a heart attack has damaged it
- 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 ten 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 reasonably 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 severe coronary 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 significant 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 several 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, 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 reduced blood flow to the heart, areas of the heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by reduced 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 end is threaded through a blood vessel to the narrowed or blocked the 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 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.