Coronary artery bypass grafting (CABG) is a type of surgery that improves blood flow to the heart. Surgeons use CABG to treat people who have severe coronary heart disease (CHD).
CHD is a disease in which a waxy substance called plaque (plak) builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart.
Over time, plaque can harden or rupture (break open). Hardened plaque narrows the coronary arteries and reduces the flow of oxygen-rich blood to the heart. This can cause chest pain or discomfort called angina (an-JI-nuh or AN-juh-nuh).
If the plaque ruptures, a blood clot can form on its surface. A large blood clot can mostly or completely block blood flow through a coronary artery. This is the most common cause of a heart attack. Over time, ruptured plaque also hardens and narrows the coronary arteries.
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 path for oxygen-rich blood to flow to the heart muscle.
Surgeons can bypass multiple coronary arteries during one surgery.
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.
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.
However, CABG isn’t the only treatment for CHD. Other treatment options include lifestyle changes, medicines, and a procedure called coronary angioplasty (AN-jee-oh-plas-tee).
Angioplasty is a nonsurgical procedure that opens blocked or narrow coronary arteries. During angioplasty, a stent might be placed in a coronary artery to help keep it open. A stent is a small mesh tube that supports the inner artery wall.
CABG or angioplasty may be options if you have severe blockages in your large coronary arteries, especially if your heart’s pumping action has already grown weak.
CABG also may be an option if you have blockages in the heart that can’t be treated with angioplasty. In this situation, CABG may work better than other types of treatment.
The goals of CABG may include:
- Improving your quality of life and reducing 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
There are several types of coronary artery bypass grafting (CABG). Your doctor will recommend the best option for you based on your needs.
Traditional Coronary Artery Bypass Grafting
Traditional CABG is 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; a heart-lung bypass machine keeps 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. Sometimes 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 sometimes is called beating heart bypass grafting.
Minimally Invasive Direct Coronary Artery Bypass Grafting
This type of surgery differs from traditional CABG because the chest bone isn’t opened to reach the heart. Instead, several small cuts are made on the left side of the chest between the ribs. This type of surgery mainly is used to bypass blood vessels at the front of the heart.
Minimally invasive bypass grafting is a fairly new procedure. It isn’t right for everyone, 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 might be used during or after a heart attack to treat 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 your large coronary (heart) arteries, especially if your heart’s pumping action has already grown weak.
CABG also might be a treatment option if you have blockages in your coronary arteries that can’t be treated with angioplasty.
Your doctor will decide whether you’re a candidate for CABG based on factors such as:
- 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
Physical Exam and Diagnostic Tests
To find out whether you’re a candidate for CABG, your doctor will give you a physical exam. He or she will check your heart, lungs, and pulse.
Your doctor also may 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, as well as how severe they are.
Your doctor will recommend tests to find out which arteries are clogged, how much they’re clogged, and whether you have any heart damage.
An EKG is a simple test that detects and records your heart’s electrical activity. The test shows how fast the heart is beating and its rhythm (steady or irregular). An EKG also records the strength and timing of electrical signals as they pass through each part of the heart.
An EKG can show signs of heart damage due to CHD and signs of a previous or current heart attack.
Echocardiography (echo) uses sound waves to create a moving picture of your heart. The test shows the size and shape of your heart and how well your heart chambers and valves are working.
Echo also can show 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.
Some heart problems are easier to diagnose when your heart is working hard and beating fast.
During stress testing, you exercise to make your heart work hard and beat fast while heart tests are done. If you can’t exercise, you may be given medicine to raise your heart rate.
The heart tests done during stress testing may include nuclear heart scanning, echo, and positron emission tomography (PET) scanning of the heart.
Coronary Angiography and Cardiac Catheterization
Coronary angiography (an-jee-OG-rah-fee) is a test that uses dye and special x rays to show the insides of your coronary arteries.
To get the dye into your coronary arteries, your doctor will use a procedure calledcardiac catheterization (KATH-eh-ter-ih-ZA-shun).
A thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck. The tube is threaded into your coronary arteries, and the dye is released into your bloodstream.
Special x rays are taken while the dye is flowing through the coronary arteries. The dye lets your doctor study blood flow through the heart and blood vessels. This helps your doctor find blockages that can cause a heart attack.
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
Your doctor may recommend medicines and other medical procedures before CABG. For example, he or she may prescribe medicines to lower your cholesterol and blood pressure and improve blood flow through your coronary arteries.
Angioplasty also might be tried. During this procedure, a thin, flexible tube with a balloon at its tip is threaded through a blood vessel to the narrow or blocked coronary artery.
Once in place, the balloon is inflated, pushing the plaque against the artery wall. This creates a wider path for blood to flow to the heart.
Sometimes a stent is placed in the artery during angioplasty. A stent is a small mesh tube that supports the inner artery wall.