Who Needs Coronary Artery Bypass Grafting?

Coronary artery bypass grafting (CABG) is only used to treat people who have severe coronary artery disease (CAD) that could lead to a heart attack.

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 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 determine if you're a candidate for CABG based on a number of factors. These include the presence and severity of CAD symptoms, the severity and location of blockages in your coronary arteries, your response to other treatments, your quality of life, and any other medical problems you may have.

In some cases, CABG may be performed on an emergency basis, such as pending or during a heart attack.

Physical Exam and Diagnostic Tests

To determine if you're a candidate for CABG, your doctor will do a physical exam that involves checking your cardiovascular system, focusing on heart, lungs, and pulse. Your doctor also will ask you about any symptoms you have, such as chest pain or shortness of breath, and how long, how often, and how severe they are.

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

• EKG (electrocardiogram). An EKG is a simple test that detects and records the electrical activity of the heart. This test is used to help detect and locate the source of heart problems. An EKG shows how fast the heart is beating, whether the heart's rhythm is steady or irregular, where in the heart the electrical activity starts, and whether the electrical activity is traveling through the heart in a normal way.
• Stress test. Some heart problems are easier to diagnose when your heart is working harder and beating faster than when it's at rest. During stress testing, you exercise (or are given medicine if you're unable to exercise) to make your heart work harder and beat faster while heart tests are performed.
• During exercise stress testing, your blood pressure and EKG readings are monitored while you walk or run on a treadmill or pedal a bicycle. Other heart tests, such as nuclear heart scanning or echocardiography, also can be done at the same time. These would be ordered if your doctor needs more detailed information on blood flow and the heart's pumping action than the exercise stress test can provide.
• If you are unable to exercise, a medicine can be injected through an intravenous line (IV) into your bloodstream to make your heart work harder and beat faster, as if you are exercising on a treadmill or bicycle. Nuclear heart scanning or echocardiography is then usually done.
• During nuclear heart scanning, radioactive tracer is injected into your bloodstream, and a special camera shows the flow of blood through your heart and arteries. Echocardiography uses sound waves to show blood flow through the chambers and valves of your heart and to show how well your heart pumps.
• Your doctor also may order two newer tests along with stress testing if more information is needed about how well your heart works. These new tests are magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning of the heart. MRI shows detailed images of the structures and beating of your heart, which may help your doctor better assess if parts of your heart are weak or damaged. PET scanning shows the level of metabolic activity in different areas of your heart. This can help your doctor determine if enough blood is flowing to the areas of your heart. A PET scan can show decreased blood flow caused by disease or damaged muscles that may not be detected by other scanning methods.
• Echocardiogram. This test uses sound waves to create a moving picture of your heart. Echocardiogram provides information about the size and shape of your heart and how well your heart chambers and valves are functioning. The test also can identify areas of poor blood flow to the heart, areas of heart muscle that are not contracting normally, and previous injury to the heart muscle caused by poor blood flow.
• There are several different types of echocardiograms, including a stress echocardiogram. During this test, an echocardiogram is done both before and after your heart is stressed either by having you exercise or by injecting a medicine into your bloodstream that makes your heart beat faster and work harder. A stress echocardiogram is usually done to find out if you have decreased pumping action of your heart (CAD).
• Angiography. Angiography uses a special dye injected into the bloodstream to outline the insides of arteries on x-ray pictures. An angiogram shows the location and severity of blockages in blood vessels.

Other Considerations

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

• History and past treatment of heart disease, including surgeries, procedures, or medicines
• History of other diseases and conditions
• Age and general health
• Family history of CAD, 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 are often tried.

A procedure called coronary angioplasty (also called balloon angioplasty) may be tried. During this procedure, a thin tube with a balloon or other device on the end is threaded through a blood vessel in your groin (upper thigh) or arm up to the narrowed or blocked coronary artery. Once in place, the balloon is inflated to push the plaque against the wall of the artery, widening the artery and restoring the flow of blood through it. In many cases, after the initial balloon angioplasty, a tiny mesh tube called a stent is inserted permanently in the area to keep the artery open.