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Coronary Artery Bypass Grafting (CABG)

Why Is Bypass Surgery Done?

A doctor performs bypass surgery to route blood around–or "bypass"–arteries that have become clogged by plaque. Plaque forms when fats in the blood build up in the arteries. Plaque buildup can eventually slow or block the flow of blood in arteries. When blood flow is blocked in the coronary arteries, which are on the surface of your heart, your heart muscle does not get the oxygen-rich blood that it needs. A heart attack can result.

Bypass surgery restores blood flow to the heart, which can:

  • Lower the risk of a heart attack or other heart problems
  • Relieve symptoms (for example, chest pain or shortness of breath)
  • Help patients return to normal activities

What Happens During Bypass Surgery?

Whether your doctor performs traditional bypass or beating heart bypass, many of the surgical steps are the same.

Surgery begins with an incision in your breastbone to expose your heart. Next the doctor takes–or "harvests"–part of a healthy blood vessel from elsewhere in your body. Sometimes a doctor takes a vessel from the chest area to avoid making another incision. Other times a doctor takes a vessel from your leg. It's okay to remove pieces of these blood vessels for bypass because other vessels take over for them.

After making the heart still, the doctor then sews–or "grafts"–the new blood vessel onto your blocked heart artery. Blood then flows through the healthy vessel, around the blocked part of the artery. Finally, the doctor closes the chest incision.

Two Types of Bypass Surgery

So how do the two types of bypass surgery differ? The main difference is the method the doctor uses to make your heart still during the surgery. The heart must be still enough for the doctor to do the delicate work of sewing the healthy vessel onto your heart.

With traditional bypass, the doctor uses the heart-lung machine and operates on a completely still heart. With beating heart bypass, the doctor uses a special tool to hold just part of your heart still. The rest of your heart continues to beat, so you don't need the heart-lung machine.

Traditional Bypass: Using the Heart-Lung Machine

During traditional bypass surgery, your doctor gives you medication to stop your heart completely. Your blood then flows through a heart-lung machine. The machine allows blood to continue flowing throughout your body, except through your heart, while your doctor sews the new blood vessel in place.

The heart-lung machine has two important functions. As its name suggests, the machine does the job of the:

  • Heart–by pumping the blood back into, and throughout, the body
  • Lungs–by adding oxygen to the blood before it is pumped throughout the body

If you have more than one blocked artery, the doctor can bypass each one during the same surgery. When the surgery is over, the doctor uses electrical shocks to restart the heart. The heart-lung machine is then disconnected and your heart pumps blood again on its own.

A Newer Option: Beating Heart Bypass

With beating heart bypass, the doctor uses a surgical tool to stabilize a small part of your heart.  The tool holds this small part of your heart still while the doctor sews the healthy blood vessel(s) into place. Since the rest of your heart beats normally, you don't need the heart-lung machine.

As in traditional bypass surgery, if you have more than one blocked artery, the doctor can bypass each one during the same surgery. But in beating heart bypass, the doctor uses the special tool to hold different parts of the heart still, one at a time. For some high-risk patients, beating heart bypass may further reduce the risk of complications.