Topic Overview
During coronary artery bypass graft (CABG) surgery, your surgeon
will use a healthy blood vessel from another part of your body to create an
alternate route, or bypass, around narrowed or blocked sections of your
coronary arteries. This bypass surgery allows more blood to reach your heart
muscle.
Your medical team will monitor your vital signs, such as blood
pressure, heart rhythm, and blood oxygen levels.
Opening the chest
Your surgeon will make a cut, or incision, in the middle or side of your chest. He or she may cut through your breastbone and spread apart your rib cage. The rib cage is opened
to expose all internal organs within your chest cavity (a process called a
sternotomy). Your surgeon next cuts through the saclike lining that protects
the heart (pericardium) to access the heart itself. Your coronary arteries lie
on both the front and back surfaces of the heart.
Harvesting a vein to use as a graft blood vessel
The surgeon can remove a
piece of healthy blood vessel from these places in the body:
- The inside of your leg
- Your
forearm
- Just behind your chest wall
These blood vessels will be used as bypass grafts around narrowed or
blocked portions of your coronary arteries.
Leg and arm. While your chest cavity is being
opened, the surgeon's assistant may begin to remove, or harvest, a healthy
blood vessel from your arm (radial artery) or leg (saphenous vein).
Using a chest-wall artery for a graft vessel
Besides your saphenous vein and radial arteries, other blood vessels
can be used as bypass grafts. In fact, given that they are located close to the
heart and coronary arteries, the left and right internal mammary arteries (LIMA
and RIMA) are actually favored by many doctors. These arteries have two
distinct advantages besides their location:
- Mammary arteries are already attached to the main artery
(the aorta). This means that only its other end must be disconnected and
grafted onto the diseased coronary artery.
- Because they are
arteries, the LIMA and RIMA are more accustomed to a forceful blood flow than a
saphenous vein. (Veins carry blood from the body back to the heart and aren't
under as much pressure.) So the LIMA or RIMA may prove to be more
durable in the years after your surgery.
Putting you on the heart-lung bypass machine
After your coronary arteries have been exposed and a usable blood
vessel segment has been harvested, your surgical team may
place you on a heart-lung bypass machine. Alternately,
your surgical team may do the operation while your heart is beating. If
you are placed on the heart-lung bypass machine, your heart will be temporarily
stopped during the surgery so your surgeon can perform surgery on
your coronary arteries. The heart-lung bypass machine does the work of your
heart and lungs so that all the parts of your body still receive the
oxygen-rich blood they need to survive.
While the ventilator physically inflates and deflates your lungs, the
bypass machine performs the lungs' main job of adding oxygen and removing
unwanted gases from your blood. Also, the machine circulates that blood
through your body.
After the heart-lung machine has been set up, the blood flowing from
your heart to the rest of your body will be stopped by clamping the aorta and
will be rerouted through the heart-lung bypass machine. The surgeon stops your heartbeat with a medicine. Your heart will not beat again until the new
grafts have been put in place.
Bypassing your diseased coronary arteries
Your surgeon
will start to operate on the coronary arteries. The harvested vein
in the sterile saline solution is cut into appropriate lengths. Your surgeon
will attach one end of the blood vessel to the aorta and the other end onto a portion of the coronary artery past the
location in the artery where there is narrowing or blockage.
In the case of the LIMA or RIMA, one end remains attached to your
chest wall and the other end is connected to the coronary artery. Regardless of
which type of blood vessel is used, oxygen-rich blood is rerouted around the
narrowed or blocked section of the coronary artery and into a healthy section
where it can feed into the heart muscle.
Preventing blood loss during surgery
During the surgery, blood may spill into your chest cavity as small
blood vessels are cut. To prevent this blood from interfering with surgery, a
nurse or surgeon's assistant will use a suction device (which looks like a
large plastic straw) to suck up the blood. The blood is then recycled back to the body. Despite this effort,
though, about half of the people who have CABG surgery end up needing a blood
transfusion.
Restarting your heart
If you are on the heart-lung bypass machine, your doctor
will restart your heart. After your bypass grafts have been sewn in
place with strong stitches (sutures), your doctor will take the clamp off of
your aorta. This will allow blood to flow to your heart, and the heart will
typically start to beat again.
When your heart starts to beat again, you will be taken off the
heart-lung bypass machine. Your surgeon may then apply a small electric shock,
or your anesthesiologist may administer another medicine to help your heart
muscle regain its natural rhythm.
Closing your chest cavity
Prior to closing up your sternum, your surgeon will place several small tubes inside your chest cavity, with one end exiting your body through an incision in
your upper abdomen. These tubes allow drainage of any extra fluids from your
chest. Your surgeon will then close your rib cage and use metal wires to bring
the two halves of your sternum back together.
Finally, your surgeon will sew the soft tissues and muscles in your
chest together with extra-strong stitches, or sutures. Surgery without
complications usually takes 3 to 6 hours, depending on how many coronary
arteries are bypassed.
Final thoughts
Although the CABG procedure is considered a relatively safe
procedure, it also involves certain risks. It is important that you educate
yourself about the
risks of CABG surgery beforehand and talk with your
surgeon about how your current health condition will affect your risk for
complications.