CABG (coronary artery bypass graft) - What happens during coronary artery bypass surgery

Before your coronary artery bypass graft (CABG), your surgeon will discuss every aspect of the procedure with you.

This will give you the opportunity to ask any questions to make sure you understand the procedure fully.

Because the procedure is performed using a general anaesthetic (where you are asleep during the operation), you must not eat or drink for at least six hours before the operation. You may be able to have occasional sips of water until two hours before the operation.

During the operation

CABG surgery usually lasts three to six hours. However, it may take longer depending on how many blood vessels are being grafted.

Blood vessels can be taken from your leg (saphenous vein), inside your chest (internal mammary artery) or your arm (radial artery). Other blood vessels in these areas are able to compensate for the loss of these blood vessels after the operation.

The number of vessels used will depend on how severe your coronary heart disease is and how many of the coronary blood vessels have become narrowed. Most people will need three or four vessels grafted. If you need two, three or four grafts, you may hear your operation referred to as a 'double', 'triple' or 'quadruple' bypass.

One of the graft vessels is usually your internal mammary artery. Surgeons prefer to use this vessel because it does not narrow over time, unlike the blood vessels taken from your leg or arm.

Once all the graft vessels have been removed, your surgeon will make a cut (incision) down the middle of your chest so they can divide your breastbone (sternum) and access your heart.

During the procedure, your blood may be re-routed to a heart-lung bypass machine. This takes over from your heart and lungs, pumping blood and oxygen through your body. Your heart will be temporarily stopped using medication while your surgeon attaches the new grafts to divert the blood supply around the blocked artery.

After the grafts have been attached, your heart will be started again using controlled electrical shocks. Your sternum will then be fixed together using permanent metal wires and the skin on your chest sewn up using dissolvable stitches.

Read about recovering from a coronary artery bypass graft.

Newer surgical techniques

Off-pump coronary artery bypass surgery (OPCAB)

More surgeons are now performing off-pump coronary artery bypass surgery (OPCAB), which is a variation of the conventional CABG procedure.

A CABG is often described as on-pump surgery as it involves using a heart-lung bypass machine to pump blood and oxygen around your body during the procedure, while the heart is temporarily stopped.

During the OPCAB, your heart is still beating while the new blood vessel grafts are attached and a heart-lung bypass machine is not used.

According to the National Institute for Health and Care Excellence (NICE), this procedure works as well as a coronary artery bypass using a pump.

The benefits of an OPCAB are:

• it often takes less time to perform than a CABG
• it can reduce your chance of bleeding during the surgery
• you may be less likely to develop certain serious complications after surgery, such as a stroke
• your stay in hospital is usually shorter

The main disadvantage is that OPCAB is more technically demanding, as the grafted vessels have to be delicately connected while the heart is beating. This means that OPCAB may be too difficult to perform if a large number of blood vessels need to be grafted.

For the same reason, if emergency surgery is required, there may not be ready access to a surgeon with the training required to perform an OPCAB.

Read the NICE guidelines on off-pump coronary artery bypass grafting.

Endoscopic saphenous vein harvesting (ESVH)

Endoscopic saphenous vein harvesting (ESVH) is a new method of removing the veins from your legs. Rather than making a large incision in your leg, the surgeon makes a number of small incisions near your knee. This is known as 'keyhole' surgery.

A special device known as an endoscope is then inserted into the incision. An endoscope is a thin, long flexible tube that contains a light source and a video camera, so that images of the inside of your body can be relayed to an external monitor (screen).

The endoscope allows the surgeon to locate your saphenous vein. Surgical instruments can then be passed along the endoscope to remove a section of the vein. Nearby tissue is then sterilised with antibiotic fluid and the incision is healed.

The main advantages of this technique are that there is likely to be less scarring and your leg will usually heal more quickly after the operation. However, as this is a relatively new technique, there are uncertainties about how well the grafts work in the years after the procedure.

Read the NICE guidelines on endoscopic saphenous vein harvest for coronary artery bypass grafting.

Totally endoscopic robotically assisted coronary artery bypass (TECAB) grafting

Another new technique in heart surgery is totally endoscopic robotically assisted coronary artery bypass (TECAB) grafting, which is a minimally invasive (keyhole) way of performing a heart bypass.

During a TECAB grafting procedure, the surgeon deflates your lungs and makes a number of small incisions between your ribs. Robotic arms, controlled by the surgeon, are used to carry out the surgery. An endoscope is attached to the robotic arms so the surgeon can see inside your body and view the results of the surgery on a screen.

TECAB grafting can be carried out using a heart-lung bypass machine or it can be done 'off-pump'.

With this type of surgery there are lower rates of wound infection, minimal scarring and a faster recovery time. However, as this is a new technique that has only been carried out on a small number of people, it is difficult to assess how effective and safe it is in the short and long term, and how the outcomes compare with other types of surgery.

If you are considering having a totally endoscopic robotically assisted CABG, it is important you understand that there are still uncertainties about how safe the procedure is and how well it works.

Read the NICE guidelines on totally endoscopic robotically assisted coronary artery bypass grafting.