Coronary artery bypass graft surgery | Pokanga ia manawa

Commonly known as 'bypass surgery'

A coronary artery bypass graft (CABG or pokanga ia manawa) is a surgical procedure used to treat coronary artery disease. It involves rerouting blood around narrowed or clogged parts of your heart's major arteries to improve blood flow and oxygen supply to your heart muscle.

Key points

  1. Bypass surgery is normally done to relieve symptoms of angina (chest pain) and reduce the risk of heart attack caused by coronary artery disease.
  2. Coronary artery disease is when the arteries leading to your heart muscle become narrowed and hardened due to the build-up of fatty deposits called plaques.
  3. Bypass surgery involves removing a blood vessel from some other part of your body and using it to create a detour or bypass around the clogged artery leading to your heart muscle. This allows blood to reach your heart muscle again.
  4. The new blood vessel is known as a graft. Sometimes a number of grafts may be needed.
  5. Bypass surgery is not a cure for heart disease. By improving blood flow to the heart muscle, bypass surgery can help control your symptoms and reduce the requirement for angina medicines. However, it does not fix the underlying heart disease that caused the symptoms in the first place.
  6. To lower your chance of further heart problems, you will need to make and maintain changes to your lifestyle and take medications for life.

Why do I need coronary artery bypass surgery?

Your heart, like all organs, needs a constant supply of blood to provide it with oxygen and nutrients. Two arteries, called the left and right coronary arteries, supply the blood.

Over time, arteries can narrow and harden due to the build-up of fatty deposits called plaques. This process is known as atherosclerosis. When this happens to your coronary arteries, it is known as coronary artery disease.

You are more likely to develop coronary artery disease if you:

  • smoke
  • are overweight or obese
  • eat a high-fat diet.

Coronary artery disease can cause angina. This is chest pain caused by reduced blood flow. Mild angina can be treated with medicine but bypass surgery may be needed to help improve blood flow if you have severe angina.

If you have coronary artery disease you also have a higher risk of heart attack. A heart attack can be triggered when one of the plaques splits, creating a blood clot, which can block the blood supply to your heart.

If you are high risk for a heart attack a coronary bypass operation may be recommended.

What happens during coronary bypass graft surgery? 

Coronary bypass surgery involves removing a blood vessel from another part of your body (usually your chest, arms or legs) and attaching or grafting it to the coronary artery above and below the narrowed area. This creates a detour or bypass around the blocked artery leading to your heart.

The new blood vessel is known as a graft. It is quite normal to need two, three or four grafts, otherwise known as a double, triple or quadruple bypass, although more can be done.

The procedure

A coronary bypass is carried out under general anaesthetic, which means you’ll be in a sleep-like state during the operation. It normally takes between 3 and 6 hours.

The surgeon will make a cut (incision) of about 25 cm long down the middle of your chest, through the breastbone (sternum) to reach your heart. While your heart is being operated on, it is usual for it to be temporarily stopped. During this time, the flow of blood to your heart and lungs is rerouted through a heart-lung bypass machine. The machine takes over your heart’s job of pumping and your lungs’ job of breathing.

Alternatively, some surgeons perform off-pump bypass surgery, where they operate without using the bypass machine.


After the operation, you will be closely monitored in the Intensive Care Unit (ICU) for between 12 and 24 hours. You may feel a little disorientated and will be quite sleepy.

Once back on the ward, your progress will be monitored. You will probably be a bit sore after the operation and will need to have pain relief, which the nurses will arrange.

Your medicines, such as those you take for angina, may be changed as your body recovers.

You will need to stay in hospital for about 5 to 7 days after having a coronary artery bypass graft.

Recovery takes time and everyone recovers at slightly different speeds. Generally, you should be able to sit in a chair after 1 day, walk after 3 days, and walk up and down stairs after 5 or 6 days.

When you are discharged, you will need someone to look after you at home for between 10 and 14 days. You must not go home alone.

Most people make a full recovery within 12 weeks. 

Preparing for your operation

Before your surgery, you will need to have a few routine investigations, including:

  • an ECG (electrocardiogram)
  • a chest x-ray
  • blood tests.

You will also need to look at lifestyle issues such as:

  • quitting smoking if you are a smoker
  • organising leave
  • travel and accommodation
  • support during and after surgery
  • adopting a heart healthy lifestyle
  • preparing yourself emotionally.

You should discuss any questions and concerns with your doctor or nurse beforehand. Some of these issues are discussed below.

Why do I need to quit smoking?

If you smoke, it is strongly advised that you quit. Quitline ph 0800 778 778 can help with support. Surgeons and anaesthetists are very reluctant to work on people who continue to smoke, because of breathing complications after surgery and the increased risk of blocking the new grafts. 

How long will I need to take off work?

Inform your employer that you are having surgery and arrange sick leave. The recovery period after surgery is about 8 to 12 weeks. You may feel well enough to return to work 6 weeks after the operation. If you drive a vehicle that requires a special licence there is a stand-down period of 3 months and you will need clearance before resuming driving

What if I need to travel for my surgery?

If you need to be transferred to another centre for surgery, the referring hospital normally meets the cost of your travelling expenses. Your specialist will be able to advise you who to contact to arrange this.

Cardiac surgical units try to help with accommodation and other social, emotional or practical problems that may arise when you have major surgery away from your home town. If you need help, contact the social work department of the hospital concerned.

Why is a heart-healthy lifestyle so important?

Heart bypass surgery helps improve symptoms caused by heart disease, but it is not a cure for heart disease. The best way to prevent further damage is by reducing or removing any risk factors.

Even a small change can have a positive impact on your risk of heart attack and stroke. The more you change, the better for your health. 

Learn more about: 

What is cardiac rehabilitation?

Undertaking a cardiac rehabilitation programme will provide you with information and support on how to tackle your risk factors and lead a healthy lifestyle.

Cardiac rehabilitation programmes offer you and your family information and support on a variety of cardiac-related subjects and support you in your recovery. Programmes are available in most centres. Contact nursing staff prior to discharge, your doctor or the Heart Foundation branch in your area. 

Learn more                

Coronary artery bypass surgery Heart Foundation of NZ
Coronary arteries – explained Interactive Cardiovascular Library – American Heart Association
Coronary bypass surgery – explained Interactive Cardiovascular Library – American Heart Association

Credits: Health Navigator Editorial Team . Reviewed By: Dr Andrew McLachlan, CMDHB Last reviewed: 06 Jun 2019