Cardiac Surgery

Heart surgery including coronary bypass (CABG), valve replacement or repair, and other open-heart procedures.

Duration: 4–6 hours Hospital stay: 5–7 days Recovery: 6–12 weeks

Types of cardiac surgery

Common cardiac operations include:

  • Coronary artery bypass grafting (CABG) — creates a detour around a narrowed or blocked heart artery, using a blood vessel taken from your leg, arm, or chest. Some people need more than one bypass (a "double" or "triple" bypass).
  • Valve repair or replacement — repairs or replaces a heart valve that has become narrowed or leaky. Replacement valves are either mechanical (very durable, but need lifelong blood-thinning medication) or tissue (usually no long-term blood thinners, but may not last as long). Your surgeon will discuss which suits you.
  • Surgery for irregular heart rhythms — such as a MAZE procedure to treat atrial fibrillation, or closing off the left atrial appendage to lower your risk of stroke. Often done at the same time as a CABG or valve operation.

Most heart surgery is done through a full incision down the centre of the chest (a sternotomy), using a heart-lung bypass machine (see both below). Some operations can be done through smaller incisions, or without stopping the heart at all; your surgeon will tell you if either applies to you.

The chest incision (sternotomy)

To reach your heart, the surgeon makes a cut down the centre of your chest and divides the breastbone (sternum). At the end of the operation the sternum is wired back together; these wires are permanent and do not need to be removed. While the bone heals, you will be asked to follow sternal precautions: avoiding heavy lifting, pushing, and pulling.

A smaller number of operations (particularly some mitral valve operations) can be done through smaller incisions between the ribs instead (minimally invasive cardiac surgery), if your anatomy and your surgeon's assessment make this suitable.

The heart-lung bypass machine

During most heart surgery, a heart-lung bypass machine temporarily does the work of your heart and lungs, adding oxygen to your blood and circulating it around your body. This lets the surgeon operate on a still, resting heart. Once the surgery is finished, the machine is switched off and your heart takes over again.

Some operations, particularly some bypass surgeries, can be done "off-pump" (on a beating heart, without the bypass machine). This is not common, and whether it suits you depends on your anatomy and your surgeon's assessment.

Your Journey

  1. Before surgery

    Use the weeks before surgery to get as fit as you can (see the Prehabilitation section below). The fitter you go in, the smoother your recovery tends to be.

    Your teeth may be checked before surgery, as dental infections can be serious after heart surgery.

    Getting Ready for Hospital (PDF)

  2. The day of surgery

    You'll usually be admitted the day before your operation. Your surgeon will confirm consent and the surgical plan, your anaesthetist will discuss your anaesthetic and pain relief, and your nurse will run through a checklist, do an ECG, and prepare your skin (this may include shaving your chest and parts of your arms or legs).

    Heart surgery is done under general anaesthesia and usually takes 4 to 6 hours. Once you are under anaesthesia, your anaesthetist places extra monitoring: a fine line in your wrist (an arterial line) for continuous blood pressure monitoring and blood samples, and a line in your neck (a central line) for fluids and medicines. These let the team watch you as closely as possible throughout the operation. Some patients need a blood transfusion during or after heart surgery; this is monitored closely and only given if you need it.

    We'll keep your whānau updated if the operation runs significantly longer than expected.

    You'll go straight to the Intensive Care Unit (ICU) afterwards, still under anaesthetic. The ICU team will make sure your condition is stable, then stop the medications that are keeping you under anaesthesia, allowing you to wake up in your own time. It's bright and busy, with lights on day and night, so it's common to feel unsure about time at first. You'll wake with several tubes and lines in place, all there to help us look after you, and all removed as soon as you no longer need them:

    • a breathing tube, removed once you're awake and breathing on your own
    • the arterial and central lines placed during your operation
    • ECG leads monitoring your heart rhythm
    • a urinary catheter
    • one or more chest drains
    • fine pacing wires (a backup for your heart rhythm; you won't feel them)

    Seeing you in ICU can be confronting for family and whānau, as you'll look different at first surrounded by this equipment.

  3. In hospital

    Most people spend one to two days in ICU before moving to a closely monitored step-down area, then to the ward. Your total stay is usually 5 to 7 days. The team updates you each day on the ward round, and lines and tubes come out gradually as you need them less.

    Pain relief. Good pain control matters. It lets you breathe deeply, cough, and move, which helps prevent chest infections. You'll have regular paracetamol plus stronger relief (a patient-controlled button in ICU at first, moving to tablets once your chest drains are out). Ask for more if you need it.

    Breathing and moving. The bypass machine and a sore chest can make deep breathing harder, raising your risk of a chest infection. Do your breathing exercises (see the Prehabilitation section below), sit up, and get out of bed as soon as you can. A physiotherapist will guide you and check you before you go home.

    Cultural and pastoral support is available throughout your stay, including Whānau Care Services for Māori patients, Pacific health support, and chaplaincy for all faiths and none. Ask staff for a referral.

  4. Going home

    You'll leave with a discharge summary (also sent to your GP), a medication plan, and a booklet covering early recovery, what to watch for, follow-up, and cardiac rehabilitation. Don't restart old medications without checking with your pharmacist or doctor first.

    Sternal precautions. While your breastbone heals (about 6 to 8 weeks), avoid lifting, pushing, or pulling anything heavy, and support your chest with a folded towel or pillow when you cough.

    Driving. No driving for 4 weeks after surgery (an NZTA requirement). Your team will tell you if you need a specialist assessment before returning to the wheel.

    Work. Most people need 6 to 8 weeks off, longer if your job is physically demanding.

    What to expect. Most patients are surprised to find they're less sore than they expected, but far more tired. That's normal; it can take up to 12 weeks to feel back to full strength. You may also notice you have to think harder about things that used to feel automatic. For most people this clears within a few weeks; for a smaller number it can take several months. None of this means something has gone wrong. Talk to your surgeon or anaesthetist about what to expect for you specifically, and ask as many questions as you need to.

    Check your wound daily for redness, swelling, discharge, increasing pain, or fever.

    Cardiac rehabilitation. An outpatient programme is an important part of your recovery, and most people find it genuinely useful.

    Get urgent help (your nearest emergency department, or call 111) for chest pain, a fast or irregular heartbeat, severe or worsening breathlessness, or fainting. Contact your GP or surgical team for a fever, wound redness or oozing, or pain your medication isn't controlling.

    Looking after your heart, long term.

    • Maintain a healthy weight and eat well: more vegetables, fruit, whole grains, and lean protein; less processed food, salt, and saturated fat.
    • Keep cholesterol and blood pressure checked and treated. Both quietly damage arteries over time, often with no symptoms.
    • If you have diabetes or pre-diabetes, keep your blood sugar in range with your GP.

    See the Heart Foundation for more information, or self-refer for a Green Prescription (subsidised exercise support).

Prehabilitation

Research shows that patients who are fitter before surgery recover faster, have fewer complications, and spend less time in hospital.

Prehabilitation has six main parts:

  • Stop smoking and vaping
  • Breathing exercises (before and, more importantly, after surgery)
  • Reduce alcohol intake
  • Aerobic exercise
  • Strength training
  • Mental readiness

Aim to start at least 4–8 weeks before your operation if you can.

Stop smoking and vaping

This is one of the most important things you can do before surgery. You could lower your risk of a complication by up to 40%. Smoking reduces the oxygen reaching your heart and other vital organs, raises your risk of breathing complications, and slows wound healing. Longer term, it increases your risk of heart disease, lung disease and cancer.

Aim to stop at least 8 weeks beforehand. Even 24 hours helps. If you are ready to quit smoking, Quitline can support you with a plan designed to help you, all for free.

Breathing exercises

Why this matters

Every day, you breathe in bacteria and particles from the air around you. Your lungs clear these continuously using a layer of mucus and millions of tiny hair-like structures called cilia, which work like a moving belt, sweeping debris upward to be coughed out or swallowed.

Anaesthetic medicines and prolonged bed rest temporarily impair this system. Without active steps to compensate, bacteria can build up and cause a chest infection (also called pneumonia). Abdominal and chest surgery adds another challenge: your main breathing muscle, the diaphragm, is held back by pain and surgical trauma, making deep breathing feel difficult.

Up to 50% of patients undergoing major abdominal or chest surgery develop a breathing complication (including chest infections and pneumonia) if breathing exercises are not performed. For non-major operations this is up to 30%.

The good news: starting deep breathing exercises as soon as you wake from anaesthesia significantly reduces this risk. Practise before your operation so you know exactly what to do when it counts.

How to do your breathing exercises

Work through the cycle below. Aim to complete 20 deep breaths per session, and do a session every waking hour after surgery. Before your operation, practise 2 to 3 times a day so it becomes natural.

NORMAL BREATHING BREATHE IN SNIFF & PAUSE HOLD BREATHE OUT Big, slow breath in Sniff! Sniff again! Pause Hold 3–5 sec Let it rush out Cough if needed: press a folded pillow firmly to your wound
One breathing cycle: a big slow breath in, two extra sniffs, a short hold, then let the air rush out. Repeat until you reach 20 breaths.
  1. Take a big, slow breath in through your nose, letting your chest and abdomen expand fully.
  2. Pause briefly at the top, then take two short extra sniffs to fully inflate your lungs.
  3. Hold for 3 to 5 seconds.
  4. Let the air rush out freely. If you feel any phlegm, press a folded pillow or both hands firmly against your wound and have a strong cough.
  5. Repeat until you reach 20 breaths per session.

When to do this

After your operation (this is the most important time): every hour while awake.

Before your operation: 2 to 3 sessions each day to build the habit.

Download: Preventing Lung Problems After Surgery (PDF)

Reduce alcohol intake

Cutting down alcohol lowers the risk of bleeding, infections and heart complications.

Stopping harmful drinking before surgery can lower some complications by up to 75%.

Is your drinking OK? Fill in this quick questionnaire to find out. Extra help and support can be found here.

Aerobic exercise

Activity that raises your heart rate and deepens your breathing. Brisk walking is ideal. Aim for 30 minutes each day, split into shorter blocks if needed (for example, three 10-minute walks). Build up gradually.

Strength training

Exercises to maintain muscle mass. Try 60 to 100 sit-to-stands through the day (sets of 10 to 20 using a chair), plus arm curls with a light weight.
Stop if you feel dizzy or unwell.

Always work within your own limits. It is normal to feel slightly tired or mildly sore as your body adapts. If you experience chest pain, severe breathlessness, or dizziness, stop and seek medical advice.

Mental readiness

Feeling prepared and knowing what to expect reduces anxiety and helps you take an active part in your recovery. Read through the educational information your team gives you, and the guides on this website, so there are no surprises along the way. Simple relaxation or breathing techniques, a regular sleep routine, and arranging help at home before you come in all support a calmer, smoother recovery.

Nutrition

Good nutrition in the weeks before your operation helps your body prepare for the physical stress of surgery and supports faster healing afterwards.

  • Eat regular meals with a good source of protein at each one (meat, fish, eggs, dairy, legumes, or tofu).
  • Eat plenty of vegetables and fruit to provide vitamins and minerals that support healing.
  • Stay well hydrated. Aim for 6–8 glasses of water per day. Limit sugary drinks and excessive caffeine.
  • Try to maintain a healthy weight. If you are significantly underweight or have lost weight recently, tell your surgical team. You may benefit from nutritional support before your operation.

Fasting before surgery reduces the risk of complications during anaesthesia.

  1. 6 hours before surgery

    Stop eating solid food. You may continue to drink clear fluids. No milk, smoothies, or fizzy drinks. You can chew gum but make sure to spit it out before going into theatre.

  2. 2 hours before surgery

    Stop all fluids, including water, black tea or coffee, and clear juice.
    Many hospitals now use sip 'til send. This means you can have up to 200ml of water per hour until the time you go through to theatre. Please ask the nurses who call you regarding this.

  3. Some hospitals provide a carbohydrate drink

    Your team may give you a carbohydrate loading drink (such as Preload or similar) to take 2 hours before surgery. This reduces thirst, hunger, and post-operative nausea. Follow your team's specific instructions.

Always follow the specific fasting instructions from your surgical or anaesthetic team. These take priority over the general guide above, particularly if you have diabetes or a condition affecting stomach emptying.

Protein is the building block your body uses to heal wounds, rebuild muscle, and fight infection. In the weeks before surgery, aim to eat more protein than usual.

  • Target: 1.2–1.5 grams of protein per kilogram of body weight per day. (For a 70kg person, that is 85–105g per day.)
  • Good food sources: chicken, fish, eggs, Greek yoghurt, cottage cheese, lentils, chickpeas, tofu, and nuts.
  • Protein supplement drinks (e.g., Fortisip, Ensure, Complan) can be helpful if your appetite is poor or you are struggling to eat enough. These are available from pharmacies without a prescription.

If your surgical team recommends specific nutritional supplements, take these as directed. Tell your team if you are finding it difficult to eat enough. Nutritional support services are available.

Alcohol

Stop drinking alcohol at least 4 weeks before surgery. Alcohol increases bleeding risk, impairs wound healing, suppresses immune function, and affects how your body responds to anaesthesia and pain relief.

Smoking

Stop smoking as early as possible, ideally 8 weeks before surgery. Smoking significantly increases the risk of wound infection, chest complications, blood clots, and slower healing. Your GP can help with cessation support.

Herbal supplements

Stop all herbal and natural supplements at least 2 weeks before surgery. Many affect bleeding or interfere with anaesthetic drugs. This includes: garlic capsules, ginkgo biloba, ginseng, St John's Wort, kava, valerian, and high-dose fish oil.

Grapefruit

Avoid grapefruit and grapefruit juice in the week before surgery. Compounds in grapefruit block a liver enzyme that breaks down many medications, including some used in anaesthesia and pain management.

Anaesthesia

Anaesthesia means using medicines to block pain and keep you comfortable during your operation. There are several types. Your anaesthetist will discuss which is most appropriate for you and your surgery.

General anaesthesia

You are completely unconscious for the operation. Medicine is given through a drip in your arm, and you breathe with the help of an airway device placed once you are under anaesthesia. You wake up in the Post Anaesthesia Care Unit (PACU) when the operation is finished. This is the most common type for major surgery.

General Anaesthesia leaflet (PDF)

Spinal or epidural

An injection into your back numbs the lower half of your body. You stay awake or are given light sedation to keep you comfortable. This is commonly used for hip and knee replacement, some bladder surgery, and some bowel operations. The numbness wears off gradually over a few hours after surgery. Sometimes a spinal or epidural is combined with a general anaesthetic for major chest or abdominal surgery, to provide pain relief after the operation.

Spinal Anaesthesia leaflet (PDF)

Epidural leaflet (PDF)

Nerve block

A targeted injection of local anaesthetic near a specific nerve numbs just one area (for example, your arm, shoulder, or leg). Nerve blocks are often used alongside general anaesthesia to reduce pain after the operation and reduce the need for strong opioid pain relief.

Sedation

You receive medication through a drip to make you relaxed and drowsy. You remain breathing on your own and can still respond. Used for some minor procedures, scopes, and operations under local anaesthetic where a degree of relaxation is helpful.

What to tell your anaesthetist

Before your operation, make sure your surgical and anaesthetic team knows about all of the following:

  • Allergies, especially to medicines, latex, iodine, or any previous reaction to an anaesthetic
  • All supplements, vitamins, herbal products, and over-the-counter medicines, including things you might not think of as medicines
  • Recreational drug use. This is confidential and is essential for safe anaesthetic planning
  • Previous anaesthetic problems, including nausea, awareness, slow waking, or any family history of anaesthetic reactions (particularly malignant hyperthermia)
  • Dental work: loose teeth, crowns, caps, veneers, or a bridge at the front of your mouth

Common questions

Anaesthetic awareness (waking up or having any awareness during a general anaesthetic) is very rare. Overall, it occurs in around 1 in 20,000 cases with modern techniques. The risk can change depending on the type of operation and anaesthesia. Your anaesthetist monitors the depth of your anaesthetic continuously throughout the operation using dedicated monitoring equipment. If you are worried about this, please raise it at your pre-assessment appointment. Your anaesthetist can discuss the precautions used.

Post-operative nausea and vomiting (PONV) is common after surgery but very manageable. Your anaesthetist will give you anti-nausea medication routinely during and after the operation. If you have a strong history of PONV, motion sickness, or have felt very sick after a previous anaesthetic, tell your team at your pre-assessment. They can plan extra precautions, including additional anti-nausea medications and changes to your anaesthetic technique.

Most regular medications should be taken as usual on the morning of surgery with a small sip of water, even if you are fasting. However, some medications (particularly diabetes medications, blood thinners, and certain newer drugs) need specific adjustments. Your surgical and anaesthetic team will give you written instructions. See the Medications section on this page for a detailed guide. If in doubt, contact your pre-assessment clinic or GP.

Feeling anxious before surgery is completely normal. Most patients do. It helps us to look after you better if you talk about your concerns with your anaesthetist at your pre-assessment appointment. Understanding exactly what will happen often helps significantly. If your anxiety is significant, ask your GP or surgical team about additional support options.

A pre-assessment appointment happens before your operation. A specially trained nurse and anaesthetist will review your general health, current medications, and any test results. You may have blood tests, an ECG, or other checks done at this appointment. It is also your opportunity to ask questions about your anaesthetic and what to expect on the day. Completing the pre-assessment questionnaire on this website before your appointment will save time and help your team prepare.

Medications

Getting your medications right before surgery is important for your safety. Use this as a general guide, but always follow the specific written instructions from your surgical or anaesthetic team. These take priority.

Fasting for surgery does not usually mean stopping your regular tablets. Most should still be taken on the morning of surgery with a small sip of water. Bring all your medicines (and any devices such as a CPAP machine) with you on the day.

Usually continue

Keep taking these as normal, including on the morning of surgery with a sip of water, unless your team tells you otherwise:

  • Blood pressure and heart medicines (such as beta-blockers and calcium channel blockers)
  • Heart rhythm medicines
  • Cholesterol medicines (statins)
  • Thyroid medicines
  • Inhalers (asthma, COPD)
  • Acid reflux medicines (omeprazole, pantoprazole, famotidine)
  • Antidepressants, antipsychotics, and lithium
  • Anti-epilepsy (seizure) medicines
  • Parkinson's medicines (it is important not to miss doses)
  • Inhaled and regular steroids (do not stop just because you are fasting)
  • Regular pain medicines, including anti-inflammatories (ibuprofen, diclofenac, naproxen) and opioids
  • Eye drops

Some blood pressure medicines called ACE inhibitors (names ending in "pril") and ARBs (names ending in "sartan") are sometimes withheld on the day of surgery. Follow your team's instructions.

Usually stop (with advice)

These are usually paused before surgery. Do not stop anything without first confirming the timing with your team:

  • Diabetes tablets (metformin, gliclazide): usually stopped on the morning of surgery.
  • SGLT-2 inhibitors (Jardiance/empagliflozin, Forxiga/dapagliflozin): stop 3 days (72 hours) before. They can cause a serious problem (ketoacidosis) around surgery even if your blood sugar looks normal. If you take one for heart failure rather than diabetes, your team may advise continuing.
  • Aspirin taken for general prevention: stop 5 days before. If you take aspirin after a heart attack or stroke, it is usually continued. Check with your team.
  • Appetite suppressants (phentermine/Duromine, Contrave): stop several days before (2 to 7 days, depending on the medicine and your heart health).
  • ADHD stimulants (methylphenidate/Ritalin/Rubifen, dexamfetamine): hold on the day of surgery.
  • Erectile dysfunction tablets (sildenafil/Viagra, tadalafil): stop 2 weeks before. If prescribed for pulmonary hypertension, continue.
  • Cannabis and cannabis products: avoid for at least 12 hours before, and cut down in the week beforehand. Tell your team if it is medically prescribed.

Need an individual plan

These need a plan made just for you. Your team will give you specific written instructions:

  • Insulin and overall diabetes management: doses almost always change around surgery. Wait for your team's plan.
  • Blood thinners (anticoagulants) (warfarin, rivaroxaban/Xarelto, apixaban/Eliquis, dabigatran/Pradaxa): when to stop depends on your surgery and your clot risk, and some people need bridging. Your team will give you a written plan.
  • Antiplatelets (clopidogrel/Plavix, ticagrelor): whether and when to stop depends on why you take them.
  • GLP-1 medicines (Ozempic/semaglutide, Saxenda/liraglutide, Trulicity/dulaglutide): usually continued, but you will be asked to have only clear fluids for at least 24 hours before surgery, because they slow stomach emptying. Follow your team's fasting instructions.
  • Immune-suppressing and biologic medicines (methotrexate, adalimumab/Humira, etanercept/Enbrel, and similar): timing is planned around your dose, with your specialist and anaesthetic team.
  • Long-term steroids: you may need extra ("stress dose") steroids around surgery, which your team will arrange. Do not stop them.
  • Contraceptive pill and menopause hormone therapy (HRT): usually continued with clot-prevention measures. If you have a high clot risk, your team may discuss stopping.

This is a general guide and does not cover every medicine. For combination tablets, or any medicine, supplement, or herbal product not listed here, or if you are at all unsure, ask your pre-assessment clinic, GP, or anaesthetic team. See the Anaesthesia section for what else to tell your anaesthetist.

Pre-Assessment Questionnaire

Complete this at home before your pre-assessment appointment. When you reach the end, you can print your summary or email it directly to your clinic.

Start questionnaire