What Is Off-Pump Coronary Artery Bypass Surgery

  • Sadiatut Taiyebah Bachelor of Science – BSc Biomedical Sciences with Industrial Experience, University of Manchester, England

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What is off-pump coronary artery bypass surgery?

Off-pump coronary Artery Bypass Surgery (OPCAB) is a surgical procedure used to restore blood flow to the heart muscle by creating new routes for blood circulation around blocked or narrowed coronary arteries.1 Traditional coronary artery bypass surgery, also known as On-Pump Coronary Artery Bypass Grafting (CABG), uses a heart-lung machine that temporarily performs the functions of the heart and lungs during surgery.1 While CABG is the standard approach for coronary artery bypass surgery, advancements in cardiac surgery and research have led to the development of off-pump techniques like OPCAB which offers unique advantages.1

The basics of coronary artery disease (CAD)

Coronary arteries are crucial blood vessels that deliver oxygen and nutrients to the heart muscle, allowing it to function properly.2 In the heart, the coronary arteries make up a network that ensures continuous blood flow to the heart for normal cardiac function.2 The coronary arteries guarantee that blood reaches every area of the heart. Our bodies have two major coronary arteries.

  • The left main coronary artery supplies blood to the left side of our heart.2
    •  The left ventricle and the left atrium
  • The right main coronary artery supplies blood to the right side of our heart as well as the nodes of the heart, which control the heart’s rhythm.2
    • The right ventricle and right atrium
    • Sinoatrial and atrioventricular nodes
  • Both coronary arteries branch off to supply the middle (septum) of the heart with blood.2

Coronary Artery Disease (CAD) develops when plaque buildup obstructs or blocks the coronary arteries.3 Plaque is a mixture of cholesterol, fat, calcium, and other substances. As plaque accumulates along the inner walls of the arteries, they becomes narrower or partially/completely blocked.3 This can decrease how much blood reaches the heart muscle. 

Atherosclerosis is the formation of blockages or obstructions inside the coronary arteries caused by the deposit of plaque within the arterial wall lining.3 As a result, the heart may receive less oxygen and nutrients, resulting in a variety of symptoms such as:3

  • Chest pain (angina)
  • Shortness of breath
  • Bodily pain
  • Feeling faint
  • Feeling nauseous

Lifestyle changes and medications can be used to manage the symptoms of mild CAD, such as adopting a healthy, balanced diet, being physically active, and quitting smoking.3 If this is not enough, coronary artery bypass surgery may be advised when the coronary arteries become severely obstructed or blocked.

Understanding traditional coronary artery bypass surgery

Traditional coronary artery bypass surgery, often referred to as on-pump CABG (Coronary Artery Bypass Grafting), is a surgical procedure that deals with coronary artery blockages.4 A surgeon begins an on-pump CABG by making an incision in the chest to access the heart. Once the heart has been accessed safely, its function is temporarily stopped to allow the surgeon to graft a healthy blood vessel harvested from another part of the body onto the blocked/obstructed coronary artery.4 This creates a ‘bypass’ which allows the blood to flow around the blockage, restoring proper circulation to the heart muscle. 

The heart-lung machine takes over pumping and oxygenating blood while the heart has been temporarily stopped.4 This machine diverts blood away from the heart and enriches it with oxygen. The oxygenated blood is then pumped back into the body to ensure that the rest of the body receives oxygen and nutrients while the surgical team operates on the heart, grafts new blood vessels, and repairs the coronary arteries.4

There are some drawbacks and complications associated with on-pump CABG such as:

  • Irregular heartbeat5– Some patients who undergo this procedure may develop an irregular and elevated heartbeat, also known as atrial fibrillation. This is usually corrected with medicine.
  • Infection5 – Wounds in the chest may become infected after surgery and could affect the lungs or inside the chest. This can usually be treated successfully with antibiotics.
  • Kidney complications5 – Some patients may have reduced kidney function post-surgery. The kidneys usually recover and work normally but in more severe cases, kidney dialysis may be required until the kidneys can function normally.

Some factors may increase the chance of developing complications after coronary artery bypass surgery. These include:

  • Age5 – The risk of complications increases with age.
  • Other health conditions5 – A patient with other serious health conditions, such as diabetes or chronic kidney disease, is at higher risk of developing complications.
  • Number of grafts required5 – Needing 3 or more vessels grafted increases the complexity of the operation and puts the patient at greater risk of complications.
  • Obesity5 – If the patient is obese, this complicates the surgery as the surgeon will need to make a deeper incision down the middle of the chest to access the heart, which carries a higher risk of becoming infected.

Off-pump coronary artery bypass (OPCAB) overview

The key difference between on-pump CABG and OPCAB is the use of the heart-lung machine during surgery. As mentioned above, in on-pump CABG a heart-lung machine is used to oxygenate blood and pump blood around the body, while the heart is temporarily stopped to be operated on. In OPCAB, blood vessel grafting is attached to the beating heart, eliminating the need for a heart-lung machine as the heart does not need to be stopped.6

The goal of OPCAB is to improve the blood flow to the heart, manage the symptoms of CAD, and lengthen and improve the quality of the patient’s life.6 To perform an OPCAB, the patient will be put under anaesthetic. A surgeon will then make a long incision down the middle of the chest (sternum) and separate the ribs apart to access the heart.7 Another surgeon will remove a blood vessel from somewhere else in the body, typically the arm or the leg; this vessel will be grafted onto the heart.7 The surgeons will then graft one end of the harvested vessel onto the aorta which is the main vessel that supplies blood to the body. The other end of the vessel is grafted onto the blocked coronary artery to effectively ‘bypass’ the blockage.7 Once this has been completed, the sternum will be wired back together, and the incision will be closed with stitches.6

After an OPCAB, the patient must be monitored in the hospital for several days. The patient’s heart rate and blood pressure will be monitored, and they may have a tube inserted in their throat to help with breathing.7 A chest tube may be attached to drain excess fluid from the chest. At home, the patient will need to rest for several weeks to fully recover. They will be told not to drive until it is safe to do so, to avoid lifting heavy and to follow post-operative instructions regarding medicine, exercise, diet, and wound care.7

There are many advantages of OPCAB:8

  • Less invasive than traditional CABG
  • Surgery takes less time to perform than traditional CABG
  • Can reduce the chance of bleeding during surgery
  • It may reduce the risk of serious complications following surgery
  • Hospital length of stay will usually be shorter

However, as with all methods, there are some associated drawbacks:8

  • Technically demanding procedure due to the nature of the surgery
  • May be too difficult to perform if many blood vessels need to be grafted
  • Surgeons need to undergo specialist training to perform OPCABs

There are also some possible risks associated with the procedure such as:7

  • Infection
  • Blood clots
  • Kidney failure
  • Complications from anaesthesia

The eligibility for OPCAB is determined by many factors that consider the patient's health and the characteristics of their CAD. The patient’s age, medical history, overall cardiac health, and any other pre-existing health conditions will be used to inform treatment decisions. Healthcare providers will also consider factors such as the number of vessels that need to be grafted and the location of the coronary artery blockages.


To summarise, Off-Pump Coronary Artery Bypass Surgery (OPCAB) is a surgical procedure that is used to restore blood flow to the heart muscle by creating new passages for blood circulation around blocked or narrowed coronary arteries. It differs from traditional on-pump CABG as it does not involve the use of a heart-lung machine. OPCAB/CABG are needed when the coronary arteries, which supply the heart muscle with blood, become blocked or obstructed. This is caused by the buildup of plaque in the walls of the arteries which decreases the flow of blood to the heart and can lead to coronary artery disease. The heart requires a constant supply of blood to function normally, so it is important to ensure that all parts of the heart receive blood to get the oxygen and nutrients that are required for proper cardiac function.

OPCAB is performed on patients to restore proper blood flow to the heart. This procedure usually involves a team of cardiothoracic surgeons that will graft new vessels onto the heart while it is still beating, to restore proper circulation to the heart muscle. The risk of complications from this surgery increases with certain factors, such as pre-existing health conditions, age, and obesity. Advantages include a shorter duration in the hospital, as well as being less invasive than traditional CABG.


  1. Lawton JS. Off-pump coronary artery bypass grafting. Mo Med [Internet]. 2012 [cited 2023 Dec 1];109(4):277–80. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6179773/
  2. Anatomy and function of the coronary arteries [Internet]. 2020 [cited 2023 Dec 1]. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/anatomy-and-function-of-the-coronary-arteries
  3. nhs.uk [Internet]. 2018 [cited 2023 Dec 1]. Coronary heart disease. Available from: https://www.nhs.uk/conditions/coronary-heart-disease/
  4. nhs.uk [Internet]. 2017 [cited 2023 Dec 1]. Coronary artery bypass graft (Cabg). Available from: https://www.nhs.uk/conditions/coronary-artery-bypass-graft-cabg/
  5. nhs.uk [Internet]. 2017 [cited 2023 Dec 1]. Coronary artery bypass graft (Cabg). Available from: https://www.nhs.uk/conditions/coronary-artery-bypass-graft-cabg/risks/
  6. Cedars-Sinai [Internet]. [cited 2023 Dec 1]. Articles. Available from: https://www.cedars-sinai.org/health-library/articles.html
  7. Off-pump coronary artery bypass surgery [Internet]. 2019 [cited 2023 Dec 1]. Available from: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/offpump-coronary-artery-bypass-surgery
  8. Livesay JJ. The benefits of off-pump coronary bypass. Tex Heart Inst J [Internet]. 2003 [cited 2023 Dec 1];30(4):258–60. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC307709/

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Sadiatut Taiyebah

Bachelor of Science – BSc Biomedical Sciences with Industrial Experience, University of Manchester, England

Hi! My name is Sadia, and I am a Clinical Trials Administrator at the NHS, focusing on vaccine research and clinical trials management. My academic background led me to develop a keen interest in molecular biology and oncology during my university years. I also gained valuable experience during an industrial year, contributing to the development of cancer diagnostic products. In addition to my healthcare role, I have several years of experience as a tutor in Mathematics and English. I am deeply committed to sharing my knowledge and contributing to the educational growth of others.

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