Definition and Overview

A coronary artery bypass graft surgery (CABG) is a procedure that involves bypassing blocked or narrow arteries of the heart using a healthy grafted vein or artery from other body parts to improve blood flow.

CABG, which is also referred to as heart bypass surgery, is for patients with coronary heart disease (CHD), a condition characterised by the buildup of plaque or fatty substance in the arteries. When fatty deposits harden, they can cause the artery to rupture and blood clots to form. When this happens, the heart tissues become deprived of oxygen so they eventually become necrotic and die. This then leads to myocardial infarction or a heart attack.

In general, bypass surgery is not always the first treatment option for people with CHD primarily because it is linked to serious risks and complications that can endanger the patient’s life. For conditions that are not life-threatening, the cardiologist typically suggests a combination of complete lifestyle change and medications.

Who Should Undergo and Expected Results

A coronary bypass surgery is considered when:

  • A patient's condition cannot be treated by angioplasty and/or stenting. Also called percutaneous coronary intervention (PCI), angioplasty is a minimally invasive procedure that involves opening the narrowed artery with an inflated balloon and a stent inserted through a catheter.

  • More than one of the coronary arteries are blocked

  • The heart is already weak due to several blockages

  • The blockage is on the left coronary artery

CABG may have significant risks, but in some cases, the benefits can outweigh them. Most of the patients who undergo the surgical procedure (so far, 10% of patients with CHD are treated with CABG) will live for at least ten years with no or very little symptoms related to the condition. It can also boost the quality of life and allow the patient to control other factors that increase CHD risks like enjoying a more active lifestyle.

How Does the Procedure Work?

Bypass operation involves rerouting blood from the blocked or narrowed artery to the grafted one. The graft material may be derived from the chest (internal mammary artery), leg (saphenous vein), or wrist (radial artery). The number of grafts to be used depends on a number of factors like the severity of the condition and the number of arteries blocked.

The heart bypass procedure can be performed using either invasive or minimally invasive methods. CABG surgery is primarily an invasive procedure, which means the heart surgeon is going to create a very large incision to open the chest and access the heart while the patient is under general anesthesia.

The surgeon can then use a heart-lung bypass machine, which circulates the blood throughout the body while the heart’s function is stopped during the surgery.

A more recent variation of the procedure is called the off-pump CABG where no bypass machine is used and the patient is surgically treated while the heart is actively beating.

Both of these procedures may be performed when more than one artery is stenotic or blocked. If there’s only one artery and it’s found in front of the heart, a minimally invasive procedure is performed. This entails making very small incisions around the thoracic area where small surgical instruments are used to operate.

The incisions are closed using wires so the bones in the chest are reinforced. The body heals along with the wires, which stay in the body forever.

The cardiac bypass surgery itself may take as long as 6 hours to complete, but the healing process may require at least three months.

Possible Risks and Complications

One of the possible risks and complications of CABG surgery is death, which occurs in roughly 3% of all the patients. It can be instantaneous, which means the patient dies during or immediately after surgery, or later, in which the patient dies a few days or weeks after the procedure typically due to a heart attack. Other patients, on the other hand, die from or suffer long-term morbidity due to stroke.

Other potential problems include:

  • Allergic reactions to anesthesia

  • Wound infection

  • Weakening of the cardiac muscles

  • Chest pain

  • Inflammation of the heart muscles and/or the lungs

  • Injury to the pericardium of the heart

  • Renal or kidney failure

  • Memory loss or cognitive problems

CABG, also referred to as triple bypass surgery, also doesn’t guarantee that stenosis will no longer recur in the future. Thus, surgeons and cardiologists work on helping patients improve their risk factors way after they have recovered from the procedure.


  • Gopaldas RR, Chu D, Bakaeen FD. Acquired heart disease: coronary insufficiency. In: Townsend CM, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 60.

  • Greenhalgh J, Hockenhull J, Rao N, Dundar Y, Dickson RC, Bagust A. Drug-eluting stents versus bare metal stents for angina or acute coronary syndromes. Cochrane Database Syst Rev. 2010;(5):CD004587. PMID: 20464732.

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