Coronary Artery Bypass Graft Surgery (CABG) Definition

It may sound funny to be told you need "cabbage" surgery. But cabbage is really just the phonetic pronunciation of the abbreviation CABG- well as close as we can get, anyway.

CABG stands for coronary artery bypass grafting, so despite the 'funny' name, it's no laughing matter. The term is quite descriptive of the actual procedure, but to many people it just sounds like a bunch of big medical words all strung together.

In the United States, up to half a million CABG operations may be done per year. The surgery is performed by cardiothoracic surgeons on patients who have significant blockages in the arteries around the heart. These patients usually, but not always, have symptoms of chest pain, especially during exercise and other signs that the arteries are blocked. They may have had medical or stent treatment of their blockages that are no longer working, or the blockages may be not amenable to that type of intervention.

So, what is this CABG surgery?

In short, CABG surgery is a way of rerouting blood around blocked blood vessels that supply the heart with blood and oxygen.

To understand what is achieved during a CABG, let's look at each part of the term, one at a time.

CA is for Coronary Artery

Each organ in the body receives a blood supply that reaches it through arteries. Arteries are the blood vessels that take blood away from the heart and out to the organs.

The heart itself must also be supplied with blood in order to receive the oxygen it needs to function.

The arteries that supply the heart are called CORONARY ARTERIES. The coronary arteries are branches of the aorta- the large main artery that leaves the heart. The coronary arteries branch off from the aorta almost as soon as it leaves the heart and turn back to wrap around the heart, ensuring a supply of blood and oxygen to the heart muscle.

B stands for Bypass

The B in the acronym means "bypass". While the heart-lung bypass machine is used most of the time during these operations, the bypass here actually refers to the fact that the blockages in the coronary arteries are "bypassed" or routed around with new pathways for the blood.

G means Grafting

Graft means to incorporate or join tissue from elsewhere to a site. To re-route the blood around the blockages, new blood vessels are sewn into the coronary arteries that are blocked. This new blood vessel is usually a vein that is "harvested" from the patient's own lower leg. A chest wall artery may also be used, but only in certain situations.

One end of the graft vessel is sewn to the aorta. This is where the blood comes from to supply the coronary arteries (and now the grafted vessel), and the other end is sewn to the coronary artery past the site of the blockage.

CABG surgeries are done under general anesthesia. After a patient is unconscious, a breathing tube and special monitors and intravenous lines are placed.

After sterilizing the surgical sites, a team of surgeons or assistants will harvest the vein from the leg. Either at the same time if enough surgeons are working, or subsequently, the chest and heart are prepared. The incision down the middle of the chest is followed by incision (sawing) of the breastbone (sternum) so that the heart can be reached in the chest cavity.

Heart-Lung Bypass

Most of the time, the operation is performed with "cardiopulmonary bypass", commonly known as the heart-lung machine or bypass machine. It is possible in select patients to do the surgery without bypass (on a beating heart) in an operation called an OPCAB (off-pump coronary artery bypass). But if bypass is used, special tubes are connected from the heart to the bypass machine and back to the body. The large artery leading from the heart, the aorta is clamped off and the heart is protected with special cold fluid (cardioplegia) running through it.

The cardiopulmonary bypass (CPB) machine, run by a specially and highly trained technician, has a special membrane to add oxygen to the blood so that oxygen-rich blood can then be pumped back to the body. The heart is not beating while the CPB machine is working, but blood and oxygen are still delivered to the patient via this special pump. At the end of the surgery, the heart resumes beating and the machine and its tubes are removed.

Other Terminology Related to Coronary Artery Surgery

A "double bypass" means that two grafts were placed, "triple bypass" equals three and so on.

CABG: Coronary artery bypass grafting

OPCAB: Off-pump coronary artery bypass (essentially the operation is performed on the beating heart instead of using the CPB machine).

MICAB: Minimally invasive coronary bypass- surgery done through smaller (3-5 inch) incisions instead of the traditional 10+ inch incisions. Technically, more difficult, but potentially easier recovery.