Coronary Artery Bypass Grafting (CABG): Definition & Indications

Instructor: Terri Whisenhunt

Terri has taught in nursing programs and has a master's degree in nursing education.

In this lesson, we will define what a coronary artery bypass grafting (CABG) operation is and why it is done. We will also briefly touch on the risk factors.

Plaque and Coronary Artery Bypass Grafting

Meet Edgar. He's a male in his mid-60s with a history of not exercising, eating a lot of fatty food, being diagnosed with high cholesterol, carrying around 50 extra pounds (mainly in his midsection), and generally just not taking care of himself. He has been having chest pains off and on when doing things like mowing the yard or playing too hard with the grandkids, but it always went away if he would sit down, rest and take his medicine. For the past month though, just sitting down and resting and taking his medication has not been working as well.

When Edgar told his heart doctor this, the doctor scheduled a procedure to examine the three main vessels sitting on the outside of the heart that provide blood to the heart muscle - one to the front, one to the back, and one around the side. These vessels, called the coronary arteries all start on the aorta, which is the main vessel supplying blood to the body from the heart. If any one of these vessels or the branches off these vessels becomes totally blocked, this will cause a heart attack because the heart muscle is not getting the oxygen and food that it needs to live.

Upon finishing the procedure, the doctor explained that over time, a substance called plaque (made of fat, cholesterol, calcium and blood clotting substances) had deposited in the vessel walls and started to narrow the opening of the blood vessel. This narrowing restricted the blood flow to the heart muscle in two different vessels and is what had been causing Edgar's pain. Unfortunately, the narrowing was so severe in a couple of places that it would not be safe to open those areas in a non-invasive procedure, and Edgar would have to undergo a surgery called Coronary Artery Bypass Grafting , also referred to as CABG, in order to get blood flow into those areas that were not receiving enough blood due to the narrowing.

Image showing an open vessel and a partially blocked vessel.

Why Surgery?

The doctor explained there are 3 main reasons why patients undergo a CABG:

  • A coronary artery is completely blocked
  • A coronary artery is blocked in a spot that is not advisable to put a balloon into (like the common spot where the 2 left vessels originate off the aorta or right at the opening of a new branch)
  • There are multiple vessels that have significant spots that are mostly blocked

CABG Description

The term CABG can also refer to the graft placed in surgery itself (Coronary Artery Bypass Graft), and medical personnel tend to use the terms interchangeably. The term bypass is also used interchangeably with CABG to define the graft or the surgery. Depending on how many vessels are unable to adequately deliver blood to the heart due to blockage, a person can undergo single, double, triple or quadruple bypass (more bypasses can be used but is rare). The picture below shows examples of these different types of bypasses.

Image showing single, double, triple and quadruple bypasses.

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