An Introduction to Coronary Artery Bypass Grafting

An Introduction to Coronary Artery Bypass Grafting

Coronary Artery Bypass Grafting or CABG is one of the most commonly performed surgeries across the world. It is often advised to people suffering from ischemic heart disease.

What are coronary arteries? How does the heart get the blood it needs?

The heart is a complex muscular pump which ensures adequate blood supply to the body. The blood, carrying oxygen and nutrients, is supplied via arteries to various parts of the body. The heart itself needs blood, which is supplied via the coronary arteries, a term used to define the arteries of the heart. These include left and right coronary arteries and their branches. 

The left main coronary artery (LMCA) is short and divides into two branches, the left anterior descending artery (LAD) and the circumflex artery (LCx). These, along with the right coronary (RCA) artery, account for the three arteries referred to in the term ‘triple vessel disease’. These three arteries divide into different branches and supply blood to the muscle of the heart.

What is coronary artery disease? How does it affect the heart?

Coronary arteries may be affected by occlusive atherosclerosis disease. 

Fatty substances get deposited on the wall of the arteries leading to their narrowing. One or more of these coronary arteries may then get blocked decreasing the blood supply to regions of the heart. This causes chest pain or Angina. 

A heart attack may occur in more severe cases, which damages the heart permanently decreasing its efficiency.

CABG (Coronary Bypass Surgery)

CABG is the shortened, more popular name for Coronary Artery Bypass Grafting. This surgery aims to supply the starved heart muscle with more blood by passing through the blockages. The blood vessels from the patient’s own body, which he can spare, are used to perform these bypasses. The internal mammary arteries supply blood to the chest wall and the breast bone. 

The left internal mammary artery commonly known as the LIMA is used to bypass the LAD, which is the most important artery of the heart. The best results have been observed with use of this artery, which increases the survival of the patient by 10-15 years. The veins from the legs called the saphenous veins and the radial artery from the arm are also used. The surgeon studies the coronary arteries and tailors his plan of revascularization to suit the needs of the individual patient. Once the surgeon joins up or anastamoses the grafts, blood flows through them into the blocked arteries beyond the blocks thus bypassing them. The blocks are not removed but are bypassed, hence the name bypass surgery!

Conventional CABG

Coronary artery bypass grafting is the surgical procedure in which the grafts are connected up to the blocked arteries. Conventional CABG is when cardiopulmonary bypass with the heart-lung machine is used to perform the operation. The heart-lung machine allows the heart’s beating to be stopped, so the surgeon can operate on a surface, which is blood-free and still. The heart-lung machine maintains life despite the lack of a heartbeat, removing carbon dioxide from the blood and replacing it with oxygen before pumping it around the body.

Beating Heart Bypssssass Surgery (Off-pump Surgery)

Off-pump or beating heart bypass surgery allows surgeons to perform surgery on the heart while it is still beating. A medication may be given to slow the heart during surgery, but the heart keeps beating during the procedure. This type of surgery may be an option for patients with single-vessel disease.

During off-pump or beating heart surgery, the heart-lung machine is not used. The surgeon uses advanced operating equipment to stabilize portions of the heart and bypass the blocked artery in a highly controlled operative environment. Meanwhile, the rest of the heart keeps pumping and circulating blood to the body.

Inputs by Dr. Sanjeev Jadhav, Consultant Cardio-Vascular & Thoracic, Heart & Lung Transplant Surgeon at Apollo Hospitals, Navi Mumbai.