Heart bypass surgery, or coronary artery bypass graft (CABG) surgery, is done when coronary arteries, which supply your heart with oxygenated blood, become blocked or damaged. If these arteries are blocked or blood flow is restricted, the heart doesn’t work properly. This surgery may be recommended for those with obstructive coronary artery disease (CAD), which means that plaque has built up in the arteries to the point that it is blocking the supply of blood to the heart. This blockage is usually the result of an accumulation of fatty material (composed of cholesterol, calcium, and fibrin) called plaque.

What Is Heart Bypass Surgery?

A heart bypass procedure involves attaching (grafting) a blood vessel taken from elsewhere in the body to the diseased coronary artery. This results in a redirection of the blood flow around the blockage. When a person has a double (or triple) bypass surgery, it means that two or three arterial blockages are rerouted.

Heart bypass surgery is done as an inpatient procedure. It’s often a planned procedure, but in some instances, an emergency heart bypass procedure is performed after a person has a heart attack.1

Heart bypass surgery may sometimes be performed on infants and children, but not for the same reason adults have the procedure done. Rather, infants and children usually have heart bypass surgery because of congenital (present at birth) heart disease.2

The steps involved in a traditional open method of heart bypass surgery include:

1. The anesthesiologist administers medication to induce unconsciousness (put you to sleep) so that your surgery is pain free. 
2. The surgeon will make an incision in the middle of the chest and the breastbone is separated to allow for an opening to perform the surgery.
3. You will be connected to a machine called a cardiopulmonary bypass pump (CPB), sometimes called a heart-lung bypass machine, which takes over the function of the heart—while your heart is stopped—so that the surgeon can perform the procedure. 
4. The surgeon will construct the bypass graft by taking a healthy vein or artery (from a different part of the body) and using it to build the bypass around the blocked coronary artery. Often, the saphenous vein—from the leg—is used to create the bypass. In this instance, an incision is made along the inside of the leg to remove the saphenous vein.
5. The saphenous vein is connected to the blocked artery (below the area where the blockage exists) on one end and then to the aorta (via an opening that is created) at the other end. Blood can now travel through the newly constructed artery, bypassing the blockage. There are other arteries that may be used as grafts in bypass surgery, including the radial artery in the wrist and the internal mammary artery (IMA) in the chest. Note, IMA sourced grafts are said to be superior to vein grafts because they are able to withstand the blood pressure over time. this results in better outcomes, which reduces the incidence of the future need for re-operation.3
6. Depending on how many blocked arteries you have, the surgeon may perform more than one coronary artery bypass procedure during the same surgery.
7. Once the graft has been completed, the breastbone is closed (using wires that stay inside the body). The incision is then sutured. 

The duration of the surgery is about four to six hours. After the procedure, you will be taken to the intensive care unit (ICU) or the coronary intensive care unit (CICU) to recover.

Various Surgery Techniques 

There are several variations of the surgical technique that differ from an open CABG procedure, these include:4

Off-Pump Coronary Artery Bypass (OPCAB)

An off-pump coronary artery bypass does not employ the cardiopulmonary bypass pump (CPB). The operation is done while the heart is beating.

Minimally Invasive Direct Coronary Artery Bypass (MIDCAB)

MIDCAB is a less invasive procedure with a minimal (2.5 inch) opening in which an artery is harvested directly or by utilizing a surgical robot. It is performed while the heart is still beating so the heart-lung bypass machine is not required.

This procedure has several advantage such as a quicker recovery time, fewer side effects, and a decrease in the need for blood transfusions.5

Totally Endoscopic Coronary Artery Bypass (TECAB)

TECAB is performed through four to five fingertip-sized slits with the help of the da Vinci Surgical System. This system enables the surgeon better control and precision than traditional surgical methods.

The robot doesn’t actually perform the surgery, but rather, acts as a tool that the surgeon controls from a nearby console. A very small camera, attached to the robotic arms, provides a three-dimensional view of the operating space inside the thorax (chest). The advantages of robotic surgery include: 3

• Quicker recovery times
• Much smaller incisions (without the need to split the breastbone open)
• Quicker pain resolution and minimal blood loss
• Ideal for elderly people with weakened bones (due to osteoporosis) because the breastbone does not have to be cut, which would require re-growth and healing after surgery.
• The heart continues beating during the surgery, so the heart-lung bypass machine is not required.
• Most often, internal mammary artery grafts are used; grafts from other parts of the body, which may not be as strong in withstanding the blood pressure, are infrequently used.3

Hybrid Technique (Bypass plus stenting)

A hybrid bypass procedure is a MIDCAB or TECAB combined with stenting techniques. A hybrid technique may be recommended for those with multiple blockages, or in people who do not qualify to have all blockages repaired via minimally invasive surgery.

The combined procedure involves very small incisions and guide catheters used to insert a stent (a small mesh tube) which helps to enlarge part of the artery to improve blood flow. This approach offers the advantage of having two procedures (the coronary bypass surgery and the stenting technique) in one operation.

Other advantages of the hybrid technique include:

• Reduction in blood loss
• Smaller incisions
• Quicker recovery times
• The long-term benefit of having surgery, plus stenting.6

Each type of procedure has its own complexities, benefits, risks, prerequisites, and contraindications. Be sure to speak to your surgeon about which procedure is right for you.

Contraindications

Contraindications for heart bypass surgery include those whose coronary arteries aren’t compatible with grafting or heart muscle tissue that isn’t viable to graf.7 Even if these don’t apply to you, bypass surgery will only be considered after weighing the risks and benefits in your case.

This is a major procedure. Your prognosis, age, and any comorbidities, among other things, will all factor into your doctor’s recommendation.

Note, although age is not considered a contraindication for having heart bypass surgery, it does pose an increased risk for complications. A 2020 study found that those who were 80 to 89 years old were more likely to develop heart, liver and respiratory complications, and they had a higher mortality (death) rate associated with heart bypass surgery. 8

Benefits

There are many important benefits to having heart bypass surgery, these include:

• A lower risk of future heart attacks
• A symptom free life, without pain (such as angina) for up to 15 years
• Longer survival rates compared to those who had other types of surgery (such as angioplasty, a procedure to open blocked blood vessels). 9

Potential Risks 

There are many series risks associated with heart bypass surgery, these include the risk of:

• Bleeding at the graft site: Nearly 30% of those who received a heart bypass surgery required a blood transfusion after the procedure.10
• Additional surgery: This may be required due to bleeding and other causes.
• Irregular heart rhythm: Atrial fibrillation, a condition in which the heart quivers instead of pumping and does not sufficiently circulate the blood.
• Blood clots: These may form in the heart and travel to other parts of the body. These clots can contribute to the risk of heart attack, stroke or lung problems.
• Infection: This can occur at the surgical site. It is a rare complication that only occurs in 1% of people who undergo heart bypass surgery.10
• Failure of the graft: If this occurs, it may result in a re-operation and/or further treatment.
• Post-pericardiotomy syndrome: A condition that involves symptoms of fever and chest pain; this condition occurs in approximately 30% of those who undergo heart bypass surgery10
• Kidney failure: This can result from the surgery, which can inadvertently damage the kidneys, but this is usually temporary.
• Memory loss: The cause of this complication is unknown, but one theory is that it may be linked to the use of the heart-lung machine, which could dislodge minute particles of fatty build up from an artery to travel to the brain
• Complications of general anesthesia: There is a risk of pneumonia occurring, as with any type of surgical procedure,
• Death: This is rare, but when it occurs in-hospital after the procedure, it is usually caused by a heart attack or a stroke.

There has been a dramatic reduction in the incidence of serious complications associated with a heart bypass surgeries. In fact, in 95% of the cases of heart bypass surgeries, there are no serious complications and the risk of death is as low as 1-2%. 10 But, in spite of this good news, it’s still important to discuss the risks and benefits of heart bypass surgery with your healthcare provider. 

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Source: Verywellhealth