CABG (Coronary Artery Bypass Graft) also known as Coronary Artery Bypass Surgery is a treatment for patients with Coronary Artery Disease (CAD). Coronary artery disease is blockage or narrowing of one or more of the coronary arteries.
Coronary arteries are responsible for supplying your heart muscle with blood. If too much plaque is built up in them, it can narrow or even block your blood from passing through. In case your heart can't get enough blood or oxygen, you can have a heart attack.
Coronary artery bypass surgery helps to restore normal blood flow to the heart by creating a bypass around the blocked artery. This surgery is done by using a healthy blood vessel called a graft.
Graft usually comes from your own arteries and veins located in the leg, chest or arm. This graft creates a new pathway to carry oxygen-rich blood to the heart.
Type of Grafts used in the CABG
Internal thoracic arteries
- Internal thoracic artery (ITA) grafts or internal mammary arteries are the most commonly used bypass grafts.
- We have two internal thoracic arteries in our chest. If these arteries are to be used for bypass surgery, they need to be kept intact at their origin because they have their own blood supply.
- The other end of the artery is cut and sewn to the coronary artery below the site of the blockage. In case the artery needs to be completely removed, then it is called a "free" artery.
The Radial Artery Graft
- The radial artery is another common type of arterial graft used in bypass surgery. There are two types of arteries in the arm, the radial and ulnar arteries. The ulnar artery is responsible for the delivery of blood to the arm, so it does not have any side effects if the other one can be removed and used as a graft.
- Initially, some people after surgery may feel numbness in the wrist but this sensation usually goes away as time passes.
- This radial artery graft is known to have good results, although long-term outcomes are not fully known.
- In case of unavailability of the radial artery and internal thoracic artery, Inferior Epigastric artery which leads to the abdominal wall and Gastroepiploic artery which is a branch leading to the stomach can be used for the surgery.
- These two arteries are more difficult to use but can be a good option if other options are not available.
Not only the arteries but Saphenous veins that are available in legs can be used as bypass grafts. Removal of these veins does not require a long incision. It only requires 1-2 incisions at the knee and a small incision at the groin. This type of removal leads to faster recovery than traditional surgery.
Medical science is making continuous efforts to improve the results with vein grafts; however, they are still more vulnerable to failure in the long term.
Who needs Heart Bypass Surgery?
- If a person has severe chest pain caused by narrowing of several of the coronary arteries, leaving the muscle short of blood during very light exercise and even the rest. The patient may have already tried other things such as angioplasty and stents but that didn't help enough.
- If the left main coronary artery is blocked or narrowed, then the person needs to go through a bypass surgery because this artery is responsible for supplying most of the blood to the left ventricle.
- If a person has more than one diseased coronary artery and the heart's main pumping chamber, the left ventricle isn't functioning well.
- If a person had stent placement but the artery has narrowed again or if he/she had a previous stent placement or angioplasty that hasn't been successful.
- Coronary bypass surgery may also be performed in an emergency such as a heart attack. Emergency surgery becomes the only option when the doctor sees that the patient is not responding to other possible treatments.
Test and Diagnosis
A general physical examination of the patient is done. Many tests are performed to find out the clogged arteries, how much they're clogged, and if there's any heart damage.
Usually, the following tests are advised to the patient:
Electrocardiogram (ECG): This test is performed to record the heart's electrical activity.
Stress Test: Many tests are performed to find out if the heart is working hard due to physical exercises.
Echocardiography: Echocardiography provides information about the size and shape of the heart and how well the heart's valves and chambers are working using sound waves.
Coronary Angiography: Coronary Angiography helps the doctor to find blockages that can be the reason for a heart attack. It is done using dyes to study the flow of blood through the coronary arteries.
Following factors will help the doctor to determine whether a person is a right candidate for CABG or not. These are:
- Severity and existence of coronary heart disease
- Stage and location of blockages in coronary arteries
- How a patient responds to other treatments
- The state of the patient's health
- Other underlying medical conditions
What can be expected from Coronary Artery Bypass Surgery?
- To prepare for coronary bypass surgery, the doctor will give specific instructions to the patient about changes in his/her diet, any activity restrictions or medications that should be followed before surgery.
- The patient will need several pre-surgical tests, often including blood tests, chest X-rays, a coronary angiogram and an electrocardiogram.
- Most people are admitted to the hospital in the morning of the day of the surgery.
- It usually takes about four to six weeks to recover to the point where a patient can resume work and perform daily chores. So, the patient is advised to make arrangements for the weeks following the surgery.
During the surgery
Traditional Coronary Artery Bypass Grafting
- This type of surgery usually takes 3 to 5 hours; however, it totally depends on the number of arteries being bypassed.
- The patient will be given general anesthesia for the surgery and during the surgery, the anesthesiologist keeps a check on the blood pressure, heartbeat, breathing, and oxygen levels of the patient. A breathing tube is placed in your lungs through the throat and the tube is connected to a ventilator.
- The surgeon made an incision down the centre of the chest. The chest bone is cut and the ribcage is opened so that the surgeon can reach the heart of the patient.
- With the help of medicines, the heartbeat of the patient is stopped so that the surgeon can operate on the heart while it is not beating. The patient is also given some medication to protect his/her heart function when it is not beating.
- During the surgery, a heart-lung bypass machine keeps oxygen-rich blood moving throughout the patient's body.
- An artery or vein is removed from the patient's body, for example, from the chest or leg of the patient and it is prepared to be used as a graft for the bypass.
- After the grafting is done successfully, blood flow to the heart is restored. In most of the cases, the heart starts beating again on its own. However, sometimes, mild electric shocks are required to restart the heart.
- After the heart starts beating, the patient is disconnected from the heart-lung bypass machine, and tubes are inserted into the chest to drain the fluid.
- The surgeon uses wires to close the chest bone which stays in the body permanently. After the healing of the chest bone, it will become as strong as it was before the procedure.
- The surgeon uses staples or stitches to close the skin incision. The breathing tube can be removed when the patient is able to breathe without it.
Non-traditional Coronary Artery Bypass Grafting
Non-traditional CABG includes minimally invasive CABG and off-pump CABG.
Off-Pump Coronary Artery Bypass Grafting
This Coronary Artery Bypass Grafting can be used to bypass any of the coronary arteries. It is also called beating heart bypass grafting because the heart isn't stopped during the surgery. Instead, only the part of the heart where grafting is being done is steadied with the help of a mechanical device.
Minimally Invasive Direct Coronary Artery Bypass Grafting
Nowadays, there are many types of minimally invasive direct coronary artery bypass (MIDCAB) grafting available. This surgery only requires small incisions rather than opening the chest bone to reach the heart. This procedure sometimes needs a heart-lung bypass machine.
- This procedure works only when one or two coronary arteries need to be bypassed.
- A series of small incisions are made between the ribs on the left side of the chest directly over the artery that is to be bypassed.
- The incisions are usually about 3 inches long.
- In this kind of procedure, the left internal mammary artery is used mostly for the graft.
- A heart-lung bypass machine isn't required during this procedure.
Port-access coronary arteries bypass
- This surgery is done through small incisions made in the chest.
- Artery or vein grafts are used and a heart-lung bypass machine is used during this procedure.
- This type of procedure works for even smaller keyhole-sized incisions.
- One incision is made and a small video camera is inserted to show the heart.
- The surgeon uses remote-controlled surgical instruments to perform the surgery.
- Sometimes, a heart-lung bypass machine is used during this procedure.
Heart Surgery Recovery
Recovery in the Hospital
After surgery, the patient needs to spend 1 or 2 days in an intensive care unit (ICU). The doctor will keep a check on the oxygen levels, blood pressure, and heart rate.
After spending 1 or 2 days at ICU, the patient will be transferred to a less intensive care area in the hospital for 3 to 5 days.
Recovery at Home
The doctor will give some specific instructions that the patient need to follow at home. These are:
- How to recognize signs of infection
- How to care for healing incisions
- When to make follow-up appointments
- When to call the doctor right away
Full recovery from conventional CABG may take 6-12 weeks or more. However, less recovery time is needed for non-traditional CABG.
The patient is advised when he/she can start physical activity again. Recovery time varies from person to person, but there are some standard timeframes that we need to follow. In most of the scenarios, returning to work after six weeks is common if your job doesn't involve demanding and specific physical activity.