Coronary Artery Bypass Grafting (CABG) – Simplified

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A coronary artery bypass graft surgery, sometimes called a CABG, is one of the most commonly performed surgeries in India. In this post, we talk briefly about the procedure, when it is performed, and what the possible risks of the procedure are. If you are due to undergo bypass surgery, this article will hopefully give you a good idea about what to expect.

Click on the tabs below for information on each question.

What is a CABG?
A CABG is a surgery that is performed in patients who have extremely narrowed heart arteries that cannot be treated sufficiently with medicines or angioplasty. The principle behind a CABG is that short bypasses are created when blood flows directly from the aorta into the heart arteries without having the blood flow through the diseased sections. This way, sufficient amount of blood that is rich in oxygen and nutrients can be supplied to the heart muscle.
When is a coronary artery bypass graft surgery performed?
The primary reason for performing a CABG surgery is the presence of severe coronary artery disease. This may involve just one coronary artery or multiple coronary arteries. The decision that a CABG would benefit the patient more than medical therapy alone or angioplasty is often made by the cardiologist who has access to the patient’s history and has reviewed the angiogram results.

The goal of CABG is to help relieve the patient’s symptoms such as chest pain and breathlessness. Most patients who undergo CABG tend to be those who suffer from diabetes mellitus as this condition is often associated with multiple coronary artery disease. The reason for this is that CABG offers patients a good quality of life and studies have shown that patients have an excellent long-term outcome.

How is CABG performed?
Prior to performing the surgery, patients will have an opportunity to discuss the procedure in detail with the cardiothoracic surgeon. It is strongly recommended that patients clear any doubts they may have during this meeting and make an informed decision regarding whether or not they would like it done depending on what they learn and depending upon the knowledge of the risks and benefits.

Once the patient has agreed to undergo the surgery and consent has been obtained, the patient is taken to the operating room where the chest wall is cleaned with antiseptic solution and the body is covered in sterile drapes. The patient is administered a general anaesthetic and Their vital signs are monitored throughout the procedure.

A long incision is made in the middle of the chest extending all the way from the bottom of the neck to the lower part of the breast bone. Once the skin incision has been made, a sort will be used to open up the breast bone and expose the heart.this procedure is called a sternotomy.

The heart is then cooled with the help of ice cold saltwater and a preservative solution is injected into the individual heart arteries. This slows down the heartbeat and decreases the amount of blood that close to the heart while keeping the heart healthy. Doing so helps the surgeon perform the procedure quickly and without complications. This aspect of the surgery where the heart is called down and slow down is called ‘cardioplegia’.

Once this has been done, patients are placed on a ‘cardiopulmonary bypass’. This is a procedure where a plastic tube is placed within the right atrium so that the oxygen poor venous blood that enters the right atrium is transferred through a thin sheet that end which is the blood with oxygen. This sheet is called a membrane oxygenated and is present within a machine known as the heart-lung machine. The blood is then pumped back from the heart-lung machine into the body and this way oxygenated blood is circulated through the body when the heart is slow.

In order to minimise the amount of blood that is lost during surgery, the lower part of the aorta is clamped with a surgical clamp. This makes surgery a lot more simpler and the surgeon can clearly see each and every part of the heart without having to worry about blood blocking their view.

Once the heart has been prepared this way, it is time to perform the bypass surgery.

Coronary Artery Bypass Grafting

The bypass surgery primarily involves the placement of blood vessels from the aorta All the way to a point beyond the narrowing in the heart arteries. These blood vessels are called grafts. The commonly used blood vessels include the saphenous vein that lies in the legs, the left internal mammary artery which is an artery that supplies the left side of the chest wall and the radial artery which is an artery that supplies the hand. almost all patients will have the left internal mammary artery utilised during the bypass surgery as they have an excellent rate of staying open for a number of years after the operation as compared to the saphenous vein grafts. However, given that there is only one left internal mammary artery, it can be only utilised for one graft and the other blood vessels are often grafted with either the radial artery or the saphenous vein.

After the bypass has been successfully created, the clamp that surrounds the aorta is removed. This allows for blood to flow down the grafts into the coronary arteries. The patient is then taken off cardiopulmonary bypass and the heart is brought back to normal temperature so that it beats at a normal rate. The breast bone is then closed with the help of sternal wires (which are made of stainless steel) and a small plastic tube is kept in place in order to allow any excess fluid to drain out of the chest wall. Patients may have other tubes present in the chest wall to allow for the free drainage of fluid that may accumulate.

Following the surgery, patients are transferred to the intensive care unit for observation. If all is well and there are no immediate complications, patients will be transferred to the ward for monitoring. During this time, they will be encouraged to start walking under supervision and if there are no problems, they would be discharged home for further recovery.

How long does the surgery take?

A bypass surgery takes anywhere between 4 to 5 hours to perform.

What are the risks and complications of CABG?

As is the case with any kind of surgery, coronary artery bypass grafting also has certain risks associated with it. Some of the common complications that are seen in patients who undergo coronary artery bypass grafting include –

1. Irregular heartbeat – This is seen in around 30% of patients who undergo CABG. The irregular heartbeat is a condition called atrial fibrillation. It is not life-threatening and can be treated easily with medical therapy.

2. Pain at the site of surgery – It is not uncommon for patients experience a small amount of pain at the site where the breast bone had been opened up. This pain can be managed with simple painkillers and takes a few weeks to completely disappear.

3. Infection – This is an uncommon side-effect and is seen in about 4% of patients who undergo CABG. Infections can occur at the site of surgery and rarely may occur in the chest or lungs. Treatment options are simple and infections can be managed effectively with the use of antibiotics.

4. Kidney function problems – Around 5% of patients who undergo CABG may have problems with the kidneys. Reassuringly, this is short lived and the kidney function returns to normal fairly quickly. Rare cases may require dialysis to speed up the process.

5. Memory loss – A small number of patients may experience slight problems in memory and difficulty concentrating after they have undergone a CABG. The chance of this occurring is less than 5%. In about 2% of cases, patients may develop a stroke which can affect the individual’s movements, speech and even quality of life. On rare occasions, this can be life threatening.

6. Heart attack – Within the first month of undergoing bypass surgery, patients may experience another heart attack. This may occur during the surgery or shortly after.

What happens after surgery?

Following surgery,  patients will be observed for a few days on the ward during which time they will be asked to gently walk around in an attempt to restore their normal activity. Patients may be asked not to take a bath for a day or two but this order is revoked  soon after. A normal diet can be commenced fairly quickly after surgery  door in the initial stages, patients may be asked to consume just a liquid diet.

Am I at risk of developing complications?

This is a difficult question to answer. The risk of surgery depends upon numerous factors and is not the same for each and every patient. The risk can be assessed in detail by the surgeon performing the procedure prior to it being conducted. However, it is good to know the different factors that may affect your risk if you are undergoing CABG.

1. Age – The older you are, the higher the risk.

2. Female gender – Women tend to have a higher risk of complications from CABG. This may be related to the fact that they develop heart disease at an older age when compared to men.

3. Associated medical problems – in patients who have other medical conditions for which they are receiving treatment, the risk of CABG is a lot higher. For example, in patients who have underlying lung disease or conditions such as diabetes, the risk and complication rate is greatly increased.

4. Obesity – Obesity is a well-recognised risk factor in the development of heart disease and also plays a role in the development of complications following CABG.

5. Having multiple vessels grafted – patients who have three or more heart arteries grafted during surgery tend to have a higher chance of developing complications.

In order to assess the risk, surgeons will take a detailed history from the patient and input their data into an authenticated scoring system that estimates the patient’s risk and benefit of undergoing CABG. If the benefits of surgery outweigh the risks, the surgery is performed. On the other hand, if the risks outweigh the benefits, surgery will not be performed and medical therapy would be pursued.

What is 'off pump' coronary artery bypass grafting?

This type of coronary artery bypass graft surgery is slightly different to the conventional way that this surgery is performed. As you may have seen above, the heart is often stopped  before performing CABG in order to make it easy to  stitch the grafts in place.  However, in an off pump coronary artery bypass graft, the heart continues to beat  as usual and is not stopped using any medication. Sometimes, this procedure is called ‘beating heart surgery’.

It is believed that an off pump CABG has a lower risk and lower complication rate as compared to the conventional CABG.

What is minimally invasive coronary artery bypass graft surgery?

Minimally invasive coronary artery bypass graft surgery (sometimes called MICAS) is a relatively new kind of bypass surgery  where  the vessels are repaired and a graft is inserted by making a very small incision in the chest wall. This incision is a a lot smaller than what is performed in a conventional CABG.

One of the main advantages of minimally invasive surgery is that the hospital stay is a lot shorter  compared to conventional CABG. However, minimally invasive surgery can be a lot more expensive and  may not necessarily be the best option for all patients with coronary artery disease requiring surgery.

Is depression common after CABG?

You may have heard about patients getting depressed or becoming  emotionally low after undergoing CABG. In fact, this is a well-recognised reaction to surgery and is easily overcome with the help and support of friends and family. It usually occurs because the overwhelming nature of the operation can sometimes be a wake-up call to patients who have  not followed appropriate lifestyle modifications or who have undergone a life-threatening heart attack which they have survived.

Other frequently asked questions

1. When can I return to work?

Individuals who perform sedentary jobs can return to work after 4 to 6 weeks. However, those individuals who perform more physical activity in their job may need to stay home little bit longer. It is strongly recommended that all patients who undergo CABG speak to their doctor about when the appropriate time  is for them to return to work.

2. When can I resume normal sexual activity?

Patients can resume normal sexual activity whenever they please. However, it is recommended that they do not indulge themselves in aggressive sexual activity  for at least a few weeks following surgery.  Once their exercise capacity has returned to normal and they are back to leading a normal quality of life, sexual activity can also be completely normal.

3. When can I start driving?

Patients can start driving soon after surgery but it is recommended that their wait a few weeks at least.

Dr Vivek Baliga B
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