What is CABG?

Coronary artery bypass graft surgery (CABG) is a procedure used to treat coronary artery disease in specific situations. Coronary artery disease (CAD) is the narrowing of the coronary arteries (the blood vessels that supply oxygen and nutrients to the heart muscle), caused by a build-up of fatty material (plaque) within the walls of the arteries. This build-up (atherosclerosis) narrows the arteries, limiting the supply of oxygen-rich blood to the heart muscle.

One way to treat the blocked or narrowed arteries is to bypass the blocked portion of the coronary artery with another piece of blood vessel. (Like when the highway is blocked, a service road is opened up to ease the traffic!) Blood vessels, or grafts, used for the bypass procedure are taken from within the patient’s own body. It is usually an artery from the chest wall (Left Internal mammary / thoracic artery) or an artery from the hand (radial artery). Sometimes the saphenous vein from the leg nay be used.

Traditionally, in order to bypass the blocked coronary artery in this manner, the chest is opened in the operating room and the heart is stopped for a time so that the surgeon can perform the bypass. In order to open the chest, the breastbone (sternum) is cut in half and spread apart. Once the heart is exposed, tubes are inserted into the heart so that the blood can be pumped through the body during the surgery by a cardiopulmonary bypass machine (heart-lung machine). The bypass machine is necessary to pump blood while the heart is stopped and kept still in order for the surgeon to perform the bypass operation.

While the traditional “open heart” procedure is still performed sometimes, more often we perform the “Off-pump” or “Beating-heart” procedure, in which the heart does not have to be stopped. This is done with the help of a stabilizer like the Octopus. Other minimally-invasive procedures, such as key-hole surgery (performed through very small incisions) are increasingly being used.

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Risks of CABG

Possible risks associated with coronary artery bypass graft surgery include, but are not limited to, the following :
  • Stroke
    This is due to either hypotension (low BP) during surgery or may be due to co-existent blockages in the carotid artery (blood vessels in the neck which supply blood to the brain. We always get an ultrasonography (Doppler) of the carotid arteries to rule out any significant blockages. Also, with the beating heart technique, wherein blood pressure fluctuations are minimal the risk of stroke is very low (less than 1%)
  • Renal failure
    This is a risk in patients with kidney problems (Creatinine > 2 mg% ). In these patients, we try to optimize the renal status before surgery in consultation with a nephrologist. In patients with normal renal function, the risk of post-operative renal problems is rare.
  • Bleeding
    Patients who are on blood thinners (Aspirin / Clopidogrel) before surgery can have an increased risk of bleeding during and after surgery. In elective surgeries, we stop these medications 3-5 days before surgery. In certain situations, we cannot stop these medicines and patients may require blood transfusions. In my practice at Jupiter hospital, we manage almost 70% cases of bypass surgery without blood transfusion by stopping these medicines and using a cell saver to salvage blood lost during surgery.
  • Infection
    Diabetic patients are at an increased risk for infection. However, with good antibiotic cover and strict sugar control, this is also a rare occurrence. Most patients (who are on oral anti-diabetic tablets) would require Insulin for about 4 weeks after surgery till complete wound healing.
  • Pneumonia and Breathing problems
    This is a risk in patients with prior lung problems like asthma and smokers. These patients require a prior chest physician opinion and physiotherapy to optimize lung status prior to surgery
  • Despite the risks associated with bypass surgery, it is extremely safe with overall risk in the range of 0.5 to 1%

Before the procedure

  • Generally we get the patient admitted to the hospital a day prior to the operation. You have to come to the hospital fasting by 8 AM. This is to get the necessary blood tests, ultrasound, X-ray of the chest, 2D echo of the heart and any other tests that may be necessary. The anaesthetist will examine in preparation for the anaesthesia for surgery.
  • If you are pregnant or suspect that you are pregnant, you should notify your doctor. Notify your doctor if you are sensitive to or are allergic to any medications, iodine, latex, tape, or anaesthetic agents (local and general). Notify your doctor of all medications (prescription and over-the-counter) and ayurvedic or homeopathic supplements that you are taking.
  • If you smoke, you should stop smoking as soon as possible prior to the procedure. This will improve your chances for a successful recovery from surgery and benefit your overall health status.
  • You and your family will also have an opportunity to again review the procedural details and ask the surgeon, cardiologist and anaesthetist about any last-minute queries that may crop up.
  • You will be asked to sign a consent form that gives your permission to do the surgery. There will be a General Consent form, a High Risk Surgery Consent, one for Anaesthesia and a consent form for Radial artery harvest. Read these forms carefully and ask questions if something is not clear.
  • You will be asked to fast for eight hours before the procedure, generally after midnight.

During the procedure

Generally, a coronary artery bypass surgery follows this process:
  • You will be positioned on the operating table, lying on your back. An intravenous (IV) line will be started in your arm or hand. The anaesthetist will continuously monitor your heart rate, blood pressure, breathing, and blood oxygen level during the surgery. Once you are sedate and under general anaesthesia,, a breathing tube will be inserted into your throat and into your trachea (breathing tube) to provide oxygen to your lungs, and you will be connected to a ventilator, which will breathe for you during the surgery. Additional catheters will be inserted in your neck and wrist to monitor the status of your heart and blood pressure, as well as for obtaining blood samples. A catheter will be inserted into your bladder to drain urine.
  • The skin over the surgical site will be cleansed with an antiseptic solution. The surgeon then will start the operation by making an incision (cut) down the center of the chest over the sternal bone. Simultaneously, incisions will be made in one or both of your legs or one of your forearms to obtain a section of the saphenous vein or radial artery respectively. The sternum (breastbone) will be divided and spread apart to expose the heart. The left internal mammary artery (LIMA) is then harvested for the bypass grafting.
  • Once the chest has been opened, the area around the artery to be bypassed will be stabilized with a special type of instrument (Stabilizer). The rest of the heart will continue to function and pump blood through the body. The cardiopulmonary bypass machine and the perfusionist who runs it are kept on stand-by. The surgeon will perform the bypass graft procedure by sewing one end of a section of vein over a tiny opening made in the aorta, and the other end over a tiny opening made in the coronary artery or internal mammary artery just beyond the blockage. You may have more than one bypass graft performed, depending on how many blockages you have and where they are located. Before the chest is closed, all the grafts are examined to make sure they are working. Tubes will be inserted into your chest to drain blood and other fluids from around the heart. The sternum is then closed with steel wires. A sterile bandage or dressing will be applied.

After the procedure

  • In the hospital
    After the surgery you will be shifted to the Intensive Care Unit (ICU) to be closely monitored. If overnight vital status is maintained, you will be extubated (breathing tube is removed) in the morning. The usual ICU stay is for two days. During this time you will be gradually weaned off supports, encouraged to breathe and do chest physiotherapy and gradually mobilized out of bed. Once the stomach tubes have been removed and your condition has stabilized, you will be given liquids to drink. Your diet will be gradually advanced to more solid foods as you are able to tolerate them. On the third day the chest drainage tubes will be removed and you will be shifted to the ward room.

    The surgical incision may be tender or sore for a few days after a CABG procedure. This is easily controlled by regular pain medications. Your recovery will continue to progress. Your activity will be gradually increased as you get out of bed and walk around for longer periods of time. Your diet will be advanced to solid foods as you tolerate them. Usually by the 5th postoperative day you will be ready to go home.
  • At home
    Once you are home, it will be important to keep the surgical area clean and dry. Your doctor will give you specific bathing instructions. The sutures or surgical staples will be removed during a follow-up visit.

    In most instances, recovery is rapid. However, you should not drive for at least 2 months after surgery as that’s the time needed for the sternum to heal. During these 2 months you should continue wearing the chest belt given in the hospital and also avoid lifting heavy weights. Continue doing the deep breathing exercises and chest spirometry as instructed by the physiotherapist. Sexual activity can be resumed in three to four weeks. The main limitation to activity is healing of the sternum which may take 8 to 12 weeks.

    Following bypass surgery, a patient can expect a recovery period of about 4 to 6 weeks. People who do more sedentary work often return to work after six weeks. It may be up to 8 weeks before patients can return to more-physically-demanding jobs. Full energy levels usually start to return in about three months. Most patients can expect to feel more tired than usual and their stamina may not yet be completely normal. After six months, most patients are back to normal. Most people who have bypass surgery are able to resume normal activities, and over 95 percent have a substantial improvement of angina. However, new blockages may occur over a period of time which may require an angioplasty or a second bypass. The risk can be reduced by discontinuing smoking, eating a healthy diet, taking prescribed medications and getting regular physical activity.

    Nearly all patients benefit from cardiac rehabilitation after surgery. Rehabilitation usually focuses on lifestyle changes, including diet and exercise as well as psychological issues. These programs are tailored to each person because individual circumstances vary and different people go into surgery at different levels of health.

    Bypass surgery plays an important role in treating coronary artery disease, but it isn’t a cure. Surgery can improve symptoms and even prolong life when the left main coronary artery or multiple vessels are bypassed, but it doesn’t get rid of the disease. Patients must manage the disease with exercise, proper diet, medications and other lifestyle changes recommended by their physician.
    Patients should be seen at regular intervals by their local physician to monitor the control of risk factors, particularly cholesterol, blood pressure, and diabetes, and at least annually by their cardiologist to monitor their coronary artery disease.