Coronary Artery Bypass Grafting: CABG

What does Coronary artery Bypass grafting or CABG means?

Bypass means an alternate route. A coronary bypass operation involves taking a short length of vein, usually from the thigh (the saphenous vein), and using it to allow blood to bypass the blockage in an artery. The internal mammary artery is also used as a graft. This artery lies inside the front of the chest. There is one on each side of the breastbone. The lower end of this artery is freed and sewn to the coronary artery beyond the blockage. The other end is left attached. Blood is thus rerouted into the coronary arteries. Other arteries as the radial artery and gastroepiploic artery can be used as a bypass graft also.

Before your surgery:

• You will be admitted the day of or day before your surgery. You will be given diagnostic tests, a physical examination, and will be seen by members of the cardiac surgery and anesthesia teams. A nurse will discuss the Intensive Care Unit (ICU), postoperative recovery and discharge planning procedures with you and your family.
• If you smoke, you should stop. Smoking constricts the coronary arteries, produces excess secretions in the lungs, raises blood pressure and increases the heart rate. The potential for complications increases after surgery if you continue to smoke.
• Blood thinners as aspirin, should be discontinued before surgery.
• In advance of your surgery, Blood will be prepared for you to be used whenever needed. Your cardiac surgeon will determine the amount required.Family members and friends may also donate blood for you if they meet eligibility criteria.
• Until midnight the day before your surgery, you may eat and drink as usual. After midnight, however, do not eat or drink anything. This helps decrease any nausea and vomiting associated with anesthesia. If you have prescribed medications, use only a small amount of water.

On the Day of Surgery

Anesthesia Doctors will start to work on the Holding Area

You will be transported to the pre-operative area outside the operating room one hour prior to surgery. Here, the anesthesia team will insert an intravenous line (IV) to sedate you. A local anesthetic is injected into the skin of the neck, and a larger catheter is introduced into the jugular vein and threaded through the right side of the heart into the pulmonary artery. This catheter, called a Swan-Ganz catheter, can be used not only to give medicines but also to measure cardiac and pulmonary-arterial pressure and the amount of blood that the heart is pumping. Although many heart surgical teams routinely use the Swan-Ganz catheter, not all of them do. It depends on the preference of the surgeon, the anesthesiologist, and the heart surgery team. Another catheter is then placed in one of the arteries so that the arterial blood pressure can be monitored and blood samples can be drawn to check the arterial blood’s oxygenation level. This catheter is usually placed in one of the wrist arteries, often the radial artery. If a radial artery will be used for one of the bypasses, the other wrist can be used, or the catheter can be placed in the femoral artery by inserting it through the groin.

Once the operating room team is prepared for your surgery, the anesthesiologist will take you to the operating room. You will be anesthetized (put to sleep); an endotracheal tube (breathing tube) will be inserted; and all your lines will be connected to a TV like machine to monitor your heart, blood pressure, respirations and other bodily functions. After sleeping a catheter is placed into the urinary bladder to calculate your urine output during surgery. Urine output is an excellent monitor for your kidney and heart functions.

Now surgeons are ready to work:

Your chest and legs are swabbed with antiseptic soap solutions, and sterile operating drapes are placed on and around the patient. Now the team is ready to make the first incisions, but immediately before this incision, a timeout is done. In this timeout the surgeon, anesthesiologist and nurses will reconfirm your name, your medical diagnosis and the type of surgery that will be performed. This is one of the important steps that prevent problems of the wrong patient and the wrong procedure.

Usually one surgical team will make one or more shallow incisions in the leg and harvest the vein for the bypass while the other team opens the chest.

To open the chest, an incision is made in the skin. Beneath that, a layer of fat and muscle is cut through to expose the breastbone (sternum). A saw is used to open the entire length of the sternum.  With the chest open, thee left internal mammary artery is freed.

A blood thinner, called heparin is given intravenously into the bloodstream to prevent the blood from clotting while the circulation is supported by the heart-lung machine.

The sac surrounding the heart is opened and the heart is exposed. Several plastic tubes are connected to the heart using special sutures. These tubes will then connect the patient to the heart – lung machine.

The tubes in the right atrium return unoxygenated blood from the patient’s venous system to the heart-lung machine. The machine will then oxygenate the blood and return it to the patient through one of the tubes connected to the aorta.

After these tubes are in place, cardiopulmonary bypass is initiated by telling the technician or perfusionist running the heart-lung machine to turn on the machine. The heart-lung machine then takes over the function of the heart and lungs. After it is activated, most surgeons will cool the patient’s body temperature to some level, but not all surgeons do this. The heart is then stopped by a special solution called cardioplegia.

With the heart stopped and the body supported by the heart-lung machine, the coronary arteries that are to be bypassed are identified. The coronary arteries are opened beyond the obstruction and measured.  With the coronary opened beyond the area of obstruction. One end of the graft is hooked to the coronary artery with small stitches usually made out of polypropylene. After all the bypasses, are sewn to the coronaries, the other ends are joined to the aorta or, in some cases, to other veins or arteries. If the internal mammary artery is used, one end is already connected to the arterial system.

The bypasses are now complete and the patient’s body is rewarmed. The heart usually restarts on its own but sometimes needs the help of a temporary pacemaker or an electrical shock.

After the heart has started, the patient is weaned from the heart-lung machine by slowly turning the heart-lung machine off as the patient’s own heart and lungs take over. In some cases, the heart is too weak to take over for whatever reason, and another attempt or two will be made at letting the heart take over. If these are unsuccessful, an intra-aortic balloon pump is used, which is a pump that is threaded through an artery, usually through the groin, and connected to an external power source. There is a balloon on the tip of a long, thin tube that inflates and deflates in synchrony with the heart, helping the heart to pump blood as well as increasing the blood going to you coronary arteries.

In more severe cases when the heart does not take over, some form of ventricular assist device  may have to be used. This is relatively uncommon. Most patients are weaned from bypass without the use of any type of mechanical support on the first attempt.

The operative field is revised for any bleeding points which are secured. The sternum is then closed with permanent stainless steel wire. The muscle and skin are then closed.

Now your surgery is over and you are ready to be transferred to the ICU .