For several weeks before bypass surgery, patients who smoke will be advised to stop smoking. Many surgeons also advise their patients to stop taking aspirin to minimize the risks of excessive bleeding during and immediately after surgery. Patients will also be asked not to eat or drink anything after midnight before surgery. Certain medications, especially those that affect blood clotting, may be reduced or stopped. Patients should discuss their medication schedules with their physician.

The patient is usually admitted the morning of surgery. A few days before surgery, the patient undergoes a number of tests, which include an x-ray, blood tests, urinalysis and an electrocardiogram (EKG). The patient’s blood is typed and cross–matched with units of donor blood, according to the surgeon’s wishes. Blood transfusions may not be needed. Patients should know, however, that blood banks test blood to screen donor blood for most major diseases, such as hepatitis or AIDS.

The patient will be given specific pre-operative medications and is then prepared for surgery. The chest, groin and leg areas are shaved, and a bacteria-killing (bactericidal) solution is applied to the operative site and surrounding area. The patient is then sedated with medication given through an intravenous (I.V.) line in the arm or hand. As soon as the patient is asleep, an anesthetic inhalation gas (general anesthesia) is continuously administered through an endotracheal tube (breathing tube) and constantly monitored by the anesthesiologist.

After the patient is asleep, a device called a Swan-Ganz catheter is often inserted through a needle stick into the jugular vein (in the neck) and threaded to the pulmonary artery (which goes from the heart to the lungs). The catheter is used to measure heart function, measure the pressures in both the heart and lungs, and to give any necessary medications. The endotracheal tube, which was inserted into the mouth and down the windpipe (trachea), is used to maintain an airway. A urinary catheter is also inserted and connected to a collection bag to measure the patient’s urine output. 

An incision is then made in the chest, through the breastbone (sternum), and the two halves of the breastbone are divided (median sternotomy). A medical device called a retractor is used to pull back the two halves of the breastbone to give the surgeon plenty of room to work. The ribs are not divided, reducing discomfort during recovery. 

The functions of the heart, including blood flow and oxygenation, are rerouted through a heart-lung machine. While the machine takes care of the heart’s functions, the heartbeat can be carefully stopped by administering a cardioplegic solution. In total, the heart will remain stopped for about 30 to 90 minutes during the four to five hours (on average) of surgery.

Before the heart is stopped, the blood vessel(s) to be used as grafts are removed from their source location. If they are located in the chest, one end of the blood vessel(s) may remain connected to the larger artery it originated from, or it will be sewn to the aorta, depending on which blood vessel is used for the graft. The other end is sewn into place below the blockage in the coronary artery. After the graft(s) are completed, and blood is successfully flowing around the blockage, the heart is restarted and the patient is removed from the heart-lung machine. Finally, when normal blood flow and heartbeat are re-established, the surgical site is carefully closed layer by layer. The sternum is usually closed with wire and the surface incision is closed with staples or sutures, depending on the surgeon’s preference.

Although coronary bypass is a relatively safe surgery with an extensive history in patients, researchers are still looking for ways to improve it. For instance, studies are underway to investigate new ways of grafting blood vessels. One method involves a “sewing” device consisting of two sets of hooks. One set holds the graft; the other makes the attachment to the aorta. In the small group of individuals having undergone the procedure, the graft was connected in less than two minutes (versus up to seven minutes with current methods). Researchers also noted a better quality of connection. Moreover, it resulted in less time required on the heart-lung machine.

Another technique, still in the animal testing stages, involves connecting grafts with an adhesive. Researchers think that either procedure may someday find use in minimally invasive bypass surgery and may make the heart-lung machine unnecessary in standard coronary bypass surgery. 

Coronary artery bypass surgery can also be performed in conjunction with other cardiac surgical procedures to treat other conditions that may have occured at the same time (e.g., stenosis, leakage of cardiac valves). A transesophageal echocardiogram is often required during surgery to detect these abnormalities and document the success of the surgery.