Bypass Surgery - Coronary Artery Bypass Surgery

Also called: Coronary Bypass Surgery, Heart Bypass Surgery, Coronary Artery Bypass Grafting, CABG, Coronary Artery Bypass

Summary

The conorary artery bypass graft (CABG) is the gold-standard surgical treatment for coronary artery disease (CAD). It is a relatively safe procedure that is performed thousands of times every year for treating CAD. CAD is characterized by the hardening and narrowing (atherosclerosis) of the coronary arteries, which supply oxygen-rich blood to the heart. If left untreated, CAD may lead to a heart attack.

During CABG, a surgeon harvests a segment of a healthy blood vessel (either an artery or vein) from another part of the body and uses it to create a detour or bypass around the blocked portion of the coronary artery. As a result, oxygen-rich blood can flow more freely to nourish the heart muscle. Depending on the number of blocked coronary arteries, a patient may need one, two, three or more bypasses.

For various medical reasons, only about one-tenth of CAD patients even need this type of heart surgery. Those who have the surgery need to stay in the hospital for at least three to five days afterward while recovering. After returning home, further recovery time will be necessary.

The CABG is one of the most commonly performed surgeries in the United States. According to the American Heart Association, more than 467,000 CABGs were performed in 2003. Also increasing is the age at which the procedure can be safely performed, as individuals 80 years of age and older have benefited from CABG. Although there are risks associated with any surgery, the potential life-saving benefits of a CABG usually outweigh the risks.

Conorary artery bypass surgery is often known simply as a “bypass” and is referred to as such in this article. Surgeons also perform other types of bypass surgery to treat diseases in other parts of the body, including peripheral vascular disease.

About coronary bypass

The goal of conorary artery bypass graft surgery (CABG) is not to repair or remove any blocked arteries, but to detour blood around a blockage in a coronary artery and reestablish the flow of oxygen-rich blood to the heart. To create the detour, a segment of a blood vessel is taken from another part of the body. The segment may be taken from one of the following: The saphenous vein from the leg is commonly used. The internal mammary artery from the chest is usually preferred for key artery branches because it tends to remain open longer. Some call it the internal thoracic artery. The radial artery from the arm and sometimes arteries from the stomach (gastroepiploic artery) may also be used as bypass grafts. Depending on which blood vessel is used, one end is either sewn to the aorta or may remain connected to the larger artery where it originated. The other end is attached (grafted) beyond the blockage in the coronary artery. As a result, blood can flow around the blocked area, increasing the supply of oxygen and nutrients to the heart muscle. Bypass surgery may be recommended for individuals with a history of any of the following: Narrowing in several coronary artery branches (common in people with diabetes) Severe narrowing in the left main coronary artery Blockage in the coronary artery or another condition that may not or has not responded to other treatments (e.g., angioplasty) Severe angina Bypass surgery carries some risks, including a less than 5 percent chance of heart damage and a less than 2 percent chance of death. Studies show that women have a slightly higher risk during or immediately after bypass surgery. This may relate to the fact that women who undergo the surgery are generally older and in poorer health, and their smaller body size makes the surgery technically more difficult. However, the overall risks are relatively low when compared to the fact that many of these bypass operations significantly lengthen and improve the quality of the patient’s life. In some cases, the grafted arteries may also become blocked and require a second bypass surgery. Second bypass has slightly higher risks than the initial surgery, because patients are older and other, less optimal blood vessels must be used for the new grafts. However, bypassed arteries can remain functioning for many years, especially when the patient makes diet and exercise adjustments for cardiac health. Therefore, bypass surgery remains a popular choice for physicians treating severe coronary artery disease During coronary bypass surgery 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 conorary 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 occurred 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. After coronary bypass surgery After surgery, the patient is moved to a hospital bed in the cardiac surgical intensive care unit. Heart rate and blood pressure monitoring devices continuously monitor the patient for 12 to 24 hours. Family will be able to visit periodically. Medications that regulate circulation and blood pressure may be administered through the intravenous tube. A breathing tube (endotracheal tube) will remain in place until the physicians are confident that the patient is awake and ready to breathe comfortably without assistance. The patient may feel groggy and disoriented, and sites of incisions – both the chest and the leg, if a segment of blood vessel was taken from the leg – may be sore. Painkillers are given as necessary. Patients usually stay in the hospital at least three to five days and sometimes longer. During this time, tests will be conducted to assess and monitor the patient’s condition. After release from the hospital, the patient may experience side effects, such as: Loss of appetite Swelling in the area from which the segment of blood vessel was removed Difficulty sleeping Constipation Mood swings and feelings of depression Muscle pain or tightness in the shoulders and upper back Mild disorientation Some temporary memory loss Poor concentration Fatigue Many of these side effects usually disappear over the course of four to six weeks, although a full recovery may take a few months or more. When the patient is ready, he or she may be enrolled in a physician-supervised program of cardiac rehabilitation. This program teaches stress management techniques and other important lessons (e.g., about diet and exercise) and helps people to rebuild their strength and confidence. Potential risks with coronary bypass A successful surgery results in a dramatic increase in blood flow to the heart muscle. This increase in blood flow, in turn, reduces the pain, pressure or discomfort (angina) associated with cardiac ischemia. Abnormal heart rhythms (arrhythmias) may develop just after the surgery and may last three to four days, but these abnormal heart rhythms are usually only temporary. In addition, the chest and leg area where incisions were made will likely be slightly sore for at least a few weeks. However, severe pain should be reported to a physician. Complications that may arise from bypass surgery include: Bleeding Difficulty breathing Infection High blood pressure (hypertension) Abnormal heart rhythm (arrhythmia), particularly atrial fibrillation Most of these complications are short-term and are not serious, though advanced age and poor overall health may increase their risk and severity. More serious complications that may arise, usually due to the use of the heart-lung machine, include kidney failure, heart attack, stroke or even death. These risks are higher for older patients, people with diabetes and patients with other major health problems. However, it's also important to note that in recent years, the risk of serious complications due to cardiopulmonary bypass has been dramatically reduced due to improved surgical techniques. In one study, researchers found that the rate of serious complications fell by half in the period from the early 1980s to the mid 1990s. In addition, physicians have a number of tools at their disposal to further reduce the risk of post-operative complications. This includes the use of medications, such as aspirin and beta blockers, and very strict blood sugar control. One area of complication occurs when grafted arteries become blocked over time and a patient needs a second bypass surgery. This procedure presents greater risks for several reasons. The patient is older and their heart disease has usually worsened. The blood vessels used as grafts in the first surgery are not available to use for the second surgery. In addition, there may be adhesion around the original grafts that make the second surgery more difficult. Patients should discuss all additional risks with their physician