What Is  Coronary Artery Bypass Surgery

In  coronary artery bypass surgery -- also called  coronary artery bypass grafting, or CABG -- surgeons graft a healthy  artery or vein  to a diseased  coronary artery, beyond  the areas that are blocked by plaques.  This procedure allows blood to bypass the diseased part of  the artery, and improves  the supply of blood to the heart muscle. 

Who Should Get  Coronary Artery Bypass Surgery? 

Bypass surgery  is very effective  in improving symptoms of angina if you have unstable angina. If you have major  blockages in several coronary arteries,  or blockage in the left main  coronary artery (which is the most important  coronary artery), or a very weakened  heart muscle (a condition called cardiomyopathy, which you can read about here), bypass surgery can prolong your life when compared to treatment  with angioplasty and stenting, or with medical therapy alone. Bypass surgery can also be helpful in people with acute coronary syndrome. 

How is Bypass Surgery Performed? 

Bypass surgery is performed under general anesthesia.  The surgeon splits the breastbone  to open  the chest, then stops  the heart using chemicals or cold (called hypothermia) so that he/she can attach  the grafts without  the heart moving around. Blood circulation  is maintained, while  the heart  is stopped, using a cardiopulmonary bypass machine. Once  the grafts are attached the heart is started again. 

The grafts used during bypass surgery usually come from veins from  the legs (saphenous veins), or an artery from  the chest wall (the internal mammary artery). Grafts using  the artery often last longer than grafts using veins,  and the artery grafts do  not often develop stenosis, as vein grafts do. So internal mammary artery grafts should generally  be used whenever it  is feasible to do so (as determined  by the patient's anatomy).  It is fairly common for vein grafts to develop blockages due to atherosclerosis within 10 to 12 years of surgery. 

In recent years newer bypass surgery techniques are being developed called "minimally  invasive bypass surgery." These minimally invasive procedures involve smaller incisions, and they avoid having  to use the bypass machine. Unfortunately, minimally invasive bypass surgery  is only suitable for patients whose diseased arteries can be readily reached with this approach. 

What  are the Most Important Complications? 

Coronary  artery bypass surgery  is a major surgical procedure,  and patients often don't return to "normal"  for many weeks  or even months after surgery. It is common to experience poor appetite, weakness,  and pain over the incision for  a few weeks. Depression is seen in up to one of three patients after surgery, and unless  the depression  is recognized and treated, it can lead  to a greatly prolonged recovery time. 

Other possible complications after bypass surgery include myocardial infarction during or right after surgery (in less than 5% of patients), weakening of the heart muscle (which  is often temporary), arrhythmias (especially atrial fibrillation), pleural effusions (fluid accumulation between  the lung and the chest wall), infection of  the incision site, and a cognitive (thinking) disorder that has been termed "pump head" (after  the cardiopulmonary bypass "pump" that supports circulation during  the grafting procedure,  and that some have speculated is responsible for these cognitive changes). 

Because bypass surgery carries such serious risks, it is usually reserved for patients who are likely  to have their lives prolonged by  the surgery, or those whose symptoms  of angina persist despite aggressive attempts at medical treatment.