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Arterial grafting is a surgical procedure performed to repair a blocked or damaged artery.

Arterial Grafting

Coronary artery bypass grafting (CABG) is a type of surgery that improves blood flow to the heart. Surgeons use CABG to treat people who have severe coronary artery disease (CAD). CAD is a disease in which a thick substance called plaque builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart.

Over time, plaque can harden or break open (rupture). Hardened plaque narrows the coronary arteries and reduces the flow of oxygen-rich blood to the heart. This can cause chest pain or discomfort called angina .

If the plaque ruptures, a blood clot can form on its surface. A large blood clot can mostly or completely block blood flow through a coronary artery. This is the most common cause of a heart attack. Over time, ruptured plaque also hardens and narrows the coronary arteries.

CABG is one treatment for CAD. During CABG, a healthy artery or vein from the body is connected, or grafted, to the blocked coronary artery. The grafted artery or vein bypasses (that is, goes around) the blocked portion of the coronary artery. This creates a new path for oxygen-rich blood to flow to the heart muscle.

Surgeons can bypass multiple coronary arteries during one surgery.

Coronary Artery Bypass Grafting

Overview

CABG is the most common type of heart surgery.Doctors called cardiothoracic surgeons do this surgery.

However, CABG isn't the only treatment for CAD. Other treatment options include lifestyle changes, medicines, and a procedure called stenting also known as coronary angioplasty.

PCI is a nonsurgical procedure that opens blocked or narrow coronary arteries. During PCI, a stent might be placed in a coronary artery to help keep it open. A stent is a small mesh tube that supports the inner artery wall.

CABG or PCI may be options if you have severe blockages in your large coronary arteries, especially if your heart's pumping action has already grown weak.

CABG also may be an option if you have blockages in the heart that can't be treated with angioplasty (stenting) In this situation, CABG may work better than other types of treatment.

The goals of CABG may include:

  • Improving your quality of life and reducing angina and other CAD symptoms
  • Allowing you to resume a more active lifestyle
  • Improving the pumping action of your heart if it has been damaged by a heart attack
  • Lowering the risk of a heart attack (in some patients, such as those who have diabetes)
  • Improving your chance of survival

Outlook

The results of CABG usually are excellent. The surgery improves or completely relieves angina symptoms in most patients. Although symptoms can recur, many people remain symptom-free for as long as 10 to 15 years. CABG also may lower your risk of having a heart attack and help you live longer.

You may need repeat investigations if blockages form in the grafted arteries or veins or in arteries that weren't blocked before. Taking medicines and making lifestyle changes as your doctor recommends can lower the risk of a graft becoming blocked.

Procedure

How is CABG surgery done?

The cardiac surgeon makes an incision down the middle of the chest and then saws through the breastbone (sternum). This procedure is called a median (middle) sternotomy (cutting of the sternum).

On pump CABG

The heart is cooled while a preservative solution is injected into the heart arteries. This process minimises damage caused by reduced blood flow during surgery and is referred to as "cardioplegia." Before bypass surgery can take place, a cardiopulmonary bypass must be established. Plastic tubes are placed in the right atrium to channel venous blood out of the body for passage through a plastic sheeting (membrane oxygenator) in the heart lung machine. The oxygenated blood is then returned to the body. The main aorta is clamped off (cross clamped) during CABG surgery to maintain a bloodless field and to allow bypasses to be connected to the aorta.

Off pump CABG (beating heart )

During bypass the heart is not stopped and bypass is done while the heart keeps on beating . The area where the bypass is done is controlled with stabiliser which allows to perform suturing . The beating heart surgery makes surgery less invasive and is advantages for better recovery .

This may significantly minimize the occasional memory defects and other complications that may be seen after CABG, and is a significant advance.

The most commonly used vessel for the bypass is the saphenous vein from the leg. Bypass grafting involves sewing the graft vessels to the coronary arteries beyond the narrowing or blockage. The other end of this vein is attached to the aorta. Chest wall arteries, particularly the left internal mammary artery, are now commonly used as bypass grafts.

This artery is separated from the chest wall and usually connected to the left anterior descending artery and/or one of its major branches beyond the blockage. The major advantage of using internal mammary arteries is that they tend to remain open longer than venous grafts. Ten years after CABG surgery, only 66% of vein grafts are open compared to 90% of internal mammary arteries. However, artery grafts are of limited length, and can only be used to bypass diseases located near the beginning (proximal) of the coronary arteries. Using internal mammary arteries may prolong CABG surgery because of the extra time needed to separate them from the chest wall. Therefore, internal mammary arteries may not be used for emergency CABG surgery when time is critical to restore coronary artery blood flow.

CABG surgery takes about four hours to complete. The use of 3 (triple), 4 (quadruple), or 5 (quintuple) bypasses are now routine. At the end of surgery, the sternum is wired together with stainless steel and the chest incision is sewn closed. Plastic tubes (chest tubes) are left in place to allow drainage of any remaining blood from the space around the heart (mediastinum). About 5% of patients require exploration within the first 24 hours because of continued bleeding after surgery. Chest tubes are usually removed the day after surgery. The breathing tube is usually removed shortly after surgery. Patients usually get out of bed and are transferred out of intensive care the day after surgery. Up to 25% of patients develop heart rhythm disturbances within the first three or four days after CABG surgery. These rhythm disturbances are usually temporary atrial fibrillation, and are felt to be related to surgical trauma to the heart. Most of these arrhythmias respond to standard medical therapy that can be weaned one month after surgery. The average length of stay in the hospital for CABG surgery has been reduced from as long as a week to only five to seven days in most patients. Many young patients can even be discharged home after four days.

How do patients recover after CABG surgery?

Sutures are removed from the chest prior to discharge and from the leg (if the saphenous vein is used) after 7 to 10 days. Even though smaller leg veins will take over the role of the saphenous vein, a certain degree of swelling (edema) in the affected ankle is common.. This swelling usually resolves after about six to eight weeks. Healing of the breastbone takes about six weeks and is the primary limitation in recovering from CABG surgery. Patients are advised not to lift anything more than 10 kgs or perform heavy exertion during this healing period. They are also advised not to drive for the first four weeks to avoid any injury to the chest. Patients can return to normal sexual activity as long as they minimise positions that put significant weight on the chest or upper arms. Return to work usually occurs after the six week recovery, but may be much sooner for non-strenuous employment.

Rehabilitation consists of a 12 week program of gradually increasing monitored exercise lasting one hour three times a week. Patients are also counselled about the importance of lifestyle changes to lower their chance of developing further CAD. These include stopping smoking, reducing weight and dietary fat, controlling blood pressure and diabetes, and lowering blood cholesterol levels.

Exercise stress testing is routinely done one year after CABG surgery.

What are the risks and complications?

Overall mortality related to CABG is 3-4%. During and shortly after CABG surgery, heart attacks occur in 5 to 10% of patients and are the main cause of death. About 5% of patients require exploration because of bleeding. This second surgery increases the risk of chest infection and lung complications. Stroke occurs in 1-2%, primarily in elderly patients.

Mortality and complications increase with.

  • age (older than 70 years),
  • poor heart muscle function,
  • disease obstructing the left main coronary artery,
  • diabetes,
  • chronic lung disease, and
  • Chronic kidney failure

Mortality may be higher in women, primarily due to their advanced age at the time of CABG surgery and smaller coronary arteries. Women develop coronary artery disease about 10 years later than men because of hormonal "protection" while they still regularly menstruate (although in women with risk factors for coronary artery disease, especially smoking, elevated lipids, and diabetes, the possibility for the development of coronary artery disease at a young age is very real). Women are generally of smaller stature than men, with smaller coronary arteries. These small arteries make CABG surgery technically more difficult and prolonged. The smaller vessels also decrease both short and long-term graft function.

What are the risks and complications of CABG surgery?

A very small percentage of vein grafts may become blocked within the first two weeks after CABG surgery due to blood clotting. Blood clots form in the grafts usually because of small arteries beyond the insertion site of the graft causing sluggish blood run off. Another 10% of vein grafts close off between two weeks and one year after CABG surgery. Use of aspirin to thin the blood has been shown to reduce these later closings by 50%. Grafts become narrowed after the first five years as cells stick to the inner lining and multiply, causing formation of scar tissue (intimal fibrosis) and actual atherosclerosis. After 10 years, only 2/3 of vein grafts are open and 1/2 of these have at least moderate narrowing. Internal mammary grafts have a much higher (90%) 10 year rate of remaining open. This difference in longevity has caused a shift in surgical practices toward greater use of internal mammary and other arteries as opposed to veins for bypasses.

It has been shown that in CABG patients with elevated LDL cholesterol (bad cholesterol) levels, use of cholesterol-lowering medications (particularly the statin family of drugs) to lower LDL levels will significantly improve long-term graft patency as well as improve survival benefit and heart attack risk. Patients are also advised about the importance of lifestyle changes to lower their chance of developing further atherosclerosis in their coronary arteries. These include stopping smoking, exercise, reducing weight and dietary fat, as well as controlling blood pressure and diabetes. Frequent monitoring of CABG patients with physiologic testing can identify early problems in grafts. PTCA (angioplasty) with stenting, in addition to aggressive risk factor modification, may significantly limit the need for repeat CABG years later. Repeat CABG surgery is occasionally necessary, but may have a higher risk of complication.

How do CABG surgery and angioplasty (PTCA) compare?

Ongoing studies are comparing the treatment results of angioplasty (PTCA) versus bypass (CABG surgery) in patients who are candidates for either procedure. Both procedures are very effective in reducing angina symptoms, preventing heart attacks, and reducing death. Many studies have either shown similar benefits or slight advantage to CABG (primarily in severe diabetics and patients having multiple blockages). The best choice for an individual patient is best made by their cardiologist, surgeon, and primary doctor.

Total arterial bypass

Internal mammary grafts have a much higher (90%) 10 year rate of remaining open. This difference in longevity has caused a shift in surgical practices toward greater use of internal mammary and other arteries as opposed to veins for bypasses.As chances of arterial graft Woking for longer time are far more then venous grafts a shift in technique of bypass is important. A highly specialised technique where in both internal mammary arteries are used for bypass grafting has evolved .We are routinely using both internal mammary arteries for bypass grafting in almost all patients .both internal Mammary arteries are harvested and all blocked arteries are bypassed with composite graft using right and left internal mammary arteries . This technique is technically challenging and increases operation time by just twenty minutes but prolongs survival . These arteries are very close to natural arteries of heart so are at lesser chance of blockage even at 25 years after surgery . The recovery is faster as there is other cut except one on chest . Another advantage is less risk of neurological complications with this technique as aorta is not touched (a aortic ).We strongly advocate this technique of bypass .