Plaque can build up inside arteries, block the normal flow of blood, and limit the amount of oxygen and nutrients that reach body tissues.
Surgical bypass can improve blood flow by creating a detour around the portion of an artery that is narrowed or blocked by plaque.
Surgical bypass is most commonly performed on arteries in the legs.
As people age, plaque made up of cholesterol and other fats (lipids), calcium, and fibrous scar tissue can accumulate on the inside walls of their arteries. Plaque deposits can enlarge, causing arteries to narrow and stiffen, a process called atherosclerosis or hardening of the arteries. This narrowing decreases blood flow and can result in insufficient oxygen levels in body tissue, known as ischemia. A small piece of loose plaque or a blood clot that lodges in a narrowed artery, called an arterial embolism, can also disrupt blood flow and cause ischemia.
Ischemia that results from narrowed or blocked arteries in the leg can cause pain in the feet and toes, skin ulcerations, and in extreme situations, numbness and muscle weakness. When the arteries that supply blood to a person's heart or brain become blocked and ischemia results, it can cause a heart attack or a stroke. To prevent these consequences, the physician may perform surgical bypass to reroute blood and improve blood flow around the blocked portion of an artery.
During surgical bypass, doctors make a new connection between arteries using a graft vessel, which is made from a portion of a person's own vein or a synthetic fabric tube. The graft vessel creates a detour, allowing blood to bypass any blockage.
Physicians most commonly perform bypasses in the legs. Surgical bypass for leg artery disease typically involves rerouting blood from the femoral artery in the thigh to another artery in the thigh, knee, lower leg, or foot.
Other arteries involved in surgical bypass may include:
The subclavian artery in the shoulder;
The vertebral arteries in the spine;
The iliac arteries, which are located in the pelvis; and
The renal (kidney) arteries.
WHEN IS THE PROCEDURE INDICATED?
Physicians first attempt to treat atherosclerotic artery disease by prescribing lifestyle changes, such as regular exercise, changes in diet, and control of risk factors such as smoking. Certain medications can also help prevent atherosclerosis from worsening.
However, surgery may be indicated if atherosclerosis progresses and does not respond to lifestyle changes or medication. For example, it may be needed to address severe leg artery disease, the complications of which include:
Claudication (leg discomfort caused by compromised circulation); and
Critical limb ischemia (blood flow prevents tissues from getting enough oxygen, resulting in pain, sores, or even loss of limb).
Before performing surgery, the physician determines the presence of risk factors, such as smoking, and listens to the patient describe symptoms. He or she also may order tests to assess the extent and exact location of any blockages, including:
Ankle/brachial index (compares the blood pressure in a person's arms to the blood pressure in the legs).
Contrast arteriography, also called angiography (injecting a contrast dye into the arteries and then taking x rays);
Duplex ultrasound; and
Magnetic resonance angiography (MRA);
WHAT TO EXPECT
Generally, before a bypass, the vascular surgeon selects the blood vessel graft that will connect the arteries. The most effective grafts for leg or arm bypasses are veins from a person's own body. The physician performing leg bypass surgery frequently chooses the great saphenous vein, the largest vein in the body, which runs between the foot and the groin. However, arteries made from synthetic fabrics may be used to bypass large arteries in the chest and abdomen.
To access the parts of the arteries that will be connected by the bypass, the physician makes incisions in the skin and muscle above the arteries. Next, the physician cuts into the wall of the diseased artery below the plaque blockage (known as arteriotomy). At this site (known as anastomosis), the physician attaches one end of the graft vessel with permanent sutures. The other end of the graft vessel is then routed through muscles, tendons, and other anatomy to a healthy artery, known as the inflow site. The physician sutures (sews) the inflow end of the graft to the wall of the healthy, inflow artery in the same manner.
The surgeon ensures that the bypass vessel is aligned correctly, so it will not kink, and checks for any signs of leakage. In some cases, the physician performs a completion arteriography to confirm the success of the procedure.
POST-PROCEDURE GUIDELINES AND CARE
Following the procedure, a person may stay in the hospital for 3 to 10 days, depending on how complicated the surgery. Many people who undergo surgical bypass need care from a visiting nurse, home health aide, or physical therapist immediately following discharge.
After discharge, it can take 5 weeks to 3 months to fully recover from surgery.
Surgical complications during bypass surgery vary depending upon which arteries are involved in the bypass and on a person's age and physical condition. Minor complications include swelling and infections at incision sites.
The risk for serious complications, such as a heart attack or stroke, is less than 2 percent.
After the bypass is complete, the physician predicts the graft vessel's patency, or the estimated time during which the bypass is expected to remain widely open and functioning properly. Grafts usually remain functional for 10 years or more. However, the patency period of a bypass graft can be shortened by factors including:
High blood pressure;
The length and diameter of the bypass graft; and
Infection or aneurysm of the blood vessel graft.
People who have undergone surgical bypass must visit their physician's office each year for an examination to make sure that the bypass graft remains patent.
People with bypass grafts should alter their lifestyles to help ensure the long-term success of the procedure. It is important to remember that surgical bypass does not reverse atherosclerosis. It only restores circulation to body tissues and reduces symptoms, such as claudication and leg ulcers. Changes that help lower blood cholesterol levels and may lower the risk of atherosclerotic disease include:
Eating foods low in fat, cholesterol and calories;
Exercising aerobically, such as brisk walking, for 20 to 30 minutes, five times a week;