Peripheral Vascular Bypass Surgery

Definition
Purpose
Demographics
Description
Diagnosis/Preparation
Aftercare
Risks
Normal results
Morbidity and mortality rates
Alternatives

Definition

A peripheral vascular bypass, also called a lower extremity bypass, is the surgical rerouting of blood flow around an obstructed artery that supplies blood to the legs and feet. This surgery is performed when the build-up of fatty deposits (plaque) in an artery has blocked the normal flow of blood that carries oxygen and nutrients to the lower extremities. Bypass surgery reroutes blood from above the obstructed portion of an artery to another vessel below the obstruction.

A bypass surgery is named for the artery that will be bypassed and the arteries that will receive the rerouted blood. The three common peripheral vascular bypass surgeries are:

• Aortobifemoral bypass surgery, which reroutes blood from the abdominal aorta to the two femoral arteries in the groin.
• Femoropopliteal bypass (fem-pop bypass) surgery, which reroutes blood from the femoral artery to the popliteal arteries above or below the knee.
• Femorotibial bypass surgery, which reroutes blood between the femoral artery and the tibial artery.

A substitute vessel or graft must be used in bypass surgeries to reroute the blood. The graft may be a healthy segment of the patient’s own saphenous vein (autogenous graft), a vein that runs the entire length of the thigh. A synthetic graft may be used if the patient’s saphenous vein is not healthy or long enough, or if the vessel to be bypassed is a larger artery that cannot be replaced by a smaller vein.

Purpose

Peripheral vascular bypass surgery is performed to restore blood flow (revascularization) in the veins and arteries of people who have peripheral arterial disease (PAD), a form of peripheral vascular disease (PVD). People with PAD develop widespread hardening and narrowing of the arteries (atherosclerosis) from the gradual build-up of plaque. In advanced PAD, plaque accumulations (atheromas) obstruct arteries in the lower abdomen, groin, and legs, blocking the flow of blood, oxygen, and nutrients to the lower extremities (legs and feet). Rerouting blood flow around the blockage is one way to restore circulation. It relieves symptoms in the legs and feet, and helps avoid serious consequences such as heart attack, stroke, limb amputation, or death.

Demographics

Approximately 8-8 million people in the United States have PAD caused by atherosclerosis. These people are at high risk of arterial occlusion, and are candidates for peripheral vascular bypass surgery. Occlusive arterial disease is found in 12-20% of men and women older than age 65. In people younger than age 70, it occurs more often in men than women, particularly in those who have ever smoked or who

KEY TERMS

Atheroma— An accumulation of plaque blocking a portion of an artery.

Atherosclerosis (arteriosclerosis)— Process of thickening and hardening of large- and medium-sized arteries as a result of fatty deposits on their inner linings.

Intermittent claudication— Pain that occurs on walking and is relieved on rest.

Ischemia— An inadequate blood supply (circulation) in a part of the body where arteries are blocked.

Peripheral arterial disease (PAD)— An occlusive disease of the arteries most often caused by progressive atherosclerosis.

Peripheral arteries— Arteries other than those of the heart and brain, especially those that supply the lower body organs and limbs.

Plaque— A collection of wax-like fatty deposits on the insides of artery walls.

Restenosis— The repeat narrowing of blood vessels that may occur after surgical removal of plaque when preventive measures are not taken.

Revascularization— Restoring normal blood flow (circulation) in the body’s vascular (veins and arteries) system.

Stenosis— Narrowing of a blood vessel.

have diabetes. Women with PAD live longer than men with the same condition, accounting for the equal incidence in older Americans. African-Americans are at greater risk for arterial occlusion than other racial groups in the United States.

Description

The circulatory system delivers blood, oxygen, and vital nutrients to the limbs, organs, and tissues throughout the body. This is accomplished via arteries that deliver oxygen-rich blood from the heart to the tissues and veins that return oxygen-poor blood from organs and tissues back to the heart and lungs for re-oxygenation. In PAD, the gradual accumulation of plaque in the inner lining (endothelium) of the artery walls results in widespread atherosclerosis that can occlude the arteries and reduce or cut off the supply of blood, oxygen, and nutrients to organ systems or limbs.

Peripheral vascular bypass surgery is a treatment option when PAD affects the legs and feet. PAD is similar to coronary artery disease (CAD), which leads to heart attacks and carotid artery disease (CAD), which causes stroke. Atherosclerosis causes each of these diseases. Most often, atherosclerotic blockage or narrowing (stenosis) occurs in the femoral arteries that supply the thighs with blood or in the common iliac arteries, which are branches of the lower abdominal aorta that also supplies the legs. The popliteal arteries (a portion of the femoral arteries near the surface of the legs) or the posterior tibial and peroneal arteries below the knee (portions of the popliteal artery) can be affected.

Just as coronary artery disease can cause a heart attack when plaque blocks the arteries of the heart, or blockage in the carotid artery leading to the brain can cause a stroke, occlusion of the peripheral arteries can create life-threatening conditions. Plaque accumulation in the peripheral arteries blocks the flow of oxygen-carrying blood, causing cells and tissue in the legs and feet to die from lack of oxygen (ischemia) and nutrition. Normal growth and cell repair cannot take place, which can lead to gangrene in the limbs and subsequent amputation. If pieces of the plaque break off, they can travel from the legs to the heart or brain, causing heart attack, stroke, or death.

The development of atherosclerosis and PAD is influenced by heredity and also by lifestyle factors, such as dietary habits and levels of exercise. The risk factors for atherosclerosis include:

• high levels of blood cholesterol and triglycerides.
• high blood pressure (hypertension)
• cigarette smoking or exposure to tobacco smoke
• diabetes, types 1 and 2
• obesity
• inactivity, lack of exercise
• family history of early cardiovascular disease

Sometimes the body will attempt to change the flow of blood when a portion of an artery is narrowed by plaque. Smaller arteries around the blockage begin to take over some of the blood flow. This adaptation of the body (collateral circulation) is one reason for the absence of symptoms in some people who have PAD. Another reason is that plaque develops gradually as people age. Symptoms usually don’t occur until a blockage is over 70%, or when a piece of plaque breaks off and blocks an artery completely. Blockage in the legs reduces or cuts off circulation, causing painful cramping during walking, which is relieved on rest (intermittent claudication). The feet may ache even when lying down at night.

When narrowing of an artery occurs gradually, symptoms are not as severe as they are when sudden, complete blockage occurs. Sudden blockage does not allow time for collateral vessels to develop, and symptoms can be severe. Gradual blockage creates muscle aches and pain, cramping, and sensations of fatigue or numbness in the limbs; sudden blockage may cause severe pain, coldness, and numbness. At times, no pulse can be felt, a leg may become blue (cyanotic) from lack of oxygen, or paralysis may occur.

When the lower aorta, femoral artery, and common iliac arteries (all in the lower abdominal and groin areas) are blocked, gradual narrowing may produce cramping pain and numbness in the buttocks and thighs, and men may become impotent. Sudden blockage will cause both legs to become painful, pale, cold, and numb, with no pulse. The feet may become painful, infected, or even gangrenous when gradual or complete blockage limits or cuts off circulation. Feet may become purple or red, a condition called rubor that indicates severe narrowing. Pain in the feet or legs during rest is viewed as an indication for bypass surgery because circulation is reduced to a degree that threatens survival of the limb.

Early treatment for PAD usually includes medical intervention to reduce the causes of atherosclerosis, such as lowering cholesterol and blood pressure, smoking cessation, and reducing the likelihood of clot formation. When these measures are not effective, or an artery becomes completely blocked, lower extremity bypass surgery may be performed to restore circulation, reduce foot and leg symptoms, and prevent limb amputation.

Bypass surgery is an open procedure that requires general anesthesia . In femoropopliteal bypass or femorotibial bypass, the surgeon makes an incision in the groin and thigh to expose the affected artery above the blockage, and another incision (behind the knee for the popliteal artery, for example) to expose the artery below the blockage. The arteries are blocked off with vascular clamps. If an autogenous graft is used, the surgeon passes a dissected (cut and removed) segment of the saphenous vein along the artery that is being bypassed. If the saphenous vein is not long enough or is not of good quality, a tubular graft of synthetic (prosthetic) material is used. The surgeon sutures the graft into an opening in the side of one artery and then into the side of the other. In a femoropopliteal bypass, for example, the graft extends from the femoral artery to the popliteal artery. The clamps are then removed and the flow of blood is observed to make sure it bypasses the blocked portion of the affected artery.

Aortobifemoral bypass surgery is conducted in much the same way, although it requires an abdominal incision to access the lower portion of the abdominal aorta and both femoral arteries in the groin. This is generally a longer and more difficult procedure. Synthetic grafts are used because the lower abdominal aorta is a large conduit, and its blood flow cannot be handled by the smaller saphenous vein. Vascular surgeons prefer the saphenous vein graft for femoropopliteal or femorotibial bypass surgery because it has proven to stay open and provide better performance for a longer period of time than synthetic grafts. Bypass surgery patients will be given heparin, a blood thinner, immediately after the surgery to prevent clotting in the new bypass graft.

Diagnosis/Preparation

Diagnosis

After obtaining a detailed history and reviewing symptoms, the physician examines the legs and feet, and orders appropriate tests or procedures to evaluate the vascular system. Diagnostic tests and procedures may include:

• Blood pressure and pulses—pressure measurements are taken in the arms and legs. Pulses are measured in the arms, armpits, wrists, groin, ankles, and behind the knees to determine where blockages may exist, since no pulse is usually felt below a blockage.
• Doppler ultrasonography—direct measurement of blood flow and rates of flow, sometimes performed in conjunction with stress testing (tests that incorporate an exercise component).
• Angiography—an x-ray procedure that provides clear images of the affected arteries before surgery is performed.
• Blood tests—routine tests such as cholesterol and glucose, as well as tests to help identify other causes of narrowed arteries, such as inflammation, thoracic outlet syndrome, high homocycteine levels, or arteritis.
• Spiral computed tomography (CT angiography) or magnetic resonance angiography (MRA)—less invasive forms of angiography.

Preparation

If not done earlier in the diagnostic process, ultra-sonography or angiography procedures may be performed when the patient is admitted to the hospital. These tests help the physician evaluate the amount of plaque and exact location of the narrowing or obstruction. Any underlying medical condition, such as high blood pressure, heart disease, or diabetes is treated prior to bypass surgery to help obtain the best surgical result. Regular medications, such as blood pressure drugs or diuretics, may be discontinued in some patients. Routine pre-operative blood and urine tests are performed when the patient is admitted to the hospital.

Aftercare

After bypass surgery, the patient is moved to a recovery area where blood pressure, temperature, and heart rate are monitored for an hour or more. The surgical site is checked regularly. The patient is then transferred to a concentrated care unit to be observed for any signs of complications. The total hospital stay for femoropopliteal bypass or femorotibial bypass surgery may be two to four days. Recovery is slower with aortobifemoral bypass surgery, which involves abdominal incisions, and the hospital stay may extend up to a week. Walking will begin immediately for patients who have had femoropopliteal or femorotibial bypasses, but patients who have had aortobife-moral bypass may be kept in bed for 48 hours. When bypass patients go home, walking more each day, as tolerated, is encouraged to help maintain blood flow and muscle strength. Feet and legs can be elevated on a footstool or pillow when the patient rests. Some swelling of the leg should be expected; it does not indicate a problem and will resolve within a month or two.

During recuperation, the patient may be given pain medication if needed, and clot prevention (anticoagulant) medication. Any redness of the surgical site or other signs of infection will be treated with antibiotics. Patients are advised to reduce the risk factors for atherosclerosis in order to avoid repeat narrowing or blockage of the arteries. Repeat stenosis (restenosis) has been shown to occur frequently in people who do not make the necessary lifestyle modifications, such as changes in diet, exercise, and smoking cessation. The benefits of the bypass surgery may only be temporary if underlying disease, such as atherosclerosis, high blood pressure, or diabetes, is not also treated.

Risks

The risks associated with peripheral vascular bypass surgery are related to the progressive atherosclerosis that led to arterial occlusion, including a return of pre-operative symptoms. In patients with advanced PAD, heart attack or heart failure may occur. Build up of plaque has also taken place in the

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

Peripheral vascular bypass surgery is performed by a vascular surgeon in a hospital operating room.

patient’s arteries of the heart. Restenosis, the continuing build up of plaque, can occur within months to years after surgery if risk factors are not controlled. Other complications may include:

• clot formation in a saphenous vein graft
• failed grafts or blockages in grafts
• reactions to anesthesia
• breathing difficulties
• embolism (clot from the surgical site traveling to vessels in the heart, lungs, or brain)
• changes in blood pressure
• infection of the surgical wound
• nerve injury (including sexual function impairment after aortobifemoral bypass)
• postoperative bleeding
• failure to heal properly

Normal results

A femoropopliteal or femorotibial bypass with anautogenous graft of good quality saphenous vein has been shown to have a 60-70% chance of staying open and functioning well for five to 10 years. Aortobife-moral bypass grafts have been shown to stay open and reduce symptoms in 80% of patients for up to 10 years. Pain and walking difficulties should be relieved after bypass surgery. Success rates improve when the underlying causes of atherosclerosis are monitored and managed effectively.

Morbidity and mortality rates

The risk of death or heart attack is about 3-5% in all patients undergoing peripheral vascular bypass surgery. Following bypass surgery, amputation is still an outcome in about 40% of all surgeries performed, usually due to progressive atherosclerosis or complications caused by the patient’s underlying disease condition.

QUESTIONS TO ASK THE DOCTOR

• Why is this surgery necessary?
• How will the surgery improve my condition?
• What kind of anesthesia will be given?
• How many of these procedures has the surgeon performed?
• How many surgical patients had complications after the procedure?
• How can the patient expect to feel after surgery?
• How soon will the patient be able to walk?
• How long will it take to recover completely?
• What are the chances of this problem recurring after surgery?
• What can be done to help prevent this problem from developing again?

Alternatives

Peripheral vascular bypass surgery is a mechanical way to reroute blood, and there is no alternative method. Alternative ways to prevent plaque build-up and reduce the risk of narrowing or blocking the peripheral arteries include nutritional supplements and alternative therapies, such as:

• Folic acid can help lower homocysteine levels and increase the oxygen-carrying capacity of red blood cells.
• Vitamins B₆ and B₁₂ help lower homocysteine levels.
• Antioxidant vitamins C and E work together to promote healthy blood vessels and improve circulation.
• Angelica, an herb that contains Coumadin, a recognized anticoagulant, which may help prevent clot formation in the blood.
• Essential fatty acids, as found in flax seed and other oils, to help reduce blood pressure and cholesterol, and maintain blood vessel elasticity.
• Chelation therapy, used to break up plaque and improve circulation.

Resources

BOOKS

Khatri, VP and JA Asensio. Operative Surgery Manual. 1st ed. Philadelphia: Saunders, 2003.

Libby, P. et al. Braunwald’s Heart Disease. 8th ed. Philadelphia: Saunders, 2007.

Townsend, CM et al. Sabiston Textbook of Surgery. 17th ed. Philadelphia: Saunders, 2004.

PERIODICALS

Perera GB. “Current trends in lower extremity revascularization.” Surgical Clinics of North America 87, no.5 (2007): 1135–1147.

Raffetto JD. “Differences in risk factors for lower extremity arterial occlusive disease.” Journal of the American College of Surgery 201, no.6 (2005): 1135–1147.

ORGANIZATIONS

American Heart Association (AHA). 7272 Greenville Ave., Dallas, TX 75231. (800) 242-8721. www.americanheart.org.

Vascular Disease Foundation. 3333 South Wadsworth Blvd. B104-37, Lakewood, CO 80227. (303) 949-8337 or (866)PADINFO (723-4636). www.vdf.org.

OTHER

Bypass Surgery for Peripheral Arterial Disease. Patient Information, Vascular Disease Foundation, 2003. www.vdf.org.

Hirsch, M.D., Alan T. “Occlusive Peripheral Arterial Disease.” The Merck Manual of Medicine—Home Edition, Heart and Blood Vessel Disorders 34:3. www.merck.com/pubs.

L. Lee Culvert

Peritoneal dialysis seeKidney dialysis

Peritoneal fluid analysis seeParacentesis

Vascular surgery

Definition

Vascular surgery is the treatment of surgery on diagnosed patients with diseases of the arterial, venous, and lymphatic systems (excluding the intracranial and coronary arteries).

Purpose

Vascular surgery is indicated when a patient has vascular disease that cannot be treated by less invasive, nonsurgical treatments. The purpose of vascular surgery is to treat vascular diseases, which are diseases of the arteries and veins. Arterial disease is a condition in which blood clots, arteriosclerosis, and other vascular conditions occur in the arteries. Venous disease involves problems that occur in the veins. Some vascular conditions occur only in arteries, others occur only in the veins, and some affect both veins and arteries.

Demographics

As people age, vascular diseases are very common. Since they rarely cause symptoms in the early stages, many people do not realize that they suffer from these diseases. Of the eight million people in the United States who may have peripheral vascular disease (PVD), a large percentage are males. In the majority of cases, the blockage is caused by one or more blood clots that travel to the lungs from another part of the body. Factors that increase the chances of vascular disease include:

• increasing age (which results in a loss of elasticity in the veins and their valves)
• a family history of heart or vascular disease
• illness or injury
• pregnancy
• prolonged periods of inactivity sitting, standing, or bed rest
• smoking
• obesity
• hypertension, diabetes, high cholesterol, or other conditions that affect the health of the cardiovascular system
• lack of exercise

Description

Vascular surgery involves techniques relating to endovascular surgeries including: balloon angioplasty and/or stenting, aortic and peripheral vascular endovascular stent/graft placement, thrombolysis, and other adjuncts for vascular reconstruction.

The vascular system is the network of blood vessels that circulate blood to and from the heart and lungs. The circulatory system (made up of the heart, arteries, veins, capillaries, and the circulating blood) provides nourishment to the body's cells and removes their waste. The arteries carry oxygenated blood from the heart to the cells. The veins return the blood from the cells back to the lungs for reoxygenation and recirculation by the heart. The aorta is the largest artery leaving the heart; it then subdivides into smaller arteries going to every part of the body. The arteries, as they narrow, are connected to smaller vessels called capillaries. In these capillaries, oxygen and nutrients are released from the blood into the cells, and cellular wastes are collected for the return trip. The capillaries then connect to veins, which return the blood back to the heart.

The aorta stems from the heart, arches upward, and then continues down through the chest (thorax) and the abdomen. The iliac arteries, which branch out from the aorta, provide blood to the pelvis and legs. The thoracic section of the aorta supplies blood to the upper body, as it continues through the chest. The abdominal section of the aorta, which supplies blood to the lower body, continues through the abdomen.

Vascular diseases are usually caused by conditions that clog or weaken blood vessels, or damage valves that control the flow of blood in and out of the veins, thus robbing them of vital blood nutrients and oxygen. A few common diseases affecting the arteries are peripheral vascular disease (PVD), carotid artery disease, and aortic aneurysms (AAA).

Surgery is used to treat specific diseased arteries, such as atherosclerosis, to help prevent strokes or heart attacks, improve or relieve angina or hypertension, remove aneurysms, improve claudication, and save legs that would otherwise have to be amputated. The choices involve repairing the artery, bypassing it, or replacing it.

As people age, atherosclerosis, commonly called hardening of the arteries, occurs with the constant passage of blood through the arteries. It can take on a number of forms, of which atherosclerosis (hardening of the innermost portion) is the most common. This occurs when fatty material containing cholesterol or calcium (plaque) is deposited on the innermost layer of the artery. This causes a narrowing of the inside diameter of the blood vessel. Eventually, the artery becomes so narrow that a blood clot (thrombus) forms, and blocks blood flow to an entire portion of the body. This condition is called PVD or peripheral arterial disease. In another form of atherosclerosis, a rough area or ulcer forms in the diseased interior of the artery. Blood clots then tend to develop on this ulcer, break off, and travel further along, forming a blockage where the arteries get narrower. A blockage resulting from a clot formed elsewhere in the body is called an embolism.

People who have few areas affected by PVD may be treated with angioplasty by opening up the blood vessel with a balloon placed on the end of a catheter. A stent is often used with angioplasty to help keep the artery open. The type of surgery used to treat PVD is based upon the size and location of the damaged artery. The following are surgery techniques used for severe PVD:

• Bypass surgery is preferred for people who have many areas of blockage or a long, continuous blockage.
• Aortobifemoral bypass is used for PVD affecting the major abdominal artery (aorta) and the large arteries that branch off of it.
• In a technique called thromboendarterectomy, the inner diseased layers of the artery are removed, leaving the relatively normal outer coats of the artery.
• Resection involves a technique to remove a diseased artery following an aneurysm; a bypass is created with a synthetic graft.
• In a bypass graft, a vein graft from another part of the body or a graft made from artificial material is used to create a detour around a blocked artery.
• Tibioperoneal bypass is used for PVD affecting the arteries in the lower leg or foot.
• Femoropopliteal (fem-pop) bypass surgery is used for PVD affecting the arteries above and below the knee.
• Embolectomy is a technique in which an embolic clot on the wall of the artery is removed, using an inflatable balloon catheter.
• Thrombectomy is a technique in which a balloon catheter is inserted into the affected artery beyond a blood clot. The balloon is then inflated and pulled back, bringing the clot with it.

An aneurysm occurs when weakened blood vessels bulge like balloons as blood flows through them. Once they have grown to a certain size, there is a risk of rupture and life-threatening bleeding. There are two types of aortic aneurysms: abdominal aortic aneurysm (AAA) and thoracic aortic aneurysm. This classification is based on where the aneurysm occurs along the aorta. Aneurysms are more common in the abdominal section of the aorta than the thoracic section.

Most blood clots originate in the legs, but they can also form in the veins of arms, the right side of the heart, or even at the tip of a catheter placed in a vein. The following venous disease conditions usually occur in the veins of the legs:

• varicose veins
• phlebitis
• venous stasis disease
• deep vein thrombosis (DVT)
• claudication
• blood clots

Carotid artery disease is a condition in which the arteries in the neck that supply blood to the brain become clogged; this condition can cause a stroke.

Lymphatic obstruction involves blockage of the lymph vessels, which drain fluid from tissues throughout the body and allow immune cells to travel where they are needed. Some of the causes of lymphatic obstruction (also known as swelling of the lymph passages), include infections such as chronic cellulitis, or parasitic infections such as filariasis, trauma, tumors, certain surgeries including mastectomy, and radiation therapy. There are rare forms of congenital lymphedema that probably result from abnormalities in the development of the lymphatic vessels. Most patients with lymphedema will not need surgery, as the symptoms are usually managed by other techniques. Surgical therapy for lymphedema includes removal of tissue containing abnormal lymphatics, and less commonly, transplant of tissue from areas with normal lymphatic tissues to areas with abnormal lymphatic drainage. In rare cases, bypass of abnormal lymphatic tissue is attempted, sometimes using vein grafts.

Other examples of vascular surgery include:

• cerebral aneurysm
• acute arterial and graft occlusion
• carotid endarterectomy
• endovascular grafting
• vasculogenic erectile dysfunction
• renal artery aneurysm
• surgery on varicose veins
• lower extremity amputation

Diagnosis/Preparation

In order for a patient to be diagnosed with a vascular disease, they must be clinically evaluated by a vascular surgeon, which includes a history and physical examination . A vascular surgeon also treats vascular disorders by non-operative means, including drug therapy and risk factor management.

The symptoms produced by atherosclerosis, thrombosis, embolisms, or aneurysms depend on the particular artery affected. These conditions can sometimes cause pain, but often there are no symptoms at all.

A physician has many ways of feeling, hearing, measuring, and even seeing arterial blockages. Many arteries in the body can be felt or palpated. A doctor can feel for a pulse in an area he or she believes afflicted. Usually the more advanced the arteriosclerosis, the less pulse in a given area.

As the artery becomes blocked, it can cause a noise very much like water roaring over rocky rapids. Your physician can listen to this noise (bruit) directly, or can use special amplification systems to hear the noise.

There are other tests that can be done to determine if arterial blood flow is normal:

• ankle-brachial index (ABI) test
• arteriogram
• segmental pressure test
• ultrasound scan
• magnetic resonance imaging
• computed tomography scan
• angiography
• lymphangiography
• lymphoscintigraphy
• plethysmography
• duplex ultrasound scanning

There may be no symptoms of vascular disease caused by blood clots until the clot grows large enough to block the flow of blood through the vein. The following symptoms may then come on suddenly:

• pain
• sudden swelling in the affected limb
• reddish blue discoloration
• enlargement of the superficial veins
• skin that is warm to the touch

The physician will probably do an evaluation of all organ systems including the heart, lungs, circulatory system, kidneys, and the gastrointestinal system. The decision whether to have surgery or not is based on the outcome of these evaluations.

For high-risk patients undergoing vascular surgery, research has shown that taking oral beta-blockers one to two weeks before surgery and continuing for at least two weeks after the operation can significantly reduce the chance of dying or having a heart attack. Scientists suspect that the drug improves oxygen balance in the wall of the heart and stabilizes plaques in the arteries.

Aftercare

The length of time in intensive care and hospitalization will vary with each surgery, as will the recovery time, depending on numerous factors. Because surgery for an AAA is more serious, the patient can expect to be in intensive care for 24 hours, and in the hospital for five to 10 days, providing the patient was healthy and had a smooth operative and postoperative course. If there are complications, the hospital stay will likely increase. It may take as long as six months to fully recover from surgery for an AAA.

Living a "heart-healthy lifestyle" is the best way of preventing and controlling vascular disease: do not smoke; eat nutritious foods low in fat; exercise; maintain a healthy weight; and control risk factors such as high blood pressure, high cholesterol, diabetes, hypertension, and other factors that contribute to vascular disease.

Medications that may be used to treat PVD include:

• aspirin and other antiplatelet medications to treat leg pain
• statins to lower cholesterol levels
• medications to control high blood pressure
• medications to control diabetes
• anticoagulants are rarely, but not generally, used to treat PVD unless the person is at an increased risk for forming blood clots

Risks

All surgeries carry some risks. There is a risk of infection whenever incisions are required. Operations in the chest or those that involve major blood vessels carry a higher risk of complications. Patients who smoke, have high blood pressure, chronic lung or kidney disease, or other illnesses are at greater risk of complications during and after surgery. Other risks of vascular surgery include:

• bleeding
• failed or blocked grafts
• heart attack or stroke
• leg swelling if a leg vein is used
• people over 65 years are at greater risk for brain impairment after major surgery
• the more damaged the circulatory system is before surgery, the higher susceptibility to mental decline after vascular surgery
• impotence

The patient should discuss risks with their surgeon after careful review of the patient's medical history and a physical examination.

Normal results

The success rate for vascular surgery varies depending on a number of factors which may influence the decision on whether to have surgery or not, as well as the results.

The chance that an aneurysm will rupture generally increases with the size of the aneurysm; AAAs smaller than 1.6 in (4 cm) in diameter have up to a 2% risk of rupture while ones larger than 2 in (5 cm) in diameter have a 22% risk of rupture within two years.

Arterial bypass surgery and peripheral bypass surgery have very good success rates. Most of those who undergo AAA surgery recover well, except in the case of a rupture. Most patients who have a ruptured aortic aneurysm die. Surgery for an already ruptured aneurysm is not usually successful, due to excessive, rapid blood loss.

Surgical therapy for lymphedema has met with limited success, and requires significant experience and technical expertise.

Morbidity and mortality rates

Peripheral vascular disease affects 10 million people in the United States, including 5% of those over 50. Only a quarter of PVD sufferers are receiving treatment. More than five million people in the United States develop DVT each year. More than 600,000 Americans experience a pulmonary embolism every year. Of those, approximately 200,000 people die from the condition.

Alternatives

There a few alternatives to treating vascular disease, although extensive research has not been done. Acupuncture is used to aid in hypertension and chelation therapy is thought to stabilize the effects of vascular disease. The focus should be on maintaining a proper diet and being aware of a family history of vascular disease so as to catch it as early as possible.

Resources

books

Cameron, John L. Current Surgical Therapy. 7th ed. Philadelphia: Mosby, 2002.

Hoballah, Jamal J. Vascular Reconstructions: Anatomy, Exposures, and Techniques. Berlin: Springer Verlag, 2000.

periodicals

Abir, Farshad, Iannis Kakisis, and Bauer Sumpio. "Do Vascular Surgery Patients need a Cardiology Work-up? A Review of Pre-operative Cardiac Clearance Guidelines in Vascular Surgery." European Journal of Vascular and Endovascular Surgery 25, no. 2 (2003): 110–117.

Moore, Wesley S., M.D., G. Patrick Clagett, M.D., Frank J. Veith, M.D., Gregory L. Moneta, M.D., Marshall W. Webster, M.D. et al. "Guidelines for Hospital Privileges in Vascular Surgery: An Update by an Ad Hoc Committee of the American Association for Vascular Surgery and the Society for Vascular Surgery." Journal of Vascular Surgery 36, no. 6 (2002): 1276–1282.

organizations

American Board of Vascular Surgery (ABVS). 900 Cummings Center. #221-U Beverly, MA 01915. <http://aavs.vascularweb.org>.

The National Heart, Lung and Blood Institute. 6701 Rockledge Drive, P.O. Box 30105, Bethesda, MD 20824-0105. (301) 592-8573. E-mail: <[email protected]>, <http://www.nhlhi.nih.gov>.

National Institutes of Health (NIH), Department of Health and Human Services. 9000 Rockville Pike. Bethesda, MD 20892.

The Society for Vascular Surgery. 900 Cummings Center, #221-U Beverly, MA 01915. <http://svs.vascularweb.org>.

Society of Interventional Radiology. 10201 Lee Highway, Suite 500. Fairfax, VA. 22030. (800) 488-7284. E-mail: <[email protected]>,<http://www.sirweb.org/index.shtml>.

The U.S. Department of Health and Human Services. 200 Independence Avenue, S.W., Washington, D.C. 20201. (877) 696-6775.

Valley Baptist Heart and Vascular Institute. 2101 Pease Street, P.O. Drawer 2588. Harlingen, TX 78550. (956) 389-4848.

other

Society of Interventional Radiology. Vascular Diseases. 2003 [cited May 29, 2003]. <http://www.sirweb.org/patPub/vascularTreatments.shtml>.

Crystal H. Kaczkowski, MSc

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

A vascular surgeon performs the procedure in a hospital operating room . Applicants for residency training in vascular surgery must have successfully completed a general surgery residency and be eligible for the board examination in general surgery. An individual must meet the standards set by the Vascular Surgery Board of the American Board of Surgery for cognitive knowledge and hypothetical case management. At the completion of a vascular surgery residency, both a written and oral examination must be completed before certification. A vascular surgeon is required to undergo periodic written reexamination.

QUESTIONS TO ASK THE DOCTOR

• Can my vascular disease be controlled with lifestyle changes?
• If a procedure is required, am I a candidate for a less invasive, interventional radiology treatment?
• What are the risks and benefits of this operation?
• What are the normal results of this operation?
• What happens if this operation does not go as planned?
• What is the expected recovery time?

Peripheral vascular bypass surgery

Definition

A peripheral vascular bypass, also called a lower extremity bypass, is the surgical rerouting of blood flow around an obstructed artery that supplies blood to the legs and feet. This surgery is performed when the buildup of fatty deposits (plaque) in an artery has blocked the normal flow of blood that carries oxygen and nutrients to the lower extremities. Bypass surgery reroutes blood from above the obstructed portion of an artery to another vessel below the obstruction.

A bypass surgery is named for the artery that will be bypassed and the arteries that will receive the rerouted blood. The three common peripheral vascular bypass surgeries are:

• Aortobifemoral bypass surgery, which reroutes blood from the abdominal aorta to the two femoral arteries in the groin.
• Femoropopliteal bypass (fem-pop bypass) surgery, which reroutes blood from the femoral artery to the popliteal arteries above or below the knee.
• Femorotibial bypass surgery, which reroutes blood between the femoral artery and the tibial artery.

A substitute vessel or graft must be used in bypass surgeries to reroute the blood. The graft may be a healthy segment of the patient's own saphenous vein (autogenous graft), a vein that runs the entire length of the thigh. A synthetic graft may be used if the patient's saphenous vein is not healthy or long enough, or if the vessel to be bypassed is a larger artery that cannot be replaced by a smaller vein.

Purpose

Peripheral vascular bypass surgery is performed to restore blood flow (revascularization) in the veins and arteries of people who have peripheral arterial disease (PAD), a form of peripheral vascular disease (PVD). People with PAD develop widespread hardening and narrowing of the arteries (atherosclerosis) from the gradual build-up of plaque. In advanced PAD, plaque accumulations (atheromas) obstruct arteries in the lower abdomen, groin, and legs, blocking the flow of blood, oxygen, and nutrients to the lower extremities (legs and feet). Rerouting blood flow around the blockage is one way to restore circulation. It relieves symptoms in the legs and feet, and helps avoid serious consequences such as heart attack, stroke, limb amputation , or death.

Demographics

Approximately 8–10 million people in the United States have PAD caused by atherosclerosis. These people are at high risk of arterial occlusion, and are candidates for peripheral vascular bypass surgery. Occlusive arterial disease is found in 15–20% of men and women older than age 70. In people younger than age 70, it occurs more often in men than women, particularly in those who have ever smoked or who have diabetes. Women with PAD live longer than men with the same condition, accounting for the equal incidence in older Americans. African-Americans are at greater risk for arterial occlusion than other racial groups in the United States.

Description

The circulatory system delivers blood, oxygen, and vital nutrients to the limbs, organs, and tissues throughout the body. This is accomplished via arteries that deliver oxygen-rich blood from the heart to the tissues and veins that return oxygen-poor blood from organs and tissues back to the heart and lungs for re-oxygenation. In PAD, the gradual accumulation of plaque in the inner lining (endothelium) of the artery walls results in widespread atherosclerosis that can occlude the arteries and reduce or cut off the supply of blood, oxygen, and nutrients to organ systems or limbs.

Peripheral vascular bypass surgery is a treatment option when PAD affects the legs and feet. PAD is similar to coronary artery disease (CAD), which leads to heart attacks and carotid artery disease (CAD), which causes stroke. Atherosclerosis causes each of these diseases. Most often, atherosclerotic blockage or narrowing (stenosis) occurs in the femoral arteries that supply the thighs with blood or in the common iliac arteries, which are branches of the lower abdominal aorta that also supplies the legs. The popliteal arteries (a portion of the femoral arteries near the surface of the legs) or the posterior tibial and peroneal arteries below the knee (portions of the popliteal artery) can be affected.

Just as coronary artery disease can cause a heart attack when plaque blocks the arteries of the heart, or blockage in the carotid artery leading to the brain can cause a stroke, occlusion of the peripheral arteries can create life-threatening conditions. Plaque accumulation in the peripheral arteries blocks the flow of oxygen-carrying blood, causing cells and tissue in the legs and feet to die from lack of oxygen (ischemia) and nutrition. Normal growth and cell repair cannot take place, which can lead to gangrene in the limbs and subsequent amputation. If pieces of the plaque break off, they can travel from the legs to the heart or brain, causing heart attack, stroke, or death.

The development of atherosclerosis and PAD is influenced by heredity and also by lifestyle factors, such as dietary habits and levels of exercise . The risk factors for atherosclerosis include:

• high levels of blood cholesterol and triglycerides.
• high blood pressure (hypertension)
• cigarette smoking or exposure to tobacco smoke
• diabetes, types 1 and 2
• obesity
• inactivity, lack of exercise
• family history of early cardiovascular disease

Sometimes the body will attempt to change the flow of blood when a portion of an artery is narrowed by plaque. Smaller arteries around the blockage begin to take over some of the blood flow. This adaptation of the body (collateral circulation) is one reason for the absence of symptoms in some people who have PAD. Another reason is that plaque develops gradually as people age. Symptoms usually don't occur until a blockage is over 70%, or when a piece of plaque breaks off and blocks an artery completely. Blockage in the legs reduces or cuts off circulation, causing painful cramping during walking, which is relieved on rest (intermittent claudication). The feet may ache even when lying down at night.

When narrowing of an artery occurs gradually, symptoms are not as severe as they are when sudden, complete blockage occurs. Sudden blockage does not allow time for collateral vessels to develop, and symptoms can be severe. Gradual blockage creates muscle aches and pain, cramping, and sensations of fatigue or numbness in the limbs; sudden blockage may cause severe pain, coldness, and numbness. At times, no pulse can be felt, a leg may become blue (cyanotic) from lack of oxygen, or paralysis may occur.

When the lower aorta, femoral artery, and common iliac arteries (all in the lower abdominal and groin areas) are blocked, gradual narrowing may produce cramping pain and numbness in the buttocks and thighs, and men may become impotent. Sudden blockage will cause both legs to become painful, pale, cold, and numb, with no pulse. The feet may become painful, infected, or even gangrenous when gradual or complete blockage limits or cuts off circulation. Feet may become purple or red, a condition called rubor that indicates severe narrowing. Pain in the feet or legs during rest is viewed as an indication for bypass surgery because circulation is reduced to a degree that threatens survival of the limb.

Early treatment for PAD usually includes medical intervention to reduce the causes of atherosclerosis, such as lowering cholesterol and blood pressure, smoking cessation , and reducing the likelihood of clot formation. When these measures are not effective, or an artery becomes completely blocked, lower extremity bypass surgery may be performed to restore circulation, reduce foot and leg symptoms, and prevent limb amputation.

Bypass surgery is an open procedure that requires general anesthesia. In femoropopliteal bypass or femorotibial bypass, the surgeon makes an incision in the groin and thigh to expose the affected artery above the blockage, and another incision (behind the knee for the popliteal artery, for example) to expose the artery below the blockage. The arteries are blocked off with vascular clamps. If an autogenous graft is used, the surgeon passes a dissected (cut and removed) segment of the saphenous vein along the artery that is being bypassed. If the saphenous vein is not long enough or is not of good quality, a tubular graft of synthetic (prosthetic) material is used. The surgeon sutures the graft into an opening in the side of one artery and then into the side of the other. In a femoropopliteal bypass, for example, the graft extends from the femoral artery to the popliteal artery. The clamps are then removed and the flow of blood is observed to make sure it bypasses the blocked portion of the affected artery.

Aortobifemoral bypass surgery is conducted in much the same way, although it requires an abdominal incision to access the lower portion of the abdominal aorta and both femoral arteries in the groin. This is generally a longer and more difficult procedure. Synthetic grafts are used because the lower abdominal aorta is a large conduit, and its blood flow cannot be handled by the smaller saphenous vein. Vascular surgeons prefer the saphenous vein graft for femoropopliteal or femorotibial bypass surgery because it has proven to stay open and provide better performance for a longer period of time than synthetic grafts. Bypass surgery patients will be given heparin, a blood thinner, immediately after the surgery to prevent clotting in the new bypass graft.

Diagnosis/Preparation

Diagnosis

After obtaining a detailed history and reviewing symptoms, the physician examines the legs and feet, and orders appropriate tests or procedures to evaluate the vascular system. Diagnostic tests and procedures may include:

• Blood pressure and pulses—pressure measurements are taken in the arms and legs. Pulses are measured in the arms, armpits, wrists, groin, ankles, and behind the knees to determine where blockages may exist, since no pulse is usually felt below a blockage.
• Doppler ultrasonography—direct measurement of blood flow and rates of flow, sometimes performed in conjunction with stress testing (tests that incorporate an exercise component).
• Angiography—an x ray procedure that provides clear images of the affected arteries before surgery is performed.
• Blood tests—routine tests such as cholesterol and glucose, as well as tests to help identify other causes of narrowed arteries, such as inflammation, thoracic outlet syndrome, high homocycteine levels, or arteritis.
• Spiral computed tomography (CT angiography ) or magnetic resonance angiography (MRA)—less invasive forms of angiography.

Preparation

If not done earlier in the diagnostic process, ultrasonography or angiography procedures may be performed when the patient is admitted to the hospital. These tests help the physician evaluate the amount of plaque and exact location of the narrowing or obstruction. Any underlying medical condition, such as high blood pressure, heart disease, or diabetes is treated prior to bypass surgery to help obtain the best surgical result. Regular medications, such as blood pressure drugs or diuretics , may be discontinued in some patients. Routine pre-operative blood and urine tests are performed when the patient is admitted to the hospital.

Aftercare

After bypass surgery, the patient is moved to a recovery area where blood pressure, temperature, and heart rate are monitored for an hour or more. The surgical site is checked regularly. The patient is then transferred to a concentrated care unit to be observed for any signs of complications. The total hospital stay for femoropopliteal bypass or femorotibial bypass surgery may be two to four days. Recovery is slower with aortobifemoral bypass surgery, which involves abdominal incisions, and the hospital stay may extend up to a week. Walking will begin immediately for patients who have had femoropopliteal or femorotibial bypasses, but patients who have had aortobifemoral bypass may be kept in bed for 48 hours. When bypass patients go home, walking more each day, as tolerated, is encouraged to help maintain blood flow and muscle strength. Feet and legs can be elevated on a footstool or pillow when the patient rests. Some swelling of the leg should be expected; it does not indicate a problem and will resolve within a month or two.

During recuperation, the patient may be given pain medication if needed, and clot prevention (anticoagulant) medication. Any redness of the surgical site or other signs of infection will be treated with antibiotics . Patients are advised to reduce the risk factors for atherosclerosis in order to avoid repeat narrowing or blockage of the arteries. Repeat stenosis (restenosis) has been shown to occur frequently in people who do not make the necessary lifestyle modifications, such as changes in diet, exercise, and smoking cessation. The benefits of the bypass surgery may only be temporary if underlying disease, such as atherosclerosis, high blood pressure, or diabetes, is not also treated.

Risks

The risks associated with peripheral vascular bypass surgery are related to the progressive atherosclerosis that led to arterial occlusion, including a return of pre-operative symptoms. In patients with advanced PAD, heart attack or heart failure may occur. Build up of plaque has also taken place in the patient's arteries of the heart. Restenosis, the continuing build up of plaque, can occur within months to years after surgery if risk factors are not controlled. Other complications may include:

• clot formation in a saphenous vein graft
• failed grafts or blockages in grafts
• reactions to anesthesia
• breathing difficulties
• embolism (clot from the surgical site traveling to vessels in the heart, lungs, or brain)
• changes in blood pressure
• infection of the surgical wound
• nerve injury (including sexual function impairment after aortobifemoral bypass)
• post-operative bleeding
• failure to heal properly

Normal results

A femoropopliteal or femorotibial bypass with an autogenous graft of good quality saphenous vein has been shown to have a 60–70% chance of staying open and functioning well for five to 10 years. Aortobifemoral bypass grafts have been shown to stay open and reduce symptoms in 80% of patients for up to 10 years. Pain and walking difficulties should be relieved after bypass surgery. Success rates improve when the underlying causes of atherosclerosis are monitored and managed effectively.

Morbidity and mortality rates

The risk of death or heart attack is about 3–5% in all patients undergoing peripheral vascular bypass surgery. Following bypass surgery, amputation is still an outcome in about 40% of all surgeries performed, usually due to progressive atherosclerosis or complications caused by the patient's underlying disease condition.

Alternatives

Peripheral vascular bypass surgery is a mechanical way to reroute blood, and there is no alternative method. Alternative ways to prevent plaque build-up and reduce the risk of narrowing or blocking the peripheral arteries include nutritional supplements and alternative therapies, such as:

• Folic acid can help lower homocysteine levels and increase the oxygen-carrying capacity of red blood cells.
• Vitamins B6 and B12 can help lower homocysteine levels.
• Antioxidant vitamins C and E work together to promote healthy blood vessels and improve circulation.
• Angelica, an herb that contains coumadin, a recognized anticoagulant, which may help prevent clot formation in the blood.
• Essential fatty acids, as found in flax seed and other oils, to help reduce blood pressure and cholesterol, and maintain blood vessel elasticity.
• Chelation therapy, used to break up plaque and improve circulation.

Resources

books

Cranton, Elmer M.D., ed. Bypassing Bypass Surgery: Chelation Therapy: A Non-Surgical Treatment for Reversing Arteriosclerosis, Improving Blocked Circulation, and Slowing the Aging Process. Hampton Roads Pub. Co., 2001.

McDougal, Gene. Unclog Your Arteries: How I Beat Atherosclerosis. 1st Books Library, 2001.

organizations

American Heart Association (AHA). 7272 Greenville Ave., Dallas, TX 75231. (800) 242-8721. <www.americanheart.org>.

Vascular Disease Foundation. 3333 South Wadsworth Blvd. B104-37, Lakewood, CO 80227. (303) 949-8337 or (866)PADINFO (723-4636). <www.vdf.org>.

other

Bypass Surgery for Peripheral Arterial Disease. Patient Information, Vascular Disease Foundation, 2003. <www.vdf.org.>

Hirsch, M.D., Alan T. "Occlusive Peripheral Arterial Disease." The Merck Manual of Medicine—Home Edition, Heart and Blood Vessel Disorders 34:3. <www.merck.com/pubs>.

L. Lee Culvert

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

Peripheral vascular bypass surgery is performed by a vascular surgeon in a hospital operating room .

QUESTIONS TO ASK THE DOCTOR

• Why is this surgery necessary?
• How will the surgery improve my condition?
• What kind of anesthesia will be given?
• How many of these procedures has the surgeon performed?
• How many surgical patients had complications after the procedure?
• How can the patient expect to feel after surgery?
• How soon will the patient be able to walk?
• How long will it take to recover completely?
• What are the chances of this problem recurring after surgery?
• What can be done to help prevent this problem from developing again?