Diseases

Atherosclerosis is a gradual process whereby hard cholesterol substances (plaques) are deposited in the walls of the arteries. This buildup of cholesterol plaques causes hardening of the artery walls and narrowing of the inner channel (lumen) of the artery. When this happens in the peripheral circulation, peripheral vascular disease is the result. The atherosclerosis process begins early in life (as early as teens in some people). When atherosclerosis is mild and the arteries are not substantially narrowed, atherosclerosis causes no symptoms. Therefore, many adults typically are unaware that their arteries are gradually accumulating cholesterol plaques. However, when atherosclerosis becomes advanced with aging, it can cause critical narrowing of the arteries resulting in tissue ischemia (lack of blood and oxygen).Arteries that are narrowed by advanced atherosclerosis can cause diseases in different organs. For example, advanced atherosclerosis of the coronary arteries (arteries that supply heart muscles) can lead to angina and heart attacks. Advanced atherosclerosis of the carotid and cerebral arteries (arteries that supply blood to the brain) can lead to strokes and transient ischemic attacks (TIAs). Advanced atherosclerosis in the lower extremities can lead to pain while walking or exercising (claudication), deficient wound healing, and/or leg ulcers.Picture of Carotid Artery Disease and Plaque BuildupPicture of a Heart Attack (Myocardial Infarction) - Buildup of Cholesterol Plaque and Blood ClotAtherosclerosis is often generalized, meaning it affects arteries throughout the body. Therefore, patients with heart attacks are also more likely to develop strokes and peripheral vascular disease, and vice versa.

Peripheral vascular disease related to atherosclerosis can be prevented by minimizing the risk factors that are controllable, such as eating a healthy diet, maintaining a healthy weight, not smoking, getting regular exercise, and maintaining good control of blood sugar levels if you have diabetes.

Atherosclerosis causes disease in two ways. 1) Atherosclerosis can limit the ability of the narrowed arteries to increase delivery of blood and oxygen to the to tissues of the body during times when oxygen demand needs to be increased, for example, during exertion; or 2) complete obstruction of an artery by a thrombus or embolus (thrombus and embolus are forms of blood clots), which results in tissue death (necrosis). Exertional angina and intermittent claudication are two examples of insufficient delivery of blood and oxygen to meet tissue demand; whereas strokes and heart attacks are examples of death of tissue caused by complete artery obstruction by blood clots.There are many similarities between coronary artery diseases (atherosclerosis involving the arteries of the heart) and peripheral artery disease, and the two conditions may coexist in the same individual. For example, patients with exertional angina typically have no symptoms at rest. However, during exertion the critically narrowed coronary arteries are incapable of increasing blood and oxygen delivery to meet the increased oxygen needs of the heart muscles. Lack of blood and oxygen causes chest pain (exertional angina). Exertional angina typically subsides when the patient rests. In patients with intermittent claudication, the narrowed arteries in the lower extremities (for example, a narrowed artery at the groin) cannot increase blood and oxygen delivery to the calf muscles during walking. These patients experience pain in the calf muscles that will only subside after resting.Patients with unstable angina have critically narrowed coronary arteries that cannot deliver enough blood and oxygen to the heart muscle even at rest. These patients have chest pain at rest and are at imminent risk of developing heart attacks. Patients with severe artery occlusion in the legs can develop rest pain (usually in the feet). Rest pain represents such severe occlusion that there is insufficient blood supply to the feet even at rest. They are at risk of developing foot ulcers and gangrene.When atherosclerosis narrows the arteries, blood tends to clot in the narrowed areas, forming a thrombus, a type of blood clot (plural thrombi). Sometimes pieces of the blood clot break off and travel in the bloodstream until they are trapped in a narrower point in the artery beyond in which they cannot pass. A thrombus or piece of thrombus that travels to another point is called an embolus. Thrombi and emboli can cause sudden and complete artery blockage, leading to tissue necrosis (death of tissue due to lack of oxygen).For example, complete blockage of a coronary artery by a thrombus causes heart attack, while complete blockage of a carotid or cerebral artery causes ischemic stroke. Emboli originating from atherosclerosis in the aorta (the main artery delivering blood to the body) can obstruct small arteries in the feet, resulting in painful and blue (cyanotic) toes, foot ulcers, and even gangrene.What are collateral vessels or collateral circulation?Sometimes, despite the presence of a severe blockage in an artery, the involved area does not become painful or lose its blood supply due to the presence of collateral vessels. Collateral circulation means that the particular area is supplied by more than one artery, so that that blockage of a single vessel does not result in a severe degree of blood loss. Collateral circulation can develop over time to help provide oxygenated blood to an area where an artery is narrowed. Doctors believe that regular supervised exercise can stimulate the growth and development of collateral circulation and relieve symptoms of intermittent claudication.

The doctor will perform a physical exam and look for signs and symptoms of peripheral artery disease, for example, weak or absent artery pulses in the extremities, bruits (sounds that can be heard through a stethoscope), blood pressure changes, and skin color and nail changesIn addition to the history of symptoms and the physical signs of peripheral artery disease imaging tests can be used in the diagnosis of the condition. Imaging tests include:

• Doppler ultrasound - This form of ultrasound (measurement of high-frequency sound waves that are reflected off of tissues) that can detect and measure blood flow. Doppler ultrasound is used to measure blood pressures behind the knees and at the ankles. In patients with significant peripheral artery disease in the legs, the blood pressures in the ankles will be lower than the blood pressure in the arms (brachial blood pressure). The ankle-brachial index (ABI) is a number derived from dividing the ankle blood pressure by the brachial blood pressure. An ABI of 0.9 to 1.3 is normal, an ABI less than 0.9 indicate the presence of peripheral artery disease in the arteries in the legs, and an ABI below 0.5 usually indicates severe arterial occlusion in the legs.
• Duplex ultrasound - This is a color assisted noninvasive technique to study the arteries. Ultrasound probes can be placed on the skin overlying the arteries and can accurately detect the site of artery stenosis as well as measure the degree of obstruction.
• Angiography - An angiography is an imaging procedure to study the blood vessels of the extremities, similar to the way a coronary angiogram provides an image of the blood vessels supplying the heart. It is the most accurate test to detect the location(s) and severity of artery occlusion, as well as collateral circulations. Small hollow plastic tubes (catheters) are advanced from a small skin puncture at the groin (or the arm), under X-ray guidance, to the aorta and the arteries. Iodine contrast "dye," is then injected into the arteries while an X-ray video is recorded. Angiogram gives the doctor a picture of the location and severity of narrowed artery segments. This information is important in helping the doctor select patients for angioplasty or surgical bypass (see below).
• Because X-ray angiography is invasive with potential side effects (such as injury to blood vessels and contrast dye reactions), it is not used for initial diagnosis of peripheral artery disease. It is only used when a patient with severe peripheral artery disease symptoms is considered for angioplasty or surgery. A number of different imaging methods have been used in angiography examinations, including X-rays, magnetic resonance imaging (MRI), and computed tomography (CT) scans.
• Magnetic resonance imaging (MRI) angiography uses magnetism, radio waves, and a computer to produce images of body structures and has the advantage of avoiding X-ray radiation exposure.

In rare cases, the decreased circulation to the extremities characteristic of peripheral artery disease can lead to open sores that do not heal, ulcers, gangrene, or other injuries to the extremities. The areas that do not receive adequate blood flow are also more prone to develop infections and, in extreme cases, amputation may be necessary.

Treatment goals for peripheral artery disease include:

1. Relieve the pain of intermittent claudication.
2. Improve exercise tolerance by increasing the walking distance before the onset of claudication.
3. Prevent critical artery occlusion that can lead to foot ulcers, gangrene, and amputation.
4. Prevent heart attacks and strokes.

Treatment of peripheral artery disease includes lifestyle measures, supervised exercises, medications, angioplasty, and surgery.Lifestyle changes

• Smoking cessation eliminates a major risk factor for disease progression, and it lowers the incidences of pain at rest and amputations. Smoking cessation also is important to prevent heart attacks and strokes.
• A healthy diet can help lower blood cholesterol and other lipid levels and may help control blood pressure.
• Keep other risk factors, such as diabetes, lipid levels, and blood pressure under control by following medical advice regarding medications and lifestyle changes.

Supervised exerciseProper exercise can condition the muscles to use oxygen effectively and can speed the development of collateral circulation. Clinical trials have shown that regular supervised exercise can reduce symptoms of intermittent claudication and allow individuals to walk longer before the onset of claudication. Ideally, your doctor should prescribe an exercise program tailored to your specific needs.Rehabilitation programs supervised by healthcare professionals such as nurses or physical therapists may help. Exercise at least three times a week, each session lasting longer than 30 to 45 minutes for the best results. Exercise usually involves walking on a monitored treadmill until claudication develops; walking time is then gradually increased with each session. Patients are also monitored for the development of chest pain or heart rhythm irregularities during exercise.

A number of conditions such as vasculitis may cause damage to blood vessels throughout the body. Injuries to blood vessels (from accidents such as auto accidents or sports injuries), blood-clotting disorders, and damage to blood vessels during surgery can also lead to inadequate blood supply to body tissues (ischemia).Tissue ischemia can also occur in the absence of atherosclerosis or other abnormalities of arteries. One example of a condition in which the blood vessels themselves are not damaged is Raynaud's disease, which is believed to occur due to spasms in blood vessels brought on by stress or a cold environment.Since atherosclerosis of the peripheral arteries (PAD) is by far the most common cause of peripheral vascular disease, the rest of this article focuses upon peripheral artery disease.

Approximately half of people with peripheral artery disease do not experience any symptoms. For patients with symptoms, the most common symptoms are intermittent claudication and rest pain.

• Intermittent claudication refers to arm or leg pain or cramping in the arms or legs that occurs with exercise and goes away with rest. The severity and location of the pain of intermittent claudication vary depending upon the location and extent of blockage of the involved artery. The most common location of intermittent claudication is the calf muscle of the leg, leading to calf or leg pain while walking. The pain in the calf muscle occurs only during exercise such as walking, and the pain steadily increases with continued walking until the patient has to stop due to intolerable pain. Then the pain quickly subsides during rest. Intermittent claudication can affect one or both legs.
• Rest pain in the legs occurs when the artery occlusion is so critical that there is not enough blood and oxygen supply to the legs even at rest and represents a more serious form of the condition. The pain typically affects the feet, is usually severe, and occurs at night when the patient is lying down, face up.

Other symptoms and signs of peripheral artery disease include:

• Numbness of the legs or feet
• Weakness and atrophy (diminished size and strength) of the calf muscle
• A feeling of coldness in the legs or feet
• Changes in color of the feet; feet turn pale when they are elevated, and turn dusky red in dependent position
• Hair loss over the top of the feet and thickening of the toenails
• Poor wound healing in the legs or feet
• Painful ulcers and/or gangrene in areas of the feet where blood supply is lost; typically in the toes

Peripheral vascular disease (PVD) refers to diseases of the blood vessels (arteries and veins) located outside the heart and brain. While there are many causes of peripheral vascular disease, doctors commonly use the term peripheral vascular disease to refer to peripheral artery disease (peripheral arterial disease, PAD), a condition that develops when the arteries that supply blood to the internal organs, arms, and legs become completely or partially blocked as a result of atherosclerosis.

A number of different specialists may treat individuals with peripheral artery disease, for example, internists, family practitioners, or cardiologists may mange medication treatment. Interventional cardiologists or radiologists may perform angioplasty. Vascular surgeons may perform some surgical procedures to treat peripheral artery disease.

Peripheral artery disease (or peripheral arterial disease) that affects approximately 10 million adults in the U.S. About 5% of people over the age of 50 are believed to suffer from peripheral artery disease. Peripheral artery disease is slightly more common in men than in women and most often occurs in older persons (over the age of 50). The known risk factors for peripheral artery disease are those that predispose to the development of atherosclerosis. Risk factors for peripheral artery disease include:

• High blood levels of the "bad" LDL cholesterol and triglycerides
• Low blood levels of the "good" HDL cholesterol
• Cigarette smoking
• Diabetes mellitus (both type 1 and type 2 diabetes)
• High blood pressure (hypertension) or a family history of hypertension
• A family history of atherosclerotic disease
• Chronic renal failure
• Overweight or obesity
• Physical inactivity

In peripheral artery disease, the risk factors are additive, so that a person with a combination of two risk factors -- diabetes and smoking, for example -- has an increased likelihood of developing more severe peripheral artery disease than a person with only one risk factor.