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Facts about Intermittent Claudication ("poor circulation")
by NSCG, Ltd.

Intermittent Claudication affects millions of Americans every year and is often the first symptom of peripheral vascular disease. It is an important disease to recognize because of its prevalence and the availability of many new nonsurgical treatment options. Although common, patients do not always report their symptoms, leaving the problem untreated. Furthermore, the presence of peripheral vascular disease in the legs may be a marker of similar disease in other organs, such as the heart and brain.

What is Intermittent Claudication?

Intermittent claudication is the primary symptom caused by underlying peripheral vascular disease ("hardening of the arteries" or atherosclerosis of the legs). It is usually described as a cramping, tightness or fatigue in the calves, thighs or buttocks, occurring primarily with walking, and relieved upon resting. Its onset is fairly predictable as it develops at the same distance traveled. With progression of the underlying disease, symptoms begin at shorter and shorter distances walked and ultimately, will even occur at rest.

Atherosclerosis has its onset very early in life with fat (especially cholesterol) being deposited beneath the inner lining (endothelium) of arteries. Over years to decades, as more fat is deposited, cracks form within and on the surface of these early plaques. Layers of blood clot then form over the injured (cracked) surface. Eventually, this layered plaque significantly reduces an artery’s central lumen (open area) and blood flow through the artery is reduced.

Not all leg cramping, tightening or fatigue is claudication. Severe impairment of the nerves exiting the lower spine and going to the legs can cause similar ("pseudoclaudication") symptoms.

What is the Natural History of Intermittent Claudication?

All tissues of the body require oxygen and nutrients to live and function normally; the legs are no exception. At rest, the tissues (muscle, skin, nerves, etc.) of the legs require only a modest amount of blood flow to provide for their metabolic needs. With walking, the metabolic needs of the legs increase, and blood flow must similarly increase to meet these increased demands. As plaque builds up in the leg arteries, blood flow (and its resultant oxygen and nutrient supply) decreases causing an altered metabolism in these inadequately supplied tissues (lactic acidosis) and pain.

Once blood flow is reduced to the point that even resting metabolic needs are not met, the leg tissues begin to break down and non-healing, open sores (ulcers) appear. Bacteria infest these sores and the resulting infection can spread into the blood stream (a life-threatening condition known as sepsis) or deep into the bone and muscle causing gangrene. These last conditions may require limb amputation as a life saving, albeit drastic, treatment.

As atherosclerosis is an inevitably progressive disorder, claudication will inevitably worsen.

Do any Risk Factors influence the development of Intermittent Claudication?

Risk factors for the development of peripheral vascular disease (PVD) and intermittent claudication (IC) are similar to those for coronary heart disease. Smoking, however, probably plays a larger role in PVD than does cholesterol, although both are important risk factors. Smokers have at least a four times greater risk of developing PVD than nonsmokers, and smoking cessation strongly reduces the progression of disease. Smoking causes direct damage to the endothelium of blood vessels by generation of carbon monoxide and increases the likelihood of clot formation. Hypertension increases the risk three times compared to non-hypertensives probably by gradually damaging the endothelium. Diabetes increases the risk by three times over the normal population by causing disease of the smaller arteries of the legs. Unfortunately, because of the decreased pain sensation found in many diabetics, the disease may not be recognized until ulceration appears. Finally, cholesterol plays a significant role in the early development and progression of the atherosclerotic plaque.

How is Intermittent Claudication diagnosed?

Once intermittent claudication is suspected, a physician will usually confirm the diagnosis by ordering relatively simple, non-invasive tests to estimate the blood flow to the legs. The simplest of these tests is the Ankle – Brachial Index (ABI) which is just a ratio of the systolic blood pressure measured simultaneously in the leg and arm. An ABI ratio less than 0.8 implies significant arterial obstruction while a ratio of 0.5 or less implies critical obstruction. Occasionally, the ABI ratio can be normal even with significantly obstructed arteries. If the ratio is remeasured after a casual walk, however, an abnormal reading will usually be found.

Duplex doppler studies can provide an accurate non-invasive ultrasound picture of the leg arteries along with a relative estimate of the severity of any arterial narrowings. As the arteries to either leg can be 2.5 to 4 feet in total length, and as a patient with intermittent claudication can have a narrowing at only one level or at multiple sites, duplex doppler scanning provides an excellent non-invasive arterial road map.

Once the diagnosis is confirmed, and if some form of revascularization therapy (bringing new blood supply) is being considered, angiography is then performed. An invasive but non-surgical test, angiography involves inserting a small, hollow, flexible, plastic tube (catheter) via a needle puncture into the artery and then injecting a contrast media (dye) into the artery while simultaneously taking x-ray movies. This test provides the most accurate assessment of the extent of arterial narrowing so that a treatment plan can be devised.

What Treatments are available for Intermittent Claudication?

Risk Factor modification

The frontline treatment for atherosclerosis anywhere in the body involves risk factor modification.
Smoking cessation is critical to limiting the progression of disease and limiting its symptoms.
Aggressive cholesterol lowering (see Facts about Cholesterol and Lipid Disorders) is necessary to help slow its inexorable progression.
Meticulous diabetic management, bringing fasting sugar levels and glycohemoglobin levels to the normal range is also most helpful.
Exercise helps maintain muscular fitness and may stimulate collateral blood vessel growth.

Medical Therapy

The most commonly used medications for the treatment of intermittent claudication fall into three general categories.

1) Drugs that reduce the ability of the blood to clot by inhibiting platelet (microscopic circulating particles that, when stimulated, adhere to one another and to plaque to initiate the formation of a clot) function, play an integral role in the treatment of all forms of atherosclerosis. Aspirin should be used in all such patients. More recently, even more potent platelet aggregation inhibitors have been introduced, including ticlopidine and clopidagrel. These types of drugs may effect disease progression but do not alter claudication symptoms.

2) Patients with severe and diffuse obstruction of the smallest arteries in the legs may benefit from the use of rheologic agents. This class of drugs alters the chemistry of the surface of red blood cells rendering them more slippery and thus easier to slip through the tightest of narrowings. The only rheologic agent presently approved for use is pentoxyphylline.

3) One of the most exciting advances in the medical treatment of intermittent claudication has been the introduction of the drug cilostazol (PLETAL®). While many of the biochemical effects of cilostazol are known (clot inhibition, blood vessel dilatation, triglyceride lowering, reducing cellular energy production), the exact mechanism for reducing claudication is not clear. In any event, studies have shown that 12 weeks of cilostazol use reduces claudication severity and increases walking distance by as much as 40% when compared to a placebo (sugar pill).

Revascularization

While many patients with intermittent claudication receive enough symptomatic benefit from risk factor reduction and a combination of medicines, a significant percentage of patients will remain functionally limited. Patients with claudication at rest and especially patients with non-healing ulcers, will, in all probability, not improve unless a new and dependable source of blood can be provided to the affected limb.

1) Surgery

For years, the only form of revascularization available was surgical. This technique, similar to coronary bypass, involves the surgical imposition of a new conduit attached above and below the artery’s narrowed segment(s). The conduit used is either a synthetic material or a piece of surgically excised vein. While generally highly successful, this is a major operation that almost invariably requires general anesthesia and is associated with a considerable recovery period. This surgery may be contraindicated in patients suffering from concomitant severe heart or lung disease.

2) Angioplasty

As balloon angioplasty and stent use became finely honed and successful tools in the treatment of coronary atherosclerosis, these same tools and skills have been developed for use in the arteries of the legs. (see Facts about Coronary Angioplasty) The techniques, skills and equipment used in each of these conditions are quite similar.

Balloon angioplasty (with or without stent implantation) does not require general anesthesia but is performed using mild sedation and a local anesthetic. As with an angiogram, a catheter is inserted into the affected artery via a needle puncture, an even smaller catheter is then threaded down the artery and across the narrowed segment, and the balloon at the catheter’s tip is inflated. The narrowed segment is thus expanded and the plaque compressed against the arterial inner wall. Depending on the narrowings location and other technical factors; a stent may be used (a metallic coiled or woven tube). A one-night hospital stay may be required but there is no appreciable recovery period and patients may return to their usual normal activities immediately. In general, the higher up in the leg the narrowing, the more likely a stent will be used, and the more likely a long-term success will be achieved. Stenting of iliac arteries (the arterial segment between the waist and groin) carries a 90% five-year patency rate. Balloon dilatation of the smaller arteries below the knee carries a lower, but still excellent, long-term patency rate.

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