What is Peripheral Arterial Disease?

Atherosclerosis (literally, “hard arteries”) is perhaps the most prevalent disease process in Americans over the age of 50. In this condition plaques, which are generally composed on a mixture of cholesterol and blood cells, build up along the walls of arteries and may eventually reduce the diameter of an artery to the point of restricting blood flow (a narrowing of an artery is called a stenosis). When atherosclerosis limits the flow of blood into the lower extremities a condition called peripheral arterial disease (PAD) is said to be present.

What are the Symptoms of PAD?

The “classical” or “textbook” symptom of PAD is pain in the lower extremities and/or buttocks that occurs while walking that is then relieved by resting. This particular type of pain is known as intermittent claudication. It is well-known that the time required for intermittent claudication to occur is an indication of the severity of PAD. For example, if pain occurs after walking a short distance (less than 2 city blocks) the extent of the patient’s PAD is assumed to be more severe than if similar pain occurred only after walking for 6 blocks.

Other signs of PAD that a health care provider might find in PAD include decreased to absent pulses in the groin or legs, a poorly-healing sore or injury (particularly on the feet), toenails that are thickened and discolored, and an absence of hair on the calves or feet.

Some medical conditions (and risk factors) are associated with PAD. These conditions include:

� Smoking (perhaps the most significant risk factor)
� Male sex (much higher incidence of PAD in men)
� A family history of circulatory conditions
� Diabetes (Insulin-dependent diabetics will often have circulation problems)
� Hypertension
âÂ?¢ Elevated lipoprotein (cholesterol) levels in the blood (hyperlipidemia), particularly if there are elevated levels of low-density lipoproteins (the so-called “bad cholesterol”)

How is PAD Diagnosed?

The diagnosis of PAD can usually be established based on the nature of the pain that occurs with exercise and the physical signs mentioned above. There are, however, several non-invasive (not requiring an incision or needle puncture) tests that many health care providers will order that will both confirm the diagnosis of PAD and serve as a baseline with which to monitor the progression or improvement of PAD.

The simplest of these can usually be done in the health care provider’s office and is called an Ankle – Brachial Index (ABI). This involves using an ordinary blood pressure cuff and a special type of stethoscope called a Doppler Probe to measure the blood pressure at the ankles and in the arms. The ankle blood pressures are then divided by the higher of the arm blood pressures to determine the ratio (the ABI) of the ankle pressure to that in the arm. Generally speaking, an ABI âÂ?Â¥ 0.95 is considered normal by the vast majority of health care practitioners while an ABI âÂ?¤ 0.50 indicates that there is probably a significant obstruction in one of the major leg arteries.

In many cases the health care provider may want to get a general idea of the approximate level at which an obstruction may be present. In this case he or she may order Segmental Pressures exam. This involves measuring the blood pressure at the ankle by using special blood pressure cuffs that will usually be placed on the upper thigh, just above and below the knee, and at the ankle. Ratios � 1.3 at the upper thigh are considered as normal as is a change of � 0.1 between any two successively lower levels.

Since the pain associated with PAD is brought on by exercise many testing centers will take the above-mentioned measurements while the patient is resting and then again immediately following exercise. If the ABI falls following exercise, the test is considered to have confirmed the presence of PAD.

Sometimes, particularly if surgical correction of the arterial obstructions is being considered, the patient will be referred for angiography. Traditionally, this involved injecting a special type of x-ray dye and then taking a rapid series if x-rays that would be used to determine the level and extent of the arterial obstruction(s). Today there are more options available including CT (Computed Tomography, “CAT Scan”) angiography as well as a relatively new application of Magnetic Resonance Imaging (MRI) called Magnetic Resonance Angiography (MRA). The choice of which procedure to use is generally based on the preferences of the health care provider.

What is the Treatment for PAD?

No matter what form of treatment a health care provider may ultimately recommend, he or she will order a set of laboratory tests that will give an overall picture of the patient’s health in general and both the amount and type of lipids (fatty chemical compounds) present in the patient’s circulation. If these levels are considered to be too high, the health care provider will recommend dietary changes and start the patient on one of the lipid-lowering drugs. The provider will also order the patient to stop all forms of tobacco use.

There are two forms of treatment for PAD: medical and surgical.

Medical treatment of PAD generally consists of a “two-tiered” approach. The first tier is encouraging the patient to walk until forced to stop by leg discomfort, waiting until the discomfort passes, and then walking again until being forced to stop. This is called “walking through the pain” with the rationale of this therapy being that exercise will either halt the progression of PAD or improve the patient’s exercise tolerance.

The second tier is a trial of a drug called pentoxifylline (TrentalÃ?®). TrentalÃ?® causes a decrease in the viscosity (“thickness”) of the blood itself. This decrease in viscosity means that blood can flow more easily across a partially-blocked section of an artery, particularly during exercise. The only drawback to TrentalÃ?® therapy is that this drug can cause very unpleasant gastro-intestinal problems, with nausea being the most commonly reported side effect.

The surgical treatment of PAD is usually considered after medical therapy has been tried and failed to produce an improvement in the patient’s symptoms. When discussing surgical treatment options, the health care provider will explain the risks and potential benefits of the proposed surgical procedure with patient. As with medical treatment, surgical procedures fall into two broad categories.

The first of these is balloon angioplasty, which involves inserting a long, thin plastic tube (catheter) into an artery and then advancing it until it encounters the area of the plaque that is responsible for the reduction in blood flow. Once the catheter is in place a balloon at the end of the catheter is inflated, the obstructing plaque is “fractured,” and the obstruction is at least made less severe if not corrected.

The second type of surgical treatment of PAD is called arterial bypass grafting. This involves placing a synthetic (man-made) graft from a disease-free area above the level of obstruction to an area below the obstruction (bypassing the obstruction). As there are many potential variations of this procedure, the surgeon that will actually perform the operation will always discuss the specific details of the planned procedure with the patient.

Of the two surgical options angioplasty is by far the less risky since it avoids the risks associated with anesthesia and several potential post-operative complications. Unfortunately, angioplasty is most effective when used to treat a discrete stenosis in an otherwise “normal” artery. Since atherosclerosis is a systemic (occurring throughout the body) condition angioplasty is not an option in many patients with PAD.

Bypass grafting, although better suited for those patients with multiple areas of plaque, is riskier than angioplasty because it includes the risks associated with general anesthesia and post-operative complications such as infection or respiratory complications. These potential complications are always anticipated and aggressive post-operative care has minimized, but not eliminated these complications.

Regardless of which surgical therapy is selected, the long-term success of either rests on following two very simple instructions: 1) No Smoking and 2) following you health care provider’s instructions regarding medication and/or diet.

Disclaimer

The information presented in this article and its included links is of an informational nature only and is not intended as a recommendation of any changes in the reader’s health care program. Before making any changes in diet, medications, or other treatments the reader is strongly advised to consult with their health care provider.

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