Stay in circulation: Learn about PAD

Do your legs feel tired and achy?
Have you noticed any pain or cramping when you walk or climb stairs? If so, you may be among the thousands of Filipinos who have peripheral arterial disease (PAD): blockages of the arteries that supply the legs due to a buildup of fatty deposits or atherosclerosis (see illustration). This condition can also affect the blood conduits to the arms, stomach, and kidneys — vessels peripheral to those supplying the heart and brain. It becomes increasingly common as people age and experts estimate that more than 20 percent of people over age 70 have the disease.

Having PAD puts you at two to six times greater risk of dying of a heart attack or stroke. It is also one of the leading causes of lower-limb amputations. That’s because having PAD is really a red flag that you also have atherosclerosis in other blood vessels, putting your heart and brain at risk. “PAD is heart disease that hits below the belt,” remarks Allan T. Hirsch, MD, professor of epidemiology and community health at the University of Minnesota School of Public Health. “This is not a small event that will go away with time,” warns Dr. Hirsch.

The most common symptom is intermittent claudication — the leg cramping that occurs during walking or exercise and disappears with rest. It results from inadequate blood flow to the legs. Still, as many as 75 percent of people with PAD may not experience the classic leg symptoms, or some may just simply ignore the recurrent cramping pain in the leg muscles, ascribing it to old age. It would be a mistake to do so since the symptoms may also indicate the presence of inadequate circulation to the heart and brain.

“Both asymptomatic and symptomatic PAD are consistent and powerful independent predictors of coronary artery disease and cerebrovascular disease, and even death,” according to Beatrice A. Golomb, MD, associate professor of medicine at the University of California in San Diego, as reported in the August 15, 2006 issue of the medical journal Circulation. That’s not surprising as the risk factors for PAD are also the same as those for heart disease and stroke, namely cigarette smoking, diabetes, hypertension, and high cholesterol levels.

Diagnosing Pad

Early diagnostic testing for PAD can make a vital difference in preventing clogged arteries and reduced blood flow to your legs. You can avoid trouble by taking the right steps early. Besides giving you a physical exam, the doctor will also check for weak leg pulses, using the ankle-brachial index (ADI) test, which compares blood pressures in the legs and arms to determine how well blood is flowing. An ABI score less than 0.9 indicates significant narrowing of the leg arteries.

For some individuals, symptoms may lead to use of more complicated testing, such as Doppler ultrasound imaging, computed tomographic angiography, magnetic resonance angiography, and angiography of the leg arteries.

Treating Pad

The first line of treatment for mild PAD is lifestyle changes and, if need be, medications, according to new guidelines jointly issued by the American College of Cardiology, American Heart Association, Society for Vascular Surgery, and other organizations.

Smoking is a major risk factor for PAD, so if you’re a smoker, get help in quitting. If you have hypertension, elevated cholesterol or blood glucose levels (a sign of prediabetes or type 2 diabetes), work with your doctor to lower those numbers, taking the proper medications if necessary. These include statin drugs to lower cholesterol, antihypertensive medications, and aspirin or other therapies to prevent blood clots that could lead to a heart attack or stroke.

The importance of treating these factors is demonstrated by a recent study that found that cholesterol-lowering statins reduced the risk of cardiovascular events by about 25 percent in people with PAD but without diagnosed heart disease. And one year of atorvastatin (Lipitor) therapy helped people with PAD walk longer without leg pain.

Exercise is a cornerstone of treatment for intermittent claudication: Several recent studies have shown that a medically-supervised exercise program, in which patients build endurance by walking on a treadmill three or more times a week for at least three months, can reduce leg pain and help people walk longer. Drugs such as cilostazol (Pletal) and pentoxifylline (Trental) can also relieve leg pain.

Opening Arteries

When symptoms continue despite medication and exercise, leg angioplasty or leg bypass surgery is an option. Angioplasty can open leg arteries in the same way it opens blocked coronary arteries. It is generally favored for small, localized obstructions. In this procedure, a thin flexible tube is guided to the site of the blockage and a balloon is inflated to help improve blood flow through the narrowed artery. Stents, small metal devices that act like scaffolds, are usually inserted during angioplasty to help prevent re-closure of the arteries. Unlike coronary stents, the stents used in leg arteries are much longer and extremely flexible so that they can bend and twist as the leg moves.

A new type of stent, the SMART stent system, was approved in late 2003 and is used to treat blockages in the iliac artery, which carries blood to the legs. Unlike stents that are expanded by inflating a balloon, the SMART stent is self-expandable, enlarging to a preset diameter after it is released into the blood vessel.

Scar tissue commonly forms around implanted stents and may re-clog blood vessels. Stents coated with a drug to prevent the artery from squeezing shut again — so-called drug-eluting stents — are commonly used in coronary artery angioplasties and are now being tested in patients with PAD. In a European trial comparing drug-eluting and uncoated stents in patients with PAD, the rate of vessel re-narrowing was significantly lower in patients treated with the drug-eluting stents.

Leg bypass surgery is usually preferred for treating more widespread disease in the leg arteries. In this procedure, a vein taken from another part of the leg or a vessel made from a synthetic material is attached above and below the obstruction to reroute blood flow. A 2004 study in the Journal of Vascular Surgery showed that treatment with statin drugs and angiotensin-converting enzyme (ACE) inhibitors prior to leg bypass surgery significantly increased the success of the operation.

Finally, a promising new technique called therapeutic angiogenesis seeks to restore blood supply to the legs by promoting the growth of new blood vessels. Angiogenesis may be accomplished by injecting a gene that controls production of a protein that enhances new blood vessel growth, by administering the protein itself, or by implanting bone marrow stem cells that can stimulate blood vessel formation. The US National Institutes of Health has just begun a clinical trial to evaluate the safety and efficacy of therapeutic angiogenesis using the gene therapy approach.

Meanwhile, if you have PAD, here’s what you can do now:

• Engage in a fitness program that includes walking and leg exercises.

• If you smoke, get help to stop immediately.

• Reduce your diabetes risk by eating fruits and vegetables regularly, and avoid prolonged fasting.

• Avoid foods high in simple carbohydrates and trans fats, such as french fries, doughnuts, and pie crusts. Adopt a diet low in saturated fat.

• Consume alcohol minimally or moderately and with meals.

And the most important thing to consider, stresses Director Elizabeth G. Nabel, MD of the US National Heart, Lung and Blood Institute (NHLBI), is to remember that “symptoms of PAD should not be mistaken for or easily dismissed as the usual inevitable consequences of the aging process.”

If you want to stay in circulation, you must be serious about PAD.