This increasingly common disorder often goes undetected in women until serious problems arise.
Older women are learning that cardiovascular disease isn't confined to the chest. Atherosclerosis, once known as "hardening of the arteries," is the disease process at the root of most cardiovascular problems. It affects not only the vessels that feed the heart but also those that serve the rest of the body. When atherosclerotic plaque and blood clots reduce blood flow to the legs or, less often, to the arms, the condition is called peripheral artery disease (PAD). PAD makes walking painful and slows injury healing. In the worst cases, it can result in the loss of a toe, foot, or leg — or even death.
Like coronary artery disease (CAD), PAD was once thought to be a problem mainly for middle-aged men. One reason is that men that age are more likely than women to complain to their doctors about leg pain. Another reason is that men with PAD are more likely than women to have CAD as well, so they come to the attention of clinicians sooner. Women with PAD tend to develop their first symptoms in their 60s and 70s — a decade later than men. By then, they may have other conditions like arthritis or peripheral neuropathy (nerve damage) that mask PAD symptoms and delay diagnosis. By the time a woman is finally diagnosed, she's likely to have more severe disease.
Who gets PAD?
The risk factors for PAD and CAD are virtually identical, and include the following:
Age. About 3% of people under age 60 have PAD, and so do as many as 20% of those over age 70. Late in life, a higher proportion of people with PAD are women. One study with nearly 7,000 participants found that at ages 85 and over, almost 40% of the women had PAD, while less than a third of the men had the condition.
Cigarette smoking. Exposure to tobacco raises the risk of atherosclerosis by constricting arteries and promoting inflammation. A 2011 report from the Women's Health Study found that compared with nonsmokers, smokers whose lifetime exposure to cigarettes was 10 to 29 pack-years were six times more likely to develop PAD; those with a lifetime exposure of 30 or more pack-years had 11 times the risk. (A pack-year is a measure of tobacco exposure: one pack of cigarettes a day for 10 years, two packs a day for five years, and half a pack a day for 20 years each adds up to 10 pack-years.)
Diabetes. One in three people who are over age 50 and have diabetes will develop PAD.
High blood pressure. The risk of PAD is higher for people with readings of 130/80 and above.
Unfavorable lipid profile. Too much "bad" LDL cholesterol and too little "good" HDL cholesterol are linked to PAD. Risk increases 5% to 10% for every 10-point rise in LDL levels.
Ethnicity. African American women are twice as likely as Caucasian women to develop PAD.
Heredity. Family history accounts for about 20% of a person's overall risk.
The symptoms of PAD range from mild to debilitating and often progress in the following way:
Intermittent claudication. The term claudication comes from the Latin verb claudicare, "to limp," which pretty much tells the story. When leg arteries are narrowed, they can't expand enough to provide muscles with the extra blood they need during exercise. The oxygen-starved muscles below the obstruction — usually in the calf — may cramp, become painful, or feel heavy and tired, forcing the walker to halt or limp. The pain subsides with rest. If the blockage is higher up, the pain may be felt in the thigh or buttocks.
Pain or numbness at rest. As the artery becomes narrower, the leg gets insufficient blood even when it's at rest. At this stage, the leg and foot may be cool, pale, and even numb. Foot and toe pain and tingling may disturb sleep. Unlike the pain from a blood clot, PAD pain can be relieved by standing or dangling the leg over the edge of the bed, to force blood down through the arteries.
Tissue damage. The most severe stage of PAD is critical limb ischemia (CLI), in which blood flow is so reduced that sores don't heal and gangrene can develop. Only 1% to 2% of patients with PAD develop CLI, but all of them will need surgery to restore blood flow, and for almost 30%, amputation will ultimately be required.
PAD is diagnosed with a test called the ankle-brachial index, or ABI, which compares systolic blood pressure in the ankle and the arm. In most healthy adults, the ratio of ankle to arm pressure is between 1.0 and 1.4. If PAD is present, it's less than 0.9, and the disease is considered severe if it's 0.5 or lower. When an ABI test indicates PAD, one or more of the following imaging studies may be ordered:
Doppler ultrasound. A wandlike transducer is pressed against the legs, emitting sound waves that are reflected by the arteries to create an image of the vessels. Doppler also provides information on blood-flow velocity and turbulence.
Magnetic resonance angiography. An MRI scan is taken after a contrast agent called gadolinium is administered intravenously, providing a detailed image of the arteries.
Computed tomography angiography. A CT scan is taken after an intravenous infusion of an iodine-containing contrast solution. Like magnetic resonance angiography, this provides a detailed picture of the arteries.
PAD in the arms
Although PAD is more common in the legs, the arms aren't immune. Even more than PAD in the legs, PAD in the arms is easily confused with arthritis or a heart attack. Symptoms include
If you have any of the above symptoms, test your blood pressure, either with a home monitor or at a pharmacy, or have your clinician check it. A difference in systolic blood pressure of 10 to 15 points or more between the two arms is a fairly reliable indicator of PAD in one arm.
Lifestyle and medical treatment for PAD
A diagnosis of PAD indicates that you're at risk not only for mobility problems but also for heart attack and stroke. Here's how you can reduce your risk:
Get exercise. If intermittent claudication makes it hard to walk or bike, you can increase your leg strength and walking speed with a targeted exercise program. You may be able to exercise harder and longer if you take a medication that increases blood supply to the legs. Two such medications have been approved for PAD: cilostazol (Pletal), which dilates blood vessels; and pentoxifylline (Trental, Pentoxil, Pentopak), which improves blood flow.
Don't smoke. In the Women's Health Study mentioned earlier, quitters reduced their risk for PAD by 60% within 10 years.
Manage chronic conditions. Managing conditions that contribute to PAD can help reduce symptoms and reduce your chances of a heart attack or stroke. Lose weight if necessary, and make sure blood sugar is under control if you have diabetes. Cholesterol-lowering statin drugs and blood pressure–lowering medications are effective in treating PAD as well as CAD.
Take medications to prevent blood clots. Low-dose aspirin or clopidogrel (Plavix) is strongly recommended. These drugs will not alleviate symptoms of PAD or arrest its progression, but they can reduce the risk of heart attacks and other cardiovascular events by preventing the formation of blood clots in narrowed arteries.
Don't wear compression stockings. Compression stockings further impede blood flow in people with PAD. Talk to your clinician if you've been wearing them to prevent blood clots or leg swelling.
Treating peripheral artery disease
Blood flows freely through a normal artery (A). In peripheral artery disease, atherosclerotic plaque narrows the artery and impedes blood flow (). During angioplasty to restore blood flow, a stent may be inserted to keep the artery open (C).
Revascularization — restoring blood flow
The two main approaches to revascularization in the legs are the same ones used to restore blood flow to the heart — balloon angioplasty and bypass surgery. As with heart disease, women with PAD have traditionally been less likely than men to be offered these procedures. Women tend to be older and sicker when they develop CLI, so they've had a higher risk of complications. Also, bypass has been less successful in women's arteries, which are smaller than men's. But a 2011 study found that women who underwent revascularization immediately after developing CLI lived longer and were less likely to require amputation than those treated solely with medication and physical therapy.
Bypass surgery is performed under general anesthesia and requires an overnight stay in the hospital. Surgeons usually remove a vein from the patient's leg and graft parts of it into the affected artery to skirt the obstruction. Synthetic grafts have given poor results, so angioplasty is advised when no vein is available. Angioplasty is usually performed on an outpatient basis under local anesthesia and sedation. First, a small incision is made near the groin and a contrast solution is infused to outline the arteries. Guided by an image on a monitor, the surgeon inserts a balloon-carryingcatheter through the incision into the leg artery and snakesit down to the obstruction. The balloon is inflated to openthe artery. A mesh stent (sometimes coated with a clot-preventing drug) may be inserted to keep the artery open.
Other approaches include freezing, shaving, or vaporizing the obstruction with instruments inserted through the catheter. To reduce the risk of clotting, women are advised to discontinue hormone therapy for a few weeks before and after angioplasty.
Bypass was once the preferred approach for legs affected by CLI, but since the early 2000s, clinical trials have found that angioplasty is just as effective, with fewer complications. Now more surgeons are advising women to consider angioplasty as soon as an obstruction is identified and before the disease progresses to CLI.
If you're at risk for PAD
If you have several risk factors for PAD — even if you don't have symptoms — you should talk to your clinician about an ABI test during your next physical. A diagnosis of PAD is no longer a grim prediction of the loss of life or limb. But it means you must do everything you can to lower your chances of becoming disabled or having a heart attack or stroke. For a list of resources on peripheral artery disease, go to www.health.harvard.edu/womenextra.