If you’ve never heard of Peripheral arterial disease, you’re certainly not alone
By Wendy Haaf
In the summer of 2013, Pat Garry of London, ON, was visiting a friend in Toronto’s hilly Beaches neighbourhood when he noticed a pain in the lower part of his left calf. “I found I really struggled when walking,” he recalls. Having quit smoking three years earlier, Garry considered himself in good shape. Less than a year before, during a period between jobs, he’d routinely walked with his dog for three or four kilometres at a stretch without a second thought. “I thought, Great—my doctor wants me to do cardio, but I can’t, not because I’m short of breath, but because I have a sore foot.”
Thinking the culprit must be an inflamed tendon or sore muscle, Garry went to see his family physician, who gave him some exercises to try. “Nothing worked. I wasn’t getting any better,” he says. “Walking two flights of stairs, I’d have to stop and rest.”
Ultimately, Garry’s doctor sent him to a specialized clinic to have the blood flow in his legs checked. There, he was given the news that he, like an estimated 800,000 to one million Canadians, has peripheral arterial disease (PAD), a vascular condition linked with a greatly increased risk for several serious health problems. In fact, Garry was lucky: because his discomfort had driven him to seek medical attention and, ultimately, a diagnosis, he could then take steps to cut those risks down to size. Even when PAD causes symptoms, which it does in only about 50 per cent of cases, people often chalk them up to the effects of arthritis or aging, with just one in three broaching the subject with a health-care provider.
What is PAD, and why is it a cause for concern? Just as the arteries near the heart and those supplying the brain can become narrowed and blocked by deposits of fat, calcium, and fibrous tissue called atherosclerotic plaque, so, too, can those carrying blood to the legs. (PAD can also occur in the arms, though much less commonly, says Dr. Thomas Forbes, a professor and chair of vascular surgery at the University of Toronto and a vascular surgeon at Toronto General Hospital’s Peter Munk Cardiac Centre.) These bottlenecks in the blood supply to the legs can make themselves apparent when walking or climbing stairs. As the muscles in the calf, thigh, and buttock begin working harder, they need more oxygen, so if the normal supply of oxygen-rich blood is slowed to a trickle due to a narrowed artery, the result can be anginalike cramping pain (or, less typically, heaviness, fatigue, and/or numbness).
Referred to as intermittent claudication (the Latin word for “limping”), this pain often follows a predictable, reproducible pattern.
“The classic pattern would be: You walk a certain distance and you get a kind of cramp or pain in the back of your calf or your thigh; you stop and it goes away,” explains Dr. Kathryn Myers, chair and chief of general internal medicine at London Health Sciences Centre and professor of medicine at Western University in London, ON. “You start again, and after about the same distance, the pain comes back.”
Blockages so severe that they pose an imminent threat to the foot or leg—called critical limb ischemia—cause a different symptom pattern. (This subgroup comprises only about 10 per cent of PAD patients.) “Not only does the person get pain with walking, but he or she has pain in the foot all the time,” says Forbes, who is also president of the Canadian Society of Vascular Surgery. This type of pain tends to worsen when you lie down and get a little better if you dangle the affected leg over the side of the bed. Most people with PAD this severe usually don’t put off seeking medical attention, which is a good thing, since prompt intervention is required to restore blood flow and thereby reduce the associated risks for sores, ulcers, and gangrene.
Health Implications of PAD
As you might imagine, pain that comes on with walking can limit normal activity and interfere with getting enough exercise to protect your health.
“Peripheral arterial disease causes significant morbidity and quality of life issues such as difficulty walking,” Myers says. But that’s only part of the story.
“PAD is a harbinger of atherosclerosis in general,” says Dr. Guy DeRose, a vascular surgeon at London Health Sciences Centre, “so these patients are at a higher risk for coronary artery disease and cerebral vascular disease—so heart attack and stroke.”
Just how much higher? People with PAD are about eight times more likely than those without the condition to have a heart attack or stroke: in fact, PAD is an even more powerful predictor of these problems than other potent risk factors. For instance, in one study that followed patients with confirmed narrowings in arteries to the heart, brain, or legs, the latter group had the highest rate of serious artery-blocking events such as heart attack, stroke, and cardiovascular death: 21.1 per cent over the course of a year versus roughly 15 per cent for each of the other groups.
But the heart and brain are not the only organs at risk in PAD, notes Marg Lovell, a clinical trials nurse at London Health Sciences Centre and founder of the London, ON, chapter of the Canadian Society of Vascular Nursing. “PAD is a serious marker for blocked arteries in other organs, such as the stomach and kidneys,” she explains. Furthermore, PAD is linked with higher-than-average rates of depression and a hastening of functional decline, even in the absence of symptoms. Finally, poor blood supply to the legs can contribute to impaired wound healing.
And yet, Myers says, “peripheral arterial disease is both underdiagnosed and undertreated, because it’s not recognized in the same way as stroke and heart attack.” Indeed, in a study called PARTNERS, of 7,000 subjects considered at high risk of developing PAD, 44 per cent proved already to have the condition.
Who is most likely to develop PAD? Not surprisingly, many of the traits linked with an increased risk for heart attack and stroke overlap with the risk factors for PAD, beginning with age. “PAD is more common in people over age 60,” Lovell says.
(In the PARTNERS study, between 15 and 29 per cent of those over age 70 with no other risk factors had PAD.)
According to Forbes, the condition is also more common among people who have a family history of PAD, heart attack, or stroke. The same goes for those with a personal history of the latter two conditions: if you’ve been diagnosed with vascular disease or have had a previous heart attack or stroke, your odds of getting PAD are about one in three. Ethnicity also factors into the equation: having Aboriginal, Latino, or African ancestry is linked with an increased risk.
When it comes to risk factors you can control, “smoking is number one,” Forbes says. In addition, risk increases in step with the amount smoked, from double in former smokers to eight times in heavy smokers (more than 25 cigarettes a day), all versus risk for those who’ve never smoked.
The second leading controllable risk factor is diabetes, which is linked with a two-to-fourfold increase in the likelihood of developing PAD; if you’re over 50 and have diabetes, you have a one-in-three chance of ending up with a constriction in the blood vessels to your legs. PAD also tends to strike people with diabetes at a much younger age than those without the disease.
“In our study, the average age was around 60, when typically, in a population of people without diabetes, it would be 75 or 80,” says Pamela Houghton, a physical therapist and chair of the Masters of Clinical Science in Wound Healing in the School of Physical Therapy at Western University in London, ON. High cholesterol and high blood pressure round out the list of risk factors.
Because PAD often doesn’t overtly announce its presence and because we have strategies for mitigating the cardiovascular risk it confers, some medical experts recommend routinely screening certain groups for the condition.
For example, the Canadian Cardiovascular Society consensus guidelines advocate screening men over 40 and women who are over 50 or menopausal who also: are smokers; have diabetes; have a family history of PAD, coronary artery disease, or stroke; have a blood fat abnormality (including high levels of LDL cholesterol or triglycerides); or have high blood pressure.
“Peripheral arterial disease is quite prevalent in patients with diabetes, and I think that might get underrecognized,” Myers says, “because when people with diabetes get foot problems, the problems are assumed to be due to diabetic nerve damage. But often they go together, so while they do have diabetic neuropathy, they also have PAD.
“It’s really important in patients with diabetes to think about doing an ankle brachial index.”
An ankle brachial index is the tool most commonly used to confirm a diagnosis of PAD. Using a handheld ultrasound device, “blood pressures are checked in the arm and leg,” Lovell explains, “and a ratio comparing the ankle pressure to that of the arm is calculated.” PAD is present if the ankle brachial index is 0.9 or lower, with 0.4 or below deemed severe.
An important part of screening is a careful physical exam, which includes checking the strength of the pulses in the legs and feet and looking for clues such as differences in skin temperature or colour, poor nail and hair growth, and the presence of any sores or wounds. Getting a medical history by asking specific questions about any leg discomfort is another key strategy clinicians will likely use. In people with symptoms, these two steps often sort out whether the source of the pain is an interruption in blood flow or something else, such as a nerve problem.
“In the majority of patients, well over 90 per cent, we have a very good indication of the cause of pain just from a good history and physical,” says London Health Sciences Centre’s Dr. DeRose. “Unless someone presents with limb-threatening ischemia [a deficient blood supply], we don’t do any type of invasive imaging,” such as angiography (a type of X-ray that involves injecting a special dye).
If you’re diagnosed with PAD, the first order of business is to take control of any relevant risk factors—for instance, by quitting smoking, adopting a Mediterranean diet (including limiting salt), trying to lose excess weight, and using medications to bring blood pressure, blood cholesterol, and blood sugar levels down to recommended targets.
“If you have symptomatic peripheral arterial disease, you should be on an antiplatelet drug, usually Aspirin,” Myers says. These medications prevent the formation of potentially artery-clogging clots, thereby reducing heart attack and stroke risk. Similarly, a cholesterol-lowering statin medication is recommended for all patients with symptomatic PAD, regardless of their cholesterol levels. This is because statins appear to reduce the risk for a heart attack in patients at high risk—including those with PAD.
Making these kinds of changes “can reduce the complications of atherosclerosis that may cause patients not only to lose their limbs but also to have an earlier death,” DeRose says.
The other key component of managing PAD is a regular walking program. “In general, we advise a minimum 30-minute walk daily at a normal pace,” DeRose says. “Gradually walk until you have pain that you can’t tolerate any longer, have a little rest, let the pain subside, and then keep going.”
“People often have the misperception that, because they get pain when they walk, walking is bad for them,” Myers says, “but it’s actually a good thing to walk to the level of the pain and even through it.”
Why? For starters, there’s good evidence that many people who do this develop what are called collateral vessels around the blockage, she says. In addition, a review of 21 published studies found that at least six months in a regular walking program such as the one described by DeRose can reduce average pain-free walk time for people with PAD by 179 per cent, and maximum walk time by 122 per cent.
“We say that if you’re able to control your risk factors and not smoke, then the worst you’re going to be is probably how you are right now,” says Toronto General Hospital’s Dr. Forbes. “With exercise and some time, this can get better; we just don’t know how much better it will get. So we tell patients, ‘Let’s see you in another three to six months, do another ultrasound, and see how you’re doing.’”
Pat Garry, who has Type 2 diabetes and was 56 when he first developed symptoms of PAD, took his doctors’ advice and got his risk factors under control. “From November 2014 to March or April of this year, I lost 25 pounds. I was on the treadmill every night, I was reading food labels—I was doing everything I could,” the London, ON, native says. While he could walk at a leisurely pace for long periods with no problem, Garry remained unable to do the more taxing cardiovascular exercises his family doctor had prescribed to help control his diabetes and reduce his risk for heart attack. “I would go 15 minutes flat out and then I’d have to wait five minutes before I could even go up the stairs,” he says. “I wasn’t getting any better.”
“Usually, patients are the best judges of whether they’re doing well enough or not,” Forbes says. “If they’re not, at some point they’ll say, ‘Look, I’m just not happy with what I’m able to do.’ And we’ll say, ‘Okay, let’s look at what the possibilities are,’ and we’ll put them through a fancier X-ray or a CT scan.” These imaging tests help reveal the location and extent of any blockages—two factors that help determine which type of blood-flow-restoring intervention is most appropriate or feasible.
“There are numerous procedures that can be carried out,” DeRose says. In angioplasty, a catheter is threaded through an artery in the groin to the site of the narrowing and a balloon mounted on the tip of the catheter is inflated. Open bypass surgery involves using either vessels harvested from the patient’s own body or synthetic grafts made of Dacron or Teflon to reroute blood flow to the affected area. “If we do a bypass below the knee,” DeRose explains, “we do everything we can to use the patient’s own veins, because the vessels are so small that the synthetic grafts don’t stay open very long.”
In general, the larger the artery and the smaller the extent of the blockage, the greater the likelihood that a technique such as angioplasty will be successful over the long term; for smaller vessels and lengthier sections of blockage, bypass is usually the better option. Factors such as a patient’s expected lifespan and overall health are also considered.
“If someone has other health issues, we want to try to do more minimally invasive procedures,” Forbes says, explaining that they’re less risky than open bypass. “If someone is more healthy, we may look at the most durable procedure. It’s a bit of a balancing act.” Both types of procedures pose a small risk for heart attack, stroke, or death, with the odds of death from surgery running between one and three per cent—though the actual magnitude of the risks depends on a patient’s overall health. Forbes says success for these procedures is measured by the percentage of arteries that would still be open in five years: “That would be 75 to 80 per cent with a bypass, and less than that with balloons and angioplasty.”
As Pat Garry grew more frustrated that he couldn’t do the things he wanted to do, his wife, Mary, a nurse, suggested he return to the specialized clinic—a vascular flow clinic—to explore his options. The doctor recommended an angiogram, which revealed two blockages. Whether to have bypass surgery was left up to Garry; he decided to go ahead.
Almost a month to the day after surgery, Garry, having weathered a few complications (including surgical bleeding severe enough to require transfusion and a problem with the incision healing) and with his legs and feet still swollen, commented, “I can wear flip-flops—barely.”
Today, he reflects: “I wasn’t prepared for the extent of the recovery. I mean, I had my first golf tee-off time booked in the summer and I fully expected I was going to be playing, but I’ve had to put my clubs away for the year.” (Still, to others contemplating non-emergency surgery, he recommends scheduling the operation for the summer months, if possible: “That’s the time of year to recuperate, not February. During summer, you can walk around on the deck or go out in the driveway.”)
While he estimates that it may be a little while before he’s able to climb two flights of stairs with ease, there’s every reason to believe that once his healing is complete, he’ll be able to resume a regular exercise program. This, along with the other steps he took to control his risk factors prior to surgery, should help him continue to lead a healthy, active life.
What You Don’t Know…
If you’ve never heard of peripheral arterial disease (PAD), you’re not alone: a 2006 survey (conducted for the non-profit PAD Coalition) of 501 Canadians over age 50 revealed that two out of three respondents were unfamiliar with the condition. And even among those who were aware of PAD:
- 42% didn’t know that smoking is a risk factor for the condition;
- 49% didn’t know that diabetes increases the chances of getting PAD;
- about half were unaware that hypertension and high cholesterol are risk factors;
- 20% didn’t realize that PAD is associated with an elevated risk for problems such as stroke and heart attack; and
- only 6.7% knew that PAD can lead to diminished walking ability or disability.