The Advanced Stages of PAD
Part one of our three-part series on peripheral artery disease (PAD; pronounced P.A.D.) covered the early, sometimes symptom-free stages of PAD. PAD is a narrowing of the peripheral arteries serving the legs, stomach, arms and head. (“Peripheral” in this case means away from the heart, in the outer regions of the body.)
PAD most commonly affects arteries in the legs. Whether or not a person shows symptoms, if they have atherosclerotic plaque in their extremities, technically they have PAD. Often accompanied and made worse by diabetes, identifying PAD early and doing everything in one’s power to treat it and slow the progression is key. As we covered in part one, this entails making healthy lifestyle changes first and foremost — especially not smoking! — and may also involve medication.
In this, the second part of our series, we’re discussing what happens when PAD progresses to more advanced stages, presenting obvious symptoms that affect a person’s quality of life.
How does PAD get worse?
Dr. Anotonio Gutierrez
Like coronary artery disease, PAD is caused by atherosclerosis. Atherosclerosis is the buildup of plaque (fatty deposits) in the arteries. As plaque builds up, blood vessel walls thicken, narrowing the passage and reducing blood flow. This means less oxygen and nutrients making their way to parts of the body.
As cardiologist Antonio Gutierrez, assistant professor of medicine at Duke Medical School shared in part one, “You can definitely slow the progression by quitting smoking, taking cholesterol medication and starting to exercise. There are some people that that’s all they need. PAD is very hard to reverse, but you can slow it down.”
But when progression isn’t slowed, PAD can become disabling and, in the worst cases, may even require amputation.
When PAD becomes critical
When a person experiences the following due to known blockage in a peripheral artery, their PAD has resulted in critical limb ischemia (CLI):
- Two or more weeks of having pain or cramping when at rest
- Nonhealing wounds, ulcers or gangrene in one or both legs
Patients with CLI often have other forms of severe cardiac or cerebrovascular disease. Diabetes, smoking, old age and chronic kidney disease are the most common risk factors for the development of advanced PAD and CLI.
Smoking is associated with a three-fold increase in the risk of developing CLI and the risk of developing
CLI increases proportionally to the number of cigarettes smoked. Diabetics have a four-fold increase in the risk of developing CLI when compared with nondiabetics.
Diagnosis of CLI combines tests that identify the disease in an artery along with an examination of visible symptoms and information from the patient about how severely symptoms are affecting their quality of life. CLI is a chronic condition, meaning it is persistent or constantly recurring.
Most people with PAD will not end up having CLI. (We discussed the treatment options for those who don’t in part one of this series.) For those who do advance to this stage, there are ways to restore better blood flow that may be considered. (See Improving the Flow section below.)
When PAD becomes an emergency
Acute limb ischemia (ALI) is a medical emergency that needs to be identified rapidly. Gutierrez explained, “If somebody’s having a myocardial infarction (heart attack), they go straight to the cath lab so we can see what’s going on. You have an equivalent of that in the leg and that is acute limb ischemia.” ALI may be caused when a plaque abruptly breaks, a blood clot forms, and the blood flow to the leg is suddenly blocked, “They lose pulses, and their leg is extremely painful — those are people you take directly to the cath lab.”
Time is of the essence because it only takes about four to six hours for skeletal muscle to be seriously damaged by the lack of blood flow. The medical team must quickly assess the degree of damage to the limb as well as whether there is a chance to restore blood flow. The longer pain and loss of function in a limb goes on, the more the limb is threatened. When a limb goes without blood flow for too long, it may require amputation.
ALI may be caused by underlying PAD, but it can also be caused by trauma, a tear in the artery wall or other conditions that cause blood clots. It is potentially devastating, but at the same time, it is one of the most treatable presentations of PAD. Timely recognition of an artery blockage resulting in a cold, painful leg is crucial to successful treatment. A catheter or surgical procedure may be performed to get rid of the blood clot causing the blockage. The degree of damage to the limb along with other factors help determine which procedure to perform.
Improving the flow
The goal for those with CLI is to minimize tissue loss, heal wounds and make sure the foot gets the blood it needs to work properly. There are several minimally invasive catheter-based procedures that may be considered. Techniques such as angioplasty and stents continue to evolve with different types of balloons and stents available to choose from on a case-by-case basis.
When a patient receiving treatment for PAD (including structured exercise therapy) has persistent, lifestyle-limiting pain or cramping, it’s reasonable to consider procedures to improve blood flow. There are several of them. What’s best for a patient depends on the specifics of their situation. The medical team and the patient will work together to explore options and determine what’s best in their case.
“Although patients will often have disease in both legs, usually we’ll start by treating the leg causing the most problems,” said Gutierrez.
Angioplasty involves threading a wire through the artery to a blockage. A balloon is then inserted and delivered to the area where plaque is causing a problem, also referred to as a lesion. “As the balloon inflates, it basically pushes all the plaque to the side,” Gutierrez said. Most patients are home within 24 hours of the procedure.
But angioplasty may not last forever — how long the artery will stay open is hard to predict. “Every patient is different. Some people get an angioplasty, and it’ll last several years. Others last a few months,” Gutierrez said. “It all depends on how bad their disease is, their risk factors, if they quit smoking, if they have diabetes. I’ve had patients where I balloon a lesion and don’t see them back for years.”
When a lesion is harder (more calcified), has been in place for a long time or is lengthy, angioplasty may not get the job done. In that case, atherectomy may be an option — another catheter procedure that removes plaque from the artery.
A stent is a wire mesh tube inserted into an artery to prop it open, allowing blood flow. They may be used in those cases mentioned above when angioplasty doesn’t last, and the vessel narrows again. “It pushes everything to the side and keeps the artery from re-collapsing on itself,” Gutierrez said.
Stents don’t work well in spots where flexibility is required. “The stent is like a little tube made of chicken wire,” said Gutierrez. “It’s not very flexible and if you bend it, it stays kinked. There are certain areas like behind the knee or right at the hip joint where you don’t want to put a stent because if it bends, it’s not going to stay open.”
Gutierrez shares a potential downside: “You’re leaving a foreign object in the body, so the clock is ticking.” Stents can last for years, “if you’re lucky.” A lot depends on the patient. What other conditions are they managing? How far has the PAD progressed? How well are they following their medical advice and sticking to their preventive therapies? All of these variables make outcomes hard to predict.
For both angioplasty and stents, the after care is the same: “If somebody gets [sic] angioplasty or stents, we usually recommend they continue with aggressive, preventive therapy with aspirin and statin therapy,” Gutierrez said. In some cases, a prescription antiplatelet may also be prescribed for three to six months to prevent blood clots. “But this is on top of quitting smoking and exercising daily. Fortunately, new medical therapies are in the pipeline that will help reduce the risk of adverse events in patients with PAD.”
Catheter-based solutions may not be able to restore the necessary blood flow. When that is the case, bypass surgery may be an option. In most cases, peripheral artery bypass is performed on the legs, though it can also be done on the arms.
“Basically, it is a way to get blood from one artery to an artery farther down the leg in order to improve blood flow to relieve claudication pain or relieve an ulcer or wound that won’t heal,” said vascular surgeon Peter Henke, professor of surgery at the University of Michigan School of Medicine. “Wounds that won’t heal are a common indication of a problem.”
Typically, a blood vessel from another part of the patient’s body is used to “bypass” the diseased artery. But sometimes, a patient won’t have a vein that is viable for surgery. “If the patient doesn’t have any vein conduit, we can use a prosthetic vessel of either Dacron or more commonly
Dr. Peter Henke
of PTFE (Gore-Tex). However, prosthetic bypasses have two downsides: they tend not to last as long before failing and they can get infected, whereas vein grafts almost never get infected,” Henke said. After a bypass the old artery is left in place. It is already blocked off and can’t cause any harm. “It’s like scar tissue, it’s out of circulation and remains stable.”
Recovery time for bypass is about five days. “The first day, we get the patient up just a little bit to a chair or sitting up in bed,” he said. “The next day, they walk around in the room a little bit, and the next day they walk in the halls. Physical therapy is integrally involved to get them moving in the right direction.”
The doctors are monitoring pain, watching for infection, and making sure there’s no bleeding. “Anytime you work on an artery with a bypass, it could bleed,” he said. It also could cause a clot, “Though that is rare.”
After surgery, patients are put on an antiplatelet, like aspirin, as well as a statin. “In some cases where the bypass is going to a very diseased artery, what we call a high-risk bypass, meaning that we’re worried that it has a higher likelihood than usual to fail, we may put the patient on an anticoagulant such as warfarin or one of the newer anticoagulants such as rivaroxaban or apixaban,” Henke said.
Although bypasses, angioplasty and stents are all done to restore blood flow, they are used in different situations. Catheter-based options are effective for shorter areas of blockage, but sometimes a long length of artery is diseased.
Amputation — the last resort
Amputation is the outcome all the other interventions are meant to avoid. Henke says there are three situations that may result in amputation as relates to PAD.
The most common is the patient who has undergone multiple procedures to restore blood flow and has run out of options: “They’ve had an angioplasty and stent that has failed, and then a bypass that failed, and their disease has progressed,” Henke said. “There are some patients who have very bad tibial disease, meaning the arteries that go to the lower leg and foot are basically obliterated. We can’t do a bypass because there’s no target artery we can go to.”
Then there are emergency amputations: “Someone comes in with wet gangrene of the foot, very sick, they need to have that foot taken off, and then they usually get converted to a below-the-knee amputation,” he said.
Third are patients who are immobile because of severe dementia or a severe stroke. “For those patients who do not ambulate, rather than a bypass to save a non-functional limb, we’ll often do an amputation,” he said.
“We typically try to stay as far down the leg as we can, meaning we’ll start generally with a half-foot amputation if the blood flow is good enough to heal,” he said. “Those can be pretty functional. The patient still has their heel, and they just need a forefoot prosthesis in their shoe.”
The most common amputation is a below-the-knee amputation. “The prosthetic limbs now are much better than they were 20 years ago. They’re lighter and fit better,” Henke said. “We work very closely with physiatrists as well as physical and occupational therapists who make this much better for the patients. It’s really a team effort to get the patient back to being ambulatory — that is the goal.”
Generally, it’s about four to six weeks to heal the incision and remove staples and stitches. “I would say you’re talking at least two months total before they are ready for the prosthetic,” Henke said. “Sometimes, it’s longer than that if they don’t have good blood flow to heal that stump. It can be anywhere from two months to six months or even longer.” As with all procedures for PAD, aftercare includes antiplatelets and statins.
The silver lining of a PAD diagnosis
Although PAD is a sign of persistent atherosclerosis, most patients with PAD never need any type of procedure. “So, really, it’s a marker to prescribe best medical care,” Henke said. “Medical care includes antiplatelet therapy, a statin agent, good blood pressure control, not smoking and exercise. Patients who have PAD need to walk, swim or bike — anything to keep their legs active, which decreases the chance that their PAD will progress. Patients who stay on their medications and exercise mostly do very well and never need a revascularization procedure.
“Most of the patients we see are patients who have multiple issues including diabetes, maybe renal failure and are on dialysis, and continue to smoke. They end up with a non-healing ulcer, a gangrene, something that mandates a procedure, whatever that might be.
“I think a PAD diagnosis is somewhat optimistic in the sense that PAD, if it’s treated well, is a way to get patients on the right medications that decrease not only their limb-related issues but also their life-related issues, as these medications decrease their long-term chance of heart attack, stroke and death.”