Peripheral Artery Disease (PAD)
Peripheral artery disease (PAD, also called peripheral arterial disease) is a circulation problem, where clogged arteries can limit blood flow. More than 200 million adults worldwide (and 10 million Americans) are affected by PAD, including up to 20% of people >70 years old. It is believed to be significantly underdiagnosed, especially in women. Smoking (whether current or past) is the strongest risk factor associated with PAD; other risk factors include high blood pressure, diabetes, high cholesterol, age >50 years old, and race/ethnicity.
PAD and Atherosclerosis
PAD is most commonly an expression of atherosclerosis, often called “hardening of the arteries.” With atherosclerosis, cholesterol is deposited on the inside of arteries; as that layer gets thicker, the artery gets harder, stiffer and more narrow. Atherosclerotic plaque (atheroma) can reduce blood flow over time and most frequently affects the heart, brain, and legs. Being diagnosed with PAD increases the likelihood that a person also has heart disease and/or carotid stenosis. We often recommend that PAD patients be screened for these other problems.
Up to 40 percent of people with PAD have no symptoms, but the most classic symptom of PAD is a type of leg pain called claudication. Arterial claudication is a pain that predictably occurs in a muscle group (most often the calf, but sometimes the thigh or buttock) after walking a certain distance and goes away after a few minutes of sitting or standing still. Typically, the pain is described as a muscle ache, tightness, weakness or tiredness. It comes on more easily when walking quickly or uphill. Most people with claudication can often do other forms of exercise, such as riding a bike, using an elliptical machine, or swimming, without getting the same kind of leg pain.
In up to a third of people with PAD the artery blockages can continue to grow to the point where blood flow to the leg is reduced enough to lead to non-healing wounds, gangrene, or pain in the foot that occurs even when at rest in bed. This level of disease is called critical limb-threatening ischemia (CLTI), is more likely to happen in active smokers, and means that the person could lose part of the leg if blood flow is not improved.
Diagnosis of PAD
The first step in diagnosis involves taking a good history of patient symptoms and doing a physical examination (including feeling or listening for pulses at the wrists and feet). Simple testing can be done using ultrasound and blood pressure measurements of the arms and legs to confirm the diagnosis. Additional imaging may be recommended such as CT scan and angiography.
Take our quick quiz to see if you may be at risk for PAD.
Treatment of PAD
Treatment always starts with aggressively managing any risk factors that may be contributing (ie. No smoking, lowering cholesterol level, controlling diabetes, increasing activity level, etc). Many times a supervised, structured walking program and medication are enough to improve symptoms. If that does not result in more normal activity levels, angiography is usually recommended next. During an angiogram, the surgeon inserts a small catheter into an artery in the groin, and the patient is injected with contrast dye, which makes areas of artery narrowing visible on continuous X-ray (fluoroscopy).
With various tools and techniques, we can often open up the artery blockages and increase blood flow through the artery. Angiography can be performed under a local anesthetic with sedation in the operating room or radiology. These procedures can take 1-3 hours, with another 2-4 hours of bedrest in the recovery area, where you are watched for any signs of bleeding or other immediate problems. Risks of angiography include bleeding from the hole where the catheter goes into the body, unintended injury to the inside of the artery, and causing new clots or blockages in the artery that were not there before. Almost all patients can be discharged home on the same day.
Angioplasty
Angioplasty is a technique during angiography that uses a special catheter with a balloon at one end. The balloon catheter is positioned through the area of blockage, and the balloon is inflated, spreading the plaque so that it has a bigger opening and there is more room for blood flow.
Stent
Stents are metal mesh tubes made in the size of blood vessels to hold a vessel open, whether because the vessel is clogged with plaque or scar tissue or if it is being squeezed by something on the outside of the vessel. Stents can be self-expanding (the metal has “memory” of how big it is supposed to be, and the metal will always try to reach that size) or balloon-expandable (the metal tube is “loaded” onto a balloon catheter, and when the balloon is inflated, the stent is also opened up to the same size as the balloon).
Other tools/devices available include:
- Drug-coated balloon or stent - the balloon or stent is treated with a special drug which is then transferred to the vessel wall to block the regrowth of plaque and scar tissue
- Intravascular ultrasound – catheter with a miniature ultrasound probe on the tip to look at and measure the layers of the vessel, including plaque and blood clot
- Thrombectomy catheters – catheters designed for the removal of blood clots
- Cutting balloon – balloon with several lines of micro-blades designed to make controlled cuts in the inner surface of vessel plaque or scar tissue
- Intravascular lithotripsy - balloon catheter that sends sound waves through the artery to selectively break calcium plaque into fragments
- Atherectomy - catheter with a cutting or sanding surface on the end that rotates very fast (ie. 70,000 rotations per minute) to shave and make a bigger opening through plaque
Bypass Surgery
Sometimes whatever is causing a blood vessel to be blocked cannot be opened from inside the vessel, or perhaps it was able to be opened using minimally invasive techniques but then closed up again within a short time. At that point, we would consider bypass, which in most situations lasts longer than any of the minimally invasive procedures described above. Bypass surgery reroutes blood around areas of blockage, usually an artery; bypass can also serve to replace an artery that has an aneurysm. A bypass graft (or “bypass”) is a long tube made of polyester material or polytetrafluoroethylene, a waterproof material. Sometimes we can use a piece of vein from the patient's own body as the bypass graft. The graft is tunneled through the involved body part (bypass can be done anywhere on the body) and sewn to the artery above the blockage and the artery below the blockage to create a detour around the blocked segment.
A bypass can involve two, three or multiple incisions and can take two to five or more hours depending on what body part is being treated and whether or not a patient’s own vein will be used as a graft. Bypass surgery is performed under general anesthesia or a spinal anesthetic (medicine injected into the back to make the legs temporarily numb). Hospital stay with bypass varies by the body part treated but on average ranges from two to seven days. Risks of bypass surgery include: heart attack, bleeding, skin or graft infection, slow healing of incisions, and long-lasting swelling.
Post-Operative Expectations
After both bypass and angiography, patients are monitored with ultrasound scans, which help to detect any re-narrowing in the arteries or the bypass, or the development of new blockages elsewhere. Early identification of developing problems allows for prompt treatment if necessary and maintenance of good blood flow. Certain medications have been shown to optimize outcomes in vascular surgery - these are aspirin (baby or 81mg) and statin (a type of cholesterol-lowering medicine). Unless there are specific reasons that a patient cannot take these, all patients who have had a procedure or operation done on an artery should be on aspirin and statin. Additional medications may be prescribed to further thin the blood depending on the situation.
Regular walking exercise is recommended both before and after an arterial procedure. Smoking is absolutely discouraged - in fact, tobacco use is known to significantly increase the chances of the operation failing early with plaque continuing to develop even with medications. Maintaining good control of risk factors (watching blood pressure and cholesterol, managing diabetes, not smoking) maximizes the chances of long-term success for both bypass and angiography.