Overview: Peripheral Arterial Disease
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Peripheral arterial disease (PAD) is commonly caused by atherosclerosis, which is a build-up of plaque deposited in the walls of blood vessels. These plaques are made of cholesterol, fatty substances, calcium, and other products which can cause the arteries to become stiff and narrowed. This can eventually lead to decreased or completely blocked blood flow to the arms and legs.
The risk factors for developing PAD are similar to those for coronary artery disease (CAD). Those at highest risk for developing PAD are those with diabetes (even borderline) or who have a history of smoking. Many people who suffer with PAD either have diabetes and/or have smoked at some point in their lives. Some people may not even know they have diabetes until they undergo a special blood test to check for it.
Other risk factors for developing PAD include high blood pressure, high cholesterol, kidney disease or CAD. As we age, the likelihood of having PAD also increases.
Signs & Symptoms
Like chest pain that occurs when blood flow to the heart muscle is compromised, the leg muscles may exhibit symptoms when blood flow is reduced. Claudication—leg cramps in the muscles that occur with activity and improve with rest—occurs because of inadequate blood flow to the leg muscles, such as those in the calf and thighs. Although claudication is the classic symptom of PAD, most will complain of more subtle symptoms such as heaviness in the legs, weakness, or a feeling that the legs may give out.
Standing and resting for a few minutes will cause the symptoms that stopped someone from walking to resolve, as the muscles need less oxygen and nutrition while at rest. While it is safe to begin to walking again, the same cycle of discomfort with walking that resolves with rest will continue.
Over time, people with PAD tend to: limit what they do in order to avoid symptoms, walk slower, or even use a cane. However, they may improve their symptoms by attempting to walk through them.
In its early stages or with mild PAD, there may be minimal physical exam findings. Pulses may be faint or even absent. PAD, when advanced, may be associated with hair loss on the legs and toes, color changes in the skin, loss of feeling and coolness. The skin can become dry and thin over time. Maintaining skin integrity and moisture is important to prevent breakdown, which can be a source of infection.
The color of the skin can vary. It may be pale or appear pink when in a dependent position but can turn white when raised. Dark purple or black areas may develop on the toes when the skin is so deprived of oxygen and nutrients from reduced blood flow that it is dying. Sores can form and can have a difficult time healing when blood flow is minimal, raising the risk of infection. Both sores and infections can threaten the limb if medical attention is not sought.
There are a number of factors that predispose individuals to development or progression of peripheral arterial disease (PAD)—the build-up of cholesterol plaque (otherwise known as atherosclerosis) in the arteries. These include, but are not limited to:
- Older age: The chances of getting PAD increase significantly after age 40, and even more so after 70. Almost 1 in 25 persons older than 40, 1 in 7 over 70, and 1 in 4 over 80 have PAD.
- Smoking: Smoking is the most important modifiable risk factor for the development of PAD. It significantly increases risk of PAD, even more than having coronary artery disease (CAD). A person who smokes can get PAD 10 years earlier than a nonsmoker. Smokers have a risk of PAD that is four times that of nonsmokers. Furthermore, smokers have poorer survival rates and a greater likelihood of developing non-healing wounds, which can develop when stable PAD progresses to critical limb ischemia. Critical limb ischemia is a state where oxygen supply to the leg is inadequate to heal a wound, or prevent new wounds or amputation. Smokers have more re-blockage after arteries are cleaned out, and less success after bypass surgery when compared with nonsmokers.
- Diabetes: Diabetes increases the risk of developing PAD by up to four times and leads to an increased risk of cardiovascular events and early death. Almost 30% of PAD patients have diabetes or impaired blood sugar (glucose) tolerance—a precursor to diabetes. Diabetes (and poor foot care) is the most common cause of amputation in the United States. If you have uncontrolled diabetes, it increases your risk for PAD and progression of PAD more than controlled diabetes. Therefore, diabetes control is very important.
- Hypertension: High blood pressure is strongly associated with development of atherosclerosis in general, and PAD in particular. As many as 90% of patients with PAD have hypertension.
- Dyslipidemia/abnormal cholesterol: In the Framingham Study, an elevated cholesterol level was associated with twice the risk for chronic leg pain. According to the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey (NHANES), more than 60% of patients with PAD had hyperlipidemia. Meanwhile, the PARTNERS (PAD Awareness, Risk, and Treatment: New Resources for Survival) program found that three quarters of patients with PAD had high cholesterol levels. The higher the cholesterol level, the higher the risk of developing PAD and coronary artery disease. Treating high cholesterol may reduce risk for PAD progression.
- Ethnicity: African Americans and Hispanic females have higher prevalence of PAD than their Caucasian counterparts.
- Family history: Family history of premature atherosclerosis in first degree relatives is also a risk factor for PAD.
- Metabolic syndrome: Metabolic syndrome (the combination of obesity, high cholesterol, high blood pressure, and high blood sugar) increases the risk for PAD, as it does for coronary artery disease.
- Other risk factors: Chronic kidney disease and high levels of certain blood markers of inflammation (C-reactive protein, Beta-2 microglobulin, cystatin C, lipoprotein(a) and homocysteine) have also been associated with increased risk of PAD.
Anyone with symptoms or signs of peripheral arterial disease (PAD) should be tested. Some people should be screened for PAD even in the absence of symptoms or signs, such as individuals older than 65 years, or those older than 50 with risk factors like diabetes or smoking.
The diagnosis of PAD begins with a simple examination by your doctor or podiatrist. They will look at the skin on your legs and feet for color changes, ulcers, or wounds that may be slow to heal. They will also feel the temperature of your skin and check the pulses in your legs and feet to evaluate blood flow. Your doctor will also ask you questions about how active you are able to be and if you have any limitations. Your medical record will be reviewed to assess additional risk factors you have for PAD. Blood tests looking for signs of diabetes, kidney disease and high cholesterol may be performed.
If your doctor suspects you have PAD, then they will likely arrange for you to have an Ankle-Brachial Index test (ABI). This is a simple, non-invasive test that can be done in the office to evaluate circulation in the legs. It consists of taking blood pressure in the arms and at the ankles with an ultrasound probe. The exam takes about 10 minutes to perform and you will be asked to rest flat. After the two blood pressure readings, a ratio is then calculated to get the value of your ABI. A normal ABI ranges from 0.96–1.39. An ABI of 0.90 or less is considered indicative of PAD and the lower the number, the more severe the impairment in blood flow. An ABI of greater than 1.3 may represent stiff arteries that may or may not be blocked. Further information is needed to make a determination of PAD in this case.
Special waveforms may also be recorded during the examination that can reflect the quality of blood flow. They are obtained with a Doppler probe, or through a recording that is made when a blood pressure cuff is inflated at a low level in your ankle. Your physician will look at this waveform, your ABI number, and other information to make a determination of PAD. This test is very reliable. If your doctor needs more information, however, they may have you get a similar test which includes blood pressure readings and waveforms from your thigh down to your big toe. You may even be asked to walk on a tread mill while readings are performed before and after exercise.
In some cases, a CT or MRI may be required—usually where the ABI or ultrasound tests have detected an abnormality that requires further clarification for diagnostic purposes, or to guide the best treatment options. Finally, if any of the above non-invasive tests have revealed a significant abnormality, you may undergo an invasive, catheter angiogram which can serve as both a test and a treatment. This procedure involves injecting contrast dye into the affected arteries, and taking X-ray images to see where blockages may be located. If blockages are detected, they may choose to open these arteries up during the procedure by using a device designed to cut, drill or shave through the plaque, or displace it to allow more blood flow to get through. Many of these devices are similar to those used in the heart to open up blockages.
It is essential to learn about factors that may place you at risk for developing peripheral arterial disease (PAD) as you age. Addressing these risk factors may not only reduce the likelihood of developing PAD but may significantly lower your risk of stroke and heart attack. Many of these risk factors can be addressed through lifestyle modifications while others may require intervention with medications.
- Exercise regularly: Physical activity can lead to weight loss and improve your fitness level. A general guideline is to perform 30 minutes of cardio exercise, five days a week. If you can do it daily and make it a habit, that is even better.
- Avoid tobacco products: If you are a smoker, ask your doctor about ways to quit. There are many programs and products that can help you.
- Monitor your weight: If you are overweight or obese, consult with your doctor about a healthy weight loss program which includes a healthy diet and exercise.
- Eat healthy: A healthy diet is an essential part of any program to help prevent cardiovascular disease. A healthy diet consists of multiple servings of fresh vegetables, fruits, whole grains, lean meats, low-fat dairy and nuts. Avoid foods with solid fats, added sugars and refined grains. How you prepare your food is also very important. Avoid foods that are deep fried in oil or prepared with shortening or butter. Try to eat foods containing omega-3 fatty acids such as tuna, salmon, almonds and walnuts.
- Control blood pressure: Check your blood pressure regularly, avoid salt and take medication if your doctor advises it.
- Lower cholesterol: Addressing abnormal cholesterol with diet and/or medication could help in reducing plaque build-up. You have to check your cholesterol level by having a blood test.
- Treat elevated blood sugar (diabetes): Having your doctor check and monitor your blood sugar may also help you maintain healthy circulation.
While some factors cannot be controlled, including family history, age, race and gender, it remains important to focus on the factors that can be modified. If you are at risk, your doctor may look for other less common risk factors including chronic kidney disease, or elevated levels of C-reactive protein or homocysteine (so-called "inflammatory markers") in the blood.
Last but not least, it is critical to take good care of your feet and legs. Inspect them regularly and keep the skin soft with lotions. Be careful with toe nail clipping, wear comfortable, well-fitted shoes and see a podiatrist if you have any concerns about or if you have multiple risk factors for developing PAD.
Patients living with peripheral arterial disease (PAD) must be aware of several things. Because of blockages or decreased blood flow to leg muscles, feet and toes, these body parts must be protected. Blood not only heals, but it maintains health by providing oxygen and nutrients to the skin, cells and muscles.
If decreased blood flow leads to a small sore or ulcer, this can become a big problem with slow and poor healing, leaving a door open to infection, the development of a chronic, non-healing ulcer and even potential amputation if gangrene (skin/tissue death) occurs. Therefore, it is recommended that if you have PAD, you never walk barefoot, wear proper fitting shoes and examine your feet daily for any redness, sores or areas of concern.
You may need to use a mirror to see the soles of your feet or have a family member assist. Feel all around the foot for bumps, sores or tenderness. Seeing a podiatrist on a regular basis may also be advised depending on how advanced the PAD is and what risk factors are present.
In PAD, circulation is decreased due to the buildup of plaque in the arteries. This buildup is made up of primarily cholesterol, calcium and other debris. This is the same disease process that blocks the arteries in the heart (causing heart attacks), neck (causing strokes) and elsewhere. If you have PAD, you have a much higher risk of also having blockages in other arteries throughout the body that can lead to heart attack and stroke. It is recommended that you discuss your own individual risk for these potential consequences with your doctor.
Your doctor may want to perform an ECG, a stress test, or even a Doppler ultrasound depending on your history. PAD is treated medically to help reduce the risk of a heart attack or stroke, as well as slow any progression of PAD. Medications may also preserve your ability to be active, stabilize blockages already present and try to make the blood flow as efficient as possible. You should not smoke and you should eat a low-fat, low-cholesterol, heart-healthy diet.
PAD can also slowly rob you of your ability to be active. Your muscles need oxygen and blood to work, provide strength and balance. If blood flow is limited, so is your ability to be active. You may notice various symptoms of claudication, such as heaviness in your legs or intense cramping while walking a certain distance or at a particular speed.
If you feel you are limited in what you can do, or have noticed a decrease in how far or fast you can walk, your circulation may have worsened and you should speak to your doctor. At more advanced stages of PAD, rest pain can occur when your legs are elevated at night due to extremely poor blood flow and the lack of gravity to assist with circulation. If you have rest pain, it will occur most nights and can severely compromise your activity level.
In summary, if you find you’ve had a decline in function (e.g., less active or able to keep up), it could be due to development or progression of PAD. While there is no cure for PAD, you can lessen your risk of consequences by taking prescribed medications, maintaining a healthy lifestyle, staying active, not smoking, and knowing when to address any issues that may arise.
Being well-informed can keep you a step ahead of peripheral arterial disease (PAD). In addition to this resource on CardioSmart.org, you can learn more by visiting:
Published: Nov. 2015
Medical Contributors & Reviewers: Mirvat Alasnag, MD, BCh, King Fahd Armed Forces Hospital; Anne Albers, MD, FACC, Ohio Health; Herbert Aronow, MD, MPH, FACC, Brown University; Wobo Bekwelem, MD, University of Minnesota Hospital & Clinics; Neal Bhatia, MD, Emory University School of Medicine; Jaafer Golzar, MD, FACC, Advocated Christ Medical Center; Keyur Mavani, MD, Community Medical Center and Moses Taylor Hospital; Khusrow Niazi, MBBS, FACC, Emory University; Andrew Roy, MD, ICPS; Michelle Sloan, NP, Eastlake Cardiovascular Associates; Suthipong Soontrapa, MD, Texas Tech University.