angiography), mra scans (magnetic resonance angiography), or ultrasounds for imaging. in the setting of symptoms consistent with peripheral artery disease a physician will then examine an individual for specific exam findings. abnormal physical exam findings can lead a health care provider to consider a specific diagnosis. however, in order to confirm a diagnosis, confirmatory testing is required. these findings are associated with peripheral artery disease: decreased or absent pulses muscle atrophy or wasting noticeable blueness of the affected limb decreased temperature (coolness) in affected limb when compared to the other thickened nails smooth or shiny skin and hair loss buerger's test can check for pallor when the affected limb is in an elevated position. the limb is then moved from elevated to sitting position and is checked for redness, which is called reactive hyperemia. buerger's test is an assessment of arterial sufficiency, which is the ability of the artery to supply oxygenated blood to the tissue that it goes to. nonhealing lower extremity wound if peripheral artery disease is suspected, the initial study is the ankle–brachial index (abi). the abi is a simple, non-invasive test, which measures the ratio of systolic blood pressure in the ankle to the systolic blood pressure in the upper arm. this is based on the idea that if blood pressure readings in the ankle are lower than those in the arm, a blockage in the arteries that provide blood from the heart to the ankle is suspected. an abi range of 0.90 to 1.40 is considered normal. a person is considered to have pad when the abi is ≤ 0.90. however, pad can be further graded as mild to moderate if the abi is between 0.41 and 0.90, and severe if an abi is less than 0.40. these categories can provide insight into the disease course. furthermore, abi values of 0.91 to 0.99 are considered borderline and values >1.40 indicate noncompressible arteries. if an abi >1.40 is calculated, this could indicate vessel wall stiffness caused by calcification, which can occur in people with uncontrolled diabetes. abnormally high abis (>1.40) are usually considered false negatives and thus, such results merit further investigation and higher-level studies. individuals with noncompressible arteries have an increased risk of cardiovascular mortality within a two-year period. in individuals with suspected pad with normal abis can undergo exercise testing of abi. a baseline abi is obtained prior to exercise. the patient is then asked to exercise (usually patients are made to walk on a treadmill at a constant speed) until claudication pain occurs (for a maximum of 5 minutes), after which the ankle pressure is again measured. a decrease in abi of 15%–20% would be diagnostic of pad. if abis are abnormal, the next step is generally a lower limb doppler ultrasound to look at the site of obstruction and extent of atherosclerosis. other imaging can be performed by angiography, where a catheter is inserted into the common femoral artery and selectively guided to the artery in question. while injecting a radio-dense contrast agent, an x-ray is taken. any blood flow-limiting blockage found in the x-ray can be identified and treated by procedures including atherectomy, angioplasty, or stenting. contrast angiography is the most readily available and widely used imaging technique. modern computerized tomography (ct) scanners provide direct imaging of the arterial system. studies have shown the sensitivity and specificity of ct in identifying lesions with >50% stenosis as 95% and 96% respectively. as such, ct may be considered as an alternative to invasive angiography. an important distinction between the two is that, unlike invasive angiography, assessment of the arterial system with ct does not allow for vascular intervention magnetic resonance angiography (mra) is a noninvasive diagnostic procedure that uses a combination of a large magnet, radio frequencies, and a computer to produce detailed images of blood vessels inside the body. the advantages of mra include its safety and ability to provide high-resolution, three-dimensional imaging of the entire abdomen, pelvis and lower extremities in one sitting. classification gangrene of three toes resulting from peripheral artery disease the two most commonly used methods to classify peripheral artery disease are the fontaine and the rutherford systems of classification. the fontaine stages, were introduced by rené fontaine in 1954 to define severity of chronic limb ischemia: stage i: asymptomatic stage iia: intermittent claudication after walking a distance of more than 200 meters stage iib: intermittent claudication after walking a distance of less than 200 meters stage iii: rest pain stage iv: ulcers or gangrene of the limb the rutherford classification was created by the society for vascular surgery and international society of cardiovascular surgery, introduced in 1986 and revised in 1997 (and known as the rutherford classification after the lead author, robert b. rutherford). this classification system consists of four grades and seven categories (categories 0–6): grade 0, category 0: asymptomatic grade i, category 1: mild claudication grade i, category 2: moderate claudication grade i, category 3: severe claudication grade ii, category 4: rest pain grade iii, category 5: minor tissue loss; ischemic ulceration not exceeding ulcer of the digits of the foot grade iv, category 6: major tissue loss; severe ischemic ulcers or frank gangrene moderate to severe pad classified by fontaine's stages iii to iv or rutherford's categories 4 to 5, presents limb threat (risk of limb loss) in the form of critical limb ischemia. recently, the society for vascular surgery came out with a classification system based on "wound, ischemia and foot infection" (wifi). this classification system, published in 2013 was created to account for the demographic changes that have occurred over the past forty years including increased incidence of high blood sugar and evolving techniques and ability for revascularization. this system was created on the basis of ischemia and angiographic disease patterns not being the sole determinants of amputation risk. the wifi classification system is broken up into two parts: wounds and ischemia. wounds are graded 0 through 3 on the presence of ulceration and/or gangrene and ischemia. grade 0: no ulcer, no gangrene grade 1: small, shallow ulcer; no gangrene grade 2: deep ulcer with exposed tendon or bone, gangrene limited to toes grade 3: extensive, full-thickness ulcer; gangrene extending to forefoot or midfoot ischemia is graded 0 through 3 based on abi, ankle systolic pressure, and toe pressure. grade 0: abi ≥0.80, ankle systolic pressure ≥100 mm hg, toe pressure ≥60 mm hg grade 1: arterial brachial index 0.6 to 0.79, ankle systolic pressure 70 to 100 mm hg, toe pressure 40 to 59 mm hg grade 2: abi 0.4–0.59, ankle systolic pressure 50 to 70 mm hg, toe pressure 30 to 39 mm hg grade 3: abi ≤0.39, ankle systolic pressure <50 mm hg, toe pressure <30 mm hg the tasc (and tasc ii) classification suggested pad treatment is based on the severity of disease seen on angiogram. screening it is not clear if screening for disease in the general population is useful as it has not been extensively studied. this includes screening with the ankle-brachial index (abi), although a systematic review of the literature did not support the use of routine abi screening in asymptomatic patients. testing for coronary artery disease or carotid artery disease is of unclear benefit. while pad is a risk factor for abdominal aortic aneurysms (aaa), there is no data on screening individuals with asymptomatic pad for abdominal aortic aneurysms. in people with symptomatic pad screening by ultrasound for aaa is not unreasonable. treatment depending on the severity of the disease, these steps can be taken, according to these guidelines: lifestyle stopping smoking (cigarettes promote pad and are a risk factor for cardiovascular disease) regular exercise for those with claudication helps open up alternative small vessels (collateral flow) and the limitation in walking often improves. treadmill exercise (35 to 50 minutes, three or four times per week) has been reviewed as another treatment with a number of positive outcomes, including reduction in cardiovascular events and improved quality of life. supervised exercise programs increase pain-free walking time and the maximum walking distance in people with pad. medication management of diabetes management of hypertension management of high cholesterol, and antiplatelet drugs such as aspirin and clopidogrel. statins reduce clot formation and cholesterol levels, respectively, can help with disease progression, and address the other cardiovascular risks that the affected person is likely to have. according to guidelines, taking aspirin or clopidogrel is recommended to reduce ami ("heart attack"), stroke, and other causes of vascular death in people with symptomatic peripheral artery disease. it is recommended that aspirin and clopidogrel be taken alone and not in conjunction with one another (i.e., not as dual antiplatelet therapy). the recommended daily dosage of aspirin for treating pad is between 75 and 325 mg, while the recommended daily dosage for clopidogrel is 75 mg. the effectiveness of both aspirin and clopidogrel to reduce risk of cardiovascular ischemic events in people with symptomatic pad is not well established. research also suggests that low-dose rivaroxaban plus aspirin is effective as a new anti-thrombotic regimen for pad. cilostazol can improve symptoms in some. pentoxifylline is of unclear benefit. cilostazol may improve walking distance for people who experience claudication due to peripheral artery disease, but no strong evidence suggests that it improves the quality of life, decreases mortality, or decreases the risk of cardiovascular events. treatment with other drugs or vitamins are unsupported by clinical evidence, "but trials evaluating the effect of folate and vitamin b12 on hyperhomocysteinemia, a putative vascular risk factor, are near completion". revascularization after a trial of the best medical treatment outline above, if symptoms persist, patients may be referred to a vascular or endovascular surgeon. the benefit of revascularization is thought to correspond to the severity of ischemia and the presence of other risk factors for limb loss such as wound and infection severity. 3d medical animation still shot depicting the vascular bypass grafting angioplasty (or percutaneous transluminal angioplasty) can be done on solitary lesions in large arteries, such as the femoral artery, but may not have sustained benefits. patency rates following angioplasty are highest for iliac arteries, and decrease with arteries towards the toes. other criteria that affect outcome following revascularization are length of lesion and number of lesions. there does not appear to be long term advantages or sustained benefit to placing a stent following angioplasty in order to hold the narrowing of the subsartorial artery open. atherectomy, in which the plaque is scraped off of the inside of the vessel wall (albeit with no better results than angioplasty). vascular bypass grafting can be performed to circumvent a diseased area of the arterial vasculature. the great saphenous vein is used as a conduit if available, although artificial (gore-tex or ptfe) material is often used for long grafts when adequate venous conduit is unavailable. when gangrene has set in, amputation may be required to prevent infected tissues from causing sepsis, a life-threatening illness. thrombolysis and thrombectomy are used in cases of arterial thrombosis or embolism. guidelines a guideline from the american college of cardiology and american heart association for the diagnosis and treatment of lower extremity, renal, mesenteric, and abdominal aortic pad was compiled in 2013, combining the 2005 and 2011 guidelines. for chronic limb threatening ischemia the accf/aha guidelines recommend balloon angioplasty only for people with a life expectancy of 2 years or less or those who do not have an autogenous vein available. for those with a life expectancy greater than 2 years, or who have an autogenous vein, bypass surgery is recommended. prognosis individuals with pad have an "exceptionally elevated risk for cardiovascular events and the majority will eventually die of a cardiac or cerebrovascular etiology"; prognosis is correlated with the severity of the pad as measured by an abi. large-vessel pad increases mortality from cardiovascular disease significantly. pad carries a greater than "20% risk of a coronary event in 10 years". the risk is low that an individual with claudication will develop severe ischemia and require amputation, but the risk of death from coronary events is three to four times higher than matched controls without claudication. of patients with intermittent claudication, only "7% will undergo lower-extremity bypass surgery, 4% major amputations, and 16% worsening claudication", but stroke and heart attack events are elevated, and the "5-year mortality rate is estimated to be 30% (versus