Peripheral arterial disease (PAD) is a common and debilitating condition.
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Epidemiology
The age-adjusted prevalence of peripheral arterial disease is ~12% 3.
Pathology
Atherosclerosis is the leading cause of occlusive arterial disease of the extremities in patients over 40 years of age with the highest incidence in the sixth and seventh decades of life.
Risk factors
The risk factors for PAD are basically the same as for coronary artery disease:
cigarette smoking
advancing age
overweight/obesity
Classification
Rutherford classification
stage 0: asymptomatic
stage 1: mild claudication
stage 2: moderate claudication - the distance that delineates mild, moderate and severe claudication is not specified in the Rutherford classification but is mentioned in the Fontaine classification as 200 meters
stage 3: severe claudication
stage 4: rest pain
stage 5: ischemic ulceration not exceeding ulcer of the digits of the foot
stage 6: severe ischemic ulcers or frank gangrene
Fontaine classification
stage I: asymptomatic.
-
stage II: intermittent claudication
stage IIa: intermittent claudication after more than 200 meters of pain free walking
stage IIb: intermittent claudication after less than 200 meters of walking
stage III: rest pain
stave IV: ischemic ulcers or gangrene
TASC II classification of femoral and popliteal lesions
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type A lesions
single stenosis ≤10 cm in length
single occlusion ≤5 cm in length
-
type B lesions
multiple lesions (stenoses or occlusions), each ≤5 cm
single stenosis or occlusion ≤15 cm not involving the infrageniculate popliteal artery
single or multiple lesions in the absence of continuous tibial vessels to improve inflow for a distal bypass
heavily calcified occlusion ≤5 cm in length
single popliteal stenosis
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type C lesions
multiple stenoses or occlusions totalling >15 cm with or without heavy calcification
recurrent stenoses or occlusions that need treatment after two endovascular interventions
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type D lesions
chronic total occlusion of the common or superficial femoral artery (>20 cm, involving the popliteal artery)
chronic total occlusion of the popliteal artery and proximal trifurcation vessels 4
Radiographic features
Plain radiograph
May show calcified atherosclerotic plaques along the vessels.
Ultrasound
Non-invasive technique and most widely used as the first step in any patient with claudication pain, particularly the ankle brachial index. B-Mode ultrasonography can evaluate the arterial wall as well as the luminal stenosis by measuring diameter and surface area reduction.
Atheromatous calcification in the arterial wall can be seen as hyperechoic foci and when large causes acoustic shadowing.
Doppler study can estimate stenosis by measuring the difference in blood peak systolic velocity pre- and post-stenosis.
Stenosis grading
A common adopted grading system (initially proposed by Cossman) uses the pre-stenosis to stenosis velocity ratio and is as 5
<1.5:1 = normal
1.5-2:1 = 25-50% stenosis
2-4:1 = 50-75% stenosis
> 4:1 = > 75% stenosis
no flow = occluded
CT
Another non-invasive technique is CTA, which utilizes intravenous contrast medium injection to opacify the arterial lumen and detect any change in the caliber. Assessment of the stenosis, occlusion and collateral circulation can be done using multislice thin axial cuts followed by multiplanar reconstruction. Maximum intensity projections (MIP) and volume rendering techniques (VRT) can also be used in the assessment of the vessels.
MRI
MR angiography is a noninvasive technique that can be acquired without contrast administration, however, sometimes it can overestimate stenosis severity.
DSA
Digital subtraction angiography is an invasive technique done percutaneously through femoral catheter insertion. It is the gold standard for assessment of stenosis, occlusion and collateral flow and can be diagnostic and therapeutic.
Treatment and prognosis
Primary treatment strategy according to TASC severity:
TASC A: endovascular therapy
TASC B: endovascular therapy
TASC C: surgical therapy (if the patient is fit for surgery, otherwise endovascular therapy)
TASC D: surgical therapy