Peripheral arterial disease
Peripheral arterial disease (PAD) is a common and debilitating condition.
The age-adjusted prevalence of peripheral arterial disease is ~12% 3.
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.
The risk factors for PAD are basically the same as for coronary artery disease:
- diabetes mellitus
- cigarette smoking
- advancing age
- 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
- 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
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 ≤5cm in length
- single popliteal stenosis
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
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
May show calcified atherosclerotic plaques along the vessels.
Non-invasive technique and most widely used as the first step in any patient with cluadication 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.
Another noninvasive 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.
MR angiography is a noninvasive technique that can be acquired without contrast administration, however, sometimes it can overestimate stenosis severity.
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