Most predominant cause is atherosclerotic disease
Other causes include antiphospholipid syndrome, popliteal aneurysms, adventitial cystic disease, popliteal artery entrapment, and trauma.
Collateral circulation allows for blood flow to all areas of the lower extremity in the face of localized occlusive disease
Muscle arterial resistance can be decreased to allow a large increase in blood flow. This is physiologic during exercise and compensatory during ischemia
As occlusive disease progresses, it usually involves multiple sites in the lower extremity vasculature
The first symptoms are noted by the patient during exercise because the leg is no longer able to increase blood delivery in the normal fashion
Claudication, is reproducible lower extremity muscle pain on walking that is relieved by rest
Most commonly, it involves the calf.
As ischemia progresses, pain is encountered at rest.
With critical ischemia, the patient experiences rest pain and wounds are unable to heal, so that the patient is predisposed to infection, gangrene, and limb loss
Rest pain initially begins in the forefoot (metatarsalgia) and toes and progresses proximally.
Patients often notice a beneficial effect of gravity on their arterial blood flow.
Many let their legs hang over the side of the bed in a dependent fashion to increase the effect of gravity, which augments minimal perfusion and decreases pain.
Conversely, symptoms of rest pain are provoked and worsened when the extremity is elevated...
Useful in predicting the likelihood of wound healing
Amputations healed in all patients with an ABI above 70%
Healing did not occur in 25% of those with an ABI below 70%
Simple and inexpensive
In diabetics is often unreliable because of abnormal wall calcification and noncompressibility
Additional information can be obtained by measuring pressures at various levels of the lower extremity
Gradients of more than 20 mm Hg are diagnostic of a hemodynamically significant lesion
Exercise stress test can be performed...