INTRODUCTION AND DEFINITIONS
Eight to ten million Americans suffer from arterial occlusive disease, with approximately 500 to 1,000 new cases of chronic limb ischemia per million per year . Patients with critical ischemia present with rest pain, which is pain across the base of the metatarsal heads at rest relieved by dependency, or with tissue loss, which can be ulceration, dry gangrene or wet gangrene, occurring in the lower extremities due to atherosclerotic occlusive disease of the iliac, femoral or popliteal arteries . Signs of critical limb ischemia on noninvasive testing include an ankle-brachial index less than 0.4, a flat waveform on pulse volume recording, and low or absent pedal flow on duplex ultrasonography .
The different therapies for critical limb ischemia will be reviewed here, according to the site of the vascular lesion and the specific clinical setting. The clinical manifestations and diagnosis of this disorder and acute limb ischemia are discussed separately. (See "Overview of acute arterial occlusion of the extremities (acute limb ischemia)".)
Limb-threatening ischemia occurs in 1 to 2 percent of patients with PAD who are 50 years of age or older . The natural history of critical limb ischemia usually involves inexorable progression to amputation unless there is an intervention that results in the improvement of arterial perfusion. This is in contrast to the often benign natural history of mild and moderate claudication. (See "Clinical features and diagnosis of lower extremity peripheral artery disease".)
The ACC/AHA practice guidelines suggested the following distribution of outcomes at one year in these patients [2,3]:
●Alive with two limbs – 50 percent