Clinical Pearls & Morning Reports
Published July 11, 2018
Chronic limb-threatening ischemia represents the end stage of peripheral arterial disease and is associated with a high risk of limb amputation. Read the lastest Clinical Practice Article here.
Q: How is chronic limb-threatening ischemia defined?
A: Chronic limb-threatening ischemia, a manifestation of peripheral arterial disease that is characterized by chronic, inadequate tissue perfusion at rest, is associated with decreased quality of life and substantial morbidity and mortality. In contrast to acute limb ischemia (severe limb hypoperfusion of <2 weeks in duration), chronic limb-threatening ischemia (also called critical limb ischemia, chronic critical limb ischemia, or severe limb ischemia) is defined as ischemic pain in the foot while a person is at rest with pain lasting 2 or more weeks, nonhealing wounds, or gangrene that is attributable to objectively proven arterial occlusive disease.
Q: What percentage of patients with less severe peripheral arterial disease are estimated to have progression to chronic limb-threatening ischemia?
A: It is estimated that over a 5-year period, 5 to 10% of patients with asymptomatic peripheral arterial disease or intermittent claudication will have progression to chronic limb-threatening ischemia.
A: Chronic limb-threatening ischemia is suspected in patients with atherosclerotic risk factors who have characteristic pain, tissue loss, or both in the distal leg or foot. Ischemic pain occurs at rest and affects the foot; some patients have numbness rather than pain. The pain is worse with elevation and lessens with dependency (placement of the foot lower than the level of the heart). Symptoms typically develop in patients who are in bed, and relief may be obtained by dangling the affected foot. Physical examination is typically notable for an absence of ankle pulses, dependent rubor, thin or shiny skin, an absence of hair, and increased capillary-refill time. Tissue loss usually affects the toes, although the heel, ankle, and even calf may be involved. The severity of ischemia can be assessed by a battery of noninvasive vascular tests, including measurement of ankle pressures and toe pressures, pulse-volume recordings, and Doppler waveforms, commonly performed together at the same sitting. Transcutaneous oxygen measurements are useful in identifying severe ischemia and provide prognostic information regarding wound healing and the likelihood of healing after amputation. When treatment is planned, duplex ultrasonography, computed tomography, or magnetic resonance angiography is recommended to gain information about the location and extent of occlusive disease; the latter two studies are particularly useful to evaluate proximal, aortoiliac occlusive disease.
A: A cornerstone of treatment is timely arterial revascularization, without which the rates of limb loss approach 40%. Surgical and endovascular revascularization are currently used to treat chronic limb-threatening ischemia. Surgical revascularization with the use of bypass has been the standard strategy for the treatment of chronic limb-threatening ischemia. Infrainguinal bypass is the most commonly performed bypass in patients with chronic limb-threatening ischemia; success rates vary according to the type and quality of conduit used. Whereas polytetrafluoroethylene, polyester, arm vein, small saphenous vein, composite autogenous vein, and cryopreserved saphenous vein are used for bypass, the best outcomes have been reported with single-segment great saphenous vein. High surgical risk, limited life expectancy, inadequate autogenous vein, minor tissue loss, limited occlusive disease (stenosis or short occlusions), and lack of a suitable bypass target vessel favor endovascular revascularization. Otherwise, bypass is preferred. Physician training, preference of the patient, and physician and center expertise also factor into decision-making.