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Etiology and pathophysiology

From the pathophysiologic point of view, a restriction of blood supply (ischemia) to the lower limbs can be classified as either functional or critical. Functional ischemia occurs when the blood flow is normal at rest but insufficient during exercise, presenting clinically as intermittent claudication. Critical ischemia is produced when the reduction in blood flow results in a perfusion deficit at rest and is defined by the presence of pain at rest or trophic lesions in the legs. In this situation, precise diagnosis is fundamental, as there is a clear risk of limb loss if adequate blood flow is not re-established, either by surgery or endovascular therapy. Differentiating between the two concepts is important to establish the therapeutic indication and the prognosis in patients with PAD.