Acute limb ischemia.

Although there is little information on the incidence of acute limb ischemia (ALI) in the general population, it is estimated to be 14 per 100,000 and to compose 10% to 16% of the vascular workload. Also, as surgical intervention has become an option for ALI, the numbers actually referred appear to be increasing. The two main causes of ALI are either an embolism or a thrombosis, and differentiation based on history and clinical examination alone may be clinically impossible in 10% to 15% of cases. However, with the advent of thrombolysis, the distinction between emboli and thrombotic occlusions has become less important from the point of view of management. The natural history of ALI has remained largely unchanged despite the advent of the Fogarty catheter and thrombolysis. Patients presenting with ALI continue to have a particularly severe short-term outlook both in terms of loss of the leg and mortality, with 30-day amputation rates of between 10% and 30% and a mortality rate of around 15%. A patient with an embolic cause for an ischemic leg is at a higher risk of death because of the associated underlying cardiac disease, whereas patients with a thrombotic cause are more likely to lose a limb. The fact that overall mortality rates after intervention for acute ischemia have not improved dramatically over the past 20 years no doubt reflects the severity of the underlying diseases in these high-risk patients.