Vascular Surgery

Acute Limb Ischaemia

Sudden arterial occlusion cuts limb perfusion faster than collaterals can compensate, so nerve and then muscle fail within hours and the limb is lost unless flow is restored.

Definition

Acute limb ischaemia is a sudden fall in arterial perfusion that threatens the viability of the limb, conventionally with symptoms of less than two weeks' duration. The usual causes are embolism, in-situ thrombosis on existing arterial disease, and occlusion of a bypass graft or stent. Severity is graded clinically with the Rutherford classification.

First principles

Acute loss of flow is a different disease from chronic peripheral arterial disease

Acute limb ischaemia (ALI) means arterial symptoms of less than two weeks' duration. An embolus, thrombosis of a diseased artery, or occlusion of a graft or stent shuts off flow before collateral vessels can enlarge. Chronic disease has had months to build collaterals, which is why a chronically ischaemic leg tolerates an occlusion that would threaten a previously healthy one.

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