Acute Limb Ischemia

Acute limb ischemia (ALI) occurs when there is a sudden interruption of blood flow through blood vessels of the arm or leg. In most cases, flow is blocked by a thickened mass of blood or clot. Such a blockage prevents necessary oxygen and nutrients from reaching cells and tissue that depend on them for survival. It also causes a buildup of harmful cell waste. How long tissue remains viable or “alive” depends on the degree to which a vessel is blocked as well as the presence of alternate vessels through which blood can flow to reach at-risk tissue. ALI could be an indication that an individual has long-standing peripheral artery disease, a narrowing of blood vessels due to a build-up of fatty deposits.

ALI can occur due to the following events:

  • Acute thrombosis occurs when a blood clot (thrombus) forms at the site of plaque build-up (atherosclerosis) in an artery. Thrombus is the most common cause of ALI, as it accounts for more than 80% of cases in the legs and about half of cases in the arms.
  • Arterial embolism occurs when a blood clot (embolus) breaks off from elsewhere in the body, such as the heart, travels through the bloodstream, and becomes lodged in an artery.

IMPORTANT NOTE: This overview is provided for informational purposes only and should not be used as a substitute for talking with your doctor. Be sure to talk with your doctor for a complete discussion of this condition as well as the benefits and risks of any treatment options.


  • pain
  • pulselessness
  • numbness (occurs in about half of patients)
  • pale color
  • paralysis
  • inability to regulate temperature (cold sensation)


Your doctor may:

  • ask you or a family member about your medical history, such as claudication (limping due to leg pain), diabetes, smoking, heart disease, palpitations, atrial fibrillation, and previous ischemic symptoms
  • ask about your signs and symptoms and when they began
  • conduct a neurologic examination focusing on sensory and motor function, which is critical for determining the level of ischemia and the urgency of intervention

Your doctor may order one of more of the following tests:

  • Ultrasound imaging uses sound waves to produce pictures of the structures inside the body
  • Computed tomography (CT) scan is an imaging test that uses a combination of X-rays and computer technology to produce images of the body. CT with contrast, a dye-like substance, enhances the image of the organ or tissue under study.
  • Magnetic resonance angiography (MRA) uses a powerful magnetic field, radio waves and a computer to evaluate blood vessels and help identify abnormalities or diagnose atherosclerotic (plaque) disease
  • Catheter angiography uses a catheter, X-ray imaging guidance and an injection of contrast material to examine blood vessels in key areas of the body for abnormalities such as aneurysms and disease such as atherosclerosis (plaque). Catheter angiography produces very detailed, clear and accurate pictures of the blood vessels.


Treatment for this condition must always be discussed with your doctor
for a full discussion of options, risks, benefits, and other information.

Treatment of a threatened limb is time critical, as irreversible damage can occur within 4 to 6 hours from the time an artery becomes blocked by clot. Immediate endovascular or surgical removal of the clot is recommended in order to restore blood flow to the limb and prevent amputation.

Endovascular treatment consists of one or a combination of two basic approaches to restore proper blood flow: 1) an injection of a clot-busting drug, and 2) mechanical thrombectomy, a minimally-invasive procedure that physically removes clot from blocked arteries