Critical Limb Ischemia

Overview

Critical limb ischemia, also called chronic limb-threatening ischemia, is the most severe stage of peripheral artery disease. In peripheral artery disease, the arteries that carry blood to the legs and feet become narrowed or blocked. When the blood flow falls so low that the tissues are starved of oxygen even at rest, the limb is genuinely threatened.

This is a serious condition. Without restoring blood flow, it can lead to non-healing wounds, infection, and loss of tissue, and in some cases amputation becomes necessary. The good news is that prompt treatment to improve circulation can relieve pain, heal wounds, and save the limb. Because critical limb ischemia also signals widespread artery disease, it carries risks for the heart and brain too, so it needs comprehensive care.

Symptoms

The hallmark of critical limb ischemia is that symptoms occur even at rest, not just with walking. Warning features include:

• Rest pain: Aching or burning pain in the foot or toes, often worse at night or when lying flat, and eased by hanging the leg down
• Sores, ulcers, or wounds on the foot or toes that do not heal
• Areas of dark, black, or dying tissue (gangrene)
• A foot that is cold, pale, or bluish
• Shiny skin, hair loss, and thickened toenails on the affected leg
• Weak or absent pulses in the foot

Non-healing foot wounds and rest pain are signals to seek prompt medical care, before infection or tissue loss develops.

Causes

Critical limb ischemia almost always results from severe narrowing or blockage of the leg arteries, usually due to a buildup of fatty plaque (atherosclerosis). Contributing factors include:

• Atherosclerosis: The underlying process that hardens and narrows arteries over time.
• Diabetes: Accelerates artery disease and damages nerves, which can mask pain and worsen wounds.
• Smoking: A major driver of artery damage.
• High blood pressure and cholesterol: Speed up plaque buildup.
• Blood clots: A clot can suddenly worsen flow in an already narrowed artery.

Risk Factors

• Smoking, the single strongest risk factor
• Diabetes
• High blood pressure and high cholesterol
• Older age
• Existing peripheral artery disease or heart disease
• Chronic kidney disease

Diagnosis

Doctors assess both how severe the reduced blood flow is and where the blockages are:

• Examination: Checking pulses, skin, temperature, and any wounds on the foot.
• Ankle-brachial index: Comparing blood pressure at the ankle and arm to gauge blood flow.
• Ultrasound: Maps blood flow and finds narrowed segments.
• Angiography: CT, MRI, or catheter-based imaging shows the arteries in detail to plan treatment.

Because critical limb ischemia means widespread artery disease, evaluation of the heart and other vascular risks is also important.

Treatment

The central goal is to restore blood flow to the limb, along with treating wounds and the underlying artery disease. Care is led by a vascular specialist team.

• Restoring blood flow: Procedures to open or bypass the blocked artery, including angioplasty with or without a stent, or surgical bypass.
• Wound care: Treating ulcers, removing dead tissue, and controlling infection with antibiotics.
• Risk factor control: Stopping smoking, managing diabetes, blood pressure, and cholesterol, and using medicines to reduce clotting and protect the heart.
• Pain relief: Managing rest pain while treatment proceeds.
• Amputation: Reserved for when blood flow cannot be restored and tissue loss or infection threatens health; the aim is always to save as much limb as possible.

Prevention

• Do not smoke, and seek help to quit if you do
• Keep diabetes, blood pressure, and cholesterol well controlled
• Check the feet daily, especially with diabetes, and treat small wounds early
• Wear well-fitting footwear and avoid foot injuries
• Stay active as advised and attend vascular follow-up if you have peripheral artery disease

When to See a Doctor

Seek prompt medical care for foot or leg pain at rest, especially pain that wakes you at night and eases when you dangle the leg, or for any foot wound that is not healing. Seek urgent care if a foot becomes suddenly cold, pale, painful, and numb (which can mean a sudden blockage), or if a wound shows spreading redness, pus, or you develop fever, as infection in a poorly supplied limb can become dangerous quickly.

Related Topics

Frequently Asked Questions

References

1. National Heart, Lung, and Blood Institute (NHLBI). Peripheral Artery Disease.
2. Mayo Clinic. Peripheral artery disease (PAD) - Symptoms and causes.
3. MedlinePlus, U.S. National Library of Medicine. Peripheral artery disease - legs.
4. Centers for Disease Control and Prevention (CDC). Peripheral Arterial Disease (PAD).