What Is Critical Limb Ischemia?

Critical limb ischemia (CLI) is a condition involving significantly reduced blood flow to the lower extremities. It affects 12% of the U.S. population. The cause of CLI is a severe blockage of the arteries from a condition called peripheral artery disease (PAD). In fact, CLI is considered the most severe form of PAD.

Critical Limb Ischemia Symptoms

The cardinal signs of CLI include severe pain in the feet and toes (even when at rest) as well as necrosis (death) of tissue. Other signs and symptoms may include:

• Poor circulation in the lower extremities
• Ulcers and wounds in the legs and feet that do not heal
• Pain or numbness in the feet
• Thickening of the toenails
• Shiny, smooth, dry skin of the feet and legs
• Diminished or absent pulses on the feet or legs
• Gangrenous tissue of the feet or legs

Causes

CLI is considered the final stage of PAD, a chronic, progressive thickening of the arterial wall resulting from the buildup of plaque, a fatty, waxy substance. The plaque occludes normal blood flow, resulting in a lack of proper oxygen in the tissues, also referred to as ischemia. PAD can reduce blood flow in the hands, legs, or feet, but CLI usually involves just the legs and feet. 

Risk Factors

The risk factors that may cause a person to be more prone to CLI are the same as those for PAD. These include:

• Smoking
• Advanced age
• Diabetes
• Obesity or being overweight
• Sedentary lifestyle
• High cholesterol levels
• Hypertension (high blood pressure)
• Family history of atherosclerosis

Diagnosis

Diagnosis of CLI may involve one or more tests or assessments, including:

• Audible presence of a bruit: A stethoscope is used to listen for bruits, turbulent vascular blood flow, in the affected arteries of the legs.
• Ankle-brachial index (ABI): Blood pressure cuffs are positioned at the ankle and the upper arm. The systolic pressure recorded at the ankle is divided by the systolic pressure at the arm to determine the ABI, which can help assess blood flow or detect blockage in the legs and the risk for an adverse cardiovascular event.
• Doppler ultrasound: A type of ultrasound that creates a picture using sonography to measure how strong the blood flow is through the blood vessels.
• Computed tomography angiography (CT angiography: An advanced imaging technique that uses an intravenously injected contrast dye to view arteries and veins in parts of the body. Three-dimensional images of the blood vessels are then created.
• Magnetic resonance angiography (MRA): A type of magnetic resonance imaging (MRI) that is specifically focused on the blood vessels (including arteries). An MRA is much less invasive—and less painful—than traditional angiography, which requires the insertion of a catheter.
• Angiography: X-rays of the blood vessels—including the arteries—are taken after inserting a long, flexible catheter to deliver dye into the blood vessels. The use of contrast dyes helps the vessels show up better on the X-ray image.

Treatment

Treatment for CLI is aimed at restoring blood flow to the affected area. Treatment may include several different types of interventions, including:

Endovascular Procedures

There are several types of endovascular procedures to help improve blood flow through the arteries.

The type of procedure used depends on several factors, such as the severity and location of the blockage. Some common types of endovascular surgery include:

• Angioplasty: A very small balloon is inserted into the artery through a catheter. It is then inflated using saline solution, which can help move plaque outward, toward the wall of the artery, restoring blood flow.
• Stents: Metal mesh tubes are positioned where an artery is blocked. The stents serve as a support for the walls of the artery, keeping it open so that blood can flow through.
• Atherectomy: A catheter with a rotating cutting blade is inserted into arteries to remove plaque, opening the blood vessel and allowing blood flow to resume. This procedure is an alternative to angioplasty.

Surgical Treatment

When endovascular surgery is not an option, such as when arterial blockages occur in an inaccessible location, surgical treatment may be necessary.

Treatment of wounds and ulcers (to remove dead or infected tissue due to poor blood flow) also may be needed.

Prognosis

CLI is associated with a very high risk for adverse medical events such as:

• Heart attack
• Amputation
• Death

In fact, a 2018 study revealed that within the first year of being diagnosed with CLI, 29% of patients will either need a major amputation or they will not survive.

Studies show that intensive follow-up for those with atherosclerosis helps extend people's life expectancy.

Coping

There is a very high rate of depression and other psychological issues experienced by people with CLI. Reasons include:

• The condition often interferes with a person’s ability to be active.
• The condition may force a person to depend on others to meet their daily needs.
• Most people with CLI cannot work.
• CLI is a long-term condition, involving intensive medical treatment, surgery, long-term rehabilitation, and multiple visits to outpatient medical facilities.

If you have CLI, you may need to empower yourself with information. The more you are involved in your own treatment choices, the more empowered you will feel. Self-empowerment can help you cope with feelings of helplessness.

It’s also vital to reach out for help when you need it. Ask for support from friends and family members when possible. Joining a support group for people with PAD and CLI can be a very effective tool in dealing with some of the depression and isolation that often go hand in hand with the disease.

A Word From Verywell

If you have been diagnosed with CLI, it's important to note that intensive long-term care is an absolute necessity after treatment. Follow-up care includes rehabilitation to help you return to your maximal level of physical activity and independence. 

Although the statistics may look grim when it comes to the outcome of CLI, there is hope. Those who follow a strict regimen of follow-up care—according to their doctors' instructions—are able to beat some of the odds, improving their prognosis and even extending their life expectancy after treatment.