How to Recognize and Treat Critical Limb Ischemia Early

Introduction

If your lower limbs ache during rest at night, it can be more than just fatigue. Know about the early signs of critical limb ischemia and prevent life-altering complications. 

Critical Limb Ischemia (CLI) is characterized by severe blockage of the lower extremities’ arteries that markedly reduces blood flow. The problem is a serious form of peripheral arterial disease (PAD) that is caused by atherosclerosis (plaque disposition on arterial walls leading to irregular blood flow). 

CLI is related to chronic pain in the feet or toes while resting. The problem is associated with poor blood circulation in lower limb extremities and non-healing wounds. Often, Critical Limb Ischemia (CLI) goes unnoticed with early sign appearance. At an advanced stage, the consequences get serious and can potentially lead to limb amputation. 

Ask The Expert

What are the Causes & Risk Factors of CLI?

CLI develops progressively and is largely associated with atherosclerosis, metabolic disorders and lifestyle factors. Critical Lower Limb Ischemia ICD 10​ is majorly coded under Category 170 (atherosclerosis). The causes include:

• Atherosclerosis: Primary cause of CLI. plaque builds up in the leg or foot, which significantly reduces blood flow. This leads to leg ache or cramps due to severe restricted blood flow. Several body tissues die, and the wound healing becomes impossible.
• Diabetes: Accelerates build up of plaque and increases amputation risk. Ulcers of gangrene on toes and heels appear, and wound healing becomes restrictive. 
• Hypertension: Elevated systolic pressure significantly increases aortic stiffness
• Lifestyle Factors: Smoking, Obesity, sedentary lifestyles, etc. increases risk of inflammation, damage to blood vessels, and increases CLI complexity. 

What are Signs & Symptoms of CLI?

The most common feature of CLI involves rest pain. Other early signs and symptoms include:

• Pain experience of numbness in the lower limbs
• Toenail thickening
• Shiny, dry, or smooth skin on the feet
• Diminished pulse on lower limbs
• Development of open sores, ulcers, or gangrene on the feet that do not heal
• Change in skin color (purple, black or green) due to tissue death

How is CLI Classified?

Critical Limb Ischemia Criteria are classified as:

Rutherford Classification

• Class IV: Rest pain 
• Class V: Minor Tissue Loss
• Class VI: Major Tissue Loss (Gangrene)

Fontaine Classification

• Class III: Rest pain
• Class IV: Severe tissue loss and Gangrene development

Threatened Limb Classification System (TLCS)

• Involves risk stratification based on wound size, ischemia and foot infection (WIfI) [1]

*At present, TLCS is the most appropriate classification system for clinicians. It considers the multispect cause of CLI development.

How is CLI Diagnosed?

Clinicians will do various physical examinations and laboratory assessments for CLI diagnosis. This includes:

• Ankle-Brachial Index (ABI): Comparison of arms vs. ankle pressure
• Toe Brachial Index: Comparison of arms vs. toe pressure
• Pulse Volume Recording: Measure blood flow volume changes in the legs
• Doppler Ultrasound: Velocity and direction of blood flow through blood vessels
• Angiography: X-ray imaging procedure to gain a 3D image
• MRI: Develops a 2-D or 3-D image of the blood vessels, revealing the blockage area of the blood vessels

What are the Treatment Options for CLI?

CLI diagnosis requires immediate attention to re-establish blood flow in the affected area. The options include:

Endovascular Treatment 

Involve minimally invasive options to combat artery blockage. The treatment recommendation depends on location and symptom severity. Endovascular procedure for CLI treatment includes:

• Angioplasty: Involves inserting tiny balloons via a puncture in the groin to open the blockage. The procedure can be either cutting balloon (microblade with balloon inserted with saline solution), or cryoplasty (nitrous oxide is used instead of saline solution)
• Stents: introducing a metal mesh ring or tube that expands the artery
• Laser Atherectomy: A small plaque bit that is vaporized by the laser tip
• Directional Atherectomy: Insertion of a catheter with a cutting blade that physically removes plaques

Surgical Treatment

• Involves bypass surgery, vein is grafted from the patient’s other body part or a synthetic graft. Recommended when endovascular treatments are not feasible

Medication

• Anticoagulants or antiplatelet drugs for reducing the risk of blood clot formation
• Statins for reducing bad cholesterol
• Antihypertensive medication to combat hypertension

Stem Cell Therapy for CLI: An Emerging Option

Mesenchymal stem cells (MSCs) isolated from umbilical cord blood/tissue, bone marrow and adipose tissue are widely studied for Critical Limb Ischemia Treatment. Stem cells’ key mechanism of action involves:

• Cellular Differentiation: MSCs are capable of differentiating into endothelial cells that form the inner lining of the blood vessels. They also differentiate into other cell types.
• Paracrine Signaling: MSCs release various growth factors (FGF2, IL-8, VEGF), cytokines, and chemokines in the damaged microenvironment. This induces a repair mechanism and the formation of naive blood vessels (angiogenesis)
• Arteriogenesis and Angiogenesis: Enhance new blood vessel formation and aid in the expansion of the existing vessels. They aid in distal perfusion restoration. 
• Immunomodulation: MSCs modulate immune reactions and reduce inflammation significantly. They promotes M2 macrophage polarization and secretes factors like PGE2, TSG6, and sTNFR

Clinical Application of Stem Cells in CLI patients

Although stem cell therapy is still too early, researchers have moved the treatment from the bench to the bedside. For CLI treatment, stem cell transplantation alone showed prominent challenges with immune response, compromised therapeutic efficacy, and hypoxia at the injury site. To combat such challenges, researchers launched collagen hydrogels for forming porous, 3D scaffolds. Collagen is a natural component in extracellular matrices; they enable self-assembly and interaction with collagen receptors on stem cells. 

Microgel constructs injected in mouse models with CLI showed increased blood perfusion rate by 40% and limb salvage ratio by 60% [2].

The success of the Stem Cell Therapy for Critical Limb Ischemia patients is still at an early stage. In the future, there is a need to launch large-scale clinical trials to ensure the safety, tolerance, and efficacy of the therapy. 

*NOTE: Preclinical and clinical evidence reflects safety and tolerance of stem cell therapy in CLI patients. The quality of stem cells plays a crucial role in therapy success and efficacy. Advancells, India, is a leading stem cell research-based laboratory that isolates and maintains superior quality stem cells for various chronic conditions, including CLI. 

When to See a Doctor?

We recommend to pay early visit to the doctor if you notice the following signs:

• Persistent rest pain in your leg or feet, increased pain at night
• Non-healing ulcer, gangrene, sores, or wounds
• Skin discoloration (bluish, pale, or dark)
• Weaker pulses on lower limbs, numbness, etc.

Conclusion

CLI is a critical limb condition that can lead to amputation. Don’t consider the persistent resting pain as mild discomfort. Seeking early medical attention is the key to prevention. It can restore adequate blood flow at an early disease development stage. We recommend that you remain proactive about your vascular health. Paying attention to early signs, managing metabolic conditions, and lifestyle factors are key to a quality of life.  

References

1. Shishehbor MH, White CJ, Gray BH, Menard MT, Lookstein R, Rosenfield K, Jaff MR. Critical limb ischemia: an expert statement. Journal of the American College of Cardiology. 2016 Nov 1;68(18):2002-15.
2. Drug Target Review. Novel 3D stem cell therapy to treat critical limb ischaemia [Internet]. 2024 Mar 14 [cited 2026 Apr 8]. Available from: https://www.drugtargetreview.com/novel-3d-stem-cell-therapy-to-treat-critical-limb-ischaemia/634367.article 

FAQ’s

Q- What is the Critical Limb Ischemia Definition?

Critical Limb Ischemia is associated with a chronic limb condition that is associated with resting pain in the lower limbs. The condition appears due to blockage of adequate blood flow in the legs or feet due to plaque formation.

Q- What is the Critical Limb Ischemia ICD 10 code?

Critical Limb Ischemia ICD 10 is coded within the category of I70 (atherosclerosis). 170.22 marks native arteries with chronic resting pain, 170.23-170.24 represent ulcer, and 170.26 represents gangrene. 

Q- Does Stem Cell Therapy Work for CLI?

Stem cell therapy for CLI is at an early stage. The preclinical and clinical evidence showed positive outcomes of the therapy in cellular regeneration, anti-inflammation, and pain management. The safety and tolerability of the therapy also remain intact.