What is Critical Limb Ischemia?
Critical limb ischemia (CLI) refers to severe blockage of the arterial blood flow in both upper and lower limbs. It is an advanced stage of Peripheral Artery Disease (PAD). There is progressive worsening of the condition due to thickening of the arterial inner lining by a fatty substance which blocks the blood flow and is commonly known as atherosclerosis.
What are the Risk Factors of Critical Limb Ischemia?
Listed below are some of the known risk factors:
- Smoking and tobacco use
- Alcohol consumption
- Family history of peripheral artery disorders
- Sedentary Lifestyle
- High blood pressure
- High cholesterol
- Chronic Kidney disorders
- Sub clinical inflammation
Pathophysiology of Critical Limb Ischemia
Fatty deposits in the inner layer (endothelium) of the blood vessels, called plaque, leads to narrowing of the arteries and veins. The plaque obstructs the blood flow to the tissues and causes vasoconstriction impairing endothelial homeostasis. This cycle of impairment continues until plaque accumulates and triggers inflammation resulting in critical limb ischemia.
Signs and Symptoms of Critical Limb Ischemia
Common signs and symptoms of critical limb ischemia are as follows:
- Ischemic rest pain-a typical sign of CLI, is severe pain and soreness in the limbs even at rest
- Numbness and discoloration of the skin (Reddish, bluish, or greenish appearance)
- Dry, thickened skin
- Absent or minimal pulse sensation
- Shiny, taut skin and hair loss on the extremity
- Non healing ulcers
- Gangrene and infections
- Cold hands and feet
- Burning sensation that worsens at night
- Muscle wasting
Stages of Critical Limb Ischemia
The stages of critical limb ischemia are:
- STAGE 1: Asymptomatic or mild symptoms
- STAGE 2: Claudication (cramping pain due to reduced blood flow)
- STAGE 3: Ischemic rest pain
- STAGE 4: Ulcer or gangrene
Diagnosis of Critical Limb Ischemia
Your doctor may evaluate your medical history and perform a physical exam for signs and symptoms of the condition. If any findings are relevant, then your doctor may ask for additional tests as follows:
- Ankle-Brachial Index(ABI)- A result of less than 0.5 index confirms diagnosis and indicates severe CLI.
- Doppler Ultrasound, CT angiography, MR angiography techniques are used to assess the anatomical location of the occlusion in the blood vessels.
Differential Diagnosis of Critical Limb Ischemia
Other conditions that need to be ruled out to confirm a diagnosis of critical limb ischemia include:
- Night Cramps - Calf muscle pain that is relieved after taking anti-spasmodic and muscle relaxants.
- Diabetic neuropathy - Pain and burning sensation in the limbs which does not relieve even after reclining.
- Arthritis - Pain in the night which gets relieved by standing and medications. This pain is distinguished by uneven interval of occurrence.
Management of Critical Limb Ischemia
Early diagnosis increases the likelihood of effective treatment. The various options for treatment of CLI include the following;
- Medications- Your doctor may prescribe medicines for contributing factors such as pain medications, anti-hypertensive, anti-diabetics, anti-septic, anti-coagulants and statins to inhibit the progression.
- Lifestyle changes like quitting smoking, limiting alcohol consumption, avoiding excess fatty and fried foods as well as being more active and exercising regularly.
- Surgical intervention is required in patients observed with stage 3 and 4 ischemia such as:
- Angioplasty with or without stent – This is a minimally invasive endovascular procedure that widens the narrowed arteries and clears the arterial occlusions using a small, flexible tube or catheter with a balloon in the end.
- Amputation – This is a radical surgical measure for removal of the necrotic part of the limbs or extremities such as fingers, toes, leg etc to preserve the healthy parts. It is done in cases when there is no possibility of revascularization by any other techniques or complete tissue death is observed.
- Bypass grafting – This is the surgical replacement of the damaged artery by collateral formation.
- Laser atherectomy – This involves plaque vaporization using a laser probe.
- Direct atherectomy- This involves using a cutting blade directed towards the arterial wall through a catheter to remove the plaque.
What if Critical Limb Ischemia is Left Untreated?
If left untreated critical limb ischemia could result in the following complications:
- Cardiovascular diseases leading to severe cardiac emergencies
- High risk of amputation
- Sepsis shock
- Ischemic stroke
Prevention of Critical Limb Ischemia
- Risk of critical limb ischemia can be reduced by:
- Regular exercise and yoga practice
- Healthy diet and food habits
- Maintain normal blood pressure, sugar levels and cholesterol with proper medications
- Healthy weight
- Regular wound dressings and proper care
There must be lifelong follow-up for maintenance of nutritional status and post-surgical rehabilitation. A careful evaluation with blood tests and imaging studies periodically will help to identify any restenosis changes that can be managed effectively.