Chronic Lower Limb Ischemia: An Overview

Introduction:

Chronic limb ischemia causes deformity of the limbs, followed by perishing vascular supply. This condition can turn out to be a life-threatening condition if the limbs turn non-viable. Almost 1.3 percent of the adult population suffers from chronic limb ischemia. The severity can progress into a life-threatening disorder within five years of diagnosis.

What Is the Difference Between Intermittent Claudication and Critical Limb Ischemia?

• Intermittent Claudication: Claudication is a pain in the leg and foot radiating up to the buttocks due to blocked peripheral arteries of the lower limb. It is caused due to lifestyle disease. The patient experiences pain in the lower leg while exercising and is pain-free at rest.

• Critical Lower Limb Ischemia: It is caused due to ulceration or gangrene in the foot or toes. The patient complains of extreme pain and may be on regular painkillers. Critical lower limb ischemia is also known as a limb-threatening disease.

How Does Chronic Lower Limb Ischemia Occur?

Diseases of the peripheral artery system affecting the lower extremity, like legs and feet, occur due to the narrowing of the arteries. It causes reduced blood flow. Certain diseases like atherosclerosis can also trigger peripheral artery disease. During exercise, there is an imbalance between oxygen supply and oxygen need. This eventually leads to oxygen-deprived cells and produces excessive lactic acid and P substance. Such anaerobic metabolism paves the way for pain in the legs. The greater the obstruction, the greater will be the pain.

Risk Factors:

• Tobacco use.

• High blood pressure.

• High cholesterol.

• Atherosclerosis (plaque buildup in arteries).

• Diabetes can trigger chronic lower limb ischemia.

What Are the Common Symptoms Associated With Chronic Lower Limb Ischemia?

Some associated symptoms of intermittent claudication are:

• Pain while exercising can cause difficulty walking and may lead to limping.

• The more the pain, the greater the level of arterial obstruction.

• Pain in the buttock area is an indication of aortoiliac disease. It is associated with Leriche’s syndrome and is more common in men. This occurs in thirty percent of the population.

• Pain in the thigh region indicates the involvement of the femoral artery or aortoiliac disease. It covers the upper two-thirds portion of the calf. It is seen in sixty percent of claudication cases.

• Pain in the calf region refers to superficial femoral or popliteal artery disease. This involves the lower one-third of the artery.

• Foot pain indicates involvement of tibial or peroneal artery disease. It involves the posterior part of the leg.

Symptoms caused due to critical lower limb ischemia are:

• The patient experiences extreme pain in the lower limb while resting. For example, in bed. The pain subsides while the foot is against the ground. It is also known as - the cry of a dying nerve. It may be caused due to ulceration or gangrene of the foot. This pain is constant and occurs at the foot.

What Are the Tests Conducted to Examine Chronic Limb Ischemia?

A thorough physical examination is required to assess the extent of claudication. Some of the methods of physical examination are:

• Inspection: Changes are seen on the skin's surface, like brittle nails, hair loss, ulceration or gangrene, and immobile or weak muscles.

• Palpation: The complete absence of arterial pulse indicates critical ischemia. And the presence of a partial pulse of intermittent claudication.

• Auscultation: If a bruit is heard at the periphery artery, it represents stenosis of the blood vessels.

• Response to Exercise: Exercise helps in identifying arterial stenosis. During exercise, the pulse rate decreases.

• Temperature: Patients with chronic ischemia have low body temperature in the extremities or cold legs.

• Buerger's Angle of Vascular Insufficiency: This test is done to check the pallor of the foot while raising the foot to forty centimeters. A complete absence of color due to poor capillary circulation indicates critical limb ischemia.

• Dependent Rubor: During advanced stages, the color of the foot changes to dark red.

• Lerich’s Syndrome: In impotent males, the pain radiates up to the buttocks.

• Ankle Brachial Pressure Index (ABPI): The ratio of systolic blood pressure of the ankle is checked over the systolic blood pressure of the brachial artery of the arm. The resting ABPI is 1.0, and values below 0.9 indicate claudication. A value less than 0.5 suggests pain and values less than 0.3 indicate tissue death.

Other investigations of choice are:

• Duplex Scan: This is a gold standard test. It helps in detecting the site and rate of obstruction of blood flow.

• Digital Subtraction Angiogram (DSA): This test is done preoperatively and is a road map for surgery. The computer subtracts the bone and soft tissues and captures obstructed arteries.

• Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) Angiograms: can be useful where a duplex scan is impossible.

What Are the Various Types of Chronic Limb Ischemia?

According to Rutherford’s classification, chronic limb ischemia is classified into seven different categories. They are:

i.) Category 0: The patient will have no symptoms.

ii.) Category 1: The patient may experience very few symptoms.

iii.) Category 2: The patient may experience moderate levels of claudication.

iv.) Category 3: During this stage, the patient will experience severe claudication followed by pain.

v.) Category 4: The patient will have pain during rest.

vi.) Category 5: The leg may have ulcers or abrasions on the surface.

vii.) Category 6: The patient develops severe ischemic ulcers like gangrene.

What Is the Treatment for Chronic Limb Ischemia?

Depending upon the grade of obstruction, the treatment is carried out. They are:

• Lifestyle Modification: If the patient has moderate symptoms and pulse is noted in intermittent claudication, specific lifestyle changes can bring changes like quitting smoking, limiting physical exertions, and controlling diabetes, blood pressure, and cholesterol levels.

• Medical Management: Administration of drugs such as Pentoxifylline 400 mg or Cilostazol A phosphodiesterase III inhibitor helps against claudication distance.

• Revascularization Surgery: A surgical procedure like percutaneous transluminal angioplasty (PTLA) is done for localized atheroma. Extensive atheroma bypass surgeries like iliofemoral, femoropopliteal, or femoral-tibial bypass surgeries are conducted.

• Amputation: Depending on the level of gangrene, amputation is done. For example, Ray's amputation for toe gangrene, trans-metatarsal amputation, Syme’s amputation, and below-knee amputation.

Conclusion:

A prompt evaluation should be made for chronic limb ischemia, and the patient should be relieved of pain and rest. A good history should be noted. Non-invasive vascular lab tests and duplex scans should be conducted every three to six months. The duplex test is carried out twice a year if the condition improves.