Peripheral Arterial Disorders | Medical Science Optional Notes for UPSC PDF Download

Causes of limb ischemia

Large Artery Occlusion Causes

• Atherosclerosis (Chronic): Gradual buildup of plaque in arteries.
• Embolism (Acute): Sudden blockage caused by a traveling clot or debris.

Characteristics: Often feels cold and appears white due to decreased blood flow.

Small Artery Occlusion Causes

• Buerger's Disease (Chronic): A chronic condition affecting arteries, often linked to smoking.
• Raynaud's Disease (Acute): Acute episodes leading to blood vessel constriction triggered by cold or stress.
• Embolism (Acute): Sudden blockage by a clot or debris.
• Diabetes (Chronic): Chronic condition causing damage to small blood vessels.
• Scleroderma (Chronic): Chronic autoimmune disease affecting skin and blood vessels.
• Physical Agents (Acute): Trauma, radiation, electric burns, or pressure causing acute artery issues.

Characteristics: Manifestations vary depending on the specific condition, but they can include acute or chronic symptoms related to blood flow compromise.

Features of limb ischemia

• Intermittent Claudication:
  • Arises from anaerobic metabolism during physical activity.
  • Characterized by cramp-like pain occurring while walking, typically absent on the initial step.
  • Alleviated by rest within 5 minutes, whether in a standing or sitting position.
• Rest Pain:
  • Results from continuous anaerobic metabolism even during periods of rest.
  • Aggravated when lying down or elevating the foot due to reduced gravitational effects on foot perfusion pressure.
  • Typically more severe at night, with relief achieved by hanging the foot out of bed or sleeping in a chair.
• Ulceration:
  • Presents as shallow, painful erosions located between toes or as non-healing ulcers on the dorsum of the foot, particularly around the shins and malleoli.
• Gangrene:
  • Indicates advanced tissue death in the affected area.

Gangrene

Death of macroscopic portions of tissue, which turns black because of breakdown of hemoglobin and the formation of iron sulphide.

Signs of Gangrene

• Color alteration: Begins with a shift to pale or bluish-purple and eventually progresses to black.
• Temperature loss in the affected area.
• Sensation loss.
• Absence of pulsation.
• Impairment or loss of function in the affected area.

Management of Gangrene

• Considered to have an urgently threatened limb requiring immediate vascular assessment/intervention.
• Examination includes:
  • Checking Capillary refill time: Normal is 2-3 seconds, but severe ischemia leads to prolonged refill (>10 seconds).
  • Assessing arterial pulses in key locations.
  • Screening for aortic aneurysms and renal artery bruits through auscultation over pulses.

Investigations Required

(a) Confirming presence and severity of peripheral arterial disease.
(b) Identifying the specific location of the disease.
(c) Assessing patient suitability for intervention.

General Investigations for Surgical Suitability

• Complete Blood Panel (to rule out polycythemia).
• Blood sugar levels (for diabetic patients).
• Serum creatinine and Blood urea levels (essential for angiography).
• Lipid profile (especially in cases with concurrent coronary disease).
• Electrocardiogram (ECG) and 2D Echocardiogram.
• Arterial Blood Gas (ABG) or Pulmonary Function Tests (PFT) for chronic obstructive pulmonary disease (COPD) evaluation.

Special Investigations for Vascular Assessment

• Handheld Doppler Ultrasound Blood Flow Detection:
  • Normal artery exhibits a triphasic signal (forward flow in systole, reverse flow in late systole/early diastole, forward flow in late diastole).
  • Abnormal signals are biphasic or monophasic.
• Ankle Brachial Pressure Index (ABPI):
  • Ratio of ankle systolic pressure to ipsilateral arm systolic pressure.
  • ABPI range:
    • Normal: 0.9 to 1.3.
    • Claudication: <0.9.
    • Rest pain: <0.5.
    • Imminent necrosis: <0.33.

• Duplex Scanning:
  • B-mode ultrasound with color coding for vessel images.
  • Color indications:
    • Blue: Flow away from the transducer.
    • Red: Flow towards the transducer.
    • Lighter shades represent higher velocity.
    • Green or yellow signifies high flow turbulence or stenosis.
  • Safe and cost-effective compared to angiography but challenging for visualizing the AORTOILIAC SEGMENT.
• Digital Subtraction Percutaneous Angiography (DSA):
  • Involves injecting radioactive dye via percutaneous catheter for diagnosis and therapy.
  • Potential complications: Bleeding, hematoma, false aneurysms, thrombosis, arterial dissection, distal embolization, renal dysfunction, allergic reactions.
• Newer Techniques:
  • CT Angiography and MR Angiography have slightly inferior image quality compared to DSA.

Management and Treatment

• Control modifiable risk factors like hypertension (avoid beta-blockers exacerbating claudication), hyperlipidemia (use of statins), smoking, and diabetes mellitus.
• Antiplatelet therapy (Aspirin or Clopidogrel) is recommended as per NICE guidelines.
• Structured exercise program (minimum 2 hours per week for 3 months) improves claudication distance.
• Consider invasive treatment when:
  • ABPI is deteriorating (in case of claudication).
  • Presence of rest pain.
  • ABPI measurements indicate severe compromise.

Treatment Methods

• Transluminal Angioplasty and Stenting:
  • Effective in expanding the iliac and femoropopliteal segments.
  • However, outcomes are less favorable below the knee.
• Surgeries:
  • Recommended for patients with severe symptoms when angioplasty is unsuccessful or not feasible.
  • For Aortoiliac occlusions: Aortofemoral bypass using a Dacron graft.
  • Iliac occlusion: Femorofemoral crossover graft:
    • Involves draining pus if present.
    • Antibiotic coverage in case of infections.

Amputations

Indications for Amputation

• Dead Limb:
  • Gangrene present.
• Deadly Limb:
  • Wet gangrene.
  • Spreading cellulitis.
  • Arteriovenous fistula.
  • Other conditions like malignancy.
• "Dead Loss" Limb:
  • Severe rest pain with irreparable critical leg ischemia.
  • Paralysis.
  • Other issues such as contracture or trauma.

Choice of Amputation

• Local Amputation of Digits: Suitable for gangrene affecting toes where surrounding tissues have relatively good blood supply.
• Transmetatarsal Amputation: Appropriate when several toes are involved, but proximal circulation remains adequate.

Amputations-Major

Amputations

Post-Operative Care of an Amputee

Complications

Peripheral arterial disorders-Repeats

Q1: Discuss the management of a 35 year old man with dry gangrene of big toe? (2004) 

Q2: How would you investigate a 30-year old lady admitted with dry gangrene of right index finger? (2011)

Q3: A 50-year-old male who is a chronic smoker presents with dry gangrene of Right great toe and rest pain in Right lower limb. On examination, it was found that his Right dorsalis pedis artery pulse is absent. (2016)
(i) Define chronic limb ischemia and discuss the causes of lower limb gangrene.
(ii) Discuss the management of the above mentioned condition.