Peripheral Arterial Disease

PAD Basics - Plaque Attack Primer

• Definition: Peripheral Arterial Disease (PAD) signifies atherosclerotic obstruction of arteries supplying the extremities, predominantly lower limbs. Leads to ↓ tissue perfusion.
• Pathophysiology: Progressive atherosclerotic plaque accumulation within arterial walls → luminal stenosis/occlusion → impaired blood flow → distal ischemia.
• Major Risk Factors:
  • Cigarette Smoking (paramount; dose-response relationship)
  • Diabetes Mellitus (accelerated atherogenesis, neuropathy)
  • Hypertension (endothelial injury)
  • Hyperlipidemia (↑LDL, ↓HDL cholesterol)
  • Advancing Age (>40 years, prevalence ↑ significantly >65)
  • Male Sex
  • Family History (premature CAD/PAD)
  • Chronic Kidney Disease

⭐ The superficial femoral artery (SFA) passing through the adductor (Hunter's) canal is the most common segment affected by significant stenosis in PAD.

Symptoms & Signs - Leg's Distress Signals

• Intermittent Claudication (IC):
  • Most common: exertional muscle pain (calf, thigh, buttock).
  • Relieved by rest (minutes); reproducible distance.
• Rest Pain:
  • Severe PAD: burning pain in forefoot/toes at rest, worse at night.
  • Relieved by dependency. Ominous sign.
• Critical Limb Ischemia (CLI):
  • Rest pain OR tissue loss (ulcers, gangrene).
  • Ankle Pressure < 50 mmHg; Toe Pressure < 30 mmHg.
• Physical Signs:
  • Skin: Pale, shiny, hairless, cool. Dependent rubor, pallor on elevation.
  • Pulses: ↓/absent distal pulses.
  • Capillary Refill: > 2 sec.
  • Ulcers: Painful, "punched-out" (toes, malleoli).
  • Gangrene.
  • Buerger's angle < 20°: severe ischemia.

⭐ Leriche Syndrome (Aortoiliac occlusive disease): Triad of buttock/thigh claudication, absent/diminished femoral pulses, and impotence in males.

Diagnosis & Staging - Sizing Up Ischemia

• Initial Non-Invasive Tests:
  • Ankle-Brachial Index (ABI): Key.
    • Normal: 1.0-1.4
    • Mild PAD: 0.71-0.90
    • Moderate PAD: 0.41-0.70
    • Severe PAD/CLI: ≤0.40
    • Non-compressible: >1.4 (use TBI)
  • Toe-Brachial Index (TBI): Use if ABI >1.4; TBI <0.7 diagnostic.
  • Duplex Ultrasound (DUS): Localizes stenosis; PSVR >2.0 for >50% stenosis.
  • Exercise ABI: Unmasks PAD if resting ABI normal; >20% drop positive.
• Advanced Imaging (Pre-intervention):
  • CTA, MRA, DSA (gold standard).
• Clinical Staging Systems:
  • Fontaine:
    • I: Asymptomatic
    • IIa: Mild claudication
    • IIb: Mod/Sev claudication
    • III: Rest pain
    • IV: Ulcer/gangrene
  • Rutherford: (Cat. 0-6) Detailed, objective.

⭐ ABI ≤0.90 diagnoses PAD. If ABI >1.4 (calcification), TBI <0.7 is more reliable (e.g., diabetes, ESRD).

Management Spectrum - Revascularization Roadmap

• Indications for Revascularization:
  • Lifestyle-limiting claudication (Rutherford 2-3)
  • Critical Limb Ischemia (CLI):
    • Rest pain (Rutherford 4)
    • Tissue loss (ulcer/gangrene) (Rutherford 5-6)
• Primary Goals: Symptom relief, limb salvage, improved Quality of Life (QoL).
• Modalities & Strategy (TASC II Guided):
  • Endovascular Therapy (EVT): Preferred for TASC A & B.
    • Percutaneous Transluminal Angioplasty (PTA) ± Stenting (BMS/DES)
    • Atherectomy (adjunctive)
  • Surgical Bypass: For TASC C & D, long occlusions, failed EVT.
    • Vein grafts (Great Saphenous Vein - GSV) > prosthetic.
    • Common: Aortobifemoral, Femoropopliteal, Femorodistal.
  • Hybrid Procedures: Combined EVT + open surgery.
• Post-Revascularization: Dual antiplatelet therapy (DAPT), statins, strict risk factor control.

⭐ CLI revascularization goal: Restore direct inline flow to ≥1 foot artery (angiosome concept) for optimal wound healing & limb salvage.

High‑Yield Points - ⚡ Biggest Takeaways

• Atherosclerosis is the most common cause of Peripheral Arterial Disease (PAD).
• Intermittent claudication (leg pain on exertion, relieved by rest) is the hallmark symptom.
• An Ankle-Brachial Index (ABI) < 0.9 is diagnostic for PAD.
• Critical Limb Ischemia (CLI) presents with rest pain, ischemic ulcers, or gangrene.
• Cilostazol is a key pharmacotherapy for symptomatic claudication.
• Smoking cessation is the single most important modifiable risk factor and intervention.
• Buerger's disease (thromboangiitis obliterans) is a non-atherosclerotic inflammatory disease strongly associated with young male smokers and a key differential diagnosis for PAD-like symptoms in this demographic.