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Peripheral Vascular Disease - 30-Mark Question Guide

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Definition and Overview

• PAD affects 8-12 million Americans and over 200 million people globally
• Prevalence increased 23.5% in the first decade of the 21st century
• Only 10% of PAD patients have classic intermittent claudication; the majority are asymptomatic or have atypical symptoms
• Only 19% of patients with PVD are symptomatic on clinical grounds

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Etiology and Risk Factors

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Classification

Fontaine Classification (most widely used clinically)

Rutherford Classification (more precise, used in research)

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Clinical Features

Chronic PAD (Intermittent Claudication)

• Fatigue, discomfort, cramping, or pain in the buttocks, hip, thigh, or calf induced by exercise and relieved by rest (within 5-10 minutes)
• The level of symptom localizes the disease: buttock/hip claudication = aortoiliac; thigh = common femoral; calf (most common) = superficial femoral or popliteal occlusion

Critical Limb-Threatening Ischemia (CLTI)

• Rest pain - persistent burning pain, worse at night, relieved by hanging the limb dependent
• Tissue loss - non-healing ulcers, gangrene (typically starts at toes/heel)

Acute Limb Ischemia (ALI) - "The 6 Ps"

1. Pain (sudden onset)
2. Pallor
3. Pulselessness
4. Paresthesias (sensory loss)
5. Paralysis (motor loss - sign of severe/irreversible ischemia)
6. Poikilothermia (perishing cold)

• Embolism: sudden onset, no prior vascular history, AF, cardiac source, contralateral normal pulses
• Thrombosis: gradual onset, prior claudication history, atherosclerotic risk factors, bilateral abnormal pulses

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Examination Findings

• Absent or diminished peripheral pulses (femoral, popliteal, dorsalis pedis, posterior tibial)
• Audible bruits over carotid, abdominal aorta, femoral vessels
• Dry skin, loss of hair, skin breakdown, muscle atrophy, cool limbs
• Pallor on elevation, dependent rubor (Buerger's test)
• Arteriovenous Doppler signal absent in severe ischemia

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Investigations

Ankle-Brachial Index (ABI) - First-Line Test

• Ratio of ankle systolic pressure (higher of dorsalis pedis/posterior tibial) to brachial pressure
• Normal: ≥1.0
• <0.9: diagnostic for PAD
• 0.5-0.9: claudication range
• <0.5: rest pain / CLTI
• ≥1.4: falsely elevated (calcified vessels - common in diabetes, CKD); use Toe-Brachial Index (TBI) instead
• TBI ≤0.7: hemodynamically significant arterial insufficiency
• Exercise ABI: A post-exercise drop in ABI to ≤0.9 confirms hemodynamically significant disease in patients with normal resting ABI

Duplex Ultrasound

• Sensitivity ~80%, specificity >95% for arterial occlusive disease
• Identifies site of lesion, flow disturbances, velocity changes
• First-line imaging; used for surveillance of bypass grafts

CT Angiography (CTA) and MR Angiography (MRA)

• Reserved for highly symptomatic patients prior to revascularization planning

Invasive Catheter Angiography (Gold Standard)

• Required for surgical/endovascular planning in complex cases

Segmental Pressures

• A pressure drop of >20 mmHg between two adjacent segments indicates significant disease at that level

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Management

A - General Principles

B - Risk Factor Modification

• Severity of PAD directly correlates with smoking history
• Cessation reduces mortality risk; most impactful single intervention

• Beta-blockers are NOT contraindicated (prior concern about worsening claudication was disproven in RCT by Radack et al., 1991)
• ACE inhibitors preferred: Ramipril reduced cardiac events by 25% in PAD patients

• High-intensity statins recommended for all patients with clinical ASCVD including PAD (target >50% LDL reduction) - per 2018 AHA/ACC guidelines
• Statins also increase walking distance (Mohler et al. 2003)

• Diabetes patients may develop CLTI without first developing claudication - vigilance required

• Aspirin 75-325 mg/day: reduces cardiovascular events and vascular-related deaths
• Clopidogrel: equally or more effective; preferred if aspirin intolerant
• Dual antiplatelet therapy: no added benefit over monotherapy; increases bleeding risk
• Warfarin: no evidence of benefit in PAD

C - Pharmacological Therapy for Claudication

D - Supervised Exercise Therapy

• First-line treatment for claudication
• Protocol: walking 3+ times per week, 30-60 minutes per session, for at least 12 weeks
• Walk until near-maximal claudication pain, then rest, then resume
• CLEVER trial (2012): Supervised exercise + optimal medical care provided greater improvement in peak walking time than stent revascularization at 6 months; stent group had better quality-of-life parameters

E - Revascularization

• Lifestyle-limiting claudication despite optimal medical/exercise therapy (20-30% of claudicants)
• CLTI (rest pain, tissue loss) - urgent indication
• ALI - emergent

• Percutaneous transluminal angioplasty (PTA) +/- stenting
• Preferred for aortoiliac disease (TASC A/B lesions), short-segment stenoses
• Catheter-directed intra-arterial thrombolysis for ALI (now preferred over systemic IV thrombolysis)

• Bypass grafting (aortobifemoral, femoro-popliteal, femoro-tibial)
• Endarterectomy
• Embolectomy with Fogarty catheter (for embolic ALI - simple thrombectomy often sufficient if no prior vascular disease)
• Amputation: reserved when limb is irreversibly ischemic or when revascularization fails

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Acute Limb Ischemia - Emergency Management

1. Immediate anticoagulation with IV heparin (prevents propagation)
2. ECG - diagnose atrial fibrillation (most common embolic source)
3. Echocardiogram - identify cardiac source (mural thrombus, valve disease, dilated cardiomyopathy)
4. CT scanning of descending thoracic and abdominal aorta - rule out aortic source
5. Definitive treatment:
   • Embolic: Surgical embolectomy (Fogarty catheter) or catheter-directed thrombolysis
   • Thrombotic: Angiography first for surgical planning, then bypass or endarterectomy
   • Irreversible ischemia: Primary amputation

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Differential Diagnosis of Claudication

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Prognosis

• With optimal medical treatment, <5% of claudicants progress to CLTI requiring amputation
• However, systemic cardiovascular prognosis is poor: high rates of MI, stroke, cardiovascular death
• 10-year mortality in PAD patients is significantly elevated (Criqui et al. 1992)
• 20-30% of claudicants eventually require intervention
• Annual ABI monitoring recommended for all PAD patients

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Key Facts for 30-Mark Exam

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