Vascular: Peripheral Arterial Disease (PAD)

Peripheral Arterial Disease (PAD)

Basics

  • Definition: Narrowed Arteries Causing Decreased Blood Flow to Extremities
  • Most Common Cause: Atherosclerosis

Risk Factors

  • Tobacco – Strongest Risk Factor
  • Diabetes – Second Strongest Risk Factor
  • Elderly
    • Proximal Aortoiliac Disease Associated with Younger Age
  • Hypertension
  • Hyperlipidemia
  • Renal Disease
  • Hyperhomocysteinemia
  • Male Sex

Prognosis

  • Strong Predictor of Future Cardiovascular Disease (MI or CVA)
  • 5-Year Mortality:
    • Asymptomatic: 19%
    • Symptomatic: 24-30%
  • Risk of Future Major Amputation with Claudication: 1% per Year
    • 5-Years: < 5%
    • 10-Years: 12%
  • 7% (4-11%) of Asymptomatic Patient Will Develop Intermittent Claudication After 5-Years

Site of Stenosis

  • Generally Divided into 3 Levels:
    • Aortoiliac Disease
    • Femoropopliteal Disease
    • Tibioperoneal Disease
  • Most Common Sites:
    • Overall in Legs: Hunter’s Canal
    • In Smokers: Superficial Femoral Artery
    • In DM/CKD: Infrapopliteal Disease
  • Least Likely Site: Peroneal Artery – Due to Deep Compartment Location

Medial Calcinosis (Monckeberg Arteriosclerosis)

  • Cause: Calcification of Tunica Media
    • Seen in DM & ESRD
  • Most Common Site: Tibial Vessels
  • Vessels are Rigid & Difficult to Compress (Falsely Elevated ABI)
  • Spares Digital Vessels (Toe Pressure & Transcutaneous Oximetry More Reliable)

Presentation

  • Most Commonly Asymptomatic & Found Incidentally
  • Intermittent Claudication (Activity-Induced Pain)
    • Site of Occlusion – Level of Symptoms
      • Aortoiliac – Buttock, Hip & Thigh
      • External Iliac – Thigh
      • Femoral – Calf
      • Popliteal – Foot
      • Infrapopliteal – Often Have No Pain
    • Calf Pain is the Most Common Site
  • Ischemic Resting Pain
  • Ulceration & Gangrene
  • Critical Limb Ischemia
  • Muscle Atrophy
  • Leriche Syndrome
    • Triad: Diminished Femoral Pulse, Buttock Claudication & Impotence
    • Indicates Aortoiliac Occlusive Disease

Symptomatic Grouping

  • Intermittent Claudication (IC) – Activity-Induced Pain but Not at Rest
  • Chronic Limb-Threatening Ischemia (CLTI) – Rest Pain or Tissue Necrosis
    • *Previously Called Critical Limb Ischemia (CLI)
  • Acute Limb Ischemia (ALI) – *See Vascular: Acute Limb Ischemia

Diagnosis

  • Ankle-Brachial Index (ABI)
    • Best Initial Screening Test
    • ABI = Ankle / Brachial Blood Pressure
      • Ankle: Highest DP or PT on That Side
      • Brachial: Highest on Either Side Used for Both Legs
    • Values:
      • 0.9-1.2 – Normal (When Supine Arm May Be 20% Higher Than Ankle)
      • < 0.9 – Diagnostic of PAD
      • < 0.7 – Often See Claudication
      • < 0.4 – Often See Rest Pain
      • < 0.3-0.4 – Often See Ulcers & Gangrene
    • Not Reliable in DM or ESRD – Calcified Vessels Give False Elevation
    • If Initial ABI is Normal Despite Claudication Symptoms – Consider Repeat ABI After Exercise
  • Doppler US
    • Useful Bedside Exam in Evaluation but Need More for Diagnosis
    • Waveforms:
      • Normal: Triphasic
        • Systole – Rapid Antegrade Flow
        • Early Diastole – Transient Retrograde Flow
        • Late Diastole – Slow Antegrade Flow
      • Abnormal: Biphasic, Monophasic or None
        • Waveform Flattens & Early Diastolic Retrograde Flow is Lost
  • Arterial Duplex US
    • Good for Initial Work-Up
    • “Duplex” – Pulsed Doppler System (Velocity) & Real-Time B Mode US (Image)
  • CTA
    • Typically the Diagnostic Modality of Choice
  • Angiography
    • Gold Standard but More Invasive

MRA Demonstrating CFA Stenosis 1

Normal Distal Angiogram 2

Doppler Waveforms

Peripheral Arterial Disease (PAD) – Classification

Fontaine Stages

  • Stage I: Asymptomatic
  • Stage II: Claudication
    • IIa: Mild (At Distance > 200 m)
    • IIb: Moderate-Severe (At Distance < 200 m)
  • Stage III: Ischemic Rest Pain
  • Stage IV: Ulceration or Gangrene

Rutherford Grades/Categories for Chronic Limb Ischemia

Grade Category Clinical Description Objective Criteria
0 0 Asymptomatic Normal Treadmill or Reactive Hyperemia Test
I 1 Mild Claudication Completes Treadmill Exercise
AP > 50 mmHg After Exercise but ≥ 20 mmHg Under Resting Value
I 2 Moderate Claudication Between Categories 1 and 3
I 3 Severe Claudication Cannot Complete Treadmill Exercise
AP < 50 mmHg After Exercise
II 4 Ischemic Rest Pain Resting AP < 30-50 mmHg
TP < 30 mmHg
Ankle/Metatarsal PVR Flat or Barely Pulsatile
III 5 Minor Tissue Loss Resting AP < 50-70 mmHg
TP < 40 mmHg in Nondiabetics
TP < 50 mmHg in Diabetics
Ankle/Metatarsal PVR Flat or Barely Pulsatile
tcPO2 < 30 mmHg
III 6 Major Tissue Loss Same as Category 5
    • *AP – Ankle Pressure, TP – Toe Pressure, PVR – Pulse Volume Recording, tcPO2 – Transcutaneous Oxygen

Other Systems

  • Bollinger Classification – Based on Angiographic Description
  • Graziani Classification – Anatomic Classification in Diabetic Foot Ulcers
  • Trans-Atlantic Inter-Society Consensus (TASC II) – Describes Anatomic Classification of Disease

Peripheral Arterial Disease (PAD) – Treatment

Management Approach

  • Intermittent Claudication
    • Initial Tx: Medical Management
    • If Fails & Lifestyle-Limiting: Endovascular Revascularization
      • May Consider Surgical Revascularization in Select Cases
  • Chronic Limb-Threatening Ischemia
    • Preferred Tx: Revascularization (Endovascular or Surgical)
    • Amputation Indications:
      • Overwhelming Infection
      • Vascular Disease Unable to be Reconstructed
    • Consider Medical Management Alone if:
      • Superficial Ulceration with Vascular Disease Unable to be Reconstructed to Avoid Amputation
      • Avoid Major Amputation in High-Risk Patients Near End-of-Life
  • Acute Limb Ischemia

Medical Management

  • Smoking Cessation #1
  • Exercise Therapy
    • Most Effective Exercise: Treadmill or Track Walking
      • Resistance Training Beneficial but Should Not Substitute
    • Exercise Beyond Initial Onset of Pain, Until Pain is Moderate-Severe – Increases Collaterals
  • Antiplatelet Therapy (Aspirin/Clopidogrel)
  • Statin
  • Medications for Intermittent Claudication Symptomatic Relief:
    • Cilostazol (Pletal)
      • PDE3 Inhibitor/Vasodilator Provides Symptomatic Relief
      • Contraindicated if History of Congestive Heart Failure
    • Pentoxifylline
      • Methylxanthine Derivative Improves Oxygen Delivery by Enhancing RBC Deformability
      • Can Interfere with Blood Clotting/Coumadin

Aortoiliac Disease Revascularization

  • Endovascular Angioplasty & Stenting
    • Used with Increasing Frequency
    • Previously Limited to Short-Segment TASC A/B Lesions but Now Being Used for Even Longer-Segment Lesions
    • Relative Contraindications:
      • Extensive Aortic/Renal Involvement
      • Heavy Calcification – Risk Rupture
      • Poor Renal Function (Unless Already on Dialysis – Will Clear Contrast)
  • Aortofemoral/Aortobifemoral Bypass
    • Gold Standard Surgical Procedure
  • Axillofemoral/Axillobifemoral Bypass
    • Possible Indications:
      • “Hostile” Abdomen
      • Stoma Presence
      • Infected Grafts
      • Prior Radiation
  • Iliofemoral Bypass
  • Femorofemoral (Fem-Fem) Bypass
  • Aortoiliac Endarterectomy

Infrainguinal (Femoropopliteal/Tibioperoneal) Disease Revascularization

  • Endovascular Angioplasty & Stenting
    • Preferred Approach
    • Relative Contraindications:
      • Long Segment Stenosis/Occlusion
      • Multifocal Stenosis
      • Eccentric Calcified Stenosis
  • Surgical Bypass
  • Common Femoral Endarterectomy
    • Poor Access at Other Sites

Endovascular Stent Placement; (A) Stent Mounted on Catheter, (B) Balloon Inflated and Stent Expanded, (C) Balloon Deflated, (D) Catheter Removed 3

Axillobifemoral Bypass 4

Femorofemoral Bypass 5

Femoral Endarterectomy 6

Upper Extremity Stenosis

Basics

  • Much Less Common than Lower Extremity Disease
  • Upper Extremity Disease is More Likely Caused by Autoimmune or Connective Tissue Disease
    • Atherosclerosis is Not as Significant as Lower Extremity Disease
  • Most Common Site: Subclavian

Presentation

  • Proximal Disease is Usually Asymptomatic from Collaterals
  • Intermittent Pain with Use
  • Ischemic Resting Pain, Particularly in the Digits
  • Ulceration & Gangrene
  • Critical Limb Ischemia
  • Muscle Atrophy

Associated Syndromes

  • Subclavian Steal Syndrome
    • Reverse Flow Through Vertebral Artery from Proximal Subclavian Stenosis
    • Causes Limb & Vertebrobasilar Symptoms
  • Coronary-Subclavian Steal Syndrome
    • After CABG with LIMA
    • Retrograde Flow Through LIMA to Subclavian

Upper Extremity Disease Revascularization

  • Endovascular Angioplasty & Stenting
    • Utilized Less Frequently than in Lower Extremity Disease
  • Surgical Bypass

Subclavian Steal Syndrome 7

References

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