Basic Science Peripheral Vascular Disease

1
Basic Science Peripheral
Vascular Disease
2
Peripheral Arterial Occlusive Disease

• Basic Considerations

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Atherosclerosis - Risk factors

• Hypercholesterolemia
• Diabetes
• Hypertension
• Smoking
• Relative factors - advanced age, male gender,
  hypertriglyceridemia, hyperhomocysteinemia,
  sedentary lifestyle, family history

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Pathophysiology of Atherosclerosis

• Atheroma porridge Sclerosis hardening
• Response to endothelial injury hypothesis
• Loss of barrier function, antiadhesive properties
  and antiproliferative influence on underlying
  SMCs
• Migration and proliferation of SMCs ? production
  of ECM
• Oxidized lipid accumulation in vessel walls
• Recruitment of macrophages and lymphocytes
• Adherence of platelets to dysfunctional
  endothelium, exposed matrix, and macrophages

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Critical Diameter

• Adaptive arterial enlargement preserves
  luminal caliber until a critical plaque mass is
  reached

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Diagnostic Modalities

• Non-invasive
• ABIs
• Segmental limb pressures
• Limb plethysmography
• Exercise testing
• Doppler duplex ultrasound
• MR angiography
• Invasive
• Contrast arteriography
• CT angiography

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Ankle-Brachial Index

• Comparison of ankle pressure to brachial SBP
• Reproducible, useful for long term surveillance
• Normal 0.85-1.2
• Claudicants 0.5-0.7
• Critical ischemia lt 0.4
• May be falsely elevated in calcified vessels (DM)

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ABI algorithm
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PVR

• Calibrated air plethysmographic wave form
  recording system
• Helps localize site of obstruction
• Placement of cuffs at levels of proximal and
  distal thigh, calf and ankle

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Medical Therapy

• Risk factor management
• Lipid-lowering therapy
• Smoking cessation
• Exercise regimen
• Antiplatelet therapy - ASA, ticlodipine,
  clopidogrel
• Vasoactive - Cilostazol (Pletal), pentoxyfilline
  (Trental)

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Surgical Interventions
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Peripheral Arterial Occlusive Disease

• Carotid Stenosis

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Question

• A patient with symptomatic 85 carotid stenosis
  is
• found to have asymptomatic 50 stenosis on the
• contralateral side. Appropriate initial
  treatment includes
• A. Simultaneous bilateral CEA
• B. Staged bilateral CEA with 1 week interval
  between stages
• C. CEA on symptomatic side only
• D. CEA on side of greatest stenosis regardless of
  symptoms

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Question

• A patient with symptomatic 85 carotid stenosis
  is
• found to have asymptomatic 50 stenosis on the
• contralateral side. Appropriate initial
  treatment includes
• A. Simultaneous bilateral CEA
• B. Staged bilateral CEA with 1 week interval
  between stages
• C. CEA on symptomatic side only
• D. CEA on side of greatest stenosis regardless of
  symptoms

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Stroke

• Third leading cause of death
• Major modifiable risk factors
• HTN
• Smoking
• Carotid stenosis
• Cardiac diseases - a-fib, endocarditis, MS,
  recent MI
• Atherosclerosis leading cause of ischemic
  stroke
• Artery-to-artery emboli
• Thrombotic occlusion
• Hypoperfusion from advanced stenosis

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CarotidStenosis

• Causes of atherosclerosis at bifurcation
• Low wall shear stress
• Flow separation
• Complex flow reversal along posterior wall of
  sinus
• Sequence of events
• b. Establishment of plaque
• c. Soft, central necrotic core with overlying
  fibrous cap
• d. Disruption of cap - necrotic cellular debris
  and lipid material become atherogenic emboli
• e. Empty necrotic core becomes a deep ulcer
  thrombogenic ? thromboembolism

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Presentation

• Asymptomatic bruit
• Amaurosis fugax transient monocular visual
  disturbance
• Lateralizing TIA
• Crescendo TIA
• Stroke-in-evolution
• CVA

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Diagnostic Algorithm
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Duplex Scanning

• B-mode scan Anatomic information
• Doppler Flow velocities
• Plague ? Increased peak and range of velocities

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Indications for CEA

• Symptomatic TIA, AF, small stroke
• Proven Stenosis gt 70
• Acceptable Stenosis 50-69
• Lesser symptoms, failed medical therapy
• Asymptomatic
• Proven Stenosis gt 60, good risk
• Uncertain
• High risk patient
• Surgeon morbidity-mortality gt3
• Combined carotid coronary operation
• Non-stenotic ulcerative lesions
• Presence of ulceration or contralateral occlusion
  may lower threshhold for surgery

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Peripheral Arterial Occlusive Disease

• Chronic Occlusive Disease of the Lower Extremities

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Question

• Which of the following is an indication for
  bypass?
• A. Claudication within ½ block
• B. ABI of 0.5
• C. Rest pain
• D. Occlusion of the superficial femoral and
  anterior tibial arteries

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Question

• Which of the following is an indication for
  bypass?
• A. Claudication within ½ block
• B. ABI of 0.5
• C. Rest pain
• D. Occlusion of the superficial femoral and
  anterior tibial arteries

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Prevalence and survival

• 2-3 population gt50y, 10 gt 70y
• Lower extremity ischemia associated with
  decreased 5-yr survival
• 97.4 intermittent claudication
• 80 claudication requiring surgery
• 48 limb-threatening ischemia
• 12 re-op for limb-threatening ischemia

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Signs and symptoms

• Claudication
• Extremity pain, discomfort or weakness
• Consistently produced by the same amount of
  activity
• Relieved with rest
• Rest pain
• Localized to metatarsal heads and toes
• Worse with elevation or recumbent position
• Improved with foot dependency

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• Temperature
• Hair loss
• Pallor
• Nail hypertrophy
• Ulcer
• Gangrene
• Dry - non infected black eschar
• Wet - tissue maceration and purulence

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Diagnostic algorithm
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Question

• Late vein graft failure is due to
• A. Atherosclerotic changes in the vein
• B. Vein thrombosis
• C. Fibrointimal hyperplasia
• D. Kinking of the vein graft

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Question

• Late vein graft failure is due to
• A. Atherosclerotic changes in the vein
• B. Vein thrombosis
• C. Fibrointimal hyperplasia
• D. Kinking of the vein graft

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Graft

• Autologous Vein Graft - SV, arm vein
• Synthetic - PTFE, Decron
• Graft failure
• 30 days - Technical error
• 30 days to 2 years - Intimal hyperplasia
• gt2 years - Progression of atheresclerosis
• Surveillance
• Duplex 6 wks peri-op, 3 months/2 yrs, q 6 month

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Peripheral Arterial Occlusive Disease

• Acute Thromboembolic Disease

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Question

• 86 yo F with PMHx CAD, HTN, DM, A fib
• presents w/ sudden onset left lower extremity
  pain.
• Palpable femoral pulses. No palpable or doppler
• signals on left. Nl on right. Where is her
  obstruction?
• A. Common femoral artery
• B. Popliteal artery
• C. Iliac bifurcation
• D. Superficial femoral artery

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Question

• 86 yo F with PMHx CAD, HTN, DM, A fib
• presents w/ sudden onset left lower extremity
  pain.
• Palpable femoral pulses. No palpable or doppler
• signals on left. Nl on right. Where is her
  obstruction?
• A. Common femoral artery
• B. Popliteal artery
• C. Iliac bifurcation
• D. Superficial femoral artery

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Epidemiology

• Incidence 1.7 cases / 10,000 people / Yr.
• Elderly
• Male gt female
• Mortality 15, Amputation 10-30
• Medical co-morbidities common
• CVD 12, CAD 45, DM, 31, HTN 60, CHF 13

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Sites of Embolization

• Bifurcations
• Femoral - 40
• Aortic - 10-15
• Iliac - 15
• Popliteal - 10
• Upper extremities - 10
• Cerebral - 10-15
• Mesenteric/visceral - 5

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History

• The onset and duration of symptoms
• Pain
• Sudden onset - embolic
• Long-standing before acute event - thrombotic
• Previous revascularization
• Risk factors for atherosclerotic heart disease

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6 Ps

• Pain
• Pallor
• Pulselessness
• Paresthesia
• Paraparesis
• Poikilothermia

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Management

• Arteriography
• Operative planning target vessel
• Therapeutic thrombolysis, angioplasty
• Should not delay revascularization may be
  obtained intra-operatively
• Rapid systemic anticoagulation
• Heparin bolus/drip
• Prevent propagation of thrombus, distal
  thrombosis, venous thrombosis
• Surgery- Embolectomy
• Percutaneous Thrombectomy

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Question

• 6 hours after a femoral-tibial artery bypass for
• advanced acute ischemia, the lower leg is
• swollen and painful with palpable pulse. The
• likely etiology is
• A. DVT
• B. Reperfusion injury
• C. Thrombosis
• D. Arterial spasm

42
Question

• 6 hours after a femoral-tibial artery bypass for
• advanced acute ischemia, the lower leg is
• swollen and painful with palpable pulse. The
• likely etiology is
• A. DVT
• B. Reperfusion injury
• C. Thrombosis
• D. Arterial spasm

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Reperfusion injury

• Local effects
• Oxygen radicals accumulate
• Compound cellular insult
• Systemic effects
• Acid, potassium, cytokines, cardiodepressants
  accumulate in ischemic limb
• Sudden cardiac arrhythmias
• Renal failure
• Acute lung injury

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Prevention and management

• Hydration
• UO 100cc/hr
• Alkalinization of urine
• Prevent myoglobin precipitation in renal tubules
• Mannitol
• Antioxidant, osmotic diuretic
• Insulin/glucose
• Fasciotomy

45
Question

• Regarding compartment syndrome, which of the
• following is correct?
• A. The leg is divided into two compartments--anter
  ior and posterior
• B. The most commonly affected compartment is the
  posterior
• C. The earliest manifestation of acute
  compartment syndrome is pain
• D. Patients with compartment pressures greater
  than 15 mm Hg should undergo fasciotomy

46
Question

• Regarding compartment syndrome, which of the
• following is correct?
• A. The leg is divided into two compartments--anter
  ior and posterior
• B. The most commonly affected compartment is the
  posterior
• C. The earliest manifestation of acute
  compartment syndrome is pain
• D. Patients with compartment pressures greater
  than 15 mm Hg should undergo fasciotomy

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Anatomic Compartments of leg

• 4 compartments
• Anterior
• Lateral (Peroneal)
• Deep Posterior
• Superficial Posterior

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Pathophysiology
CELL INJURY
CELL SWELLING
TRANSUDATION OF FLUID
? INTRACOMPARTMENT PRESSURE
? CAPILLARY TRANSUDATE
TISSUE PRES. CAP. HYDR. PRES.
? VENULAR PRESSURE
ISCHEMIA
NO NUTRIENT FLOW
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Signs and symptoms

• Pallor and pulselessness
• Not always reliable
• Distal pulses may be present
• Paralysis - Late symptom
• Pain - Severe and out of proportion, increased on
  passive motion
• Paresthesia - Numbness, weak dorsiflexion,
  numbness in 1st dorsal web space
• Tender, swollen, tense muscle compartments

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Indications for fasciotomy

• Classically gt 40-45 mm Hg at any point
• or gt 30 mm Hg for 3-4 hrs
• Arterial perfusion pressure is paramount
• Mean arterial pressure - interstitial pressure lt
  30 mm Hg is critical
• Diastolic pressure - compartment pressure lt 20
  mm Hg is critical

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Fasciotomy
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Thoracic Outlet Syndrome
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Question

• The most common finding associated with
• thoracic outlet syndrome is
• A. Signs of brachial plexus nerve injury
• B. Subclavian vein thrombosis
• C. Subclavian artery aneurysm
• D. Presence of cervical rib on chest XR

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Question

• The most common finding associated with
• thoracic outlet syndrome is
• A. Signs of brachial plexus nerve injury
• B. Subclavian vein thrombosis
• C. Subclavian artery aneurysm
• D. Presence of cervical rib on chest XR

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Anatomy

• Interscalene triangle - artery and nerves
• Costoclavicular space - vein
• Subcoracoid area - artery, vein, nerves

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Thoracic Outlet Syndrome

• Upper extremity symptoms due to compression of
  the neurovascular bundle in the thoracic outlet
  area
• 3 Types
• Neurogenic - most common (95)
• Venous 2-3
• Arterial 1
• Exacerbated by elevation, abduction,
  hyperextension of arm

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Etiology

• Bone - cervical rib, long transverse process of
  C7, abnormal first rib, osteoarthritis
• Muscles - scalene anomalies
• Trauma - neck hematoma, bone dislocation
• Fibrous bands - congenital and acquired
• Neoplasm
• Narrowing of the costoclavicular space
• Subclavius muscle, costoclavicular ligament,
  hypertrophic callus

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Management

• Conservative
• Improvements in postural sitting, standing, and
  sleeping position
• Behavior modification at work
• Muscle stretching and strengthening exercises
• Successfully treats 50-90 of patients
• Surgery - Transaxillary first rib resection

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Buergers Disease
60
Question

• Which of the following characteristics of
  Buergers
• disease is true?
• A. Most commonly observed in young non-smoking
  females
• B. It affects mainly the large arteries of the
  upper ext
• C. Is characterized by sharply segmental acute
  and chronic vasculitis of medium-sized and small
  arteries
• D. Vascular reconstructive surgery is the main
  therapy
• E. Arterial involvement progresses in a proximal
  to distal fashion

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Question

• Which of the following characteristics of
  Buergers
• disease is true?
• A. Most commonly observed in young non-smoking
  females
• B. It affects mainly the large arteries of the
  upper ext
• C. Is characterized by sharply segmental acute
  and chronic vasculitis of medium-sized and small
  arteries
• D. Vascular reconstructive surgery is the main
  therapy
• E. Arterial involvement progresses in a proximal
  to distal fashion

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Buergers Disease Thrombangiitis Obliterans

• Exclusively associated with cigarette smoking
• More prevalent in Middle East and Asia
• Occlusive lesions seen in muscular arteries, with
  a predilection for tibial vessels
• Presentation - rest pain, gangrene and ulceration

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Buergers Disease

• Recurrent superficial thrombophlebitis
  (phlebitis migrans)
• Young adults, heavy smokers, no other
  atherosclerotic risk factors
• Angiography - diffuse occlusion of distal
  extremity vessels
• Progression - distal to proximal

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Buergers Disease - Management

• Revascularization options are limited
• Clinical remission with smoking cessation
• Sympathectomy has a limited role in patients with
  ulcerations