Transcript Basic Science Peripheral Vascular Disease

Basic Science
Peripheral Vascular Disease
Peripheral Arterial Occlusive
Disease
Basic Considerations
Atherosclerosis - Risk factors
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Hypercholesterolemia
Diabetes
Hypertension
Smoking
Relative factors - advanced age, male
gender, hypertriglyceridemia,
hyperhomocysteinemia, sedentary lifestyle,
family history
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
Critical Diameter
Adaptive arterial enlargement preserves
luminal caliber until a critical plaque mass
is reached
Diagnostic Modalities
• Non-invasive
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ABIs
Segmental limb pressures
Limb plethysmography
Exercise testing
Doppler & duplex ultrasound
MR angiography
• Invasive
– Contrast arteriography
– CT angiography
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 < 0.4
• May be falsely elevated in
calcified vessels (DM)
ABI algorithm
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
Medical Therapy
• Risk factor management
– Lipid-lowering therapy
– Smoking cessation
• Exercise regimen
• Antiplatelet therapy - ASA, ticlodipine,
clopidogrel
• Vasoactive - Cilostazol (Pletal),
pentoxyfilline (Trental)
Surgical Interventions
Bypass
Endarterectomy
PTA/Stenting
Stenosis vs.
Either
Occlusion
Length of segment Not a factor
Stenosis > occlusion
Preferably short
Stenosis >
occlusion
Preferably short
Vessel caliber
> 2 mm
Preferably > 5-6 mm
Preferably > 4 mm
Most suitable
anatomic sites
Aortic arch through Carotid bifurcation
distal femoral
Distal abdominal
aorta and iliacs
Peripheral Arterial Occlusive
Disease
Carotid Stenosis
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
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
Stroke
• Third leading cause of death
• Major modifiable risk factors
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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
Carotid
Stenosis
• 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
Presentation
• Asymptomatic bruit
• Amaurosis fugax – transient monocular
visual disturbance
• Lateralizing TIA
• Crescendo TIA
• Stroke-in-evolution
• CVA
Diagnostic
Algorithm
Duplex Scanning
• B-mode scan – Anatomic information
• Doppler – Flow velocities
– Plague  Increased peak and range of velocities
Indications for CEA
• Symptomatic – TIA, AF, small stroke
– Proven – Stenosis > 70%
– Acceptable – Stenosis 50-69%
– Lesser symptoms, failed medical therapy
• Asymptomatic
– Proven – Stenosis > 60%, good risk
– Uncertain
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High risk patient
Surgeon morbidity-mortality >3%
Combined carotid coronary operation
Non-stenotic ulcerative lesions
• Presence of ulceration or contralateral occlusion
may lower threshhold for surgery
Peripheral Arterial Occlusive
Disease
Chronic Occlusive Disease of the
Lower Extremities
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
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
Prevalence and survival
• 2-3% population >50y, 10% > 70y
• Lower extremity ischemia associated with
decreased 5-yr survival
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97.4 % intermittent claudication
80% claudication requiring surgery
48% limb-threatening ischemia
12% re-op for limb-threatening ischemia
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
Location of pain
Location of lesion
Hip/Buttocks
Aortoiliac
Thigh
Common femoral
Upper 2/3 calf
SFA
Lower 1/3 calf
Popliteal
Diagnostic algorithm
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
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
Graft
• Autologous Vein Graft - SV, arm vein
• Synthetic - PTFE, Decron
• Graft failure
– 30 days - Technical error
– 30 days to 2 years - Intimal hyperplasia
– >2 years - Progression of atheresclerosis
• Surveillance
– Duplex 6 wks peri-op, 3 months/2 yrs, q 6 month
Peripheral Arterial Occlusive
Disease
Acute Thromboembolic Disease
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
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
Epidemiology
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Incidence: 1.7 cases / 10,000 people / Yr.
Elderly
Male > female
Mortality 15%, Amputation 10-30%
Medical co-morbidities common
– CVD 12%, CAD 45%, DM, 31%, HTN 60%, CHF
13%
Sites of Embolization
• Bifurcations
– Femoral - 40%
– Aortic - 10-15%
– Iliac - 15%
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Popliteal - 10%
Upper extremities - 10%
Cerebral - 10-15%
Mesenteric/visceral - 5%
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
6 Ps
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Pain
Pallor
Pulselessness
Paresthesia
Paraparesis
Poikilothermia
Palpable Pulses
Location of Obstruction
Femoral
Popliteal
Pedal
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Aortoiliac segment
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Femoral segment
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Distal popliteal ± tibials
(Popliteal anerysm)
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Distal popliteal ± tibials
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
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
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
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
Prevention and management
• Hydration
– UO 100cc/hr
• Alkalinization of urine
– Prevent myoglobin precipitation in renal
tubules
• Mannitol
– Antioxidant, osmotic diuretic
• Insulin/glucose
• Fasciotomy
Question
Regarding compartment syndrome, which of the
following is correct?
A. The leg is divided into two compartments--anterior
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
Question
Regarding compartment syndrome, which of the
following is correct?
A. The leg is divided into two compartments--anterior
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
Anatomic Compartments of leg
4 compartments:
Anterior
Lateral (Peroneal)
Deep Posterior
Superficial Posterior
Pathophysiology
CELL INJURY
CELL SWELLING
TRANSUDATION OF
FLUID
 INTRACOMPARTMENT
PRESSURE
 VENULAR
PRESSURE
NO NUTRIENT FLOW
 CAPILLARY
TRANSUDATE
TISSUE PRES. = CAP.
HYDR. PRES.
ISCHEMIA
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
Indications for fasciotomy
• Classically > 40-45 mm Hg at any point
or > 30 mm Hg for 3-4 hrs
• Arterial perfusion pressure is paramount
– Mean arterial pressure - interstitial pressure < 30
mm Hg is critical
– Diastolic pressure - compartment pressure < 20
mm Hg is critical
Fasciotomy
Thoracic Outlet Syndrome
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
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
Anatomy
• Interscalene triangle artery and nerves
• Costoclavicular space vein
• Subcoracoid area artery, vein, nerves
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
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
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
Buerger’s Disease
Question
Which of the following characteristics of Buerger’s
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
Question
Which of the following characteristics of Buerger’s
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
Buerger’s 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
Buerger’s 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
Buerger’s Disease - Management
• Revascularization options are limited
• Clinical remission with smoking cessation
• Sympathectomy has a limited role in
patients with ulcerations