Peripheral Vascular Disease
Larry W Kraiss MD
Associate Professor & Chief
Division of Vascular Surgery
larry.kraiss@hsc.utah.edu
Objectives
• Define the clinical role of a vascular surgeon
• Discuss the hemodynamics of peripheral
arterial disease (PAD) and the use of the
vascular laboratory in its assessment
• Discuss the clinical management of carotid
atherosclerosis
• Discuss the clinical management of lower
extremity PAD
The Circulatory System & the
Vascular Surgeon
• Arteries
– Occlusive disease
– Aneurysms
– Entrapment syndromes
• Veins
– Thrombosis
– Valvular insufficiency (reflux)
– Post-thrombotic syndrome
• Lymphatics (Lymphedema)
• Minimally invasive and traditional surgical treatment
Atherosclerosis:
the major cause of PVD
Risk factors:
–
–
–
–
–
Smoking
Diabetes
Hyperlipidemia
Family history
Homocystinemia
Pathophysiology:
– Luminal stenosis
– Plaque
rupture/erosion
• Embolization
• Thrombosis
Atherosclerotic Plaque Types
Stable
Unstable
Ruptured
Adapted from Atherosclerosis & Coronary Artery Disease, 1996
Stenoses produce changes in
pressure (DP) and flow
Vascular Surgery (Rutherford, Ed) 1977
Hemodynamics for Surgeons, 1975
DP is proportional to velocity
Hemodynamics for Surgeons, 1975
Collateral circulation develops
around significant stenoses
Vascular Surgery (Rutherford, Ed) 1977
Vascular Laboratory
Pressure testing (ABI’s)
Waveform analysis (PVR’s)
Doppler-based studies (duplex)
Continuous Wave (CW) Doppler
V = mean velocity
C = speed of sound in tissue
(1.56 x 105 cm/sec)
Df = mean frequency shift
fo = incident frequency
q = angle of incident sound
with reflector
Samples velocities from all reflectors
in the path of the sound beam.
Practical Noninvasive Vascular Diagnosis, 1982
Doppler waveform analysis
Normal
Moderate
Severe
Practical Noninvasive Vascular Diagnosis, 1982
Spectrum of extremity
arterial waveforms
Pressure testing: calculating the
ankle-brachial index (ABI)
• Doppler-recorded systolic
pressures
• Calculated for each lower
extremity
• Highest ankle SBP/highest
brachial SBP
• Normal value:
≥1.0
Practical Noninvasive Vascular Diagnosis, 1982
Plethysmography:
Pulse Volume Recording (PVR)
Practical Noninvasive Vascular Diagnosis,1982
Pulsed Wave Doppler
Allows sampling of velocities from a particular reflector
without interference from other reflectors in the path of
the sound beam.
Practical Noninvasive Vascular Diagnosis, 1982
Duplex Scanning:
combining real-time gray scale imaging
with pulsed doppler
SFA
SFV
Assignment of color hues
based on direction and
magnitude of frequency shift
Duplex Scanning in Vascular Disorders, 1993
Effect of stenosis on doppler waveforms
Surgical Management of Cerebrovascular Disease, 1995
With increasing stenosis, the peak systolic velocity (Df)
increases and spectral broadening (turbulence) appears
Questions?
Extracranial Carotid Atherosclerosis
• Atherosclerotic plaque at carotid bifurcation
and origin of the internal carotid artery
• Stroke: #3 cause of death in US
• Significant cause of stroke in patients:
– with plaque and symptoms >> 80%
• Pathophysiology: vulnerable plaque
– Thrombosis
– Embolization
Vascular Surgery (Rutherford, Ed), 2000
Symptoms of Carotid Atherosclerosis
• Stroke
• Transient Ischemic Attack (TIA):
– Stroke-like neurologic deficit
– Duration < 24 hours
• Directly related to anatomy of the ICA
– Ipsilateral ophthalmologic
(amaurosis fugax)
– Contralateral somatic
• Paralysis/paresis
• Sensory deficits
• Aphasia
– (if dominant hemisphere involved)
Vascular Surgery (Rutherford, Ed), 2000
Symptoms not (typically) due to
carotid atherosclerosis
• Posterior circulation
– Dizziness
– Ataxia
– Light-headedness
• Syncope (implies global cerebral
hypoperfusion)
• Binocular visual disturbances
Physical findings of carotid
atherosclerosis
•
•
•
•
Carotid bruit (unreliable)
Evidence of vascular disease in other areas
Neurologic deficit
Hollenhorst plaque (cholesterol emboli to
the retina)
Overall, history is most important in
determining subsequent clinical evaluation
(especially if TIA)
Carotid Atherosclerosis:
Diagnostic Imaging
• Duplex scanning
– Best screening tool
– Can be definitive diagnostic test
• Angiography
– Magnetic Resonance (MRA)
– Selective intra-arterial catheterization
– Useful to study lesions duplex cannot evaluate
• Calcification
• Unable to identify distal extent of lesion (not MRA)
• Discriminating more or less than 50% stenosis (not MRA)
Duplex Scanning of the Carotid Arteries
ECA
CCA
Duplex Scanning in Vascular Disorders, 1993
ICA
Surgical Management of Cerebrovascular Disease, 1995
Doppler waveforms from
diseased carotid arteries
Surgical Management of Cerebrovascular Disease, 1995
A)
0%
B)
1-15%
C)
16-49%
D)
50-79%
D+)
80-99%
Duplex-based classification
of carotid stenosis
Surgical Management of Cerebrovascular Disease, 1995
Carotid Angiography
Normal
Diseased
Surgical Management of Cerebrovascular Disease, 1995
Carotid MRA
Time of flight
(18 mins)
Gadolinium contrast
(10 seconds)
Vascular Surgery (Rutherford, Ed) 2000
Carotid Atherosclerosis:Treatment
• Medical
– Antiplatelet therapy (ASA, others)
– Statins
– Aggressive risk factor management
• Lesion-based intervention
– Surgical (carotid endarterectomy - CEA)
– Angioplasty/stenting
Choice of therapy depends on presence of
symptoms and the degree of stenosis
Carotid Endarterectomy
Wylie’s Atlas of Vascular Surgery, 1992
North American Symptomatic Carotid
Endarterectomy Trial (NASCET)
• Symptomatic patients (CVA, TIA, amaurosis
fugax)
• Carotid stenosis 30-70% and >70%
• Randomized, prospective trial of best medical
therapy (ASA) vs CEA (Level 1 evidence)
NASCET (1991) Results:
70-99% stenosis
CEA provides better stroke protection and survival compared to ASA
NASCET Collaborators, N Engl J Med, 1991
NASCET (1998) Results:
30 - 99% stenosis
•CEA better for lesions >50%
•No benefit for CEA if lesion <50%
Barnett, N Engl J Med, 1998
Asymptomatic Carotid
Atherosclerosis Study (ACAS)
• Natural history: increased risk of stroke as
stenosis worsens, especially > 80%
• Can CEA prevent CVA?
• ACAS trial randomized asymptomatic patients
with >60% stenosis to CEA or ASA
ACAS (1995) - Results
ASA: 11% risk of
stroke @ 5 yrs
CEA: 5% risk of
stroke @ 5 yrs
ACAS, JAMA, 1995
Current Recommendations for
Patients with Carotid Atherosclerosis
• Symptomatic
– >70% >> CEA
– 50-70% >> probable CEA
– <50% >> medical therapy (antiplatelet)
• Asymptomatic ?
– Depends on surgeon/center perioperative stroke
rate
– Patient preference
Carotid Atherosclerosis:
Future Directions
• What is the optimal role of angioplasty/stenting?
• Better antiplatelet agents?
– Clopidogrel (Plavix®)
– ASA/dipyridamole (Aggrenox®)
• Identification of the vulnerable plaque?
– MRA
– duplex
• Plaque regression?
– Statins
– Angiotensin II inhibition
Questions?
Peripheral Arterial Disease (PAD)
• Chronic
–
–
–
–
Slow, gradual luminal stenosis 2° plaque enlargement
Collateral development compensates
Symptoms proportional to disease burden
Exertional symptoms may appear first
• Acute
– Sudden occlusion in the absence of adequate collaterals
– Embolization (cardiogenic, proximal arteries)
– Thrombosis superimposed on occlusive disease
• plaque rupture
• failure of a previous vascular reconstruction
– Injury
Distribution of Chronic PAD
• Extremities
– Lower
– Upper?
• Mesenteric
– Celiac
– SMA
– IMA
• Renal (limited collateral potential)
Chronic PAD of the Lower
Extremities
• Aorto-iliac
• Femoropopliteal
(SFA most common)
• Tibial (especially
diabetics)
Vascular Surgery (Rutherford, Ed), 2000
Chronic LE PAD: Symptoms
• None
• Intermittent claudication
– Exertional muscular ischemia (calf, thigh, buttock)
– Analogous to stable angina
• Rest pain
– Blood supply inadequate to meet resting metabolic needs
– Affects tissue furthest from the heart
– May be relieved by dependency
• Tissue loss
– Non-healing traumatic ulcer
– Spontaneous gangrene
Chronic LE PAD: Physical Findings
• Pulse exam (especially femoral)
–
–
–
–
–
Distinguish normal vs abnormal
Symmetry
Bruit or thrill
Aneurysm
Evaluate non-palpable pulses with CW doppler
• Trophic signs (Muscular atrophy, absent hair growth)
• Dependent rubor/elevation pallor
• Tissue loss (ulceration, gangrene)
Chronic LE PAOD:
Non-invasive evaluation
• Ankle-Brachial Index (ABI)
–
–
–
–
Best brachial SBP/Ankle SBP
Normal value:
≥ 1.0
Claudication:
0.4 - 1.0
Limb-threatening:
≤ 0.4
• Calcified vessels produce inaccurately high ABI’s
– Common in diabetes and renal failure
– ABI should be consistent with other measures (PE,
PVR)
• Exercise (treadmill) testing
– reveals pressure drop in claudication when ABI normal
– can identify “pseudoclaudication” (i.e. spinal stenosis)
Ankle-Brachial Index (ABI)
ABI falls as disease
burden increases
Life expectancy falls
with ABI
Vascular Surgery (Rutherford, Ed) 2000
PAD is a risk factor for overall
cardiovascular mortality
Vascular Surgery (Rutherford, Ed), 2000
PAD patients are much more likely to die of MI than undergo amputation
Chronic LE PAD:
Treatment Considerations
• PAD is a marker of diffuse atherosclerosis
• PAD identifies a need for risk factor
intervention
• Claudication is a lifestyle-limiting (not typically
limb-threatening) problem
• Be aggressive if ischemia is limb-threatening
• Risk/benefit decision
Chronic LE PAD: Treatment Options
• Risk factor modification (almost always)
• Exercise (for claudication)
• Pharmacotherapy
– rarely for claudication
– not effective for limb-threatening ischemia
• Revascularization
– Endovascular (balloon angioplasty/stenting)
– Surgery
• Amputation
– failed revascularization
– may occasionally be appropriate 1° treatment
Intermittent Claudication
• Generally not limb-threatening
– Usually represents single-level disease (SFA most common)
– ABI ~ 0.7
– Risk factors for progression to limb-threatening ischemia
• Smoking
• Diabetes
• Low ABI at presentation (<0.50)
• First-line treatment
– Exercise
– Risk factor modification (especially smoking)
• Pharmacotherapy? (Good in theory, poor in practice)
• Revascularization? (Intolerable lifestyle limitation in
good risk patient)
Claudication & Smoking
• Risk factor for progression to limb-threatening
ischemia
• Shortens walking distance at any given ABI
• Cessation will predictably double walking
distance
Effect of exercise on claudication
• Predictably doubles walking
distance
• The sedentary, smoking
claudicant could quadruple
walking distance with
smoking cessation and
exercise
Gardner et al, J Cardiopulm Rehabil, 2002
Pharmacotherapy for claudication
Dawson et al, Am J Med, 2000
• Cilostazol (Pletal®) better than pentoxifylline (Trental®)
• ~ 50% improvement in walking distance with cilostazol
• Minimal benefit vs smoking cessation or exercise
Limb-threatening ischemia
• Rest pain or tissue loss
– Usually multi-level disease (Aorto-iliac, fem-pop, tibial)
– ABI typically <0.4
• Nearly absolute indication for revascularization
– some type of operation is in the patient’s future
– Frail elderly patients poor candidates for prosthetic
ambulation
– ?Primary amputation
• Non-ambulators
• Healthy with excellent potential for prosthetic function
Diabetes and PAD
• Risk factor for limb-threatening ischemia
– Higher likelihood of tibial artery disease
– Neuropathy predisposes to foot wounds
– Severe deep space foot infections
• Wound healing poorer at any given ABI vs nondiabetics
• Vascular calcification may artifactually elevate ABI
• Dismal prospects for limb-salvage if combined with
renal failure
Chronic LE PAOD:
Role of Angiography?
• NOT for diagnostic purposes
• Used for planning therapy after decision
to intervene has been made
Lower extremity revascularization:
endovascular options
• Balloon angioplasty/stenting
– Most commonly applied to aortoiliac segment
– Favorable lesion: short, concentric stenosis
– Unfavorable lesion: long, eccentric stenosis or
occlusion
• Atherectomy (rarely)
Lower extremity revascularization:
surgical options
Aorto-bifemoral bypass
Vascular Surgery (Rutherford, Ed) 2000
Lower extremity revascularization:
surgical options
Wylie’s Atlas of Vascular Surgery, 1992
Lower extremity revascularization:
Graft patency & limb salvage
Graft patency
(80-90% @ 5 yrs)
Limb salvage
(~90% @ 5 yrs)
Taylor, J Vasc Surg, 1990
Lower extremity revascularization:
Survival
Limb-threatening ischemia is a marker for a “malignant” disease
Taylor, J Vasc Surg, 1990
Summary
• Vascular surgeons diagnose and treat atherosclerosis in noncoronary vascular territories (carotid, lower extremities, renal,
mesenteric) using both endovascular and surgical techniques.
• Complete clinical evaluation possible in most patients with H&P
supplemented with vascular laboratory (common sense
hemodynamic approach)
• CEA can prevent strokes in patients with >50% stenosis (Level 1
evidence)
• Lower extremity PAD (ABI) is a marker for heavy systemic
atherosclerotic disease burden >> treat risk factors
• Primary treatment for claudication: exercise, stop smoking
• Limb-threatening ischemia >> revascularization
Basic PAD Facts
Which of the following statements regarding peripheral
arterial disease is NOT true?
A.
B.
C.
D.
PAD is a manifestation of atherosclerosis and has
become recognized as a “coronary disease
equivalent”
PAD has a distinct set of risk factors that separate it
from coronary artery disease.
Vulnerable plaques are characterized by large
necrotic cores and thin fibrous caps
Lesions causing symptoms of PAD typically occur
at major arterial bifurcations.
Dopplers
Which of the following statements about medical
dopplers is true?
A.
B.
C.
D.
The doppler will report greater frequency shifts as
blood flow velocity increases.
A duplex scan combines the technology of
continuous wave doppler and plethysmography.
A significant problem with pulsed dopplers is noise
contributed by movement in adjacent anatomic
structures.
Dopplers are unable to detect blood flow in arteries
that do not have a pulse.
Doppler Waveforms
Which statement is FALSE?
A.
B.
C.
D.
Extremity arteries distal to an occlusion may display
continuous forward flow on doppler examination.
The normal doppler waveform recorded from a healthy radial
artery at rest will show reversal of flow at end-systole.
Continuous forward flow throughout the cardiac cycle is
characteristic of a high-resistance artery at rest.
The normal internal carotid artery doppler waveform shows
continuous forward flow.
Carotid Disease (1)
A 64 year-old man with a history of smoking presents
after 2 episodes of transient left monocular
blindness. A left cervical bruit is present.
Which of the following actions during the first clinic visit
is NOT appropriate?
A.
B.
C.
D.
Administer 325 mg ASA.
Perform a complete neurological examination.
Obtain a carotid duplex scan.
Arrange for a stat carotid angiogram.
Carotid Disease (2)
The carotid duplex scan reveals peak systolic velocities >400
cm/sec in the left ICA consistent with a stenosis >70%. The
patient returns to clinic the following day, reporting no new
ocular symptoms.
The most appropriate action at this time is:
A.
B.
C.
D.
Obtain a carotid angiogram to verify the duplex results.
Maintain the patient on ASA and make plans to follow him
carefully since he hasn’t had any new symptoms since the
initial visit.
Refer the patient for carotid intervention in order to minimize
the risk of future stroke.
Obtain ophthalmologic consultation.
Carotid Disease (3)
Regarding the NASCET and ACAS randomized trials of carotid
stenosis treatment, which of the following statements is true?
A.
B.
C.
D.
Carotid endarterectomy provides equivalent benefits in terms
of absolute reduction of stroke risk in symptomatic and
asymptomatic patients.
Asymptomatic patients with carotid disease have a 50% risk
of stroke in one year with medical treatment.
Symptomatic patients with >70% stenosis derive the greatest
benefit from carotid endarterectomy.
Carotid angioplasty/stenting was shown to be superior to
medical therapy in preventing future stroke.
PAD (1)
Which of the following scenarios is most suggestive of
limb-threatening ischemia?
A.
B.
C.
D.
Forefoot pain when recumbent, monophasic pedal
doppler signals, ABI = 0.34.
Exertional calf pain, absent pedal pulses,
diminished hair growth below the knee.
Leg cramps at night, non-palpable popliteal pulse,
ABI = 0.68.
No symptoms, no palpable pulses at femoral or
pedal locations, ABI = 0.45.
PAD (2)
Regarding patients with intermittent claudication, which
of the following statements is true?
A.
B.
C.
D.
The risk of progression to limb loss exceeds the
risk of myocardial infarction.
Pharmacotherapy is the best means to increase
their walking distance.
Revascularization is performed to prevent limb
loss.
Risk factor modification and exercise is the best
means to increase their walking distance.
PAD (3)
A 48 year-old construction worker with a 60 pack-year smoking
history presents with 50’ right buttock claudication. He is in
imminent danger of being fired because he cannot walk
continuously around the job site. On physical exam, he has a
weakly palpable right femoral pulse (the left is normal) and an
ABI on the right of 0.65. After formulating a plan for smoking
cessation and risk factor modification, which of the following
additional measures is MOST appropriate in this situation?
A.
B.
C.
D.
Supervised walking program
Prescription for Pletal.
Referral for vocational counseling and job retraining.
Referral for angiography and possible revascularization.
PAD (4)
A 68 year-old woman with diabetes presents with dry gangrene of the left
5th toe, no pedal pulses but an ABI = 0.50. Five years ago, she
underwent right below-knee amputation for diabetic foot sepsis. She is
non-ambulatory but uses the left leg to transfer independently. She
has had two previous MI’s and underwent coronary stenting 6 months
ago. Despite treatment, she remains hypertensive with poor glycemic
control and an LDL cholesterol of 170.
Which of the following treatment plans is most appropriate?
A. Intensified risk factor modification and careful observation of the
gangrenous toe.
B. Left below-knee amputation since she is already non-ambulatory.
C. Revascularization of the left lower extremity.
D. Left 5th toe amputation alone since the ABI indicates that she does not
have limb-threatening ischemia.