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Lower limb ischaemia
Peripheral vascular disease commonly affects the
arteries supplying the leg and is mostly caused by
atherosclerosis. Restriction of blood flow, due to
arterial stenosis or occlusion, often leads patients
to complain of muscle pain on walking
(intermittent claudication).
Any further reduction in blood flow causes
ischaemic pain at rest, which affects the foot.
Ulceration and gangrene may then supervene
and can result in loss of the limb if not treated.
The term intermittent claudication means leg pain
sufficient to cause the patient to stop, which is
produced by exercise and relieved by rest, and is
caused by arterial occlusive disease.
The pain is reproducibly caused by a given
degree of exercise and relieved within minutes by
rest.
One who claudicates is called a claudicant,
although the term claudicator is also frequently
used.
* 5% of males older than 50 years have
intermittent claudication
* 5% of claudicants progress to critical
ischaemia each year
* 75% of patients remain stable or show clinical
improvement
* Peripheral vascular disease is an
independent risk factor for cardiovascular disease
* At 5 years of follow-up
o 10% claudicants and 50% of those
with critical ischaemia have had an
amputation.
o 20% claudicants and 50%of those
with critical ischaemia have died usually
from ischaemic heart disease
This presentation is based on TASC
recommendations.
TASC - TransAtlantic Inter-Society
Consensus about management of
peripheral arterial disease (pad).
Claudication:
* Calf or thigh pain precipitated by
exercise
* Usually occurs after predictable
distance
* Described as 'cramp' or 'tightness'
* Relieved by rest
* Progression of symptoms is important
- worsening or improvement
* Impact on social function should be
identified
* Need to differentiate form spinal stenosis
- Also cause exercise induced leg pain
- Usually associated with neurological
symptoms and relieved by spinal flexion
- Peripheral pulses can be present in
patients with intermittent claudication
Peripheral arterial disease is not simply a hemodynamic
disorder. Additional factors are involved in the
pathogenesis of this disease.
Key factors include deconditioning, because these
patients are very inactive.
In addition, several studies have shown skeletal muscle
injury in patients with chronic arterial occlusive disease.
This injury has been characterized as a distal axonal
denervation leading to loss of muscle fibers and mild
atrophy of the affected muscle.
Fontaine classification of chronic leg
ischaemia
Stage I Asymptomatic
Stage II Intermittent claudication
A - walking distance >200m
B - walking distance <200m
Stage III Ischaemic rest pain
Stage IV Ulceration or gangrene, or
both
Angiogram showing bilateral occlusions of superficial femoral
arteries in thighs.
Collaterals arising from the profunda femoris artery can
functionally bypass this occlusion
Although many patients with claudication
remain stable, about 150-200 per million of
the population progress to critical limb
ischaemia (Fontaine III or IV) each year.
Many patients with critical limb ischaemia
can undergo revascularisation, which has a
reasonable chance of saving the limb.
History and examination
Diagnosis of peripheral arterial disease is
based mainly on the history, with
examination and ankle brachial pressure
index being used to confirm and localise the
disease
Peripheral arterial disease is a marker for
systemic atherosclerosis; the risk to the limb
in claudication is low, but the risk to life is
high.
Patients with intermittent claudication
experience cramping pain and
weakness in the calf and/or buttocks on
walking.
The pain usually disappears when
standing still and occurs at a fixed
distance walked before it recurs. It
comes on more rapidly when walking
uphill than on the flat.
Disease of the superficial femoral artery in
the thigh results in absent popliteal and foot
pulses and often causes calf claudication.
Disease of the aorta or iliac artery results in
a weak or absent femoral pulse, often
associated with a femoral bruit.
Disease at this level may cause calf, thigh,
or buttock claudication.
The history of claudication due to chronic
peripheral arterial occlusive disease is
characteristic and reproducible enough that
diagnosis usually can be made on the basis of
interrogation alone in the large majority of
patients. The Edinburgh claudication
questionnaire is highly specific (91%) and
sensitive (99%) for the condition.
The differential diagnosis includes both venous
and neurogenic claudication (nerve root
compression from a herniated disc or osteophytic
encroachment, or spinal cord stenosis).
Differential diagnosis of intermittent claudication
Characteristic
Intermittent claudication
Venous claudication
Nerve root pain
Quality of pain
Cramping
"Bursting"
Electric shock-like
Onset
immediate,
Gradual, consistent
Gradual, can be immediate Can be
inconsistent
Relieved by
Location
Standing still
Muscle groups
(buttock, thigh, calf)
Legs affected Usually one
Elevation of leg
Whole leg
Usually one
Sitting down, bending
forward
Poorly localised, can
affect whole leg
Often both
In general it is important to document:
— The location of the pain or discomfort.
— The duration of the symptom.
— Whether it is worsening or improving with time and
whether conservative therapy has had an effect.
— The distance the patient can now walk before (a)
experiencing the discomfort and (b) being forced to stop.
— The elapsed time after exercise is stopped before the
pain is relieved.
— The type of rest or position of patient (standing at
rest, sitting, lying) necessary to relieve the pain.
— Whether the pain returns after the same time and
distance if exercise is then resumed.
There is therapeutic importance to uncovering
underlying conditions that may aggravate though
not cause claudication, for example, anemia,
polycythemia, cardiac failure or arrhythmia, and
chronic pulmonary disease with hypoxemia.
Also, it should be remembered that
atherosclerosis is often present at several arterial
sites in the same patient, and PAD is often
accompanied by coronary artery disease or
carotid artery disease.
Physical examination
In evaluating claudication, a complete
examination of the patient is necessary
to detect potentially important
contributing factors that may
significantly impact management.
The physical examination should not be limited to a
vascular examination focused primarily on the extremity
circulation, as described in the following passages.
At the very least, it should assess the circulatory system
as a whole.
Discovery of systemic hypertension, cardiac murmurs or
arrhythmias, carotid bruits, signs of respiratory
impairment, anemia, or an abdominal aortic aneurysm
are the rewards of such an examination.
The skin of the legs, especially the feet and nails,
should be examined for changes in color and
temperature and other abnormalities
such as swelling, scars of previous ulceration,
and the presence of any of the so called “trophic”
changes associated with severe chronic
ischemia: thin, dry skin, loss of hair or
subcutaneous fat, and thickened nails.
Close to one third of patients with PAD have clinically
significant coronary atherosclerosis, and in those who
are claudicants it is often masked by exercise
restrictions. Occult MI is not uncommon, and a resting
ECG should be routinely obtained on all new patients
with IC if no recent report is available.
Approximately one fourth of PAD patients have
hypertension, and in these consideration should be
given to the possibility of renal artery narrowing.
Finally, approximately 10% to 15% have
cerebrovascular disease, mostly in the form of carotid
stenosis.
Walking Distance
Because the major clinical manifestation of IC is walking
impairment, walking distance is the primary objective
parameter for the assessment of treatment.
The usual treadmill exercise test to assess the
hemodynamic significance of arterial occlusive disease
in the lower extremities is performed in a vascular
diagnostic laboratory. The patient walks at a standard
speed and grade on a treadmill until claudication pain is
experienced or a time limit has been reached, for
example, 5 minutes at 3.5 km/h on a 12% incline.
The latter is equivalent to walking nearly 600 meters at
average speed.
Pulse palpation
Pulse palpation should be correlated
with claudication distance and location
of pain, usually indicates the location
and severity of the responsible arterial
lesion(s).
Auscultation of bruits may give
additional useful information.
Method of palpating dorsalis pedis pulse.
Examine pulse from the foot of the bed, keeping the
fingers flat for the dorsalis pedis , while applying
counterpressure with the thumb.
The dorsalis pedis artery lies superficially on the dorsum
of the foot, although its position varies considerably.
Method of palpating posterior tibial pulse.
Examine pulse from the foot of the bed, using the
fingertips for the posterior tibial, while applying
counterpressure with the thumb.
The posterior tibial artery lies deeper behind the medial
malleolus. Many healthy people have only one foot
pulse.
Method of palpating popliteal artery with patient's knee slightly
flexed.
Use thumbs to apply counterpressure while palpating the artery,
which lies deep in popliteal fossa, with fingers.
The popliteal pulse can be difficult to palpate in muscular patients.
A prominent popliteal pulse suggests the possibility of a popliteal
aneurysm.
Method of palpating femoral pulse in skin crease of
groin.
Counterpressure on the lower abdomen pushes
the skin crease towards the inguinal ligament and
reduces the risk of missing the puls
For example, a decreased amplitude of the femoral
pulse, along with a loud bruit proximally over the iliac
artery, usually indicates the presence of a significant iliac
stenosis. With complete occlusion, no pulsation or bruits
are present.
Monitoring pulses and bruits after a brief period of
exercise occasionally will provide additional information
if pulses disappear or bruits accentuate.
Simply combining the pulse findings with the location
and severity of the ischemic symptoms allows the
presence and segmental location of the responsible
arterial lesions to be predicted with accuracy
comparable to that of noninvasive testing (close to 90%).
Hand-held doppler
* Reflection of an ultrasound wave off a
stationary object does not change its frequency
* Reflection off a moving object results in a
change of frequency
* The change in frequency is proportional to
velocity or blood flow
* Hand held 8 MHz doppler probe is used to
assess arterial system
* Can be used to measure arterial
pressures
* Measurements can be made at rest and
after exercise
* In normal individual lower limb
pressures are greater than upper limb
* Ankle-brachial pressure index (ratio of
best foot systolic to brachial systolic
pressure)
The ankle-brachial pressure index (ABPI)
should be measured in both legs in all new
patients with intermittent claudication, in
both legs.
A blood pressure cuff is placed on the upper
arm and inflated until no brachial pulse is
detected by the Doppler device.
The cuff is then slowly deflated until a
Doppler-detected pulse returns (the systolic
pressure).
This maneuver is repeated on the leg, with
the cuff wrapped around the distal calf and
the Doppler device placed over the dorsalis
pedis or posterior tibial artery.
The ankle systolic pressure divided by the
brachial systolic pressure gives the ABI.
We can also wrap the caff around other
parts of the leg (e.g. tigh) and take
segmental limb pressures.
ABI
First, it objectively confirms or rules out the
existence of hemodynamically significant
occlusive disease between the heart and the
ankle, which in almost all cases lies distal to the
renal arteries.
Second, it provides a rough measure of the
severity of the occlusive disease for correlation
with the patient’s symptoms.
Third, it can serve as an aid in differential
diagnosis, in that patients with exercise-related
leg pain of other causes will either have a normal
ankle pressure or a degree of reduction which
does not fit with the severity of disability.
Finally, the ABPI can detect lesser disease in the
contralateral extremity, which may not be
suspected because it is masked by the more
severe symptomatic leg.
Special considerations in evaluating diabetic
patients.
Patients with long-standing diabetes commonly
develop calcified, incompressible vessels, which
cause false high SLP measurements, particularly
at the ankle level.
The presence of this artifact is obvious when the
measured SLP are all unbelievably high (eg, 300
mm Hg) or ABPI is greater than 1.5, but subtler
degrees can be misleading.
Relationship of clinical features to ABPI
* In normal individuals pressures do not
fall flowing exercise
* In claudicants the ABPI falls and
recovery is delayed
* In diabetic lower limb pressures are
falsely elevated due to calcification in the
vessel wall
* ABPI in patients with claudication is not well
correlated with their exercise performance on a
treadmill
.
Toe pressures
* Provides accurate assessment of distal
circulation
* Not influenced by calcification in pedal
vessels
* Medical calcification particularly seen in
diabetics
* Normal toe pressures are 90-100 mmHg
* Toe pressure less than 30 mmHg suggests
critical limb ischaemia
Noninvasive localization of lesions
If it is desirable to localize and gauge the severity
of occlusive arterial lesions to assist in planning
an intervention; then duplex scanning or magnetic
resonance angiography (depending on local
availability, experience, and cost) can be used as
a preliminary, noninvasive examination before
angiography. In many cases, the information
supplied by simpler tests such as segmental limb
pressure or pulse volume recording is adequate
for decision making.
It should be noted that common practice in relation to
noninvasive investigations used in patients differs widely
between Europe and North America.
For example, segmental limb pressures (SLP),
pulse volume recordings (PVR), and velocity waveform
analysis (VWF) are much more widely used in North
America, where there is already considerable
experience in their use and interpretation.
In Europe, however, a preferred alternative to these tests
is duplex scanning.
Segmental limb systolic pressure measurement (SLP)
SLP is now widely used because it accurately detects and
segmentally localizes hemodynamically significant
large-vessel occlusive lesions in the major arteries between the
heart and the measuring point.
Segmental measurements at levels down the leg (upper and lower
thigh and calf), in addition to the ankle, are obtained in the same
fashion as the ankle pressure (AP).
A sphygmomanometer cuff is placed at a given level with a
Doppler probe over one of the pedal arteries, and the systolic
pressure in the major arteries under the cuff is measured.
The location of occlusive lesions is apparent from the pressure
gradients between the different cuffs.
Segmental plethysmography or pulse volume recordings
(PVR)
A plethysmograph is any instrument that detects and graphically
records volume change.
To perform segmental plethysmography, any instrument that
measures the relative change in volume associated with each
cardiac cycle in the segment of limb encircled by a
plethysmographic sensor may be used.
In common practice calibrated air-filled cuffs, much like
sphygmomanometer cuffs, are employed.
They are placed around the leg at selected locations and
connected to a plethysmograph, which produces a “pulse volume
recording” (PVR).
Doppler Velocity Wave Form (VWF)
This is used in some Vascular Diagnostic Laboratories, instead of
PVR, to complement SLP.
Here, arterial VWF is recorded using a continuous-wave Doppler
over the femoral, popliteal, posterior tibial, and dorsalis pedis
arteries.
Similar to the interpretation of PVR, qualitative differences in the
magnitude and contour of VWF between two
adjacent recording points identifies the presence of an occlusive
lesion in the intervening arterial segment.
However, VWF recording and analysis is very operator
dependent, and for that reason PVR are preferred by most.
Duplex ultrasound
* Combined pulsed doppler and real time
B mode ultrasound
* Allows imaging of vessels and any
stenotic lesion
* Flow and pressure wave form can be
also be assessed
Doppler wave forms from normal and
diseases arteries
In normal individuals a 'triphasic' wave
is obtained
* Rapid antegrade flow during
systole
* Transient reverse flow in early
diastole
* Slow antegrade flow in late diastole
An arterial stenosis results in the
following distal to the lesion:
* Decreased rate of rise of the
antegrade flow
* A reduced amplitude of the forward
velocity
* Loss of reverse flow (i.e. a
'biphasic' wave form)
* At the stenosis velocity is increased
* Severe stenosis result in a monophasic
waveform
* Duplex ultrasound has sensitivity of
80% and specificity of 90% for stenotic
lesions in the femoral and popliteal
segments
Magnetic resonance angiography
* Time of flight sequences
* No contrast required.
CT angiography
* Required intravenous contrast and
ionising radiation
* Spiral CT and reconstruction can
provide detailed images
* Particularly useful for the
assessment of aneurysmal disease
Angiography
Angiography in a patient with intermittent
claudication is usually indicated only when a
decision has been made to intervene, should a
suitable lesion be identified.
* Usually performed using digital subtraction
techniques
* Catheter inserted using Seldinger technique
* Femoral artery is commonest site of venous
access
* Generally safe procedure performed under
local anaesthetic
•Potential complications include
* Contrast-related
o Anaphylactic reaction
o Toxic reactions
o Deterioration in renal function
* Technique-related
o Haematoma
o Arterial spasm
o Sub-intimal dissection
o False aneurysm
o Arteriovenous fistula
o Embolisation
o Infection
Blood tests
The following blood tests should be
performed in all new patients presenting
with intermittent claudication:
— complete blood count (hemoglobin,
hematocrit, white cell count);
— platelet count;
— fasting blood glucose or hemoglobin A1c;
— creatinine;
— fasting lipid profile;
— urinalysis (for glycosuria/proteinuria).
The following laboratory investigations
should be performed selectively in atypical
patients (eg, those with early age of onset,
atypical distribution of occlusive lesions,
personal or family history of thrombotic
events, lack of any of the common risk
factors for, or a family history of,
atherosclerosis, unexpected failed
interventions):
— hypercoagulability screen;
— homocysteine levels.
Homocysteine
Recently, several reports have shown a strong
association between increases in plasma homocysteine
concentration and PAD.
This may be an important risk factor in patients younger
than 50 years who present with claudication.
ECG
A baseline resting electrocardiogram is
recommended in new patients with intermittent
claudication, but in the absence of family history,
risk factors, or suggestive symptoms or signs,
there is as yet no good evidence for routine
further investigation of other circulations in such
patients. Patients with peripheral arterial disease
have a high associated prevalence of coronary,
cerebrovascular, and renal artery disease.
Patients with symptoms or signs suggesting
atherosclerotic disease in other regions will need
further investigations and special assessment.
Algorithm for investigation of suspected
intermittent claudication
Investigation
There are many causes of leg pain that can occur
in the presence of asymptomatic peripheral
vascular disease. Therefore, the absence of
pulses does not necessarily imply a causal link.
Furthermore, the presence of pulses at rest does
not exclude symptomatic peripheral vascular
disease. A good history together with an ankle
brachial systolic pressure index of less than 0.9
confirms the diagnosis.
Duplex ultrasound scanning is useful for
delineating the anatomical site of disease in
the lower limb. Many hospitals still use
arteriography for this purpose or when the
results of duplex scanning are equivocal.
This invasive and expensive investigation
should not be requested unless there is a
plan to proceed with revascularisation, if
possible.
Algorithm for treatment of intermittent claudication
Principles of treatment
Intermittent claudication seems a relatively
benign condition, although severe
claudication may preclude patients from
manual work.
The risk of generalised vascular disease is
probably more important.
Patients with claudication have a three
times higher risk of death compared with
age matched controls.
The overriding issue in the management of patients
presenting with IC is that they are at significant risk of
developing severe and often fatal cardiovascular
complications; thus, their most serious problem is not
the limitation of walking, even though that may be their
only symptom.
The first priority in designing a treatment plan for these
patients is to try to modify the known risk factors for the
progression of atherosclerosis and development of
atherothrombotic complications.
It is important to explain to the patient the rationale for
this strategy and that it is not designed to improve the
claudication distance.
Modification of risk factors is therefore vital to
reduce death from myocardial infarction and
stroke.
All patients should be advised to stop smoking
and take regular exercise.
They should also be screened for hyperlipidaemia
and diabetes.
Obesity reduces exercise capacity, and losing
weight will improve the walking distance.
Only when best medical treatment has been
instituted and given sufficient time to take effect
should endovascular or surgical intervention be
considered, as most patients' symptoms improve
with best medical treatment to a point where
invasive intervention is no longer needed.
Best medical treatment is beneficial even in
patients who eventually need invasive treatment,
as the safety, immediate success, and durability
of intervention is greatly improved in patients who
adhere to best medical treatment.
Factors which may influence the decision to
treat claudication
For
Severe symptoms
Job affected
No better after exercise training
Stenosis or short occlusion
Proximal disease
Unilateral disease
Against
Short history
Continued smoking
Severe angina or chronic obstructive
airways disease
Long occlusion
Distal disease
Multilevel disease
Exercise programmes
A program of exercise therapy (preferably supervised)
should always be considered as part of the initial
treatment for patients with intermittent claudication.
A recent meta-analysis of 21 supervised exercise
programmes showed that training for at least six months,
by walking to near maximum pain tolerance, significantly
improved pain free and maximum walking distances.
Treadmills can be used for objective
measurement of walking distance and for
exercise training
Smoking cessation in peripheral arterial
disease
All patients with peripheral arterial disease should
be strongly and repeatedly advised to stop
smoking. Cessation rates are likely to be
enhanced by a special program.
Unfortunately, rates of cessation after simple oral
or written advice from a doctor are as low as 13%
at two years.
Randomised controlled trials have shown that
nicotine replacement treatment approximately
doubles the cessation rate in unselected
smokers.
Control of diabetes in peripheral arterial
disease
Patients with diabetes and peripheral arterial
disease should have aggressive control and
normalization of blood sugar.
Fasting blood sugars should range from 80 to 120
mg/dL, and postprandial sugars should be <180
mg/dL; hemoglobin A1c should be <7.0%.
Diabetic foot care in peripheral arterial
disease
All diabetic patients with peripheral arterial
disease should receive special advice and
regular supervision to minimize the risks of
developing diabetic foot complications.
Lipid control in peripheral arterial disease
Because of the high incidence of coexistent
coronary disease and similar mortality risk to
coronary patients, patients with peripheral arterial
disease with a low-density lipoprotein (LDL)
cholesterol level greater than 125 mg/dL should
be placed on therapy. In the first instance, a diet
should be tried. If this fails to achieve a goal of
LDL cholesterol level less than 100 mg/dL, then
medications should be tried.
Control of hypertension in peripheral arterial
disease
Peripheral arterial disease patients with hypertension
should have this risk factor controlled.
Reducing blood pressure to <140/85 mm Hg
ACE (angiotensin converting enzyme) inhibitors should
be considered in all patients, even if normotensive.
However, clinicians should be aware that when drug
therapy results in a large decrease in systemic blood
pressure, some patients may experience a slight
worsening of their claudication symptoms.
Hypercoagulable states in intermittent
claudication
Patients with intermittent claudication who
have a hypercoagulable state and proven
arterial or venous thrombosis should be
anticoagulated with acenocumarol
(Europe),coumarins (USA).
Antiplatelet therapy in peripheral
arterial disease
All patients with peripheral arterial disease
(whether symptomatic or asymptomatic)
should be considered for treatment with
low-dose aspirin, or other approved
antiplatelet (unless contraindicated), to
reduce the risk of cardiovascular morbidity
and mortality.
Patients with intermittent claudication mostly receive
drug treatment for coexisting disease (eg, hypertension),
risk factor modification (eg, hyperlipidemia), and as
prophylaxis against thrombotic events associated with
atherosclerosis (eg, antiplatelet drugs).
No pharmacological agent has proved efficacious
enough in providing significant reduction or elimination
of symptoms of claudication to gain widespread
acceptance and use for improving walking.
However, a number of types of drugs have been
promoted for this indication,
Pharmacotherapy for symptoms of
intermittent claudication
Although some controlled clinical trials with
pentoxifylline, naftidrofuryl, buflomedil, and
recently cilostozol, have shown statistically
significant improvement in walking distance, the
average benefit was small. Greater benefit,
observed in a minority of patients, may warrant a
short course of therapy with continued use of
such agents if sufficient benefit is observed.
Recent clinical trials have shown a greater
benefit of cilostazol for both walking
distance and quality of life, which may
warrant more widespread use. However,
currently there are insufficient data to
recommend the routine use of
pharmacotherapy in all patients with
claudication.
Cytokines - future treatment?
Vascular endothelial growth factor (VEGF) and basic
fibroblast growth factor (bFGF) are mitogenic agents for
the development of new collateral channels in models of
peripheral ischemia.
VEGF has been shown to augment collateral vessel
development and increase capillary density in skeletal
muscle in a rabbit model.
This effect has been observed when the VEGF protein is
administered by intraarterial infusion and when the DNA
encoding for VEGF is given by intramuscular injection.
Early phase I and phase II trials are now in progress to
determine whether this novel therapy has a clinical
application in patients with claudication and severe leg
ischemia.
Invasive therapy
Before offering a patient with intermittent
claudication the option of any invasive therapy,
endovascular or surgical, the following
considerations must be taken into account:
— a predicted or observed lack of adequate
response to exercise therapy and risk factor
modification;
— the patient must have a severe disability, either
being unable to perform normal work or having
very serious impairment of other activities
important to the patient;
— absence of other disease that would limit
exercise even if the claudication was improved
(eg, angina or chronic respiratory disease);
— the individual’s anticipated natural history and
prognosis;
— the morphology of the lesion must be such that
the appropriate intervention would have low risk
and high probability of initial and long-term
success.
The decision to consider a patient for
interventional therapy is arrived at by the
patient balancing existing disability against
the procedural risk and likelihood of longterm success of an intervention.
Choosing between techniques with
comparable short- and long-term
benefit
When two techniques of revascularization
(endovascular and open surgery) give
equivalent short-term and long-term benefit,
the technique with the least morbidity and
mortality must be used first.
Cost also should be considered.
Endovascular techniques
The number of percutaneous transluminal
angioplasties performed for claudication has risen
steeply in recent years. In some situations
endovascular techniques have virtually replaced
conventional surgery. Percutaneous transluminal
angioplasty seems best suited for stenoses or
short occlusions of the iliac and superficial
femoral vessels. Angioplasty carries a small but
definite risk of losing the limb because of
thrombosis or embolisation, and patients should
be informed of this risk.
Percutaneous transluminal angioplasty:
* Angioplasty of the aorto-iliac segment
has a 90% 5 year patency
* Angioplasty of the infra-inguinal vessels
has a 70% 5 year patency
* Best results seen with short segment
stenoses less than 2 cm long
•Complications occur in less than 2% of
patients
o Wound haematoma
o Acute thrombosis
o Distal embolisation
o Arterial wall rupture
Short occlusion of left popliteal artery treated by percutaneous transluminal angioplasty.
The balloon catheter is passed through the occlusion over a guide wire and inflated.
Appearance after angioplasty
PTA with implantion stent
Metallic stents push back the atheroma and
improve on the initial lumen gain after angioplasty
alone.
The indications for iliac stents include a residual
stenosis or dissection after angioplasty and long
occlusions, but there seems little evidence to
justify their routine use.
Deployment of stents more distally has produced
disappointing results due to high restenosis rates.
Occlusion of the right common iliac artery before
(left) and after (right) insertion of stent
Morphological stratification of iliac lesions
Abbreviations: CIA, common iliac artery; EIA, external
iliac artery; CFA, common femoral artery.
Treatment of choice for TASC type A and D aortoiliac
lesions:
Endovascular procedure is the treatment of choice for
type A lesions, and surgery is the procedure of choice for
type D lesions.
Role of stenting for residual pressure gradient,
dissection, or elastic recoil:
Stenting improves the technical and initial clinical
success in cases of residual pressure gradient or
dissection after angioplasty, or in cases of elastic recoil.
Between these two groups are types B and C lesions, in
which no firm recommendations
can be made about the preferred interventional option.
At present, endovascular treatment is more commonly
used in type B lesions, and surgical treatment is more
commonly used in type C lesions.
It should be emphasized that there is no sufficient solid
evidence to make any firm recommendations,
particularly in the case of types B and C.
The indications for iliac artery stenting, which are
generally accepted in clinical practice, are as follows:
— insufficient hemodynamic result of PTA due to elastic
recoil based on residual pressure gradient;
— massive, lumen-obstructing dissection;
— treatment of chronic occlusions;
— iliac artery ulceration associated with symptoms;
— restenoses after previously performed PTA;
— complex lesions for which primary stenting may give
more satisfactory results.
Morphological stratification of femoropopliteal lesions
Treatment of choice for TASC type A and D
femoropopliteal lesions:
Endovascular procedure is the treatment of
choice for type A lesions, and surgery is the
procedure of choice for type D lesions.
Femoropopliteal stenting in PAD:
Femoropopliteal stenting as a primary approach
to the interventional treatment of intermittent
claudication or CLI is not indicated. However,
stents may have a limited role in salvage of acute
PTA failures or complications.
Morphological stratification of popliteal and tibial lesions
Unlike the aortoiliac and femoropopliteal
segments, the infrapopliteal vessels are usually
not treated unless there is critical acute or chronic
limb ischemia.
Therefore, most of the experience in
infrapopliteal endovascular recanalization has
come from patients with limb-threatening
ischemia.
Surgery
Surgery is rarely necessary in patients with IC;
in fact, surgery should be avoided initially and
other options pursued in most patients.
Ordinarily, if exercise therapy fails or is rejected
by the patient for other reasons, these patients
may try pharmacotherapy or be referred for
imaging to evaluate the possibility of balloon
angioplasty.
If these options are not possible, or fail, surgery
may be considered.
The decision involves an individualized risk to
benefit analysis, balancing the benefit of relieving
that particular patient’s disability against the
immediate risks (morbidity/mortality/technical
failure) and the risk of late failure of the proposed
surgical procedure.
This weighing of risk and benefit must be settled
in the patient’s favor.
Endarterectomy is an acceptable option when
truly localized disease is present, for example,
the narrowing of the aorta and common iliac
arteries alone.
Otherwise, patency rates are unsatisfactory, and
bypass grafting is more appropriate.
The traditional operation for aortoiliac occlusive
disease is an aortofemoral bypass, performed
with a prosthetic graft because of the large caliber
of the vessels.
Axillobifemoral bypass is an extra-anatomic bypass that
reduces the risk of proximal reconstruction by avoiding
an abdominal incision with aortic dissection and
clamping.
However, its primary patency is inferior to aortobifemoral
bypass and, in spite of improving results, it is still not
recommended for the treatment of IC.
Infrainguinal bypass procedures are best performed with
autogenous vein grafts, although the results of prosthetic
bypasses are acceptable if the graft does not cross the
knee joint.
Considering the quite dismal results of percutaneous
angioplasty and stenting for disease in the crural
arteries, autogenous vein bypass to the distal vessels
should be considered as first-line therapy in patients with
limb-threatening ischemia and distal disease.
Polyester (Dacron) aortobifemoral bypass grafts have
five year patency rates of over 90% but are associated
with a mortality of up to 5%. Complications include graft
infection and postoperative impotence.
Femoropopliteal bypass grafting, using autologous long
saphenous vein, polyester, or polytetrafluoroethylene
(Goretex) yields patency rates of less than 70% at five
years. The early patency of prosthetic grafts seems
similar to that of vein grafts, although the long term
results seem less good. Femoropopliteal bypass grafts
should rarely be used for patients with claudication.
Surgery for intermittent claudication:
— Surgery should be offered to treat severe
symptoms only after other forms of medical
therapy have been recommended and have
either failed or been rejected for good reason.
— If used, surgery for IC should employ the
procedure offering extended clinical benefit with a
high benfit-to-risk ratio.
— If necessary, surgery is the treatment of choice
of type D lesions but may be used also in type B
and C lesions.
Types of bypass graft include:
* Biological grafts
o Autografts
+ Long saphenous vein - in-situ or
reversed
+ Internal mammary artery
o Allografts
+ Dacron coated umbilical vein
* Synthetic grafts
o Dacron - woven or knitted +/albumin coated
o Woven grafts - smaller pores. No
preclotting required
o Velour - Polyfluorotetraethylene
(PTFE)
Choice of graft material
* Determined by long term patency rates
* Autologous vein is best graft material
but not always available
* Interposition of vein between PTFE
graft and artery at distal anastomosis can
improve long term patency
Comparative three year patency of vein and
synthetic grafts:
Above knee anastomosis
Below knee anastomosis
Vein PTFE
85-90% 75-80%
70-75% <50%
Benefits of vein versus prosthetic grafts for
above-knee femoropopliteal bypass.
In favor of vein
— Better long-term patency rates
— Avoidance of "staged" approach to femoral
popliteal
— Need for other use overestimated.
— Lower risk of graft infection
In favor of prosthesis
— Close to equivalent long-term patency rates
— Fewer wound complications
— Vein available for secondary or coronary
bypass
— Shorter operative time
Reasons for graft failure
* Less than 30 days - technical failure
* 30 days to 1 years - neointimal
hyperplasia at distal anastomosis
* More than 1 years - progression of
distal disease
Success of treatment for intermittent
claudication
— Objective outcome: relevant improvement in
walking distance as measured by a standardized
exercise test;
— Symptomatic outcome: improvement on a
validated disease-specific health status
questionnaire;
— General quality of life: improvement on a
validated generic health status questionnaire;
— Postrevascularization: objective proof of
patency of any revascularized segment (ideally
with imaging).
Use of prophylactic antibiotics with
prosthetic grafts
Patients undergoing prosthetic grafts should
have prophylactic antibiotic therapy
perioperatively
Antiplatelets as adjuvant pharmacotherapy
after revascularization
Antiplatelet therapy should be started
preoperatively and continued as adjuvant
pharmacotherapy after an endovascular or
surgical procedure. Unless subsequently
contraindicated, this should be continued
indefinitely. Caution should be used in patients in
whom use of anticoagulants is proposed.
Surveillance program for bypass grafts and
transluminal angioplasty
Patients undergoing bypass graft placement in
the lower extremity for the treatment of
claudication or limb-threatening ischemia should
be entered into a surveillance program. This
program should consist of:
— interval history (new symptoms);
— vascular examination of the leg with palpation
of proximal, graft, and outflow vessel pulses;
— periodic measurement of resting and, if
possible, post-exercise ankle-brachial indices;
— duplex scanning of the entire length of the
graft, with calculation of peak systolic velocities
and the velocity ratios across all identified
lesions;
Surveillance programs should be performed in
the immediate postoperative period and at regular
intervals for at least 2 year
Critical limb ischaemia
European Working Group on Critical Leg
Ischaemia (1991):
' Persistently recurring ischaemic rest pain
requiring regular adequate analgesia for
more than 2 weeks, or ulceration or
gangrene of the foot or toes,
with an ankle pressure of <50 mmHg
or toe pressures of <30 mmHg
or reduced TCPO2 (<30 mmHg) '
The term critical limb ischemia should be used for
patients with chronic ischemic rest pain, ulcers, or
gangrene attributable to objectively proven
arterial occlusive disease.
Most of these patients would be expected to
require a major amputation within the next 6
months to a year in the absence of a significant
hemodynamic improvement.
The term critical limb ischemia implies chronicity
and is to be distinguished from acute limb
ischemia.
Ischemic rest pain is characterized by severe, often
intolerable discomfort in the toes, forefoot, or heel that is
not relieved with the use of simple analgesics and only
responds to strong analgesics or opiates.
The pain is caused by ischemia, areas of tissue loss,
ischemic neuropathy, or a combination of these; it occurs
or worsens with reduction of perfusion pressure. In most
cases, walking capacity is very severely impaired, often
becoming almost impossible.
Ischemic rest pain most typically occurs at night but can
occur even during the day when the patient is resting
in supine position.
The pain is often severe, enough to wake the patient at
night and force him or her to rub the foot, get up, or take
a short walk around the room.
Partial relief may be obtained by the dependent position
and application of heat, whereas elevation and cold
increase the severity of the pain.
Often, patients sleep with their ischemic leg hanging
over the edge of the bed, or sitting in an armchair all
night; as a consequence, ankle and foot edema develop,
which further increases ischemia and pain.
Contracture of the knee and ankle joints may occur.
Gangrene can ensue when the reduced
arterial supply to the limb does not meet
with the metabolic demands of the ischemic
leg.
Late stages of CLI are characterized by
sensory loss and muscle weakness.
Infection may precede or may complicate
the nonhealing ulcer.
Most patients with CLI have multilevel,
multivessel disease, often with three-vessel
tibioperoneal occlusive disease.
Limb loss and cardiovascular mortality and
morbidity ensue rapidly if CLI is not treated.
Treatment options include surgical
revascularization, amputation, and endovascular
intervention.
The main treatment goals for CLI are limb
preservation, quality-of-life improvement, and a
reduction in cardiovascular complications from
the underlying diffuse atherosclerosis.
Patients with CLI usually not only have multilevel
disease in the involved extremity but also have a higher
likelihood of significant atherosclerosis in other
circulations, are a higher operative risk, and have a
more limited life expectancy compared with patients with
intermittent claudication.
Despite aggressive correction of distal ischemia, these
patients have a limited life expectancy, with less than
60% surviving more than 3 years after treatment.
Prompt referral of patients with critical limb
ischemia to a vascular specialist will improve the
chances of successful treatment.
Multidisciplinary approach is necessary in critical
limb ischemia:
Close cooperation between disciplines is
particularly desirable for the timely diagnosis and
treatment of both diabetic and nondiabetic
patients with critical limb ischemia.
Diabetes mellitus accentuates the risk of CLI by four
times, while continued tobacco abuse triples the risk.
Diabetes mellitus leads to rapid progression of
atherosclerosis at a premature age and preferentially
affects distal calf vessels.
This diffuse distal disease that is associated with
diabetes poses challenges for the surgeon or
endovascular specialist.
It has been estimated that 40% to 45% of all amputees
are diabetic.
A diabetic patient with CLI is 10 times more likely to
need amputation compared to a nondiabetic.
Gangrene associated with critical limb ischaemia
Foot ulcer associated with critical limb ischaemia
History and examination
Patients with critical limb ischaemia often
describe a history of deteriorating claudication,
progressing to nocturnal rest pain.
Ulceration or gangrene commonly results from
minor trauma.
Nocturnal rest pain often occurs just after the
patient has fallen asleep when the systemic blood
pressure falls, further reducing perfusion to the
foot.
Severe ischemia is often associated with atrophy of the
calf muscles, loss of hair growth over the dorsum of the
toes and foot is another relatively common sign of
severe arterial insufficiency; it often is accompanied by
thickening of the toenails secondary to slowness of nail
growth.
In more advanced cases, there is atrophy of the skin.
In severe, long-standing cases, the color of the skin is
usually extremely pale or cyanotic; there may be rubor
on dependency because of chronic dilatation of the
precapillary and postcapillary vessels.
Arterial ulcers usually involve the tips of the toes, the
heel of the foot, or wherever local pressure has caused
further decrease of perfusion.
Arterial ulcers typically have irregular borders; the base
of the ulcer is pale unless inflammation or infection, as
occurs in many cases, gives rise to local reactions such
as the production of exudate and pus.
These may lead to crust formation, covering the ulcer
surface, which in many cases leads to a decrease in
pain.
Gangrene usually affects the digits; in severe cases, it
may involve the distal parts of the forefoot.
Any minor local trauma such as cutting the toenails may
elicit formation of an ulcer and lead to gangrene; local
pressure (shoes, use of local heat) also can cause ulcer
and gangrene formation on any other place of the foot or
leg.
Gangrenous tissue, if not infected, has a tendency to
shrink and eventually lead to mummification of the part
affected.
Hanging the foot out of bed increases perfusion
and produces the typical dusky red hue due to
loss of capillary tone.
Elevation causes pallor and venous guttering.
Inspect the foot carefully for ulceration under the
heel and between the toes.
Swelling suggests deep infection. If you can
palpate foot pulses consider an alternative cause
of pain.
Patients with critical limb ischaemia require
urgent referral to a vascular surgeon.
Critically ischaemic foot displaying typical dusky
red hue on dependency (ischaemic rubor)
Critical limb ischaemia
* Characterised by rest pain
* Occurs when foot is elevated (e.g. in
bed)
* Improved with foot dependent
* May be associated with ulceration or
gangrene
* Foot pulses are invariably absent
Investigation
The ankle brachial systolic pressure
index is usually less than 0.5.
Arterial calcification may result in
falsely increased pressures, and
caution is needed when relying on
Doppler pressures alone, especially in
diabetic patients.
All patients with critical limb ischaemia should
ideally have arteriography with a view to
endovascular treatment, if feasible.
Duplex scanning may be used instead of
angiography and for mapping of the long
saphenous vein before distal bypass surgery.
Dependent Doppler or pulse generated run-off
can help to determine the most suitable artery to
receive a distal bypass graft if these cannot be
identified by angiography.
The diagnostic evaluation of patients with critical
limb ischemia should be directed toward the
following objectives:
— objective confirmation of the diagnosis;
— localization of the responsible lesion(s) and a
gauge of relative severity;
— assessment of the hemodynamic requirements
for successful intervention ( proximal, distal or
combined revascularization of multilevel disease);
— assessment of individual patient operative risk;
— assessment of atherosclerotic risk factors;
— assessment of atherosclerosis in other
systems.
To achieve the objectives listed previously,
the following investigations should be used
in patients with critical limb ischemia:
— complete clinical history and
examination, including the coronary and
cerebral circulation;
— basic hematologic and biochemical tests;
— resting ECG;
— ankle or toe pressure measurement or
other objective measures for the severity of
ischemia;
— imaging of the lower limb arteries in
patients considered for intervention;
— duplex scan of the carotid arteries should
be done in selected patients at high risk;
— a more detailed coronary assessment in
selected patients.
Principles of treatment
The same principles and techniques used to
treat claudication also apply to critical limb
ischaemia. However, critical limb ischaemia
is usually caused by multilevel disease,
which means that success rates are lower.
Treatment focuses on saving the limb,
although modification of risk factors remains
important.
The principal urgent components of basic treatment of
CLI are the control of pain and any infection in the
ischemic leg, prevention of progression of thrombosis if
this is thought to be a precipitating factor in the
ischemia, and the optimization of cardiac and respiratory
function.
While instituting basic treatment, the full precise
morphology of the PAD should be simultaneously
established by some form of imaging technique.
This will determine further management of the arterial
lesion.
If not promptly diagnosed and intervened
upon, CLI can lead to limb loss, gangrene,
sepsis, myocardial infarction, and death.
Studies have shown that within the first
several months of the diagnosis of CLI,
death occurs in 9%, myocardial infarction in
1%, stroke in 1%, amputation in 12%, and
persistent CLI in 18% of patients. One- and
2-year mortality rates are noted to be 21%
and 31.6%, respectively.
Algorithm for treatment of critical limb ischaemia
Control of Risk Factors
Patients with CLI have the same cardiovascular risk
factor profile as patients with claudication.
However, patients with CLI have a more diffuse and
extensive degree of atherosclerosis.
Therefore, their risk of cardiovascular events
and mortality is higher than that of patients with
claudication.
Despite the end-stage nature of this disease, aggressive
systemic risk factor modification is still warranted.
Ideally, the patient should be treated with the least risky
and least morbid but most successful and durable
procedure.
Comorbid risk factors will modify this ideal to give priority
to patient safety.
High-risk, frail patients may be best treated with less
invasive interventions, even though durability may not be
optimal.
In some patients, revascularization procedures should
be abandoned for primary amputation when patient
factors suggest extremely high morbidity and mortality or
the arterial anatomy predicts a poor outcome of
intervention.
Pain control in critical limb ischemia
Adequate treatment of ischemic pain is
mandatory in all patients with critical limb
ischemia and may require short-term use of
narcotics. Pain control should be
individualized and multifactorial. However,
pain control treatment should not delay
definitive treatment of the arterial lesion.
Opiates can be supplemented by nonsteroidal anti-inflammatory drugs if these
are not contraindicated. Apart from
rehydration, adequate analgesia alone may
be the best treatment for patients with
dementia or other severe comorbidity. If
opiate analgesia remains inadequate, then
lumbar sympathectomy (surgical or
chemical) or spinal cord stimulation may
help.
Topical therapy for ischemic ulceration
Topical therapy for ischemic ulceration
should be guided by the principles of wound
care.
The extremities should be kept clean, with
appropriate debridement.
Systemic antibiotic therapy in patients with
critical limb ischemia
Systemic antibiotics are required in patients who
develop cellulitis or spreading infection in
ischemic ulcers or gangrene but should not delay
more definitive treatment.
Use of prostanoids in critical limb
ischemia
Patients who have a viable limb in whom
revascularization procedures are
impossible, carry a poor chance of success
or have previously failed, and particularly
when the alternative is amputation, may be
treated with prostanoids.
Vasoactive drugs in treatment of critical limb
ischemia
Very few vasoactive drugs have been properly
investigated in patients with critical limb ischemia.
Because the results are unconvincing or
negative, current drugs cannot be recommended
in patients with chronic critical limb ischemia.
Endovascular treatment
Percutaneous transluminal angioplasty or
stenting of proximal disease may relieve
ischaemic rest pain, but healing of ulceration or
gangrene usually requires restoration of foot
pulses. This may necessitate extensive
angioplasty of the superficial femoral, popliteal,
and tibial arteries. Endovascular treatment can
also reduce the magnitude of subsequent
surgery.
Invasive treatment
The primary aim is revascularization to provide
sufficient blood flow to relieve the rest pain and
heal skin lesions. Most patients with CLI have
multisegment arterial disease, and often the
elimination of the most proximal obstruction might
be sufficient to achieve these aims.
The decision about what type of revascularization to
recommend ideally should be made by a
multidisciplinary team. Important issues that may
influence the recommended decision are:
— lesion morphology;
— risk of surgery for that particular patient;
— previous procedures (ie, bypass or angioplasty);
— patient’s life expectancy;
— local expertise and experience with particular surgical
or endovascular procedures.
In general, endovascular procedures are safer and
require shorter hospitalization compared with surgical
procedures.
Surgery
Patients with a pattern of arterial disease
considered unsuitable for endovascular
treatment will usually require surgery. Fit
patients with proximal disease benefit
greatly from aortobifemoral bypass grafting.
In unfit patients the options include
crossfemoral bypass for unilateral disease
or axillobifemoral bypass for bilateral
disease. These extra-anatomic procedures
have lower patency rates.
Surgical treatment options for aortoiliac disease
Many patients with distal disease will
require bypass grafting to the popliteal or
crural arteries below the knee. Autologous
vein grafts give the best patency rates (70%
at one year). Postoperative duplex
surveillance may improve patency by
permitting the detection and treatment of
vein graft stenoses before occlusion occurs.
Treatment of chronic critical leg ischemia
due to bypass graft occlusion
In patients with chronic critical leg ischemia,
surgical revision or graft replacement is the
preferred treatment for bypass graft occlusion.
Thrombolysis may be considered as a treatment
option in patients who present early after their
bypass graft occlusion where the limb is not
immediately threatened.
Lumbar sympathectomy in critical limb
ischemia
There is currently insufficient scientific
evidence for the selection of patients likely
to benefit from lumbar sympathectomy for
the treatment of critical limb ischemia.
Primary amputation
Primary amputation is defined as amputation of
the ischemic lower extremity without an
antecedent attempt at revascularization.
Amputation is considered as primary therapy for
lower limb ischemia only in selected cases.
Primary major amputation for critical limb
ischemia is indicated in advanced distal ischemia
with:
— unreconstructable arterial occlusive disease;
— necrosis of significant areas of weight-bearing
portion of the foot;
— fixed, unremediable flexion contracture of the
leg;
— a terminal illness or very limited life
expectancy because of comorbid conditions.
Secondary amputation
Unreconstructable vascular disease has become the
most common indication for secondary amputation,
accounting for nearly 60% of patients.
Persistent infection despite aggressive vascular
reconstruction is the second most common diagnosis.
The goals of secondary amputation are the relief of
ischemic pain, the complete removal of all diseased,
infected and necrotic tissue, the achievement of
complete healing and the construction of a stump
suitable for ambulation with a prosthesis.
It is the goal of amputation to obtain primary healing of
the lower extremity at the most distal level possible.
Preservation of the knee joint has enormous
advantages for wearing artificial limbs and
subsequent mobility. However, there is little point
in risking a non-healing, below knee amputation if
the patient seems unlikely to walk again.
Similarly, a patient with good prospects of
wearing an artificial limb will fare better with an
above knee amputation, if below knee amputation
seems unachievable. Local amputation of
ulcerated or gangrenous toes will not heal without
revascularisation.
Success of treatment for critical limb ischemia
should take into account an improvement in the
following:
Objective outcome: Complete healing of skin
lesions.
Standardized reporting criteria should include
technical success, hemodynamic testing,
procedural morbidity, limb function, and
amputation and mortality rates.
Technical success
Treatment of critical limb ischemia may require more
than one treatment modality, for example, thrombolytic
therapy and bypass grafting. Technical success does not
require the restoration of palpable pedal pulses in all
cases.
Many procedures, such as profundaplasty, may provide
increased distal perfusion through collateral beds.
Successful revascularization should lead to an increase
in ankle-brachial index
Limb salvage
Limb salvage after treatment for chronic critical limb
ischemia (CLI) is defined as preservation of a functional
foot. Because patients with advanced CLI may present
with ischemic gangrene of the toes, forefoot, or heel,
removal of this necrotic tissue is an essential part of any
therapeutic regimen.
Healing of wounds
Complete healing refers to a continuous viable, epithelial
covering over all previously open wounds.
Long incisions are often required for surgical
intervention.
Mortality rate
Procedural mortality is defined as death within 30 days
of the intervention or within the same hospitalization
as the intervention, if this is longer than 30 days.
Traditionally, the standard has been to report as
procedural mortality only those patients who die within
30 days of therapy.
Patients with CLI, however, often have severe comorbid
conditions that may be worsened by the procedure.