4.5 Lower extremity artery disease
4.5.6 Acute limb ischaemia (ALI)
Thrombotic or embolic causes can be involved. Artery disease progression, cardiac embolization, aortic dissection or emboliza- tion, graft thrombosis, thrombosis of a popliteal aneurysm, entrap- ment or cyst, trauma, phlegmasia cerulea, ergotism, hypercoagulable states, and iatrogenic complications related to cardiac catheterization, endovascular procedures, intra-aortic balloon pump, extra-corporeal cardiac assistance, as well as Table 7 Presentation of a patient with CLI
Assessment Feature Presentation to define CLI Remarks
History Duration of symptoms and clinical signs of CLI
>2 weeks Needs morphine analgesics to be controlled
Symptoms Rest pain Toe, forefoot Especially with elevation of limb (i.e. during night
sleep). Calf pain/cramps do not constitute clinical presentation of CLI
Ischaemic lesions Periungual, toes, heel, over-bone prominences
Infection Secondary complication: inflammation and
infection
Probe-to-bone test Positive test identifies osteomyelitis with high
specificity and sensitivity
Haemodynamics Absolute ankle pressure <50 mmHg
or <70 mmHg
Plus rest pain Plus ischaemic lesion(s)
Absolute great toe pressure <30 mmHg To be measured in the presence of medial calcinosis (incompressible or falsely elevated ankle pressure, ABI >1.40)
Transcutaneous partial oxygen pressure <30 mmHg Estimation of wound healing, considerable variability
ABIẳankle – brachial index; CLIẳcritical limb ischaemia.
Recommendations for the management of critical limb ischaemia
Recommendations Classa Levelb Refc For limb salvage,
revascularization is indicated whenever technically feasible.
I A 302, 331,
336 When technically feasible,
endovascular therapy may be considered as the first-line option.
IIb B 302, 331
If revascularization is impossible, prostanoids may be considered.
IIb B 338, 339
aClass of recommendation.
bLevel of evidence.
cReferences.
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Management of critical limb ischaemia
Urgent revascularization Rest pains
Feasible
Pain control (morphine), wound care, treatment of infection (antibiotics)
Unfeasible Pain control (morphine)
Endovascular revascularization
Favourable Clinical and non-invasive assessment of haemodynamic
result (Table 8 )
Control CVD risk factors, debridement, shoe adaptation (removal of weight-bearing stress
to lesion), surveillance
Control CVD risk factors, pain control (morphine),
wound care
Prostaglandins, consider spinal cord stimulation Surgical revascularization
Unfavourable Technical failure,
endovascular revascularization unsuitable
Amputation, rehabilitation Ischaemic lesion, gangrene
re-do procedure(endovascular or surgical)
Figure 4 Management of critical limb ischaemia. CVDẳcardiovascular disease.
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vessel closure devices are the potential causes of ALI. The viability of the limb is mostly threatened in this context. Quick and proper management is needed for limb salvage.
Once the clinical diagnosis is established, treatment with unfrac- tionated heparin should be given.6,342Analgesic treatment is often necessary. The level of emergency and the choice of therapeutic strategy depend on the clinical presentation, mainly the presence of neurological deficiencies, and the thrombotic vs. embolic cause. The clinical categories are presented inTable8.
An irreversible or unsalvageable extremity may require amputa- tion before deterioration of the patient’s clinical condition, although attempts are usually made to save the limb, or at least to limit the level of amputation. A viable limb mandates urgent imaging as well as the assessment of major co-morbidities. In the case of severely deteriorated renal function, detailed DUS imaging may replace angiography. In some cases, a clear cardiac embolization in poten- tially normal arteries can be treated by surgical embolectomy without previous angiographic imaging. Otherwise, given the emer- gency level of care, angiography can be performed with no previous vascular ultrasound to avoid therapeutic delays.
Different revascularization modalities can be applied (Figure5). The options for quick revascularization consist of percutaneous catheter- directed thrombolytic therapy, percutaneous mechanical thrombus extraction or thromboaspiration (with or without thrombolytic therapy), and surgical thrombectomy, bypass, and/or arterial repair.
The therapeutic strategy will depend on the type of occlusion (throm- bus or embolus) and its location, duration of ischaemia, co-morbidities, type of conduit (artery or graft), and therapy-related risks and outcomes. Owing to reduced morbidity and mortality com- pared with open surgery, endovascular therapy is the initial treatment of choice, especially in patients with severe co-morbidities, if the degree of severity allows time for revascularization, and pending local availability of an emergency interventional team. Treatment results are best with an ALI duration,14 days.6Intra-arterial throm- bolysis is the classic endovascular technique for thrombus removal.
Various techniques and different thrombolytic agents are currently
used.6Intrathrombotic delivery of the thrombolytic agent is more effective than non-selective catheter-directed infusion. Different devices aiming at mechanical removal of the clot have been developed and are commonly used alone or in combination with thrombolysis, with the main advantage of decreasing delay to reperfusion. The modern concept of the combination of intra-arterial thrombolysis and catheter-based clot removal is associated with 6-month amputa- tion rates,10%.6Systemic thrombolysis has no role in the treatment of patients with ALI.
Based on the results of old randomized trials,343–345there is no clear superiority of thrombolysis vs. surgery on 30-day mortality or limb salvage. Thrombolysis offers better results when applied within the first 14 days after the onset of symptoms. Thrombectomy devices have been proposed to treat ALI, but the benefits are not well documented. After thrombus removal, the pre-existing arterial lesion should be treated by endovascular methods or open surgery.
Based on clinical presentation and availability of an emergency centre, surgical revascularization should be preferred when limb ischaemia is highly threatening and catheter-based treatment attempts may delay revascularization. Lower extremity four- compartment fasciotomies are sometimes performed to prevent a post-reperfusion compartment syndrome, especially in the setting of class IIb and III ischaemia with surgical revascularization. In cases of viable limb, open or endovascular revascularization may not be possible, especially in the case of absent distal arteries, even after primaryin situthrombolysis; the only option then is to stabilize the ischaemic status with medical therapy (anticoagulation, prostanoids).
Table 8 Clinical categories of acute limb ischaemia
Grade Category Sensory loss
Motor
deficit Prognosis
I Viable None None No immediate
threat IIA Marginally
threatened
None or minimal (toes)
None Salvageable if promptly treated IIB Immediately
threatened
More than toes
Mild/
moderate
Salvageable if promptly revascularized III Irreversible Profound,
anaesthetic
Profound, paralysis (rigor)
Major tissue loss Amputation.
Permanent nerve damage inevitable
Adapted from Rutherfordet al., with permission.328
Recommendations for acute limb ischaemia
Recommendations Classa Levelb Refc Urgent revascularization
is indicated for ALI with threatened viability (stage II).
I A 6, 342
In the case of urgent endovascular therapy, catheter-based thrombolysis in combination with mechanical clot removal is indicated to decrease the time to reperfusion.
I B 6, 304
Surgery is indicated in ALI patients with motor or severe sensory deficit (stage IIB).
I B 304
In all patients with ALI, heparin treatment should be instituted as soon as possible.
I C -
Endovascular therapy should be considered for ALI patients with symptom onset
<14 days without motor deficit (stage IIA).
IIa A 6, 304
aClass of recommendation.
bLevel of evidence.
cReferences.
ALIẳacute limb ischaemia.
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Acute limb ischaemia
Viable
Heparin
Feasible—proceed
Feasible—proceed Feasible—proceed
Underlying lesion
Endovascular revascularization
Open revascularization
No Yes
Semi-urgent Imaging technique
Work-up Risk evaluation
Medical Treatment
Limb Threatening
Heparin
Unfeasible
Unfeasible Unfeasible
Decision making Emergent Imaging technique
Catheter directed Thrombolysis–thrombectomy
Irreversible
Amputation*
* Sometimes, differentiation between a salvageable and unsalvageable extremity is almost impossible. If the doubt is raised, any surgical or endovascular revascularization action is justified even in advanced profound ischaemia.
Figure 5 Decision-making algorithm in acute limb ischaemia.
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