
2/23

Definition of Acute Limb Ischemia

Suddendecrease of

arterial limb perfusioncausing threat to limb

viability


3/23

Etiology of acute limb ischemia

Acute arterial embolism:

Acute traumatic ischemia:

Of a relatively health arterial tree

Acute arterial thrombosis: Of a previously diseased arterial tree


4/23

Patho-pysiology

Acute EmbolicIschemia

Acute ThromboticIschemia

An embolussuddenly

occludes arelativelyhealthy

arterial tree

Atherosclerosiscauses

progressivenarrowing of the

arterial tree

Stimulatesdevelopment of

collaterals

Sluggish flow &rough surfacewill favor acute

thrombosis

It usuallyarrest atarterial

bifurcationAortic bifurcation

Iliac bifurcation

Femoral bifurcation

Popliteal trifurcation

An embolus can originate from the heart (MS with atrial fibrillation,MI with mural thrombus)

or dilated diseased arteries(aortic aneurism)


5/23

It is important to differentiate between embolic &thrombotic ischemia: Because the

managementis different

Clinical Features Suggestive of acute Embolism:

Sudden onset of symptomsKnown embolic source

Absence of previous claudication

Normal pulse in the other limb


6/23

The severity of acute ischemia depends on:

a) Capability of existing collaterals to carry blood around the acute obstruction

(collaterals are more developedin patients with preexistingchronic ischemia)Accordingly, arterial embolism is

more likely to produce suddensymptoms & severe ischemiathen arterial thrombosis

b) The location of obstruction in relation to the number of axial arteries

Postgraduates

Aorta & common iliac One axial a. with limited collateral pathways

Internal & external iliac Two axial aa. With better collateral potentials

Two axial aa. With better collateral potentialsSuperficial & deep femoral

Popliteal artery One axial a. with limited collateral pathways

Three axial aa. with better collateral potentialsTibial arteries

c) The extent of obstructionThe larger the obstruction, the more collaterals arelost

d)The duration

Flow distal to the obstruction is sluggish. If collaterals cannotincrease the flow above a critical point, a stagnation clot will

develop in the distal arterial tee. This the reason why heparinshould be given as early as possible

For Example:

Popliteal a occlusion (a

single axial a.) results insevere ischemia, whileposterior tibial occlusionmay be asymptomatic ifother leg arteries arepatent


7/23

Definition:Suddendecrease of arterial limb perfusion causing threat to limb viability

Etiology:1-Embolic (Rh.heart w mitral stenosis & AForIschemic heart w acute myocardialinfarction & mural thrombusorextra-cardiac embolism from aneurismal arteries)

2-Thrombotic acute ischemia on top of atherosclerotic arterial stenosis

Pathology: onset of symptoms is more acute in embolic ischemia (absent collaterals)

Other factors determine the severity of acute ischemia

Clinical Picture

Management


8/23

Clinical Evaluation of Acute Ischemia(Clinical Picture)

Symptoms of acute ischemia:

Pain: Diffuse foot & leg severe aching pain of acute onset (more acute inembolic ischemia)

Pain may diminish in intensity by time if collaterals open improving circulation, or ifischemia progresses causing ischemic sensory loss

Coldness is an early symptom

Numbness followed by sensory loss (late)

Muscle weakness (heavy limb) followed by paralysis (late)


9/23

Clinical Evaluation of Acute Ischemia(Clinical Picture)

History

Aim of your questions

1- To know whether these symptoms are of acute ischemia or not

(DD of acute ischemia : acute DVT[phlegmasia], hypo-perfusion states[e.g. heart

failure specially if associated with chronic ischemia]

2- To know the severity of acute ischemia

(ask about symptoms of different classes of acute ischemiasee later)

3- To look for the underlying etiology

(ask about Rh. Heart Ds, claudication, recent arterial interventione.g. cardiac cath.,

risk factors for atherosclerosis:hypertension, diabetes, smoking, hyperlipedemia,family history of cardio-vascular disease)


10/23

Clinical Evaluation of Acute Ischemia (Clinical Picture)

Signs of acute ischemia

5PsPain: symptom

+

Pulseless

Pale

Parathesia

Paralysis

Inspection

COLOR:

Early: pale

Later: cyanosed mottling fixedmottling & cyanosis

Pallor

Reversiblemottling

An area offixed cyanosissurrounded by

reversiblemottling

Empty veins:compare the Rt.(ischemic) & Lt.(normal)

Fixedmottling &cyanosis


11/23



5PsPain: symptom

+

Pulseless

Pale

Parathesia

Paralysis

Palpation

Femoral Popliteal

Posterior tibial Dorsalis pedis

Palpate peripheral pulses, compare with theother side & write it down on a sketch

Temperature: the limb is cold with a level oftemperature change (compare the two limbs)

Slow capillary refilling of the skin afterfinger pressure


12/23



5PsPain: symptom

+

Pulseless

Pale

Parathesia

Paralysis

Palpation

Loss of sensory function

Numbness will progress to anesthesia

Progress of Sensory loss

Light touch

Vibration sense

Proprioreception

Deep pain

Pressure sense

Late


13/23



5PsPain: symptom

+

Pulseless

Pale

Parathesia

Paralysis

Palpation

Loss of motor function:

Indicates advancedlimb threateningischemia

Late irreversibleischemia: Muscle turgidity

Intrinsic foot muscles are affected

first, followed by the leg muscles

Detecting early muscle weakness isdifficult because toes movements areproduced mainly by leg muscles

Postgraduates


14/23

Classes of Acute Ischemia

Clinical Findings Doppler Prognosis

Class Sensoryloss

Motorweakness

Arterialsignals

VenousSignals

I.Viable -ve -ve audible audible Not immediatelythreatened

II.aMarginalthreat

Minimalsensory loss

No muscleweakness

Often notaudible

audible Salvageable if promptttt (there is time for

angiography)

II.b Immediatethreat

Rest pain wsensory lossmore than toes

Mild tomoderate

Usuallynot

audible

audible Salvageable withimmediate ttt (no time

for angiography)

III.Irreversible Severeanesthesia

Paralysis wmuscle rigor

Inaudible Inaudible Not salvageable,permanent N. & muscle

damage ,needs amputation

Postgraduates


15/23






Clinical Picture

Management

The limb is described as having 5 Ps :

Pain, Pale, Pulseless, Parathesia, Paralysis


16/23

Investigations of acute limb ischemia

The severity and duration of ischemia at the time of presentation provides a

narrow margin of time for investigations

Doppler US

It is important to look forarterial Doppler signalsto assess the level of

obstruction & severity ofischemia

The presence of pedal signals

usually indicates that there istime for conventionalarteriography & proper patientpreparation

The ABI is not of value inacute ischemia. If it can bemeasured, the limb is notthreatened

Postgraduates


17/23

Arteriography

Investigations of acute limb ischemia

Patients with high clinical probability of embolic ischemia do NOT need angiography

If the differentiation betweenembolic & thrombotic ischemia isnot clear clinically, and if the limb

condition permits,

DO ANGIOGRAPHY

Value of angiography

Localizes the obstruction

Visualize the arterial tree & distalrun-off

Can diagnose an embolus:

Sharp cutoff, reversed meniscus or clot

silhouette

Popliteal embolism

Reversed meniscus sign

Lt. iliac embolism

Clot silhouette


18/23

Treatment of acute limb ischemia

A Once you diagnose

Immediate anticoagulation with heparin to avoid clotpropagation

Appropriate analgesia

Simple measures to improve existing perfusion:

Keep the foot dependant

Avoid pressure over the heal

Avoid extremes of temperature (cold induces vasospasm, heal raises themetabolic rate)

Maximum tissue oxygenation (oxygen inhalation)

Correct hypotension

Start treatment of other associated cardiac conditions (CHF, AF)


19/23


B Catheter directed thrombolysis

Indications:

1. Viable or marginally threatened limb (class I, IIa)

2. Recent acute thrombosis (not suitable for embolism or old thrombi)

3. Avoid patients with contraindications

Agents used: Streptokinase,Urokinase, tissue plasminogen

activator

Contraindications:

Absolute:

1. Cerebro-vascular stroke within previous 2 months

2. Active bleeding or recent GI bleeding within previous 10 days

3. Intracranial trauma or neurosurgery within previous 3 months

Relative:

1. Cardio-pulmonary resuscitation within previous 10 days

2. Major surgery or trauma within previous 10 days

3. Uncontrolled hypertension


20/23


C Surgery

1- Acute embolism: Catheter embolectomy under local anesthesia

2- Immediate surgical revascularization is indicated in class IIb, or class I, IIa

when thrombolysis is not possible or contraindicated

A combination of different procedures can be done:

Arterial exploration at different sites

Arterial thrombectomy

Bypass surgery based on pre-operativeangiography if available or intra-operativeangiography


21/23

Following revascularization:

The sudden return of oxygenated blood to the acutely

ischemic muscles generates & releases oxygen free radicalsthat causes cellular injury and severe edema

Compartment syndrome

& muscle necrosis

ttt

FasciotomyLongitudinal incision of the skin & deep fascia to release pressure over swollen muscles


22/23

Amputation:

Done for irreversible ischemia with permanent tissuedamage (turgid muscles, fixed cyanosis)

The level of amputation is decided according to the level of

palpable pulse.

Palpable popliteal pulse -------------- Below knee amputation

Absent popliteal pulse ---------------- Above knee amputation


23/23






Clinical Picture

Investigations

The limb is described as having 5 Ps :

Pain, Pale, Pulseless, Parathesia, Paralysis

Doppler to evaluate level & degree of ischemia

Conventional angiography in class I & IIa

Intraoperative angiography in class IIb

Treatment HeparinCatheter directed thrombolysisOperative revascularizationAmputation in irreversible ischemia

Documents

Acute Limb Ischemia Site