Acute Limb Ischemia

Definition, Etiology & Patophysiology

Clinical Evaluation & Classes

Management

Ali SABBOUR
Prof. of Vascular Surgery, Ain Shams University
Definition of Acute Limb Ischemia

Sudden decrease of
arterial limb perfusion
causing threat to limb
viability
 Etiology of acute limb ischemia

Acute arterial embolism: Of a relatively health arterial tree

Acute arterial thrombosis: Of a previously diseased arterial tree

Acute traumatic ischemia:

 Acute Thrombotic
Acute Embolic
Ischemia Patho-pysiology Ischemia

An embolus can originate from the heart (MS with atrial fibrillation,
MI with mural thrombus) or dilated diseased arteries (aortic aneurism)
Atherosclerosis
An embolus causes
suddenly progressive
occludes a narrowing of the
relatively arterial tree
healthy arterial
tree
Stimulates
development of
It usually
collaterals
arrest at
arterial
bifurcation Sluggish flow &
rough surface
Aortic bifurcation
will favor acute
Iliac bifurcation thrombosis
Femoral bifurcation
Popliteal trifurcation
It is important to differentiate between embolic &
thrombotic ischemia: Because the
management
is different
Clinical Features Suggestive of acute Embolism:
Sudden onset of symptoms
Known embolic source
Absence of previous claudication
Normal pulse in the other limb
Definition: Sudden decrease of arterial limb perfusion causing threat to limb viability
Etiology: 1-Embolic (Rh.heart w mitral stenosis & AF or Ischemic heart w acute myocardial
infarction & mural thrombus or extra-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
Clinical Evaluation of Acute Ischemia
(Clinical Picture)
Symptoms of acute ischemia:

Pain:
Pain Diffuse foot & leg severe aching pain of acute onset (more acute in
embolic ischemia)
Pain may diminish in intensity by time if collaterals open improving circulation, or if
ischemia progresses causing ischemic sensory loss

Coldness is an early symptom

Numbness followed by sensory loss (late)

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

 Postgraduates

The severity of acute ischemia depends on:

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

(collaterals are more developed
b) The location of obstruction in relation to the in number of axial
patients arteries
with preexisting
chronic ischemia)
c) The extent of obstruction Accordingly, arterial embolism is
more likely to produce sudden
Aorta & common iliac One axial a. with limited collateral pathways
The larger the obstruction,
symptoms the&more collaterals
severe ischemiaare
d) The duration lost then arterial thrombosis
Internal & external Two axial aa. With better collateral potentials
iliac Flow distal to the obstruction is sluggish. If collaterals cannot
For Example:
Example
increase the flow above a critical point, a stagnation clot will
Popliteal a occlusion (a
Superficial & deep femoral developTwo
in axial
the distal arterial
aa. With tee. Thispotentials
better collateral the reason why heparin
single axial a.) results in
should be given as early as possible severe ischemia, while
Popliteal artery One axial a. with limited collateral pathways posterior tibial occlusion
may be asymptomatic if
other leg arteries are
patent
Tibial arteries Three axial aa. with better collateral potentials
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 ischemia –see later)

3- To look for the underlying etiology

(ask about Rh. Heart Ds, claudication, recent arterial intervention e.g. cardiac cath.,
risk factors for atherosclerosis: hypertension, diabetes, smoking, hyperlipedemia,
family history of cardio-vascular disease)
 Clinical Evaluation of Acute Ischemia (Clinical Picture)

Signs of acute ischemia Inspection

5Ps COLOR:
Fixed Early:
Early pale
Pain: symptom
mottling &

+
Later:
Later cyanosed mottling fixed
cyanosis mottling & cyanosis

An area of
Pallor
Pale fixed cyanosis
surrounded by
reversible
Pulseless Reversible
mottling
mottling
Parathesia
Empty veins:
compare the Rt.
Paralysis (ischemic) & Lt.
(normal)
 Clinical Evaluation of Acute Ischemia (Clinical Picture)

Signs of acute ischemia Palpation

5Ps
Pain: symptom

+ Femoral Popliteal

Pale

Pulseless Posterior tibial Dorsalis pedis

Palpate peripheral pulses, compare with the

Parathesia other side & write it down on a sketch

Temperature:
Temperature the limb is cold with a level of
Paralysis temperature change (compare the two limbs)

Slow capillary refilling of the skin after

finger pressure
 Clinical Evaluation of Acute Ischemia (Clinical Picture)

Signs of acute ischemia Palpation

5Ps Loss of sensory function

Pain: symptom Numbness will progress to anesthesia

+ Progress of Sensory loss

Pale Light touch

Vibration sense
Pulseless
Proprioreception

Parathesia
Deep pain Late
Paralysis Pressure sense
 Clinical Evaluation of Acute Ischemia (Clinical Picture)

Signs of acute ischemia Palpation

5Ps Loss of motor function:

Pain: symptom Indicates advanced limb threatening

+
ischemia
Late irreversible ischemia: Muscle turgidity

Pale
Postgraduates
Pulseless
Intrinsic foot muscles are affected
Parathesia first, followed by the leg muscles
Detecting early muscle weakness is
Paralysis difficult because toes movements are
produced mainly by leg muscles
 Postgraduates

Classes of Acute Ischemia

Clinical Findings Doppler Prognosis

Class Sensory Motor Arterial Venous

loss weakness signals Signals
I. Viable -ve -ve audible audible Not immediately
threatened
Minimal No muscle Often not audible Salvageable if prompt
II.a Marginal
sensory loss weakness audible ttt (there is time for
threat angiography)

II.b Immediate Rest pain w Mild to Usually audible Salvageable with

threat sensory loss moderate not immediate ttt (no time
more than toes audible for angiography)

III.Irreversible
III. Severe Paralysis w Inaudible Inaudible Not salvageable,
anesthesia muscle rigor permanent N. & muscle
damage , needs amputation
Definition: Sudden decrease of arterial limb perfusion causing threat to limb viability
Etiology: 1-Embolic (Rh.heart w mitral stenosis & AF or Ischemic heart w acute myocardial
infarction & mural thrombus or extra-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

The limb is described as having 5 Ps :

Pain, Pale, Pulseless, Parathesia, Paralysis

Management
Investigations of acute limb ischemia
The severity and duration of ischemia at the time of presentation provides a
narrow margin of time for investigations

Postgraduates

Doppler US The presence of pedal signals

It is important to look for usually indicates that there is
time for conventional
arterial Doppler signals arteriography & proper patient
to assess the level of preparation
obstruction & severity of The ABI is not of value in
acute ischemia. If it can be
ischemia measured, the limb is not
threatened
Investigations of acute limb ischemia
Arteriography

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

If the differentiation between

embolic & thrombotic ischemia is
not clear clinically, and if the limb
condition permits,

DO ANGIOGRAPHY
Value of angiography
Localizes the obstruction
Visualize the arterial tree & distal
run-off
Can diagnose an embolus:
Popliteal embolism Lt. iliac embolism
Sharp cutoff, reversed meniscus or clot
silhouette Reversed meniscus sign Clot silhouette
 Treatment of acute limb ischemia
A Once you diagnose

Immediate anticoagulation with heparin to avoid clot

propagation
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 the
metabolic rate)
• Maximum tissue oxygenation (oxygen inhalation)
• Correct hypotension
Start treatment of other associated cardiac conditions (CHF, AF)
 Treatment of acute limb ischemia
B Catheter directed thrombolysis Agents used: Streptokinase,
Urokinase, tissue plasminogen
Indications: activator

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

Contraindications:
Absolute:
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:
Relative
1. Cardio-pulmonary resuscitation within previous 10 days
2. Major surgery or trauma within previous 10 days
3. Uncontrolled hypertension
 Treatment of acute limb ischemia
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-operative
angiography if available or intra-operative
angiography
Following revascularization:
The sudden return of oxygenated blood to the acutely
ischemic muscles generates & releases oxygen free radicals
that causes cellular injury and severe edema

Compartment syndrome
& muscle necrosis

ttt

Fasciotomy
Longitudinal incision of the skin & deep fascia to release pressure over swollen muscles
 Amputation:

Done for irreversible ischemia with permanent tissue

damage (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
Definition: Sudden decrease of arterial limb perfusion causing threat to limb viability
Etiology: 1-Embolic (Rh.heart w mitral stenosis & AF or Ischemic heart w acute myocardial
infarction & mural thrombus or extra-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
The limb is described as having 5 Ps :
Pain, Pale, Pulseless, Parathesia, Paralysis

Investigations Doppler to evaluate level & degree of ischemia

Conventional angiography in class I & IIa
Intraoperative angiography in class IIb

Treatment Heparin
Catheter directed thrombolysis
Operative revascularization
Amputation in irreversible ischemia