6. EMBOLISM VS THROMBOSIS :
Embolism Thrombosis
Sources Frequently detected Not specified
Onset Sudden Acute
Site Normal vessels Stenosis, calcified vessels
Previous history A known embolic source, such as
cardiac arrhythmias, lv clots
Symptoms of chronic ischemia
Findings Normal pulses in uneffected limb Evidence of PVD
Multiplicity Multiple sites Single site
Angiography Multiple occlusions, no collaterals Diffuse atherosclerosis
Collaterals present
7. PATHOPHYSIOLOGY :
• Insufficient oxygenated blood to meet the metabolic demand of the tissues.
• Severity Depends on :
Degree of obstruction
Site of occlusion
Presence of collaterals
Affected tissues
Systemic perfusion, such as cardiac output and peripheral vascular resistance
Ischemia → Aerobic to anaerobic metabolism → Lactate production→ Depletion
of ATP → Leakage of extracellular calcium into muscle cells → Cell death.
8. The tissues most sensitive to ischemia are :
• Peripheral nerves (Irreversible damage after 6 hours)
• Skin
• Subcutaneous tissues
• Skeletal muscle (up to 10 hrs)
9. SYMPTOMS :
• PAIN :
• PALLOR
• POIKILOTHERMIA
• PULSELESS
• PARASTHESIA
• PARALYSIS
• Either constant or elicited by passive movement .
• Embolic occlusions : Sudden & severe intensity.
10. SYMPTOMS :
• PAIN
• PALLOR
• POIKILOTHERMIA
• PULSELESS
• PARASTHESIA
• PARALYSIS
An area of fixed
cyanosis surrounded
by reversible mottling
Pallor
Empty veins:
compare with normal
limb
11. SYMPTOMS :
• PAIN :
• PALLOR
• POIKILOTHERMIA :
• PULSELESS :
• PARASTHESIA
• PARALYSIS
Sudden loss of previously palpable pulse.
Slow capillary refilling after finger pressure
Bounding water hammer pulses proximal
to occlusion
The limb is cold.
12. SYMPTOMS :
• PAIN
• PALLOR
• POIKILOTHERMIA
• PULSELESS
• PARASTHESIA
• PARALYSIS
Loss of sensory function
Numbness will progress to anesthesia
Progress of Sensory loss
Light touch
Vibration sense
Proprioception
Deep pain
Pressure sense
13. SYMPTOMS :
• PAIN
• PALLOR
• POIKILOTHERMIA
• PULSELESS
• PARASTHESIA
• PARALYSIS :
• Fine movement affected first
• Loss of motor function: Indicates advanced limb
threatening ischemia
• Late irreversible ischemia: Muscle turgidity.
14. EVALUATION & DIAGNOSIS:
• Diagnosis of ALI is primarily clinical.
• In suspected ALI, initial clinical evaluation should
Rapidly assess limb viability
Potential for limb salvage.
• The severity of the ischemia will dictate the extent of diagnostic tests performed
for systemic risk factor assessment.
17. CT ANGIOGRAM : IOC
Advantages :
• Non invasive.
• Accurate analysis of the location, extent & grading of steno-obstructive disease.
• Differentiate Embolic & Thrombotic cause if not clear clinically.
• Conditions of vessels.
• Visualizes distal arterial tree and distal cut off.
Disadvantages:
Still uses ionizing radiation & iodinated contrast agent.
18. ARTERIOGRAM (DSA):
• Used to be gold standard test for road mapping before surgery.
• Replaced by CTA and MRA.
Advantages:
• Accurately detects level and nature of occlusion.
• May be able to immediately start therapeutic intervention.
Disadvantages:
• Lack of collaterals and associated spasm limits visualization of more distal vessels.
• Incidence of contrast nephrotoxicity.
• Invasive.
• Expensive.
19. DUPLEX USG :
• Can be considered as a second line of imaging if angiography is not possible for
infrainguinal arterial occlusion.
Advantages:
• Noninvasive.
• Fairly accurate for infrainguinal disease, especially for bypass grafts.
Disadvantages:
• Suprainguinal arterial occlusions and distal run-off vessels not well visualized.
• Calcifications of arterial walls can create artifacts and obscure visualization.
20. MR ANGIOGRAM :
Advantages:
• Less contrast load than angiography.
• Non ionizing.
• Better for distal small and pedal vessels as compared to CT angiography.
• Can be used as an alternative imaging modality for patients at high risk for CIN.
Disadvantages:
• Higher cost, large number of artifacts.
• More time consuming than CT.
• Precipitates nephrogenic systemic fibrosis.
21. MANAGEMENT OF ALI :
Treatment selection :
• Revascularization can range from CDT to surgical thromboembolectomy.
• Selection of intervention : One that provides the most rapid restoration of arterial
flow with least risk to the patient.
• Prolonged duration of ischemia (> 6-8 hrs) is the most common factor in patients
requiring amputation for treatment of ALI.
Main target: Rapid restoration of arterial flow with least risk to patient.
22. CLASS I :
• Class I ALI may require only medical therapy, such as anticoagulation.
• Revascularization, if contemplated, can be performed electively.
• Can be either thrombolytic or open surgical intervention.
Treatment selection depends on :
Duration of ALI.
Location & cause.
Presence or absence of underlying PVD.
Patient’s general medical condition.
23. CLASS II A
• Class II A ALI requires a flexible approach to intervention.
• Require urgent revascularization to preserve the functional integrity.
• Duration of symptoms is of prime importance.
• Surgical intervention reserved in patients unresponsive to lytic therapy.
• Percutaneous endovascular options are more effective in patients with ischemia
<2 weeks duration, > 2 weeks are better served by surgical revascularization.
• Prospective studies comparing thrombolytic & surgical intervention favor the
initial use of thrombolytic therapy ( < 2 weeks).
24. CLASS II B
• Manifested by both sensory & motor deficits, requires emergency
revascularization (<6 hours).
• Advances in CDT & PMT devices have shortened the time to reperfusion.
• Consequently, these techniques are increasingly being used as first line therapy in
patients with Class IIb ALI.
• Surgical revascularization has been preferred.
25. CLASS III
• Class III ALI manifests as :
Profound neurologic deficit & muscle rigidity.
Absence of arterial & venous doppler ultrasound signals in the affected limb.
• In Class III ALI, revascularization is usually futile & may have adverse systemic
effects such as cardiac arrest due to acidosis and hyperkalemia.
Primary amputation should be considered.
26. INITIAL MANAGEMENT :
• Routine blood studies should be performed before heparin is administered.
CBC
Creatinine Phospokinase: Predictive of major amputation.
Hypercoagulable state work up.
Renal function tests
Lipid profile
FBS and HbA1c
ECG
Chest X Ray
2D ECHO
27. MANAGEMENT : EARLY HEPARINIZATION
• One of the mainstays in the treatment of ALI.
• Immediate full-dose heparinization .
• Prevents proximal and distal thrombus propagation.
• IV unfractionated heparin 80 U/kg bolus, followed by infusion of 18 U/kg/hour.
• To maintain aPTT ratio 2-3.
• Known history of HIT or an anti-thrombin III deficiency, alternative agents, such as direct
thrombin inhibitors (lepirudin or argatroban) can be used.
28. OTHER MEASURES :
• Adequate analgesia.
• IV fluid resuscitation, urine output monitoring.
• Oxygen supplementation.
• Correction of underlying electrolyte imbalances.
• Systemic antiplatelets therapy initiation.
• Limb placed in dependent position and kept warm.
30. CATHETER DIRECTED THROMBOLYSIS :
CDT has become the preferred treatment : :
• Viable or marginally threatened limbs
(Classes I and IIA).
• ALI < 2weeks.
• Acutely thrombosed grafts and occluded
stents.
Goal : To achieve regional thrombus dissolution with minimal systemic fibrinolysis.
31. REGIMENS FOR INFUSION :
Low Dose Regimen :
• 1-mg bolus, followed by a continuous infusion of 0.5 to 1 mg/h.
• Can run for 10 to 12 hours or overnight
• Repeat arteriogram performed the following day.
High Dose Regime :
• 10-mg pulse-spray bolus of tPA over 5 minutes, followed by a continuous
infusion at 0.05 mg/kg per hour with a maximum dose of 4 mg/h.
• High-dose infusion is continued for 6 hours before angiography is again
performed.
32. CHECK LIST :
• Serum fibrinogen level every 4 hours , discontinue infusion < 100 mg/dL.
• If hypofibrinogenemia, thrombolytic catheter is removed to prevent thrombosis around the catheter.
• All patients are kept nbm in a critical care setting.
• Observed for clinical or laboratory evidence of local or systemic bleeding.
• Heparin is administered through the proximal side port of the 5 Fr sheath at 300 to 500 units/h to
prevent perisheath thrombosis.
33. Catheter Directed Thrombolysis :
• Advantages:
• Direct delivery of drug into existing thrombus.
• Reduces thrombolytic drug dosages.
• Lyses clot in both large & small vessels.
• Lower incidence of reperfusion syndrome.
• Done via percutaneous approach with local anaesthesia.
• Disadvantages: Takes >24 hours to be effective, Risk of major bleeding (6-9%).
34. CONTRAINDICATIONS TO THROMBOLYSIS :
Absolute Contraindications :
• Established cerebrovascular events within
last 2 months.
• Active bleeding diathesis.
• Recent (<10 days) GIT bleeding.
• Neurosurgery within last 3 months.
• Intracranial trauma within last 3 months
• Intracranial malignancy or metastasis
Relative Major Contraindications :
• Major nonvascular surgery or trauma < 10 days
• Cardiopulmonary resuscitation within last 10 days
• Uncontrolled hypertension (>180 mmHg systolic or
>110 mmHg diastolic)
• Puncture of noncompressible vessel
• Recent eye surgery
Minor Contraindications :
• Hepatic failure
• Bacterial endocarditis
• Pregnancy
• Diabetic haemorrhagic retinopathy
35. RESULTS & PROGNOSIS :
The factors that portend a higher likelihood of success are:
1) Recent graft occlusion (<14days).
2) Guide wire traversal of occluded graft.
3) Graft patency of atleast 1 year prior to thrombotic event
4) Presence of remediable lesion that may be treated.
CDT leads to resolution of thrombus in 75% -90% of patients.
36. • Factors associated with poor outcome include:
Diabetes.
Active smoking.
Prosthetic graft.
24 months vessel patency rate CDT for native arterial occlusions :
79% if an underlying lesion was identified & treated.
9.8% when no lesion was identified.
For bypass graft thrombotic events, CDT patency rates are between 10% - 40%
at 2 years.
38. INITIAL THROMBOLYTIC THERAPY OR PRIMARY
OPERATION FOR ALI : TRIALS
SERIES NUMBER OF
PATIENTS
PERIOD
(MONTHS)
THROMBOLYSIS
AMPUTATION (%)
THROMBOLYSIS
DEATH (%)
OPERATION
AMPUTATION (%)
OPERATION
DEATH (%)
UNIVERSITY
OF
ROCHESTER
114 12 25 16 48 42
STILE TRIAL 393 6 12 6.5 11 8.5
TOPAS
TRIAL - II
544 12 15 20 13.1 17
39. PHARMACO MECHANICAL THROMBECTOMY :
• Several mechanical clot removal devices are used in conjunction with lytic agents.
Ultrasound energy (EkoSonic Endovascular System )
Power pulse injection (AngioJet ).
Used to accelerate the speed of thrombolysis.
• The resultant decrease in the dose of lytic agents & duration of thrombolysis results :
Minimize the bleeding risk associated with standard CDT
Shorten the time to reperfusion.
40. • EKOS EkoSonic Endovascular System :
• The EKOS Catheter (EKOS Corporation/BTG, Bothell,
Washington) uses ultrasound to facilitate clot
penetration by the lytic agent.
• This is due to thrombus deformation by the
ultrasound waves, which exposes a greater surface
area to the infused lytic agent.
• Clinical success rate is 90% in some studies.
In studies, thrombus exposed to ultrasound absorbs
48% more tPA in 1 hour
84% more tPA in 2 hours
89% more tPA in 4 hours
41. • AngioJet Thrombectomy System :
• The AngioJet Thrombectomy System (Boston Scientific, Marlborough,
Massachusetts) has been approved by the U.S. FDA for use in PAD.
• AngioJet has the longest clinical history.
• Use of “Power 4420 pulse-spray” mode, tPA is actively injected into thrombus.
• Allowed to dwell for 5 to 20 min & aspirated, along with liquefying the thrombus.
• The AngioJet system has 3 major components: The catheter, pump set & drive unit.
42. • Embolization & hemolysis are known complications of this technique.
• Pump set & drive unit : Produce a controlled, high-
velocity saline jet (350 to 450 km/h) that is
redirected at the tip of a dual-lumen catheter.
• Saline solution from the pump drive unit is driven at
50 to 60 mL/min and 8000 to 10,000 pounds per
square inch, resulting in a high-velocity jet at the
catheter tip.
• Thrombus surrounding the catheter tip is
fragmented & rapidly evacuated through the
effluent lumen.
43. Advantages:
• Disrupts the thrombus- allows better penetration of the clot by a thrombolytic agent.
• Reduces thrombolytic dosing
• Reduces therapy time- increasingly being used in class IIb
• Done via percutaneous approach with local anesthesia
• Less vessel injury.
Disadvantages:
• Can be used only large vessel
• Expensive device
44. PERCUTANEOUS MECHANICAL THROMBECTOMY :
1. HYDRODYNAMIC DEVICES :
• Remove thrombus from the peripheral
arteries through the use of a stream of
fluid & hydrodynamic forces to extract
the thrombotic material from the lumen.
• The AngioJet system as described
previously uses a dedicated fluid delivery
machine to achieve thrombus removal
without the use of adjunctive TPA.
45. 2. ROTATIONAL/MECHANICAL DEVICES :
• A variety of “brushes,” rotating wires & mechanical thrombectomy devices that
fragment thrombus with or without aspirating the fragments have been designed
to establish arterial recanalization.
Cleaner rotational thrombectomy system (Argon Medical, Plano, Texas)
Arrow-Trerotola thrombectomy device (Teleflex Inc, Morrisville, North Carolina).
• Gained a foothold in the treatment of dialysis access graft occlusion.
• Reluctance to use them in native arteries for fear of injuring the vessel wall.
• Potential limitation : Risk of distal embolization of macroparticles of thrombus.
46. 3.THROMBUS ASPIRATION DEVICES :
• It involves moving a catheter over a wire while aspirating thrombus with a large syringe.
Aspire max 5 mechanical thrombectomy system ( Control Medical Tech )
Diver CE Aspiration Catheter ( Medtronic )
• The size of thrombus fragments that can be aspirated is limited by the distal diameter of
the catheter tip .
• Very useful when small amounts of fresh thrombus are in the distal circulation.
• To treat embolization after recent angioplasty.
• However, this technique has a low success rate when used as stand-alone therapy.
47. Advantages :
• Initial rapid thrombus debulking.
• Significantly reduces the dose & duration of thrombolytic agents.
• Decreases the risk of hemorrhagic complications.
• Exposure of the residual thrombus & distal vessels to thrombolytic agents.
• Result in considerable cost savings.
• Finally, may be used as sole therapy with contraindications to thrombolytics.
48. COMPLICATIONS :
• Distal embolization.
• Trauma to the endothelium.
• Hemolysis with hemoglobinemia & hemoglobinuria can occur.
• Volume overload occurs if volume of intravascular irrigation is excess.
In vitro studies comparing endothelial denudation with AngioJet & Fogarty
thrombectomy catheter have demonstrated significantly greater mean endothelial
loss in vessels treated with the Fogarty balloon catheter (58.0% vs 88.0%).
49. TRIAL RESULTS :
Kasirajan et al. compared patients with ALI treated with the AngioJet catheter,
controls treated with standard open surgical techniques.
• The 65 patients in the AngioJet group received stand-alone treatment (n = 21) &
subsequent adjunctive pharmacologic thrombolysis (n = 44).
• They were compared with 79 patients who underwent surgical revascularization.
• No difference was noted in the 1-month amputation rate (11% vs. 14%; P = .57);
however, a lower rate of early mortality was observed in the AngioJet group
(7.7% vs. 22%; P = .037).
• A lower rate of local (P = .002) and systemic (P < .001) complications was
observed for the AngioJet treatment group.
50. The EKOS Infusion Catheter has been investigated as an option for treating ALI.
• In a series of 25 patients undergoing treatment with the EKOS, total clot
removal was achieved in 22 (88%) after 16.9 hours (range: 5 to 24 hours) using
a mean dosage of 17 mg (range: 5 to 25 mg) rtPA.
• In 8 patients, total clot removal of the main lesion was achieved after 6 hours
with 6 mg of rtPA.
Braithwaite et al. managed 15 patients of ALI with mechanical thrombectomy
& anticoagulation alone (surgical or thrombolytic contraindications)
• Resulting in dismal 30-day limb salvage and mortality rates of 33% and 60%
respectively.
51. Dutch Randomized Trial (DUET) : A prospective randomized study comparing
the EKOS system with standard CDT.
• 32 patients randomized to standard thrombolysis and 28 randomized to
ultrasound accelerated thrombolysis.
• Time to achieve complete lysis & the overall lytic dose were significantly less in
the ultrasound-accelerated thrombolysis group.
• No difference in technical success, 30-day death or serious adverse events & in
30-day patency.
52. SURGICAL REVASCULARIZATION :
Balloon catheter thrombectomy :
• First introduced by Fogarty et al. in
1963, has been the cornerstone of
therapy for the surgical management of
ALI.
• Severe ALI (class IIb) requires urgent
intervention & surgical therapy has
remained the treatment of choice.
53. BALLOON CATHETER THROMBECTOMY :
• Local or general anesthesia
• The artery (usually the larger proximal), exposed
and held in slings and longitudinal or transverse
incision given.
• Fogarty balloon catheter introduced past the
occlusion, inflated and withdrawn with the clot.
• Good back-bleeding and antegrade bleeding
suggest that the entire clot has been removed.
• Completion angiography to ascertain adequacy.
54. • Advantages:
• Rapid revascularization
• Transfemoral approach can be done via local anesthesia
• Adjunct use intraoperative thrombolysis
• Disadvantages:
• Risk of Vessel injury
• More chances of Reperfusion injury & compartment syndrome.
55. BYPASS PROCEDURES :
Commonly performed in patients :
• After failed open balloon thrombectomy - Last resort!
• Extensive tissue injury.
• Associated Peripheral vascular disease.
56. HYBRID PROCEDURES :
• ALGORITHM :
OPERATIVE
THROMBOEMBOLECTOMY
COMPLETE/NEAR
COMPLETE THROMBUS
EXTRACTION
INCOMPLETE THROMBUS
EXTRACTION WITH SMALL
VOLUME RESIDUAL
THROMBUS
EXTENSIVE RESIDUAL
THROMBUS, MULTIVESSEL
DISTAL OCCLUSION
BOLUS THROMBOLYTIC
AGENT INTO ARTERIAL
SEGEMENT
BOLUS (+REPEAT DOSE
AFTER 30 MINS)
OR
20-30 MIN INFUSION
HIGH DOSE ISOLATED LIMB
PERFUSION
(MANUAL INFUSION OR
WITH PUMP INFUSION
57. INTRA-OPERATIVE THROMBOLYSIS :
Pros:
• Clears residual thrombus in small arteries
and arterioles.
• Minimal risk of bleeding.
Cons:
• Maybe inadequate in some patients with
extensive distal & small vessel thrombosis.
58. AMPUTATION :
Performed as the First (index) procedure in :
• A non-salvageable (Class III limb)
• Low potential of limb salvage
Amputation, Mortality & Long term Limb Salvage for open surgeries in ALI
SERIES YEAR NO. OF PATIENTS AMPUTATION(%) MORTALITY(%) LIMB SALVAGE
Campbell et al 1998 474 16 22 Not Reported
Nypaver et al 1998 71 7 10 62 % at 1 Year
Pemberton et al 1999 107 12 25 75 % at 2 Years
