DEEP VENOUS THROMBOSIS

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DEEP VENOUS THROMBOSIS
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Definition

• formation of a blood clot in one of the deep
  veins of the body, usually in the leg

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Anatomy
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Etiology and risk factors

• 3 main factors contribute in development of DVT
• Stasis
• Endothelial injury
• Hypercoagulability

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Venous stasis

• prolonged bed rest (4 days or more)
• a cast on the leg
• limb paralysis from stroke or spinal cord injury
• extended travel in a vehicle
• heart failure

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Hypercoagulability

• Surgery and trauma - responsible for up to 40
  of all thromboembolic disease
• Malignancy
• Increased estrogen (due to a fall in protein S)
  Increased estrogen occurs during
• all stages of pregnancy
• the first three months postpartum,
• after elective abortion, and
• during treatment with oral contraceptive pills

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Inherited disorders of coagulation

• deficiencies of protein S,
• protein C and
• antithrombin III.

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Acquired disorders of coagulation

• nephrotic syndrome results in urinary loss of
  antithrombin III, this diagnosis should be
  considered in children presenting with
  thromboembolic disease
• Antiphospholipid antibodies accelerate
  coagulation and include the lupus anticoagulant
  and anticardiolipin antibodies.

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• Inflammatory processes, such as
• systemic lupus erythematosus (SLE),
• sickle cell disease, and
• inflammatory bowel disease (IBD),
• also predispose to thrombosis, presumably due to
  hypercoagulability

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Symptoms

• Dull pain, heaviness, oedema and warm limb
• With extensive DVT-massive oedema, cyanosis,
  dilated superficial collateral veins and low
  grade fever.
• With ilio-femoral DVT-
• Phlegmasia cerulea dolens (cyanosed limb due to
  obstructed vein)
• Phlegmasia alba dolens (pale, pulseless cold limb
  due to concurrent arterial spasm)
• AND THESE TWO UPPER CASES ARE LIMB THREATENING
  CONDITION!!

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Phlegmasia cerulea dolens Venous
gangrene
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Signs

• HOMAN'S sign (tenderness during passive
  dorsiflexion of foot). And it was contraindicated
  because of its role in thrombus deattachment
  and thus emobilization
• Hotness, cyanosis, oedema (non-pitting)

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Diagnostic Studies

• - Clinical examination alone is able to confirm
  only 20-30 of cases of DVT
• - Blood Tests
• the D-dimer - have predictive value for DVT
• INR - useful for guiding the management of
  patients with known DVT who are on warfarin
  (Coumadin)

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D-dimer

• D-dimer is a specific degradation product of
  cross-linked fibrin. Because concurrent
  production and breakdown of clot characterize
  thrombosis, patients with thromboembolic disease
  have elevated levels of D-dimer
• three major approaches for measuring D-dimer
• ELISA
• latex agglutination
• blood agglutination test - SimpliRED

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• False-positive D-dimers occur in patients with
• recent (within 10 days) surgery or trauma,
• recent myocardial infarction or stroke,
• acute infection,
• disseminated intravascular coagulation,
• pregnancy or recent delivery,
• active collagen vascular disease
• metastatic cancer

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Imaging Studies

• Invasive
• venography,
• radiolabeled fibrinogen
• Noninvasive
• ultrasound,
• plethysmography,
• MRI techniques

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Imaging studies

• The standard tool for diagnosis is
  phlebography using fluoroscope. The use of this
  study limited by is complications which are
  allergy, nephropathy and phlebitis.
• Duplex ultrasound
• Test of choice
• Sensitivity and specificity gt95
• Able to detect other pathology like BAKER cyst.

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Venography

• "gold standard modality for the diagnosis of DVT
  
• Advantages
• venography is also useful if the patient has a
  high clinical probability of thrombosis and a
  negative ultrasound,
• it is also valuable in symptomatic patients with
  a history of prior thrombosis in whom the
  ultrasound is non-diagnostic.

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Venogram shows DVT
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Ultrasonography

• color-flow Duplex scanning is the imaging test of
  choice for patients with suspected DVT
• inexpensive,
• noninvasive,
• widely available
• Ultrasound can also distinguish other causes of
  leg swelling, such as tumor, popliteal cyst,
  abscess, aneurysm, or hematoma.     

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clinical limitations

• reader dependent
• Duplex scans are less likely to detect
  non-occluding thrombi.
• During the second half of pregnancy, ultrasound
  becomes less specific, because the gravid uterus
  compresses the inferior vena cava, thereby
  changing Doppler flow in the lower extremities

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The finding are

• Acute DVT
• Absence of spontaneous flow.
• Loss of flow variation with respiration.
• Failure to increase the flow after distal
  augmentation.
• Not visible thrombi (anechoic thrombi).
• Chronic DVT
• Not well established
• Narrow vein
• Patent collateral
• Visible thrombi

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Color duplex scan of DVT
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• The only disadvantage of duplex study is that, it
  is highly operator dependant!!!

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Magnetic Resonance Imaging

• It detects leg, pelvis, and pulmonary thrombi
  and is 97 sensitive and 95 specific for DVT.
• It distinguishes a mature from an immature clot.
• MRI is safe in all stages of pregnancy.

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Differential diagnoses

• Unilateral limb involvement muscular strain,
  tendon rupture, cellulites, lymphodema or
  retroperitoneal fibrosis pressing over the vein.
• Bilateral limb involvement liver, heart or renal
  failure or IVC obstruction.

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Complication of DVT

• Recurrent DVT
• Varicose vein
• Chronic venous insufficiency
• Post phlebitic syndrome (pain, oedema and
  ulceration)
• PE

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Patient with suspect symptomatic Acute lower
extremity DVT
negative
Venous duplex scan
Low clinical probability
observe
High clinical probability
positive
negative
Evaluate coagulogram /thrombophilia/ malignancy
Repeat scan / Venography
IVC filter
Anticoagulant therapy contraindication
yes
No
pregnancy
LMWH
OPD
LMWH
warfarin
hospitalisation
UFH
Compression treatment
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Management

• The aim of management is
• Prophylaxis against DVT
• Treatment of ongoing DVT

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Methods of Prophylaxis

• 1) Mechanical
• Leg elevation
• Graded compression stocking
• Early ambulation
• Pneumatic compression boo.

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• 2) Pharmacological agents
• Aspirin (anti platelet factor) not recommended
  currently.
• Dextran solution (40 and70) branched
  polysaccharide. Decrease platelets adhesiveness
  and aggregation.
• Disadvantages
• Increase rate of bleeding
• Pulmonary edema (due to overload)
• Allergic reaction in 1
• Recommended dose is15-20 cc/h IV infusion before
  surgery.

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• Warfarine (coumadine)-
• Decrease incidence of DVT by 66 and PE by 80.
• Disadvantages
• Sever hemorrhage
• Must be started 2-3 days preoperative.
• Require careful monitoring for PT.

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Warfarine nomograph
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Heparin

• 
  
  Unfractionated heparin
• Inhibits AT III and potentiate disintegration of
  thrombi that form while it administered
• Low dose regimen is 5000 IU twice daily SQ two
  hours pre-operatively then q12hours post
  operative till the patient is completely
  ambulating.
• For morbidly obese patient - micro-heparin drip
  at 1u/kg/hour
• Disadvantages
• Risk of bleeding
• Thrombocytopenia (rare)
• Contraindicated in patient with actively bleeding
  peptic ulcer, uncontrolled HTN, bleeding disorder
  or recent use of ASA

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• Heparin-dihydroergotamine (DHE) combination
• Cause vasoconstriction of capacitance veins and
  thus increase the venous return.
• Particular effectiveness in orthopedic cases.
• Contraindicated in case of hypotension, IHD and
  peripheral arterial occlusive diseases.
• Low molecular weight (enoxaparin)
• Lesser effect on thrombin and platelets
  aggregation.
• Longer life time so the dose will be once daily.
• More expensive than unfractionated heparin.

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Heparin nomograph
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• Fibrinogen-depleting compound
• New class of anticoagulants but not well known.
• Prophylactic IVC filter placement.
• Also known as Greenfield filter.
• Used in high risk patient when other methods are
  contraindicated.
• Effective in preventing PE not DVT.

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An approach to Prophylaxis

• 1. determine patient at risk
• Low risk (lt40 years old, ambulating, minor
  surgery)
• Moderate risk (gt40 years old, abdominal,
  pelvic or thoracic surgery)
• High risk (gt60years old, prior DVT or PE
  malignancy, orthopedic surgery hypercoagulability
  state).

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• 2. prohylaxis of choice
• Encourage all patients to ambulate as soon as
  possible
• Low risk patient don't need prophylaxis.
• Moderate risk pneumatic compression boot or low
  dose heparin prophylaxis.
• High risk combination of pneumatic compression
  boot and low dose heparin prophylaxis or Dextran.
• Coumadine or IVCfilter are considered.
• Ophthalmology or neurosurgery patient are NOT
  candidates for prophylaxis.

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• Treatment of DVT
• A - anticoagulation
• Heparin bolus 100-150 u/kg IV stat then followed
  by constant infusion of 1000 u/hour with checking
  aPTT q 4-6hours and keeping the ratio 50-70sec.
• Coumadine (Warfarine) usually started at day 3-5
  after initial heparin is given and continue for
  3-6 months . PT should be 17-20sec. and INR
  2.0-2.5.

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Duration of anticoagulation in patients with deep
vein thrombosis

• Transient cause and no other risk factors
  3 months
• Idiopathic 3-6 months
• Ongoing risk for example, malignancy
  6 -12 months
• Recurrent pulmonary embolism or deep vein
  thrombosis 6-12 months
• Patients with high risk of recurrent thrombosis
  exceeding risk of anticoagulation indefinite
  duration (subject to review)

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• B-thrombolytic treatment(
  alteplase, streptokinase, urokinase)
• Promote rapid thrombus lysis. Used in cases of
  sever PE . They have more bleeding complication.
• C-venal cava interruption (IVC filter)
• Prevent further embolism of thrombi
• D- venous thrombectomy
• May be necessary in venous gangrene and septic
  thrombosis.

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Thrombolytic therapy for DVT

• Advantages include
• prompt resolution of symptoms,
• prevention of pulmonary embolism,
• restoration of normal venous circulation,
• preservation of venous valvular function,
• and prevention of postphlebitic syndrome.

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• Thrombolytic therapy does not prevent
• clot propagation,
• rethrombosis, or
• subsequent embolization.
• Heparin therapy and oral anticoagulant
• therapy always must follow a course of
• thrombolysis.

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• Thrombolytic therapy is also not effective once
  the thrombus is adherent and begins to organize
• The hemorrhagic complications of thrombolytic
  therapy are formidable (about 3 times higher),
  including the small but potentially fatal risk of
  intracerebral hemorrhage.

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Catheter directed-thrombolysis

• Consider in Acutelt 10 days iliofemoral DVT.
• Long-term benefit in preventing
  post-phlebitic syndrome is unknown.

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Filters for DVT

• Indications for insertion of an inferior
• vena cava filter
• Pulmonary embolism with contraindication to
  anticoagulation
• Recurrent pulmonary embolism despite adequate
  anticoagulation

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Filters for DVT

• Controversial indications
• Deep vein thrombosis with contraindication to
  anticoagulation
• Deep vein thrombosis in patients with
  pre-existing pulmonary hypertension
• Free floating thrombus in proximal vein
• Failure of existing filter device
• Post pulmonary embolectomy

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Filters for DVT

• Inferior vena cava filters reduce the rate of
  pulmonary embolism but have no effect on the
  other complications of deep vein thrombosis.

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Surgery for DVT

• Indications
• when anticoagulant therapy is ineffective
• unsafe,
• contraindicated.
• The major surgical procedures for DVT are
• clot removal and partial interruption of the
• inferior vena cava to prevent pulmonary
• embolism.

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• These pulmonary emboli removed at autopsy look
  like casts of the deep veins of the leg where
  they originated.

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This patient underwent a thrombectomy. The
thrombus has been laid over the approximate
location in the leg veins where it developed.
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Prognosis

• All patients with proximal vein DVT are at
  long-term risk of developing chronic venous
  insufficiency.
• About 20 of untreated proximal (above the calf)
  DVTs progress to pulmonary emboli, and 10-20 of
  these are fatal. With aggressive anticoagulant
  therapy, the mortality is decreased 5- to
  10-fold.
• DVT confined to the calf virtually never causes
  clinically significant emboli and thus does not
  require anticoagulation

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thank you