Definition formation of a blood clot in one

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

Anatomy

Etiology and risk factors 3 main factors contribute in development of DVT Stasis Endothelial injury Hypercoagulability

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

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 n n all stages of pregnancy the first three months postpartum, after elective abortion, and during treatment with oral contraceptive pills

Inherited disorders of coagulation Ø deficiencies of protein ‘S’, Ø protein ‘C’ and Ø antithrombin III.

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.

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

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!!

Phlegmasia cerulea dolens Venous gangrene

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

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)

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 Ddimer n n n ELISA latex agglutination blood agglutination test - Simpli. RED

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

Imaging Studies Invasive Ø venography, Ø radiolabeled fibrinogen Noninvasive Ø ultrasound, Ø plethysmography, Ø MRI techniques

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 >95% Able to detect other pathology like BAKER cyst.

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.

Venogram shows DVT

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

clinical limitations reader dependent Duplex scans are less likely to detect nonoccluding 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

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

Color duplex scan of DVT

The only disadvantage of duplex study is that, it is highly operator dependant!!!

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.

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.

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

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

Management The aim of management is: Prophylaxis against DVT Treatment of ongoing DVT

Methods of Prophylaxis: 1) Mechanical Leg elevation Graded compression stocking Early ambulation Pneumatic compression boo.

2) Pharmacological agents: Aspirin (anti platelet factor) not recommended currently. Dextran solution (40 and 70) branched polysaccharide. Decrease platelets adhesiveness and aggregation. Disadvantages: ü Increase rate of bleeding ü Pulmonary edema (due to overload) ü Allergic reaction in 1% Recommended dose is 15 -20 cc/h IV infusion before surgery.

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

Warfarine nomograph

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 q 12 hours post operative till the patient is completely ambulating. For morbidly obese patient: - micro-heparin drip at 1 u/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

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.

Heparin nomograph

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.

An approach to Prophylaxis 1. determine patient at risk Low risk (<40 years old, ambulating, minor surgery) Moderate risk (>40 years old, abdominal, pelvic or thoracic surgery) High risk (>60 years old, prior DVT or PE malignancy, orthopedic surgery hypercoagulability state).

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.

Treatment of DVT A: - anticoagulation Heparin bolus 100 -150 u/kg IV stat then followed by constant infusion of 1000 u/hour with checking a. PTT q 4 -6 hours and keeping the ratio 50 -70 sec. Coumadine (Warfarine) usually started at day 3 -5 after initial heparin is given and continue for 3 -6 months. PT should be 17 -20 sec. and INR 2. 0 -2. 5.

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)

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.

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.

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

Thrombolytic therapy is also not effective once 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.

Catheter directed-thrombolysis Consider in: Acute< 10 days iliofemoral DVT. Long-term benefit in preventing post -phlebitic syndrome is unknown.

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

Filters for DVT Controversial indications: Deep vein thrombosis with contraindication to anticoagulation Deep vein thrombosis in patients with preexisting pulmonary hypertension Free floating thrombus in proximal vein Failure of existing filter device Post pulmonary embolectomy

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.

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.

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

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

Prognosis: All patients with proximal vein DVT are at longterm 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