Deep Venous Thrombosis (DVT)

• • Virchow's triad: Stasis, vascular injury, hypercoagulability

  • -Stasis: Venous insufficiency, heart failure, prolonged bed rest/plane travel

    -Endothelial injury: Direct trauma, chemotherapy infusion, previous DVT, phlebitis, operative trauma all increase release of tissue factor increasing thrombin and decreasing fibrinolysis

    -Hypercoagulability: Malignancy, protein C or S deficiency, disseminated intravascular coagulation (DIC), liver failure, elevated homocysteine, factor V Leiden, prothrombin gene variant, paroxysmal nocturnal hemoglobinuria

  • Important risk factors

  • -Recent surgery

    -Trauma

    -Cancer

    -Prolonged immobilization

    -Oral contraceptive use

  • Other risks

  • -Advanced age

    -Type A blood group

    -Obesity

    -Prior DVT

    -Multiparity

    -Inflammatory bowel disease

    -Systemic lupus erythematosus

  • Most common in calf veins, may arise in femoral or iliac

  • 25% calf DVT progress proximally

  • Proximal DVT (femoral or iliac)

  • -Chronic venous insufficiency, 25%

    -Fatal pulmonary embolism (PE), 10%

  • Phlegmasia cerulea dolens caused by iliofemoral venous thrombosis, which is characterized by cyanosis of limb from venous outflow obstruction; potentially limb-threatening

  • In phlegmasia alba dolens, leg is pulseless, pale, cool; potentially limb-threatening

Epidemiology

• • Affects 500,000 persons in United States each year

  • Up to 21% mortality in elderly

  • 20-30% of new DVT have occult malignancy (lung, pancreas, prostate, breast, ovary most common)

  • Surgery increases risk 21-fold

  • Complication rates

  • -General surgery, 20%

    -Neurosurgery, 24%

    -Hip/knee arthroplasty, 50%

Symptoms and Signs

• • 50% are asymptomatic

  • Thigh or calf pain with or without edema

  • Extensive DVT

  • -Massive edema

    -Cyanosis

    -Dilated superficial veins

  • Low-grade fever, tachycardia

  • 50% have positive Homans sign (calf pain with ankle dorsiflexion)

  • Acute PE

  • Phlegmasia

Imaging Findings

• • Duplex US

  • -Sensitivity/specificity > 95%

    -Evaluate vein for flow, dilation, and incompressibility (indicate clot present)

    -Acute clot anechogenic, chronic clot echogenic

    -Less accurate to detect calf thrombosis

  • Magnetic resonance venography (MRV)

  • -Sensitivity/specificity nearly 100%

    -Gadolinium MRV for thrombus age

  • D-dimer levels

  • -Too nonspecific

Rule Out

• • Local muscle strain

  • Achilles tendon rupture

  • Cellulitis

  • Lymphedema

  • Baker cyst obstructing popliteal vein

  • Retroperitoneal mass (obstructing iliac vein)

  • Congestive heart failure (CHF), liver, kidney failure, inferior vena cava (IVC) obstruction (bilateral edema)

• • Duplex US

  • Consider hypercoaguable work-up if idiopathic

  • CT scan thorax with pulmonary embolus-specific protocol

• • Goal is to reduce complications

Anticoagulation

• • Primary treatment

  • Decreases recurrence and PE risk by 80%

  • Limits propagation of clot (no effect on clot lysis)

  • Iliofemoral thrombosis

  • -Thrombolytic therapy

    -Surgical thrombectomy

  • IVC filter is contraindication to anticoagulation

Surgery

Indications

• • Calf compartment syndrome

  • Massive extremity edema

Medications

Heparin

• • Potentiates antithrombin III, inhibits thrombin

  • Partial thromboplastin time (PTT) goal of 2 times normal

  • Effective heparinization ...