Venous Thromboembolism

 

Clinical Background

Deep venous thrombosis (DVT) is the presence of thrombus in a vein with accompanying inflammation.

Epidemiology

  • Incidence
    • 1/1,000 for venous thromboembolic disease (VTE)
    • Estimated 5,000,000 DVT patients annually
    • 500,000 pulmonary emboli (PE) develop from these DVTs
  • Sex – M>F (minimal)
    • M<F during childbearing years
  • Ethnicity
    • More common in Asians and Pacific Islanders
    • Less common in Hispanics (2 to 4 times lower risk than Caucasians and African Americans)

Risk Factors

  • Surgery – highest risk with orthopedic operations
  • Neoplasms – highest risk with pancreas, ovary, lung, urinary tract, breast and stomach cancers
    • Odds ratio of 7.0
  • Trauma – highest risk with fractures of the spine and lower extremities
  • Pregnancy – highest risk in 1st and 3rd trimesters
  • Hormone use – postmenopausal replacement, oral contraceptives, tamoxifen citrate
    • Odds ratio of 2.0-4.0
  • Immobilization – highest risk with acute myocardial infarction (MI), congestive heart failure (CHF) and stroke
  • Hypercoagulable states – anti-phospholipid antibodies, activated protein C resistance/factor V Leiden mutation, prothrombin G20210A mutation, deficiencies of protein C, protein S, or antithrombin, elevated homocysteine
  • Previous DVT or PE
    • Odds ratio as high as 15.6
  • Indwelling catheters – most common source of upper-extremity DVT
  • Age – risk increases incrementally with age

Pathophysiology

  • Factors that predispose to DVT were first described by Virchow in 1856
    • Virchow triad – stasis, vascular damage and hypercoagulability
    • Individual risk is the complex interaction of acquired risk factors and congenital (inherited) factors

Clinical Presentation

  • DVT
    • Extremity pain and swelling, warmth and erythema, pain in the calf with foot dorsiflexion (Homans sign)
      • Usually unilateral
    • Pulmonary embolism
      • Dyspnea, pleuritic chest pain, hemoptysis, low-grade fever, tachycardia, split S2 heart sound on cardiac auscultation

Treatment

  • Therapy is necessary for proximal DVT
  • Acute therapy:
    • Low molecular weight heparin or unfractionated heparin
      • Fondaparinux in certain cases
      • More aggressive therapy is recommended for patients with large PE/DVT
      • Monitor therapy with partial thromboplastin time (PTT) (unfractionated heparin) and heparin anti-Xa test (low molecular weight heparin)
      • Outpatient therapy typically includes oral warfarin (length of treatment depends on clinical factors)
      • Monitor with International Normalized Ratio (INR) to ensure therapeutic range
  • Prophylaxis
    • Depending on risk factors and risk of bleeding, consider use of anticoagulants, graduated compression stockings, or intermittent pneumatic compression