Description

• Development of blood clot within the deep veins, usually accompanied by inflammation of the vessel wall.
• Major clinical consequences are embolization (usually to the lung) and postphlebitic syndrome.
• System(s) affected: Cardiovascular

Epidemiology

• Age and gender adjusted incidence of venous thromboembolism (VTE) is 100× higher in the hospital than in the community.
• Of patients with VTE, 1/3 die within 30 days, 20% will have sudden death due to pulmonary embolism (PE). The 28-day DVT fatality rate is 9%.

• In the US, VTE occurs for the first time in 100/100,000/year.
• ∼2/3 of the new VTE cases are deep vein thrombophlebitis (DVT) alone.
• Higher incidence among Caucasians and African Americans relative to Hispanics and Asians
• Complicates ∼1/1,000 pregnancies

• 22–52% of the patients with PE have DVT.
• 25% of patients with superficial venous thrombosis (1)
• Present in 11% of patients with acquired brain injury entering to neurorehabilitation

Risk Factors

• Acquired: Age, previous thrombosis, immobilization, major surgery, orthopedic surgery, malignancy, oral contraceptives, hormonal replacement therapy, antiphospholipid syndrome, polycythemia vera, paroxysmal nocturnal hemoglobinuria, prolonged travel, pregnancy/puerperium
• Inherited: Antithrombin deficiency, protein C deficiency, protein S deficiency, factor V Leiden R506Q, prothrombin G20210A, dysfibrinogenemia
• Mixed/Unknown: Hyperhomocysteinemia, high levels of factor VIII, activated protein C resistance not factor V Leiden, high levels of factor IX, high levels of thrombin activatable fibrinolysis inhibitor (TAFI), high levels of factor XI

• Factor V Leiden is found in 5% of the population and in 20% of all VTE events. It is the most common thrombophilia. Homozygosity is found in 1/5,000 persons. It increases the risk of VTE 3–8-fold in heterozygous carriers and 50–80-fold in homozygous.
• Prothrombin (PT) 20210A is found in 3% of Caucasians. Increases the risk of thrombosis about 3-fold.

General Prevention

• Mechanical thromboprophylaxis is recommended in patients with high bleeding risk and as an adjunct to anticoagulant-based thromboprophylaxis. Mechanical measures include early ambulation, graduated compression stockings, venous foot pump, and intermittent pneumatic compression.
• For acutely ill and for critically ill hospitalized patients at increased risk of thrombosis; low-molecular-weight heparin [LMWH], low-dose unfractionate heparin [LDUH], or fondaparinux are recommended (2).
• For surgical patients, the use of a prediction score for VTE is strongly recommended. If the risk is moderate or higher, LMWH is preferred.
• For most patients, prolonged prophylaxis is not recommended.

Etiology

Factors involved may include venous stasis, endothelial injury and abnormalities of coagulation.