Deep Vein Thrombosis (DVT)

• DVT is Deep Vein Thrombosis

Virchow's Triad

• Three broad categories of factors that contribute to thrombosis include endothelial damage, hypercoagulability, and stasis

Endothelial Damage

• Smoking and hypertension can cause endothelial dysfunction
• Surgery, catheter insertion (PICC lines), and trauma can also lead to endothelial damage

Hypercoagulability

• Hereditary factors include Factor V Leiden, Prothrombin G20210A, and deficiencies in Protein C and S
• Acquired factors include cancer, chemotherapy, oral contraceptives (OCP)/hormone replacement therapy (HRT), pregnancy, obesity, and heparin-induced thrombocytopenia (HIT)

Stasis

• Immobility and polycythemia contribute to stasis, which can cause endothelial injury

Other Risk Factors

• Additional risk factors for DVT include smoking, obesity, lower extremity trauma, family or personal history of DVT, and age greater than 60 years

Clinical Presentation and Physical Exam

• Clinical presentation includes leg edema in the affected limb and calf tenderness
• Homan's sign (pain when dorsiflexion of the foot) may be present, but it's unreliable and only positive in 33% of cases
• Erythema and pain are also symptoms
• 50% of DVT cases may not present with any symptoms

Differential Diagnoses

• Superficial phlebitis, cellulitis, ruptured Baker's cyst, strained muscle, and malignant neoplasm (compromising vein) should be considered

Well's Score

• A modified Wells Criteria score is used for clinical evaluation to predict the probability of DVT
• The clinical characteristics and corresponding scores are:
• Active cancer (+1)
• Paralysis, paresis, or recent plaster immobilization of the lower extremities (+1)
• Recently bedridden for three days or major surgery within the last 12 weeks (+1)
• Localized tenderness along the deep venous system (+1)
• Entire leg swollen (+1)
• Calf swelling ≥ 3 cm larger than asymptomatic side (+1)
• Pitting edema confined to symptomatic leg (+1)
• Collateral superficial veins (+1)
• Previously documented DVT (+1)
• Alternative diagnosis at least as likely as a DVT (-2)
• A total score of >2 indicates that DVT is likely, where as a score <2 indicates DVT is unlikely
• If a score is greater than 2, a diagnostic study must be ordered

Diagnostic Tests

• Duplex venous ultrasound has 97% sensitivity for proximal DVTs but cannot detect distal DVTs
• D-Dimer: small fibrin fragments that are produced and released into the blood when fibrin blood clots are broken down by plasmin
  • Not specific to DVT but this test will not help with post surgical patients
  • Can be false positive in infection, inflammation, pregnancy, trauma, and surgery
  • Less sensitive with distal DVT's Venography/MRI: can detect iliac vein thrombosis

Management

• Deep vein thrombosis (DVT) may be treated as an outpatient by prescribing Coumadin and Pradaxa/Savaysa for at least 5 days of parenteral injections
• Outpatient treatment is suitable only if the patient has calf DVT, is clinically stable, and has low risk of bleeding
• In cases of limb ischemia, PE symptoms, significant comorbidities (ESRD), functional limitations, high bleeding risk, or non-adherence, the patient should be sent to the ER for inpatient management

Low Molecular Weight Heparin

• Enoxaparin (1 mg/kg BID or 1.5 mg/kg OD) BID for at least 5 days
• Fragmin (100 units/kg BID or 200 units OD)

LMWH + Vitamin K Antagonist

• Coumadin at 5-10 mg OD for 2 days then adjusted; 2-3 INR for 24 hours

LMWH +

• Abigatran (Pradaxa) 150 BID or Edoxaban (Savaysa)
• For patients weighing >60 kg: 60 mg once daily
• For patients weighing ≤60 kg: 30 mg once daily

Another Management Option

• Factor Xa Inhibitor: do not require parenteral anti-coagulation
• Eliquis: 10 mg BID for 7 days followed by 5mg BID
• Xarelto: 15 mg BID for 21 days followed by 20 mg OD

Inpatient Management

• Unfractionated heparin is preferred in patients at high risk, such as those with massive DVT (iliofemoral), severe renal insufficiency, PE symptoms, high bleeding risk, hemodynamic instability, comorbid conditions, or morbid obesity
• Heparin IV administration in the hospital setting involves an 80 units per kg intravenous bolus, followed by a maintenance infusion of 18 units/kg/hr of intravenous continuous infusion, further adjustment per nomogram
• Transition to Coumadin requires an INR between 2-3 for over 24 hours
• Initiate Eliquis, Pradaxa, or Xarelto within 2 hours after discontinuation of heparin infusion

Bleeding Risk

• Major bleeding risk assessment based on risk factors for patients taking anticoagulants:
• Age > 65 years
• Age > 75 years
• Alcohol abuse
• Anemia
• Antiplatelet therapy
• Cancer
• Comorbidity and reduced functional capacity
• Diabetes mellitus
• Frequent falls
• Liver failure
• Metastatic cancer
• Poor anticoagulant control
• Previous bleeding problems
• Previous stroke
• Recent surgery
• Renal failure
• Thrombocytopenia
• The initial risk (0 to 3 months) and risk beyond 3 months are categorized as low, moderate, or high based on the number of risk factors

Management of Distal DVT

• Thrombophlebitis:
• Patients with distal DVTs have a lower risk of embolization, approximately half that of proximal DVTs
• Distal DVTs can resolve spontaneously without therapy
• If symptomatic, treatment is needed due to low risk of bleeding
• About 1/3 of distal DVTs will develop into proximal veins
• "Surveillance with serial ultrasound" may be indicated for low-risk patients (minor thrombus, no history, -D-Dimer, non-diagnostic US or high risk for bleeding patients)
• Survey patients every week for 2 weeks to assess for extension to the proximal veins
• If extension does not occur in 2 weeks, it is unlikely to occur

When to Stop Anticoagulation Therapy

• Reversible Risk Factor (Trauma/Surgery): Stop after 3 months
• Recurrent DVT or Clotting factor: Indefinite period (Hematologist referral)
• Oncology Patients: After at least 3-6 months, or while receiving active chemo, and who also have an active cancer diagnosis
• IVC (inferior vena cava) filter = absolute contraindication to therapeutic anticoagulation, complications from anticoagulation, or failure of anticoagulation in a patient with acute proximal DVT