Deep Vein Thrombosis
Thrombophlebitis:
Condition in which a blood clot forms and blocks one or more veins.
Superficial thrombophlebitis: Blockage near the skin surface.
Deep venous thrombosis (DVT): Thrombosis located in a muscle
Occur in deep veins leading to the vena cava
Typically found in the legs, especially calves (most hospitable environment).
Deep veins in arms, chest, neck are not typical locations for thrombus formation.
Approximately 50% of DVTs are asymptomatic.
Symptoms depend on clot location and size.
Pathophysiology
Thrombi:
Arterial thrombi: Occur at sites of arterial plaque rupture.
Venous thrombi: Occur when there's low blood flow within normal vein conditions.
DVT
Virchow triad: Three pathological factors associated with thrombus formation.
Circulatory stasis: Stagnation of blood flow contributes to clot formation.
Vascular damage: Damage to veins stimulates the clotting cascade.
Hypercoagulability: Increased tendency of blood to clot.
Vascular damage stimulates the clotting cascade, leading to thrombus propagation in the direction of blood flow, triggering an inflammatory response.
Thrombus behavior:
Thrombus may float within a vein.
Pieces may break loose, traveling as emboli through the circulation.
Fibroblasts invade the thrombus, scar the vein, and can destroy venous valves.
Damage may be permanent, affecting normal blood flow even if valve patency is restored.
Risk Factors
Thrombi
Commonly a complication of hospitalization, surgery, immobilization.
Other predisposing factors include:
Venous injury.
Cancer.
Pregnancy.
Use of oral contraceptives or hormone replacement therapy (HRT).
Clotting disorders.
Obesity.
Personal and family history of venous thromboembolism.
DVT
Orthopedic procedures.
Atrial fibrillation.
Acute myocardial infarction.
Ischemic stroke.
DVT Prevention
Maintaining a healthy weight.
Regular walking to encourage circulation.
Staying hydrated to reduce the risk of clotting.
Refraining from immobility: stand up and walk around every hour.
Avoiding leg crossing while sitting.
Avoiding smoking and excessive alcohol consumption.
Prophylaxis:
Low-molecular-weight heparins (LMWH).
Oral anticoagulation.
Elevating foot of bed while keeping knees slightly flexed.
Early mobilization following procedures or during illness.
Leg exercises and use of elastic stockings or pneumatic compression devices.
Manifestations
Leg pain: 90%
Tenderness: 85%
Ankle edema: 76%
Calf swelling: 42%
Dilated veins: 33%
Homan's sign (sharp pain in the calf on dorsiflexion of the foot): 33%
Often asymptomatic or symptoms may vary in severity.
Typical symptoms include aching pain in the affected extremity especially when walking.
Possible tenderness, warmth, erythema, cyanosis, and edema.
Rarely, a palpable cord may be felt along the affected vein.
Diagnosis
Wells Score
Wells score ≥ 2 points = DVT likely
Wells score ≤ 1 point = DVT unlikely
For suspected DVT:
Determine the 2-level DVT Wells score.
If suspecting DVT, a vein ultrasound scan should be done within 4 hours or a D-dimer test if not previously performed.
If DVT is confirmed with ultrasound, therapeutic anticoagulation is started.
If D-dimer is positive but DVT is unlikely, appropriate follow-up is initiated with repeat scanning.
Wells Score Criteria:
Active cancer (treatment ongoing, within 6 months, or palliative): 1 point.
Paralysis, paresis, or recent plaster immobilization of lower extremities: 1 point.
Recently bedridden for 3 days or more, or major surgery within 12 weeks requiring general or regional anesthesia: 1 point.
Localized tenderness along the distribution of the deep venous system: 1 point.
Entire leg swollen: 1 point.
Calf swelling > 3 cm compared to the asymptomatic leg: 1 point.
Pitting edema confined to the symptomatic leg: 1 point.
Collateral superficial veins (non-varicose): 1 point.
Previously documented DVT: 1 point.
An alternative diagnosis is at least as likely as DVT: -2 points.
Laboratory Studies:
D-dimer test.
Prothrombin time (PT).
Partial thromboplastin time (PTT).
Activated partial thromboplastin time (aPTT).
Bleeding time.
Platelet count.
Imaging Tests:
Duplex venous ultrasonography.
Plethysmography.
MRI.
Ascending contrast venography.
Treatment
Pharmacologic Therapy
Thrombolytic drugs are used to accelerate clot lysis, particularly in patients with serious complications and low risk of bleeding.
NSAIDs to reduce inflammation in veins and provide symptom relief, especially in patients with superficial venous thrombosis.
Anticoagulants:
Heparin:
Dosage is calculated to maintain aPTT at twice the control or normal value.
Usually administered as a continuous infusion or subcutaneously as an alternative.
Warfarin:
Used in combination with IV heparin for 4–5 days until INR is stabilized.
Takes up to 5 days for full effects.
Dosages adjusted to maintain INR > 2.0.
Regular follow-up and maintenance dose to prevent recurrent thrombosis.
Continue therapy for at least 3 months.
LMWH:
More effective with a lower risk of bleeding and do not require close laboratory monitoring.
Administered subcutaneously in fixed doses.
Direct thrombin inhibitors:
Inactivate free and bound thrombin; limited use in specific cases.
Factor Xa inhibitors:
Disrupt coagulation cascade directly, useful in treating and preventing DVT, and protecting against stroke in patients with atrial fibrillation.
Competitive with warfarin and have advantages, including fewer dietary interactions and avoidance of frequent INR monitoring.
Consider risks of serious ischemic events when discontinuing without alternatives.
Surgical
Venous thrombectomy:
Performed when thrombus lodges in the femoral vein to prevent PE or gangrene.
Duration of effect can vary between patients.
Filters:
Placed for recurrent thrombosis when anticoagulation is contraindicated.
Vein ligation:
Aims to prevent clot extension into the deep venous system.
Nonpharmacologic
Application of warm, moist compresses on the affected area.
Resting the extremity and elevation above heart level.
Use of anti-inflammatory agents.
Bed rest advised, with legs elevated above the heart.
Initiate walking when permitted, avoiding tight clothing or stockings.
Complications
Recurrence of DVT
Pulmonary embolism (PE; clot or fragments travel to pulmonary circulation)
Lifespan Considerations
Infants and Children:
DVT is rare but risk factors include prematurity and infection.
Symptoms often nonspecific and may involve acute pain and swelling.
Treatment with unfractionated heparin or LMWH is common, transitioning to oral warfarin when appropriate.
Adolescents and Young Adults:
Increased risk especially in females using hormonal contraceptives.
Symptoms include swelling, pain, and warmth; diagnosis and treatment are similar to adults.
Precaution against teratogenic effects of anticoagulant drugs, as they can affect pregnancy outcomes.
Pregnant Women:
Higher risks during pregnancy and the postpartum period.
Preferred use of heparin; monitoring for complications and progress is crucial.
Transitioning to warfarin postpartum poses risks that require careful monitoring.
Older Adults:
Increased risk of DVT and comorbidities complicate management.
Often asymptomatic or exhibit nonspecific signs.
Assessments must consider age-related factors affecting test results and treatment outcomes.