Deep Vein Thrombosis and Venous Thrombo Embolism

DVT (Deep vein Thrombosis)

• Factors that increases the risk of deep venous thrombosis as described by Virchow in 1856 include:

1.        Stasis
2.        Hypercoagulability
3.        Endothelial Trauma

• Thrombi below the popliteal fossa usually do not embolize.
• 50% of thrombi at or above the popliteal fossa will embolize
• The risk of thrombosis increased with trauma such as fracture of spine, pelvis, femur and tibia.
• Immobilisation regardless of the cause is a major predisposing factor for DVT.

Risk factors for DVT:

• Age >60 years
• Prolonged immobility or paralysis
• History of DVT or PE
• Family history of DVT or PE
• Cancer
• Obesity
• Varicose veins
• Acute Medical Illness
• Inflammatory Bowel Disease
• Stroke
• Major lower extremity trauma, including fractures of the pelvis and hip
• Hypercoagulable states
• Sepsis
• Hormone therapy
• Inherited thrombophilia
• Smoking
• Pregnancy and post partum period

The risk of DVT is increased by inherited thrombophilia, including the presence of:

• Protein C and S deficiency
• Heparin cofactor II deficiency
• G20210A prothrombin gene polymorphism
• Dysfibrinogenemia
• Factor V Leiden deficiency

Clinical Features

• Unilateral leg swelling, warmth and erythema.
• The most dangerous consequence of DVT is pulmonary embolism
• Homan’s sign: Passive dorsiflexion of the ankle causing pain.
• Mose’s sign: compression of the calf by gentle squeezing elicits pain

Investigations

a)    For DVT

D Dimer Assay:

• The use of D-dimer assay combined with clinical prediction rules has a high negative predictive value. Eg., a normal D Dimer assay and absence of clinical signs excludes the diagnosis of DVT.

Doppler Ultrasonography

• Sensitive for detection of DVT
• Has highest sensitivity for proximal veins, moderate sensitivity for distal veins, but highly specific in both locations
• Operator-dependent

Venography

• 100% sensitive and specific
• Provides visualization of the entire deep venous system
• Still considered as the gold standard, but it is expensive and invasive

MRI is useful in patients with suspected thrombosis of inferior venacava or pelvic veins.

b)    For Pulmonary Embolism:

• ECG: S1Q3T3 pattern
• X-rays: pleural effusion or wedge-shaped pulmonary infarction may be noted.
• Ventilation-perfusion scan:

–        A normal ventilation-perfusion scan excludes PE.

• Pulmonary angiography:

–        100% sensitive and specific, but expensive and invasive.

• Spiral chest CT:

–        Sensitive and specific for PE detection

–        Replaced pulmonary angiography as the new gold standard with modern multidetector row CT scanners

Treatment

Prevention of pulmonary embolism is the main reason for treating DVT.

Venous Thrombo Embolism (VTE) prophylaxis

• Initial therapy includes Low Molecular Weight heparin(LMWH) or low dose unfractionated heparin(LDUH)
• The minimum duration of heparin is 5 days and extended prophylaxis as long as 30 days are recommended when feasible. Cost effectiveness should be considered for extended duration prophylaxis
• Warfarin has been the best oral anticoagulant of choice for many decades. But the narrow therapeutic window, slow onset of action, multiple food and drug interaction, genetic and metabolic variations have paved the way for newer oral anti-coagulants
• Newer oral anticoagulants that target thrombin or factor Xa, like rivaroxaban, dabigatran etexilate, apixaban appear to be promising, and may surpass the use of warfarin
• Fondaparinux: a synthetic pentasaccharide may be used in patients undergoing major orthopaedic surgery.
• Mechanical prophylaxis including graduated compression stockings, intermittent pneumatic compression and foot pumps are very important in preventing venous thromboembolis,
• In patients where anticoagulants are contraindicated, protection from pulmonary embolism can be done by mechanical methods like IVC filter.
• Those who have recurrent thromboembolic phenomenon should be anticoagulated for life

Established DVT:

• Initial therapy includes unfractionated heparin or LMW heparin or fondaparinux. LMWH is preferred.
• VKA (warfarin) can be safely started at the same day and the dose is titrated according to the international normalized ratio (INR) with a target of 2.5 (range 2–3).
• LMWH therapy should be continued for at least 5 days and can be discontinued if the INR is >2 on two consecutive measurements at least 24 h apart
• At the same time the patient should be begun on Warfarin and should be continued for 3- 6 months.
• The minimum duration of heparin in 5 days
• In patients where anticoagulants are contraindicated, protection from pulmonary embolism can be done by mechanical methods like IVC filter.
• Those who have recurrent thromboembolic phenomenon should be anticoagulated for life
• Massive venous thrombosis places the extremity at high risk for ischemia and gangrene and emergency thrombolysis using streptokinase or r-TPA should be performed.

 

Evidence Based Recommendations for DVT prophylaxis:

• For elective spinal surgeries, mechanical prophylaxis is recommended. There is no evidence to suggest that chemoprophylaxis is necessary
• Spinal cord injury patients are associated with a high rate of VTE and LMWH is recommended
• There is no evidence to suggest that chemoprophylaxis is necessary for knee arthroscopy and fractures below the knee
• Mechanical prophylaxis has an important role in prevention of VTE
• Warfarin is less effective than LMWH in preventing VTE
• Aspirin has a good role in preventing VTE, but its use as a single agent is not recommended
• Thromboprophylaxis started 12 hours before surgery has not been shown to be more effective than prophylaxis initiated 12–24 hours after surger

Highlights: Prevention of Venous Thromboembolism in Orthopaedic Surgery. American College of Chest Physicians Evidence-based Clinical Practice Guidelines, Ninth Edition

• In patients undergoing THA or TKA we recommend use of one of the following for a minimum of 10 to 14 days rather than no anti-thrombotic prophylaxis: LMWH, fondaparinux, apixaban, dabigatran, rivaroxaban, LDUH, adjusted-dose VKA, aspirin (all grade 1B), or an Intermittent  Pneumatic Compression Device(IPCD) (grade 1C)
• For patients undergoing major orthopedic surgery (THA, TKA, HFS) and receiving LMWH as thromboprophylaxis, we recommend starting either 12 h or more preoperatively or 12 h or more postoperatively rather than within 4 h or less preoperatively or 4 h or less postoperatively (grade 1B)
• In patients undergoing THA or TKA, irrespective of the concomitant use of an IPCD or length of treatment, we suggest the use of LMWH in preference to the other agents we have recommended as alternatives: fondaparinux, apixaban, dabigatran, rivaroxaban, LDUH (all grade 2B), adjusted-dose VKA, or aspirin (all grade 2C)
• For patients undergoing major orthopedic surgery, we suggest extending thromboprophylaxis in the outpatient period for up to 35 days from the day of surgery rather than for only 10 to 14 days (grade 2B)
• In patients undergoing major orthopedic surgery, we suggest using dual prophylaxis with an antithrombotic agent and an IPCD during the hospital stay (grade 2C)
• In patients undergoing major orthopedic surgery and increased risk of bleeding, we suggest using an IPCD or no prophylaxis rather than pharmacologic treatment (grade 2C)
• In patients undergoing major orthopedic surgery, we suggest against using IVC filter placement for primary prevention over no thromboprophylaxis in patients with an increased bleeding risk or contraindications to both pharmacologic and mechanical thromboprophylaxis (grade 2C)
• For asymptomatic patients following major orthopedic surgery, we recommend against Doppler (or duplex) ultrasound screening before hospital discharge (grade 1B)

Ref:

1. Geerts WH, Bergqvist D, Graham F, et al. Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th edition). Chest 2008;133:318–453S.
2. Spinal Cord Injury Thromboprophylaxis Investigators. Prevention of venous thromboembolism in the rehabilitation phase after spinal cord injury: prophylaxis with low-dose heparin or enoxaparin. J Trauma 2003;54:1111–15.
3. Slobogean GP, Lefaivre KA, Nicolaou S, O’Brien PJ. A systematic review of thromboprophylaxis for pelvic and acetabular fractures. J Orthop Trauma 2009;23:379–384.
4. Abelseth G, Buckley RE, Pineo GR, Hull R, Rose MS. Incidence of deep-vein thrombosis in patients with fractures of the lower extremity distal to the hip. J Orthop Trauma 1996;10:230–5.