Thrombosis Management and Treatment
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Questions and Answers

What is the primary action of heparin in the management of thrombosis?

  • It prevents platelet aggregation.
  • It strengthens fibrin strands in clots.
  • It activates coagulation factors by enhancing antithrombin. (correct)
  • It directly lyses clots.

How is unfractionated heparin (UFH) typically monitored during treatment?

  • Using the activated partial thromboplastin time (aPTT). (correct)
  • By assessing the patient's INR levels.
  • Through the measurement of platelet count.
  • Via anti-Factor Xa levels.

Which of the following conditions may necessitate monitoring anti-Factor Xa levels during LMWH treatment?

  • Patients with a recent stroke.
  • Patients who have just undergone elective surgery.
  • Patients who are pediatric or geriatric. (correct)
  • Patients with stable angina.

Direct Oral Anticoagulants (DOACs) function primarily by targeting which coagulation factors?

<p>Factor Xa and IIa. (B)</p> Signup and view all the answers

What is the main advantage of low molecular weight heparin (LMWH) over unfractionated heparin (UFH)?

<p>LMWH has a longer duration of action and more predictable pharmacokinetics. (C)</p> Signup and view all the answers

In which situation is it controversial to treat a diagnosed DVT?

<p>When the DVT is below the knee. (D)</p> Signup and view all the answers

What is the target for aPTT when managing patients on UFH?

<p>2-2.5 times normal aPTT. (C)</p> Signup and view all the answers

What is one of the reasons DOACs are not used during the acute phase of venous thrombosis treatment?

<p>They have unpredictable anticoagulation effects. (D)</p> Signup and view all the answers

What is the primary condition associated with thrombocytopenia in patients receiving heparin?

<p>Heparin-induced thrombocytopenia (HIT) (B)</p> Signup and view all the answers

What should be the target International Normalized Ratio (INR) for patients with venous thrombosis on warfarin?

<p>2.0 to 3.0 (D)</p> Signup and view all the answers

Why is regular monitoring of the INR crucial during warfarin therapy?

<p>To avoid a prothrombotic state (A)</p> Signup and view all the answers

How long is the duration of anticoagulation therapy typically recommended for a patient with venous thrombosis after knee surgery without other risk factors?

<p>3-6 months (D)</p> Signup and view all the answers

What adverse effect is associated with the early phase of warfarin therapy due to the short half-life of protein C?

<p>Increased thrombotic risk (D)</p> Signup and view all the answers

In the context of HIT, how often must platelet counts be checked for patients receiving heparin?

<p>Weekly (A)</p> Signup and view all the answers

What is a prerequisite for ongoing anticoagulation therapy when D-dimer levels remain elevated?

<p>Assessment of bleeding risk (C)</p> Signup and view all the answers

What is the key factor influencing the need for platelet count checks in long-term heparin users?

<p>Duration of heparin use (A)</p> Signup and view all the answers

What is the recommended dose of Rivaroxaban for the prevention of stroke in patients with non-valvular atrial fibrillation and eGFR > 50 mL/min?

<p>20 mg OD (C)</p> Signup and view all the answers

Which of the following patients can receive Rivaroxaban for continued prevention of recurrent DVT and PE?

<p>Patients requiring extended therapy beyond 6 months (C)</p> Signup and view all the answers

What dose adjustment is recommended for patients with an eGFR between 30 and 49 mL/min when taking Rivaroxaban?

<p>Reducing the dose to 15 mg OD (D)</p> Signup and view all the answers

Which classification of patients is explicitly excluded from using Rivaroxaban for stroke prevention?

<p>Patients with rheumatic heart disease (C)</p> Signup and view all the answers

What is the primary major side effect associated with anticoagulant therapy?

<p>Bleeding (D)</p> Signup and view all the answers

What is the initial treatment for acute DVT and PE before starting Rivaroxaban?

<p>Clexane 1 mg/kg bd subcutaneously for three weeks (C)</p> Signup and view all the answers

Which of these statements regarding Rivaroxaban dosing is accurate for patients requiring extended therapy?

<p>20 mg OD is usually prescribed after a period. (C)</p> Signup and view all the answers

What is the stance on the use of fibrinolytic agents like streptokinase for DVTs?

<p>They are not supported for routine use. (A)</p> Signup and view all the answers

Flashcards

DVT Treatment (small thrombi)

Treatment for deep vein thrombosis (DVT) below the knee is often observation by monitoring for extension; no immediate treatment might be needed.

DVT Treatment (major thrombi)

Treatment for major DVTs above the knee always involves anticoagulation with heparin (UFH or LMWH) or a DOAC.

Heparin (UFH)

An anticoagulant that enhances antithrombin's action on coagulation factors Xa and IIa, delaying clot extension.

Heparin (LMWH)

A heparin type that also enhances antithrombin's action, primarily on factor Xa, and does not require as much frequent monitoring..

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DOAC (Direct Oral Anticoagulant)

Anticoagulants that directly affect coagulation factors IIa or Xa, used for acute and ongoing DVT therapy.

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Anticoagulation Monitoring (UFH)

The activated partial thromboplastin time (aPTT) is used to monitor the activity of UFH.

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Anticoagulation Monitoring (LMWH)

Anti-Factor Xa levels can monitor LMWH but it's typically not mandatory, due to predictable activity.

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Anticoagulation mechanism

Anticoagulants don't break down clots themselves, but prevent their growth, allowing the body to dissolve clots naturally.

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Rivaroxaban Dosage (Atrial Fibrillation)

20 mg daily for life in patients with an eGFR over 50 mL/min for stroke and systemic embolism prevention in non-valvular atrial fibrillation.

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Rivaroxaban Dosage (DVT/PE - Initial)

15 mg twice daily or initial Clexane (1 mg/kg twice daily), then 20 mg daily for at least 3 months for DVT/PE treatment, with eGFR > 50mL/min.

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Rivaroxaban Dosage (DVT/PE - Extended Prevention)

20 mg daily, or 10 mg daily in select cases, for extended treatment of DVT/PE beyond 6 months.

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eGFR Monitoring for Rivaroxaban

eGFR (estimated Glomerular Filtration Rate) levels influence rivaroxaban dosage and use, with reduced dosages for eGFR between 30-49 mL/min, with consideration for anti-Xa monitoring, whilst eGFR < 30 mL/min excludes rivaroxaban use.

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Rivaroxaban Side Effect

Bleeding is a major side effect of rivaroxaban and is controlled by monitoring anticoagulant levels due to the risk of increased bleeding with over-anticoagulation.

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Heparin-Induced Thrombocytopenia

A side effect of heparin therapy that shows reduction in platelets.

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Fibrinolytic Agents (DVT/PE Treatment)

Not routinely used for DVT except in cases of venous gangrene for the treatment of DVT/PE due to insufficient evidence for routine use.

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Patient Exclusion Criteria (Rivaroxaban)

Patients with rheumatic heart disease or mechanical heart valves are excluded from rivaroxaban use for stroke/systemic embolism prevention.

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HIT

An autoimmune disease where the body's immune system attacks platelets, causing them to drop, which can lead to paradoxical thrombosis (clotting) despite being on heparin.

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How to Monitor for HIT

Regular platelet counts (at least weekly) are vital for patients on heparin to detect a significant drop in platelet count, which is a hallmark of HIT.

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Warfarin Mechanism

Warfarin inhibits vitamin K epoxide reductase, leading to a relative vitamin K deficiency. This reduces the production of several clotting factors (II, VII, IX, X) and anticoagulant proteins (C & S), initially causing a prothrombotic state.

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Why is Warfarin Prothrombotic Initially?

Since protein C has the shortest half-life, it's depleted first by warfarin, creating a temporary prothrombotic state. This is especially risky for patients with protein C deficiency, who are more prone to clotting.

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INR

International Normalized Ratio (INR) is a standardized measure of blood clotting time, used to monitor warfarin therapy. It should be maintained between 2 and 3 for patients with venous thrombosis.

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Warfarin Therapy Duration

The length of warfarin treatment depends on the underlying risk factors. For a temporary event like knee surgery, it's 3–6 months. But for a spontaneous clot or strong family history, it can be extended to 9 months or longer.

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D-Dimer

A protein fragment found in the blood after a clot breaks down. Elevated D-dimer levels can indicate ongoing clotting activity, necessitating continued anticoagulation.

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VTE Prophylaxis

Preventive measures (pharmacologic and non-pharmacologic) for Venous Thromboembolism (VTE), aiming to reduce the risk of deep vein thrombosis (DVT) and pulmonary embolism (PE) in high-risk situations like major surgery.

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Study Notes

Thrombosis Management

  • Aim: To study the management and prophylaxis of thrombosis.
  • Objective: Describe the principles involved in the management and prophylaxis of thrombosis.

Treatment of Thrombosis

  • Diagnosis & Small Thrombi: Once a deep vein thrombosis (DVT) is diagnosed, anticoagulation begins. Treatment of small thrombi below the knee is debated; some experts suggest no initial treatment but rather monitoring (e.g., repeat Doppler exams) for extension before treatment. Major thromboses above the knee require treatment.
  • Initial Treatment: Treatment options include heparin (unfractionated (UFH) or low molecular weight heparin (LMWH)), or Direct Oral Anticoagulants (DOACs) like rivaroxaban.
    • Heparin: Enhances antithrombin's action on coagulation factors, inhibiting clot extension. Heparin doesn't directly dissolve clots, but allows the body's fibrinolytic system to work effectively.
      • UFH: Has a 2-hour action, given intravenously or subcutaneously, and aPTT (activated partial thromboplastin time) is used to monitor its activity, aiming for a 2-2.5x increase in aPTT compared to normal. aPTT monitoring must happen within 2 hours of drawing the sample.
      • LMWH: Has a 12-hour action, mainly targets factor Xa, given subcutaneously. Anti-Factor Xa levels monitor its activity, although it is often not mandatory.
    • DOACs: Act directly on factors Flla or Xa, with controlled action and don't require routine monitoring, suitable for acute and ongoing therapy. Rivaroxaban is a common example.

DOAC Indications and Dosage

  • Indications:
    • Prevention of stroke and systemic embolism (non-valvular atrial fibrillation)
    • Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE)
  • Continued Prevention: Prophylactic treatment of recurrent DVT and PE
  • Dosage (Rivaroxaban):
    • eGFR > 50 mL/min: 20 mg once daily, lifelong.
    • eGFR 30-49 mL/min: 15 mg twice daily or dosage reduction or anti-Xa monitoring.
    • eGFR < 30 mL/min: Rivaroxaban not typical.
    • Lower dosages may be necessary. Consult specific guidelines for renal impairment .

Additional Considerations

  • Fibrinolytic Agents: While agents like streptokinase can dissolve clots, data doesn't typically support routine use for DVTs except in severe cases (e.g., venous gangrene).
  • Heparin-induced Thrombocytopenia (HIT): A side effect of heparin. Platelet levels can drop after treatment and thrombosis may occur.
  • Warfarin: A vitamin K antagonist. Initial warfarin use often occurs alongside heparin for DVT treatment, and INR monitoring (2-3) is crucial. Treatment duration depends on risk factors or cause and can range from 3-9 months.
  • Prophylactic Measures: Venous thromboembolism (VTE) prophylaxis involves pharmacologic and nonpharmacologic measures (e.g., during orthopedic surgery). Guidelines are available (Jacobson, Louw, Buller, et al - 2013).

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Related Documents

LT.05 Management of Thrombosis (Including Prophylaxis) PDF

Description

This quiz explores the management and prophylaxis of thrombosis, focusing on treatment options for deep vein thrombosis (DVT) and small thrombi. Key concepts include the use of anticoagulants like heparin and Direct Oral Anticoagulants (DOACs), as well as the principles guiding their application. Test your knowledge on managing various thrombotic conditions.

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