Clinical Management of Thrombosis and Thrombotic Disorders CBL PDF

**Clinical Management of Thrombosis and Thrombotic Disorders CBL ** - Define the main locations of venous thrombosis. - Venous thromboembolism (VTE) refers to a blood clot in a vein. - VTE is separated from arterial thrombosis due to differences in pathophysiology, risk fact...

**Clinical Management of Thrombosis and Thrombotic Disorders CBL ** - Define the main locations of venous thrombosis. - Venous thromboembolism (VTE) refers to a blood clot in a vein. - VTE is separated from arterial thrombosis due to differences in pathophysiology, risk factors, and management. - **Deep vein thrombosis** (DVT) is a blood clot in a deep vein of the body, usually in the legs. - **Superficial vein thrombosis** (SVT) is a blood clot in a superficial vein. - **Pulmonary embolism** (PE) is a blood clot in the pulmonary artery or arteries. - **Chronic thromboembolic pulmonary hypertension** (CTEPH) is a rare complication of PEs, resulting in high pressure in the pulmonary vasculature and can cause long-term right-sided heart failure - Compare and contrast differences in management between proximal and distal deep vein thrombosis. - DVTs are divided into proximal and distal veins. - **Proximal vein DVTs** are more likely to embolize (break off) and cause a PE. - **Isolated distal DVTs** are usually treated differently, even if unprovoked. - **Isolated, unprovoked distal DVT: ** - Typically treated with 3 months of anticoagulation, with no long-term anticoagulation needed. - **Unprovoked proximal DVT: ** - Treated like an unprovoked PE, with most patients requiring long-term anticoagulation to prevent recurrent VTE after the acute treatment phase - Compare and contrast imaging modalities for diagnosing venous thrombosis by site of thrombosis. - **Lower Extremity (LE) DVT Diagnosis**:  - Confirmed with imaging, with the standard being a venous doppler ultrasound. - **Pulmonary Embolism (PE) Diagnosis:**  - Requires imaging to confirm.  - CT pulmonary angiogram (CTPA), sometimes called \"CT PE,\" involves a CT scan with intravenous contrast timed to look at the pulmonary vasculature.  - A \"CT chest with IV contrast\" is not the same as a CTPA. - A chest x-ray is not diagnostic for a PE, as a normal chest x-ray can be seen in 12-22 percent of patients with PE.  - Ventilation/perfusion (V/Q) scans can be used instead of CTPA when trying to avoid radiation exposure (e.g., pregnancy).  - However, V/Q scans have higher rates of false negative results than CTAs.  - If a V/Q scan is negative, but the pretest probability for a PE is high, a CTA should still be considered.  - V/Q scans cannot be used if the patient has baseline lung disease.  - Subsegmental PEs are harder to diagnose on imaging due to their small size - Define the role of d dimer in diagnostic evaluation of venous thrombosis - A **D-dimer** is a blood test used in the diagnosis of a PE. - In patients with a low pre-test probability of a PE, a negative D-dimer (i.e., within the normal range) can be used to rule out a PE. In other words, if the pre-test probability of a PE is low and the D-dimer is negative, no additional imaging is required. - If the pre-test probability for a PE is high, the patient should be scanned, and a D-dimer cannot be used to rule out a PE - Define the acute management of venous thrombosis compared to longer term risk reduction of recurrent thrombosis. - **Acute Management:** - Initial treatment may be in the hospital on IV anticoagulation, depending on the severity of the presentation and bleeding risk. - Therapeutic anticoagulation is required for 3 months for provoked DVT/PE, and for 3-6 months for unprovoked DVT/PE. - An IVC filter may be used in the acute management of a patient with a proximal lower extremity DVT who cannot be on anticoagulation due to a high bleeding risk, to block the transit of a large embolus to the lungs. - Ideally, patients with an IVC filter will start anticoagulation at a later date and/or have the IVC filter removed. Long-term, IVC filters increase the risk of thrombosis (clots can form at the site of the filter). - Isolated distal DVTs are usually not an indication for an IVC filter. - For patients who cannot be on anticoagulation due to high bleeding risks, isolated distal DVTs can be managed with serial ultrasounds to monitor progression of the DVT.  - **Longer-Term Risk Reduction** of Recurrent Thrombosis: - Most patients with an unprovoked VTE (or VTE with persistent provoking risk factors) and a low bleeding risk should remain on long-term anticoagulation for \"secondary prevention\" of a recurrent VTE. - After acute treatment of a VTE, the decision on how long to treat with anticoagulation depends on the risk of recurrent VTE if not on anticoagulation, the risk of major bleeding, and the patient\'s preference. - A baseline doppler after finishing acute treatment of the DVT is helpful for comparison if there are new symptoms. New symptoms could be from a new DVT, but could also be from post-thrombotic syndrome. - Compare and contrast provoked versus unprovoked venous thrombosis including definitions and differences in clinical management. - **Provoked VTE occurs with known risk factors, while unprovoked VTE occurs without known risk factors.** - Provoked VTE risk factors → surgery (\>30 min), confined to bed for at least 3 days with acute illness, C section), leg injury (reduced mobility)  - Delineating provoked vs. unprovoked VTE has major impacts on long-term management. - **Provoked VTE** is typically treated with therapeutic anticoagulation for 3 months. - **Unprovoked VTE** is typically treated with therapeutic anticoagulation for 3-6 months, but most patients with an unprovoked VTE and low bleeding risk should remain on long-term anticoagulation for secondary prevention of a recurrent VTE  - Describe acquired risk factors for thrombosis. - Acquired risk factors for thrombosis include older age (65+ years), hormone-related factors (male sex, testosterone use, estrogen use such as with combined oral contraception, depot progestin injection, pregnancy, systemic hormone replacement therapy), obesity, active cancer, inflammatory bowel disease, nephrotic syndrome, surgery, trauma, immobility, central venous catheter, heart failure, and liver failure. - **Antiphospholipid antibody syndrome** is an acquired, autoimmune disease that increases the risk of both venous and arterial thrombosis - Autoantibodies (lupus anticoagulant) target phospholipid-protein complexes, leading to: - Enhanced platelet activation. - Endothelial dysfunction. - Inhibition of anticoagulant pathways. - Activation of the coagulation cascade. - Describe the common inherited thrombophilia disorders and identify limitations of testing for these disorders. - **Factor V Leiden mutation: ** - Mutation in factor V that makes it resistant to activated protein C (binds thrombomodulin), which is part of the \"breaks\" on clotting.  - It is the most common inherited thrombophilia in the Caucasian population.  - Single copy (heterozygous) only mildly increases risk of VTE, while homozygous is rare and causes a marked increase in VTE risk.  - Testing can be done via functional coagulation test (\"activated protein C resistance\") or genetic testing. - **Prothrombin G20210A mutation: ** - A \"gain-of-function\" mutation that causes increased prothrombin activity.  - It is the second most common thrombophilia after Factor V Leiden.  - VTE risk is higher in homozygotes compared to heterozygotes.  - Testing is only genetic. - **Protein S deficiency, Protein C deficiency, and Antithrombin deficiency ** - can be inherited or acquired.  - Testing for these includes quantitative testing and/or a functional coagulation test.  - Antithrombin deficiency can cause resistance to heparin products. - Limitations of testing: - **Most people who have had a VTE do not have an inherited thrombophilia.** - Testing is more likely to be helpful in younger patients with VTE, patients with recurrent VTE, or patients with an extensive family history of VTE. - Negative thrombophilia testing does not exclude the possibility of an inherited thrombophilia. - Do not test for a thrombophilia if it will not change management, which is the case for most patients, as most patients with an unprovoked VTE need long-term anticoagulation regardless of testing results. There are false positive and false negative results if you test when a patient is on anticoagulation or in the acute setting, such as during the initial treatment of a VTE or during another acute event such as an infection