Overview
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- Diagnosis - provoked or unprovoked PE, preceding DVT
- Management - anticoagulation
- Complications - infarction, right heart failure, pulmonary hypertension
Risk Factors for Pulmonary Embolism
Genetic Predisposition
- Inherited hypercoagulability - protein C or S deficiency, factor V Leiden, prothrombin gene mutation, sickle cell disease, hyperhomocysteinaemia, antithrombin III deficiency
- Family history of VTE
Patient Factors
- Advanced age
- Past history of VTE
- Acquired hypercoagulability - antiphospholipid syndrome, hyperviscosity, PNH, TTP, HITS
- May-Thurner syndrome (anatomical variant where the right common iliac artery overlies and compresses the left common iliac vein)
- Malignancy
- Hormonal therapy - oestrogen-containing oral contraceptives, hormone replacement, SERMs
- Venous pathology - varicose veins, superficial vein thrombosis
Environmental Triggers
- Trauma
- Surgery - particularly hip / knee surgery or major surgery
- Pregnancy / peripartum period
- Continuous immobilisation >72 hours - bedrest, neurologic pathology, cast
- Hospital or nursing home admission
- Long-distance travel (air, land or sea)
Complications
Complications of Pulmonary Embolism
Disease-Related
- Pulmonary infarction
- Right heart failure
- Chronic thromboembolic pulmonary hypertension (CTEPH)
Treatment-Related
- Major bleeding
Management
Management Options
- Thrombolysis (haemodynamically unstable patients)
- Anticoagulation - heparin, low molecular weight heparin, warfarin, dabigatran, rivaroxaban, apixaban
Pearls: Choice of Anticoagulant
- Heparin infusion - short-term, for bridging or in the perioperative period. APTT must be monitored regularly as per local protocol.
- Low molecular weight heparin (e.g. enoxaparin) - first line for patients with active malignancy; also used for bridging. Contraindicated if CrCl <30.
- Warfarin - must be bridged. INR must be monitored. Can be used in renal failure. Inferior to enoxaparin in active malignancy.
- Dabigatran - contraindicated if CrCl <30.
- Rivaroxaban - contraindicated if CrCl <30, severe liver disease, on protease inhibitors / azoles, pregnancy / breastfeeding. Potential role in active malignancy.
- Apixaban - contraindicated if CrCl <25, severe liver disease, on protease inhibitors / azoles, pregnancy / breastfeeding.
Contraindications to Anticoagulation
- Absolute - active bleeding, major trauma, platelets <50, bleeding diathesis, perioperative
- Relative - past incompressible bleed, intracranial or spinal tumour, platelets <100, large AAA, high falls risk
Duration of Anticoagulation
- Provoked VTE (transient risk factors) - 3 months then reassess based on risk of recurrence and bleeding
- First unprovoked VTE - 3 months then continue depending on risk of recurrence and bleeding
- Recurrent unprovoked VTE - long-term anticoagulation
- Thrombophilia - consider long-term anticoagulation
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