4 DefinitionsA blood clot that forms in a blood vessel or within the heart and remains there is called a thrombus. A thrombus that travels from the blood vessel or heart to another location in the body is called an embolus, and the disorder, an embolism. For example, an embolus that occurs in the lungs is called a pulmonary embolism.Sometimes, a piece of atherosclerotic plaque, small pieces of tumor, fat clumps, air, amniotic fluid, or other materials can act in the same manner as an embolus. (MEDLINE PLUS)
5 Pathogenesis -Thrombosis Normally - balance between clotting and bleedingWith thrombosis - imbalance with procoagulant state manifestingRisk increases when > 1 risk factor presentVenous thrombi – fibrin & RBCs mainly, leucocytes & plts also presentVirchow’s triad 1) vessel wall damage2) blood flow (stasis)3) hypercoaguability ofbloodVenous thrombosis can affect any part of venous system but deep veins most commonly affected.
13 VTEThrombosis commonly occurs in deep veins of limbs. Can also affect superficial veinsVenous system leg – 2 important categories deep calf vein involvement only proximal vein thrombosis (involving popliteal, femoral or iliac veins) – give rise to clinically significant PEPulmonary emboli ( majority arise from deep veins of leg >90%)Other sources of PE include – upper extremity thrombosis, deep pelvic veins, renal veins, IVC
17 Differential Diagnosis DVT CellulitisPopliteal cystLymphatic obstructionMuscle strain/tearDirect twisting injury to legIf think about DVT – MUST objectively exclude
18 Pulmonary Embolism – Clinical Features Symptoms variableTransient Dyspnoea, tachypnoeaTachycardiaPleuritic chest pain, cough, haemoptysis,CVS collapse with hypotension, syncope ( massive pulmonary embolism)Clinically silentClinical features are non specificONCE again must objectively exclude
19 Laboratory investigations D-Dimer assayCompression ultrasound(DVT)Venography (DVT)Spiral CT (highly sensitive for PEMRIWork up for thrombophilic state when confirm diagnosis
21 Clinical courseUntreated proximal vein thrombosis – potentially lethal – fatal PEExtension of thrombus proximallyPost thrombotic syndrome frequent complication of deep DVT. Heaviness, swelling cramps, itching, ulcerationChronic thromboembolic pulmonary hypertension.
22 Treatment – Anticoagulant Therapy Heparin: Unfractionated or Low Molecular Weight Heparins e.g Enoxaprin(Clexane), Dalteprin,FondaparinuxVitamin K antagonists e.g WarfarinOral anti Xa (clinical trials)Direct thrombin inhibitors
23 Initiation of treatment Must cover with Clexane when initiating Rx with Warfarin – Why? ( short T1/2, Protein C) – relative prothrombotic state
24 Treatment – how long? Individualise each case Look at risk factors presentTransient vs permanent vs no risk factors1st episode vs recurrent thrombosisReassessD-Dimer levelsRisk –Benefit ratio of anticoagulant therapy
25 Treatment – how long ?First onset ,transient risk factor – 6 months , recheck D-Dimer levels . If raised continue ? Indefinite therapy.First onset, idiopathic thrombosis – consider life long Warfarin. Reassess risk-benefit ratioRecurrent DVT – indefinite anticoagulationPatients with APL antibodies or 2 more inherited risk factors – 12 months anticoagulation and reassess
26 Treatment how longFirst episode thombosis – with deficiency of natural anticoagulants e.g. antithrombin, Prot C, Prot S or FVLeiden/Prothrombin gene mutation – 12 months and reassess ? indefinite therapy
27 Side effects of anticoagulant therapy BleedingHeparin Induced thrombocytopenia and thrombosisHeparin induced osteoporosis, increased transaminase levels, hypersensitivity reactions e.g. necrosis, alopecia, hyperkalaemia
28 Treatment – Thrombolytic therapy – When? Indicated in patients with PE – haemodynamically unstable , evidence of R ventricular failureThreatened limb in setting of DVT
29 Prophylaxis – venous thrombosis Important to identify those patient at increased risk of thrombosisPreventionUse of LMWH, compression stockingsAwareness – patients and health care professionals
30 CONCLUSIONVenous thromboembolism – major cause of morbidity and mortalityIdentify risk factors early -institute prophylaxisProphylaxis imperative measure to decrease incidence of thrombotic eventsIf suspect thrombosis must objectively testDuration of treatment – varies -individualise