Heparin - induced thrombocytopenia type 2 after nadroparin administration in patient after primary total knee arthroplasty - a case report
Abstract
Heparin-induced thrombocytopenia type II (HIT II) is a rare complication of unfractionated heparin (UFH) and low molecular weight heparin (LMWH) therapy. Antibodies against a complex of heparin with platelet factor 4 (HIT-Ig) are the main factors in ethiopathogenesis of HIT II.
HIT-Ig are subsequently binded to platelet receptors FcgRIIa, this leads to platelet activation which is associated with the induction of procoagulant activity through increased production of thrombin. HIT II is thus combination of thrombocytopenia and procoagulant state with risk of both venous and arterial thrombosis.
HIT II manifests itself most often between the 4th and 14th day after initiation of heparin therapy, it occurs about 0.1 to 1% in case of LMWH, higher incidence (1-3%) has been described in case of UFH. In therapy HIT is necessary immediately discontinuation of heparin therapy, then alternative anticoagulants are administrated - eg. a direct thrombin inhibitors (bivalirudin, argatroban), indirect Factor Xa inhibitors (fondaparinux, danaparoid), while use of Warfarin and new oral anticoagulants (rivaroxaban, dabigatran) are not recommended for HIT in acute phase.
This case report describes a patient after total knee arthroplasty of the right knee joint, with whom nadroparin was administered as thromboprophylaxis (prior to surgery 0.6 ml s.c. once a day, then gradually was increase up to 1.0 ml s.c. twice a day during third postoperative day. (PAI-1 polymorphism, patient was after previous deep venous thrombosis of left lower limb and pulmonary embolism, according duplex ultrasonography stationary post-thrombotic changes were recognized). The fifth post-op day platelet count start decreasing, the decrease lasted even blood sample 7th day postoperatively.
According haematologist recommendation, extended test of coagulation and panel of pathologic platelet count was added, which proved HIT-Ig and HIT II. Nadroparin was stopped and immediately replaced by fondaparinux, following duplex sonography was without evidence of acute venous thrombosis, echocardiography without impairment of right and left ventricle kinetics.
The platelet count was rapidly increased, after stabilization the patient was subsequently converted to Warfarin, he was demitted after 32 days in good overall health state.