Letter to the editor

Orgaran (Org 10172) for cardiopulmonary bypass in heparin-induced thrombocytopenia: Role of adjunctive plasmapheresis

One hundred and twenty-two case reports of treatment outcomes of danaparoid use for intermittent haemodialysis (HD) in severely ill patients with heparin intolerance (including 97 HIT patients) have been analysed. HD sessions of 4 – 6 hours were successfully conducted daily to 3 times/week for periods of up to 4 years (median 7 sessions/patient (range 1 - > 650). In these patients danaparoid use was relatively safe (4 unprovoked non-fatal major bleeds) and efficacious in protecting the circuit (95% no clotting problem) or patient (6 thromboses: 4 fatal or leading to danaparoid discontinuation).

HIT diagnosis was improved if recurrent platelet count reduction with each HD and circuit/AV graft clotting were included. Alternative reasons for and very low nadirs of the platelet count undermined the usefulness of the 4T pre-test HIT predictability scores, but a positive functional serological test confirmed HIT in most patients.

Deaths (15.6%) and thrombosis only occurred in HIT cases. Possible reasons are discussed. Replacing the standard intermittent pre-HD dose regimen with the therapeutic infusion regimen to provide continuous daily systemic antithrombotic protection, should further improve efficacy.

Danaparoid appears to be a useful alternative antithrombotic for patients with heparin intolerance and renal failure requiring haemodialysis.

Background. The use of cardiopulmonary bypass (CPB) in patients with a history of type II heparin-induced thrombocytopenia (HIT) may be associated with complications related to their anticoagulation management.

Methods. Between January 1997 and December 1999, among 4,850 adults patients who underwent cardiac surgery in our institution, 10 patients presented with preoperative type II HIT. In 4 patients, anticoagulation during CPB was achieved with danaparoid sodium. In 6 other patients, heparin sodium was used after pretreatment with epoprostenol sodium.

Results. No significant change in platelet count occurred in any patient. No intraoperative thrombotic complication was encountered. Total postoperative chest drainage ranged from 250 to 1,100 ml in patients pretreated with epoprostenol and 1,700 to 2,470 ml in patients who received danaparoid sodium during CPB (p < 0.05, Mann-Whitney U test).

Conclusions. During CPB, inhibition of platelet aggregation by prostacyclin may be a safe anticoagulation approach in patients with type II HIT.

Heparin-induced thrombocytopenia and thrombosis (HITT) is an immunomediated disorder induced by the administration of heparin for therapeutic purposes. The presence of this condition in patients requiring full heparinization for cardiopulmonary bypass constitutes a formidable challenge for the cardiac surgeon. In this review, the clinical and experimental experience described in the literature are discussed in the perspective of the normal coagulation and the pathophysiology of HITT and in the light of a variety of old and new alternative anticoagulants.