Heparin-induced thrombocytopenia in children: 12 new cases and review of the literature

Abstract

Immune-mediated heparin-induced thrombocytopenia (HIT) is a rare but severe adverse effect of heparin therapy. Only few data are available on clinical presentation, diagnosis and management of HIT in children. Records of all patients sent to our laboratory between 1995 and November 2003 were reviewed. To identify literature reports a Medline search was performed, the reference lists of those publications were screened and the abstracts of meetings on thrombosis and hemostasis between 2000 and 2003 were assessed. We identified 12 new HIT patients between 13 months and 18 years of age from our laboratory and 71 reports on HIT in children in the literature. For the assessment of frequency of HIT all studies enrolling > 100 patients were analyzed. HIT is rare in children. In pediatric patients, there seem to be two risk groups: newborns and infants under 4 years of age undergoing cardiac surgery (incidence approximately 1-2%), and teenagers treated with heparin for thrombosis. For confirmation of HIT in children, antigen assays are most important. There are conflicting data on the optimal cut-off, with one randomized, double-blind trial indicating that the cut-off established in adults is appropriate. There are no systematic studies on alternative anticoagulants in children affected by HIT. Most data are available for lepirudin and danaparoid. Substitution of unfractionated heparin by low-molecular-weight heparins for regular anticoagulation may reduce the incidence of HIT.

Bivalirudin anticoagulation for cardiopulmonary bypass in a patient with heparin-induced thrombocytopenia

“…3,6 Current experience with bivalirudin for CPB is based mainly on case-reports of HIT-positive patients who underwent CABG, 15 heart transplantation, 16 left ventricular assist implantation 17 and pediatric heart surgery. 18 There are small studies 6,19 describing bivalirudin use in HIT-negative cardiac surgery patients who underwent elective on or off pump CABG surgery. Some report massive transfusion of blood products and the use of factor VIIa 16 during the early postoperative period.…”

Małopłytkowość poheparynowa

“…HIT in children is rare [16]; it predominantly regards children with increased risk of thromboembolic complications and affects mostly two age groups [84]. The first group involves preterm infants, newborns requiring intensive care and/or vascular catheters and newborns after cardiac surgery procedures (the incidence of HIT is estimated at approximately 1%).…”

Heparin-Induced Thrombocytopenia Screening and Management in Pediatric Patients

“…The reason for these different results is not clear, but may have been due to the different assays used to detect HIT antibodies. In children, the majority of reported cases of pediatric HIT are associated with UFH exposure, 15,16 but at least one case of HIT with LMWH has been described. 17 Lastly, age also may affect the risk of HIT development.…”

“…HIT also appears to be more common in adolescents. 15,16 The reason for the increased risk in these age groups is not clear but may reflect the increased heparin exposure in these populations.…”

“…19 Most thrombotic events reported in pediatric patients appear to be venous rather than arterial; perhaps in part due to a decreased incidence of atherosclerosis in children. 15,16 In adults with HIT, gangrene, skin necrosis, and systemic reactions have all been described; these events have also been rarely reported in children. However, the true frequency of these life-and limb-threatening occurrences in children is not well known.…”