Heparin-induced thrombocytopenia with a focus on children undergoing cardiac surgery

Unfractionated heparin is the anticoagulant of choice for cardiac surgery as it can be easily monitored and antagonized. However, besides bleeding, heparin can induce the adverse effect of immune-mediated heparin-induced thrombocytopenia (HIT). In contrast to adults, for pediatric patients, only few data concerning HIT are available. However, these data indicate that children following cardiac surgery are the pediatric population with the highest risk for HIT. Analyzing 83 children with HIT, a decrease in platelet counts is the most frequent manifestation of HIT occurring in about 79% of patients. HIT was associated with thromboembolic complications in 69% of patients. Eight of 37 children developing HIT after cardiac surgery died, leading to a mortality of up to 21% in this patient population. For laboratory confirmation of clinically suspected HIT, antigen assays are most appropriate due to the small sample volume needed and high negative predictive value. For children, experience with the alternative anticoagulants danaparoid, lepirudin, and argatroban is limited to case reports. However, safe and effective anticoagulation, even for cardiopulmonary bypass surgery, has been reported with these drugs. Use of low molecular weight heparin instead of unfractionated heparin for postoperative anticoagulation may reduce the risk of HIT following cardiac surgery.