Pediatric Cardiac Surgery Patients

Boshkov et al. (2003a) reported a retrospective case series in pediatric cardiac surgery patients. HIT antibodies were demonstrated by positive functional assay in five of 433 children following open heart surgery (incidence, 1.2%). Martch-enke and colleagues (2004) found an incidence of HIT with thrombotic complications of 2.5% in pediatric patients after congenital heart surgery. Boning et al. (2005) performed a retrospective analysis to identify the incidences of HIT and of anti-PF4/heparin antibodies in pediatric patients undergoing cardiac surgery. There were 559 cardiac procedures with extracorporeal circulation using heparin in 415 patients with congenital heart defects performed over a 2-yr period. The 144 patients undergoing a scheduled second procedure on extracorporeal circulation were screened preoperatively. Of these 144 patients, 41 underwent a third procedure and were screened before each procedure for the presence of anti-PF4-heparin antibodies and clinical signs of HIT. The incidence of anti-PF4/heparin antibodies was 1.4% (2/144). In none of the patients did clinical HIT occur.

Punzalan and colleagues (2005) performed a prospective study in children receiving heparin during CPB. Of 30 children between 2 days and 50 mo of age, one patient had a borderline positive result and another a positive anti-PF4/ heparin EIA; both tested negative by a functional test (serotonin release assay). Neither patient developed thrombosis.

C. Pediatric Dialysis Patients

Skouri et al. (2006) performed a prospective study in the pediatric hemodialysis unit, evaluating 38 children between 1 and 16 yr of age (mean, 10.45 yr) undergoing chronic hemodialysis thrice weekly. Patients received i.v. UFH as a single bolus (70 IU/kg body weight). Plasma samples were tested for antibodies by PF4/ heparin-EIA and by a functional assay utilizing washed platelets, the heparin-induced platelet activation assay (HIPA). Of 38 patients, nine patients (21%) tested positive by EIA and/or HIPA, but none had thrombocytopenia or clinical thrombosis. Sequential EIAs performed every 3 mo in seven of the eight patients with antibodies detected by EIA showed gradual reductions in antibody levels in six children, with a persistently positive EIA seen in only one patient at 1-yr follow-up.

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