We investigated the efficacy, safety and relation of dose to plasma anti-Xa activity of the low molecular weight heparin (LMWH) dalteparin in prophylaxis and therapy of arterial and venous thrombosis in pediatric patients. A total of 48 children were enrolled: 10 received dalteparin for prophylaxis (group I), 8 for reocclusion prophylaxis following successful thrombolysis (group II), 5 following failed thrombolysis (group III) and 23 for primary antithrombotic therapy (group IV). Two children were treated with dalteparin for pulmonary veno-occlusive disease (PVOD) and for primary pulmonary hypertension (PPH), respectively.
Outcome: In group I no thrombo-embolic event occurred. In group II recanalization was maintained or improved, in group III vascular occlusion persisted under dalteparin. In group IV we saw complete recanalization in 7/23 (30%), partial recanalization in 7/23 (30%) and no recanalization in 9/23 (40%) cases. The child with PVOD had recanalization proven by lung biopsy; the clinical condition of the child with PPH also improved. Minor bleeding occurred in 2/48 (4%) children. For prophylaxis 95 +/- 52 (mean and SD) anti-Xa IU/kg BW, for therapy 129 +/- 43 (mean and SD) anti-Xa IU/kg BW proved effective. For both prophylaxis and therapy the required dose per kg BW was inversely related with age (r2 = 0.64, P = 0.017; r2 = 0.13, P = 0.013).
Conclusion: Dalteparin proved to be an effective and well tolerated drug for prophylaxis and therapy of thrombosis in pediatric patients. Dose requirement for effective treatment was higher in younger children and decreased with age.