High‐dose methylprednisolone and endothelial glycocalyx in paediatric heart surgery

Background Corticosteroids are used in paediatric heart surgery to attenuate systemic inflammatory response. Glycocalyx regulates vascular permeability, shear stress and cell adhesion on the endothelium. Syndecan-1 serves as a biomarker of glycocalyx degradation. Hydrocortisone decreased endothelial glycocalyx degradation in an experimental model. Our hypothesis was that high-dose methylprednisolone decreases glycocalyx degradation as measured by plasma sydecan-1 concentration in children undergoing cardiac surgery. Methods Two double-blinded, randomized, placebo-controlled trials were conducted. In the first trial (‘neonatal trial’), 40 neonates undergoing open heart surgery received either 30 mg/kg intravenous methylprednisolone (n = 20) or placebo (n = 20). In the second trial (‘VSD trial’), 45 infants and very young children, undergoing ventricular or atrioventricular septal defect correction received one of the following: 30 mg/kg of methylprednisolone intravenously after anaesthesia induction (n = 15), 30 mg/kg methylprednisolone in the cardiopulmonary bypass prime solution (n = 15) or placebo (n = 15). Plasma syndecan-1 concentrations were measured. Results were expressed both as absolute concentrations and in relative concentrations as multiples of the baseline values of syndecan-1. Results There were no statistically significant differences between the neonate trial groups for absolute syndecan-1 concentrations. However, operative administration of methylprednisolone to neonates significantly reduced the relative increases of syndecan-1 at weaning from cardiopulmonary bypass (P = 0.008) and at 6 h post-operatively (P = 0.018). There were no statistically significant differences in absolute or relative increases of syndecan-1 between the VSD trial study groups. Conclusion High-dose methylprednisolone reduces shedding of glycocalyx in neonates after complex cardiac surgery but not in older infants after repair of VSD/AVSD with shorter ischaemia times.