VULNERABILITY OF PEDIATRIC MYOCARDIUM TO CARDIAC-SURGERY

Objective - Myocardial injury is an important cause of mortality and m orbidity after paediatric cardiac surgery. Data obtained from studies in animals imply that juvenile myocardium is more resistant to the eff ects of ischaemia and reperfusion than adult myocardium but there is l ittle confirmatory evidence in the clinical setting. Design - Prospect ive observational study of biochemical markers of myocardial injury in a paediatric population undergoing cardiac surgery. Setting - Tertiar y referral centre for paediatric cardiac surgery. Patients - Forty pat ients undergoing paediatric cardiac surgery of varying complexity incl uding closure of atrial and ventricular septal defects and arterial sw itch for simple transposition. A control group included patients under going thoracotomy for closure of a patent ductus arteriosus or repair of a coarctation. interventions-Serial measurements of myoglobin, the MB isoenzyme of creatine kinase (CK-MB), and the highly specific marke rs of myocardial damage cardiac troponin T (cTnT) and I (cTnI) were ma de before and 1, 6, 24, and 48 to 72 hours after operation. Results - There were significant increases in myoglobin and CK-MB, but not cTnT or cTnI, in the control group. There were significant increases in the four biochemical markers in all the cardiac operations but especially in the ventricular septal defect and transposition group. Increases i n CK-MB and cTnT were about five times greater than those previously r eported in adult patients. Conclusions - (i) Cardiac troponins are mor e specific markers of myocardial injury in paediatric cardiac surgery than myoglobin and CK-MB. (ii) Paediatric myocardium seems to be more vulnerable to injury during cardiac surgery than adult myocardium.