[Changes in serum and urinary magnesium during and after extracorporeal circulation in cardiac surgery in children].

Magnesium plays an essential role in the processes of myocardial contraction and conduction. In cardiovascular surgery, extracorporeal circulation (ECC) in haemodilution results in various electrolyte distrubances, with invariably hypomagnesaemia. A group of 13 children undergoing open heart surgery was compared with a group of 17 children operated upon under the same conditions but with the addition of magnesium to the filling solution for the extracorporeal circulation. Changes in blood and urinary electrolytes during and after ECC were studied. Hypomagnesaemia was seen in both groups after surgery but the provision of magnesium supplements shortened the duration. In addition, blood phosphate levels remained significantly higher in the group receiving magnesium. The significance of these various findings is discussed and a technique for the provision of magnesium supplements is proposed.