Role of magnesium in the prevention of postoperative arrhythmias in neonates and infants undergoing arterial switch operation

The objectives of the study were to measure magnesium levels in neonates and infants undergoing arterial switch operation and to ascertain the role of magnesium supplementation in the prevention of postoperative arrhythmias. Group I (n=25): magnesium was administered in the dose of 30 mg/kg over 10 minutes in normal saline (5 ml) immediately after cessation of cardiopulmonary bypass (CPB). Group II (n=25): normal saline (5 ml) was administered over 10 minutes immediately after cessation of CPB. Samples of arterial blood were collected at four time points: 1) after induction of anaesthesia; 2) 10 minutes after initiation of CPB; 3) at rewarming during CPB; and 4) 4 hours after shifting the patient to the intensive care unit. Samples were measured for ionized magnesium (iMg), blood gases, haematocrit level, electrolytes, ionized calcium and glucose. Continuous ECG rhythm analysis and documentation of arrhythmias was performed for 24 hours after surgery. The mean preoperative iMg levels were below the normal level in both the groups. A significant increase in iMg levels (P=0.00) was seen in both groups during rewarming. There is no statistically significant difference in the incidence of arrhythmias between the magnesium supplemented group (4%) and the control group (20%) in the postoperative period, a tendency towards reduction in arrhythmias was only observed in the magnesium supplemented group.