Magnesium supplementation in the prevention of arrhythmias in pediatric patients undergoing surgery for congenital heart defects.
BACKGROUND
The efficacy of magnesium in the prevention of arrhythmias in pediatric patients after heart surgery remains unknown. Therefore we prospectively examined the effect of magnesium treatment on the incidence of postoperative arrhythmias in pediatric patients undergoing surgical repair of congenital heart defects.


RESULTS
Twenty-eight pediatric patients undergoing heart surgery with cardiopulmonary bypass were prospectively, randomly assigned in a double-blind fashion to receive intravenous magnesium (magnesium group, n = 13; 30 mg/kg) or saline (placebo group, n = 15) immediately after cessation of cardiopulmonary bypass. Magnesium, potassium, and calcium levels were measured at defined intervals during surgery and 24 hours after surgery. Continuous electrocardiographic documentation by Holter monitor was performed for 24 hours after surgery. Magnesium levels were significantly decreased below the normal reference range for patients in the placebo group compared with the magnesium group on arrival in the intensive care unit and for 20 hours after surgery. Magnesium levels remained in the normal range for patients in the magnesium group after magnesium supplementation. In 4 patients in the placebo group (27%), junctional ectopic tachycardia developed within the initial 20 hours in the intensive care unit. No junctional ectopic tachycardia was observed in the magnesium group (P =.026).


CONCLUSIONS
Although this study was originally targeted to include 100 patients, the protocol was terminated because of the unacceptable incidence of hemodynamically significant junctional ectopic tachycardia that was present in the placebo group. Thus low magnesium levels in pediatric patients undergoing heart surgery are associated with an increased incidence of junctional ectopic tachycardia in the immediate postoperative period.
Dorman
B H
BH
Department of Anesthesia and Perioperative Medicine, Medical University of South Carolina, South Carolina, USA. dormanhb@musc.edu
Sade
R M
RM
Burnette
J S
JS
Wiles
H B
HB
Pinosky
M L
ML
Reeves
S T
ST
Bond
B R
BR
Spinale
F G
FG
D001145:Arrhythmias, Cardiac / Q000097:blood / Q000175:diagnosis / Q000517:prevention & control*; D002118:Calcium / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D002675:Child, Preschool; D004070:Digitalis / Q000627:therapeutic use; D004311:Double-Blind Method; D015716:Electrocardiography, Ambulatory / Q000187:drug effects; D005260:Female; D006330:Heart Defects, Congenital / Q000188:drug therapy / Q000601:surgery*; D006801:Humans; D007262:Infusions, Intravenous; D008274:Magnesium / Q000008:administration & dosage* / Q000097:blood; D008275:Magnesium Deficiency / Q000097:blood / Q000175:diagnosis / Q000517:prevention & control; D008297:Male; D008517:Phytotherapy; D010946:Plants, Medicinal; D010947:Plants, Toxic; D011183:Postoperative Complications / Q000097:blood / Q000517:prevention & control*; D011188:Potassium / Q000097:blood; D011446:Prospective Studies; D013613:Tachycardia, Ectopic Junctional / Q000097:blood / Q000209:etiology / Q000517:prevention & control; D016896:Treatment Outcome
D008274:Magnesium; D011188:Potassium; D002118:Calcium