A clinical study to evaluate the role of intraoperative magnesium sulphate for prophylaxis against arrhythmias in patients undergoing elective open heart surgery

Hypomagnesemia seems to be a frequent finding in patients subjected to cardiac surgery under cardiopulmonary bypass (CPB) due to multifactorial etiology. Hypomagnesemia may be one of the many contributory factors that predispose towards the development of postoperative arrhythmias. Prophylactic magnesium administration in the perioperative period may be beneficial in the control of supraventricular tachyarrhythmias and ventricular ectopics after cardiac surgery. Hence we evaluated the role of intraoperative magnesium sulfate for prophylaxis against arrhythmias in patients undergoing elective open heart surgery under cardiopulmonary bypass.

Methods: Forty adult patients of either sex scheduled for elective cardiac surgery under cardiopulmonary bypass were included in the study. Patients were randomly allocated to two groups of 20 patients each. Group I (study group): 16 mmol L^-1 of magnesium sulfate was added to each litre of cardioplegic solution. Group II (control group): cardioplegic solution without magnesium sulfate was used.

Results: Serum magnesium levels were measured preoperatively, immediately after surgery and 24 hours after surgery. Incidence of hypomagnesmia and arrhythmias were recorded pre and post operatively.

Conclusion: Addition of magnesium sulfate in a dose of 16 mmol L^-1 to cardioplegic solution is safe although it does not prevent the fall in serum Mg ²⁺ levels following CPB. The relative risk for both ventricular and supraventricular arrhythmias is reduced.

DOI: http://dx.doi.org/10.4038/slja.v19i2.3019  

Sri Lankan Journal of Anaesthesiology Vol.19(2) 2011 pp.61-68