A case of successful withdrawal from cardiopulmonary bypass by correcting plasma Mg²⁺ concentration

A 56-year-old man who had a DeBakey IIIb-type dissecting aortic aneurysm and aortic regurgitation (II°) with old myocardial infarction (ejection fraction = 20%) was scheduled for replacement of the aortic arch and aortic valve with a prosthetic vessel and valve under general anesthesia. After completion of the replacement under cardiopulmonary bypass (CPB), attempts to withdraw the patient from CPB failed twice due to refractory ventricular arrhythmia and hypotension. At the end of the third CPB, plasma Mg ²⁺concentration was corrected by adding 2,000 mg magnesium sulphate (0.30→0.53 mmol/L), and then the patient was successfully withdrawn from CPB. It is important to monitor plasma Mg²⁺ concentration during open-heart surgery, and it would be useful to correct it for refractory ventricular arrhythmia.