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Postoperative arrhythmias and myocardial electrolytes in patients undergoing coronary artery bypass grafting
B M Jensen1, P Alstrup, N A Klitgård
1Department of Cardiovascular Surgery, Odense University Hospital, Denmark.
Insights
Patients undergoing coronary artery bypass grafting (CABG) with postoperative arrhythmias had lower skeletal muscle potassium and higher right atrial sodium. Electrolyte imbalances may contribute to these arrhythmias, suggesting potential benefits from potassium and magnesium supplementation.
Area of Science:
- Cardiology
- Electrophysiology
- Biochemistry
Background:
- Postoperative atrial fibrillation or flutter is a common complication after coronary artery bypass grafting (CABG).
- Electrolyte disturbances are implicated in the pathophysiology of cardiac arrhythmias.
Purpose of the Study:
- To evaluate electrolyte changes in right atrial and skeletal muscle in patients undergoing CABG.
- To determine the relationship between these electrolyte changes and the development of postoperative atrial fibrillation or flutter.
Main Methods:
- Prospective evaluation of 31 patients undergoing CABG.
- Measurement of electrolyte concentrations (potassium, sodium, magnesium) in right atrial and skeletal muscle tissue, and serum, preoperatively, intraoperatively, and postoperatively.
- Comparison of electrolyte levels between patients who developed and those who did not develop postoperative arrhythmias.
Main Results:
- Postoperative arrhythmias occurred in 45% of patients.
- Patients with arrhythmias had lower preoperative skeletal muscle potassium and higher right atrial sodium concentrations.
- Potassium levels decreased intraoperatively and remained low in skeletal muscle postoperatively; sodium levels increased.
- Serum magnesium declined postoperatively, while tissue magnesium showed no significant changes.
Conclusions:
- Preoperative and intraoperative electrolyte derangements, particularly low skeletal muscle potassium and high right atrial sodium, are associated with an increased risk of postoperative atrial arrhythmias after CABG.
- These electrolyte imbalances suggest impaired transmembrane ion transfer.
- Postoperative potassium and magnesium supplementation may be beneficial in preventing or managing these arrhythmias.
Abstract:
Electrolyte changes in right atrial and skeletal muscle pre- intra- and postoperatively, and their relationship to the development of postoperative atrial fibrillation or flutter were evaluated in 31 patients with coronary artery bypass grafting (CABG). Such postoperative arrhythmias occurred in 14 patients (45%). Before CABG the skeletal muscle potassium concentration was lower in these patients than in the others: median 261.4 (range 148.2-329.5) vs 298.6 (167.1-416.4) mumol/g dry weight, p = 0.017. The right atrial potassium concentration was normal, but sodium levels were higher in the patients with, than in those without postoperative arrhythmias: median 340.3 (263.7-454.9) vs 296.3 (203.9-355.0) mumol/g dry weight, p = 0.008, indicating disturbed transmembrane electrolyte transfer. During CABG the potassium levels fell and sodium increased in both right atrium and skeletal muscle, and on postoperative day 2 the potassium content in skeletal muscle was not yet restored. Magnesium levels showed no changes in right atrium or skeletal muscle, but serum magnesium declined postoperatively. As the observed electrolyte derangements may be important in the development of postoperative arrhythmias, concomitant potassium and magnesium supplement postoperatively may be beneficial in restoring cellular potassium concentration.