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Effect of magnesium and calcium on myocardial protection by cardioplegic solutions
N Takemoto1, H Kuroda, T Hamasaki
1Department of Surgery, Tottori University School of Medicine, Yonago, Japan.
Insights
Magnesium and calcium concentrations in cardioplegic solutions significantly impact heart protection during hypothermic arrest. Optimal ionic balance is crucial for preserving cardiac function and aortic flow recovery.
Area of Science:
- Cardiology
- Biochemistry
- Physiology
Background:
- Hyperkalemic cardioplegic solutions are used to protect the heart during surgery.
- The roles of magnesium and calcium in these solutions require further elucidation.
Purpose of the Study:
- To investigate the cardioprotective effects of varying magnesium and calcium concentrations in cardioplegic solutions.
- To determine the optimal ionic balance for myocardial protection during hypothermic ischemic arrest.
Main Methods:
- Isolated rat hearts were subjected to 180 minutes of hypothermic (20°C) ischemic arrest.
- Cardioplegic solutions with varied magnesium (0, 8, 16 mmol/L) and calcium (0.1, 0.6, 1.2 mmol/L) concentrations were administered.
- Recovery of aortic flow, cardiac function, and creatine kinase leakage were assessed.
Main Results:
- Aortic flow recovery was dependent on calcium concentration at each magnesium level.
- Maximum aortic flow recovery reached 70.0% ± 3.5% in the 16 mmol/L Mg, 0.6 mmol/L Ca group.
- No significant differences in cardiac function recovery or enzyme leakage were observed across tested groups.
Conclusions:
- The cardioprotective effect of cardioplegic solutions is influenced by the relative concentrations of magnesium and calcium.
- Maintaining an appropriate ionic balance is essential for effective myocardial protection.
Abstract:
The cardioprotective effect of the magnesium and calcium content of hyperkalemic cardioplegic solutions was investigated using isolated rat hearts subjected to hypothermic ischemic arrest. Hearts were arrested for 180 minutes at 20 degrees C by administering a 3-minute infusion of cardioplegic solution containing various concentrations of magnesium and calcium. Treatment groups received solution with either 0, 8, or 16 mmol/L magnesium. For each of these magnesium concentrations, 0.1, 0.6, or 1.2 mmol/L calcium was also present in the solution. At each concentration of magnesium, the percentage recovery of aortic flow was dependent on the calcium concentration. The maximum percentage recovery of aortic flow was 67.9% +/- 2.3% (mean +/- standard error of the mean) in the Mg-free, 0.1 mmol/L Ca group, whereas it was 65.1% +/- 2.7% in the 8 mmol/L Mg, 0.1 mmol/L Ca group and 70.0% +/- 3.5% in the 16 mmol/L Mg, 0.6 mmol/L Ca group. No significant differences in the recovery of cardiac function and creatine kinase leakage were observed between the three groups. The findings suggested that the cardioprotective effect was dependent on the relative concentration of both magnesium and calcium, and that it is important to maintain an appropriate ionic balance in cardioplegic solutions.