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Effects of calcium in continuous cardioplegia on myocardial protection
N Takemoto1, H Kuroda, Y Nakamura
1Second Department of Surgery, Tottori University Faculty of Medicine, Japan.
Insights
Adding calcium (Ca) to hyperkalemic cardioplegic solutions improved heart protection. Concentrations above 0.6 mmol/l prevented calcium paradox and maintained cardiac function, suggesting optimal cardioprotection.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Biochemistry
Background:
- Cardioplegic solutions are crucial for myocardial protection during cardiac surgery.
- Hyperkalemic solutions are commonly used but can induce calcium paradox.
- Optimizing calcium concentration is vital for effective cardioprotection.
Purpose of the Study:
- To investigate the impact of varying calcium concentrations on hyperkalemic cardioplegic solutions.
- To evaluate the cardioprotective effects and potential for calcium paradox.
- To determine the optimal calcium level for continuous cardioplegia.
Main Methods:
- Isolated perfused working rat heart model.
- Perfusion with Krebs-Henseleit buffer containing 20 mmol/l potassium and varying calcium concentrations (0.1, 0.6, 1.2, 2.5 mmol/l).
- Induction of cardiac arrest at 37°C for 180 minutes, followed by assessment of cardiac function and creatine kinase (CK) leakage.
Main Results:
- Calcium concentrations of 0.6, 1.2, and 2.5 mmol/l showed no significant differences in aortic flow recovery or CK leakage compared to controls.
- The 0.1 mmol/l calcium group exhibited the characteristic calcium paradox.
- No significant differences in cardiac function recovery or CK leakage were observed between higher calcium groups and the control group.
Conclusions:
- Cardioplegic solutions with calcium concentrations exceeding 0.6 mmol/l demonstrate excellent cardioprotective effects.
- Maintaining adequate calcium levels prevents the calcium paradox during continuous cardioplegia.
- These findings support the use of higher calcium concentrations for enhanced myocardial protection.
Abstract:
The effects of calcium (Ca) on a hyperkalemic cardioplegic solution for continuous cardioplegia were examined in an isolated perfused working rat heart model. The coronary arteries were perfused with a modified Krebs-Henseleit bicarbonate buffer (K-H) solution, containing various concentrations of Ca (0.1, 0.6, 1.2, and 2.5 mmol/l) and a high concentration of potassium (20 mmol/l), for 180 min, after which cardiac arrest was induced at 37 degrees C for 180 min. Cardiac function and creatine kinase (CK) were measured. In the control group, K-H solution was infused in place of the cardioplegic solution, and cardiac arrest was not induced. No significant differences were observed between the groups infused with the K-H solution containing Ca concentrations of 0.6, 1.2, and 2.5 mmol/l in the percent recovery of aortic flow (82.1 +/- 2.9%, 80.6 +/- 2.0%, and 71.5 +/- 3.7% (mean +/- SEM) respectively) or in the recovery of other indices of cardiac function, or in CK leakage. There were also no significant differences in the recovery of cardiac function and CK leakage between these groups and the control group. In the Ca 0.1 mmol/l group, however, the characteristic Ca paradox was observed. These findings suggest that if the Ca concentration in a cardioplegic solution is higher than 0.6 mmol/l during continuous cardioplegia, excellent cardioprotective effects will be achieved.