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Myocardial cations and trace metals in cardioplegia: a clinical study
Insights
Myocardial magnesium depletion during cold cardioplegia can be prevented by increasing magnesium concentration in the infusate. This study investigated cation and trace metal changes during cardiac surgery for improved myocardial protection strategies.
Area of Science:
- Cardiology
- Biochemistry
- Physiology
Background:
- Cations and trace metals are crucial in myocardial pathophysiology.
- Understanding their dynamics during cardioplegia is key for refining myocardial protection techniques.
Purpose of the Study:
- To investigate the changes in myocardial, blood, and urine concentrations of calcium, magnesium, zinc, and copper during cold cardioplegia.
- To determine the impact of different magnesium concentrations in cardioplegic solutions on myocardial magnesium levels.
- To assess the effect of calcium-free infusate on myocardial calcium concentration.
Main Methods:
- Serial myocardial, blood, and urine samples were collected from 12 patients undergoing cardiac surgery.
- Atomic absorption spectrometry was used to measure concentrations of calcium, magnesium, zinc, and copper.
- Analysis focused on changes during cold cardioplegia and cardiopulmonary bypass.
Main Results:
- Myocardial magnesium levels significantly decreased with 0.69 mmol/l magnesium in cardioplegic solution but normalized with 2.2 mmol/l.
- Myocardial calcium concentration decreased with calcium-free infusate; zinc and copper levels remained unchanged.
- Serum concentrations of these metals decreased during cardiopulmonary bypass, with normal 24-hour urinary excretion.
Conclusions:
- Optimizing magnesium concentration in cardioplegic solutions is essential to prevent myocardial depletion.
- While cation and trace metal levels fluctuate during cardiac surgery, their clinical significance requires further investigation.
- Findings provide valuable data for designing future cardioplegic solutions with optimal compositions for myocardial protection.
Abstract:
Cations and trace metals play important roles in the pathophysiology of myocardium, and understanding their changes during cardioplegia may be important in further refining the technique of myocardial protection. Serial myocardial, blood and urine samples were taken from 12 patients undergoing cardiac operation under cold cardioplegia. The concentrations of calcium, magnesium, zinc and copper were measured with an atomic absorption spectrometer. Myocardial magnesium levels were found to be significantly (P less than 0.05) depleted when the "cardioplegic" solution contained 0.69 mmol/l of magnesium, but this could be prevented by increasing the magnesium concentration of the infusate to 2.2 mmol/l. With calcium-free infusate, the myocardial calcium concentration decreased, but zinc and copper values did not change significantly. There were decreased serum concentrations of these cations and trace metals during tbe hemodilution cardiopulmonary bypass but their 24-hour excretions in urine were within normal range. Although the clinical importance of such changes remains to be elucidated, the information may be valuable in designing future cardioplegic solutions with optimal compositions.