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Electrolyte versus blood cardioplegia: randomized clinical and myocardial ultrastructural study
Insights
Blood cardioplegia better preserves heart muscle during bypass surgery than electrolyte solutions, reducing damage and improving recovery. This finding offers crucial insights for cardiac surgical procedures.
Area of Science:
- Cardiology
- Cardiac Surgery
- Biomedical Engineering
Background:
- Coronary artery bypass surgery requires myocardial protection.
- Cardioplegia solutions are essential for preserving heart function during bypass.
- Optimizing cardioplegia composition is critical for reducing myocardial injury.
Purpose of the Study:
- To compare the efficacy of blood-based versus electrolyte-based cardioplegia.
- To evaluate myocardial preservation and ultrastructural integrity.
- To assess clinical outcomes including left atrial pressure and cardiac enzyme release.
Main Methods:
- Randomized controlled trial in 40 patients undergoing coronary artery bypass.
- Comparison of two cardioplegia solutions: electrolyte (Group A) and blood (Group B).
- Assessment of intramyocardial temperature, left atrial pressure, CPK-MB levels, and myocardial ultrastructure via electron microscopy.
Main Results:
- Blood cardioplegia maintained significantly higher myocardial temperatures (20.3°C vs 16.5°C).
- Lower left atrial pressure (8.1 torr vs 11.9 torr) and reduced CPK-MB elevation (15% vs 45%) in the blood group.
- Electron microscopy revealed less intracellular edema, mitochondrial swelling, and myofibrillary disorganization with blood cardioplegia.
Conclusions:
- Blood-based cardioplegia offers superior myocardial protection compared to the tested electrolyte solution.
- Improved ultrastructural preservation and reduced biochemical markers of injury are associated with blood cardioplegia.
- These findings suggest blood cardioplegia is a valuable alternative for cardiac surgery.
Abstract:
In 40 consecutive patients undergoing coronary artery bypass, one of two solutions for cardioplegia, each containing 30 mEq/L of K+ was used randomly. The groups were comparable except for intramyocardial temperature. With electrolyte solution (Group A), it was 16.5 degrees +/- 0.34 degrees C, while with blood from the pump-oxygenator (Group B) it was 20.3 degrees +/- 0.41 degrees C (p less than 0.001). After bypass left atrial pressure (LAP) was 11.9 +/- 0.67 torr in Group A and 8.1 +/- 0.49 torr in Group B (p less than 0.001). CPK-MB was elevated in 45% of Group A patients versus 15% in Group B (p less than 0.05). No patient died. Two myocardial infarctions occurred in Group A and one in Group B. Stereological morphometric electron microscopy was performed on biopsy specimens taken from the left ventricle (1) before perfusion, (2) after cardioplegia, and (3) 30 minutes after reperfusion. Group A showed marked intracellular edema, mitochondrial swelling, pronounced depletion of glycogen stores, and focal myofibrillary disorganization. Group B showed near normal myocardial ultrastructure with increased glycogen stores and minimal mitochondrial swelling. Morphometric analysis revealed a statistically significant increase in the degree of mitochondrial swelling (51%) in Group A compared with Group B after reperfusion (p less than 0.001). Thus, blood K+ cardioplegia resulted in better preservation of myocardial ultrastructure, lower ventricular filling pressure, and lesser CPK-MB release compared with this particular electrolyte cardioplegia.