Ultrastructural integrity of human ventricular myocardium following cardioplegic arrest

Area of Science:

• Cardiology
• Cardiac Surgery
• Cellular Biology

Background:

• Coronary artery bypass grafting (CABG) requires temporary interruption of blood flow.
• Myocardial protection during aortic cross-clamping is critical.
• Hypothermic cardioplegia is a common method for myocardial preservation.

Purpose of the Study:

• To evaluate the ultrastructural effects of hypothermic potassium cardioplegia on human ventricular myocardium.
• To assess potential myocardial injury induced by aortic cross-clamping and cardioplegic perfusion during CABG.

Main Methods:

• Electron microscopy was used to examine ventricular myocardium from 6 patients before and after aortic cross-clamping.
• A specific protocol of hypothermic cardioplegia using intermittent aortic root perfusion with cold blood and potassium chloride was employed.
• Cross-clamp times ranged from 66 to 125 minutes.

Main Results:

• The primary ultrastructural change observed post-bypass was myocardiocytic pooling of glycogen.
• No abnormalities were detected in the intramyocardial capillary bed attributable to the bypass procedure or cardioplegic solution.
• The observed glycogen pooling was not considered indicative of significant myocardial injury.

Conclusions:

• Hypothermic potassium cardioplegia, as administered in this study, does not appear to cause ultrastructural injury to the human myocardium.
• The method is considered safe for myocardial preservation during coronary bypass operations.
• Further research may explore the functional implications of glycogen pooling.