Intravasal microdialysis is superior to intramyocardial microdialysis in detecting local ischaemia in experimental porcine myocardial infarction

Objective: A novel application of microdialysis was studied, where myocardial outflow of energy metabolites was monitored by intravasal microdialysis in the myocardial venous outflow during ischaemia and reperfusion. These levels where related to levels monitored by microdialysis catheters placed intramyocardially. Methods: Microdialysis catheters were introduced into the great cardiac vein (GCV), ischaemic myocardium and non-ischaemic myocardium in 10 anaesthetized pigs. The left anterior descending coronary artery was occluded for 60 min in five pigs and five pigs served as controls. Ischaemia was followed by 120 min of reperfusion. Microdialysis samples were analysed for glucose, lactate, pyruvate and glycerol. Venous lactate and glucose levels were measured by blood samples from the femoral vein. Results: All animals subjected to ischaemia developed myocardial infarction. Lactate, lactate/pyruvate ratio and glycerol increased in the microdialysis samples from the GCV and the catheter placed in ischaemic myocardium while no changes were detected in samples from the catheter placed in the non-ischaemic myocardium. Conclusion: In this study, we have demonstrated that intravasal microdialysis catheters rapidly and reliably detect local myocardial ischaemia, while intramyocardially placed microdialysis catheters will not show these changes if placed in a non-ischaemic area.