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Does the internal thoracic artery graft delay the recovery of myocardial metabolism?
V Rao1, G T Christakis, R D Weisel
1Division of Cardiovascular Surgery, Toronto Hospital, Ontario, Canada.
Insights
The left internal thoracic artery (LITA) graft offers comparable myocardial protection to saphenous vein grafts during coronary artery bypass grafting. Advances in cardioplegia ensure similar high-energy phosphate levels, supporting LITA graft use.
Area of Science:
- Cardiovascular Surgery
- Cardiac Metabolism
- Myocardial Protection
Background:
- Left internal thoracic artery (LITA) grafts show superior long-term patency compared to saphenous vein grafts for the left anterior descending artery.
- Surgeons' reluctance to use LITA grafts stems from concerns about delivering cardioplegia to the left anterior descending artery territory.
Purpose of the Study:
- To compare myocardial high-energy phosphate levels and metabolites between LITA and saphenous vein grafts to the left anterior descending artery.
- To assess the impact of LITA graft use on myocardial protection during coronary artery bypass grafting.
Main Methods:
- Prospective comparison of myocardial high-energy phosphates and metabolites in patients receiving LITA versus saphenous vein grafts.
- Obtained right and left ventricular biopsy specimens at three time points: pre-cross-clamping, post-cross-clamp removal, and 10 minutes post-reperfusion.
Main Results:
- No significant differences in right ventricular metabolites between LITA and saphenous vein graft groups.
- Improved myocardial protection observed over time, with a higher proportion of LITA graft patients in the later period (80% vs. 63%).
- Patients receiving LITA grafts with cold antegrade cardioplegia demonstrated better preservation of myocardial high-energy phosphates.
Conclusions:
- Modern myocardial protection strategies effectively preserve high-energy phosphate levels post-cardioplegic arrest.
- LITA graft utilization in elective coronary artery bypass grafting does not negatively impact myocardial metabolism.
- Further research is needed to evaluate LITA graft use in urgent or emergent cardiac procedures.
Background:
The left internal thoracic artery (LITA) bypass graft to the left anterior descending artery has greater long-term patency than a saphenous vein graft. However, surgeons may be reluctant to use the LITA graft in some patients because they are unable to deliver cardioplegia to the left anterior descending artery territory.
Methods:
We compared the myocardial levels of high-energy phosphates and their metabolites in patients who received an LITA graft with those in patients who received a saphenous vein graft to the left anterior descending artery territory during elective coronary artery bypass grafting. Right and left ventricular biopsy specimens were obtained at three times: before aortic cross-clamping, after cross-clamp removal, and after 10 minutes of reperfusion.
Results:
No differences were found between the LITA graft group and the saphenous vein graft group in any right ventricular metabolites. There was an improvement in myocardial protection over time and a higher proportion of LITA graft patients in the late time period (early group, 63% versus late group, 80%; p < 0.01). Within each time period, there were no differences between the LITA and saphenous vein graft groups. Among patients receiving cold antegrade cardioplegia, the myocardial levels of high-energy phosphates were better preserved in those receiving an LITA graft.
Conclusions:
Advances in myocardial protection have led to improved preservation of high-energy phosphate levels after cardioplegic arrest. In patients undergoing elective coronary artery bypass grafting, the use of an LITA graft does not adversely affect myocardial metabolism. Further investigations are required to determine the effects of the use of the LITA during urgent or emergent procedures.
