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Patent side branches do not affect coronary blood flow in internal thoracic artery-left anterior descending
C Pragliola1, M Gaudino, G Bombardieri
1Departments of Cardiac Surgery and Anesthesiology, Catholic University, Rome, Italy.
Insights
Internal thoracic artery side branches have minimal blood flow, even during vasodilation. This suggests that significant coronary flow steal from these side branches is unlikely in patients undergoing arterial grafting.
Area of Science:
- Cardiovascular Surgery
- Vascular Biology
- Surgical Innovation
Background:
- Internal thoracic artery (ITA) grafts are crucial in coronary artery bypass grafting.
- Concerns exist regarding potential "flow steal" from coronary circulation by ITA side branches.
Purpose of the Study:
- To quantify the hemodynamic significance of ITA side branches.
- To determine if ITA side branches compromise coronary perfusion.
Main Methods:
- Constructed ITA-left anterior descending anastomosis in pigs without side branch interruption.
- Measured proximal and distal ITA flow and pressures at baseline and during adenosine infusion.
- Repeated measurements after surgical occlusion of all ITA side branches.
Main Results:
- ITA side branches accounted for 18% of proximal ITA flow at baseline.
- Adenosine infusion increased cardiac index by 220% and proximal ITA flow by 368% without altering side branch flow percentage.
- Occluding side branches did not significantly increase distal ITA flow.
Conclusions:
- ITA side branch blood flow is minimal, both at baseline and during vasodilation.
- Clinically significant "flow steal" from the coronary circulation to ITA side branches is unlikely.
Background:
It has been reported that large side branches of internal thoracic artery grafts may steal flow from the coronary circulation. Material an.
Methods:
To assess the importance of the side branches, we measured the proximal and distal flow and pressures (mean subclavian artery pressure and mean arterial anastomotic pressure) at baseline and during infusion of adenosine (0.5 mg/kg/min) in 10 Landrace pigs in which an internal thoracic artery-left anterior descending anastomosis was constructed without interruption of the side branches. The difference between proximal and distal flow was considered to represent the blood flow of the internal thoracic artery side branches. Measurements were then repeated after surgical occlusion of all the side branches.
Results:
At baseline, blood flow of the side branches represented 18% of the total flow in the proximal internal thoracic artery, and this percentage remained constant under the infusion of adenosine, which caused a 220% increase of the cardiac index and a 368% increase of the proximal flow. The infusion reduced the gradient along the left internal thoracic artery (mean subclavian artery pressure-mean arterial anastomotic pressure) from 15 to 10 mm Hg (P =.02) as the result of a lower mean subclavian artery pressure, although the mean arterial anastomotic pressure remained constant. Interruption of all the side branches resulted in a small and not significant increase in distal flow even after adenosine infusion.
Conclusion:
These observations suggest that blood flow in the side branches is minimal either at baseline and under combined systemic and coronary vasodilation. Clinically significant flow steal from the coronary circulation to the internal thoracic artery side branches seems then unlikely.