Flow dynamic comparison of in-situ internal thoracic and gastroepiploic arterial conduits: Experimental study

Objective: We tried to experimentally clarify the flow dynamic differences under flow competitive conditions between the internal thoracic artery (ITA) and gastroepiploic artery (GEA) as in-situ arterial bypass conduits. Methods: The ITA and the GEA were anastomosed close together to the left anterior descending artery (LAD) in 8 pigs. Flow characteristics of the ITA and the GEA were analyzed using a transit time flowmeter under the following flow competitive conditions; condition A: the ITA, GEA and LAD were left open, condition B: either of the ITA or GEA were clamped and the LAD was left open, condition C: the ITA and GEA were open but the proximal LAD was clamped, condition D: either of the ITA or GEA were clamped and the proximal LAD was also clamped. Results: The flow volume of the ITA was significantly (p<0.001) greater than that of the GEA in condition A (27±11 ml/min vs. -4±9 ml/min), B (26±17 ml/min vs. -1±14 ml/min) and C (38±14 ml/nun vs. 0±4 ml/min), but did not differ (p=0.685) in condition D (29±6 ml/min vs. 31±14 ml/min). Retrograde flow in systole and antegrade flow in diastole was seen in the GEA in condition A, B and C. Conclusion: Under flow competitive conditions, flow of the GEA was inferior to that of the ITA. These data suggested that the GEA is more sensitive to competitive flow than the ITA. This may be due to anatomical differences between these in-situ bypass conduits.