Superior mesenteric flow pattern during counterpulsation: is simply a shorter balloon the solution for visceral hypoperfusion?

OBJECTIVES: We studied the flow pattern in the superior mesenteric artery (SMA) during intra-aortic balloon pump support, comparing 2 intra-aortic balloons of 2 different lengths. METHODS: Sixteen Landrace pigs (mean weight 84.0 kg +/- 6.0) were used in this study. The animals were randomly assigned to 2 groups: group 1 received an 8-Fr, 40-ml standard balloon; group 2 received an 8-Fr, 40-ml short balloon. SMA flow was measured during early, mid- and telediastole. RESULTS: The standard balloon led to a reduction in SMA flow in early diastole (P < 0.001), a negative flow in mid-diastole (P < 0.001) and a reincrease in telediastole (P < 0.001). In contrast, in early diastole a significant reduction was observed with the short balloon (P < 0.001), followed by another drop in mid-diastole (P < 0.001), without reaching negative values and by a telediastolic increase (P < 0.001). SMA flows were comparable between balloons during early diastole (P = 0.66), whereas they were higher with the short balloon during mid (P < 0.001) and telediastole (P = 0.02). Overall, the diastolic area was significantly larger when the short balloon was used (P < 0.001). Finally, during counterpulsation, mesenteric resistances increased significantly (P < 0.001), although, with the short balloon, they were lower than with the standard balloon (P = 0.01). CONCLUSIONS: Despite better overall mean mesenteric diastolic flow, the short balloon leads to early- and mid-diastolic flow reduction, although to a lesser extent than the standard intra-aortic balloon pump balloon. Our data are a call for improvement in the design of the short balloon.