Effects of intraaortic balloon counterpulsation on middle cerebral artery blood flow velocities

Introduction

The intraaortic balloon pump has been shown to improve cardiac output and diastolic coronary flow. The aim of our study was to determine the effects of intraaortic counterpulsation (IABP) on cerebral blood flow velocities measured on the middle cerebral artery.

Methods

In 11 cardiac surgery patients receiving IABP postoperatively, blood flow velocities in the middle cerebral artery were assessed by transcranial Doppler (TCD). In each patient, measurements of V_max, V_mean and V_min were performed at four different pump settings: without support (WS), and at pump assist pulse with ratio 1:1, 1:2 and 1:3.

Results

Repeated-measures analysis of variance: P = 0.0006, considered extremely significant variation of TCD measurements among IABP settings. Comparing all pairs of V_max, V_mean and V_min values, we found that V_max and especially V_mean are significantly greater at the 1:2 and 1:3 pump settings, but not at the 1:1 setting. We also found that the end diastolic velocities (V_min) were significant lower during the pump deflation. None of our patients had a significant diastolic flow velocity reversal during the pump deflation.

Conclusion

Left ventricular support with IABP significantly changed the flow velocity pattern of our patients. The pump significantly increased the V_max and the V_mean at the 1:2 and 1:3 settings because of pump inflation during the diastole. We suggest that the velocities did not change at the 1:1 setting because the end-diastolic flow velocities reduce during every pulse, according to pump deflation.

Table 1 abstract