Newly shaped intra-aortic balloons improve the performance of counterpulsation at the semirecumbent position: An in vitro study

Abstract

Copyright © 2016 The Authors. Objectives: The major hemodynamic benefits of intra-aortic balloon pump (IABP) counterpulsation are augmentation in diastolic aortic pressure (Paug), during inflation, and decrease in end-diastolic aortic pressure (ΔedP), during deflation. When the patient is nursed at the semi-recumbent position these benefits are diminished. Attempts to change the shape of the IAB in order to limit or prevent this deterioration have been scarce. The aim of the present study was to investigate the hemodynamic performance of six new IAB shapes, and compare it to that of a traditional cylindrical IAB. Methods: A mock circulation system, featuring an artificial left ventricle and an aortic model with 11 branches and physiological resistance and compliance, was used to test 1 cylindrical and 6 newly shaped IABs at angles 0o, 10o, 20o, 30o and 40o. Pressure was measured continuously at the aortic root during 1:1 and 1:4 IABP support. Results: Shape 2 was found to consistently achieve, in terms of absolute magnitude, larger ΔedP at angles than the cylindrical IAB. Although ΔedP was gradually diminished with angle, it did so to a lesser degree than the cylindrical IAB; this diminishment was only 53% (with frequency 1:1) and 40% (with frequency 1:4) of that of the cylindrical IAB, when angle increased from 0o to 40o. During inflation Shape 1 displayed a more stable behaviour with increasing angle compared to the cylindrical IAB; with an increase in angle from 0o to 40o, diastolic aortic pressure augmentation dropped only by 45% (with frequency 1:1) and by 33% (with frequency 1:4) of the drop reached with the cylindrical IAB. After compensating for differences in nominal IAB volume, Shape 1 generally achieved higher Paug over most angles. Conclusions: Newly shaped IABs could allow for IABP therapy to become more efficient for patients nursed at the semi-recumbent position. The findings promote the idea of personalized rather than generalized patient therapy for the achievement of higher IABP therapeutic efficiency, with a choice of IAB shape that prioritizes the recovery of those hemodynamic indices that are more in need of support in the unassisted circulation.