title: Newly Shaped Intra-Aortic Balloons Improve the Performance of Counterpulsation at the Semirecumbent Position: An In Vitro Study.
abstract: 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 in the semirecumbent 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. 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 one cylindrical and six newly shaped IABs at angles 0, 10, 20, 30, and 40°. Pressure was measured continuously at the aortic root during 1:1 and 1:4 IABP support. 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 0 to 40°. During inflation Shape 1 displayed a more stable behavior with increasing angle compared to the cylindrical IAB; with an increase in angle from 0 to 40°, 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. Newly shaped IABs could allow for IABP therapy to become more efficient for patients nursed at the semirecumbent 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.
authors.affiliation: Department of Mechanical Engineering, Brunel University, Uxbridge.
authors.forename: Christina
authors.initials: C
authors.lastname: Kolyva
authors.affiliation: National Heart and Lung Institute, Imperial College London, London, UK.
authors.forename: John R
authors.initials: JR
authors.lastname: Pepper
authors.affiliation: Department of Mechanical Engineering, Brunel University, Uxbridge.
authors.forename: Ashraf W
authors.initials: AW
authors.lastname: Khir
mesh_terms: D001794:Blood Pressure; D004867:Equipment Design; D006439:Hemodynamics; D006801:Humans; D007423:Intra-Aortic Balloon Pumping / Q000295:instrumentation*; D008955:Models, Cardiovascular; D056888:Patient Positioning / Q000379:methods; D016276:Ventricular Function
keywords: Balloon efficacy; Balloon shape; Counterpulsation; Hemodynamics; Intra-aortic balloon pump; Semirecumbent