Newly Shaped Intra-Aortic Balloons Improve the Performance of Counterpulsation at the Semirecumbent Position: An In Vitro Study.

Christina Kolyva,Ashraf W Khir,John R Pepper

doi:10.1111/aor.12791

Christina Kolyva, Ashraf W Khir + Show 1 more

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https://doi.org/10.1111/aor.12791

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Abstract

The major hemodynamic benefits of intra‐aortic balloon pump (IABP) counterpulsation are augmentation in diastolic aortic pressure (P aug) 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 P aug 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.

Highlights

An enhanced IAB consisting of internal and external IABs that are both connected to the same intra-aortic balloon pump (IABP) driving system has been tested; the internal IAB is positioned in the descending aorta and the external IAB is positioned inside a chamber, the output of which drains through a conduit just upstream the internal IAB tip [13]
Among the newly shaped IABs tested, Shape 2 consistently achieved, in terms of absolute magnitude, larger decrease in end-diastolic aortic pressure (DedP) at angles than the cylindrical IAB. This DedP was gradually diminished by angle, but to a lesser degree compared to the cylindrical IAB
During inflation Shape 1 displayed a more stable behavior with increasing angle compared to the cylindrical IAB; for example, with an increase in angle from 0 to 408, diastolic “aortic” pressure augmentation dropped only by 45% and by 33% of the drop reached with the cylindrical IAB

Summary

Introduction

The main direct hemodynamic benefits of the IABP are augmentation in diastolic aortic pressure (Paug_ao) due to inflation and reduction in enddiastolic aortic pressure (DedPao) due to deflation These effects are achieved through blood volume displacement upstream the IAB tip, with blood pushed toward the aortic arch during inflation and sucked away from the aortic arch during deflation. An enhanced IAB consisting of internal and external IABs that are both connected to the same IABP driving system has been tested; the internal IAB is positioned in the descending aorta and the external IAB is positioned inside a chamber, the output of which drains through a conduit just upstream the internal IAB tip [13] This design provided added capacity for early diastolic aortic pressure augmentation and end-diastolic LV unloading, delivered directly in the ascending aorta. A shorter and wider version of the cylindrical IAB that is currently used clinically has been tested very recently with favorable hemodynamic results [14]

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