• Kevin G Soucy, Guruprasad A Giridharan, Young Choi, Michael A Sobieski, Gretel Monreal, Allen Cheng, Erin Schumer, Mark S Slaughter, and Steven C Koenig.
• Departments of a?>Cardiovascular and Thoracic Surgery; Bioengineering, University of Louisville, Louisville, Kentucky.
• J. Heart Lung Transplant. 2015 Jan 1;34(1):122-31.

BackgroundRotary blood pumps operate at a constant speed (rpm) that diminishes vascular pulsatility and variation in ventricular end-systolic and end-diastolic volumes, which may contribute to adverse events, including aortic insufficiency and gastrointestinal bleeding. In this study, pump speed modulation algorithms for generating pulsatility and variation in ventricular end-systolic and end-diastolic volumes were investigated in an ischemic heart failure (IHF) bovine model (n = 10) using a clinically implanted centrifugal-flow left ventricular assist device (LVAD).MethodsHemodynamic and hematologic measurements were recorded during IHF baseline, constant pumps speeds, and asynchronous (19-60 cycles/min) and synchronous (copulse and counterpulse) pump speed modulation profiles using low relative pulse speed (±25%) of 3,200 ± 800 rpm and high relative pulse speed (±38%) of 2,900 ± 1,100 rpm. End-organ perfusion, hemodynamics, and pump parameters were measured to characterize pulsatility, myocardial workload, and LVAD performance for each speed modulation profile.ResultsSpeed modulation profiles augmented aortic pulse pressure, surplus hemodynamic energy, and end-organ perfusion (p < 0.01) compared with operation at constant speed. Left ventricular external work and myocardial oxygen consumption were significantly reduced compared with IHF baseline (p < 0.01) but at the expense of higher LVAD power consumption.ConclusionsPump speed modulation increases pulsatility and improves cardiac function and end-organ perfusion, but the asynchronous mode provides the technologic advantage of sensorless control. Investigation of asynchronous pump speed modulation during long-term support is warranted to test the hypothesis that operating an LVAD with speed modulation will minimize adverse events in patients supported by an LVAD that may be associated with long-term operation at a constant pump speed.Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

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