Change in myocardial oxygen consumption employing continuous-flow LVAD with cardiac beat synchronizing system, in acute ischemic heart failure models

Umeki, Akihide; Nishimura, Takashi; Takewa, Yoshiaki; Ando, Masahiko; Arakawa, Mamoru; Kishimoto, Yuichiro; Tsukiya, Tomonori; Mizuno, Toshihide; Kyo, Shunei; Ōno, Minoru; Taenaka, Yoshiyuki; Tatsumi, Eisuke

doi:10.1007/s10047-012-0682-0

Cited by 21 publications

(19 citation statements)

References 49 publications

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“…The tVAD simulation was intended as a baseline experiment that represents the use of tVADs in clinical application today. There are numerous studies that have investigated augmented pulsatility in tVADs through speed modulation [1,3,4,16,26,27,33,34]. These studies have shown improved levels of pulsatility, left ventricular unloading and blood flow through the aortic valve, but were exceeded by the values of our pVAD simulation.…”

Section: Discussionmentioning

confidence: 84%

“…Previous studies have investigated synchronization ratios (1:2 and 1:4) lower than the HR under one given phase-shift setting [24] with the intention of establishing a weaning protocol. The importance of considering the pump timing and systolic fraction as an integral part of the investigation has been shown in vivo by [2] for pVADs and by [1,3,4,26,33,34] both in silico and in vivo for tVADs.…”

Section: Discussionmentioning

confidence: 99%

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High-frequency operation of a pulsatile VAD – a simulation study

Rebholz

Amacher

Petrou

et al. 2017

Biomedical Engineering / Biomedizinische Technik

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Ventricular assist devices (VADs) are mechanical blood pumps that are clinically used to treat severe heart failure. Pulsatile VADs (pVADs) were initially used, but are today in most cases replaced by turbodynamic VADs (tVADs). The major concern with the pVADs is their size, which prohibits full pump body implantation for a majority of patients. A reduction of the necessary stroke volume can be achieved by increasing the stroke frequency, while maintaining the same level of support capability. This reduction in stroke volume in turn offers the possibility to reduce the pump's overall dimensions. We simulated a human cardiovascular system (CVS) supported by a pVAD with three different stroke rates that were equal, two-or threefold the heart rate (HR). The pVAD was additionally synchronized to the HR for better control over the hemodynamics and the ventricular unloading. The simulation results with a HR of 90 bpm showed that a pVAD stroke volume can be reduced by 71%, while maintaining an aortic pulse pressure (PP) of 30 mm Hg, avoiding suction events, reducing the ventricular stroke work (SW) and allowing the aortic valve to open. A reduction by 67% offers the additional possibility to tune the interaction between the pVAD and the CVS. These findings allow a major reduction of the pVAD's body size, while allowing the physician to tune the pVAD according to the patient's needs.

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

High-frequency operation of a pulsatile VAD – a simulation study

Rebholz

Amacher

Petrou

et al. 2017

Biomedical Engineering / Biomedizinische Technik

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“…Changes in LVEW with synchronous LVAD modulation timing was described by Jahren et al 14 in a mock flow loop and by umeki et al 13 in an acute IHF model. Ando et al 15 previously demonstrated that low rPM modulation amplitudes increased pulse pressure even at very low mean LVAD flow.…”

Section: Discussionmentioning

confidence: 93%

“…[5][6][7][8][9] Augmenting aortic pressure pulsatility via CF LVAD flow and/or motor speed modulation algorithms has been proposed to minimize adverse events, prevent aortic insufficiency, alter ventricular unloading, reduce myocardial oxygen consumption, and improve myocardial recovery. [10][11][12][13][14][15][16][17][18][19][20][21] The potential hemodynamic benefits of CF LVAD modulation evaluated in a computer simulation model with candidate pump speed modulation algorithms identified for feasibility testing. 22 Based on these findings, hemodynamic performance of a clinically approved CF LVAD operated at constant pump speed, and asynchronous, synchronous copulsation, and synchronous counterpulsation modulated pump speed were further investigated in a mock flow loop model, and acutely in a chronic ischemic heart failure (IHF) bovine model (n = 3) to demonstrate feasibility.…”

mentioning

confidence: 99%

Feasibility of Pump Speed Modulation for Restoring Vascular Pulsatility with Rotary Blood Pumps

Ising¹,

Sobieski²,

Slaughter³

et al. 2015

ASAIO Journal

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Continuous flow (CF) left ventricular assist devices (LVAD) diminish vascular pressure pulsatility, which may be associated with clinically reported adverse events including gastrointestinal bleeding, aortic valve insufficiency, and hemorrhagic stroke. Three candidate CF LVAD pump speed modulation algorithms designed to augment aortic pulsatility were evaluated in mock flow loop and ischemic heart failure (IHF) bovine models by quantifying hemodynamic performance as a function of mean pump speed, modulation amplitude, and timing. Asynchronous and synchronous copulsation (high revolutions per minute [RPM] during systole, low RPM during diastole) and counterpulsation (low RPM during systole, high RPM during diastole) algorithms were tested for defined modulation amplitudes (±300, ±500, ±800, and ±1,100 RPM) and frequencies (18.75, 37.5, and 60 cycles/minute) at low (2,900 RPM) and high (3,200 RPM) mean LVAD speeds. In the mock flow loop model, asynchronous, synchronous copulsation, and synchronous counterpulsation algorithms each increased pulse pressure (ΔP = 931%, 210%, and 98% and reduced left ventricular external work (LVEW = 20%, 22%, 16%). Similar improvements in vascular pulsatility (1,142%) and LVEW (40%) were observed in the IHF bovine model. Asynchronous modulation produces the largest vascular pulsatility with the advantage of not requiring sensor(s) for timing pump speed modulation, facilitating potential clinical implementation.

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“…A square-wave speed profile was applied by Bearnson et al [11] and Bourque et al [12] to increase arterial pulse pressure, where the speed profile was not synchronized to the cardiac cycle. Different types of speed profiles, synchronized to the natural cardiac cycle, have been applied in silico and in vitro to analyze their influence on perfusion, pulse pressure and ventricular unloading [13][14][15][16][17][18]. In vivo experiments have been conducted to validate this approach [19,20].…”

Section: Introductionmentioning

confidence: 99%

Numerical Optimal Control of Turbo Dynamic Ventricular Assist Devices

et al. 2013

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Abstract:The current paper presents a methodology for the derivation of optimal operating strategies for turbo dynamic ventricular assist devices (tVADs). In current clinical practice, tVADs are typically operated at a constant rotational speed, resulting in a blood flow with a low pulsatility. Recent research in the field has aimed at optimizing the interaction between the tVAD and the cardiovascular system by using predefined periodic speed profiles. In the current paper, we avoid the limitation of using predefined profiles by formulating an optimal-control problem based on a mathematical model of the cardiovascular system and the tVAD. The optimal-control problem is solved numerically, leading to cycle-synchronized speed profiles, which are optimal with respect to an arbitrary objective. Here, an adjustable trade-off between the maximization of the flow through the aortic valve and the minimization of the left-ventricular stroke work is chosen. The optimal solutions perform better than constant-speed or sinusoidal-speed profiles for all cases studied. The analysis of optimized solutions provides insight into the optimized Bioengineering 2014, 1 23 interaction between the tVAD and the cardiovascular system. The numerical approach to the optimization of this interaction represents a powerful tool with applications in research related to tVAD control. Furthermore, patient-specific, optimized VAD actuation strategies can potentially be derived from this approach.

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Change in myocardial oxygen consumption employing continuous-flow LVAD with cardiac beat synchronizing system, in acute ischemic heart failure models

Cited by 21 publications

References 49 publications

High-frequency operation of a pulsatile VAD – a simulation study

High-frequency operation of a pulsatile VAD – a simulation study

Feasibility of Pump Speed Modulation for Restoring Vascular Pulsatility with Rotary Blood Pumps

Numerical Optimal Control of Turbo Dynamic Ventricular Assist Devices

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