Scaling the Low-Shear Pulsatile TORVAD for Pediatric Heart Failure

Gohean, Jeffrey R.; Larson, Erik R.; Hsi, Brian; Kurusz, Mark; Smalling, Richard W.; Longoria, Raul G.

doi:10.1097/mat.0000000000000460

Cited by 23 publications

(18 citation statements)

References 32 publications

(33 reference statements)

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“…The pulsatile TORVAD pump is a 15 mL stroke volume device with a maximum flow rate of 4 L/min. This pump can provide full support to pediatric patients with BSAs between 0.6 and 1.5 m 2 .…”

mentioning

confidence: 99%

The Progress in the Novel Pediatric Rotary Blood Pump Sputnik Development

et al. 2018

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In this work, the study results of an implantable pediatric rotary blood pump (PRBP) are presented. They show the results of the numerical simulation of fluid flow rates in the pump. The determination method of the backflows and stagnation regions is represented. The operating points corresponding to fluid flow rates of 1, 3, and 5 L/min for 75-80 mm Hg pressure head are investigated. The study results have shown that use of the pump in the 1 L/min operating point can potentially lead to the appearance of backflows and stagnation regions. In the case of using pumps in fluid flow rates ranging from 3 to 5 L/min, the number of stagnation regions decreases and the fluid flow rate changes marginally. Using the pump in this flow rate range is considered judicious. The study shows an increase in shear stress with an increase in fluid flow rates, while there is no increase in shear stress above the critical condition of 150 Pa (which does not allow us to reliably speak about the increased risk of blood cell damage). The aim of this work was to design, prototype, and study interaction of the Sputnik PRBP with the cardiovascular system. A three-dimensional model of Sputnik PRBP was designed with the following geometrical specifications: flow unit length of 51.5 mm, flow unit diameter of 10 mm, and spacing between the rotor and housing of 0.1 mm. Computational fluid dynamics studies were used to calculate head pressure-flow rate (H-Q) curves at rotor speeds ranging from 10 000 to 14 000 rpm (R = 0.866 between numerical simulation and experiment) and comparing flow patterns at various points of the flow rate operating range (1, 3, and 5 L/min) for operating pressures ranging from 75 to 80 mm Hg. It is noted that when fluid flow rate changes from 1 L/min to 3 L/min, significant changes are observed in the distribution of zero flow zones. At the inlet and outlet of the pump, when going to the operating point of 3 L/min, zones of stagnation become minuscule. The shear stress distribution was calculated along the pump volume. The volume in which shear stress exceed 150 Pa is less than 0.38% of the total pump volume at flow rates of 1, 3, and 5 L/min. In this study, a mock circulatory system (MCS) allowing simulation of physiological cardiovascular characteristics was used to investigate the interaction of the Sputnik PRBP with the cardiovascular system. MCS allows reproducing the Frank-Starling autoregulation mechanism of the heart. PRBP behavior was tested in the speed range of 6 000 to 15 000 rpm. Decreased contractility can be expressed in a stroke volume decrease approximately from 18 to 4 mL and ventricle systolic pressure decrease approximately from 92 to 20 mm Hg. The left ventricle becomes fully supported at a pump speed of 10 000 rpm. At a pump speed of 14 000 rpm, the left ventricle goes into a suction state in which fluid almost does not accumulate in the ventricle and only passes through it to the pump. The proposed PRBP showed potential for improved clinical outcomes in pediatric patients with a body surface area g...

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“…The pulsatile TORVAD pump is a 15 mL stroke volume device with a maximum flow rate of 4 L/min. This pump can provide full support to pediatric patients with BSAs between 0.6 and 1.5 m 2 .…”

mentioning

confidence: 99%

The Progress in the Novel Pediatric Rotary Blood Pump Sputnik Development

et al. 2018

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“…[25][26][27] Of note, the new design of next-generation LVADs such as toroidal-flow LVAD has focused on providing full hemodynamic support with lower shear rate of approximately 2857 s −1 to reduce blood trauma. 46,47 Second, our current blood-shearing experiments were performed at room temperature instead of body temperature (37°C) and aggregate size was assessed from two-dimensional images rather than as three-dimensional volumes. Third, the current work was focused on understanding the mechanobiology of vWF multimers interaction with platelets under shear and how that influences the formation sizes of platelet aggregates.…”

Section: Limitationsmentioning

confidence: 99%

Shear‐dependent platelet aggregation size

Chan

Inoue

et al. 2020

Artificial Organs

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“…2,3,6 A pVAD is a volume displacement pump in which the blood is not propelled by shear or centrifugal forces, but which instead works with a pumping mechanism that is more like the native heart. Other pulsatile pumping concepts proposed such as the TORVAD 14 exist, but exceed the WSS levels suitable for endothelialization. Computational fluid dynamics (CFD) studies with displacement pump models mimicking existing pVAD shapes have shown maximum WSS to be between 10 and 16 Pa. 15,16 Physiological levels of WSS were reported to average around 6 Pa 17,18 and peak stresses in human pre-capillary arterioles close to 15 Pa. 19 Additionally, the ECs are exposed to a combined load of shear and strain on the pulsating membrane in a pVAD.…”

Section: Rebholz Et Almentioning

confidence: 99%

“…A pVAD is a volume displacement pump in which the blood is not propelled by shear or centrifugal forces, but which instead works with a pumping mechanism that is more like the native heart. Other pulsatile pumping concepts proposed such as the TORVAD exist, but exceed the WSS levels suitable for endothelialization. Computational fluid dynamics (CFD) studies with displacement pump models mimicking existing pVAD shapes have shown maximum WSS to be between 10 and 16 Pa .…”

Section: Introductionmentioning

confidence: 99%

Short‐term physiological response to high‐frequency‐actuated pVAD support

et al. 2019

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Ventricular assist devices (VADs) are an established treatment option for heart failure (HF). However, the devices are often plagued by material‐related hemocompatibility issues. In contrast to continuous flow VADs with high shear stresses, pulsatile VADs (pVADs) offer the potential for an endothelial cell coating that promises to prevent many adverse events caused by an insufficient hemocompatibility. However, their size and weight often precludes their intracorporeal implantation. A reduction of the pump body size and weight of the pump could be achieved by an increase in the stroke frequency while maintaining a similar cardiac output. We present a new pVAD system consisting of a pump and an actuator specifically designed for actuation frequencies of up to 240 bpm. In vitro and in vivo results of the short‐term reaction of the cardiovascular system show no significant changes in left ventricular and aortic pressure between actuation frequencies from 60 to 240 bpm. The aortic pulsatility increases when the actuation frequency is raised while the heart rate remains unaffected in vivo. These results lead us to the conclusion that the cardiovascular system tolerates short‐term increases of the pVAD stroke frequencies.

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Scaling the Low-Shear Pulsatile TORVAD for Pediatric Heart Failure

Cited by 23 publications

References 32 publications

The Progress in the Novel Pediatric Rotary Blood Pump Sputnik Development

The Progress in the Novel Pediatric Rotary Blood Pump Sputnik Development

Shear‐dependent platelet aggregation size

Short‐term physiological response to high‐frequency‐actuated pVAD support

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