First name
Amy
Last name
Throckmorton

Title

Integrated Long-term Multifunctional Pediatric Mechanical Circulatory Assist Device.

Year of Publication

2020

Date Published

2020 Nov 15

ISSN Number

1525-1594

Abstract

<p>There continues to be limited, viable VAD technology options to support the dysfunctional states of pediatric heart failure. To address this need, we are developing a magnetically suspended, versatile pumping technology that uniquely integrates two blood pumps in a series configuration within a single device housing. This device enables operational switching from the usage of one pump to another as needed for clinical management or to support growth and development of the pediatric patient. Here we present the initial design where we conducted a virtual fit study, the Taguchi Design Optimization Method, iterative design to develop pump geometries. Computational tools were used to estimate the pressure generation, capacity delivery, hydraulic efficiency, fluid stress levels, exposure time to stresses, blood damage index, and fluid forces on the impellers. Prototypes of the pumps were tested in a hydraulic flow loop using a blood analog water-glycerin solution. Both designs demonstrated the capability to generate target pressures and flows. Blood damage estimations were below threshold levels and achieved design requirements; however, maximum scalar stress levels were above the target limit. Radial and axial forces were less than 1 N and 10 N, respectively. The performance data trends for physical prototypes correlated with theoretical expectations. The centrifugal prototype was able to generate slightly higher pressure rises than numerical predictions. In contrast, the axial prototype outperformed the computational studies. Experimental data were both repeatable and reproducible. The findings from this research are promising, and development will continue.</p>

DOI

10.1111/aor.13863

Alternate Title

Artif Organs

PMID

33191508

Title

Fluid-structure interaction modeling in cardiovascular medicine - A systematic review 2017-2019.

Year of Publication

2020

Date Published

2020 Feb 17

ISSN Number

1873-4030

Abstract

<p>Finite element analysis (FEA) and computational fluid dynamics (CFD) are generally insufficient independently to model the physics of the cardiovascular system. Individually, they are unable to resolve the interplay between the solid and fluid domains, and the interplay is integral to the functioning of the system. The use of fluid-structure interaction (FSI) methods overcomes these shortcomings by providing the means to couple the fluid and structural domains. In the last decade, the utilization of FSI has greatly increased in cardiovascular engineering. In this study, we conducted a systematic review process of more than 1000 journal articles to investigate the implementation of One-Way and Two-Way FSI for cardiovascular applications. We explored the utility of FSI to study aneurysms, the hemodynamics of patient anatomies, native and prosthetic heart valve dynamics, flow and hemodynamics of blood pumps, and atherosclerosis. Computational resource requirements, implementation strategies and future directions of FSI for cardiovascular applications are also discussed.</p>

DOI

10.1016/j.medengphy.2020.01.008

Alternate Title

Med Eng Phys

PMID

32081559

Title

New Versatile Dual-Support Pediatric Heart Pump.

Year of Publication

2019

Date Published

2019 Jun 04

ISSN Number

1525-1594

Abstract

<p>Mechanical circulatory support (MCS) devices for pediatric patients continue to lag in development behind those for adults. There is no heart pump with the design innovation to support dysfunctional states of heart failure and the anatomic heterogeneity of cardiac defects in pediatric patients. To address this unmet need, we are developing a versatile MCS technology with two separate blood pumps under one housing, whereby a centrifugal pump rotates around an axial pump. In this study, we advanced the design with a new inducer for the axial pump component and flat inlet volute for the centrifugal pump component. We conducted computational modeling of the design iterations, built prototypes, and tested their performance. The axial pump component was able to generate pressure rises of 1-112 mmHg for 2-5 L/min at 10,000-14,000 RPM, and the centrifugal pump component produced pressure rises of 1-184 mmHg for 2-5 L/min at 1750-3000 RPM. Shear stresses and blood damage estimations were less than 425 Pa and 0.5%, respectively. Axial and radial forces were also estimated to be less than 5 N for the axially and radially centered impellers. Data sets were repeatable, and data trends followed theoretical expectations. The new designs for the axial and centrifugal pumps enabled us to reduce the height of the pump while maintaining performance expectations. These findings support the continued development of this new medical device for pediatric patients. This article is protected by copyright. All rights reserved.</p>

DOI

10.1111/aor.13507

Alternate Title

Artif Organs

PMID

31162850

Title

Hybrid Continuous-Flow Total Artificial Heart.

Year of Publication

2018

Number of Pages

500-509

Date Published

2018 May

ISSN Number

1525-1594

Abstract

<p>Clinical studies using total artificial hearts (TAHs) have demonstrated that pediatric and adult patients derive quality-of-life benefits from this form of therapy. Two clinically-approved TAHs and other pumps under development, however, have design challenges and limitations, including thromboembolic events, neurologic impairment, infection risk due to large size and percutaneous drivelines, and lack of ambulation, to name a few. To address these limitations, we are developing a hybrid-design, continuous-flow, implantable or extracorporeal, magnetically-levitated TAH for pediatric and adult patients with heart failure. This TAH has only two moving parts: an axial impeller for the pulmonary circulation and a centrifugal impeller for the systemic circulation. This device will utilize the latest generation of magnetic bearing technology. Initial geometries were established using pump design equations, and computational modeling provided insight into pump performance. The designs were the basis for prototype manufacturing and hydraulic testing. The study results demonstrate that the TAH is capable of delivering target blood flow rates of 1-6.5 L/min with pressure rises of 1-92 mm Hg for the pulmonary circulation and 24-150 mm Hg for the systemic circulation at 1500-10&nbsp;000 rpm. This initial design of the TAH was successful and serves as the foundation to continue its development as a novel, more compact, nonthrombogenic, and effective therapeutic alternative for infants, children, adolescents, and adults with heart failure.</p>

DOI

10.1111/aor.13080

Alternate Title

Artif Organs

PMID

29349805

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