Verification of a Computational Cardiovascular System Model Comparing the Hemodynamics of a Continuous Flow to a Synchronous Valveless Pulsatile Flow Left Ventricular Assist Device

Gohean, Jeffrey R.; George, Mitchell J.; Pate, Thomas D.; Kurusz, Mark; Longoria, Raul G.; Smalling, Richard W.

doi:10.1097/mat.0b013e31827db6d4

Cited by 23 publications

(15 citation statements)

References 35 publications

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“…In previous investigations, however, some factors such as stroke volume (SV) and assist mode, 20,21 were not included, and only one aspect of blood damage was focused. Moreover, most of the investigational results were just qualitative.…”

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confidence: 99%

The Influence of Different Operating Conditions on the Blood Damage of a Pulsatile Ventricular Assist Device

et al. 2015

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Because of pulsatile blood flow's benefit for myocardial recovery, perfusion of coronary arteries and end organs, pulsatile ventricular assist devices (VADs) are still widely used as paracorporeal mechanical circulatory support devices in clinical applications, especially in pediatric heart failure patients. However, severe blood damage limits the VAD's service period. Besides optimizing the VAD geometry to reduce blood damage, the blood damage may also be decreased by changing the operating conditions. In this article, a pulsatile VAD was used to investigate the influence of operating conditions on its blood damage, including hemolysis, platelet activation, and platelet deposition. Three motion profiles of pusher plate (sine, cosine, and polynomial), three stroke volumes (ejection fractions) (56 ml [70%], 42 ml [52.5%], and 28 ml [35%]), three pulsatile rates (75, 100, and 150 bpm), and two assist modes (copulsation and counterpulsation) were implemented respectively in VAD fluid-structure interaction simulations to calculate blood damage. The blood damage indices indicate that cosine motion profile, higher ejection fraction, higher pulsatile rate, and counterpulsation can decrease platelet deposition whereas increase hemolysis and platelet activation, and vice versa. The results suggest that different operating conditions have different effects on pulsatile VAD's blood damage and may be beneficial to choose suitable operating condition to reduce blood damage in clinical applications.

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confidence: 99%

The Influence of Different Operating Conditions on the Blood Damage of a Pulsatile Ventricular Assist Device

et al. 2015

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“…This model has been validated with in vivo data (23, 24). The inputs to the model are patient size and HF severity, for which the stroke volume and synchronous operation of the TORVAD can be optimized.…”

Section: Design Resultsmentioning

confidence: 99%

Scaling the Low-Shear Pulsatile TORVAD for Pediatric Heart Failure

et al. 2017

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This article provides an overview of the design challenges associated with scaling the low-shear pulsatile TORVAD ventricular assist device (VAD) for treating pediatric heart failure. A cardiovascular system model was used to determine that a 15 ml stroke volume device with a maximum flow rate of 4 L/min can provide full support to pediatric patients with body surface areas between 0.6 to 1.5 m2. Low shear stress in the blood is preserved as the device is scaled down and remains at least two orders of magnitude less than continuous flow VADs. A new magnetic linkage coupling the rotor and piston has been optimized using a finite element model (FEM) resulting in increased heat transfer to the blood while reducing the overall size of TORVAD. Motor FEM has also been used to reduce motor size and improve motor efficiency and heat transfer. FEM analysis predicts no more than 1°C temperature rise on any blood or tissue contacting surface of the device. The iterative computational approach established provides a methodology for developing a TORVAD platform technology with various device sizes for supporting the circulation of infants to adults.

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“…A lumped-parameter model 31 of the cardiovascular system was used in this study. The model was a closed cardiovascular system loop and included elements that allowed assessment of the pressure and flow in the systemic and pulmonary arterial and venous systems as well as in the ventricles and atria.…”

Section: Methodsmentioning

confidence: 99%

“…The model was previously verified for comparing the hemodynamic effects of a CF VAD to the TORVAD™ using in vivo data. The details of this model have been previously reported, 31 so only a brief overview of the critical elements in the model is provided herein.…”

Section: Methodsmentioning

confidence: 99%

Preservation of Native Aortic Valve Flow and Full Hemodynamic Support with the TORVAD Using a Computational Model of the Cardiovascular System

et al. 2015

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This paper describes the stroke volume selection and operational design for the TORVAD™, a synchronous, positive-displacement ventricular assist device (VAD). A lumped parameter model was used to simulate hemodynamics with the TORVAD™ compared to those under continuous flow VAD support. Results from the simulation demonstrated that a TORVAD™ with a 30 mL stroke volume ejecting with an early diastolic counterpulse provides comparable systemic support to the HeartMate II® (HMII) (cardiac output 5.7 L/min up from 3.1 L/min in simulated heart failure). By taking advantage of synchronous pulsatility, the TORVAD™ delivers full hemodynamic support with nearly half the VAD flow rate (2.7 L/min compared to 5.3 L/min for the HMII) by allowing the left ventricle to eject during systole, thus preserving native aortic valve flow (3.0 L/min compared to 0.4 L/min for the HMII, down from 3.1 L/min at baseline). The TORVAD™ also preserves pulse pressure (26.7 mmHg compared to 12.8 mmHg for the HMII, down from 29.1 mmHg at baseline). Preservation of aortic valve flow with synchronous pulsatile support could reduce the high incidence of aortic insufficiency and valve cusp fusion reported in patients supported with continuous flow VADs.

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Verification of a Computational Cardiovascular System Model Comparing the Hemodynamics of a Continuous Flow to a Synchronous Valveless Pulsatile Flow Left Ventricular Assist Device

Cited by 23 publications

References 35 publications

The Influence of Different Operating Conditions on the Blood Damage of a Pulsatile Ventricular Assist Device

The Influence of Different Operating Conditions on the Blood Damage of a Pulsatile Ventricular Assist Device

Scaling the Low-Shear Pulsatile TORVAD for Pediatric Heart Failure

Preservation of Native Aortic Valve Flow and Full Hemodynamic Support with the TORVAD Using a Computational Model of the Cardiovascular System

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