Abstract 20526: Computational Fluid Dynamics in Partial Mechanical Circulatory Support: Implications for Patient Care

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Sasan Partovi ◽  
Christoph Karmonik ◽  
Fabian Rengier ◽  
Matthias Mueller-Eschner ◽  
Hagen Meredig ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Heart Failure ◽  
Computational Fluid Dynamics ◽  
Mechanical Circulatory Support ◽  
Cardiac Cycle ◽  
Heart Function ◽  
Innominate Artery ◽  
Flow Patterns ◽  
Flow Reversal ◽  
Circulatory Support

Introduction: Partial mechanical circulatory support (pMCS) is used for the therapy of heart failure. The CircuLite® Pump has been introduced clinically with its inflow cannula connected to the left atrium and the outflow cannula to the right subclavian artery. Aim of our study was to visualize and quantify flow patterns using computational fluid dynamics (CFD) in CT angiography (CTA). Methods: Two heart failure patients with pMCS were imaged with ECG-gated CTA and echocardiography. CFD was performed in 3D derived from CTA using flow boundary conditions measured with ultrasound. Flow was visualized using velocity vectors of blood flow. Average velocity was calculated at 10 time points during cardiac cycle in the aorta and the innominate. Wall shear stress (WSS) was visualized on the wall of the digital model. Results: Flow reversal was observed in mid-systole for both cases distal from the origin of the innominate artery in both cases due to asynchrony of the constant flow of the device with the pulsatile flow of the heart (fig.). Maximum velocity of this back flow was 0.39 m/s in case 1 and 0.2 m/s in case 2. Therefore, further distal in the innominate artery, a region of slow and stagnant flow with low WSS at the artery wall was observed which changed during cardiac cycle. Conclusions: CFD analysis revealed an asynchronous behavior in the inducted flow patterns during systole. Further design should allow for synchronization with the native heart function. Figure: On top flow during systole for both cases (case 1 on left), below flow during diastole. WSS is shown in pseudo-color representation with red indicating high values. Flow is visualized by arrows. During systole, a region of low WSS (blue) exists in the innominate artery which is absent during systole indicating flow reversal at this location. Bottom panel: Velocity in inferior-superior direction during cardiac cycle for both cases. Red lines demonstrates change of direction of flow in the innominate during systole.

Design of a Miniature Pump for Chronic Mechanical Circulatory Support Using Computational Fluid Dynamics and Flow Visualization

2017 ◽  
Author(s):  
J. Ryan Stanfield ◽  
Richard K. Wampler ◽  
Jingchun Wu ◽  
James Stewart ◽  
Trevor A. Snyder ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Heart Failure ◽  
Computational Fluid Dynamics ◽  
Flow Visualization ◽  
Mechanical Circulatory Support ◽  
Optical Measurement ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
End Stage Heart Failure ◽  
End Stage

Ventricular assist devices (VADs) have become an accepted method of treating end-stage heart failure over the last few decades. In recent years, the use of rotary blood pumps (RBPs) as continuous flow VADs has surged ahead, and virtually eliminated the use of pulsatile-flow or volume-displacement pumps for implantable, chronic mechanical circulatory support (MCS). As the use of RBPs has become commonplace for the treatment of end-stage heart failure, the need for an implantable right-side MCS device for adults [1] and implantable MCS for the pediatric population has increased. Development of an implantable device specific to these populations includes unique challenges of anatomic placement and fixation. Computational Fluid Dynamics (CFD) is the use of numerical methods and algorithms to solve and analyze problems involving fluid flow. CFD has become a standard tool when designing RBPs, as it can calculate pressure-flow characteristics for a given rotary impeller speed. Additionally, through calculation of shear forces, CFD can also predict hemocompatibility by means of constitutive equations derived from empirical data. Particle image velocimetry (PIV), also known as flow visualization, is an optical measurement technique used to obtain velocity in fluids, which can be employed experimentally to verify CFD-based predictions of flow field. PIV also permits more rapid investigation of the RBP operativing range and transient conditions than can be achieved with CFD due to computational requirements. We have developed a RBP platform for chronic use with CFD to optimize hemodynamic performance. The miniaturized device includes unique inlet geometry with a rotating impeller and a vaned-diffuser in a 7mm axial hydraulic diameter. The design scheme separates the bearing and motor region from the primary flow path to further improve hemocompatibility and reduce the pump size without compromising the hydraulic capacity. Here we report CFD and PIV results of our device geometry optimized for right-sided MCS.

Hemolysis associated with Impella heart pump positioning: In vitro hemolysis testing and computational fluid dynamics modeling

2020 ◽  
Vol 43 (11) ◽  
pp. 710-718
Author(s):  
Nicholas Roberts ◽  
Uma Chandrasekaran ◽  
Soumen Das ◽  
Zhongwei Qi ◽  
Scott Corbett
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mechanical Circulatory Support ◽  
Circulatory Support ◽  
Dynamics Modeling ◽  
Computational Fluid Dynamics Modeling ◽  
Heart Pump ◽  
Mechanical Circulatory Support Devices ◽  
Support Devices

Introduction: Short-term mechanical circulatory support devices provide temporary hemodynamic support in heart failure and are increasingly used to enable recovery or as a bridge to decision. Blood damage with mechanical circulatory support devices is influenced by many factors, including the magnitude and duration of shear stress and obstruction to blood flow. This study aimed to evaluate the effects of the Impella CP® heart pump positioning on hemolysis using in vitro hemolysis testing and computational fluid dynamics modeling. Methods: The in vitro hemolysis testing was conducted per the recommended Food and Drug Administration and American Society for Testing and Materials guidelines. The bench hemolysis testing and computational fluid dynamics simulation analysis were performed for both normal operating (outlet unobstructed) and outlet-obstructed condition of Impella CP (mimicking outlet on the aortic valve due to improper positioning). Results: The modified index of hemolysis was 2.78 ± 0.69 at normal operating conditions compared to 18.7 ± 7.8 when the Impella CP outlet was obstructed ( p = 0.002). Computational fluid dynamics modeling showed about three times increase in exposure time to regions of high shear stress when the Impella CP outlet was obstructed compared to unobstructed condition, thus supporting the experimental observations. Conclusion: Based on these results, it is recommended to ensure proper placement of Impella CP via regular monitoring using echocardiographic guidance or other methods to minimize the risk of hemolysis associated with an obstructed outflow.

Chronic Mechanical Circulatory Support for Patients with End-stage Heart Failure as a Definitive Treatment Option

2010 ◽  
Vol 6 (4) ◽  
pp. 22
Author(s):  
Patrycja Ganslmeier ◽  
Christof Schmid ◽  
◽  
Keyword(s):  
Heart Failure ◽  
Mechanical Circulatory Support ◽  
Definitive Treatment ◽  
Circulatory Support ◽  
Randomized Evaluation ◽  
Fda Approval ◽  
Cerebrovascular Events ◽  
Device Placement ◽  
End Stage Heart Failure ◽  
End Stage

Mechanical circulatory support for end-stage heart failure has become routine and is now increasingly used as definitive treatment. Several small devices qualify for this purpose, but only a few have gained US Food and Drug Administration (FDA) approval as yet. Several studies, including the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) study, the Investigation of Non-transplant-Eligible Patients Who Are Inotrope Dependent (INTrEPID) and the HeartMate (HM) II trial have confirmed a significantly improved quality of life and functional capacity after device placement. However, cerebrovascular events, infection and device malfunction still pose a considerable risk to patients and hinder widespread use.

Field testing CFD-based predictions of storage chamber gross solids separation efficiency

1999 ◽  
Vol 39 (9) ◽  
pp. 161-168 ◽  
Author(s):  
Virginia R. Stovin ◽  
Adrian J. Saul ◽  
Andrew Drinkwater ◽  
Ian Clifforde
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Settling Velocity ◽  
Separation Efficiency ◽  
Flow Patterns ◽  
Total Efficiency ◽  
Separation Performance ◽  
Storage Chamber ◽  
Solids Separation ◽  
Simulated Flow

The use of computational fluid dynamics-based techniques for predicting the gross solids and finely suspended solids separation performance of structures within urban drainage systems is becoming well established. This paper compares the result of simulated flow patterns and gross solids separation predictions with field measurements made in a full size storage chamber. The gross solids retention efficiency was measured for six different storage chambers in the field and simulations of these chambers were undertaken using the Fluent computational fluid dynamics software. Differences between the observed and simulated flow patterns are discussed. The simulated flow fields were used to estimate chamber efficiency using particle tracking. Efficiency results are presented as efficiency cusps, with efficiency plotted as a function of settling velocity. The cusp represents a range of efficiency values, and approaches to the estimation of an overall efficiency value from these cusps are briefly discussed. Estimates of total efficiency based on the observed settling velocity distribution differed from the measured values by an average of ±17%. However, estimates of steady flow efficiency were consistently higher than the observed values. The simulated efficiencies agreed with the field observations in identifying the most efficient configuration.

scholarly journals Pediatric Palliative Care in the Heart Failure, Ventricular Assist Device and Transplant Populations: Supporting Patients, Families and Their Clinical Teams

Children ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 468
Author(s):  
Kyle D. Hope ◽  
Priya N. Bhat ◽  
William J. Dreyer ◽  
Barbara A. Elias ◽  
Jaime L. Jump ◽  
...  
Keyword(s):  
Heart Failure ◽  
Palliative Care ◽  
Heart Transplantation ◽  
Ventricular Assist Device ◽  
Mechanical Circulatory Support ◽  
Pediatric Palliative Care ◽  
Circulatory Support ◽  
Assist Device ◽  
Ventricular Assist ◽  
Patients With Heart Failure

Heart failure is a life-changing diagnosis for a child and their family. Pediatric patients with heart failure experience significant morbidity and frequent hospitalizations, and many require advanced therapies such as mechanical circulatory support and/or heart transplantation. Pediatric palliative care is an integral resource for the care of patients with heart failure along its continuum. This includes support during the grief of a new diagnosis in a child critically ill with decompensated heart failure, discussion of goals of care and the complexities of mechanical circulatory support, the pensive wait for heart transplantation, and symptom management and psychosocial support throughout the journey. In this article, we discuss the scope of pediatric palliative care in the realm of pediatric heart failure, ventricular assist device (VAD) support, and heart transplantation. We review the limited, albeit growing, literature in this field, with an added focus on difficult conversation and decision support surrounding re-transplantation, HF in young adults with congenital heart disease, the possibility of destination therapy VAD, and the grimmest decision of VAD de-activation.

scholarly journals Can mechanical circulatory support be an effective treatment for HFpEF patients?

2021 ◽  
Author(s):  
Einar Gude ◽  
Arnt E. Fiane
Keyword(s):  
Heart Failure ◽  
Ejection Fraction ◽  
Mechanical Circulatory Support ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Left Ventricular Cavity ◽  
Circulatory Support ◽  
Left Ventricular Assist Devices ◽  
Mechanical Pressure ◽  
Entry Points

AbstractHeart failure with preserved ejection fraction (HFpEF) is increasing in prevalence and represents approximately 50% of all heart failure (HF) patients. Patients with this complex clinical scenario, characterized by high filling pressures, and reduced cardiac output (CO) associated with progressive multi-organ involvement, have so far not experienced any significant improvement in quality of life or survival with traditional HF treatment. Left ventricular assist devices (LVAD) have offered a new treatment alternative in terminal heart failure patients with reduced ejection fraction (HFrEF), providing a unique combination of significant pressure and volume unloading together with an increase in CO. The small left ventricular cavity in HFpEF patients challenges left-sided pressure unloading, and new anatomical entry points need to be explored for mechanical pressure and volume unloading. Optimized and pressure/volume-adjusted mechanical circulatory support (MCS) devices for HFrEF patients may conceivably be customized for HFpEF anatomy and hemodynamics. We have developed a long-term MCS device for HFpEF patients with atrial unloading in a pulsed algorithm, leading to a significant reduction of filling pressure, maintenance of pulse pressure, and increase in CO demonstrated in animal testing. In this article, we will discuss HFpEF pathology, hemodynamics, and the principles behind our novel MCS device that may improve symptoms and prognosis in HFpEF patients. Data from mock-loop hemolysis studies, acute, and chronic animal studies will be presented.

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