Competing Flow between Partial Circulatory Support and Native Cardiac Output: a computational Fluid Dynamics-Study

2016 ◽  
Vol 64 (S 01) ◽  
Author(s):  
J. Engelke ◽  
A.-F. Popov ◽  
S. Partovi ◽  
M. Karck ◽  
A. Simon ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cardiac Output ◽  
Circulatory Support

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.

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.

In-Silico Evaluation of Effects of Swirl Direction and Intensity on Aortic Flow Patterns Induced by an Aortic Pump Using Computational Fluid Dynamics

2014 ◽  
Author(s):  
Priti G. Albal ◽  
Prahlad G. Menon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Aortic Arch ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Patient Specific ◽  
Circulatory Support ◽  
Left Ventricular Assist Devices ◽  
Pump Design ◽  
Bridge To Transplant

Congestive heart failure has reached epidemic proportions in developed countries afflicting an estimated 23 million patients worldwide and more than 5.7 million patients suffering from it annually in USA. Left ventricular assist devices (LVADs) have gained acceptance for non-transplant NYHA Class III & IV HF patients to provide full or partial circulatory support as a bridge to transplant or destination therapy. Recently, investigators have suggested advantages of deploying a continuous flow pump within the aorta, through transcatheter deployment (eg: Abiomed Impella pump) and an anchoring device to lodge the pump across the diameter of the ascending aorta (AAo). In this study we evaluate feasibility of such a device anchored virtually at the AAo of a patient-specific aortic arch, using computational fluid dynamics (CFD). Constant inflow rate conditions of 0.7 m/s in the axial direction with varying swirl / tangential intensity at the AAo inlet (viz. pump outlet) was modeled simulative of a range of conditions affecting aortic helical grade (viz. secondary flow), using FLUENT 14.5 (ANSYS Inc.). A change of swirl intensity from +30% (right-handed, physiological) to −30% (left-handed) swirl led to increases in peak WSS (by 10.31%) and mean WSS (by 13.04%). This simulation based pilot study indicates that WSS in transverse aortic arch is a versatile indicator of non-physiological helical flow grade and may be a promising design parameter for hemodynamics-informed aortic pump design.

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.

Sign in / Sign up

Export Citation Format

Share Document