The 12cc Penn State Pulsatile Pediatric Ventricular Assist Device: Fluid Dynamics Associated With Valve Selection

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Benjamin T. Cooper ◽  
Breigh N. Roszelle ◽  
Tobias C. Long ◽  
Steven Deutsch ◽  
Keefe B. Manning
Keyword(s):  
Heart Valves ◽  
Flow Characteristics ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Bridge To Transplant ◽  
Recirculating Flow ◽  
Image Velocimetry ◽  
Penn State ◽  
Wall Shear ◽  
Pulsatile Vad

The mortality rate for infants awaiting a heart transplant is 40% because of the extremely limited number of donor organs. Ventricular assist devices (VADs), a common bridge-to-transplant solution in adults, are becoming a viable option for pediatric patients. A major obstacle faced by VAD designers is thromboembolism. Previous studies have shown that the interrelated flow characteristics necessary for the prevention of thrombosis in a pulsatile VAD are a strong inlet jet, a late diastolic recirculating flow, and a wall shear rate greater than 500s−1. Particle image velocimetry was used to compare the flow fields in the chamber of the 12cc Penn State pediatric pulsatile VAD using two mechanical heart valves: Björk–Shiley monostrut (BSM) tilting disk valves and CarboMedics (CM) bileaflet valves. In conjunction with the flow evaluation, wall shear data were calculated and analyzed to help quantify wall washing. The major orifice inlet jet of the device containing BSM valves was more intense, which led to better recirculation and wall washing than the three jets produced by the CM valves. Regurgitation through the CM valve served as a significant hindrance to the development of the rotational flow.

A Fluid Dynamics Study Focusing on Wall Shear Rates Within the Penn State 12 cc Pulsatile Pediatric Ventricular Assist Device: A Comparison of Mechanical Heart Valve Types

2007 ◽  
Author(s):  
Benjamin T. Cooper ◽  
Breigh N. Roszelle ◽  
Tobias C. Long ◽  
Steven Deutsch ◽  
Keefe B. Manning
Keyword(s):  
Ventricular Assist Device ◽  
Mechanical Heart Valve ◽  
Flow Characteristics ◽  
Assist Device ◽  
Ventricular Assist ◽  
Recirculating Flow ◽  
Image Velocimetry ◽  
Penn State ◽  
Wall Shear ◽  
Pulsatile Vad

Previous studies have shown that the interrelated flow characteristics necessary for the prevention of thrombosis in a pulsatile ventricular assist device (VAD) are a strong inlet jet, a late diastolic recirculating flow, and adequate wall washing (greater than 500 s−1). Particle image velocimetry was used to compare the flow fields in the chamber of the 12 cc Penn State pediatric pulsatile VAD using two valves: Björk-Shiley Monostrut (BSM) tilting-disc valves at the inlet and outlet and Carbomedics (CM) bi-leaflet valves at the inlet and outlet. In conjunction with the flow evaluation, wall shear data were calculated and analyzed to help to quantify wall washing. The major orifice inlet jet of the device containing BSM valves was more intense which led to better circulation and wall washing than the three jets produced by the CM valves Regurgitation through the CM valve was observed and served as a significant hindrance to the development of the rotational flow.

Impact of Outlet Valve Orientation on Fluid Dynamics of the 12 cc Penn State Pediatric Ventricular Assist Device

2008 ◽  
Author(s):  
Isabella E. Valenti ◽  
Breigh N. Roszelle ◽  
Michael V. Perone ◽  
Steven Deutsch ◽  
Keefe B. Manning
Keyword(s):  
Heart Valves ◽  
Thrombus Formation ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Bridge To Transplant ◽  
Penn State ◽  
Outlet Valve ◽  
Cardiovascular Defects ◽  
Interior Walls ◽  
Arteries And Veins

Congenital cardiovascular defects are the leading cause of death among live births [1]. These defects involve the interior walls of the heart, valves, arteries, and veins and change the normal flow of blood through the heart and into the systemic system. Fortunately, several options exist for the more than 35,000 children born with congenital heart disease. Ventricular assist devices (VADs) currently hold the most promise for bridge-to-transplant treatment; however, a major problem for these devices is thrombus formation and deposition.

Using Animal Models to Study Pediatric Cardiovascular Devices: The Impact on Fluid Dynamics

2008 ◽  
Author(s):  
Tobias C. Long ◽  
Michael V. Perone ◽  
Steven Deutsch ◽  
Keefe B. Manning
Keyword(s):  
Fluid Dynamics ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Cardiovascular Devices ◽  
Bridge To Transplant ◽  
Period 2 ◽  
Image Velocimetry ◽  
Pulsatile Vad ◽  
End Stage ◽  
The Impact

Due to a high mortality rate for pediatric patients on the heart transplant list, smaller versions of ventricular assist devices (VADs) are being developed for these patients [1]. Ventricular assist devicess used in adult patients with end-stage heart failure have already become a viable option during the bridge-to-transplant period [2] and have also shown potential for aiding in myocardial recovery. A challenge to the development of pediatric VADs is the use of the aortic cannulae attached to them. During the development of the 12cc Pennsylvania State pediatric pulsatile VAD, particle image velocimetry (PIV) illustrated that hematocrit levels affected the fluid dynamics. The objective of this study is to compare the fluid dynamics of a pediatric blood analog and a goat blood analog within PVAD aortic cannulae.

Experimental Wall Shear Estimation as a Means of Predicting Thrombus Formation Within a 50cc Penn State Blood Pump

2010 ◽  
Author(s):  
Jason C. Nanna ◽  
Stephen R. Topper ◽  
Ning Yang ◽  
Breigh N. Roszelle ◽  
Steven Deutsch ◽  
...  
Keyword(s):  
Heart Function ◽  
Thrombus Formation ◽  
Flow Characteristics ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Shear Rates ◽  
Penn State ◽  
Wall Shear ◽  
The 1960S ◽  
Flow Stasis

The use of ventricular assist devices (VADs) as a means of cardiac support for patients with diminished heart function has been investigated since the 1960s [1]. While VAD therapy has had success in assisting the failing heart, thrombus formation within these devices is one of various complications that still limit its long term use. Research has shown that thrombus deposition in VADs is a function of the underlying fluid mechanics within these devices. Areas of flow stasis, high blood residence time, and wall shear rates under 500 s−1 are important flow characteristics driving thrombosis [2].

Design Optimization of Rotary Blood Pumps: Alternatives to Anticoagulation Therapy

2011 ◽  
Author(s):  
Gaurav Girdhar ◽  
Michalis Xenos ◽  
Wei-Che Chiu ◽  
Yared Alemu ◽  
Bryan Lynch ◽  
...  
Keyword(s):  
Heart Valves ◽  
Anticoagulation Therapy ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Shear Stresses ◽  
Ventricular Assist ◽  
Bridge To Transplant ◽  
Life Saving ◽  
Optimization Methodology ◽  
Rotary Blood Pumps

Mechanical circulatory support (MCS) devices such as the ventricular assist devices (VADs) provide life saving short-term bridge-to-transplant solutions (1) to a large proportion of patients who suffer from chronic heart failure. Although hemodynamically efficient, such devices are burdened with high incidence of thromboembolic events due to non-physiological flow past constricted geometries where platelets (the principal cellular clotting elements in blood) are exposed to elevated shear stresses and exposure times (2) — requiring mandatory anticoagulation. We recently developed an optimization methodology — Device Thrombogenicity Emulator (DTE)(3) — that integrates device specific hemodynamic stresses (from numerical simulations) with experimental measurements of platelet activation. The DTE was successfully applied by our group to measure / optimize the thromboresistance of mechanical heart valves (MHV) (3, 4).

Dynamic Shear Stress Induced Platelet Activation in Blood Recirculation Devices: Implications for Thrombogenicity Minimization

2009 ◽  
Author(s):  
Gaurav Girdhar ◽  
Jawaad Sheriff ◽  
Michalis Xenos ◽  
Yared Alemu ◽  
Thomas Claiborne ◽  
...  
Keyword(s):  
Shear Stress ◽  
Platelet Activation ◽  
Heart Valves ◽  
Total Artificial Heart ◽  
Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Bridge To Transplant ◽  
End Stage ◽  
Effective Design

Implantable blood recirculation devices such as ventricular assist devices (VADs) and more recently the temporary total artificial heart (TAH-t) are promising bridge-to-transplant (BTT) solutions for patients with end-stage cardiovascular disease. However, blood flow in and around certain non-physiological geometries, mostly associated with pathological flow around mechanical heart valves (MHVs) of these devices, enhances shear stress-induced platelet activation, thereby significantly promoting flow induced thrombogenicity and subsequent complications such as stroke, despite a regimen of post-implant antithrombotic agents. Careful characterization of such localized high shear stress trajectories in these devices by numerical techniques and corresponding experimental measurements of their accentuated effects on platelet activation and sensitization, is therefore critical for effective design optimization of these devices (reducing the occurrence of pathological flow patterns formation) for minimizing thrombogenicity [1].

A Particle Image Velocimetry Study of the Penn State 50cc Left Ventricular Assist Device: The Impact of Varying Heart Rate

2011 ◽  
Author(s):  
Michael A. Navitsky ◽  
Jason C. Nanna ◽  
Stephen R. Topper ◽  
Steven Deutsch ◽  
Keefe B. Manning
Keyword(s):  
Heart Failure ◽  
Thrombus Formation ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Left Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Bridge To Transplant ◽  
Left Ventricular Assist ◽  
Penn State ◽  
The Impact

Approximately 5.7 million Americans are afflicted with heart failure, with a reported 670,000 new diagnoses each year [1]. Left ventricular assist devices (LVADs) function as a bridge to transplant therapy for advanced staged heart failure patients awaiting a donor heart. A pulsatile 50cc LVAD, Figure 1, is currently under development for cardiac support of patients with limited chest cavity size. Although the 50cc LVAD is functional in assisting a failing ventricle, complications such as thrombus formation may limit long term usage.

A Correlative Study of Fluid Mechanics and Evidence of Thrombus Formation Within the Penn State 50 CC Left Ventricular Assist Device

2012 ◽  
Author(s):  
Stephen R. Topper ◽  
Michael A. Navitsky ◽  
Christopher A. Siedlecki ◽  
Steven Deutsch ◽  
Gerson Rosenberg ◽  
...  
Keyword(s):  
Thrombus Formation ◽  
Major Complication ◽  
The United States ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Heart Transplants ◽  
Ventricular Assist ◽  
Bridge To Transplant ◽  
Left Ventricular Assist ◽  
Penn State

An estimated 82.6 million American adults live with one or more forms of cardiovascular disease and in past years, it was the cause of over 55% of all deaths in the United States, more than any other type of major disease [1]. With a limited number of available donors, heart transplants are seldom an option. As a result, ventricular assist devices (VADs) have become a viable alternative to immediate transplant. Today, VADs are widely used as bridge-to-recovery, bridge-to-transplant and destination therapy devices. Despite past improvements in VAD design, a major complication that continues to arise is thrombus formation within the pump.

scholarly journals Methods for determination of stagnation in pneumatic ventricular assist devices

2018 ◽  
Vol 41 (10) ◽  
pp. 653-663 ◽  
Author(s):  
Damian Obidowski ◽  
Piotr Reorowicz ◽  
Dariusz Witkowski ◽  
Krzysztof Sobczak ◽  
Krzysztof Jóźwik
Keyword(s):  
Particle Image Velocimetry ◽  
Ventricular Assist Device ◽  
Particle Image ◽  
Single Case ◽  
Ventricular Assist Devices ◽  
Assist Device ◽  
Single Experiment ◽  
Ventricular Assist ◽  
University Of Technology ◽  
Image Velocimetry

Background: A pneumatic paediatric ventricular assist device developed at the Foundation of Cardiac Surgery Development, Zabrze, equipped with valves based on J. Moll’s design, with later modifications introduced at the Institute of Turbomachinery, Lodz University of Technology, was tested numerically and experimentally. The main aim of those investigations was to detect stagnation zones within the ventricular assist device and indicate advantages and limitations of both approaches. Methods: In the numerical transient test, a motion of the diaphragm and discs was simulated. Two different methods were used to illustrate stagnation zones in the ventricular assist device. The flow pattern inside the chamber was represented by velocity contours and vectors to validate the results using images obtained in the laser particle image velocimetry experiment. Results: The experimental light-based method implied problems with proper illumination of regions in the wall vicinity. High-resolution flow data and other important parameters as stagnation regions or flow patterns in regions not accessible for light in the particle image velocimetry method are derived in the numerical solution. However, computations of a single case are much more time-consuming if compared to a single experiment conducted on a well-calibrated stand. Conclusion: The resulting main vortexes in the central part of the pump chamber and the velocity magnitudes are correlated in both methods, which are complementary and when used together offer better insight into the flow structure inside the ventricular assist device and enable a deeper analysis of the results.

High-frequency operation of pulsatile ventricular assist devices: A computational study on circular and elliptically shaped pumps

2019 ◽  
Vol 42 (12) ◽  
pp. 725-734 ◽  
Author(s):  
Christian Loosli ◽  
Stephan Rupp ◽  
Bente Thamsen ◽  
Mathias Rebholz ◽  
Gerald Kress ◽  
...  
Keyword(s):  
High Frequency ◽  
Flow Patterns ◽  
Ventricular Assist Devices ◽  
Shear Stresses ◽  
Residence Times ◽  
Pump Frequency ◽  
Ventricular Assist ◽  
Assist Devices ◽  
High Frequency Operation ◽  
Wall Shear

Pulsatile positive displacement pumps as ventricular assist devices were gradually replaced by rotary devices due to their large volume and high adverse event rates. Nevertheless, pulsatile ventricular assist devices might be beneficial with regard to gastrointestinal bleeding and cardiac recovery. Therefore, aim of this study was to investigate the flow field in new pulsatile ventricular assist devices concepts with an increased pump frequency, which would allow lower stroke volumes to reduce the pump size. We developed a novel elliptically shaped pulsatile ventricular assist devices, which we compared to a design based on a circular shape. The pump size was adjusted to deliver similar flow rates at pump frequencies of 80, 160, and 240 bpm. Through a computational fluid dynamics study, we investigated flow patterns, residence times, and wall shear stresses for different frequencies and pump sizes. A pump size reduction by almost 50% is possible when using a threefold pump frequency. We show that flow patterns inside the circular pump are frequency dependent, while they remain similar for the elliptic pump. With slightly increased wall shear stresses for higher frequencies, maximum wall shear stresses on the pump housing are higher for the circular design (42.2 Pa vs 18.4 Pa). The calculated blood residence times within the pump decrease significantly with increasing pump rates. A smaller pump size leads to a slight increase of wall shear stresses and a significant improvement of residence times. Hence, high-frequency operation of pulsatile ventricular assist devices, especially in combination with an elliptical shape, might be a feasible mean to reduce the size, without any expectable disadvantages in terms of hemocompatibility.

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