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).

Design Optimization of a Novel Polymeric Prosthetic Heart Valve and a Ventricular Assist Device via Device Thrombogenicity Emulation

2013 ◽  
Author(s):  
Thomas E. Claiborne ◽  
Wei-Che Chiu ◽  
Marvin J. Slepian ◽  
Danny Bluestein
Keyword(s):  
Heart Valves ◽  
Anticoagulation Therapy ◽  
Prosthetic Heart Valve ◽  
Total Artificial Heart ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Prosthetic Heart Valves ◽  
Ventricular Assist ◽  
Mechanical Circulatory Support Devices ◽  
Optimization Methodology

Thrombotic complications, such as hemorrhage or embolism, remain a major concern of blood contacting medical devices [1], including prosthetic heart valves (PHV) and mechanical circulatory support devices, e.g. ventricular assist devices (VAD) or the Total Artificial Heart (TAH) [2]. In most cases device recipients require life-long anticoagulation therapy, which increases the risk of hemorrhagic stroke and other bleeding disorders. In order to obviate the need for anticoagulants and reduce stroke risks, our group developed a unique optimization methodology, Device Thrombogenicity Emulation (DTE) [2–5]. With the DTE, the thrombogenic potential of a device is evaluated using extensive numerical modeling and calculating multiple platelet trajectories flowing through the device. The platelet stress-time waveforms are then emulated in our Hemodynamic Shearing Device (HSD) and their activation level is measured with our Platelet Activation State (PAS) assay. This provides a proxy validation of the simulation. We identify high shear stress producing regions within the device and modify its design to reduce or eliminate those potentially thrombogenic ‘hot-spots.’ Through an iterative process, we can optimize the device design prior to prototyping.

Design Optimization of a Mechanical Heart Valve for Reducing Valve Thrombogenicity: A Case Study With ATS Valve

2010 ◽  
Author(s):  
Gaurav Girdhar ◽  
Yared Alemu ◽  
Michalis Xenos ◽  
Jawaad Sheriff ◽  
Jolyon Jesty ◽  
...  
Keyword(s):  
Heart Valves ◽  
Thrombus Formation ◽  
Anticoagulation Therapy ◽  
Mechanical Heart Valve ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Ventricular Assist ◽  
Mechanical Circulatory Support Devices ◽  
Artificial Hearts

Flow past mechanical heart valves (MHV) in mechanical circulatory support devices including total artificial hearts and ventricular assist devices, is primarily implicated in thromboembolism due to non-physiological flow conditions where the elevated stresses and exposure times are sufficiently high to cause platelet activation and thrombus formation. Mitigation of this risk requires lifelong anticoagulation therapy and less thrombogenic MHV designs should therefore be developed by device manufacturers [1].

In-Vitro Thrombogenicity Assessment of Mechanical Circulatory Support Devices and Prosthetic Heart Valves

2010 ◽  
Author(s):  
Thomas E. Claiborne ◽  
Gaurav Girdhar ◽  
Jawaad Sheriff ◽  
Jolyon Jesty ◽  
Marvin J. Slepian ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Mechanical Circulatory Support ◽  
Heart Valves ◽  
Anticoagulation Therapy ◽  
Ventricular Assist Devices ◽  
Patient Specific ◽  
Circulatory Support ◽  
Prosthetic Heart Valves ◽  
Bridge To Transplant ◽  
Uncontrolled Bleeding

Mechanical circulatory support (MCS) devices developed for end-stage heart failure or as a bridge-to-transplant include total artificial hearts (TAH) and ventricular assist devices (VAD) and utilize prosthetic heart valves (PHV) or rotary impellers to control blood recirculation [1]. These devices are currently not optimized to reduce the incidence of pathological flow patterns that cause elevated stresses leading to platelet activation and thrombosis. Although the latter is partially mitigated by lifelong anticoagulation therapy, it dramatically increases the risk of uncontrolled bleeding. For instance thromboembolic stroke-related complications (∼2%) were relatively less with the TAH-t compared to uncontrolled bleeding due to anticoagulation use (∼20%) [2]. Platelet activation should therefore be quantified and optimized based on patient-specific cardiac outputs in device prototypes before clinical use.

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.

scholarly journals Driveline Infection in Ventricular Assist Devices and Its Implication in the Present Era of Destination Therapy

2017 ◽  
Vol 9 ◽  
pp. 117906521771421 ◽  
Author(s):  
Gabriel A Hernandez ◽  
Jonatan D Nunez Breton ◽  
Sandra V Chaparro
Keyword(s):  
Treatment Options ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Destination Therapy ◽  
Left Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Bridge To Transplant ◽  
Innovative Therapy

Advances in mechanical circulatory support devices provided the technology to develop long-term, implantable left ventricular assist devices as bridge to transplant, destination therapy, and in a lesser group of patients, as bridge to recovery. Despite the benefits from this innovative therapy, with their increased use, many complications have been encountered, one of the most common being infections. With the driveline acting as a portal to the exterior environment, an infection involving this structure is the most frequent one. Because patients with destination therapy are expected to receive circulatory support for a longer period of time, we will focus this review on the risk factors, prevention, and treatment options for driveline infections.

Evaluation of Platelet Activation Models With Dynamic Shear Stress In Vitro Experiments

2012 ◽  
Author(s):  
Jawaad Sheriff ◽  
Michalis Xenos ◽  
João S. Soares ◽  
Jolyon Jesty ◽  
Danny Bluestein
Keyword(s):  
Platelet Activation ◽  
Heart Valves ◽  
Ventricular Assist Devices ◽  
Prosthetic Heart Valves ◽  
Shear Stresses ◽  
Ventricular Assist ◽  
Relative Paucity ◽  
Valvular Diseases ◽  
End Stage

Blood recirculating devices, which include ventricular assist devices and prosthetic heart valves, are necessary for some patients suffering from end-stage heart failure and valvular diseases. However, disturbed flow patterns in these devices cause shear-induced platelet activation and aggregation. Thromboembolic complications resulting from this platelet behavior necessitates lifelong anticoagulant therapy for patients implanted with such devices. In addition, blood recirculating device manufacturers mostly test and optimize their products for hemolysis, which occurs at shear stresses ten-fold higher than required for platelet activation. The relative paucity of optimization for flow-induced thrombogenicity is further exacerbated by the fact that there are few predictive shear-induced platelet activation models.

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.

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].

Alternatives for Vitamin K Antagonists as Thromboprophylaxis for Mechanical Heart Valves and Mechanical Circulatory Support Devices: A Systematic Review

2021 ◽  
Author(s):  
Omayra C.D. Liesdek ◽  
Rolf T. Urbanus ◽  
Linda M. de Heer ◽  
Kathelijn Fischer ◽  
Willem J.L. Suyker ◽  
...  
Keyword(s):  
Vitamin K ◽  
Heart Valves ◽  
Vitamin K Antagonists ◽  
Anticoagulation Therapy ◽  
Left Ventricular ◽  
Mechanical Heart Valves ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Left Ventricular Assist Devices ◽  
Current Standard

AbstractThe holy grail of anticoagulation in patients with intracardiac devices, such as mechanical heart valves (MHVs) and left ventricular assist devices (LVADs), comprises safe prevention of thrombosis without interrupting normal hemostasis. Device-induced thrombosis and anticoagulant-related bleeding problems are dreaded complications that may cause a significantly reduced quality of life and increased morbidity and mortality. Vitamin K antagonists are the current standard for oral anticoagulation therapy in patients with MHVs and LVADs. Even within the therapeutic range, hemorrhage is the primary complication of these drugs, which emphasizes the need for safer anticoagulants for the prevention of device-induced thrombosis. Device-induced thrombosis is a complex multifactorial phenomenon that likely requires anticoagulant therapy targeting multiple pathways. Here, we review the preclinical and clinical data describing the efficacy of a variety of anticoagulants as thromboprophylaxis after implantation of intracardiac devices.

Cardiac transplantation and mechanical circulatory support

2020 ◽  
pp. 3428-3435
Author(s):  
Jayan Parameshwar ◽  
Steven Tsui
Keyword(s):  
Side Effects ◽  
Cardiac Transplantation ◽  
First Generation ◽  
Immunosuppressive Agents ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Blood Pumps ◽  
Rotary Blood Pumps

Cardiac transplantation is the treatment of choice for selected patients with advanced heart failure: median survival approaches 12 years and recipients enjoy an excellent quality of life, but availability is severely limited by shortage of donor organs. The need for lifelong immunosuppression is associated with side effects, including an increased incidence of malignancy. Newer immunosuppressive agents reduce nephrotoxicity and delay the onset of cardiac allograft vasculopathy, but may produce other side effects. Ventricular assist devices are mechanical blood pumps that work in parallel or series with the native ventricles. First-generation volume-displacement pulsatile ventricular assist devices have been superseded by rotary blood pumps that generate continuous flow. Significant complications include bleeding, thromboembolism, device failure due to pump thrombosis, and infection.

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