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].

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 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).

Anticoagulation Strategies for Patients on Mechanical Circulation Support

2019 ◽  
pp. 261-268
Author(s):  
Scott D. Nei
Keyword(s):  
Left Ventricular ◽  
Thrombin Inhibitors ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Factor X ◽  
Ventricular Assist ◽  
Mechanical Circulatory Support Devices ◽  
Artificial Hearts ◽  
Mechanical Circulation ◽  
New Research

Anticoagulation strategies for patients with mechanical circulatory support devices (MCSD) remain a daily challenge for clinicians. The balance between thrombosis and bleeding is delicate, with either extreme affecting patient morbidity and mortality. This chapter reviews the evidence for various anticoagulation strategies for patients with left ventricular assist devices (LVAD), extracorporeal membrane oxygenation (ECMO), and total artificial hearts (TAH). Clinical controversies related to tailoring anticoagulation strategies to individual patients addressed in this chapter include adjusting anticoagulation for gastrointestinal bleeding in patients with VADs and monitoring warfarin treatment with chromogenic factor X and with time in the therapeutic range. The direct use of thrombin inhibitors as primary anticoagulation for ECMO and the future of anticoagulation for MCSDs should help prepare clinicians for new research and changes in the field.

Development of Mechanical Circulatory Support Devices: 55 Years and Counting

2021 ◽  
Vol 32 (4) ◽  
pp. 424-433
Author(s):  
Emalie Petersen
Keyword(s):  
Mechanical Circulatory Support ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Left Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Left Ventricular Assist ◽  
Mechanical Circulatory Support Devices ◽  
Support Devices

Heart failure is a leading cause of morbidity and mortality in the United States. Treatment of this condition increasingly involves mechanical circulatory support devices. Even with optimal medical therapy and use of simple cardiac devices, heart failure often leads to reduced quality of life and a shortened life span, prompting exploration of more advanced treatment approaches. Left ventricular assist devices constitute an effective alternative to cardiac transplantation. These devices are not without complications, however, and their use requires careful cooperative management by the patient’s cardiology team and primary care provider. Left ventricular assist devices have undergone many technological advancements since they were first introduced, and they will continue to evolve. This article reviews the history of different types of left ventricular assist devices, appropriate patient selection, and common complications in order to increase health professionals’ familiarity with these treatment options.

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 Haemolysis induced by mechanical circulatory support devices: unsolved problems

Perfusion ◽  
2020 ◽  
Vol 35 (6) ◽  
pp. 474-483
Author(s):  
Inge Köhne
Keyword(s):  
Shear Stress ◽  
Continuous Flow ◽  
Mechanical Circulatory Support ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Ventricular Assist ◽  
Theoretical Approaches ◽  
Blood Pumps ◽  
Mechanical Circulatory Support Devices ◽  
Support Devices

Since the use of continuous flow blood pumps as ventricular assist devices is standard, the problems with haemolysis have increased. It is mainly induced by shear stress affecting the erythrocyte membrane. There are many investigations about haemolysis in laminar and turbulent blood flow. The results defined as threshold levels for the damage of erythrocytes depend on the exposure time of the shear stress, but they are very different, depending on the used experimental methods or the calculation strategy. Here, the results are resumed and shown in curves. Different models for the calculation of the strengths of erythrocytes are discussed. There are few results reported about tests of haemolysis in blood pumps, but some theoretical approaches for the design of continuous flow blood pumps according to low haemolysis have been investigated within the last years.

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.

Differences in Shear Stress, Residence Time and Estimates of Hemolysis Between Different Ventricular Assist Devices

2011 ◽  
Author(s):  
Katharine H. Fraser ◽  
Tao Zhang ◽  
Bartley P. Griffith ◽  
Zhongjun J. Wu
Keyword(s):  
Cardiovascular Disease ◽  
Mechanical Circulatory Support ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Ventricular Assist ◽  
The Past ◽  
The Us ◽  
Mechanical Circulatory Support Devices ◽  
End Stage ◽  
Support Devices

Cardiovascular disease is the leading cause of mortality globally. Among various forms of cardiovascular disease, heart failure (HF) affects 5.7 million patients in the United States1. Despite optimal treatment, some patients still do not improve and the available therapies fail to control their symptoms; for them, cardiac transplantation may be the only option. However, only around 2200 transplants are performed in the US each year1, or only about 6% of the estimated 35,000 US patients who would benefit actually receive a heart. To address the need to support the circulation in patients with end-stage HF a wide variety of mechanical circulatory support devices (MCSDs) have been developed over the past four decades.

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.

Comparative Studies of Axial Ventricular Assist Devices (VAD) and the Effect of Outflow Cannulation

2013 ◽  
Author(s):  
Wei-Che Chiu ◽  
Yared Alemu ◽  
Bryan Lynch ◽  
Shmuel Einav ◽  
Marvin Slepian ◽  
...  
Keyword(s):  
Heart Failure ◽  
The United States ◽  
Ventricular Assist Devices ◽  
Circulatory Support ◽  
Ventricular Assist ◽  
Assist Devices ◽  
High Incidence ◽  
Mechanical Circulatory Support Devices ◽  
Compact Design ◽  
Blood Flow Patterns

Congestive heart failure has reached epidemic proportions in the United States with more than 5.7 million patients suffering from it annually ( 1). Due to the limited availability of donor hearts, patients in their late stage heart failure who may require cardiac transplantation are dying while waiting for a matched heart. Mechanical circulatory support devices (MCS), such as ventricular assist devices (VAD), are utilized as a bridge to transplantation, and recently as destination therapy for extending the life of these patients. Continuous-flow VAD offer a surgical advantage over older generation pulsatile-flow VAD due to their compact design; however, due to the high RPM these VADs are operated with and the non-physiological blood flow patterns they generates, VADs are burdened with high incidence of thromboembolic events, and antiplatelet/anticoagulation regimens are mandated for the device recipients.

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