The development of control techniques for ventricular-assist devices and a hierarchical control structure to regulate the operation of a turbo-hydrodynamic assist device - Hierarchical control of heart-assist devices

Introduction: Despite significant technical advancements in the design and manufacture of Left Ventricular Assist Devices, post-implant thrombotic and thromboembolic complications continue to affect long-term outcomes. Previous efforts, aimed at optimizing pump design as a means of reducing supraphysiologic shear stresses generated within the pump and associated prothrombotic shear-mediated platelet injury, have only partially altered the device hemocompatibility. Methods: We examined hemodynamic mechanisms that synergize with hypershear within the pump to contribute to the thrombogenic potential of the overall Left Ventricular Assist Device system. Results: Numerical simulations of blood flow in differing regions of the Left Ventricular Assist Device system, that is the diseased native left ventricle, the pump inflow cannula, the impeller, the outflow graft and the anastomosed downstream aorta, reveal that prothrombotic hemodynamic conditions might occur at these specific sites. Furthermore, we show that beyond hypershear, additional hemodynamic abnormalities exist within the pump, which may elicit platelet activation, such as recirculation zones and stagnant platelet trajectories. We also provide evidences that particular Left Ventricular Assist Device implantation configurations and specific post-implant patient management strategies, such as those allowing aortic valve opening, are more hemodynamically favorable and reduce the thrombotic risk. Conclusion: We extend the perspective of pump thrombosis secondary to the supraphysiologic shear stress environment of the pump to one of Left Ventricular Assist Device system thrombosis, raising the importance of comprehensive characterization of the different prothrombotic risk factors of the total system as the target to achieve enhanced hemocompatibility and improved clinical outcomes.

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1180. Colonization with Multidrug-Resistant Organisms Is Associated with Subsequent Infection in the Ventricular Assist Device Population

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.1043 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S423-S423

Author(s):

Scott C Roberts ◽

Jonathan D Rich ◽

Duc T Pham ◽

Rebecca Harap ◽

Valentina Stosor

Keyword(s):

Ventricular Assist Device ◽

Retrospective Cohort ◽

Multidrug Resistant ◽

Ventricular Assist Devices ◽

Resistant Organism ◽

Subsequent Infection ◽

Assist Device ◽

Ventricular Assist ◽

Assist Devices ◽

Multidrug Resistant Organisms

Abstract Background Infection is a leading cause of morbidity and mortality in the ventricular assist device (VAD) population. We performed a retrospective cohort study outlining the epidemiology of multidrug-resistant organism (MDRO) colonization and infection rates in this population. Methods We performed a longitudinal retrospective cohort of all patients receiving continuous-flow (axial and centrifugal) ventricular assist devices from July 2008 to September 2018 at Northwestern Memorial Hospital. Peri-operative prophylaxis from July 2008 to June 2013 was vancomycin, rifampin, ciprofloxacin, and fluconazole, and vancomycin plus cefuroxime from June 2013 to September 2018. VAD-specific and VAD-related Infections were classified according to ISHLT 2013 definitions. Patients were screened for methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis or Enterococcus faecium, or extended-spectrum β-lactamase producing Gram-negative rods. Statistics were performed using IBM® SPSS Statistics version 25.0. Comparative statistics were performed using two-sided Fisher’s exact test with a P-value of <0.05 deemed significant. Results A total of 89 patients with ventricular assist devices developed either VAD-specific or VAD-related infections and were included in the analysis. 77% of patients (n = 66) were colonized with an MDRO; 29% (n = 25) with MRSA, 73% (n = 63) with VRE, and 24% (n = 21) with an ESBL organism. 17.9% (n = 16) of patients who went on to develop infection was secondary to MDROs. Colonization with an MDRO was associated with subsequent infection secondary to these organisms (P = 0.018). Conclusion Colonization rates of multidrug-resistant organisms in the VAD population are high. VRE rates were significantly higher than MRSA or ESBL, possible as a result of peri-implantation utilization of vancomycin as surgical site prophylaxis. MDRO colonization was associated with progression to VAD-specific or VAD-related Infection. Disclosures All authors: No reported disclosures.

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Automatic control of dual left ventricular assist devices as a biventricular assist device

10.14264/uql.2015.136 ◽

2014 ◽

Author(s):

Michael Stevens

Keyword(s):

Automatic Control ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Left Ventricular Assist Devices ◽

Assist Device ◽

Ventricular Assist ◽

Assist Devices ◽

Biventricular Assist Device ◽

Left Ventricular Assist

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Outcome for children following admission to hospital with a first episode of heart failure, due to heart muscle disease, in the ventricular assist device (VAD) era

Cardiology in the Young ◽

10.1017/s1047951119001021 ◽

2019 ◽

Vol 29 (7) ◽

pp. 888-892

Author(s):

Andres Rico-Armada ◽

David S. Crossland ◽

Louise Coats ◽

Zdenka Reinhardt ◽

Anthony Hermuzi ◽

...

Keyword(s):

Heart Failure ◽

Heart Muscle ◽

Recovery Of Function ◽

Muscle Disease ◽

Ventricular Assist Devices ◽

Circulatory Support ◽

First Episode ◽

Assist Device ◽

Ventricular Assist ◽

Assist Devices

AbstractAims:Most reports on the outcome of children who present with heart failure, due to heart muscle disease, are from an era when ventricular assist devices were not available. This study provides outcome data for the current era where prolonged circulatory support can be considered for most children.Methods & Results:Data was retrieved on 100 consecutive children, who presented between 2010 – 2016, with a first diagnosis of unexplained heart failure. Hospital outcome was classified as either death, transplantation, recovery of function or persistent heart failure. Median age at presentation was 24 months and 58% were < 5 years old. Hospital mortality was 12% and 59% received a heart transplant. Most, 79%, of the transplants were carried out on patients with a device. Recovery of function was observed in 18% and 10% stabilised on oral therapy. Eighty-four percent of the deaths occurred in the <5 year old group. Shorter duration of support was associated with survival (34 days in survivors versus 106 in non-survivors, p = 0.01) and 72% were on an assist device at time of death.Conclusion:Heart failure in children who require referral to a transplant unit is a serious illness with a high chance of either transplantation or death. Modifications in assist devices will be required to improve safety, especially for children < 5 years old where the donor wait may be prolonged. The identification of children who may recover function requires further study.

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Poor outcomes resulting from ventricular assist devices implanted in hospitals without dedicated ventricular assist device programs

Mechanical Circulatory Support ◽

10.3402/mcs.v2i0.5974 ◽

2011 ◽

Vol 2 (1) ◽

pp. 11826574 ◽

Cited By ~ 1

Author(s):

Anelechi C. Anyanwu ◽

Sean Pinney ◽

Kimmarie Hammond ◽

Kimberly Ashley ◽

David H. Adams

Keyword(s):

Ventricular Assist Device ◽

Ventricular Assist Devices ◽

Assist Device ◽

Ventricular Assist ◽

Assist Devices ◽

Poor Outcomes

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Extended right posterior liver sectionectomy for HCC in a patient with left ventricular assist device—a case report

Journal of Surgical Case Reports ◽

10.1093/jscr/rjaa307 ◽

2020 ◽

Vol 2020 (9) ◽

Author(s):

Lea Timmermann ◽

Moritz Schmelzle ◽

Evgenij Potapov ◽

Marcus Müller ◽

Christian Lojewski ◽

...

Keyword(s):

Case Report ◽

Left Ventricular Assist Device ◽

Ventricular Assist Device ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Left Ventricular Assist Devices ◽

Assist Device ◽

Ventricular Assist ◽

Assist Devices ◽

Left Ventricular Assist

Abstract Successful implementation of left ventricular assist devices lead to a prolonged survival in patients with chronic terminal heart failure. Thus, patients with pre-existing left ventricular assist devices with abdominal comorbidities requiring abdominal surgery, e.g. for malignancy, are upcoming issues. We carried out a major liver resection for hepatocellular carcinoma in a patient with pre-existing left ventricular assist device. The importance of this case report is that it outlines the significance of oncologic resections in patients with left ventricular assist devices as an upcoming issue and provides an interdisciplinary approach.

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Endovascular treatment of stroke in children under 2 years with heart failure and ventricular assist device

Interventional Neuroradiology ◽

10.1177/1591019919844946 ◽

2019 ◽

Vol 25 (5) ◽

pp. 516-520

Author(s):

Elvira Jiménez Gómez ◽

Isabel Bravo Rey ◽

Rafael Oteros Fernández ◽

Fernando Delgado Acosta

Keyword(s):

Endovascular Treatment ◽

Left Hemisphere ◽

Ventricular Assist Device ◽

Clinical Results ◽

Ventricular Assist Devices ◽

Cardiac Transplant ◽

Assist Device ◽

Ventricular Assist ◽

Assist Devices ◽

Left Hemisphere Stroke

Introduction Strokes in children are characterised by a high mortality rate while, at the same time, the low number of cases makes it difficult to gain practical experience. As heart disease is the most common risk factor, and as more and more cardiological interventions are being carried out, an increase in the incidence of paediatric stroke is expected. In some cases a transplant is required. While waiting for a donor, the use of ventricular assist devices may be necessary. These present with a high rate of neurological complications. We present two cases of children under 2 years of age awaiting heart transplantation supported by ventricular assist devices who had a stroke which was treated by endovascular techniques. Case 1: A 16-month-old boy with restrictive cardiomyopathy who was listed for a cardiac transplant. At 20 months he required an implantation of an external biventricular support device (Berlin Heart) and had a left hemisphere stroke at 23 months. An intra-arterial approach was used and produced good clinical results. One month later, a heart transplant was performed successfully. Case 2: An 18-month-old girl with non-compacted dilated cardiomyopathy included in the cardiac transplant programme and in need of a Levitronix Centrimag ventricular assist device presented with an acute left hemisphere stroke at 23 months. An intra-arterial procedure was carried out leading to positive clinical results except for residual right hypertonia. Seven months later she received her transplant. Conclusion As a result of the difficulty in performing arterial puncture, the small vessel calibre and the limitation in the use of iodated contrast, there are certain limitations to endovascular treatment of strokes in children that can lead to complications. A multidisciplinary approach to managing such cases would be helpful.

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In-Vitro Biocompatibility and Hemocompatibility Study of New PET Copolyesters Intended for Heart Assist Devices

Polymers ◽

10.3390/polym12122857 ◽

2020 ◽

Vol 12 (12) ◽

pp. 2857

Author(s):

Maciej Gawlikowski ◽

Miroslawa El Fray ◽

Karolina Janiczak ◽

Barbara Zawidlak-Węgrzyńska ◽

Roman Kustosz

Keyword(s):

Biological Properties ◽

Ventricular Assist Devices ◽

Ventricular Assist ◽

Assist Devices ◽

Good Thermal Stability ◽

In Vitro Biocompatibility ◽

Heart Assist Devices ◽

Poly Ethylene ◽

Medical Grade

(1) Background: The evaluation of ventricular assist devices requires the usage of biocompatible and chemically stable materials. The commonly used polyurethanes are characterized by versatile properties making them well suited for heart prostheses applications, but simultaneously they show low stability in biological environments. (2) Methods: An innovative material-copolymer of poly(ethylene-terephthalate) and dimer linoleic acid—with controlled and reproducible physico-mechanical and biological properties was developed for medical applications. Biocompatibility (cytotoxicity, surface thrombogenicity, hemolysis, and biodegradation) were evaluated. All results were compared to medical grade polyurethane currently used in the extracorporeal heart prostheses. (3) Results: No cytotoxicity was observed and no significant decrease of cells density as well as no cells growth reduction was noticed. Thrombogenicity analysis showed that the investigated copolymers have the thrombogenicity potential similar to medical grade polyurethane. No hemolysis was observed (the hemolytic index was under 2% according to ASTM 756-00 standard). These new materials revealed excellent chemical stability in simulated body fluid during 180 days aging. (4) Conclusions: The biodegradation analysis showed no changes in chemical structure, molecular weight distribution, good thermal stability, and no changes in surface morphology. Investigated copolymers revealed excellent biocompatibility and great potential as materials for blood contacting devices.

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Computational characterization of flow and blood damage potential of the new maglev CH-VAD pump versus the HVAD and HeartMate II pumps

The International Journal of Artificial Organs ◽

10.1177/0391398820903734 ◽

2020 ◽

Vol 43 (10) ◽

pp. 653-662 ◽

Cited By ~ 1

Author(s):

Jiafeng Zhang ◽

Zengsheng Chen ◽

Bartley P Griffith ◽

Zhongjun J Wu

Keyword(s):

Fluid Dynamics ◽

Shear Stress ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Left Ventricular Assist Devices ◽

Assist Device ◽

Heartmate Ii ◽

Ventricular Assist ◽

Assist Devices ◽

Left Ventricular Assist

Left ventricular assist devices are routinely used to treat patients with advanced heart failure as a bridge to transplant or a destination therapy. However, non-physiological shear stress generated by left ventricular assist devices damages blood cells. The continued development of novel left ventricular assist devices is essential to improve the left ventricular assist device therapy for heart failure patients. The CH-VAD is a new maglev centrifugal left ventricular assist device. In this study, the CH-VAD pump was numerically analyzed and compared with the HVAD and HeartMate II pumps under two clinically relevant conditions (flow: 4.5 L/min, pressure head: normal ~80 and hypertension ~120 mmHg). The velocity and shear stress fields, washout, and hemolysis index of the three pumps were assessed with computational fluid dynamics analysis. Under the same condition, the CH-VAD hemolysis index was two times lower than the HVAD and HeartMate II pumps; the CH-VAD had the least percentage volume with shear stress larger than 100 Pa (i.e. normal condition: 0.4% vs HVAD 1.0%, and HeartMate II 2.9%). Under the normal condition, more than 98% was washed out of the three pumps within 0.4 s. The washout times were slightly shorter under the hypertension condition for the three pumps. No regions inside the CH-VAD or HVAD had extremely long residential time, while areas near the straightener of the HeartMate II pump had long residential time (>4 s) indicating elevated risks of thrombosis. The computational fluid dynamics results suggested that the CH-VAD pump has a better hemolytic biocompatibility than the HVAD and HeartMate II pumps under the normal and hypertension conditions.

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Prerequisites to Salvage Profound Biventricular Failure Patients with Ventricular Assist Devices

The International Journal of Artificial Organs ◽

10.1177/039139888901200406 ◽

1989 ◽

Vol 12 (4) ◽

pp. 234-241 ◽

Cited By ~ 1

Author(s):

T. Nakatani ◽

H. Takano ◽

H. Noda ◽

Y. Taenaka ◽

M. Umezu ◽

...

Keyword(s):

Myocardial Damage ◽

Left Ventricular ◽

Acute Stage ◽

Ventricular Assist Devices ◽

Right Atrial ◽

Assist Device ◽

Ventricular Assist ◽

Assist Devices ◽

Biventricular Failure ◽

The Right

We conducted chronic experiments to determine how to treat profound biventricular failure systematically with ventricular assist devices (VADs) and to analyze the factors that affect prognoses for this condition. Anoxic arrest was induced in ten goats by aortic cross-clamping under normothermic conditions (38.5° C) for 30 (n= 3), 45 (n= 1), and 60 (n= 6) minutes. A left ventricular assist device (LVAD) was implanted in eight animals, and a biventricular assist device (BVAD) was used in two. Three goats — two of which had undergone anoxic arrest for 30 minutes and one for 60 minutes — whose right atrial pressure (RAP) was approximately 18 mm Hg during the acute stage, recovered in two to three weeks, and the pumps were successfully removed. Pathological findings in these animals showed scattered areas of surviving myocardium, with connective tissue replacing the degenerated myocardium. The remaining five LVAD goats required higher RAPs to maintain circulation and died from various causes. Maintaining circulation without volume loading, even in the presence of arrhythmias, was easier with the BVAD. One BVAD animal that underwent 45 minutes of anoxic arrest recovered from right ventricular failure, and the right pump was removed. The second goat (anoxic arrest, 60 min) on the BVAD failed to recover. Autopsy of the myocardium revealed a thin ventricular wall. Our studies show that the use of VADs allows time for a failing heart to recover, but the potential for healing is affected by the severity of myocardial damage prior to VAD application. We believe that although LVADs can maintain circulation with high RAPs, the use of BVADs might be more beneficial for maintaining systemic organ function in cases of persistent biventricular failure.

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