Measuring real-time blood viscosity with a ventricular assist device

Ventricular assist devices assist in blood circulation and form a crucial component of artificial hearts. While it is important to measure parameters such as the flow rate, pressure head and viscosity of the blood, implanting additional devices to do such measurements is inadvisable. To this end, we demonstrate the adaptation of a ventricular assist device for the purpose of measuring blood viscosity. Such an approach eliminates the need for additional dedicated viscometers in artificial hearts. In the proposed method, the blood viscosity is measured by applying radial vibrational excitation to the impeller in a ventricular assist device using its magnetic levitation system. During the measurement, blood is exposed to a combination of a low shear rate (≈100/s) generated by the radial vibration of the impeller and a high shear rate (>10,000/s) generated by the impeller’s rotation. The apparent viscosity of blood depends on the shear rate, so we determined which shear rate was the dominant one in the proposed method. The measurement results showed that the viscosity measured by the proposed method was in good agreement with the reference viscosity measured with a high shear rate. The mean absolute deviation in the measurements using the proposed method and those obtained using a concentric cylindrical viscometer at a high shear rate was 0.12 mPa s for four samples of porcine blood, with viscosities ranging from 2.32 to 2.75 mPa s.

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Methods for determination of stagnation in pneumatic ventricular assist devices

The International Journal of Artificial Organs ◽

10.1177/0391398818790204 ◽

2018 ◽

Vol 41 (10) ◽

pp. 653-663 ◽

Cited By ~ 2

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.

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Test Procedure for a New Type of a Ventricular Assist Device Based on a Viscous Friction Pump

Vestnik of Experimental and Clinical Surgery ◽

10.18499/2070-478x-2020-13-3-256-261 ◽

2020 ◽

Vol 13 (3) ◽

pp. 256-261

Author(s):

Maksim Zhulkov ◽

Alexander Golovin ◽

Alexander Grenaderov ◽

Vitaliy Tsirikhov ◽

Azat Sabetov ◽

...

Keyword(s):

Ventricular Assist Device ◽

Test Procedure ◽

Viscous Friction ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Laboratory Animals ◽

Implantation Technique ◽

Assist Device ◽

Ventricular Assist ◽

Mini Pigs

Introduction. Currently, the possibility of effective correction of multiple organ failure and increasing the life expectancy of patients with critical heart failure using the ventricular assist devices (VAD) is absolutely evidenced. The development of alternative analogues of such devices produced within the country has been an urgent problem for many decades. The design of this machine requires the development of a protocol for carrying out complex biomedical studies on the biocompatibility and safety of the new device.The aim of the study was to develop a protocol for testing and conducting comprehensive biomedical biocompatibility studies of a new ventricular assist device in an acute animal experiment.Materials and methods. The study to develop a technique for implanting a left-ventricular assist device (LVAD) in an acute experiment included female mini-pigs, weighed 40-60 kg. In a series of acute experiments, 5 implantations of a disk pump as a LVAD were performed with a maximum observation period equal 6 hours.Results. In the series of acute experiments, an implantation technique was developed and the fundamental possibility of a viscous friction pump application as a ventricular assist device was evidenced. In all experiments (n = 5), the average level of free hemoglobin did not exceed 2.6 mg%, which supports safety of performance of the viscous friction pump regarding blood erythrocytes. None of the experiments recorded episodes of pump shut-off or breakdown.Conclusions. The series of acute experiments on mini-pigs helped reveal a number of anatomical and physiological features of this animal species that significantly complicated implementation of persistent observation. However, the developed experimental LVAD test methodology can be recommended for use in further chronic experiments on large laboratory animals (calves).

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Whole blood viscosity in the evaluation of thrombogenic milieu in mitral stenosis

Biomarkers in Medicine ◽

10.2217/bmm-2020-0329 ◽

2021 ◽

Vol 15 (3) ◽

pp. 181-190

Author(s):

Elif H Ozcan Cetin ◽

Mehmet S Cetin ◽

Mustafa B Ozbay ◽

Hasan C Könte ◽

Nezaket M Yaman ◽

...

Keyword(s):

Shear Rate ◽

Blood Viscosity ◽

Whole Blood ◽

Mitral Stenosis ◽

High Shear Rate ◽

High Shear ◽

Whole Blood Viscosity ◽

Spontaneous Echo Contrast ◽

Shear Rates ◽

Low Shear

Aim: We aimed to assess the association of whole blood with thromboembolic milieu in significant mitral stenosis patients. Methodology & results: We included 122 patients and classified patients into two groups as having thrombogenic milieu, thrombogenic milieu (+), otherwise patients without thrombogenic milieu, thrombogenic milieu (-). Whole blood viscosity (WBV) in both shear rates were higher in thrombogenic milieu (+) group comparing with thrombogenic milieu (-). WBV at high shear rate and WBV at low shear rate parameters were moderately correlated with grade of spontaneous echo contrast. Adjusted with other parameters, WBV parameters at both shear rates were associated with presence of thrombogenic milieu. Discussion & conclusion: We found that extrapolated WBV at both shear rates was significantly associated with the thrombogenic milieu in mitral stenosis. This easily available parameter may provide additional perspective about thrombogenic diathesis.

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Optimization with levosimendan improves outcomes after left ventricular assist device implantation

European Journal of Cardio-Thoracic Surgery ◽

10.1093/ejcts/ezz159 ◽

2019 ◽

Vol 57 (1) ◽

pp. 176-182

Author(s):

Sinan Sabit Kocabeyoglu ◽

Umit Kervan ◽

Dogan Emre Sert ◽

Mehmet Karahan ◽

Emre Aygun ◽

...

Keyword(s):

Right Ventricular ◽

Left Ventricular Assist Device ◽

Ventricular Assist Device ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Assist Device ◽

Ventricular Assist ◽

Device Implantation ◽

Left Ventricular Assist ◽

Right Ventricular Assist Device

Abstract OBJECTIVES The aim of this study was to examine the haemodynamic effects of preoperative levosimendan infusion in patients who underwent left ventricular assist device implantation and evaluate the prognoses. METHODS Between May 2013 and October 2018, 85 adult patients who underwent left ventricular assist device implantation were included; 44 and 41 patients suffered from dilated cardiomyopathy and ischaemic cardiomyopathy, respectively. Patients were divided into 2 groups: group A (58 patients) included those who received levosimendan infusion in addition to other inotropes and group B (27 patients) included those who received inotropic agents other than levosimendan. Levosimendan infusion was started at a dose of 0.1 µg⋅kg−1⋅min−1 for a maximum of 48 h without a bolus. The primary outcome was early right ventricular failure (RVF). The secondary outcomes were in-hospital mortality, need for right ventricular assist device, late RVF and recovery of end-organ functions. The safety end points of levosimendan included hypotension, atrial fibrillation, ventricular tachycardia or fibrillation and resuscitated cardiac arrest. RESULTS Patient characteristics were similar in both groups. No significant differences between groups were observed in the rates of early mortality, RVF, need for right ventricular assist device, cardiopulmonary bypass time and intensive care unit stay. Survival rates at 30 days, 1 year and 3 years and freedom from late RVF were similar between the groups. Administration of levosimendan was safe, generally well-tolerated and not interrupted because of side effects. CONCLUSIONS Levosimendan therapy was well-tolerated in patients who received permanent left ventricular assist devices. Combined preoperative therapy with inotropes and levosimendan significantly improves end-organ functions.

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Blood damage in Left Ventricular Assist Devices: Pump thrombosis or system thrombosis?

The International Journal of Artificial Organs ◽

10.1177/0391398818806162 ◽

2018 ◽

Vol 42 (3) ◽

pp. 113-124 ◽

Cited By ~ 6

Author(s):

Matteo Selmi ◽

Wei-Che Chiu ◽

Venkat Keshav Chivukula ◽

Giulio Melisurgo ◽

Jennifer Ann Beckman ◽

...

Keyword(s):

Left Ventricular Assist Device ◽

Ventricular Assist Device ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Left Ventricular Assist Devices ◽

Assist Device ◽

Ventricular Assist ◽

Assist Devices ◽

Pump Thrombosis ◽

Left Ventricular Assist

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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Microaxial Flow Left Ventricular Assist Device as a Bridge to Transplantation after LVAD Malfunction

Texas Heart Institute Journal ◽

10.14503/thij-14-4654 ◽

2015 ◽

Vol 42 (6) ◽

pp. 572-574

Author(s):

Heidi J. Reich ◽

Aamir Shah ◽

Babak Azarbal ◽

Jon Kobashigawa ◽

Jaime Moriguchi ◽

...

Keyword(s):

Left Ventricular Assist Device ◽

Ventricular Assist Device ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Left Ventricular Assist Devices ◽

Bridge To Transplantation ◽

Assist Device ◽

Ventricular Assist ◽

Device Malfunction ◽

Left Ventricular Assist

Evolving technology and improvements in the design of modern, continuous-flow left ventricular assist devices have substantially reduced the rate of device malfunction. As the number of implanted devices increases and as survival prospects for patients with a device continue to improve, device malfunction is an increasingly common clinical challenge. Here, we present our initial experience with an endovascular microaxial flow left ventricular assist device as a successful bridge to transplantation in a 54-year-old man who experienced left ventricular assist device malfunction.

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Širdies nepakankamumo gydymas implantuojant dirbtinį skilvelį INCOR

Lietuvos chirurgija ◽

10.15388/lietchirur.2007.3.2230 ◽

2007 ◽

Vol 5 (3) ◽

pp. 0-0

Author(s):

Kęstutis Ručinskas ◽

Saulius Miniauskas ◽

Gintaras Rasimavičius ◽

Rimantas Bubulis ◽

Stanislovas Stankevič ◽

...

Keyword(s):

Heart Failure ◽

Ventricular Assist Device ◽

Left Ventricular ◽

University Hospital ◽

Ventricular Assist Devices ◽

Assist Device ◽

Ventricular Assist ◽

Key Words Heart ◽

Key Words Heart Failure ◽

Vilnius University

Kęstutis Ručinskas1, Saulius Miniauskas1, Gintaras Rasimavičius1, Rimantas Bubulis2, Stanislovas Stankevič2, Vaclovas Jurkuvėnas2, Gitana Žemaitytė3, Vytė Valerija Maneikienė3, Vytautas Sirvydis1, Aleksandras Taucevičius41 Vilniaus universiteto Širdies chirurgijos centras, Santariškių g. 2, LT-08661 Vilnius2 Vilniaus universiteto ligoninės Santariškių klinikų Anesteziologijos,intensyviosios terapijos ir skausmo gydymo centras, Santariškių g. 2, LT-08661 Vilnius3 Vilniaus universiteto ligoninės Santariškių klinikų Širdies chirurgijos centras,Santariškių g. 2, LT-08661 Vilnius4 Vilniaus universiteto Širdies ir kraujagyslių ligų klinika, Santariškių g. 2, LT-08661 VilniusEl paštas: [email protected] Dirbtinis implantuojamas pastovios tėkmės kairysis skilvelis INCOR Vilniaus universiteto Širdies chirurgijos centre naudojamas nuo 2003 metų. Pacientams, kuriems nustatytas kraštutinis širdies nepakankamumas, implantuota 14 dirbtinių skilvelių. Po prijungimo 9 pacientai buvo išrašyti į namus, 4 iš jų sulaukė širdies persodinimo operacijos. Šiuo metu ambulatoriškai stebimi 4 pacientai, kuriems implantuotas INCOR skilvelis. Bendras pacientų stebėjimo laikas yra daugiau kaip 8,5 metų. Dirbtinio skilvelio INCOR implantacija yra labai efektyvus atrinktos grupės pacientų širdies nepakankamumo gydymo būdas. Pagrindiniai žodžiai: širdies nepakankamumas, dirbtinis skilvelis, širdies persodinimas Treatment of heart failure by implanting an INCOR left ventricular assist device Kęstutis Ručinskas1, Saulius Miniauskas1, Gintaras Rasimavičius1, Rimantas Bubulis2, Stanislovas Stankevič2, Vaclovas Jurkuvėnas2, Gitana Žemaitytė3, Vytė Valerija Maneikienė3, Vytautas Sirvydis1, Aleksandras Taucevičius41 Cardial Surgery Centre, Vilnius University, Santariškių str. 2, LT-08661 Vilnius, Lithuania2 Vilnius University Hospital „Santariškių klinikos“, Anesthesiology,Intensive Care and Pain Management Center, Santariškių str. 2, LT-08661 Vilnius, Lithuania 3 Cardial Surgery Centre of Vilnius University Hospital „Santariškių klinikos“,Santariškių str. 2, LT-08661 Vilnius, Lithuania4 Vilnius University, Clinic of Cardiovascular Diseases,Santariškių str. 2, LT-08661 Vilnius, LithuaniaE-mail: [email protected] Continuous blood flow ventricular assist devices, INCOR, are used at Vilnius University Cardial Surgery Centre since 2003. Fourteen of them were implanted to terminal heart failure patients. After the procedure, 9 patients were discharged home and 4 received heart transplant. At the present time, four patients with INCOR are being observed at home. The cumulative time of the patients with the INCOR assist device is 8.5 years. Effective treatment for a selected group of patients with heart failure is ventricular assist device INCOR implantation. Key words: heart failure, assist device, heart transplantation

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Management of a Pediatric Patient With a Left Ventricular Assist Device and Symptomatic Acquired von Willebrand Syndrome Presenting for Orthotopic Heart Transplant

Seminars in Cardiothoracic and Vascular Anesthesia ◽

10.1177/1089253220949386 ◽

2020 ◽

Vol 24 (4) ◽

pp. 355-359

Author(s):

Kaitlin M Flannery ◽

Komal Kamra ◽

Katsuhide Maeda ◽

Paul Shuttleworth ◽

Christopher Almond ◽

...

Keyword(s):

Left Ventricular Assist Device ◽

Heart Transplant ◽

Ventricular Assist Device ◽

Left Ventricular ◽

Ventricular Assist Devices ◽

Assist Device ◽

Ventricular Assist ◽

Acquired Von Willebrand Syndrome ◽

Left Ventricular Assist ◽

Von Willebrand

We present the successful perioperative management of an 11-year-old patient presenting for heart transplant with a left ventricular assist device, symptomatic acquired von Willebrand syndrome, and recent preoperative intracranial hemorrhage. A brief review of the pathophysiology of acquired von Willebrand syndrome is included. As the number of pediatric patients supported with ventricular assist devices continues to increase, the management of symptomatic acquired von Willebrand syndrome during the perioperative period is an important consideration for anesthesiologists.

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