Outcomes of systemic bivalirudin and sodium bicarbonate purge solution for Impella 5.5.

BACKGROUND: Impella 5.5 (Abiomed; Danvers, MA) (IMP5) is a commonly used, surgically implanted, tMCS device that requires systemic anticoagulation and purge solution to avoid pump failure. To avoid heparin-induced thrombocytopenia (HIT) from unfractionated heparin (UFH) use, our program has explored the utility of bivalirudin (BIV) for systemic anticoagulation and sodium bicarbonate-dextrose purge solution (SBPS) in IMP5.5. METHODS: This single center, retrospective study included 34 patients supported on IMP5.5 with BIV based AC and SBPS between December 1st 2020 to December 1st 2021.The efficacy and safety end points were incidence of development of HIT, Tissue Plasminogen Activator (tPA) use for suspected pump thrombosis, stroke, and device failure as well as clinically significant bleeding. RESULTS: The median duration of IMP5.5 support was 9.8 days (IQR: 6-15). Most patients were bridged to HTX (58%) followed by recovery (27%) and LVAD implantation (15%). Patients were therapeutic on bivalirudin for 64% of their IMP5.5 support. One patient (2.9%) suffered from ischemic stroke and 26.5% (9) patients developed clinically significant bleeding. tPA was administered to 7(21%) patients. One patient in the entire cohort developed HIT. CONCLUSIONS: Our experience supports the use of systemic BIV and SBPS as a method to avoid heparin exposure in a patient population predisposed to the development of HIT.

Device profile of the Impella 5.0 and 5.5 system for mechanical circulatory support for patients with cardiogenic shock: overview of its safety and efficacy.

INTRODUCTION: Trans-valvular micro-axial flow pumps such as Impella are increasingly utilized in patients with cardiogenic shock [CS]. A number of different Impella devices are now available providing a wide range of cardiac output. Among these, the Impella 5.0 and recently introduced Impella 5.5 pumps can provides 5.55 L/min of flow, enabling complete left ventricular support with more favorable hemodynamic effects on myocardial oxygen consumption and left ventricular unloading. These devices require placement of a surgical conduit graft for endovascular delivery, but are increasingly being used in patients with CS due to acutely decompensated heart failure [ADHF], acute myocardial infarction [AMI] and after cardiac surgery as a bridge to transplant or durable ventricular assist device surgery or myocardial recovery. AREAS COVERED: This review focuses on the device profile and use of the Impella 5.0 and 5.5 systems in patients with CS. Specifically; we reviewed the published literature for Impella 5.0 device to summarize data regarding safety and efficacy. EXPERT OPINION: The Impella 5.0 and 5.5 are trans-valvular micro-axial flow pumps for which the current data suggest excellent safety and efficacy profiles as approaches to provide circulatory support, myocardial unloading, and axillary placement enabling patient mobilization and rehabilitation. ABBREVIATIONS: pMCS, Percutaneous mechanical circulatory support devices; CS, Cardiogenic shock; ADHF, Acute decompensated heart failure; AMI, Acute myocardial infarction; LVAD, Left ventricular assist deviceI; ABP, Intra-aortic balloon pump; VA-ECLS, Veno-arterial extracorporeal life support.

Outcomes of systemic anticoagulation with bivalirudin for Impella 5.0.

Temporary mechanical circulatory support (tMCS) devices are used for the management of cardiogenic shock. The Impella 5.0 (Abiomed; Danvers, MA) (IMP5) is a commonly used, surgically implanted, tMCS device that requires systemic anticoagulation and purge solution to avoid pump failure. To avoid heparin-induced thrombocytopenia (HIT) from unfractionated heparin (UFH) use, our program has explored the utility of bivalirudin (BIV) for systemic anticoagulation in IMP5. This single center, retrospective study included patients supported on IMP5 with BIV based AC. The efficacy and safety end points were recovery, bridge to left ventricular assist device (LVAD), cardiac transplant (HTX), or death as well as clinically significant bleeding, incidence of Tissue Plasminogen Activator (tPA) use for suspected pump thrombosis, stroke, and device failure. There were 31 patients included, and 26 (84%) received BIV purge solutions. The median duration of IMP5 was 6 (IQR 4-10) days. Most patients were bridged to LVAD (39%, 12); 16% (5) were bridged to HTX, 16% (5) recovered, and 29% (9) died. One patient (3%) suffered from ischemic stroke and 12% (4) patients developed clinically significant bleeding. tPA was administered to 8 (26%) patients. Logistic regression analysis demonstrated that duration of IMP5 was a significant predictor of tPA use (OR 1.28; 95% Confidence Interval 1.04-1.56). There were no cases of pump failure. Our experience highlights the feasibility of utilizing BIV for routine AC use in IMP5.

Finding a proper "Mate": Comparison of left ventricular assist devices using cerebral oximetry.

INTRODUCTION: Axial-flow and centrifugal-flow left ventricular assist devices (LVAD) have been utilized in the management of heart failure, but it remains unknown whether these devices differ in end-organ perfusion. Our goal was to evaluate the association between device type and regional cerebral oxygen saturation (rSO2), and determine if this confers any benefit in short-term postoperative outcomes. METHODS: Adult patients who underwent primary LVAD implantation at our institution from 2014 to 2019 were retrospectively analyzed. Patients were stratified into axial-flow and centrifugal-flow groups. Intraoperative rSO2 readings were used to calculate the change in mean rSO2 from pre- to post-bypass. Multivariable modeling was performed to compare delta rSO2 between groups, and to analyze the association between LVAD type and postoperative outcomes. RESULTS: There were 152 patients included, of which 76 had an axial-flow device and 76 had a centrifugal-flow device implanted. The rSO2 level increased from pre-bypass to post-bypass on average 3.5% (CI: 2.1 to 5.0) for the axial group compared to 0.1% (CI: -1.2 to 1.4) for the centrifugal group, which was a significant difference (ß = -2.22, CI: -4.21 to -0.32, p = 0.022). Axial devices approached significance for lower odds of postoperative complications (OR: 0.35, CI: 0.11 to 1.06, p = 0.063), and were associated with significantly shorter ICU LOS (ß = -0.36, CI: -0.60 to -0.11, p = 0.004). CONCLUSION: Axial devices resulted in a greater increase in rSO2 than centrifugal pumps after separation from CPB. Further investigation is warranted to evaluate the effect of LVAD selection on long-term end-organ perfusion and subsequent patient outcomes.

Impeller geometry definition of the transventricular assist device.

According to the World Health Organization, cardiovascular disease is the number one cause of death worldwide, except Africa, where Acquired Immune Deficiency Syndrome is the leading cause of death. In this scenario, the ventricular assist device (VAD) remains the unique alternative to extend patient life until heart transplantation. At Dante Pazzanese Institute of Cardiology, the research and development of an axial flow VAD to be fully implantable within the heart was started. This pump, denominated Transventricular Assist Device (TVAD), can be surgically implanted through a small left intercostal incision in a minimally invasive manner. The goal of this work is to analyze the impeller geometries of the TVAD, to avoid high shear stresses in the fluid and aim for the best conditions to support the circulatory system using computational fluid dynamics and in vitro tests. Different rotor geometries were selected according to the literature; based on the results, the best rotor was elected. This rotor contains a pair of spiral blades of constant and relatively high pitch, which pumps liquid at a flow rate of 3 L/min at 73 mm Hg. It is also expected that this rotor presents a moderate hemolysis since the shear rate is acceptable.

Recurrent pump thrombosis is common after axial continuous-flow left ventricular assist device exchange.

In selected patients with left ventricular assist device-associated infection or malfunction, pump exchange may become necessary after conservative treatment options fail and heart transplantation is not readily available. We examined the survival and complication rate in patients (⩾19 years of age) who underwent HeartMate II to HeartMate II exchange at our institution from 1 January 2010 to 28 February 2018. Clinical outcomes were analyzed and compared for patients who underwent exchange for pump thrombosis (14 patients), breach of driveline integrity (5 patients), and device-associated infection (2 patients). There were no differences in 30-day mortality (p = 0.58), need for temporary renal replacement therapy (p = 0.58), right ventricular mechanical support (p = 0.11), and postoperative stroke (p = 0.80) among groups. Survival at 1 year was 90% ± 7% for the whole cohort and 85% ± 10% for those who underwent exchange for pump thrombosis. In patients exchanged for device thrombosis, freedom from re-thrombosis and survival free from pump re-thrombosis at 1 year were 49% ± 16% and 42% ± 15%, respectively. No association of demographic and clinical variables with the risk of recurrent pump thrombosis after the first exchange was identified. Survival after left ventricular assist device exchange compares well with published results after primary left ventricular assist device implantation. However, recurrence of thrombosis was common among patients who required a left ventricular assist device exchange due to pump thrombosis. In this sub-group, consideration should be given to alternative strategies to improve the outcomes.

Multiple approaches to predicting oxygen and glucose consumptions by HepG2 cells on porous scaffolds in an axial-flow bioreactor.

In this study, the distribution of oxygen and glucose was evaluated along with consumption by hepatocytes using three different approaches. The methods include (i) Computational Fluid Dynamics (CFD) simulation, (ii) residence time distribution (RTD) analysis using a step-input coupled with segregation model or dispersion model, and (iii) experimentally determined consumption by HepG2 cells in an open-loop. Chitosan-gelatin (CG) scaffolds prepared by freeze-drying and polycaprolactone (PCL) scaffolds prepared by salt leaching technique were utilized for RTD analyses. The scaffold characteristics were used in CFD simulations i.e. Brinkman's equation for flow through porous medium, structural mechanics for fluid induced scaffold deformation, and advection-diffusion equation coupled with Michaelis-Menten rate equations for nutrient consumption. With the assumption that each hepatocyte behaves like a micro-batch reactor within the scaffold, segregation model was combined with RTD to determine exit concentration. A flow rate of 1 mL/min was used in the bioreactor seeded with 0.6 × 10(6) HepG2 cells/cm(3) on CG scaffolds and oxygen consumption was measured using two flow-through electrodes located at the inlet and outlet. Glucose in the spent growth medium was also analyzed. RTD results showed distribution of nutrients to depend on the surface characteristics of scaffolds. Comparisons of outlet oxygen concentrations between the simulation results, and experimental results showed good agreement with the dispersion model. Outlet oxygen concentrations from segregation model predictions were lower. Doubling the cell density showed a need for increasing the flow rate in CFD simulations. This integrated approach provide a useful strategy in designing bioreactors and monitoring tissue regeneration.

Hemorrhage and thrombosis with different LVAD technologies: a matter of flow?

BACKGROUND: Much of the morbidity and mortality associated with ventricular assist devices (VADs) is due to haemorrhagic and thrombotic complications. To manage antithrombotic therapy, interactions between the patient and pump should be better understood. METHODS: We have compared the Jarvik 2000, an axial flow left ventricular assist device (LVAD), with the HeartWare ventricular assist device (HVAD) centrifugal pump, regarding conventional laboratory findings, thromboelastometric and aggregometric tests. RESULTS: Patients with the Jarvik 2000 experienced a significant reduction in platelet count following implantation, a phenomenon not seen with the HeartWare model. Conversely, we observed that levels of platelet activation, as assessed by a platelet function analyzer, and activation of the coagulation system, as assessed by thromboelastometry, were significantly greater in the HeartWare group. CONCLUSIONS: It seems that axial flow pumps, being more destructive on blood cells, tend to reduce platelet numbers. On the other hand, centrifugal flow is associated with a hypercoagulable state, possibly resulting from the activation of the coagulation system in the absence of platelet destruction.

Clinical evaluation of the Spiral Pump® after improvements to the original project in patients submitted to cardiac surgeries with cardiopulmonary bypass / Avaliação clínica da bomba espiral (Spiral Pump®) após aperfeiçoamentos introduzidos ao projeto original em pacientes submetidos a cirurgias cardíacas com circulação extracorpórea

Objective: The objective of this paper is to present the results from Spiral Pump clinical trial after design modifications performed at its previous project. This pump applies axial end centrifugal hydraulic effects for blood pumping during cardiopulmonary bypass for patients under cardiac surgery. Methods: This study was performed in 52 patients (51% males), between 20 to 80 (67±14.4) years old weighing 53 to 102 (71.7±12.6) kg, mostly under myocardial revascularization surgery (34.6%) and valvular surgery (32.8%). Besides the routine evaluation of the data observed in these cases, we monitored pump rotational speed, blood flow, cardiopulmonary bypass duration, urine free hemoglobin for blood cell trauma analysis (+ to 4+), lactate desidrogenase (UI/L), fibrinogen level (mg/dL) and platelet count (nº/mm3). Results: Besides maintaining appropriate blood pressure and metabolic parameters it was also observed that the Free Hemoglobin levels remained normal, with a slight increase after 90 minutes of cardiopulmonary bypass. The Lactate Dehydrogenase showed an increase, with medians varying between 550-770 IU/L, whereas the decrease in Fibrinogen showed medians of 130-100 mg/dl. The number of platelets showed a slight decrease with the medians ranging from 240,000 to 200,000/mm3. No difficulty was observed during perfusion terminations, nor were there any immediate deaths, and all patients except one, were discharged in good condition. CONCLUSION: The Spiral Pump, as blood propeller during cardiopulmonary bypass, demonstrated to be reliable and safe, comprising in a good option as original and national product for this kind of application. .

Objetivos: Apresentar resultados da aplicação da bomba espiral que emprega efeitos hidráulicos centrífugo e axial de bombeamento como elemento propulsor do circuito de circulação extracorpórea em pacientes submetidos a cirurgias cardíacas após modificações introduzidas no design do projeto original. Métodos: O estudo foi realizado em 52 pacientes (51% masculinos), com idade entre 20 a 80 (67±14,4) anos, peso 53 a 102 (71,7±12,6) kg, submetidos na maioria a cirurgia de revascularização miocárdica (34,6%) e Orovalvar (32,8%). Além das avaliações rotineiras, foram registrados rotação, tempo de CEC e para análise do impacto traumático à crase sanguínea, hemoglobina livre na urina (+ a 4+), desidrogenase láctica, fibrinogênio (mg/dL) e contagem de plaquetas (nº/mm3). Resultados: Observou-se a manutenção de parâmetros pressóricos e metabólicos adequados. Quanto aos marcadores de danos à crase sanguínea, as alterações estiveram proporcionais ao tempo maior de circulação extracorpórea. Os níveis de Hemoglobina Livre permaneceram com valores normais, com ligeiro aumento a partir dos 90 minutos de circulação extracorpórea. A Desidrogenase Láctica mostrou aumento, variando as medianas entre 550 a 770 UI/L enquanto o Fibrinogênio mostrou queda das medianas de 130 a 100 mg/dl. O número de plaquetas mostrou ligeira queda das medianas variando entre 240.000 a 200.000/mm3. Não ocorreram dificuldades de saída de perfusão, não se observou óbito imediato e todos os pacientes, exceto 1, obtiveram alta hospitalar. Conclusão: A bomba espiral aplicada como bomba propulsora de sangue durante cirurgia cardíaca se mostrou confiável e segura, não causou impacto traumático ...