Impact of vWF Activity in the Long-term Management of Centrifugal Type Continuous-flow LVAD Patients

Ichihara, Yuki; Nishinaka, Tomohiro; Yamada, Yukiko; Hoki, Ryogo; Kashiwamura, Chihiro; Komagamine, Masahide; Tsukui, Hiroyuki; Saito, Satoshi; Nagashima, Mitsugi; Yamazaki, Kenji

doi:10.1016/j.healun.2014.01.268

Cited by 2 publications

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“…Thus, the significant differences observed during these in vitro VWF-compatibility tests of the HMII and HVAD suggest VWF multimer and functional changes may be a more sensitive indicator of shear-related blood trauma than clinical non-surgical bleeding rates. The results of VWF-compatibility testing of the EVAHEART VAD supports the proposition that benchtop testing 18,19 reflected clinical results 20,21 . We observed that the Levacor preserved VWF function and multimer distribution; however, this device is no longer in use and clinical VWF-compatibility and bleeding rates have not been published.…”

Section: Discussionsupporting

confidence: 65%

Benchtop von Willebrand Factor Testing: Comparison of Commercially Available Ventricular Assist Devices and Evaluation of Variables for a Standardized Test Method

et al. 2019

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Gastrointestinal bleeding occurs in 20-30% of patients receiving ventricular assist devices (VADs) due, in part, to acquired von Willebrand syndrome. We examined factors to optimize a benchtop method to quantify changes in von Willebrand Factor (VWF) multimer distribution and function in VADs, then applied them to evaluate commercially available devices. Human plasma was circulated through flow loops with VADs. Several experimental conditions were examined, including temperature, viscosity, and enzyme inhibition. Samples were analyzed for VWF collagen-binding activity (VWF:CB) and VWF antigen level. von Willebrand Factor multimer profiles were quantified using gel electrophoresis, near-infrared in-gel visualization, and densitometric analysis. The VWF:CB/antigen ratio in the HeartMate II, CentriMag, and HVAD exhibited average decreases of 46%, 44%, and 36% from baseline after 360 minutes of operation. High molecular weight (hVWF) multimer loss occurred within 30 minutes, although the Levacor and control loop profiles were unchanged. Varying temperature and viscosity altered hVWF degradation rate, but not the final results. Inhibition of ADAMTS13 can potentially distinguish mechanoenzymatic cleavage of VWF from mechanical degradation. We developed a repeatable benchtop method to evaluate VWF compatibility of VADs similar to hemolysis testing that can be adopted for preclinical VAD evaluation.

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Section: Discussionsupporting

confidence: 65%

Benchtop von Willebrand Factor Testing: Comparison of Commercially Available Ventricular Assist Devices and Evaluation of Variables for a Standardized Test Method

et al. 2019

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“…The pump is designed to achieve low shear stress and provides wider clearance between the impeller and the housing . These features may contribute to fewer adverse effects on the blood and a lower rate of AVWD and GI bleeding . We developed a rotational speed (RS) modulation system for EVAHEART that can change the RS in synchronization with the cardiac cycle of the native heart.…”

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confidence: 99%

Influence of a Rotational Speed Modulation System Used With an Implantable Continuous‐Flow Left Ventricular Assist Device on von Willebrand Factor Dynamics

et al. 2016

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We have developed a rotational speed (RS) modulation system for a continuous-flow left ventricular assist device (EVAHEART) that can change RS in synchronization with a patient's electrocardiogram. Although EVAHEART is considered not to cause significant acquired von Willebrand syndrome, there remains a concern that the repeated acceleration and deceleration of the impeller may degrade von Willebrand factor (vWF) multimers. Accordingly, we evaluated the influence of our RS modulation system on vWF dynamics. A simple mock circulation was used. The circulation was filled with whole bovine blood (650 mL), and the temperature was maintained at 37 ± 1°C. EVAHEART was operated using the electrocardiogram-synchronized RS modulation system with an RS variance of 500 rpm and a pulse frequency of 60 bpm (EVA-RSM; n = 4). The pumps were operated at a mean flow rate of 5.0 ± 0.2 L/min against a mean pressure head of 100 ± 3 mm Hg. The continuous-flow mode of EVAHEART (EVA-C; n = 4) and ROTAFLOW (ROTA; n = 4) was used as controls. Whole blood samples were collected at baseline and every 60 min for 6 h. Complete blood counts (CBCs), normalized indexes of hemolysis (NIH), vWF antigen (vWF:Ag), vWF ristocetin cofactor (vWF:Rco), the ratio of vWF:Rco to vWF:Ag (Rco/Ag), and high molecular weight multimers (HMWM) of vWF were evaluated. There were no significant changes in CBCs throughout the 6-h test period in any group. NIH levels of EVA-RSM, EVA-C, and ROTA were 0.0035 ± 0.0018, 0.0031 ± 0.0007, and 0.0022 ± 0.0011 g/100 L, respectively. Levels of vWF:Ag, vWF:Rco, and Rco/Ag did not change significantly during the test. Immunoblotting analysis of vWF multimers showed slight degradation of HMWM in all groups, but there were no significant differences between groups in the ratios of HMWM to low molecular weight multimers, calculated by densitometry. This study suggests that our RS modulation system used with EVAHEART does not have marked adverse influences on vWF dynamics. The low NIH and the absence of significant decreases in CBCs indicate that EVAHEART is hemocompatible, regardless of whether it is operated with the RS modulation system.

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Impact of vWF Activity in the Long-term Management of Centrifugal Type Continuous-flow LVAD Patients

Cited by 2 publications

References 0 publications

Benchtop von Willebrand Factor Testing: Comparison of Commercially Available Ventricular Assist Devices and Evaluation of Variables for a Standardized Test Method

Benchtop von Willebrand Factor Testing: Comparison of Commercially Available Ventricular Assist Devices and Evaluation of Variables for a Standardized Test Method

Influence of a Rotational Speed Modulation System Used With an Implantable Continuous‐Flow Left Ventricular Assist Device on von Willebrand Factor Dynamics

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