The CentriMag Centrifugal Blood Pump as a Benchmark for In Vitro Testing of Hemocompatibility in Implantable Ventricular Assist Devices

Implantable ventricular assist devices (VADs) have proven efficient in advanced heart failure patients as a bridge‐to‐transplant or destination therapy. However, VAD usage often leads to infection, bleeding, and thrombosis, side effects attributable to the damage to blood cells and plasma proteins. Measuring hemolysis alone does not provide sufficient information to understand total blood damage, and research exploring the impact of currently available pumps on a wider range of blood cell types and plasma proteins such as von Willebrand factor (vWF) is required to further our understanding of safer pump design. The extracorporeal CentriMag (Thoratec Corporation, Pleasanton, CA, USA) has a hemolysis profile within published standards of normalized index of hemolysis levels of less than 0.01 g/100 L at 100 mm Hg but the effect on leukocytes, vWF multimers, and platelets is unknown. Here, the CentriMag was tested using bovine blood (n = 15) under constant hemodynamic conditions in comparison with a static control for total blood cell counts, hemolysis, leukocyte death, vWF multimers, microparticles, platelet activation, and apoptosis. The CentriMag decreased the levels of healthy leukocytes (P < 0.006), induced leukocyte microparticles (P < 10^?5), and the level of high molecular weight of vWF multimers was significantly reduced in the CentriMag (P < 10^?5) all compared with the static treatment after 6 h in vitro testing. Despite the leukocyte damage, microparticle formation, and cleavage of vWF multimers, these results show that the CentriMag is a hemocompatible pump which could be used as a standard in blood damage assays to inform the design of new implantable blood pumps.     

Localized orthodontic space closure for unilateral aplasia of lower second premolars

The present study aimed to determine whether routine orthodontic space closure can be successfully achieved in patients with unilateral aplasia of the lower second premolars without extracting contralateral or opposing teeth. The dental records and lateral cephalograms of 17 consecutively treated subjects (11 females, 6 males) aged between 14.8 and 19.3 years at the end of active treatment (mean 16.1 years) were analysed. The spaces were closed by 'push-and-pull' mechanics (PPM). Pre- and post-treatment data were compared using a Student's t-test. At the end of active treatment, all parameters (ANB, SNA, SNB, ML/NL, U1-NA, L1-NB, overbite and overjet, upper and lower midline, upper and lower space balance) presented mean values close to accepted norms with satisfactory standard deviations (SDs). Five indicators of success changed significantly: (1) Space closure in the aplastic region was achieved. (2) On the aplastic side, a mean mesial molar relationship of 1.12 (SD 0.18) cusp width (cw) was achieved. The mean alteration from pre- to post-treatment was 1.53 cw (SD 0.29, P 相似文献   

Virtual implantations to transition from porcine to bovine animal models for a total artificial heart

Realheart total artificial heart (TAH) is a novel, pulsatile, four-chamber total artificial heart which had been successfully tested acutely in a porcine animal model. However, the bovine model is better suited for long-term testing and thus an evaluation of how the design would fit the bovine anatomy was required. Virtual implantation is a method that enables a computer simulated implantation based on anatomical 3D-models created from computer tomography images. This method is used clinically, but not yet adopted for animal studies. Herein, we evaluated its suitability in the redesign of the outer dimensions and vessel connections of Realheart TAH to transition from the porcine to the bovine animal model. Virtual implantations in combination with bovine cadaver studies enabled a series of successful acute bovine implantations. Virtual implantations are a useful tool to replace the use of animals in early device development and refine subsequent necessary in vivo experiments. The next steps are to carry out human virtual implantations and cadaver studies to ensure the design is optimized for all stages of testing as well as the final recipient.