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.     

High resolution muscle measurements provide insights into equinus contractures in patients with cerebral palsy

Muscle contractures that occur after upper motor neuron lesion are often surgically released or lengthened. However, surgical manipulation of muscle length changes a muscle's sarcomere length (L_s), which can affect force production. To predict effects of surgery, both macro‐ (fascicle length (L_f)) and micro‐ (L_s) level structural measurements are needed. Therefore, the purpose of this study was to quantify both L_s and L_f in patients with cerebral palsy (CP) as well as typically developing (TD) children. Soleus ultrasound images were obtained from children with CP and TD children. L_f was determined and, with the joint in the same position, CP biopsies were obtained and formalin fixed, and L_s was measured by laser diffraction. Since soleus L_s values were not measurable in TD children, TD L_s values were obtained using three independent methods. While average L_f did not differ between groups (CP = 3.6 ± 1.2 cm, TD = 3.5 ± 0.9 cm; p > 0.6), L_s was dramatically longer in children with CP (4.07 ± 0.45 µm vs. TD = 2.17 ± 0.24 µm; p < 0.0001). While L_f values were similar between children with CP and TD children, this was due to highly stretched sarcomeres within the soleus muscle. Surgical manipulation of muscle‐tendon unit length will thus alter muscle sarcomere length and change force generating capacity of the muscle. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:33–39, 2015.     

A Web‐Based Early Intervention Can Prevent Long‐Term PTS Reactions in Children With High Initial Distress Following Accidental Injury

The present study explored the targeting of a preventative information provision intervention delivered to children following accidental injury by assessing the impact of initial traumatic distress on response to treatment. Analyses were based on baseline and 6‐month outcome of child traumatic stress in a control (n = 28) and an intervention group (n = 31). Moderation of treatment outcome by initial levels of child traumatic stress was assessed through multiple hierarchical regression analyses. Results indicated the interaction between treatment provision and initial level of posttraumatic stress significantly predicted 6‐month outcome (β = ?.42, p = .019). When initial distress was high, children in the control group demonstrated an increase in trauma symptoms, and had significantly higher trauma symptoms at follow‐up than those in the treatment group (d = 0.94, p = .008). When initial distress was not elevated, no significant differences were noted between the groups. These results indicate that a preventative early intervention may be best targeted at children presenting with the specific risk factor of high initial distress.