PurposeTo assess the validity of RR intervals and short-term heart rate variability (HRV) data obtained from the Polar V800 heart rate monitor, in comparison to an electrocardiograph (ECG).MethodTwenty participants completed an active orthostatic test using the V800 and ECG. An improved method for the identification and correction of RR intervals was employed prior to HRV analysis. Agreement of the data was assessed using intra-class correlation coefficients (ICC), Bland–Altman limits of agreement (LoA), and effect size (ES).ResultsA small number of errors were detected between ECG and Polar RR signal, with a combined error rate of 0.086 %. The RR intervals from ECG to V800 were significantly different, but with small ES for both supine corrected and standing corrected data (ES <0.001). The bias (LoA) were 0.06 (−4.33 to 4.45 ms) and 0.59 (−1.70 to 2.87 ms) for supine and standing intervals, respectively. The ICC was >0.999 for both supine and standing corrected intervals. When analysed with the same HRV software no significant differences were observed in any HRV parameters, for either supine or standing; the data displayed small bias and tight LoA, strong ICC (>0.99) and small ES (≤0.029).ConclusionsThe V800 improves over previous Polar models, with narrower LoA, stronger ICC and smaller ES for both the RR intervals and HRV parameters. The findings support the validity of the Polar V800 and its ability to produce RR interval recordings consistent with an ECG. In addition, HRV parameters derived from these recordings are also highly comparable.

A large number (163) of features from these histograms were examined, and 38 of these were significantly different (P < 0.05) between the groups. In the hippocampus, evidence was found for AD-related increases in iron deposition (shortened T2) and in the concentration of free tissue water (lengthened T2). Imaging of a section of postmortem brain before and after chemically extracting the iron established the presence of MRI-detectable iron in the hippocampus, cortex, and white matter in addition to brain regions traditionally viewed as containing high iron concentrations.

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01994720.

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Context: There is substantial hospital-level variation in use of tissue plasminogen activator (tPA) for treatment of acute ischemic stroke. Telestroke services can bring neurologic expertise to hospitals with fewer resources.Objective: To determine whether implementation of a telestroke intervention in a large integrated health system would lead to increased tPA utilization and would change rates of hemorrhagic complications.Design: A stepped-wedge cluster randomized trial of 11 community hospitals connected to 2 tertiary care centers via telestroke, implemented at each hospital incrementally during a 1-year period. We examined pre-and postimplementation data from July 2013 through January 2015. A 2-level mixed-effects logistic regression model accounted for the staggered rollout.Main Outcome Measures: Receipt of tPA. Secondary outcome was the rate of significant hemorrhagic complications.Results: Of the 2657 patients, demographic and clinical characteristics were similar in pre-and postintervention cohorts. Utilization of tPA increased from 6.3% before the intervention to 10.9% after the intervention, without a significant change in complication rates. Postintervention patients were more likely to receive tPA than were preintervention patients (odds ratio = 2.0; 95% confidence interval = 1.2-3.4). Before implementation, 8 of the 10 community hospitals were significantly less likely to administer tPA than the highest-volume tertiary care center; however, after implementation, 9 of the 10 were at least as likely to administer tPA as the highest-volume center.Conclusion: Telestroke implementation in a regional integrated health system was safe and effective. Community hospitals' rates of tPA utilization quickly increased and were similar to the largest-volume tertiary care center.