OBJECTIVE: The purpose of this study was to evaluate the system's performance during treadmill tests to maximum exertion in a subset of patients within the Micra Transcatheter Pacing Study.
METHODS: Patients underwent treadmill testing at 3 or 6 months postimplant with algorithm programming at physician discretion. Normalized sensor rate (SenR) relative to the programmed upper sensor rate was modeled as a function of normalized workload in metabolic equivalents (METS) relative to maximum METS achieved during the test. A normalized METS and SenR were determined at the end of each 1-minute treadmill stage. The proportionality of SenR to workload was evaluated by comparing the slope from this relationship to the prospectively defined tolerance margin (0.65-1.35).
RESULTS: A total of 69 treadmill tests were attempted by 42 patients at 3 and 6 months postimplant. Thirty tests from 20 patients who completed ≥4 stages with an average slope of 0.86 (90% confidence interval 0.77-0.96) confirmed proportionality to workload. On an individual test basis, 25 of 30 point estimates (83.3%) had a normalized slope within the defined tolerance range (range 0.46-1.08).
CONCLUSION: Accelerometer-based rate adaptive pacing was proportional to workload, thus confirming rate adaptive pacing commensurate to workload is achievable with an entirely intracardiac pacing system.
OBJECTIVES:: The aim was to investigate their dynamic characteristics and create a relationship between these dynamic data and the prescription of foot.
STUDY DESIGN:: Experimental Assessment.
METHODS:: This article presents the modal analysis results of the full range of Össur Flex-Run™ running feet that are commercially available (1LO-9LO) using experimental modal analysis technique under a constant mass at 53 kg and boundary condition.
RESULTS:: It was shown that both the undamped natural frequency and stiffness increase linearly from the lowest to the highest stiffness category of foot which allows for a more informed prescription of foot when tuning to a matched natural frequency. The low damping characteristics determined experimentally that ranged between 1.5% and 2.0% indicates that the feet require less input energy to maintain the steady-state cyclic motion before take-off from the ground. An analysis of the mode shapes also showed a unique design feature of these feet that is hypothesised to enhance their performance.
CONCLUSION:: A better understanding of dynamic characteristics of the feet can help tune the feet to the user's requirements in promoting a better gait performance.
CLINICAL RELEVANCE: The dynamic data determined from this study are needed to better inform the amputees in predicting the natural frequency of the foot prescribed. The amputees can intuitively tune the cyclic body rhythm during walking or running to match with the natural frequency. This could eventually promote a better gait performance.