mVEGAS - mobile smartphone-based spatiotemporal gait analysis in healthy and ataxic gait disorders.

BACKGROUND: Quantitative gait assessment is increasingly applied in fall risk stratification, diagnosis, and disease monitoring of neuro-geriatric gait disorders. Its broad application, however, demands for low-cost and mobile solutions that facilitate high-quality assessment outside laboratory settings. The aim of this study was to present and evaluate the concurrent validity of a mobile and low-cost gait assessment tool (mVEGAS) that combines body-fixed inertial sensors and a smartphone-based video capture for spatiotemporal identification of gait sequences. METHODS: Initially, we examined potential interferences of wearing mVEGAS with walking performance in a cohort of 20 young healthy individuals (31.1 ± 10.1 years; 8 females). Subsequently, we assessed the concurrent validity of mVEGAS as compared to a pressure-sensitive gait carpet (GAITRite) in a cohort of 26 healthy individuals (55.8 ± 14.3 years; 10 females) and 26 patients (55.7 ± 14.0; 14 females) with moderate to severe degrees of cerebellar gait ataxia. All participants were instructed to walk at preferred, slow, and fast walking speed and standard average and variability gait measures including velocity, stride length, stride time, base of support, swing and double support phase were examined for agreement between the two systems by absolute error and intraclass correlation coefficients (ICC). RESULTS: Wearing mVEGAS did only marginally interfere with normal walking behavior. mVEGAS-derived average and variability gait measures exhibited good to excellent concurrent validity in healthy individuals (ICCs ranging between 0.645 and 1.000) and patients with gait ataxia (ICCs ranging between 0.788 and 1.000) SIGNIFICANCE: mVEGAS may facilitate high-quality and long-term gait monitoring in different non-specialized environments such as medical practices, nursing homes or community centers.

The role of clonidine in hypertensive heart disease. Influence on myocardial contractility and left ventricular afterload.

The hemodynamic and contractile effects of clonidine were studied in hypertrophied hearts of spontaneously hypertensive rats (Okamoto-Aoki strain, SHR). The hemodynamic pattern was characterized by dose-dependent decreases in systolic blood pressure and systolic wall stress, ie, the afterload imposed upon the left ventricle, whereas left ventricular ejection fraction and stroke volume were unchanged. Even at extremely high doses (10(-5)M/L) there was found no depression of isometric tension development and maximum isotonic shortening velocity of the isolated LV papillary muscle. It is concluded that clonidine may be beneficial in hypertensive heart disease, if ventricular unloading associated with a reduction in myocardial energy demand is desired.