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1 oktober 2013, Item does not contain fulltext, BACKGROUND: The aim of this study was to detect normal changes in fetal two-dimensional speckle-tracking echocardiography-derived values for global and regional longitudinal left and right ventricular strain, strain rate, and time to peak (T2P) global strain during pregnancy. METHODS: Forty-four healthy fetuses were examined prospectively during the second-trimester and third-trimester ultrasound examinations (20-24 and 30-34 weeks, respectively). Clips with high frame rates (mean, 120 frames/sec) of two-dimensional (B-mode) grayscale images of apical or basal four-chamber views of both ventricles were used for offline analyses of global and regional walls and segments (basal, mid, and apical) of myocardial strain and strain rate as well as T2P global strain in the longitudinal direction. RESULTS: There were statistically significant decreases in global and regional strain of the right ventricle between the second and third trimesters. No statistically significant changes were observed in global and regional strain of the left ventricle. Global and regional strain rates of both ventricles decreased in a similar way during pregnancy. The mean T2P longitudinal left ventricular global strain (adjusted for heart rate) increased mildly during fetal life. Whereas T2P longitudinal strain of the left ventricle at 20 to 24 weeks was statistically significantly shorter than that of the right ventricle, no difference in T2P longitudinal strain was found at 30 to 34 weeks of gestation between both ventricles. CONCLUSIONS: The establishment of these changes between the second-trimester and third-trimester two-dimensional speckle-tracking echocardiography-derived reference values is a mandatory prerequisite for its use in evaluating (pathologic) changes in both ventricular functions during pregnancy.

Item does not contain fulltext, BACKGROUND: Data on myocardial deformation during the internationally widely used second-trimester screening are scarce and confusing. Reference values of time to peak strain are missing. The aims of this study were to assess reference values derived from two-dimensional speckle-tracking echocardiography for global and regional longitudinal right ventricular (RV) and left ventricular (LV) strain, strain rate, and time to peak global strain and to determine the influence of heart rate and gender on these strain parameters. METHODS: Seventy-five healthy fetuses were enrolled during second-trimester ultrasound (20-24 weeks). Clips with high frame rates (mean, 132 frames/sec) and two-dimensional (B-mode) grayscale images of apical or basal four-chamber views of both ventricles were used for offline analyses. RESULTS: There were no statistically significant differences in global strain and strain rate between both ventricles (P = .679 and P = .734, respectively) or among the RV, septal, and LV free walls. Regional measurements, modeled also as an interaction of wall and segment (basal mid and apical), showed only a small, statistically significant difference between the basal RV and LV free walls. Strain and strain rate values were independent of heart rate. The mean time to peak LV global strain adjusted for heart rate was statistically significantly shorter than the RV value (P < .0001]). Strain, strain rate, and time to peak global strain were not found to be associated with gender. CONCLUSIONS: The establishment of second-trimester two-dimensional speckle-tracking echocardiographic reference values for global and regional strain, strain rate, and time to peak global strain in a healthy fetal cohort is a mandatory prerequisite for its use in evaluating (pathologic) changes in both ventricular functions during pregnancy.

In this survey recent results about q-analogues of some classical theorems in extremal set theory are collected. They are related to determining the chromatic number of the q-analogues of Kneser graphs. For the proof one needs results on the number of 0-secant subspaces of point sets, so in the second part of the paper recent results on the structure of point sets having few 0-secant subspaces are discussed. Our attention is focussed on the planar case, where various stability results are given.