Acute Beneficial Hemodynamic Effects of a Novel 3D-Echocardiographic Optimization Protocol in Cardiac Resynchronization Therapy

Post-implantation therapies to optimize cardiac resynchronization therapy (CRT) focus on adjustments of the atrio-ventricular (AV) delay and ventricular-to-ventricular (VV) interval. However, there is little consensus on how to achieve best resynchronization with these parameters. The aim of this study was to examine a novel combination of doppler echocardiography (DE) and three-dimensional echocardiography (3DE) for individualized optimization of device based AV delays and VV intervals compared to empiric programming.25 recipients of CRT (male: 56%, mean age: 67 years) were included in this study. Ejection fraction (EF), the primary outcome parameter, and left ventricular (LV) dimensions were evaluated by 3DE before CRT (baseline), after AV delay optimization while pacing the ventricles simultaneously (empiric VV interval programming) and after individualized VV interval optimization. For AV delay optimization aortic velocity time integral (AoVTI) was examined in eight different AV delays, and the AV delay with the highest AoVTI was programmed. For individualized VV interval optimization 3DE full-volume datasets of the left ventricle were obtained and analyzed to derive a systolic dyssynchrony index (SDI), calculated from the dispersion of time to minimal regional volume for all 16 LV segments. Consecutively, SDI was evaluated in six different VV intervals (including LV or right ventricular preactivation), and the VV interval with the lowest SDI was programmed (individualized optimization).EF increased from baseline 23±7% to 30±8 (p<0.001) after AV delay optimization and to 32±8% (p<0.05) after individualized optimization with an associated decrease of end-systolic volume from a baseline of 138±60 ml to 115±42 ml (p<0.001). Moreover, individualized optimization significantly reduced SDI from a baseline of 14.3±5.5% to 6.1±2.6% (p<0.001).Compared with empiric programming of biventricular pacemakers, individualized echocardiographic optimization with the integration of 3-dimensional indices into the optimization protocol acutely improved LV systolic function and decreased ESV and can be used to select the optimal AV delay and VV interval in CRT

Word Processing differences between dyslexic and control children

BACKGROUND: The aim of this study was to investigate brain responses triggered by different wordclasses in dyslexic and control children. The majority of dyslexic children have difficulties to phonologically assemble a word from sublexical parts following grapheme-to-phoneme correspondences. Therefore, we hypothesised that dyslexic children should mainly differ from controls processing low frequent words that are unfamiliar to the reader. METHODS: We presented different wordclasses (high and low frequent words, pseudowords) in a rapid serial visual word (RSVP) design and performed wavelet analysis on the evoked activity. RESULTS: Dyslexic children had lower evoked power amplitudes and a higher spectral frequency for low frequent words compared to control children. No group differences were found for high frequent words and pseudowords. Control children had higher evoked power amplitudes and a lower spectral frequency for low frequent words compared to high frequent words and pseudowords. This pattern was not present in the dyslexic group. CONCLUSION: Dyslexic children differed from control children only in their brain responses to low frequent words while showing no modulated brain activity in response to the three word types. This might support the hypothesis that dyslexic children are selectively impaired reading words that require sublexical processing. However, the lacking differences between word types raise the question if dyslexic children were able to process the words presented in rapid serial fashion in an adequate way. Therefore the present results should only be interpreted as evidence for a specific sublexical processing deficit with caution

Which training is the most effective for children with dyslexia? Effects on the ability of reading and spelling and the functional organisation of language in the brain

The purpose of this study was to examine the effectiveness of three different trainings for 3rd and 4th grade children with dyslexia. Each training is based on a different etiological theory. The improvement of reading and spelling should be emphasized either by improvement of the phonological awareness (rythmic training with syllables, following Buschmann (1988)), or by improvement of the temporal processing (auditory perception training with a PC), or by learning cognitive strategies and rules. Before and after the training phase the children took standardized and nonstandardized tests of reading and spelling, phonological processing, categorical perception and nonverbal intelligence (SPM).The cortical language processing was examined by means of magnetoencephalography. The mismatch field (MMF) and the localisation of dipols by auditory presentation of syllables were measured and a time-frequency-band analysis was computed by short visual presented high and low frequent words and pseudo-words (duration of presentation: 350ms, ISI: 0ms; Fast Words ).22 controls without dyslexia and 64 children with dyslexia participated in the study. The children with dyslexia were randomly allocated for the different trainings, which lasted for 5 weeks.Before the training the control-group was in all behavioral measures significantly better than the dyslexia-group. This includes a phonological processing deficit for the dyslexia-group, but there was no hint for a deficit in the temporal processing, since there were no differences in the MMF-amplitude. The source-localisation of the N260 in response of the syllable /ba/ was symmetrically distributed for the dyslexia-group, while the control-group showed the typical asymmetric dipol-distribution with the dipol in the right hemisphere being significantly more anterior than in the left hemisphere. There were significant differences betwen the two groups in the maximum amplitude of evoked power as well as in the spectral frequencies. This means a missing activation of phonological processes or a phonological processing deficit respectively.After the training all training-groups improved significantly in the spelling-test (DRT), while there was no improvement in the reading and phonological processing tests. Since there were no differential training effects and no improvements of the phonological processing, it is impossible to draw any conclusion about the etiology of dyslexia. However the rhythmic-syllabic training (following Buschmann, 1988) seems to be the most effective, since the effect was the same with only the half of training time in comparison to the other trainings. Concerning the MEG-parameters only the MMF-amplitude was increased for two groups: in the left hemisphere for the temporal-processing-training group and in the right hemisphere for the rhythmic-syllabic-training group. But even if you take these improvements as a possible measure for an improved temporal processing they do not correlate with the improved spelling-ability.With this study it was possible to show phonological processing deficits in behavioral and cortical measures. However since there were no differential training effects, it is impossible to conclude a causal connection between this phonological deficit and dyslexia

Reduced hemispheric asymmetry of the auditory N260m in dyslexia

Dyslexia seems to be related to a lack of planum temporale (PT) asymmetry that is accompanied by functional differences to control subjects in both left and right hemispheric temporal regions during language tasks. PT asymmetry has been found to correlate with phonological and verbal skills. In accordance, reduced asymmetry of the auditory N100m sources in dyslexic adults and P100m sources in dyslexic children has been reported. These results might also be related to an atypical PT symmetry or the recruitment of other structures than the PT for speech processing in dyslexia. In the present study we tried to replicate and extend previous findings by examining a sample of 64 dyslexic and 22 control children in the MEG. We measured cortical activity during a passive auditory oddball-paradigm and localised ERF sources evoked by the standard stimulus /ba/. Reduced hemispheric asymmetry in the localisation of the auditory N260m was revealed. While control children displayed a typical asymmetrical pattern with more anterior sources in the right hemisphere, this asymmetry was not present for the dyslexic children. Further, a correlation between N260m asymmetry and spelling test performance was found. Our results suggest that localisation of ERF components is indeed an applicative tool for investigating cortical deviances in dyslexia. A lack of source localisation asymmetry in dyslexia appears to be a robust finding across different samples of dyslexic children and adults. It appears that cortical auditory (language) processing is organised differently in dyslexic subjects than in controls. This might be the consequence of a more symmetrical PT organisation, which in turn might be the result of maturational delay

Phonological but not auditory discrimination is impaired in dyslexia

Deficient phonological skills are considered to be a core problem in developmental dyslexia. Children with dyslexia often demonstrate poorer performance than non-impaired readers when categorizing speech-sounds. Using the automatic mismatch response, we show that in contrast to this deficit at the behavioural level, neurophysiological responding in dyslexic children indicates their ability to automatically discriminate syllables. Therefore, the phonological deficit is unlikely to be caused by a temporal deficit or by a noisy functional organization in the respective representational cortex. We obtained measures of reading, spelling and categorical speechperception from 58 dyslexic children and 21 control children. The children also participated in magnetoencephalographic measurements while being stimulated acoustically with the syllables /ba/ and /da/ in an oddball paradigm. Mismatch field (MMF) amplitudes between standard and deviant stimuli were obtained. Dyslexic children performed more poorly than control children on all test measures. However, the groups did not differ in MMF amplitude or latency. No correlations were found between MMF amplitudes and behavioural performance.These results were obtained with a large sample size and thus speak robustly against a general deficit in auditory discrimination in dyslexia. These results are compatible with the idea that decoding difficulties occur later in the processing stream where access to the phonological lexicon is attempted

Dzyaloshinskii-Moriya interaction and the magnetic ground state in magnetoelectric LiCoPO₄

Magnetic structures are investigated by means of neutron diffraction to shine a light on the intricate details that are believed to be key to understanding the magnetoelectric effect in LiCoPO$_4$ . At zero field, a spontaneous spin canting of $\varphi = 7(1)^{\circ}$ is found. The spins tilt away from the easy $b$-axis toward $c$. Symmetry considerations lead to the magnetic point group $m'_z$, which is consistent with the previously observed magnetoelectric tensor form and weak ferromagnetic moment along $b$. For magnetic fields applied along $a$, the induced ferromagnetic moment couples via the Dzyaloshinskii-Moriya interaction to yield an additional field-induced spin canting. An upper limit to the size of the interaction is estimated from the canting angle

Baseline characteristics.

<p>Values are shown as means ± standard deviation or count (percentage).</p><p>NYHA, New York Heart Association; CMP, cardiomyopathy; ACE, Angiotensin-converting enzyme; ARB, Angiotensin receptor blocker; LV, left ventricle; SDI, systolic dyssynchrony index.</p

Echocardiographic parameters at baseline and after AV delay and VV interval optimization.

<p>SDI, systolic dyssynchrony index; AV, atrio-ventricular; VV, ventriculo-ventricular; LV, left ventricular; VTI, velocity-time integral.</p><p>Shown are means ± standard deviation.</p>†<p>p<0.001: for comparison of AV optimization vs baseline.</p>¶<p>p<0.05: for comparison of complete optimization vs AV optimization only.</p><p>*p<0.05: for comparison of complete optimization vs baseline.</p

Ventricular-to-ventricular (VV) intervals in patients with ischemic and dilated cardiomyopathy.

<p>Number of patients with simultaneous activation of left and right ventricle or sequential inter-ventricular pacing depending on ischemic or dilated cardiomyopathy.</p