Electro-mechanical dysfunction in long QT syndrome: Role for arrhythmogenic risk prediction and modulation by sex and sex hormones.

Long QT syndrome (LQTS) is a congenital arrhythmogenic channelopathy characterized by impaired cardiac repolarization. Increasing evidence supports the notion that LQTS is not purely an "electrical" disease but rather an "electro-mechanical" disease with regionally heterogeneously impaired electrical and mechanical cardiac function. In the first part, this article reviews current knowledge on electro-mechanical (dys)function in LQTS, clinical consequences of the observed electro-mechanical dysfunction, and potential underlying mechanisms. Since several novel imaging techniques - Strain Echocardiography (SE) and Magnetic Resonance Tissue Phase Mapping (TPM) - are applied in clinical and experimental settings to assess the (regional) mechanical function, advantages of these non-invasive techniques and their feasibility in the clinical routine are particularly highlighted. The second part provides novel insights into sex differences and sex hormone effects on electro-mechanical cardiac function in a transgenic LQT2 rabbit model. Here we demonstrate that female LQT2 rabbits exhibit a prolonged time to diastolic peak - as marker for contraction duration and early relaxation - compared to males. Chronic estradiol-treatment enhances these differences in time to diastolic peak even more and additionally increases the risk for ventricular arrhythmia. Importantly, time to diastolic peak is particularly prolonged in rabbits exhibiting ventricular arrhythmia - regardless of hormone treatment - contrasting with a lack of differences in QT duration between symptomatic and asymptomatic LQT2 rabbits. This indicates the potential added value of the assessment of mechanical dysfunction in future risk stratification of LQTS patients.

Details of left ventricular radial wall motion supporting the ventricular theory of the third heart sound obtained by cardiac MR.

OBJECTIVE: Obtaining new details of radial motion of left ventricular (LV) segments using velocity-encoding cardiac MRI. METHODS: Cardiac MR examinations were performed on 14 healthy volunteers aged between 19 and 26 years. Cine images for navigator-gated phase contrast velocity mapping were acquired using a black blood segmented κ-space spoiled gradient echo sequence with a temporal resolution of 13.8 ms. Peak systolic and diastolic radial velocities as well as radial velocity curves were obtained for 16 ventricular segments. RESULTS: Significant differences among peak radial velocities of basal and mid-ventricular segments have been recorded. Particular patterns of segmental radial velocity curves were also noted. An additional wave of outward radial movement during the phase of rapid ventricular filling, corresponding to the expected timing of the third heart sound, appeared of particular interest. CONCLUSION: The technique has allowed visualization of new details of LV radial wall motion. In particular, higher peak systolic radial velocities of anterior and inferior segments are suggestive of a relatively higher dynamics of anteroposterior vs lateral radial motion in systole. Specific patterns of radial motion of other LV segments may provide additional insights into LV mechanics. ADVANCES IN KNOWLEDGE: The outward radial movement of LV segments impacted by the blood flow during rapid ventricular filling provides a potential substrate for the third heart sound. A biphasic radial expansion of the basal anteroseptal segment in early diastole is likely to be related to the simultaneous longitudinal LV displacement by the stretched great vessels following repolarization and their close apposition to this segment.

Effects of ventricular insertion sites on rotational motion of left ventricular segments studied by cardiac MR.

OBJECTIVE: Obtaining new details for rotational motion of left ventricular (LV) segments using velocity encoding cardiac MR and correlating the regional motion patterns to LV insertion sites. METHODS: Cardiac MR examinations were performed on 14 healthy volunteers aged between 19 and 26 years. Peak rotational velocities and circumferential velocity curves were obtained for 16 ventricular segments. RESULTS: Reduced peak clockwise velocities of anteroseptal segments (i.e. Segments 2 and 8) and peak counterclockwise velocities of inferoseptal segments (i.e. Segments 3 and 9) were the most prominent findings. The observations can be attributed to the LV insertion sites into the right ventricle, limiting the clockwise rotation of anteroseptal LV segments and the counterclockwise rotation of inferoseptal segments as viewed from the apex. Relatively lower clockwise velocities of Segment 5 and counterclockwise velocities of Segment 6 were also noted, suggesting a cardiac fixation point between these two segments, which is in close proximity to the lateral LV wall. CONCLUSION: Apart from showing different rotational patterns of LV base, mid ventricle and apex, the study showed significant differences in the rotational velocities of individual LV segments. Correlating regional wall motion with known orientation of myocardial aggregates has also provided new insights into the mechanisms of LV rotational motions during a cardiac cycle. ADVANCES IN KNOWLEDGE: LV insertion into the right ventricle limits the clockwise rotation of anteroseptal LV segments and the counterclockwise rotation of inferoseptal segments adjacent to the ventricular insertion sites. The pattern should be differentiated from wall motion abnormalities in cardiac pathology.

[Change and innovation in orthodontics]. / Wandel und Innovation in der Kieferorthopädie.

Long-term prophylaxis achievements, demographic changes, scientific progress, patient requirements, and political regulations through social legislation will fundamentally change the future of orthodontics, i.e., a reduction in children and adolescent therapy as well as an increase in interdisciplinary complex treatments for adult patients mostly outside the social security system. Health care research at a high evidence level needs to be intensified due to social-political reasons. In addition to well-proven appliances, modern sometimes even invisible appliances (CAD-CAM) will be used in future orthodontic therapy. Three-dimensional diagnostics could improve treatment planning. Whether improved prenatal diagnosis will alter the number of newborns with dentofacial malformations (cleft lip and palate) or syndromes (e.g., Down syndrome), thus, changing treatment needs in the future, cannot be predicted today, due to the multiple influencing factors. A well-structured 4-year specialist training according to European guidelines will also be necessary in the future to comply with complex treatment needs be it within or outside the social security system (quality assurance).

Uprighting and distalisation of first permanent maxillary molars in patients with undermining resorption: a case report.

AIM: This case report describes a treatment method for distalisation and uprighting of first permanent maxillary molars with the aim of preventing complications in the presence of undermining resorption of the second deciduous molar. We present a fixed appliance, which is a compliance-independent and effective alternative to the methods used thus far such as removable plates with distal screws or separating ligatures.

The effect of reconstruction and acquisition parameters for GRAPPA-based parallel imaging on the image quality.

Parallel imaging based on generalized autocalibrating partially parallel acquisitions is widely used in the clinical routine. To date, no detailed analysis has been presented describing the dependence of the image quality on the reconstruction and acquisition parameters such as the number of autocalibration signal (ACS) lines NACS, the reconstruction kernel size (bx×by), and the undersampling factor R. To evaluate their influence on the performance of generalized autocalibrating partially parallel acquisitions, two phantom data sets acquired with 12-channel and 32-channel receive coils and three in vivo measurements were analyzed. Reconstruction parameters were systematically varied between R=2-4, NACS=4-64, bx=1-9, and by=2-10 to characterize their influence on image quality and noise. A main aspect of the analysis was to optimize the parameter set with respect to the effectively achieved net image acceleration. Selecting the undersampling factor R as small as possible for a given net acceleration yielded the best result in a clear majority of cases. For all data sets and coil geometries, the optimal kernel sizes and number of ACS lines were similar for a chosen undersampling factor R. In summary, the number of ACS lines should not be chosen below NACS=10-16. A robust choice for the kernel size was bx=9 and by=2-4.

Multiple sclerosis: etiology and epidemiology.

Multiple sclerosis (MS) is a demyelinating, auto-immune disease which affect the central nervous system. The research seems to implicate a small or incomplete slow-growing virus as the causative agent. The measles virus has been suspected because of high titers of measles antibodies in MS patients' serum and cerebrospinal fluid. An immunological deficiency in MS patients may be linked to genetic factors such as HL-A tissue types and histocompatibility antigens. Genetics and socioeconomic conditions may also result in the distinct geographical pattern of MS distribution in the world.