Evaluation of left ventricular systolic asynchrony in patients with subclinical hypothyroidism

Background: The heart was very sensitive to fluctuating thyroid hormone levels. To assess intra-left ventricular (LV) systolic asynchrony in patients with subclinical thyroid dysfunction. Methods: Fifty patients with subclinical hypothyroidism and 40 controls were included. A diagnosis of subclinical hypothyroidism was reached with increased TSH and normal free T4. All subjects were evaluated by echocardiography. Evaluation of intra-LV systolic asynchrony was performed by tissue synchronization imaging (TSI), and four TSI parameters of systolic asynchrony were calculated. LV asynchrony was defined by these parameters. Results: All of the groups were similar in terms of demographic findings and conventional and Doppler echocardiograpic parameters except peak systolic velocity and early diastolic velocity. LV systolic asynchrony parameters of TSI including; standard deviation of Ts of the 12 LV segments (Ts-SD-12), maximal difference in Ts between any 2 of the 12 LV segments (Ts-12), standard deviation of TS of the 6 basal LV segments (Ts-SD-6), maximal difference in Ts between any of the 6 basal LV segments (Ts-6) were significantly lengthened in patients with subclinical hypothyroidism than controls (p < 0.001, p < 0.001, p < 0.001 and p < 0.001, respectively). The prevalence of LV asynchrony was significantly higher in patients with subclinical hypothyroidism than control. Conclusions: Patients with subclinical hypothyroidism present evidence of LV asynchrony by TSI. LV systolic asynchrony could be a warning sign of the early stage in cardiac systolic dysfunction in subclinical hypothyroid patients

Evaluation of left atrial mechanical functions and atrial conduction abnormalities in patients with clinical hypothyroid

Background: The aim of this study was to investigate left atrial (LA) mechanical functions, atrial electromechanical delay and P wave dispersion in hypothyroid patients. Methods: Thirty-four patients with overt hypothyroid and thirty controls were included. A diagnosis of overt hypothyroid was reached with increased serum TSH and decreased free T4 (fT4) levels. LA volumes were measured using the biplane area length method and LA active and passive emptying volumes and fraction were calculated. Intra- and interatrial electromechanical delay (EMD) were measured by tissue Doppler imaging (TDI). P wave dispersion was calculated by 12 lead electrocardiograms. Results: LA diameter were significantly higher in patients with overt hypothyroid (p = 0.021). LA passive emptying volume and LA passive emptying fraction were significantly decreased with hypothyroid patients (p = 0.002 and p < 0.001). LA active emptying volume and LA active emptying fraction were significantly increased with hypothyroid patients (p < 0.001 and p < 0.001). Intra- and interatrial EMD, were measured significantly higher in hypothyroid patients (30.6 &#177; 6.1 vs 18.0 &#177; 2.7, p < 0.001; and 10.6 &#177; 3.4 vs 6.9 &#177; 1.4, p < 0.001, respectively). P wave dispersion were significantly higher in hypothyroid patients (48.8 &#177; 6.2 vs 44.3 &#177; 7.2, p = 0.022). In stepwise regression analysis demonstrated that, interatrial EMD and LA active emptying fraction related with TSH and fT4. Conclusions: This study showed that impaired LA mechanical and electromechanical function in hypothyroid patients. TSH and T4 were independent determinant of interatrial EMD and LA active emptying fraction

Ocena zaburzeń przewodzenia przedsionkowego i czynności mechanicznej lewego przedsionka u chorych z subklinicznymi zaburzeniami czynności tarczycy

Introduction: Changes of thyroid hormones levels may lead to effects, not only in ventricular function, but also atrial function. The aim of this study was to investigate left atrial (LA) mechanical functions, atrial electromechanical coupling and P wave dispersion in patients with subclinical thyroid disorders. Material and methods: Eighty patients with subclinical thyroid disorders and forty controls were included. A diagnosis of subclinical thyroid disorders were reached with increased or decreased serum TSH and normal free T4 (fT4) levels. LA volumes were measured using the biplane area length method and LA active and passive emptying volumes and fraction were calculated. Intra- and interatrial electromechanical delay were measured by tissue Doppler imaging (TDI). Results: All groups had similar demographic findings. LA mechanical functions significantly impaired in subclinical thyroid disorders than control group. Intra- and Interatrial delay, were measured significantly higher in patients with subclinical thyroid disorders than control group. PA lateral and interatrial delay were positively correlated with TSH (r = 0.507, p = 0.006 and r = 0.455, p = 0.015, respectively) in subclinical hypothyroid patients. There was negative correlation between TSH and interatrial delay (r = &#8211;0.492, p = 0.006) in subclinical hyperthyroid patients. Linear multivariate regression analysis demonstrated that, TSH was the only an independent factor of interatrial delay in patients with subclinica tlhyroid disorders. Conclusions: This study showed that impaired LA mechanical and electromechanical function in subclinical thyroid disorders. TSH was an independent determinant of interatrial delay. Prolonged atrial electromechanical coupling time and impaired mechanical atrial functions may be related to the increased incidence of arrhythmias.Wstęp: Zmiany stężeń hormonów tarczycy mogą wpływać nie tylko na czynność komór serca, ale również na czynność przedsionków. Niniejsze badanie przeprowadzono w celu oceny czynności mechanicznej lewego przedsionka (LA), sprzężenia elektromechanicznego i dyspersji załamka P u chorych z subklinicznymi zaburzeniami czynności tarczycy. Materiał i metody: Do badania włączono 80 chorych z subklinicznymi zaburzeniami czynności tarczycy i 40 osób stanowiących grupę kontrolną. Zaburzenia czynności tarczycy rozpoznawano na podstawie obniżonego lub podwyższonego stężenia TSH w surowicy i prawidłowego stężenia wolnej T4 (fT4). Zmierzono objętości LA, posługując się dwupłaszczyznową metodą area-lenght (pole&#8211; wymiar podłużny). Obliczono również objętości i frakcje aktywnego i biernego opróżniania LA. Do pomiaru opóźnienia przewodnictwa wewnątrzi międzyprzedsionkowego zastosowano technikę doplera tkankowego. Wyniki: Grupy nie różniły się pod względem charakterystyki demograficznej. W grupie z zaburzeniami czynności tarczycy mechaniczna funkcja przedsionków była istotnie upośledzona w porównaniu z osobami z grupy kontrolnej. Opóźnienie przewodnictwa wewnątrzi międzyprzedsionkowego stwierdzano istotnie częściej u osób z zaburzeniami czynności tarczycy. Stwierdzono dodatnią korelację miedzy opóźnieniem elektromechanicznym (PA lateral) i opóźnieniem przewodzenia międzyprzedsionkowego a TSH (odpowiednio r = 0,507; p = 0,006 i r = 0,455; p = 0,015) u osób z subkliniczną niedoczynnością tarczycy. Z kolei u osób z subkliniczną nadczynnością tarczycy zaobserwowano ujemną korelację między TSH i opóźnieniem przewodzenia międzyprzedsionkowego (r = &#8211;0,492; p = 0,006). W wieloczynnikowej analizie regresji liniowej wykazano, że stężenie TSH było jedynym parametrem niezależnie związanym z opóźnieniem przewodzenia międzyprzedsionkowego u chorych z subklinicznymi zaburzeniami czynności tarczycy. Wnioski: W niniejszym badaniu wykazano upośledzoną czynność mechaniczną i elektromechaniczną LA u chorych z subklinicznymi zaburzeniami czynności tarczycy. Stężenie TSH było niezależnym czynnikiem determinującym opóźnienie przewodzenia międzyprzedsionkowego. Wydłużenie czasu sprzężenia elektromechanicznego i upośledzenie mechanicznej czynności przedsionków mogą się wiązać ze zwiększoną zapadalnością na zaburzenia rytmu

Simplified Numerical Approach for the Prediction of Aerodynamic Forces on Grid Fins

Grid fins are unconventional control devices used for aerodynamic control of various types of missiles. Low hinge moment requirement and superior packaging potential make grid fins attractive alternatives to conventional planar fins. Unlike missiles with planar fins, widely accepted preliminary design tools for missiles with grid fins are not available. As an alternative, aerodynamic forces and moments are obtained through full computational fluid dynamics solutions. However, generating an aerodynamic force and moment database in the preliminary design stage using full computational fluid dynamics solutions takes too much time due to the complex geometry of grid fins and the corresponding mesh requirements. In this study, the unit grid fin concept, which is a small representative portion of a grid fin, is introduced for the efficient prediction of flows around missiles with grid fin controls. The study is conducted at Mach numbers of 0.7, 1.2, and 2.5 in an angle-of-attack range between 0 and 15deg. First, the validation of the proposed technique is done for side fins in the + configuration, for which there are available experimental data. Then, the idea is applied for the simulation of the more common x configuration. It is shown that, although requiring much less computational resources and time as compared to a full computational fluid dynamics solution, the unit grid fin approach can provide acceptable results for preliminary design. The body interference correction turns out to be critical in the performance of the proposed method, and the deficiency of a simple potential flow-based approach is demonstrated

The Influence of Scale Resolving Simulations in Predictions of Vortex Interaction about a Generic Missile Airframe

Hybrid Reynolds Average Navier-Stokes (RANS) - Large Eddy Simulations (LES) have been applied to predict the rolling moment coefficient of a generic missile at high angle of incidence in supersonic flow. The missile airframe was rolled which generated unsymmetrical vortices affecting the downstream tail fin section. Traditional RANS indicated difficulties predicting the rolling moment. This challenge was accepted by the NATO Science and Technology Organization (STO), Applied Vehicle Technology (AVT) panel forming a devoted Task Group AVT-316 “Vortex Interaction Effects Relevant To Military Air Vehicle Performance”. The paper describes the Missile Facets work on scale resolving simulations with spatial and temporal resolution strategy, quality index for LES and comparison with industry standard RANS methods. The hybrid RANS-LES results provided additional insights into the nature of the complex vortex interactions, including shocks, associated with slender body aerodynamics not detected with RANS. Scale resolving simulations drastically reduced vortex dissipation and resulted in significant shift of rolling moment magnitude

Simplified Numerical Approach for the Prediction of Aerodynamic Forces on Grid Fins

Grid fins are unconventional control devices used for aerodynamic control of various types of missiles. Low hinge moment requirement and superior packaging potential make grid fins attractive alternatives to conventional planar fins. Unlike missiles with planar fins, widely accepted preliminary design tools for missiles with grid fins are not available. As an alternative, aerodynamic forces and moments are obtained through full computational fluid dynamics solutions. However, generating an aerodynamic force and moment database in the preliminary design stage using full computational fluid dynamics solutions takes too much time due to the complex geometry of grid fins and the corresponding mesh requirements. In this study, the unit grid fin concept, which is a small representative portion of a grid fin, is introduced for the efficient prediction of flows around missiles with grid fin controls. The study is conducted at Mach numbers of 0.7, 1.2, and 2.5 in an angle-of-attack range between 0 and 15deg. First, the validation of the proposed technique is done for side fins in the + configuration, for which there are available experimental data. Then, the idea is applied for the simulation of the more common x configuration. It is shown that, although requiring much less computational resources and time as compared to a full computational fluid dynamics solution, the unit grid fin approach can provide acceptable results for preliminary design. The body interference correction turns out to be critical in the performance of the proposed method, and the deficiency of a simple potential flow-based approach is demonstrated

Comparisons of Predicted and Measured Aerodynamic Characteristics of the DLR LK6E2 Missile Airframe

In this study, the influence of the turbulence model, grid resolution and flow solvers on the results of RANS simulations is investigated. The work is part of the NATO AVT Task Group AVT-316 (Vortex Interaction Effects Relevant to Military Air Vehicle Performance). Simulations have been carried out for a generic transonic missile configuration by various organizations and compared with data from wind tunnel experiments for a Mach number of M = 0.85, a roll angle of $\boldsymbol{45^\circ}$ and total incidences in the range of $\boldsymbol{15^\circ\leq\sigma\leq17.5^\circ}$. In the first part of the study each organization used their own computational mesh and best practice for the grid generation. In the second part a common mesh family (three grids) were used for the simulations. It was shown that even for the common mesh family, the results of the different flow solvers in some cases showed large variations. This applies in particular to the rolling moment. Here, the accurate flow solver-dependent prediction of the complicated flow topology on the large wings and the accurate prediction of the location of the leeward vortices have a particularly strong effect. Only one flow solver predicted this flow in a form that gave good agreement with the wind tunnel results over the entire investigated angular range

The Influence of the Computational Mesh on the Prediction of Vortex Interactions about a Generic Missile Airframe

A research program has been underway for four years to study vortex interaction aerodynamics that are relevant to military air vehicle performance. The program has been conducted under the auspices of the NATO Science and Technology Organization (STO), Applied Vehicle Technology (AVT) panel by a Task Group with the identification of AVT-316. The Missile Facet of this group has concentrated their work on the vortical flow field around a generic missile airframe and its prediction via computational methods. This paper focuses on mesh-related effects and RANS simulations. Simulated vortex characteristics were found to depend strongly on the properties of the employed mesh, in terms of both resolution and topology. Predictions of missile aerodynamic coefficients show a great dependence on mesh properties as they are sensitive to computed vortex dynamics. Key suggestions about the desired mesh characteristics have been made. Based on these, a shared mesh was constructed to perform common analyses between the AVT-316 Missile Facet members. Mesh based uncertainties of the aerodynamic coefficient predictions were estimated via Richardson Extrapolation method