Twist Values Research Articles

Rational frames of minimal twist along space curves under specified boundary conditions

An adapted orthonormal frame (f1(ξ),f2(ξ),f3(ξ)) on a space curve r(ξ), ξ ∈ [ 0, 1 ] comprises the curve tangent $\mathbf {f}_{1}(\xi ) =\mathbf {r}^{\prime }(\xi )/|\mathbf {r}^{\prime }(\xi )|$ and two unit vectors f2(ξ),f3(ξ) that span the normal plane. The variation of this frame is specified by its angular velocity Ω = Ω1f1 + Ω2f2 + Ω3f3, and the twist of the framed curve is the integral of the component Ω1 with respect to arc length. A minimal twist frame (MTF) has the least possible twist value, subject to prescribed initial and final orientations f2(0),f3(0) and f2(1),f3(1) of the normal–plane vectors. Employing the Euler–Rodrigues frame (ERF) — a rational adapted frame defined on spatial Pythagorean–hodograph curves — as an intermediary, an exact expression for an MTF with Ω1 = constant is derived. However, since this involves rather complicated transcendental terms, a construction of rational MTFs is proposed by the imposition of a rational rotation on the ERF normal–plane vectors. For spatial PH quintics, it is shown that rational MTFs compatible with the boundary conditions can be constructed, with only modest deviations of Ω1 about the mean value, by a rational quartic normal–plane rotation of the ERF. If necessary, subdivision methods can be invoked to ensure that the rational MTF is free of inflections, or to more accurately approximate a constant Ω1. The procedure is summarized by an algorithm outline, and illustrated by a representative selection of computed examples.

Twist effects in quantum vortices and phase defects

In this paper we show that twist, defined in terms of rotation of the phase associated with quantum vortices and other physical defects effectively deprived of internal structure, is a property that has observable effects in terms of induced axial flow. For this we consider quantum vortices governed by the Gross–Pitaevskii equation (GPE) and perform a number of test cases to investigate and compare the effects of twist in two different contexts: (i) when this is artificially superimposed on an initially untwisted vortex ring; (ii) when it is naturally produced on the ring by the simultaneous presence of a central straight vortex. In the first case large amplitude perturbations quickly develop, generated by the unnatural setting of the initial condition that is not an analytical solution of the GPE. In the second case much milder perturbations emerge, signature of a genuine physical process. This scenario is confirmed by other test cases performed at higher twist values. Since the second setting corresponds to essential linking, these results provide new evidence of the influence of topology on physics.

Can elastic constants and surface alignment be obtained from polarized microscopy images of nematic droplets? A Monte Carlo study

We present a Monte Carlo study of the effects of elastic anisotropy on the textures of nematic droplets with different boundary conditions. Simulated polarized optical microscopy (POM) images are analysed for uniaxial nematics with radial, bipolar and toroidal boundaries and for numerous combinations of the splay, twist and bend elastic constant values. An atlas of simulated textures is presented as an aid to understanding new experimental results.

Contribution of Field Strength Gradients to the Net Vertical Current of Active Regions

Abstract We examined the contribution of field strength gradients for the degree of net vertical current (NVC) neutralization in active regions (ARs). We used photospheric vector magnetic field observations of AR 11158 obtained by Helioseismic and Magnetic Imager on board SDO and Hinode. The vertical component of the electric current is decomposed into twist and shear terms. The NVC exhibits systematic evolution owing to the presence of the sheared polarity inversion line between rotating and shearing magnetic regions. We found that the sign of shear current distribution is opposite in dominant pixels (60%–65%) to that of twist current distribution, and its time profile bears no systematic trend. This result indicates that the gradient of magnetic field strength contributes to an opposite signed, though smaller in magnitude, current to that contributed by the magnetic field direction in the vertical component of the current. Consequently, the net value of the shear current is negative in both polarity regions, which when added to the net twist current reduces the direct current value in the north (B z > 0) polarity, resulting in a higher degree of NVC neutralization. We conjecture that the observed opposite signs of shear and twist currents are an indication, according to Parker, that the direct volume currents of flux tubes are canceled by their return currents, which are contributed by field strength gradients. Furthermore, with the increase of spatial resolution, we found higher values of twist, shear current distributions. However, the resolution effect is more useful in resolving the field strength gradients, and therefore suggests more contribution from shear current for the degree of NVC neutralization.

Echocardiographic evaluation of left ventricle mechanical parameters in infants of the first year of life

Aim. The study focused on the analysis of the measurement range of left ventricle mechanics (strain, strain rate, rotation, rotation rate, twisting, untwisting, torsion) in healthy infants of the first year of life to obtain their baseline values.Methods. The study included 125 healthy infants aged 5 days to 12 months (average 5.9±3.9 months. The Аcuson S 2000 machine (Siemens Medical Systems, Mountain View, CA, USA) was used to perform echocardiography. The indicators of left ventricle longitudinal strain (%) and strain rate (s–1), radial strain and strain rate (% and s–1), circumferential strain and strain rate (% and s–1), basal and apical rotation in systole and diastole (°) and rotation rate (°/s), twisting (°), untwisting (°), twisting and unwinding rate (°/s) and torsion (°/cm) were measured and analyzed. Results. It was found out that the values of the longitudinal strain and strain rate inversely correlate with the pumping function (stroke volume index) and diastolic function (filling pressures and the untwisting rate). The parameters of the circular and radial strain tended to depend on the left ventricle mass index, interventricular septum/left ventricle posterior wall thicknesses. Left ventricle twisting and untwisting would increase in healthy infants from the newborn period to the first year of life. Left ventricle torsion range was determined by the twist values and not by left ventricular geometry.Conclusion. The obtained data on the values of longitudinal, circumferential and radial left ventricle strain and strain rate can be used as reference ranges to evaluate the mechanical left ventricular function in infants of the first year of life. Received 27 January 2017. Accepted 15 June 2017. Funding: The study did not have sponsorship. Conflict of interest: The authors declare no conflict of interest. Author contributionsConception and study design: Yu.S. Sinelnikov, E.N. OrekhovaData collection and analysis: M.A. Polevshikova, T.V. Matanovskaya Drafting the article: E.N. Orekhova, M.A. PolevshikovaCritical revision of the article: Yu.S. Sinelnikov, E.N. OrekhovaFinal approval of the version to be published: Yu.S. Sinelnikov, E.N. Orekhova, T.V. Matanovskaya, M.A. Polevshikova

Energetics of the Kelvin-Helmholtz instability induced by transverse waves in twisted coronal loops

Aims: We quantify the effects of twisted magnetic fields on the development of the magnetic Kelvin-Helmholtz instability (KHI) in transversely oscillating coronal loops. Methods: We modelled a fundamental standing kink mode in a straight, density-enhanced magnetic flux tube using the magnetohydrodynamics code, Lare3d. In order to evaluate the impact of an azimuthal component of the magnetic field, various degrees of twist were included within the flux tube's magnetic field. Results: The process of resonant absorption is only weakly affected by the presence of a twisted magnetic field. However, the subsequent evolution of the KHI is sensitive to the strength of the azimuthal component of the field. Increased twist values inhibit the deformation of the loop's density profile, which is associated with the growth of the instability. Despite this, much smaller scales in the magnetic field are generated when there is a non-zero azimuthal component present. Hence, the instability is more energetic in cases with (even weakly) twisted fields. Field aligned flows at the loop apex are established in a twisted regime once the instability has formed. Conclusions: The KHI may have implications for wave heating in the solar atmosphere due to the creation of small length scales and the generation of a turbulent regime. Whilst magnetic twist does suppress the development of the vortices associated with the instability, the formation of the KHI in a twisted regime will be accompanied by greater Ohmic dissipation due to the larger currents that are produced, even if only weak twist is present. The presence of magnetic twist will likely make the instability more difficult to detect in the corona, but will enhance its contribution to heating the solar atmosphere.

Assessment of left ventricular performance in heart transplant recipients by three-dimensional speckle tracking imaging.

To calculate left ventricular (LV) global performance values in heart transplant (HT) recipients by three-dimensional speckle tracking imaging (3D-STI) and to observe the changes in LV global performance over time after HT and investigate the correlated factors.The 30 HT patients were divided into 2 groups according to postoperative time: 1 month postoperatively (HT-1) group and 6 months postoperatively (HT-2) group. Thirty healthy subjects were enrolled as control group. 3D-STI was performed to assess LV torsion, LV systolic dyssynchrony index (SDI), and LV global strain (GS). Global performance index (GPI) was calculated, and correlations factors with GPI were studied.Heart rate (HR), left atrium (LA), interventricular septum thickness (IVST), left ventricular posterior wall thickness (LVPWT), and left ventricular mass (LVM) in both HT groups were higher than those in the control group. Compared with the control group, SDI was significantly higher in both HT groups, and SDI of the HT-1 group was much higher than that of HT-2 group. Compared with the control group, apical rotation (RoA), twist and torsion in the both HT groups decreased significantly. There were no significant differences in these values between the 2 HT groups; Basal rotation (RoB) showed no significantly difference among the 3 groups. GS in the both HT groups decreased significantly compared with the control group, and there were no significant differences in these values between the 2 HT groups. GPI of the both HT groups was significantly lower than that of the control group; however, GPI of HT-2 group was higher than that of HT-1 group. Multivariate stepwise regression analysis identified global left ventricular longitudinal peak systolic strain (GLS), the time length since surgery, left ventricular mass (LVM), and RoA as predictors of LV GPI. GLS was the most influential to GPI.The values of LV rotation, twist and SDI can be used to assess the LV systolic function and dyssynchrony. The GPI value based on 3D-STI may accurately reflect LV performance changes over time after HT. The GPI value has potential applications in clinical practice. GLS, the time length since surgery, LVM and RoA values can be the predictors of LV global performance, and as long as the left ventricular ejection fraction (LVEF) is preserved, the left ventricular global performance of HT recipients remains stable, and tends to improve over time after HT.

The impact of preload on 3-dimensional deformation parameters: principal strain, twist and torsion

BackgroundStrain analysis is feasible using three-dimensional (3D) echocardiography. This approach provides various parameters based on speckle tracking analysis from one full-volume image of the left ventricle; however, evidence for its volume independence is still lacking.MethodsFifty-eight subjects who were examined by transthoracic echocardiography immediately before and after hemodialysis (HD) were enrolled. Real-time full-volume 3D echocardiographic images were acquired and analyzed using dedicated software. Two-dimensional (2D) longitudinal strain (LS) was also measured for comparison with 3D strain values.ResultsLongitudinal (pre-HD: −24.57 ± 2.51, post-HD: −21.42 ± 2.15, P < 0.001); circumferential (pre-HD: −33.35 ± 3.50, post-HD: −30.90 ± 3.22, P < 0.001); and radial strain (pre-HD: 46.47 ± 4.27, post-HD: 42.90 ± 3.61, P < 0.001) values were significantly decreased after HD. The values of 3D principal strain (PS), a unique parameter of 3D images, were affected by acute preload changes (pre-HD: −38.10 ± 3.71, post-HD: −35.33 ± 3.22, P < 0.001). Twist and torsion values were decreased after HD (pre-HD: 17.69 ± 7.80, post-HD: 13.34 ± 6.92, P < 0.001; and pre-HD: 2.04 ± 0.86, post-HD:1.59 ± 0.80, respectively, P < 0.001). The 2D LS values correlated with the 3D LS and PS values.ConclusionVarious parameters representing left ventricular mechanics were easily acquired from 3D echocardiographic images; however, like conventional parameters, they were affected by acute preload changes. Therefore, strain values from 3D echocardiography should be interpreted with caution while considering the preload conditions of the patients.

Echocardiographic reference ranges for normal left ventricular 2D strain: results from the EACVI NORRE study.

To obtain the normal ranges for 2D echocardiographic (2DE) measurements of left ventricular (LV) strain from a large group of healthy volunteers accounting for age and gender. A total of 549 (mean age: 45.6 ± 13.3 years) healthy subjects were enrolled at 22 collaborating institutions of the Normal Reference Ranges for Echocardiography (NORRE) study. 2DE data sets have been analysed with a vendor-independent software package allowing homogeneous measurements irrespective of the echocardiographic equipment used to acquire the data sets. The lowest expected values of LV strains and twist calculated as ± 1.96 standard deviations from the mean were -16.7% in men and -17.8% in women for longitudinal strain, -22.3% and -23.6% for circumferential strain, 20.6% and 21.5% for radial strain, and 2.2 degrees and 1.9 degrees for twist, respectively. In multivariable analysis, longitudinal strain decreased with age whereas the opposite occurred with circumferential and radial strain. Male gender was associated with lower strain for longitudinal, circumferential, and radial strain. Inter-vendor differences were observed for circumferential and radial strain despite the use of vendor-independent software. Importantly, no intervendor differences were noted in longitudinal strain. The NORRE study provides contemporary, applicable 2D echocardiographic reference ranges for LV longitudinal, radial, and circumferential strain. Our data highlight the importance of age- and gender-specific reference values for LV strain.

Consecutive non-natural PZ nucleobase pairs in DNA impact helical structure as seen in 50 μs molecular dynamics simulations.

Little is known about the influence of multiple consecutive ‘non-standard’ (Z, 6-amino-5-nitro-2(1H)-pyridone, and P, 2-amino-imidazo[1,2-a]-1,3,5-triazin-4(8H)-one) nucleobase pairs on the structural parameters of duplex DNA. P:Z nucleobase pairs follow standard rules for Watson–Crick base pairing but have rearranged hydrogen bonding donor and acceptor groups. Using the X-ray crystal structure as a starting point, we have modeled the motions of a DNA duplex built from a self-complementary oligonucleotide (5΄-CTTATPPPZZZATAAG-3΄) in water over a period of 50 μs and calculated DNA local parameters, step parameters, helix parameters, and major/minor groove widths to examine how the presence of multiple, consecutive P:Z nucleobase pairs might impact helical structure. In these simulations, the PZ-containing DNA duplex exhibits a significantly wider major groove and greater average values of stagger, slide, rise, twist and h-rise than observed for a ‘control’ oligonucleotide in which P:Z nucleobase pairs are replaced by G:C. The molecular origins of these structural changes are likely associated with at least two differences between P:Z and G:C. First, the electrostatic properties of P:Z differ from G:C in terms of density distribution and dipole moment. Second, differences are seen in the base stacking of P:Z pairs in dinucleotide steps, arising from energetically favorable stacking of the nitro group in Z with π–electrons of the adjacent base.

Torsional behavior of RC beams strengthened with PBO-FRCM composite – An experimental study

The use of fiber reinforced cementitious matrix (FRCM) composites has been studied for flexural and shear strengthening of reinforced concrete (RC) members, but currently there are no studies on its use for torsional strengthening. This paper presents the results of an experimental study in which solid rectangular RC beams were externally strengthened with PBO-FRCM composite material in different wrapping configurations to investigate the torsional behavior in terms of strength, rotational ductility, and failure mode. Increases in the cracking torque, torsional strength, and corresponding values of twist were achieved by beams strengthened with a 4-sided wrapping configuration relative to the control (unstrengthened) beam. On the other hand, the 3-sided wrapping configuration was found to be largely ineffective in improving the torsional performance due to excessive fiber slippage. The contribution of the strengthening system to the torsional strength was reasonably predicted (±20%) by the strain measured in the composite fibers. Provisions used to estimate the torsional strength of RC beams with fully-wrapped, externally-bonded fiber reinforced polymer (FRP) composites were found to be applicable to beams strengthened with PBO-FRCM composite.

Molecular structure and conformational behavior of 1-methyl-1-phenylsilacyclohexane studied by gas electron diffraction, IR spectroscopy and quantum chemical calculations

Conformational properties and molecular structure of 1-methyl-1-phenylsilacyclohexane 1 were studied by quantum chemical (QC) calculations, combined gas electron diffraction/mass spectrometry (GED/MS) and IR spectroscopy. Molecule 1 may exist in four forms that differ by axial or equatorial positions of the substituents and by relative orientation of the two rings. Two of these conformers were found to dominate in the gas phase: 1-Pheq-orth conformer with the phenyl ring plane bisecting the CSiC endocyclic angle, and 1-Phax-twist with the phenyl ring and the CSiC exocyclic angle oriented nearly perpendicularly to each other. From the GED data, the summarized molar fractions of the conformers were found to be Pheq:Phax = 42(15):58(15)% which corresponds to ΔG = Geq–Gax = 0.19(37) kcal/mol. Experimental and calculated IR spectra provides an evidence of existence of both conformers in the liquid phase. The QC calculations yielded the ΔG = G(Pheq–orth)–G(Phax–twist) values of 0.18–0.36 DFT and 0.82 MP2 kcal/mol.

Left ventricular twist was decreased in isolated left bundle branch block with preserved ejection fraction.

Objective:Left ventricular (LV) rotation and twist play an important role in LV contraction and relaxation. Left bundle branch block (LBBB) deteriorates both diastolic and systolic functions. We evaluated the LV twist in patients with LBBB and preserved ejection fraction (EF) (>50%) to determine twist as a potential marker for subtle myocardial dysfunction.Methods:This observational cross-sectional study included 34 LBBB patients with preserved EF who were free from ischemic and valvular disease (Group 1) and 36 healthy controls (Group 2). All patients underwent 2-D Doppler and 2-D speckle tracking echocardiography. LV apical, basal rotation, and twist were evaluated in both groups and compared accordingly. In addition, subjects were dichotomized considering the median twist value of the study population. Binary logistic regression analysis was performed to determine the independent variables associated with inframedian twist.Results:Baseline clinical characteristics were similar in LBBB patients and controls. Mean apical rotation (2.5°±1.9° vs. 4.4°±2.9°; p=0.002), basal rotation (-2.9°±2.3° vs. -4.1°±2.7°; p=0.05), and twist (5.4°±3° vs. 8.6°±3.3°; p<0.001) were decreased in group 1. Parameters related to intra- and interventricular mechanical dyssynchrony, such as longitudinal left ventricular dyssynchrony index (LVdys) and preejection interval of LV, interventricular mechanical delay (IVMD), and left posterior wall contractions (SPMWD) were significantly higher in the LBBB group. The median twist value of the studied population was 6.65°. Binary logistic regression analysis showed that only presence of LBBB was independently associated with inframedian twist (OR=6.250; 95% CI: 2.215–17.632; p<0.001).ConclusionThe LBBB might have induced the reduction of LV twist by diminishing the LV rotation before inducing a prominent effect on the left ventricular ejection fraction (LVEF). Therefore, twist may be considered as a marker for subtle LV dysfunction in LBBB with substantially normal EF.

Left ventricular rotational mechanics in early infancy: Normal reference ranges and reproducibility of peak values and time to peak values

IntroductionLeft ventricular cardiac twist and torsion values have been described in premature and term neonates, but not in early infancy. Early and late peak untwist rates and time to peak (TTP) values have not been described in infants. Methods53 term infants were enrolled prospectively. The following parameters were obtained by two blinded observers at 1–2months postnatal age: peak twist and torsion (twist indexed to LV length), peak twist rate and torsion rate, TTP twist, early peak untwist rate, TTP early untwist rate, late peak untwist rate, TTP late untwist rate. Reproducibility was assessed using intraclass correlation and Bland Altman analysis. ResultsIntraclass correlation was ≥0.87 for all peak rotational mechanics values. Measures of TTP values had intraclass correlation (ICC) values ≤0.77, with TTP twist rate demonstrating the lowest ICC (0.69). The only measure which demonstrated significant bias was TTP twist rate. Peak twist demonstrated modest correlation (R=0.52, p<0.001) with global circumferential strain, and no correlation with ejection fraction, global longitudinal strain, or left ventricular myocardial performance index. ConclusionsMeasurements of rotational mechanics and timing to peak values have acceptable reproducibility. Peak twist, twist rate, and early untwist rate values in early infancy are similar to those reported in premature neonates, and higher than those reported in older children. Twist indexed to LV length (torsion) is lower in early infancy than in premature neonates, but higher than in term neonates.

Exact special twist method for quantum Monte Carlo simulations

We present a systematic investigation of the special twist method introduced by Rajagopal $\textit{et al.}$ [ Phys. Rev. B 51, 10591 (1995) ] for reducing finite-size effects in correlated calculations of periodic extended systems with Coulomb interactions and Fermi statistics. We propose a procedure for finding special twist values which, at variance with previous applications of this method, reproduce the energy of the mean-field infinite-size limit solution within an adjustable (arbitrarily small) numerical error. This choice of the special twist is shown to be the most accurate single-twist solution for curing one-body finite-size effects in correlated calculations. For these reasons we dubbed our procedure "exact special twist" (EST). EST only needs a fully converged independent-particles or mean-field calculation within the primitive cell and a simple fit to find the special twist along a specific direction in the Brillouin zone. We first assess the performances of EST in a simple correlated model such as the 3D electron gas. Afterwards, we test its efficiency within $\textit{ab initio}$ quantum Monte Carlo simulations of metallic elements of increasing complexity. We show that EST displays an overall good performance in reducing finite-size errors comparable to the widely used twist average technique but at a much lower computational cost, since it involves the evaluation of just one wavefunction. We also demonstrate that the EST method shows similar performances in the calculation of correlation functions, such as the ionic forces for structural relaxation and the pair radial distribution function in liquid hydrogen. Our conclusions point to the usefulness of EST for correlated supercell calculations, our method will be particularly relevant when the physical problem under consideration requires large periodic cells.

Application of micro-computed tomography (micro-CT) to study unevenness of the structure of yarns

A study was conducted on the structure of a single cotton yarn using micro-computer tomography (micro-CT). This article describes two important parameters determining the unevenness of yarn structure, i.e. the migration of staple fibers and packing density of staple fibers in the yarn cross-section. Relationships were found between the variation of staple fiber migration characteristics and the relationship between yarn durability and twist. For the boundary value, the radius and range of migration are the highest, and the variation coefficient of the fiber migration range is the lowest. The number of fibers in the yarn cross-section decreases with twist. Above the boundary twist value, the number of fibers in the yarn cross-section stabilizes at the value corresponding to the number of fibers in the boundary twist.

Left Ventricular Strain and Rotation by 2-D Speckle Tracking Echocardiography Identify Early Alcoholic Cardiomyopathy

This study assessed whether 2-D speckle tracking echocardiography (STE) derived from left ventricular (LV) strain and rotation is capable of detecting LV dysfunction associated with alcoholic cardiomyopathy. Ninety-two male chronic alcoholic patients were grouped by alcohol intake amount and duration: mild (n = 30; >90 mg ethanol daily, 3–5 d per wk for 5–8 y); moderate (n = 30; >90–150 mg ethanol daily, 3–5 d per wk for 9–20 y); and severe (n = 32; >150 mg ethanol daily, 6–7 d per wk for >10 y). Thirty non-drinkers were recruited as healthy controls. Rotation and twist values were lower in the severe group compared with the other groups (p < 0.05). The moderate and severe alcohol groups demonstrated lower longitudinal, circumferential and radial strain values and early to late filling (E/A) ratios compared with the mild group and non-drinkers (all p < 0.05). 2-D STE–derived strain and rotation are reliable echocardiographic markers for detecting left ventricular dysfunction in patients at risk of developing alcoholic cardiomyopathy.

Modeling of abrasion resistance of Persian handmade wool carpets using response surface methodology

The effect of knot density, pile height, number of ply in pile yarn and pile yarn twist on abrasion resistance of Persian handmade wool carpets has been studied. The interaction between the process variables has been analyzed by using response surface methodology based on the Box-Behnken design of experiment. Knot density, pile height, interactions between knot density and pile height; pile height and pile yarn twist; as well as squares of the knot density, pile height and number of ply in pile yarn are significant process variables. The minimum abrasion loss occurs at the combination(s) of medium values of knot density (six knots per inch) and number of ply in pile yarn (three ply) as well as lower values of pile height (ten mm) and pile yarn twist (three and a half twists per inch).

EART HEMODYNAMICS IN EARLY PERIOD OF ACUTE ST ELEVATION ANTERIOR MYOCARDIAL INFARCTION BY 2D SPECKLE TRACKING ECHOCARDIOGRAPHY

Aim. To assess the changes in biomechanics of the heart at early stages post-acute ST-elevation myocardial infarction (MI) by 2D speckle tracking echocardiography. Material and methods. Totally, 35 patients included (mean age — 58,46±10,2 year old) with acute Q-MI admitted within 24 hours from the disease onset. Echocardiography, including 2D speckle tracking regimen was done at the 3rd (T1), 7th (T2) and 14th (T3) day post-MI (Vivid E9 device). Patients were selected to two groups: with an adverse remodeling of the left ventricle (LVR+) by 14th day and without (LVR-). Results. Urgent reperfusion was done in all patients, and in 72% within 6 hours. There was no significant dynamics of the standard echocardiography parameters — enddiastolic volume (EDV) and end-systolic volume (ESV), ejection fraction (EF), index of local contractility disorder (ILCD) of theLV.There was improved deformity — 2D global longitudinal strain (GLS) by T2 (p=0,048). Apical and basal rotation — without dynamics during all follow-up period. However, number of patients with normal and decreased value of basal rotation and its systolic velocity, as with normal and increased value of apical rotation and its systolic velocity, increased by T3 (p&lt;0,05). There was increase of systolic twist velocity by T3. In LVR+ group there was improvement of ILCD and 2D GLS by T3. Systolic velocity of apical rotation and twist increased by T3, however all velocity parameters were significantly lower than in LVR-. Clinically the groups differed by the time of reperfusion: 5,48±3,58 vs 3,89±2,25 hours (р&gt;&lt;0,05). Conclusion. Changes in biomechanics of the heart by 2D speckle tracking echocardiography in patients with the use of modern and on-time pharmacoinvasive strategy at early post-infarction period represented the restoring of cardiac function, while standard parameters (ESV, EDV, EF LV) did not show dynamics. Improvement of 2D GLS was found even at T2 point. Among the values reflecting rotational characteristics of LV, the systolic velocity of apical rotation by T3. There was no dynamics in basal and apical rotation. The number of patients increased, with normal and increased apical rotation, as with decreased and normal basal rotation &gt;&lt; 0,05). Conclusion. Changes in biomechanics of the heart by 2D speckle tracking echocardiography in patients with the use of modern and on-time pharmacoinvasive strategy at early post-infarction period represented the restoring of cardiac function, while standard parameters (ESV, EDV, EF LV) did not show dynamics. Improvement of 2D GLS was found even at T2 point. Among the values reflecting rotational characteristics ofLV, the systolic velocity of apical rotation by T3. There was no dynamics in basal and apical rotation. The number of patients increased, with normal and increased apical rotation, as with decreased and normal basal rotation by T3. In LVR+ group myocardial reperfusion was achieved significantly later, there was improvement of 2D GLS and ILCD of LV by T3, as well as velocity values of apical rotation and twist.

Left Ventricular Myocardial Deformation Parameters Are Affected by Coronary Slow Flow Phenomenon: A Study of Speckle Tracking Echocardiography.

The coronary slow flow phenomenon (CSFP) is defined as a delayed distal vessel contrast opacification in the absence of obstructive epicardial coronary artery disease during coronary angiography. There is conflicting data in medical literature regarding the effects of CSFP on the left ventricular functions assessed by conventional echocardiography or tissue Doppler imaging. Therefore, we aimed to evaluate whether there is any abnormality in the myocardial deformation parameters (strain, strain rate (SR), rotation, twist) of the left ventricle obtained by speckle tracking echocardiography (STE) in patients with CSFP. Twenty patients with CSFP were included prospectively in the study. Another 20 patients with similar demographics and cardiovascular risk factors as well as normal coronary angiography were used as the control group. Two-dimensional echocardiographic images of the left ventricle from the apical long-axis, two-chamber, four-chamber, and parasternal short-axis views were used for STE analysis. The analysis of left ventricular circumferential deformation parameters showed that the averaged peak systolic strain, systolic SR, and early diastolic SR values were significantly lower in patients with CSFP (P = 0.009, P = 0.02, and P = 0.02, respectively). Among the left ventricular rotation and twist values, apical rotation was significantly lower in patients with CSFP (P = 0.02). Further, the mean thrombolysis in myocardial infarction frame count value was found to be negatively correlated with the averaged peak circumferential early diastolic SR (r = -0.35, P = 0.03). It was positively correlated with the averaged peak circumferential systolic strain (r = 0.47, P = 0.003) and circumferential systolic SR (r = 0.46, P = 0.005). Coronary slow flow phenomenon leads to significant alterations in the myocardial deformation parameters of the left ventricle as assessed by STE. Specifically, circumferential deformation parameters are affected in CSFP patients.