Maximum Velocity Difference Research Articles

Features of myometrium remodeling after surgical inteventions on the uterus

Introduction. Recently, the attention of researchers has again attracted the problem of pregnancy in the presence of scar on the uterus.The aim of the study is to evaluate the processes of myometrium remodeling in women with uterine scar using non-invasive ultrasonic monitoring. It is shown that the frequency of relative failure of yellowing in the uterus does not exceed 2.7% of the total number of women examined. The ratio of the thickness of the residual in the plane of the yellow and normal endometrium indicates complete remodeling and is in women after KP, this index was 0.96 ± 0.08, and after KME - 0.94 ± 0.06 (p> 0.05). The difference in maximum systolic velocity of arterial blood flow in patients after CR (38.8 ±1.2 cm/ s) and after CME (34.2 ±1.4 cm/ sec, p <0.05) can be explained by differences in localization cuts during these surgical interventions . The expediency of using both linear and dopplerometric methods of ultrasound examination in evaluating the ability of rumen on the uterus and myometrium remodeling processes is discussed.

Variability of Twin Boundary Velocities in 10M Ni–Mn–Ga Measured Under $$\upmu{\text{s}}$$-Scale Force Pulses

Twin boundary motion is the basic mechanism responsible for fast actuation of magnetic shape memory (MSM) alloys. Previous studies implied on a wide diversity of twin boundary velocities measured under similar conditions. Here, a data set of more than 400 velocity values is measured under conditions that are relevant for MSM applications and represents the dynamic behavior of 73 twin boundaries. Velocities are measured using an electro-mechanical setup that applies a controllable $$\upmu{\text{s}}$$ -scale force pulse and combines force measurements with high-speed imaging. The latter allows extracting velocities of individual twin boundaries, which are then correlated to the macroscopic stress in the sample. The appearance of type I twins is more prevalent than type II, resulting a much larger data set for type I twins. Statistical analysis of velocity points of type I twins reveals an increasing trend of the velocity with the macroscopic stress, as well as useful information on the probability distribution of velocity data. Velocities of type II twins exhibit large variability over a relatively narrow stress range. This can reason the large differences in maximal velocities reported previously for this twin type. The obtained statistical data can improve the design and modeling of MSM actuators.

Slug flow identification using ultrasound Doppler velocimetry

An identification method of slug flow using velocity information was developed in this study. Quantitative analysis of two-phase (gas–liquid) flow in horizontal pipes is essential to ensure the stability of, or to accurately estimate the thermal performance of, various engineering applications. The spatial and temporal distribution of liquid velocity was measured using the ultrasound Doppler velocimetry method under various superficial velocity conditions. From the results, we proposed a novel identification method of the slug flow based on two parameters, the maximum velocity and maximum velocity difference ratio. In addition, the ratio of liquid velocities between the slug body and the bubble area is a reliable parameter for separating the slug flow from the plug flow. Finally, we investigated the changes in moving velocity, slug frequency, and slug length along the pipeline under a wide range of superficial velocities. The results show that the liquid and gas superficial velocity have the opposite effect on the slug frequency, except in the downstream region. It was found that the slug body length increased continually along the pipe and the average slug body length in the downstream region is invariant regardless of the gas superficial velocity.

Variation of the maximum velocity along the umbilical vein supports the Reynolds pulsometer model

ObjectiveTo challenge, with a modern sonographic approach and a numerical model, the Reynolds’s concept which suggests that the vascular structure of the umbilical cord could act as a pulsometer facilitating the venous return to the foetus. MethodForty-five patients between 20 and 28 weeks of gestation were included in the study. The blood maximum velocity in the umbilical vein, measured at both foetal and placental ends, was assessed. Several sonographic parameters of the cord, including the diameter of the umbilical vein at both extremities, cord cross-sectional area and Wharton’s jelly section surface were measured. We compare our data with those of a numerical model. ResultsA difference in maximum velocity between the two extremities of the umbilical vein (ΔUV Vmax) was noted. The maximum velocity was significantly higher at the foetal umbilical end (14.12 +/-3.18 cm/s) than at the placental end (11.93 +/-2.55 cm/s; p < 0.0001). The mean difference is 2.2 +/- 2.3 cm/s. No difference in the umbilical vein diameter was measured at both cord ends (umbilical 4.85 +/-0.9 mm, placental 4.86 +/-0.87 mm, p < 0.0001). There is no significant relationship between ΔUV Vmax and the cord cross-sectional area or Wharton’s jelly index. ConclusionModifications of the spatial velocity profile together with the pulsometer model could explain the maximum velocity changes that is measured in the umbilical vein along the cord. This numerical model consolidates the sonographic observations.

Validation of an 8-minute Self-Paced Graded Exercise Testing Protocol to Elicit Maximal Responses

Recent examinations have turned to the development and validation of a 10-min self-paced graded exercise testing protocol. The 10-min duration was chosen because it represents the mean value of the recommended 8-12min ideal protocol duration; however, literature exists suggesting that an 8min duration may be more appropriate to elicit maximal exercise responses. Furthermore, a gender effect may exist to explain the finding. PURPOSE: We sought to examine maximal exercise responses during an 8-min self-paced (8SPV), 10-min self-paced (10SPV) and standardized graded exercise testing (GXT) treadmill protocols. METHODS: Sixteen recreationally active males (n=8) and females (n=8) completed three separate tests in a randomized order: a) 8SPV consisting of eight 1-min stages of increasing speed clamped by the Borg RPE6-20 scale, b) 10SPV consisting of five 2-min stages clamped of increasing speed clamped by the Borg RPE6-20 scale, c) traditional Bruce protocol as the GXT. 8SPV and 10SPV maintained a 3% grade. A two-way (gender x protocol) ANOVA with repeated measures was employed to examine differences in maximal responses between protocols. Paired samples t-tests were used to examine the difference in maximal velocity between 8SPV and 10SPV. RESULTS: No gender effects were revealed. Maximal values for 8SPV, 10SPV and GXT were similar (p > 0.05) for oxygen consumption (48.0±5.6; 51.8±10.5; 51.4±7.5 mL•kg-1•min-1), heart rate (193±11; 195±9; 194±13 beats•min-1), respiratory exchange ratio (1.11±0.07; 1.12±0.06; 1.13±0.05), ventilation (103.2±22.4; 113.0±30.3; 112.3±33.0 L•min-1), respectively. Maximal velocity for 8SPV and 10SPV were also similar (15.1±3.1 vs. 14.6±2.7 km•hr-1, p > 0.05). CONCLUSION: Given no differences between protocols, 8SPV may serve as a valid and time efficient option to elicit maximal responses during self-paced exercise in recreationally trained college-aged men and women.

Color Doppler imaging in thyroid eye disease and its correlation to disease activity

ABSTRACTPurpose: To evaluate alterations in orbital color Doppler imaging (CDI) parameters and their correlation to disease activity and severity in patients with thyroid eye disease (TED).Methods: Seventy-six orbits of 45 TED patients and 40 orbits of 40 normal controls were enrolled in this cross-sectional study. According to clinical activity score (CAS), patients were categorized to active (CAS ≥ 3) or inactive disease (CAS < 3). Patients were also classified as having mild, moderate or severe disease. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) in ophthalmic artery and central retinal artery, and maximum and minimum velocity in superior ophthalmic vein and central retinal vein were determined in all subjects.Results: There was a significant difference in maximum velocity of superior ophthalmic vein and EDV and RI of ophthalmic artery between patients with TED and normal subjects. Superior ophthalmic vein maximum and minimum velocity and ophthalmic artery RI were significantly higher in patients with active disease than inactive cases. Disease severity did not affect the blood flow parameters independently. A cutoff point of 3.99 cm/s in superior ophthalmic vein maximum velocity yielded a sensitivity of 91.2% and specificity of 81.2% in detecting active disease.Conclusion: Retrobulbar blood flow is altered in TED and is related to disease activity. Superior ophthalmic vein maximum velocity could be helpful in differentiation of active and inactive cases.

Streak formation in flow over biomimetic fish scale arrays.

The surface topology of the scale pattern from the European sea bass (Dicentrarchus labrax) was measured using a digital microscope and geometrically reconstructed using computer assisted design modelling. Numerical flow simulations and experiments with a physical model of the surface pattern in a flow channel mimic the flow over the fish surface with a laminar boundary layer. The scale array produces regular rows of alternating, streamwise low-speed and high-speed streaks inside the boundary layer close to the surface, with maximum velocity difference of approximately 9%. Low velocity streaks are formed in the central region of the scales whereas the high velocity streaks originated in the overlapping region between the scales. Thus, those flow patterns are linked to the arrangement and the size of the overlapping scales within the array. Because of the velocity streaks, total drag reduction is observed when the scale height is small relative to the boundary layer thickness, i.e. less than 10%. Flow simulations were compared with surface oil-flow visualisations on the physical model of the biomimetic surface placed in a flow channel. The results show an excellent agreement in the size and arrangement of the streaky structures. The existence of streaks is also shown on sea bass and common carp (Cyprinus carpio) by surface flow visualisation. From comparisons with recent literature on micro-roughness effects on laminar boundary layer flows, it is hypothesised that the fish scales could delay transition, which would further reduce the drag.

Seismological Evidence for Laterally Heterogeneous Lowermost Outer Core of the Earth

AbstractThe Earth's outer core is believed to be laterally homogeneous because of its low viscosity. However, a hemispherical difference in the inner core likely exists due to its uneven growth, which may be accompanied by localized light‐element releases to the outer core. A few seismological studies proposed heterogeneous lowermost outer core (called F layer) but using methods that are not very sensitive to F layer structures. In a previous study we developed a new method sensitive to the F layer structure and insensitive to others. The method analyzes differences in P wave traveltimes reflected on the inner core boundary and those that turn above the boundary as well as dispersion in waves bottoming or diffracting in the F layer, and was applied to obtain an F layer model of P wave velocity for the northeastern Pacific Ocean. In this paper, we examine the F layer structure beneath Australia using the same method. The observed dispersion requires a lower‐velocity gradient beneath Australia than beneath the northeastern Pacific, whereas the observed traveltime differences require higher average velocities beneath Australia. The results obtained for the two regions indicate that the F layer is laterally heterogeneous and that the layer beneath Australia has a higher velocity and velocity gradient in its upper part and a much smaller gradient in its lower part than beneath northeastern Pacific. The maximum velocity difference between the two regions is 0.04 km/s, which corresponds to 0.8 wt% excess oxygen according to ab initio calculations of elastic properties. These results suggest regional light‐element concentration beneath Australia.

Seven-Day Intensity and Intensity Spread Predictions in Bifurcation Situations with Guidance-On-Guidance for Western North Pacific Tropical Cyclones

An objective technique to detect and predict intensity bifurcation situations in a five-day Weighted Analog Intensity forecast technique for the western North Pacific (WAIP) has been extended to seven days. A hierarchical cluster analysis is applied to the N analog intensities to separate them into two clusters, which are considered to represent a substantial intensity bifurcation if a threshold maximum velocity difference of 15 kt is satisfied. Two important modifications have been made to develop the bifurcation version for seven-day WAIP forecasts. First, the number of track analogs has been increased from 10 analogs to 16 analogs, which results in larger sample sizes and better performance. Second, separate intensity bias corrections are calculated for the two cluster WAIP forecasts rather than using the same 16-analog intensity bias correction. If an always perfect selection of the correct cluster WAIP forecast of each bifurcation situation is made, a substantial improvement in the intensity mean absolute errors is achieved relative to the original WAIP forecasts based on all 16 of the best analogs. These perfect-cluster selection WAIP forecasts have smaller bias errors and are more highly correlated with the verifying intensities at all forecast intervals through 168 h. Furthermore, the Probability of Detection is improved for the perfect-cluster selection and more realistic intensity spreads are specified. A simple guidance-on-guidance technique is demonstrated to assist the forecasters in selecting the correct WAIP cluster forecast in bifurcation situations.

Application and analysis of spread die and flat container in the extrusion of a large-size, hollow, and flat-wide aluminum alloy profile

The structure of the extrusion die has great influence on material flow balance and product quality for large-size aluminum alloy profiles, especially the pre-allocated structure, such as spread die and flat container. In this work, regarding the practical problems existing in practical production of a large-size, hollow, and flat-wide aluminum alloy profile used in the high-speed train, the porthole extrusion process with cylinder container and spread die is firstly simulated using HyperXtrude and verified experimentally. The spread die is then optimized by combining the design of experiments with response surface method. With the optimized spread die, the maximum velocity difference in the cross section of the profile reduces from 8.63 to 3.07 mm/s, and the corresponding SDV reduces from 1.56 to 0.69 mm/s. Finally, the different structures of containers are designed; the effects of cylinder container and flat containers with different transition form on material flow, billet skin, and die stress in numerical simulation process are comparatively analyzed; and the design rules of extrusion dies are summarized for large-size, hollow, and flat-wide aluminum alloy profiles. By comparison, the maximum velocity difference decreases from 14.41 to 3 mm/s, and the maximum stress on the extrusion dies decreases from 999 to 670 MPa, and the dead zone also greatly decreases in flat container extrusion.

ACTA1-Related Nemaline Myopathy Mutations Engender a Range of Structural and Functional Phenotypes in Drosophila Indirect Flight Muscles

Nemaline myopathy is a congenital disorder characterized by muscle weakness. Dominant-negative disease-causing mutations have been identified in various genes that encode sarcomeric thin filament proteins. of these, mutations in skeletal muscle α-actin (ACTA1) account for ∼25% of all reported cases. To investigate the myopathic phenotypes from the level of whole muscle down through the level of single molecules, we generated multiple transgenic Drosophila fly lines expressing three different mutations - V37L, D288G and F352S - in Act88F, the indirect flight muscle (IFM) actin gene. A gradation in flight behavior was observed (V37L>D288G>F352S), which correlated with the observed differences in muscle fiber morphology. While most of these mutations depress muscle function in patients, the F352S lesion elevates myosin cross-bridge strain and steady-state isometric force production and, thereby, apparently increases contractile function. Confocal and electron microscopy revealed breaks in mutant F352S IFM fibers and extensive myofibrillar and myofilamentous disarray. Z-lines showed streaming and formed “zebra bodies”. The microscopic alterations are consistent with excessive acto-myosin interactions, unevenly distributed force, and destructive hypercontraction. Interestingly, in vitro sliding velocities of purified IFM F-actin from wild-type (3.17±0.12 μm/s) vs. F352S mutant heterozygous (2.88±0.09 μm/s, mean±SEM) flies did not significantly differ. Similarly, no differences in maximum calcium-activated velocity (3.88±0.11 vs. 3.77±0.10 μm/s) or in cooperativity (nH = 2.13±0.27 vs. 2.62±0.46) were observed for F-actin in the presence of vertebrate tropomyosin and troponin. However, relative to control, F352S heterozygous filaments showed a significant (p<0.01) increase in calcium sensitivity (pCa50 = 5.99±0.03 vs. 6.11±0.03), consistent with a mutation-induced gain in molecular function. Going forward, our novel Drosophila models will be used to screen for in vivo modifiers of mutant muscle performance. Supported by NIH R01HL124091 to AC.

Upper limb kinematics of adults with cerebral palsy on bilateral functional tasks.

Adults with cerebral palsy (CP) often show upper limb impairments which impact their ability to execute activities of daily living (ADLs). Three adults with CP and five healthy adults performed three types of bilateral and unilateral ADLs: drink, pour, and pick and place tasks. An affordable bilateral assessment system (BiAS) was used to measure wrist kinematic trajectories. Four metrics, total completion time, maximum velocity, smoothness, and phase difference, were used to evaluate each functional task. Overall, adults with CP took a longer time than the healthy subjects to complete all unilateral functional tasks with their non-dominant hand. Moreover, while the healthy controls had similar mean velocities in the dominant and non-dominant hands during the bilateral tasks, adults with CP typically exhibited slower mean velocities in the dominant hand during the bilateral tasks than during the unilateral dominant tasks. Similar to existing literature, we found that adults with CP compensated by slowing the dominant arm to match the non-dominant arm in order to complete the tasks, showing the importance of utilizing bilateral training in upper limb rehabilitation treatments.

Microgeographic variation in locomotor traits among lizards in a human-built environment.

Microgeographic variation in fitness-relevant traits may be more common than previously appreciated. The fitness of many vertebrates is directly related to their locomotor capacity, a whole-organism trait integrating behavior, morphology, and physiology. Because locomotion is inextricably related to context, I hypothesized that it might vary with habitat structure in a wide-ranging lizard, Podarcis erhardii, found in the Greek Cyclade Islands. I compared lizard populations living on human-built rock walls, a novel habitat with complex vertical structure, with nearby lizard populations that are naive to human-built infrastructure and live in flat, loose-substrate habitat. I tested for differences in morphology, behavior, and performance. Lizards from built sites were larger and had significantly (and relatively) longer forelimbs and hindlimbs. The differences in hindlimb morphology were especially pronounced for distal components—the foot and longest toe. These morphologies facilitated a significant behavioral shift in jumping propensity across a rocky experimental substrate. I found no difference in maximum velocity between these populations; however, females originating from wall sites potentially accelerated faster over the rocky experimental substrate. The variation between these closely neighboring populations suggests that the lizards inhabiting walls have experienced a suite of trait changes enabling them to take advantage of the novel habitat structure created by humans.

The Actin F352S Nemaline Myopathy Mutation Disrupts Indirect Flight Muscle Structure and Function in Drosophila

Nemaline myopathy is a congenital human muscle disorder characterized by masticatory, limb and respiratory weakness. Dominant negative disease-causing mutations have been identified in ten genes that notably encode sarcomeric thin filament proteins including α actin (ACTA1). While most of these mutations cause a loss of muscle function, the F352S actin mutation elevates myosin cross-bridge strain and steady-state isometric force production and, thereby, apparently increases contractile function in humans. To investigate the F352S-induced myopathic cascade from the level of single molecules through the level of whole muscle we generated transgenic Drosophila that express the mutation in Act88F, the indirect flight muscle (IFM) actin gene. Mutant heterozygotes were flightless. Fluorescent and electron microscopy revealed breaks in mutant IFM fibers and extensive myofibrillar disarray. For example, the highly ordered double hexagonal thin/thick filament lattice, at the periphery of myofibrils, was distorted with myofilaments occasionally losing longitudinal orientation. Z-lines showed streaming and formed “zebra bodies”. The microscopic alterations are consistent with inappropriate acto-myosin interaction, unevenly distributed force, and destructive hypercontraction. Interestingly, in vitro sliding velocities of purified IFM F-actin from wild-type (3.17±0.12 μm/s) vs. F352S mutant heterozygous (2.88±0.09 μm/s, mean±SEM) flies did not significantly differ. Similarly, no differences in maximum calcium-activated velocity (3.88±0.11 vs. 3.77±0.10 μm/s) or in cooperativity (nH = 2.13±0.27 vs. 2.62±0.46) were observed for F-actin in the presence of tropomyosin and troponin. However, F352S heterozygous filaments showed a significant (p < 0.01) increase in calcium sensitivity relative to control (pCa50 = 6.11 +/- 0.03 vs. 5.99 +/- 0.03), consistent with mutation-induced gain in molecular function. Going forward, our novel Drosophila model will be used to screen for in vivo modifiers of mutant muscle performance.Supported by NIH 2PO1 AR052354 (P.D. Allen PI; CFA Core D).

Morphology and motion: hindlimb proportions and swing phase kinematics in terrestrially locomoting charadriiform birds.

Differing limb proportions in terms of length and mass, as well as differences in mass being concentrated proximally or distally, influence the limb's moment of inertia (MOI), which represents its resistance to being swung. Limb morphology - including limb segment proportions - thus probably has direct relevance for the metabolic cost of swinging the limb during locomotion. However, it remains largely unexplored how differences in limb proportions influence limb kinematics during swing phase. To test whether differences in limb proportions are associated with differences in swing phase kinematics, we collected hindlimb kinematic data from three species of charadriiform birds differing widely in their hindlimb proportions: lapwings, oystercatchers and avocets. Using these three species, we tested for differences in maximum joint flexion, maximum joint extension and range of motion (RoM), in addition to differences in maximum segment angular velocity and excursion. We found that the taxa with greater limb MOI - oystercatchers and avocets - flex their limbs more than lapwings. However, we found no consistent differences in joint extension and RoM among species. Likewise, we found no consistent differences in limb segment angular velocity and excursion, indicating that differences in limb inertia in these three avian species do not necessarily underlie the rate or extent of limb segment movements. The observed increased limb flexion among these taxa with distally heavy limbs resulted in reduced MOI of the limb when compared with a neutral pose. A trade-off between exerting force to actively flex the limb and potential savings by a reduction of MOI is skewed towards reducing the limb's MOI as a result of MOI being in part a function of the radius of gyration squared. Increased limb flexion is a likely means to lower the cost of swinging the limbs.

Quantifying the effects of load carriage and fatigue under load on sacral kinematics during countermovement vertical jump with IMU-based method

We present a method for quantifying sacral kinematics during countermovement jumping (CMJ) using an inertial measurement unit (IMU). The IMU-derived sacral kinematic trajectories reproduced motion capture acceleration, velocity, and displacement to within mean (standard deviation) differences of 0.024 (0.088) m/s2, 0.023 (0.026) m/s, and 0.003 (0.032) m, respectively, across 252 jumps performed by 14 subjects. The method also quantified differences in maximum sacral displacement to within 1 % and differences in maximum propulsive velocity to within 0.7 % of motion capture estimates. This builds upon existing IMU-based methods for quantifying jump performance, which do not provide sacral kinematic trajectories. The utility of this method is demonstrated by its ability to discriminate jump performance metrics across a diverse subject population. In particular, we found that 21 participants adopted multiple strategies to maximize jump height in unloaded and loaded fresh conditions, but converged to a common strategy when jumping fatigued and under load. Changes in kinematic parameters were evident across conditions, and several changes were significantly associated with changes in jump performance (i.e., height). These parameters include changes in the depth of the countermovement, duration of the propulsive phase and maximum propulsive velocity. Collectively, these results point toward the future use of this method in naturalistic environments and for multiple objectives including biomechanical performance assessment and tracking, fatigue assessment, and jump training.

Effect of Offshore Wind farm Design on the Vertical Motion of the Ocean

In this study the vertical motion of the ocean is studied numerically. A wake model that includes details of the wind farm design, such as the location of the turbines, diameter of rotors and hub height, is used to calculate the change in surface wind speed resulting from potential wind farms in the Havsul area. Using the calculated wind velocities to force a three dimensional ocean model (Regional Ocean Modeling System), the ocean response to two different wind farm designs is estimated. It is found that the wind farm design has a significant effect on the upwelling and downwelling near the wind farm, as the difference in maximum upwelling velocity after 1 day of simulation exceeds 30 m/day. The pronounced changes in vertical velocities are attributed to changes in the horizontal flow over varying topography due to wind stress modifications by the wind farms.

Analysis of Empirical Constant of Eddy Viscosity by Zero- and One-Equation Turbulence Model in Wake Simulation

In this paper, the wakes behind a square cylinder were simulated using two kinds of different turbulence models for the eddy viscosity concept such as the zero- and the one-equation model in which the former is the mixing length model and the latter is the k-equation model. For comparison between numerical and analytical solutions, we employed three skill assessments: the correlation coefficient(r) for the similarity of the wake shape, the error of maximum velocity difference(EMVD) for the accuracy of wake velocity and the ratio of drag coefficient(RDC) for the pressure distribution around the structure. On the basis of the numerical results, the feasibility of each model for wake simulation was discussed and a suitable value for the empirical constant was suggested in these turbulence models. The zero-equation model, known as the simplest turbulence model, overestimated the EMVD and its absolute mean error(AME) for r , EMVD and RDC was ranging from 20.3 % to 56.3 % for all test. But the AME by the one-equation model was ranging from 3.4 % to 19.9 %. The predicted values of the one-equation model substantially agreed with the analytical solutions at the empirical mixing length scale L+0.6b 1/2 with the AME of 3.4 %. Therefore it was concluded that the one-equation model was suitable for the wake simulation behind a square cylinder when the empirical constant for eddy viscosity would be properly chosen.

Vertical mixing layer development

A new generation of current and wave testing tanks is required to simulate more realistic sea conditions at larger scales. One means of producing a current is by using groups of impellers arranged around the perimeter of a circular tank. Each propeller produces a single flow velocity which may be different to its neighbours. These differences can lead to a stepped or curved plan view velocity profile in the test section of the tank where a plug profile is required. It is important to understand what the maximum allowable velocity difference between each impeller can be before the required plug profile in the test section is compromised.The situation where two individual fluid streams combine, leading to a turbulent mixing layer, is found in many applications and is therefore of great interest in wider fluid dynamics.In the experimental work presented a setup is described which combines two water flows at different velocities to create a vertical shear. The evolution of the combined flow is studied using Particle Image Velocimetry (PIV). When analysed, these results lead to an understanding of various aspects of mixing layer flow recovery and how the bulk flow rates and velocity ratio affected them.

Tissue Doppler imaging for diagnosis of coronary artery disease: a systematic review and meta-analysis

Global and regional left ventricular (LV) systolic dysfunction is a marker of coronary artery disease (CAD), which is conventionally assessed using two-dimensional echocardiography. Tissue Doppler imaging (TDI) has emerged as an adjunct tool in the diagnosis of regional wall motion abnormalities from CAD. We performed a systematic review and meta-analysis to assess the efficacy of TDI indices in the diagnosis of CAD. We searched MEDLINE and the Cochrane Library for controlled studies comparing TDI measurements in those with and without CAD as confirmed by coronary angiography. Meta-analyses of mean differences in TDI velocities between these populations were performed. Screening of titles and abstracts followed by full-text screening identified 8 studies. At rest, TDI was associated with a significant decrease in the pooled maximum systolic velocity among CAD patients compared to those without CAD [mean difference (MD): -0.66; 95% confidence interval (CI): -0.98 to −0.34]. There were no significant differences in maximum early and late diastolic velocities. Post-stress, TDI was associated with a significant decrease in maximum early diastolic velocity (MD: -1.91; 95% CI: -2.74 to −1.09) and maximum late diastolic velocity (MD: -1.57; 95% CI: -2.95 to −0.18) among CAD patients compared to those without CAD. There was no significant difference in maximum systolic velocity post-stress. Our results suggest that TDI may have a role in the evaluation of CAD. Future studies should evaluate the incremental value of TDI velocities over LV ejection fraction and two dimensional wall motion analysis in the detection of CAD and assessment of its severity. (Word Count: 249)