A Closer Look at Precision Hard Turning of AISI4340: Multi-Objective Optimization for Simultaneous Low Surface Roughness and High Productivity.

This article reports an extended investigation into the precision hard turning of AISI 4340 alloy steel when machined by two different types of inserts: wiper nose and conventional round nose. It provides a closer look at previously published work and aims at determining the optimal process parameters for simultaneously minimizing surface roughness and maximizing productivity. In the mathematical models developed by the authors, surface roughness at different cutting speeds, depths of cut and feed rates is treated as the objective function. Three robust multi-objective techniques, (1) multi-objective genetic algorithm (MOGA), (2) multi-objective Pareto search algorithm (MOPSA) and (3) multi-objective emperor penguin colony algorithm (MOEPCA), were used to determine the optimal turning parameters when either the wiper or the conventional insert is used, and the results were experimentally validated. To investigate the practicality of the optimization algorithms, two turning scenarios were used. These were the machining of the combustion chamber of a gun barrel, first with an average roughness (Ra) of 0.4 µm and then with 0.8 µm, under conditions of high productivity. In terms of the simultaneous achievement of both high surface quality and productivity in precision hard turning of AISI 4340 alloy steel, this work illustrates that MOPSA provides the best optimal solution for the wiper insert case, and MOEPCA results are the best for the conventional insert. Furthermore, the results extracted from Pareto front plots show that the wiper insert is capable of successfully meeting both the requirements of Ra values of 0.4 µm and 0.8 µm and high productivity. However, the conventional insert could not meet the 0.4 µm Ra requirement; the recorded global minimum was Ra = 0.454 µm, which reveals the superiority of the wiper compared to the conventional insert.

Cardiac function and cognition in older community-dwelling cardiac patients.

BACKGROUND: Cognitive deficits have been reported in older cardiac patients. An underlying mechanism for these findings may be reduced cardiac function. The relationship between cardiac function as represented by different echocardiographic measures and different cognitive function domains in older cardiac patients remains unknown. METHODS: An older (≥70 years) heterogeneous group of 117 community-dwelling cardiac patients under medical supervision by a cardiologist underwent thorough echocardiographic assessment including left ventricular ejection fraction, cardiac index, left atrial volume index, left ventricular mass index, left ventricular diastolic function, and valvular calcification. During a home visit, a neuropsychological assessment was performed within 7.1 ± 3.8 months after echocardiographic assessment; the neuropsychological assessment included three subtests of a word-learning test (encoding, recall, recognition) to examine one memory function domain and three executive function tests, including digit span backwards, Trail Making Test B minus A, and the Stroop colour-word test. RESULTS: Regression analyses showed no significant linear or quadratic associations between any of the echocardiographic functions and the cognitive function measures. CONCLUSIONS: None of the echocardiographic measures as representative of cardiac function was correlated with memory or executive function in this group of community-dwelling older cardiac patients. These findings contrast with those of previous studies.

The role of ADAMTS13 in acute myocardial infarction: cause or consequence?

AIMS: ADAMTS13, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13, is a metalloprotease that cleaves von Willebrand factor (VWF). There is considerable evidence that VWF levels increase and ADAMTS13 levels decrease in ST-elevation myocardial infarction (STEMI) patients. It is unclear whether this contributes to no reflow, infarct size, and intramyocardial haemorrhage (IMH). We aimed to determine the role of ADAMTS13 in STEMI patients and to investigate the benefits of recombinant ADAMTS13 (rADAMTS13) in a porcine model of myocardial ischaemia-reperfusion. METHODS AND RESULTS: In 49 consecutive percutaneous coronary intervention (PCI)-treated STEMI patients, blood samples were collected directly after through 7 days following PCI. Cardiac magnetic resonance was performed 4-6 days after PCI to determine infarct size and IMH. In 23 Yorkshire swine, the circumflex coronary artery was occluded for 75 min. rADAMTS13 or vehicle was administered intracoronary following reperfusion. Myocardial injury and infarct characteristics were assessed using cardiac enzymes, ECG, and histopathology. In patients with IMH, VWF activity and VWF antigen were significantly elevated directly after PCI and for all subsequent measurements, and ADAMTS13 activity significantly decreased at 4 and 7 days following PCI, in comparison with patients without IMH. VWF activity and ADAMTS13 activity were not related to infarct size. In rADAMTS13-treated animals, no differences in infarct size, IMH, or formation of microthrombi were witnessed compared with controls. CONCLUSIONS: No correlation was found between VWF/ADAMTS13 and infarct size in patients. However, patients suffering from IMH had significantly higher VWF activity and lower ADAMTS13 activity. Intracoronary administration of rADAMTS13 did not decrease infarct size or IMH in a porcine model of myocardial ischaemia-reperfusion. These data dispute the imbalance in ADAMTS13 and VWF as the cause of no reflow.

Three-dimensional speckle tracking echocardiography for the preclinical diagnosis of hypertrophic cardiomyopathy.

The aim is to detect early changes in myocardial mechanics in hypertrophic cardiomyopathy (HCM) mutation carriers, three-dimensional speckle tracking echocardiography (3DSTE) was used for screening of family members in the HCM population. Eighty subjects were divided as: HCM mutation carriers (n = 23), manifest HCM patients (n = 28), and normal controls (n = 29). They prospectively underwent 3DSTE for left atrial (LA) and left ventricle (LV) strain analysis. HCM mutation carriers showed significantly higher LA minimum volume (ml/m(2)) (17 ± 6 vs. 14 ± 4, respectively, P = 0.03) and a significantly lower peak atrial longitudinal strain (PALS) (%), (27 ± 5 vs. 31 ± 7, respectively, P = 0.02) when compared to controls. However, no differences were found in global or regional LV systolic myocardial deformation between both groups. Manifest HCM patients, compared to carriers showed significantly higher LA minimum (27 ± 10 vs. 17 ± 6, respectively, P < 0.001) and maximum volume (42 ± 14 vs. 32 ± 8, respectively, P = 0.007) as well as lower LA ejection fraction (%) (35 ± 8 vs. 47 ± 9, respectively, P < 0.001) and PALS (17 ± 5 vs. 27 ± 5, respectively, P < 0.001). Comparing LV strain, HCM patients showed reduced global longitudinal (-11 ± 4 vs. -16 ± 3, respectively, P < 0.001) and area strain (-35 ± 6 vs. -40 ± 5, respectively, P = 0.005). HCM mutation carriers may be distinguished from healthy subjects using 3DSTE through detection of LA dysfunction that may indicate LV diastolic dysfunction. Further research in a larger study population with gene-specific analysis is warranted for potential clinical usefulness of 3DSTE in family screening for HCM.

Comparison of three-dimensional echocardiographic software packages for assessment of left ventricular mechanical dyssynchrony and prediction of response to cardiac resynchronization therapy.

AIMS: We directly compared TomTec and QLAB software packages for the three-dimensional echocardiographic (3DE) assessment of left ventricular (LV) dyssynchrony including their ability to predict response to cardiac resynchronization therapy (CRT) in patients with ischaemic and non-ischaemic cardiomyopathy. METHODS AND RESULTS: A total of 140 heart failure patients with the LVEF ≤35% and 60 healthy volunteers underwent 3DE. A subgroup of 60 patients underwent CRT and were evaluated before and 6-12 months after implantation. The systolic dyssynchrony index (SDI) was derived from the dispersion of time to minimum regional volume for all 16 LV segments and measured with both software packages and compared using Pearson's correlation and Bland-Altman analysis. Measurements of SDI were significantly higher using TomTec compared with QLAB in both patients (10.9 ± 3.8 vs. 9.7 ± 3.9, P < 0.001) and healthy volunteers (4.1 ± 0.8 vs. 2.4 ± 1, P < 0.001), with large biases and wide limits of agreement. A moderate correlation (r = 0.65, P < 0.001) was observed between both software packages in patients while their inter-observer and intra-observer reliability were good. Of the 60 patients undergoing CRT, reverse remodelling as a measure of response was observed in 41 patients (68%). The optimal SDI cut-off value to predict response to CRT was higher for TomTec than for QLAB (8.8 vs.7.3%, P < 0.001) and demonstrated better sensitivity and specificity (93 and 61%, respectively) compared with QLAB (88 and 33%, respectively). Response prediction in patients with non-ischaemic cardiomyopathy was excellent with a sensitivity and specificity of 95 and 100% for TomTec and 70 and 83% for QLAB using similar cut-off values of 9.1 and 9.2%, respectively. CONCLUSION: Different 3DE software packages for the assessment of mechanical dyssynchrony should not be used interchangeably until better software standardization is achieved. Dyssynchrony assessment with 3DE for the prediction of response to CRT seems particularly useful in patients with non-ischaemic cardiomyopathy.

Comparison between three-dimensional speckle-tracking echocardiography and cardiac magnetic resonance imaging for quantification of left ventricular volumes and function.

AIMS: We evaluated the accuracy of three-dimensional speckle-tracking echocardiography (3DSTE) to evaluate left ventricular (LV) volumes, ejection fraction (EF), and global circumferential strain (CS) in comparison with cardiac magnetic resonance imaging (MRI) in a healthy population. METHODS AND RESULTS: A total of 45 out of 50 consecutive healthy subjects (38 males, age 45 ± 15 years) successfully underwent both 3DSTE and MRI on the same day. Three-dimensional echocardiography data sets were analysed using speckle tracking to measure LV end-diastolic and end-systolic volumes, EF, and global CS. With MRI, the method of discs approximation was used to obtain volumes and the EF, whereas CS was acquired using myocardial tissue tagging. Inter-technique comparisons included regression and the Bland-Altman analysis. For quantification of LV volumes, 3DSTE correlated well with MRI (r: 0.75-0.81), but volumes were significantly underestimated with relatively large biases (13-34 mL) and wide limits of agreement (SD: 11-25 mL). However, excellent accuracy was revealed for measurement of EF by 3DSTE with a good correlation (r: 0.91), minimal bias, and narrow limits of agreement (0.6 ± 1.7%) compared with MRI. For measurement of CS, a large mean bias was found between techniques (10.0%), despite narrow limits of agreement (SD: 1.7%) and a good correlation between techniques (r: 0.80). CONCLUSION: Although 3DSTE-derived LV volumes are underestimated in most patients compared with MRI, measurement of the LVEF revealed excellent accuracy. Measurements of CS were systematically greater (i.e. more negative) with 3DSTE than MRI, which likely reflects various inter-technique differences that preclude direct comparability of their measurements.

Reliability of left ventricular volumes and function measurements using three-dimensional speckle tracking echocardiography.

AIMS: Although the accuracy of three-dimensional speckle tracking echocardiography (STE) to quantify left ventricular (LV) volumes and function has been demonstrated, its reliability has not been studied in great detail. The aim of the study was to determine inter-observer, intra-observer, and test-retest reliability of echocardiographic measurements of LV volumes and function using three-dimensional STE. METHODS AND RESULTS: A total of 140 consecutive patients presenting for routine echocardiographic examination underwent three-dimensional STE. Twenty-three of the 140 patients (16%) were excluded from the analysis due to atrial fibrillation or insufficient image quality. In the remaining 117 patients [69 males, age 59 ± 16 years, ejection fraction (EF) 51 ± 13%], intra-observer and inter-observer reliability of LV volumes, EF, and global and segmental strain measurements was determined, whereas test-retest reliability was assessed in a subgroup of 50 patients. LV volumes and EF measurements demonstrated good reliability [intraclass correlation coefficient (ICC): 0.85-0.99; standard error of measurement (SEM): 3.1-9.2 mL and 1.7-4.0%, respectively]. Reliability of global circumferential strain measurements (ICC: 0.85-0.97; SEM: 1.4-2.6%) was superior to longitudinal (ICC: 0.66-0.92; SEM: 1.0-2.1%) and radial strain measurements (ICC: 0.52-0.88; SEM: 4.4-8.1%), with similar results found for segmental strain measurements (P < 0.001 for all). Reliability was not significantly affected by the image quality or temporal resolution of 3D data sets for any parameter. CONCLUSION: Good intra-observer, inter-observer, and test-retest reliability support the use of three-dimensional STE for routine evaluation of LV volumes and EF. Global and segmental circumferential strain measurements also demonstrate high reliability, whereas analysis by a single observer is currently recommended for longitudinal and radial strain due to limited inter-observer and test-retest reliability.

Comparison between direct volumetric and speckle tracking methodologies for left ventricular and left atrial chamber quantification by three-dimensional echocardiography.

In an era of rapidly expanding and evolving 3-dimensional echocardiographic (3DE) technology, 1 of the issues facing the 3DE quantification of chamber volumes and function is that different software vendors use different methodologies and algorithms. The aim of this study was to evaluate the comparability and reproducibility of 3DE direct volumetric and speckle-tracking methods for left ventricular (LV) and left atrial (LA) chamber quantification. A total of 120 subjects (mean age 53 ± 17 years, 65% men), including 88 unselected patients and 32 healthy volunteers, underwent 3DE acquisitions and analysis using direct volumetric and speckle-tracking methods successively. Measurements of LV and LA volumes and LV function were compared between the 2 3DE methods. Additionally, intraobserver and interobserver reproducibility was assessed in 40 randomly selected patients. Measurements of LV end-diastolic volume, end-systolic volume, and ejection fraction by 3DE direct volumetric and 3DE speckle-tracking methods were comparable, with good correlations (r = 0.98, r = 0.98, and r = 0.87, respectively), small biases, and narrow limits of agreement (-1 ± 8 ml, -1 ± 8 ml, and 0 ± 6%, respectively). For measurements of LA end-systolic volume and end-diastolic volume, similar correlations (r = 0.96 for both), small biases, and narrow limits of agreement (-2 ± 6 and -1 ± 5 ml, respectively) were found between the 2 methods. Intraobserver and interobserver reproducibility for LV and LA quantification were comparable for the 2 methods. In conclusion, 3DE direct volumetric and speckle-tracking methods give comparable and reproducible quantification of LV and LA volumes and function, making interchangeable application a viable option in daily clinical practice.

Three-dimensional speckle tracking echocardiography for automatic assessment of global and regional left ventricular function based on area strain.

OBJECTIVE: We evaluated the ability of a novel automatic index based on area strain to reliably quantify global and regional left ventricular (LV) function and accurately identify wall motion (WM) abnormalities using three-dimensional speckle tracking echocardiography. METHODS: A total of 140 consecutive patients underwent two- and three-dimensional echocardiography. Segmental WM assessment by area strain was compared with visual assessment of two-dimensional images by two experienced echocardiographers. For global LV function assessment, area strain was validated against LV ejection fraction (EF) and wall motion score index (WMSI). Observer reliability was assessed in all patients, whereas test-retest reliability was evaluated in a subgroup of 50 randomly selected patients. Normal reference values of area strain were determined in 56 healthy subjects. RESULTS: Agreement of WM scores between area strain and visual assessment was found in 94% of normal, 55% of hypokinetic, and 91% of akinetic segments (κ-coefficient 0.88). Sensitivity, specificity, and accuracy of area strain to distinguish abnormal segments from normal segments were 91%, 96%, and 94%, respectively. In regard to global LV function assessment, area strain was highly correlated with EF and WMSI (r = 0.91 and 0.88, respectively). Observer and test-retest reliability of area strain for quantitative assessment of global and regional LV function were good to excellent (all intraclass correlation coefficients ≥0.77). Intraobserver and interobserver reliability of semiquantitative segmental WM analysis by area strain (κ-coefficients 0.87 and 0.73) were comparable to visual assessment by experienced echocardiographers (0.85 and 0.69, respectively). CONCLUSION: Area strain represents a promising novel automatic index that may provide an accurate and reproducible alternative to current echocardiographic standards for quantitative assessment of global and regional LV function. Area strain seems to adequately identify regional wall motion abnormalities compared with the clinical standard of visual assessment by experienced echocardiographers.