Characterizations and Inkjet Printing of Carbon Black Electrodes for Dielectric Elastomer Actuators.

Dielectric elastomer actuators (DEAs) have been proposed as a promising technology for developing soft robotics and stretchable electronics due to their large actuation. Among available fabrication techniques, inkjet printing is a digital, mask-free, material-saving, and fast technology, making it versatile and appealing for fabricating DEA electrodes. However, there is still a lack of suitable materials for inkjet-printed electrodes. In this study, multiple carbon black (CB) inks were developed and tested as DEA electrodes inkjet-printed on acrylic membranes (VHB). Triethylene glycol monomethyl ether (TGME) and chlorobenzene (CLB) were selected to disperse CB. The inks' stability, particle size, surface tension, viscosity, electrical resistance, and printability were characterized. The DEA with Ink-TGME/CLB (mixture solvent) electrodes obtained 80.63% area strain, a new benchmark for the DEA actuation with CB powder electrodes on VHB. The novelty of this work involves the disclosure of a new ink recipe (TGME/CLB/CB) for inkjet printing that can obtain stable drop formations with a small nozzle (17 × 17 µm), high resolution (∼25 µm, approaching the limit of drop-on-demand inkjet printing), and the largest area strain of DEAs under similar conditions, distinguishing this contribution from the previous works, which is important for the fabrication and miniaturization of DEA-based soft and stretchable electronics.

Association of left ventricular global area strain derived from resting 3D speckle-tracking echocardiography and exercise capacity in individuals undergoing treadmill exercise test.

Background: Left ventricular (LV) global area strain (GAS) is a novel index derived from resting 3D speckle-tracking echocardiography (STE), and its clinical significance has rarely been studied. We examined the association of LV GAS and exercise capacity in a health check-up population. Methods: We recruited 94 symptom-free participants (52.2 ± 11.7 years, 62.8% male) without substantial structural heart disease or coronary heart diseases who were undergoing a routine health examination. All participants underwent resting echocardiography and symptom-limited treadmill exercise test according to the Bruce protocol. Four strain parameters were obtained from the analysis, namely 3D GAS (GAS3d), global longitudinal strain, global circumferential strain, and global radial strain. Results: After multivariate analysis for factors of exercise time, we observed a significant association in LV GAS3d (P < 0.001). We divided participants into preserved and impaired exercise capacity groups according to the cutoff value of 8 metabolic equivalent of tasks. LV GAS3d (OR 1.24, 95% CI 1.10-1.39, P < 0.001) was an independent predictor of impaired exercise capacity and the optimal cut-off value was -19.96% at a sensitivity of 77.8% and at a specificity of 92.1%. LV GAS3d could improve the discriminatory power of exercise capacity in individuals with early mitral filling velocity to average mitral annulus velocity ratio (E/e') ≥ 8. Conclusions: LV GAS3d was significantly associated with exercise time and exhibited incremental predictive value on E/e' for exercise capacity in participants undergoing treadmill exercise test.

Structural Health Monitoring of Fatigue Cracks for Steel Bridges with Wireless Large-Area Strain Sensors.

This paper presents a field implementation of the structural health monitoring (SHM) of fatigue cracks for steel bridge structures. Steel bridges experience fatigue cracks under repetitive traffic loading, which pose great threats to their structural integrity and can lead to catastrophic failures. Currently, accurate and reliable fatigue crack monitoring for the safety assessment of bridges is still a difficult task. On the other hand, wireless smart sensors have achieved great success in global SHM by enabling long-term modal identifications of civil structures. However, long-term field monitoring of localized damage such as fatigue cracks has been limited due to the lack of effective sensors and the associated algorithms specifically designed for fatigue crack monitoring. To fill this gap, this paper proposes a wireless large-area strain sensor (WLASS) to measure large-area strain fatigue cracks and develops an effective algorithm to process the measured large-area strain data into actionable information. The proposed WLASS consists of a soft elastomeric capacitor (SEC) used to measure large-area structural surface strain, a capacitive sensor board to convert the signal from SEC to a measurable change in voltage, and a commercial wireless smart sensor platform for triggered-based wireless data acquisition, remote data retrieval, and cloud storage. Meanwhile, the developed algorithm for fatigue crack monitoring processes the data obtained from the WLASS under traffic loading through three automated steps, including (1) traffic event detection, (2) time-frequency analysis using a generalized Morse wavelet (GM-CWT) and peak identification, and (3) a modified crack growth index (CGI) that tracks potential fatigue crack growth. The developed WLASS and the algorithm present a complete system for long-term fatigue crack monitoring in the field. The effectiveness of the proposed time-frequency analysis algorithm based on GM-CWT to reliably extract the impulsive traffic events is validated using a numerical investigation. Subsequently, the developed WLASS and algorithm are validated through a field deployment on a steel highway bridge in Kansas City, KS, USA.

Nicorandil Improves Left Ventricular Myocardial Strain in Patients With Coronary Chronic Total Occlusion.

Background: Nicorandil is recommended as a second-line treatment for stable angina; however, randomized-controlled trials to evaluate the benefit of nicorandil for patients with chronic total occlusion (CTO) are lacking. Objective: To determine whether nicorandil can improve left ventricular (LV) myocardial strain in patients with CTO. Methods: Patients with CTO were included and randomized to the nicorandil group (n = 31) and the control group (n = 30). Nicorandil was given orally at 15 mg/day for 3 months in the nicorandil group. Three-dimensional speckle-tracking echocardiography and the Seattle Angina Questionnaire (SAQ) survey were performed at baseline and at 3 months. The primary study endpoint was the LV global area strain (GAS) at 3 months. Results: The nicorandil and the control groups were well-matched at baseline, including the mean GAS and SAQ scores. At 3 months, GAS in the nicorandil group was significantly higher than that in the control group (-23.7 ± 6.3% vs. -20.3 ± 5.6%, respectively; p = 0.033). There were no significant differences in LV global longitudinal strain, global circumferential strain, global radial strain, LV ejection fraction, LV end-diastolic volume, and LV end-systolic volume at 3 months between the two groups. At 3 months, the SAQ scores for angina stability, angina frequency, and treatment satisfaction in the nicorandil group were significantly higher than those in the control group. Conclusion: Nicorandil treatment can improve GAS and angina symptoms in patients with CTO. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT05087797.

A Comparison Between Two-Dimensional and Three-Dimensional Regional and Global Longitudinal Strain Echocardiography to Evaluate Complex Coronary Lesions in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome.

Introduction A preliminary assessment of patients who suffer from severe and complex coronary artery lesions, such as three-vessel disease and/or a left main (LM) artery lesion, plays a critical contribution in determining prognosis and treatment plans for non-ST-segment elevation acute coronary syndrome (NSTE-ACS). Therefore, a pre-angiography (i.e., before angiography) predictor was required to cost-effectively evaluate severe and complex coronary lesions to efficiently direct our subsequent dealing. Aim This study aimed to compare two-dimensional (2D) and three-dimensional (3D) global longitudinal strain (GLS) at the regional level to assess extremely complicated coronary lesions using the SYNTAX score as a standard of reference in 100 patients with NSTE-ACS. Materials and methods This research included 100 patients with non-ST-segment elevation acute coronary syndrome who presented at the Cardiology Department at Fayoum University from December 2019 to July 2020. All patients underwent a complete history and physical examination, hemoglobin A1c (HbA1c), lipid profile, creatinine assessment, 12-lead electrocardiogram (ECG), and transthoracic echocardiography (TTE) to detect global and regional longitudinal strain by 2D and 3D speckle-tracking echocardiography (STE). Coronary angiography was done on all patients within 24 hours of admission after acquiring echo images. Then, the results of 2D and 3D regional and global longitudinal strain (GLS) to predict the severity and coronary lesion complexity in terms of the SYNTAX score were compared. Results This study revealed that 2D GLS was -12.10 ± 3.51, which is significantly higher than 3D GLS of -11.64 ± 4.05 (p < 0. 001). The left anterior descending coronary artery (LAD) and left circumflex artery (LCX) territories revealed a significantly higher value using 2D regional longitudinal strain (-11.13 ± 4.47 and -12.54 ± 4.11, respectively) than using 3D regional longitudinal strain (-10.84 ± 5.18 and -12.05 ± 4.29, respectively) (p= 0.017 and p < 0.001, respectively). There were significantly lower 2D GLS, 3D GLS, global circumferential strain (GCS), area strain, and global radial strain (GRS) in the intermediate and high score group than in the low score group of patients (p < 0.001 for all). Conclusion 2D and 3D strain echocardiography including GLS, GCS, GRS, and area strain are a noninvasive and rapid tool with clinical utility for evaluating coronary lesions in patients with NSTE-ACS. They can be routinely used to diagnose and stratify high-risk patients with NSTE-ACS, thereby potentially resulting in improved patient assessment. GLS as measured by 2D and 3D STE at minimal effort is a significant risk factor for patients with complex NSTE-ACS. In NSTE-ACS cases, the GLS absolute value is significantly associated with the degree of complexity of coronary artery lesions.

Non-Invasive Estimation of Left Ventricular Filling Pressure Based on Left Atrial Area Strain Measured With Transthoracic 3-Dimensional Speckle Tracking Echocardiography in Patients With Coronary Artery Disease.

Background: Chronic elevation of left ventricular (LV) diastolic pressure (DP) or chronic elevation of left atrial (LA) pressure, which is required to maintain LV filling, may determine LA wall deformation. We investigated this issue using transthoracic 3-dimensional speckle tracking echocardiography (3D-STE). Methods and Results: We retrospectively enrolled 75 consecutive patients with sinus rhythm and suspected stable coronary artery disease who underwent diagnostic cardiac catheterization and 3D-STE on the same day. We computed the global LA wall area change ratio, termed the global LA area strain (GLAS), during both the reservoir phase (GLAS-r) and contraction phase (GLAS-ct). The LVDP at end-diastole (LVEDP) and mean LVDP (mLVDP) were measured with a catheter-tipped micromanometer in each patient. GLAS-r and GLAS-ct were significantly correlated with both mLVDP (r=-0.70 [P<0.001] and r=0.71 [P<0.001], respectively) and LVEDP (r=-0.63 [P<0.001] and r=0.65 [P<0.001], respectively). In receiver operating characteristic curve analysis, the optimal cut-off values for diagnosing elevated LVEDP (≥16 mmHg) were 75.7% (sensitivity 83.3%, specificity 77.8%) for GLAS-r and -43.1% (sensitivity 90.0%, specificity 80.0%) for GLAS-ct. Similarly, for diagnosing elevated mLVDP (≥12 mmHg), the cut-off values were 63.6% (sensitivity 88.9%, specificity 80.3%) for GLAS-r and -26.2% (sensitivity 66.7%, specificity 97.0%) for GLAS-ct. Conclusions: We showed that 3D-STE-derived GLAS values could be used to non-invasively diagnose elevated LV filling pressure.

Right ventricular area strain from 3-dimensional echocardiography: Mechanistic insight of right ventricular dysfunction in pediatric pulmonary hypertension.

BACKGROUND: Right ventricular (RV) function is a major contributor to the outcome of pulmonary arterial hypertension (PAH). Adult studies demonstrated that regional and global changes in RV deformation are prognostic in PAH using 3-dimensional echocardiography (3DE). However, regional and global dynamic changes in RV mechanics have not been described in pediatric PAH. We compared 3DE RV regional and global deformation between pediatric patients who had associated PAH with congenital heart disease (APAH-CHD), pediatric patients who had idiopathic PAH (IPAH), and normal controls, and evaluated the clinical outcomes. METHODS: A total of 48 controls, 47 patients with APAH-CHD, and 45 patients with IPAH were evaluated. 3DE RV sequences were analyzed and post-processed to extract global and regional deformation (circumferential, longitudinal, and area strain). Statistical analyses compared the sub-groups on the basis of global and regional deformation, and outcome analysis was performed. RESULTS: Patients with PAH had significantl8y different global and regional deformation (p < 0.001) compared with controls. Patients with APAH-CHD and and those with IPAH significantly differed in global circumferential strain (p < 0.010), area strain (inlet septum, p = 0.041), and circumferential strain at the inlet septum (p < 0.019), apex free wall (p < 0.004), and inlet free wall (p < 0.004). Circumferential strain at the inlet free wall and circumferential, longitudinal, and area strain at the apex free wall were predictors of adverse events. CONCLUSIONS: RV regional and global strain differ between controls and pediatric patients with PAH. RV apical free-wall area strain provides insight into the mechanism of RV dysfunction in pediatric patients with PAH, with regional strain emerging as outcome predictors, suggesting that this novel measure may be considered as a future measure of RV function.

A Pilot Study to Predict Future Cardiovascular Events by Novel Four-dimensional Echocardiography Global Area Strain in ST-Elevation Myocardial Infarction Patients Managed by Primary Percutaneous Coronary Intervention.

CONTEXT: Four-dimensional speckle-tracking echocardiography (4D-STE) is ideal to accurately assess myocardial deformation. The novel 4D global area strain (GAS) uses global longitudinal and global circumferential strains (GCSs) to detect subtle changes in myocardium. AIMS: The aim of this study was to determine the predictive value of 4D strain echocardiography for major adverse cardiovascular events (MACEs) in ST-elevation acute myocardial infarction (STEMI) patients after successful reperfusion by primary percutaneous coronary intervention (PCI). SETTINGS AND DESIGN: This was a longitudinal study at a single center. PATIENTS AND METHODS: We enrolled 170 patients who underwent successful primary PCI. Each patient was evaluated with 2D echocardiography and 4D echocardiography with 4D strain parameters and followed up over a year for the occurrence of MACE. STATISTICAL ANALYSIS USED: Chi-square test, independent t-tests, and multivariate logistic regression analysis were used. RESULTS: Over 1 year of follow-up, 32 MACE were recorded. Patients with MACE were more likely to have had percutaneous transluminal coronary angioplasty done during the index primary PCI intervention, multivessel coronary artery disease, higher left ventricular end-diastolic and end-systolic dimensions (left ventricle end diastolic dimension (LVEDD) and left ventricle end systolic dimension (LVESD), respectively), lower 2D left ventricular ejection fraction (LVEF), higher wall motion score index, higher baseline heart rate, higher end-diastolic and end-systolic volumes, lower 3D-LVEF, higher 4D global longitudinal strain, 4D-GCS, 4D-GAS, and lower 4D global radial strain (4D-GRS) (P < 0.005 for all parameters). The most powerful predictor for MACE among our study population is 4D-GAS, with the best cutoff value of 4D-GAS >-17 (P = 0.008; odds ratio = 20.668; confidence interval = 2.227-191.827). CONCLUSIONS: The novel 4D-GAS echocardiography predicts adverse clinical events in STEMI patients managed by successful primary PCI.

Initial application of three-dimensional speckle-tracking echocardiography to detect subclinical left ventricular dysfunction and stratify cardiomyopathy associated with Duchenne muscular dystrophy in children.

Three-dimensional (3D) speckle-tracking echocardiography (STE) is a new imaging modality used for quantitative analysis of left ventricular (LV) function. The aim of this study is to assess the value of 3D STE in early detection of subclinical myocardial involvement in children with Duchenne muscular dystrophy (DMD). Fifty-six children with DMD (mean age, 8.8 ± 1.9 years) and 31 age-matched control subjects were studied. Patients were subdivided into two groups by age: ≤ 8 or > 8 years. Standard echocardiography examinations were performed to measure LV size and ejection fraction (EF). 3D STE was performed to assess LV 3D global strain and LV end-diastolic volume (EDV), end-systolic volume (ESV), and EF. Standard and 3D echocardiography measures were compared between children with DMD and those in the control group as well as between different patient groups. The areas under the receiver-operating characteristic (ROC) curve were calculated to determine the capability of 3D global strain indices to discriminate between patients and control subjects. No significant difference was detected in either LVEF derived from M-mode or 3D echocardiography between the two groups, and they were both within the normal range. Compared with control subjects, children with DMD had significantly reduced LV 3D global longitudinal strain (GLS; - 16.6 ± 4.7 vs. - 19.5 ± 3.7, p = 0.003), global circumferential strain (GCS; - 13.7 ± 2.9 vs. - 15.8 ± 2.6, p = 0.001), global radial strain (GRS; 42.5 ± 9.7 vs. 50.3 ± 10.4, p = 0.001), and global area strain (GAS; - 25.3 ± 4.9 vs. - 30.7 ± 4.1, p = 0.000). The older DMD children (age > 8 years) had lower GLS (- 15.1 ± 4.43 vs. - 18.6 ± 4.35, p < 0.05), GCS (- 12.8 ± 3.48 vs. - 14.8 ± 2.83, p < 0.001), GAS (- 23.8 ± 4.7 vs. - 29.0 ± 5.4, p < 0.001), and GRS (40.7 ± 8.8 vs. 47.3 ± 11.5, p < 0.05) than younger patients (age ≤ 8 years). The AUC of GAS was 0.80, and the cutoff value of - 29.5 had a sensitivity of 85.7% and a specificity of 71.0% for differentiating DMD patients from control. 3D speckle-tracking echocardiography is useful for detecting subclinical myocardial dysfunction and stratifying cardiomyopathy in children with DMD.

Predictive Value of Four-Dimensional Strain Echocardiography for Adverse Cardiovascular Outcomes in ST-Elevation Myocardial Infarction Patients Treated with Primary Percutaneous Coronary Intervention.

OBJECTIVES: To investigate the predictive value of four-dimensional (4D) strain echocardiography for major adverse cardiovascular events (MACE) in ST-elevation acute myocardial infarction (STEMI) patients. METHODS: Consecutive STEMI patients who underwent successful primary coronary interven tion (PCI) were enrolled and followed, with 2D and 4D strain echocardiography performed within 1 week after PCI. RESULTS: Twenty-six first MACE were recorded in 81 patients who finished a ∼3.0 year follow-up. Compared with those without MACE, subjects with MACE were more likely to have anterior MI (73.08 vs. 38.18%, p = 0.003), significantly decreased 2D left ventricular ejection fraction (2DLVEF) and 4DLVEF (all p < 0.05), as well as an overtly compromised 4D strain parameters. The prediction models incorporating infarct location with either 2DLVEF or 4D strain parameters were then developed. Model comparisons revealed that the global area strain (GAS)-based model had the highest discriminative capacity (c statistics = 0.774) and was well calibrated for MACE. Additionally, the clinical utility of the GAS-based prediction model was verified by decision curve analysis showing a consistent positive and larger net benefit compared to the 2DLVEF-based model. CONCLUSIONS: Our data support a superiority of 4D strain echocardiography over conventional 2D echocardiography, especially GAS, for risk stratification in STEMI patients after successful primary PCI.

Quantifying Patterns of Smooth Muscle Motility in the Gut and Other Organs With New Techniques of Video Spatiotemporal Mapping.

The uses and limitations of the various techniques of video spatiotemporal mapping based on change in diameter (D-type ST maps), change in longitudinal strain rate (L-type ST maps), change in area strain rate (A-type ST maps), and change in luminous intensity of reflected light (I-maps) are described, along with their use in quantifying motility of the wall of hollow structures of smooth muscle such as the gut. Hence ST-methods for determining the size, speed of propagation and frequency of contraction in the wall of gut compartments of differing geometric configurations are discussed. We also discuss the shortcomings and problems that are inherent in the various methods and the use of techniques to avoid or minimize them. This discussion includes, the inability of D-type ST maps to indicate the site of a contraction that does not reduce the diameter of a gut segment, the manipulation of axis [the line of interest (LOI)] of L-maps to determine the true axis of propagation of a contraction, problems with anterior curvature of gut segments and the use of adjunct image analysis techniques that enhance particular features of the maps.

Left Ventricular Wall Stress Is Sensitive Marker of Hypertrophic Cardiomyopathy With Preserved Ejection Fraction.

Hypertrophic cardiomyopathy (HCM) patients present altered myocardial mechanics due to the hypertrophied ventricular wall and are typically diagnosed by the increase in myocardium wall thickness. This study aimed to quantify regional left ventricular (LV) shape, wall stress and deformation from cardiac magnetic resonance (MR) images in HCM patients and controls, in order to establish superior measures to differentiate HCM from controls. A total of 19 HCM patients and 19 controls underwent cardiac MR scans. The acquired MR images were used to reconstruct 3D LV geometrical models and compute the regional parameters (i.e., wall thickness, curvedness, wall stress, area strain and ejection fraction) based on the standard 16 segment model using our in-house software. HCM patients were further classified into four quartiles based on wall thickness at end diastole (ED) to assess the impact of wall thickness on these regional parameters. There was a significant difference between the HCM patients and controls for all regional parameters (P < 0.001). Wall thickness was greater in HCM patients at the end-diastolic and end-systolic phases, and thickness was most pronounced in segments at the septal regions. A multivariate stepwise selection algorithm identified wall stress index at ED (σ i,ED ) as the single best independent predictor of HCM (AUC = 0.947). At the cutoff value σ i,ED < 1.64, both sensitivity and specificity were 94.7%. This suggests that the end-diastolic wall stress index incorporating regional wall curvature-an index based on mechanical principle-is a sensitive biomarker for HCM diagnosis with potential utility in diagnostic and therapeutic assessment.

Comprehensive computational assessment of blood flow characteristics of left ventricle based on in-vivo MRI in presence of artificial myocardial infarction.

BACKGROUND: Understanding the effects of cardiac diseases on the heart's functionality which is the purpose of many biomedical researches, directly affects the diagnostic and therapeutic methods. Myocardial infarction (MI) is a common complication of cardiac ischemia, however, the impact of MI on the left ventricle (LV) flow patterns has not been widely considered by computational fluid dynamics studies thus far. METHODS: In this study, we present an insightful numerical method that creates an artificial MI on an image-based fluid-structure interactional model of normal LV to investigate its influence on the flow in comparison with the normal case. Seventeen different models were developed to evaluate the effects of location, percentage, myocardial material properties and dilation size of MI on the LV's performance, area strain, wall displacement, pressure-volume loop, wall shear stress and velocity field. RESULTS: The results show that MI considerably changes blood flow features which are fully dependent on MI parameters. For the case of constant MI location, the effect of a decrease of infarcted myocardium stiffness, increase of dilation size and increase of MI percentage are mostly similar. Although the location differences of MI under other constant conditions have similar impact on the ejection fraction, they also lead to dissimilar variations in the LV flow pattern and other indicators. CONCLUSIONS: The presented model showed a capable computational method for investigating various mechanical MI conditions with respect to cardiac flow pattern. The perspective of this model development seems to be an applicable tool for MI clinical diagnosis and prediction of complications related to MI.

Intravascular ultrasound elastography analysis of the elastic mechanical properties of atherosclerotic plaque.

To assess the elastic mechanical properties of atherosclerotic plaque with different morphological properties by intravascular ultrasound elastography (IVUSE). 30 purebred New Zealand rabbits were fed a high-cholesterol diet; the abdominal aorta endothelium was balloon-injured after 2 weeks; at week 12, 2 plaques with moderate echo from each rabbit were chosen for in situ imaging, and 2 consecutive frames near the end-diastole images in situ were used to construct an IVUS elastogram. Shear strain (SS) and area strain (AS) were greater for eccentric than centripetal plaque (SS: 2.65(2.45)% vs. 1.79 ± 0.97%, p < 0.05; AS: 4.81(4.99)% vs. 3.23 ± 1.75%, p < 0.05) but were lower with low than high plaque burden (SS: 2.14 ± 0.37% vs. 3.40 ± 0.34%, p < 0.05; AS: 3.88 ± 0.60% vs. 5.81 ± 0.54%, p < 0.05). SS and AS were significantly greater for plaque with negative than no remodeling (SS: 3.98 ± 1.53% vs. 1.82(1.40)%, p < 0.017; AS: 6.94 ± 2.24% vs. 2.59(2.87)%, p < 0.017) and were found correlated with eccentric index and plaque burden (R2 = 0.365 and R2 = 0.359, both p < 0.05). Plaques associated with eccentricity, high plaque burden and negative remodeling showed greater strain than those with centripetalism, low plaque burden and positive remodeling. Eccentric index and plaque burden may be useful to predict the elastic stability of plaque.

Relationship between plaque burden and area strain of atherosclerosis with intravascular ultrasound elastography / 中国医学影像技术

Objective To assess the relationship between plaque burden (PB) and area strain (AS) by intravascular ultrasonic elastography (IVUSE).Methods Forty purebred New Zealand rabbits were fed with a high-cholesterol diet.And the abdominal aorta endothelium was balloon-injured after 2 weeks.At the end of the 12th week,2 plaques with moderate echo from each rabbit were chosen for in situ imaging,and 2 consecutive frames near the end-diastole images in situ were used to construct an IVUS elastogram.Cross-sectional external elastic membrane area (EEMare),lumen area (Lumenarea),plaque area (PA),PB,external elastic membrane volume (EEMvolume),lumen volume (Lumenvolume),plaque volume (PV),plaque volume burden (PVB),maximal plaque thickness (Tmax) and minimal plaque thickness (Tmin),eccentric index (EI),remodeling index (RI) and AS were measured and calculated,respectively.According to the PB,the plaques were divided into low PB group (PB≤40 ％) and high PB group (PB＞ 40 ％).The differences of all above parameters between the two groups were compared,and the relationship between the plaque morphological and mechanical parameters were analyzed.Results PA,PV,PB,PVB,Tmin,Tmax,Lumenarea,Lumenvolume and EI were different between the 2 groups (all P＜0.01).On stepwise multiple regression analysis,the regression equation were built,(Y)=-6.921+10.430X1 +12.207X2((Y):AS,X1:EI,X2:PB,R2 =0.272,P＜0.001).After eliminating the effect of EI on the AS,the lower PB group had obviously smaller AS than higher PB group (P =0.010).Conclusion The PB has effect on plaque mechanical stability.The plaques with higher burden are more vulnerable than those with lower burden.

Relationship between plaque burden and area strain of atherosclerosis with intravascular ultrasound elastography / 中国医学影像技术

Objective To assess the relationship between plaque burden (PB) and area strain (AS) by intravascular ultrasonic elastography (IVUSE).Methods Forty purebred New Zealand rabbits were fed with a high-cholesterol diet.And the abdominal aorta endothelium was balloon-injured after 2 weeks.At the end of the 12th week,2 plaques with moderate echo from each rabbit were chosen for in situ imaging,and 2 consecutive frames near the end-diastole images in situ were used to construct an IVUS elastogram.Cross-sectional external elastic membrane area (EEMare),lumen area (Lumenarea),plaque area (PA),PB,external elastic membrane volume (EEMvolume),lumen volume (Lumenvolume),plaque volume (PV),plaque volume burden (PVB),maximal plaque thickness (Tmax) and minimal plaque thickness (Tmin),eccentric index (EI),remodeling index (RI) and AS were measured and calculated,respectively.According to the PB,the plaques were divided into low PB group (PB≤40 ％) and high PB group (PB＞ 40 ％).The differences of all above parameters between the two groups were compared,and the relationship between the plaque morphological and mechanical parameters were analyzed.Results PA,PV,PB,PVB,Tmin,Tmax,Lumenarea,Lumenvolume and EI were different between the 2 groups (all P＜0.01).On stepwise multiple regression analysis,the regression equation were built,(Y)=-6.921+10.430X1 +12.207X2((Y):AS,X1:EI,X2:PB,R2 =0.272,P＜0.001).After eliminating the effect of EI on the AS,the lower PB group had obviously smaller AS than higher PB group (P =0.010).Conclusion The PB has effect on plaque mechanical stability.The plaques with higher burden are more vulnerable than those with lower burden.

Research on the relationship between area strain and eccentric index of atherosclerotic plaques by intravascular ultrasonic elastography / 中华超声影像学杂志

Objective To assess the relationships between area strain (AS) and eccentric index (EI) of atherosclerotic plaques as seen by intravascular ultrasonic elastography (IVUSE),and to reveal the effect of EI on the plaques stability.Methods Forty purebred New Zealand rabbits were fed with a high-cholesterol diet;the abdominal aorta endothelium was balloon-injured after 2 weeks;at the end of week 12,2 plaques with moderate echo from each rabbit were chosen for in situ imaging,and 2 consecutive frames near the end-diastole images in situ were used to construct an IVUS elastogram.Results The eccentric plaques showed significantly greater area stain (AS) than the centripetal plaques [4.77(2.92,8.01)% vs 3.27(2.15,4.82)%,P=0.029] with smaller plaque area and plaque burden (P<0.05).The plaque AS was positively correlated with EI (r=0.392,P=0.003).The eccentric plaques showed significantly greater AS in the shoulder than in body [4.98(3.17,8.48)% vs 4.64(2.51,5.92)%,P=0.008].Conclusions The EI is one of influential factors on plaque AS.Eccentric plaques may be more vulnerable than centripetal plaques,especially in the shoulder of eccentric plaques which have greater AS than their body.

Impact of area strain by 3D speckle tracking on clinical outcome in patients after acute myocardial infarction.

BACKGROUND: Three-dimensional (3D) speckle tracking echocardiography (STE) has been developed to overcome the limitations of two-dimensional (2D) STE and has been applied in the several clinical settings. However, no data exist about the prognostic value of 3DSTE-based strain on clinical outcome after myocardial infarction (MI). This study was designed to investigate the prognostic value of area strain (AS) by 3D speckle tracking in predicting clinical outcome after acute MI. METHODS: We assessed 96 patients (62±14 years, 72% male) with acute MI and who had undergone a coronary angiography. Clinical parameters and conventional echocardiographic measurements including the left atrial (LA) size and tissue Doppler measurements were evaluated. The global left ventricular (LV) AS was measured using 3D speckle tracking software. The relationship between the AS and clinical outcome of death or hospitalization for heart failure (HF) was assessed. RESULTS: During a median follow-up of 33±10 months, primary endpoint of death or HF occurred in 12 patients (12.5%). AS was predictive of death or HF after adjustment for age, gender, peak CK-MB, LA volume, LV end-systolic volume, LV mass, the ratio of early mitral inflow velocity to early mitral annular velocity, and LV ejection fraction in a multivariate Cox model (HR 1.23, 95% CI 1.02-1.47, P=.03). In addition, AS added incremental value in predicting death or heart failure on a model based on clinical and standard echocardiographic measures (P=.008). CONCLUSION: AS is independently associated with increased risk of death or HF after acute MI, suggesting that it can be a useful prognostic parameter in the patients following MI.