Association of Aortic Distensibility and Left Ventricular Function in Patients With Stenotic Bicuspid Aortic Valve and Preserved Ejection Fraction: A CMR study

To determine the relationship between aortic distensibility and left ventricular (LV) remodeling, myocardial strain and blood biomarkers in patients with stenotic bicuspid aortic valve (BAV) and preserved ejection fraction (EF) by cardiovascular magnetic resonance (CMR). 43 stenotic BAV patients were prospectively selected for 3.0T CMR. Patients were divided into LV remodeling group (LV mass /volume ≥ 1.15, n=21) and non-remodeling group (LV mass/volume < 1.15, n=22). Clinical characteristics, biochemical data including cardiac troponin T(cTNT), N-terminal pro-B type natriuretic peptide (NT-proBNP) and creatine kinase isoenzyme were noted. Distensibility of middle ascending aorta (mid-AA) and proximal descending aorta, LV structural and functional parameters, global and regional myocardial strain were measured. Compared to non-remodeling group, LV remodeling group had significantly decreased LV global strain (radial: 26.04±8.70 % vs. 32.92±7.81 %, P=0.009; circumferential: -17.20±3.38 % vs. -19.65±2.34 %, P=0.008; longitudinal: -9.13±2.34 % vs. -11.63±1.99 %, P＜0.001), while radial and circumferential strain were significantly reduced at the base (radial: 28.52±9.47 % vs. 39.65±10.33 %, P=0.001; circumferential: -14.45±2.97 % vs. -17.22±2.38 %, P=0.002), longitudinal strain was significantly reduced at all regions (basal: -5.79±3.43 % vs. -8.65±2.42 %, P=0.003; mid: -8.62±2.21 % vs. -11.33±2.58 %, P=0.001; apical : -12.79±2.49 % vs. -15.04±2.20 %, P=0.003). In addition, mid-AA distensibility was independently associated with LV remodeling (β=-0.282, P=0.003), and it was also significantly correlated with LV global strain (radial: r=0.392, P=0.009; circumferential: r=-0.348, P=0.022; longitudinal: r=-0.333, P=0.029), cTNT (r=-0.333, P=0.029) and NT-proBNP (r= -0.440, P=0.003). In this cohort with stenotic BAV and preserved EF, mid-AA distensibility is found significantly associated with LV dysfunction, which may be an important factor for predicting adverse cardiovascular events and a potential therapeutic target to prevent heart failure.

The Correlation between the Right Ventricular Strain and the Severity of Right Coronary Artery Lesions in Patients with Stable Coronary Artery Disease

Background A recent study demonstrated that in patients with stable coronary artery disease who were indicated for coronary angiography and it resulted in single proximal RCA significant lesion and 2D echocardiography was normal, speckle tracking on RV free wall detected significant impact on its segments and its global strain. Aim of the Work: To correlate between the RV strain and the degree of RCA stenosis in patients with stable Angina. Methods: a prospective observational study done included large number of persons complaining of typical anginal pain indicated for coronary angiography. Conventional 2D TTE was done and we excluded patients with RV dysfunction or RV dilatation. Speckle tracking on RV was done before doing coronary angiography. Patients with single ostial, para ostial or proximal dominant RCA lesions were chose to correlate their degree of stenosis with right ventricular free wall and RV global strain speckle tracking. Also, control group with normal speckle tracking and normal coronary angiography was taken in the study. Data was collected & coded using Microsoft Office Excel Worksheet while statistical analysis was performed using statistical package for social sciences (SPSS) version Results: The study showed that regarding the Echocardiography parameters, there were statistically significant difference between the 2 groups regarding the B RVFW, MRVFW, APRVFW and GLsRV. Significant relation was detected between degree of the proximal RCA stenotic lesion and speckle tracking parameters of RVFW and GLsRV. Conclusion: RVFWLS and GLsRV has highly significant correlation with the degree of the proximal stenotic lesion.

Role of LA strain assessed by speckle tracking echocardiography in predicting patients who develop POAF after a coronary artery bypass surgery

Objectives To evaluate the correlation between left atrial dysfunction assessed by speckle tracking echocardiography and development of postoperative atrial fibrillation (POAF) in patients undergoing coronary artery bypass grafting. To determine the role of coronary risk factors in development of POAF. Method Patients undergoing CABG from January 2019 till June 2020 in Apollo institute, fulfilling the inclusion and exclusion criteria were included.Total of 200 patients were followed.They were subjected to LA strain and strain rate analysis by speckle tracking. Results The incidence of POAF in our study was 24% (n=48). The mean age of this study population was 59.13 years. The patients who developed POAF were older (68.5±9.048 vs 58.39±9.74 years, p value=0.05) than those with no POAF. POAF occurred in 2 phases. the highest proportion of POAF occurrence noticed on postoperative day 2. Among the total POAF cases 79.% occurred within the first 48 hours and 20.8% occurred later (p=0.001). Among the 48 patients who developed POAF, 5 of them developed recurrence during their hospital stay. They had reverted to sinus rhythm following anti-arrhythmic medication for a duration of &gt;24 hours, but went on to develop recurrence of AF at a later. 4 among them reverted to sinus rhythm at discharge while 1 continued to remain in AF at discharge.The duration of hospital stay for patients with POAF group was 10.4 days compared with 10.04 days for those without POAF. Similarly the post-operative stay in the hospital was 7.4 days for the POAF group and 7.04 days for the NO POAF.There was no added economic impact secondary to AF.Comparing the values of left atrial volume index of both the groups it was derived that the mean LAVI value of the POAF group was 26.84+3.654 ml/m2 and that for the NO POAF group was 26.6+3.037ml/m2. Though the patients with POAF had larger LA volume, the chi square test analysis did not yield any clinically significant relationship between LAVI and POAF in our study (p=0.3). The mean LA global strain for the patients with POAF was 29.73+3.695%. And for the patients with no POAF was 36.3+4.854%. LA global strain was reduced in patients who developed POAF (P&lt;0.001) which indicated a strong correlation between LA strain and POAF. Conclusion There is significant correlation between Global Left Atrial Strain and POAF in patients undergoing CABG (P&lt;0.001).There is no significant correlation between patient factors like age, BMI, and the conventional coronary risk factors with POAFThere is no significant correlation between the conventional echocardiographic parameters like LA diameter, LAVI, LVDD, LVSD, LVEF and transmitral flow velocities with POAF. To conclude, preoperative speckle tracking assessment of LA has a strong predictive role in determining the occurrence of POAF in patients undergoing Coronary artery bypass grafting surgery. FUNDunding Acknowledgement Type of funding sources: None.

Fibrosis biomarkers and global myocardial strain in the diagnosis and prediction of diastolic dysfunction in patients with myocardial infarction and preserved ejection fraction

Aim. To assess the correlation of fibrosis biomarkers with parameters of diastolic function (DF) in assessing global longitudinal strain in patients with ST-segment elevation myocardial infarction (STEMI) and preserved left ventricular ejection fraction (EF).Material and methods. We examined 50 patients (100%) with primary STEMI and preserved LVEF at the end of hospitalization. On the 1st day of MI, standard diagnostic investigations were carried out. On the 12th day, the serum concentration of procollagen type I carboxy-terminal propeptide (PICP), N-terminal propeptide of procollagen type III (PIIINP), and galectin-3 was determined, as well as echocardiography was performed to assess left ventricular DF. After 1 year, all participants underwent reassessment of PICP, PIIINP, and galectin-3 serum levels. Echocardiography was also performed with an assessment of DF and LV global longitudinal strain.Results. According to speckle-tracking echocardiography, LV global longitudinal strain was visualized in 30 patients (60%), who were included in the final analysis. In the rest of the patients (40%), the limitations did not allow the technique to be performed. During the hospitalization, signs of diastolic dysfunction (DD) were detected in 5 (16,6%) patients; after 1 year, their number increased by 7 (23,3%). During the 1-year follow-up, the total number of patients with echocardiographic signs of DD was 20 (67%). At the same time, global strain parameters indicated the presence of DD in 23 (77%) patients. However, comparison of the incidence of DD according to echocardiography and using the speckle-tracking technology did not show significant differences (p=0,283). Throughout the entire follow-up period, the concentration of the studied fibrosis markers significantly exceeded the control group values. We recorded associations of global strain parameters with biochemical markers of fibrosis and LV DF indicators.Conclusion. Fibrosis biomarkers (PICP, PIIINP, galectin-3), assessed in the subacute period of MI in patients with preserved EF, correlated with indicators of global myocardial strain, which indicates the potential value of their determination for predicting and detecting DD in the postinfarction period.

Numerical Analysis of the Crack Driving Force of Mismatched Girth Welded Pipes Subject to Large Plastic Deformations

Strength mismatched pipes with part-through cracks can suffer large plastic deformation from permanent ground deformations caused by geohazards. Thus, the crack driving force involved in engineering critical assessments plays an important role in guaranteeing pipeline integrity when pipes are subjected to complex loads induced by a hostile environment. In this paper, Python scripts are developed to generate up to 200 finite element models of strength mismatched pipes with various crack sizes under large plastic deformations based on the commercial software ABAQUS. The effects of crack length, crack depth, and strength mismatch factors on the evolution of crack tip opening displacement (CTOD) and global strain were investigated. An approximately linear relationship was observed in all cases tested with global strain values varying from 0.5% to 3%. Meanwhile, the value of the CTOD increased with the increase of crack length and crack depth, and decreased with increasing mismatch factor from the undermatch to the overmatch conditions. The effect of the crack depth on the CTOD is comparatively larger than the crack length, which presented an obvious change of the CTOD for deep cracks coupled with undermatched conditions. Overmatched welding only affected the value of CTOD slightly, while a drastic increase of CTOD value was observed for the undermatched welding conditions, especially for deep and long cracks.

Global strain-induced scalar potential in graphene devices

By mechanically distorting a crystal lattice it is possible to engineer the electronic and optical properties of a material. In graphene, one of the major effects of such a distortion is an energy shift of the Dirac point, often described as a scalar potential. We demonstrate how such a scalar potential can be generated systematically over an entire electronic device and how the resulting changes in the graphene work function can be detected in transport experiments. Combined with Raman spectroscopy, we obtain a characteristic scalar potential consistent with recent theoretical estimates. This direct evidence for a scalar potential on a macroscopic scale due to deterministically generated strain in graphene paves the way for engineering the optical and electronic properties of graphene and similar materials by using external strain.

Segmental Strain for Myocardial Scar Detection in Acute Infarcts and Follow-Up CMR Using Non-Contrast Cine Images

Aims Scar tissue from myocardial infarction is best visualized with cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE). Gadolinium-free alternatives for detection of myocardial scars are limited. This study investigated the feasibility of myocardial scar detection in acute infarcts and follow-up CMR using non-contrast cine images. Methods Fifty-seven patients with acute infarcts (15 female, mean age 61 ± 12 years, CMR 2.8 ± 2 days after infarction) were retrospectively evaluated with follow-up CMR exams available in thirty-two patients (9 female, 35 ± 14 days after infarction). Twenty-eight patients with normal CMR scans (2 female, mean age 47 ± 8 years) served as controls. Global and segmental strain parameters (global peak circumferential [GPCS], global peak longitudinal [GPLS], global peak radial strain [GPRS], segmental peak circumferential [SPCS], segmental peak longitudinal [SPLS], and segmental peak radial strain [SPRS]) were calculated from standard non-contrast balanced SSFP cine sequences using commercially available software (Segment CMR, Medviso, Sweden). Visual assessment of wall motion abnormalities on short axis cine images, as well as segmental circumferential strain calculations (endo-/epicardially contoured short axis cine and resulting polar plot strain map) of every patient (acute imaging and follow-up CMR) and control were presented for two blinded readers in random order, who were advised to localize potentially infarcted segments, blinded to LGE images and clinical information.Results While global strain values were impaired in patients with acute infarcts compared to controls (GPCS p= 0.01; GPLS p= 0.04; GPRS p= 0.01), global strain was similar between first CMR and follow-up imaging in the subgroup of 32 patients (GPCS p= 0.7; GPLS p=0.8; GPRS p=0.2). In acute infarcts and in follow-up CMR, patients had reduced mean SPCS in infarcted segments compared to remote myocardium (acute p= 0.03, follow-up exams p= 0.02). SPCS values in infarcted areas were similar in acute infarcts and in follow-up exams (p=0.8). In acute infarcts 74.6% of all in LGE infarcted segments (141/189) were correctly localized in polar plot strain maps compared to 44.4% (84/189) of infarcted segments detected by visual wall motion assessment only (p < 0.01). In follow-up exams, 81.5% of all in LGE infarcted segments (93/114 segments) were correctly localized in polar plot strain maps compared to 51.8% (59/114) of infarcted segments detected by visual wall motion assessment (p < 0.01).Conclusion Segmental circumferential strain derived from routinely acquired cine sequences detects nearly 75% acute infarcts and about 80% of infarcts in follow-up CMR and can potentially be used for scar identification based on non-contrast cine images, when gadolinium cant not be applied or LGE images are not available.

Segmental strain analysis for the detection of chronic ischemic scars in non-contrast cardiac MRI cine images

Cardiac magnetic resonance imaging (MRI) with late gadolinium enhancement (LGE) is considered the gold standard for scar detection after myocardial infarction. In times of increasing skepticism about gadolinium depositions in brain tissue and contraindications of gadolinium administration in some patient groups, tissue strain-based techniques for detecting ischemic scars should be further developed as part of clinical protocols. Therefore, the objective of the present work was to investigate whether segmental strain is noticeably affected in chronic infarcts and thus can be potentially used for infarct detection based on routinely acquired non-contrast cine images in patients with known coronary artery disease (CAD). Forty-six patients with known CAD and chronic scars in LGE images (5 female, mean age 52 ± 19 years) and 24 gender- and age-matched controls with normal cardiac MRI (2 female, mean age 47 ± 13 years) were retrospectively enrolled. Global (global peak circumferential [GPCS], global peak longitudinal [GPLS], global peak radial strain [GPRS]) and segmental (segmental peak circumferential [SPCS], segmental peak longitudinal [SPLS], segmental peak radial strain [SPRS]) strain parameters were calculated from standard non-contrast balanced SSFP cine sequences using commercially available software (Segment CMR, Medviso, Sweden). Visual wall motion assessment of short axis cine images as well as segmental circumferential strain calculations (endo-/epicardially contoured short axis cine and resulting polar plot strain map) of every patient and control were presented in random order to two independent blinded readers, which should localize potentially infarcted segments in those datasets blinded to LGE images and patient information. Global strain values were impaired in patients compared to controls (GPCS p = 0.02; GPLS p = 0.04; GPRS p = 0.01). Patients with preserved ejection fraction showed also impeded GPCS compared to healthy individuals (p = 0.04). In patients, mean SPCS was significantly impaired in subendocardially (− 5.4% ± 2) and in transmurally infarcted segments (− 1.2% ± 3) compared to remote myocardium (− 12.9% ± 3, p = 0.02 and 0.03, respectively). ROC analysis revealed an optimal cut-off value for SPCS for discriminating infarcted from remote myocardium of − 7.2% with a sensitivity of 89.4% and specificity of 85.7%. Mean SPRS was impeded in transmurally infarcted segments (15.9% ± 6) compared to SPRS of remote myocardium (31.4% ± 5; p = 0.02). The optimal cut-off value for SPRS for discriminating scar tissue from remote myocardium was 16.6% with a sensitivity of 83.3% and specificity of 76.5%. 80.3% of all in LGE infarcted segments (118/147) were correctly localized in segmental circumferential strain calculations based on non-contrast cine images compared to 53.7% (79/147) of infarcted segments detected by visual wall motion assessment (p > 0.01). Global strain parameters are impaired in patients with chronic infarcts compared to controls. Mean SPCS and SPRS in scar tissue is impeded compared to remote myocardium in infarcts patients. Blinded to LGE images, two readers correctly localized 80% of infarcted segments in segmental circumferential strain calculations based on non-contrast cine images, in contrast to only 54% of infarcted segments detected due to wall motion abnormalities in visual wall motion assessment. Analysis of segmental circumferential strain shows a promising method for detection of chronic scars in routinely acquired, non-contrast cine images for patients who cannot receive or decline gadolinium.