Wall Strain Research Articles

Strain assessment of polyethylene pipes in dense sand subjected to axial displacement

Buried polyethylene pipes used in gas distribution systems can experience excessive wall strain when exposed to ground movement that can affect the performance of the pipes in service. This paper presents full-scale laboratory tests performed to investigate the responses of medium-density polyethylene (MDPE) gas-distribution pipes in dense sand when subjected to axial ground movement. Pipes buried in sand in a large test box were pulled at the rates of 0.5 mm/min, 1 mm/min, and 2 mm/min to simulate relative ground movement in the longitudinal direction. The test facility was instrumented to measure pulling force, pipe wall strain, and soil stress. The measured pullout force was significantly higher than predicted using the equations recommended in current design guidelines, which is attributed to the increase of normal stress on the pipe wall by shear-induced dilation of interface soil. The cavity expansion theory was successfully applied to calculate the normal stress increase. The distribution of measured strains was nonlinear along the pipe length. Assuming a parabolic distribution of the strains, simplified equations were developed to calculate pullout resistance and pipe wall strain from the relative ground displacement. The developed method reasonably predicted the pipe strain measured during the tests.

A Multimodality Imaging Approach to Defining Risk in Patients With Acute Pulmonary Embolism

Morbidity and mortality for acute pulmonary embolism (PE) remain high. Therapies such as catheter-directed thrombolysis may improve outcomes, but these are generally reserved for higher-risk patients. Imaging may help guide the use of the newer therapies, but current guidelines focus more on clinical factors. Our goal was to create a risk model that incorporated quantitative echocardiographic and computed tomography (CT) measures of right ventricular (RV) size and function, thrombus burden, and serum biomarkers of cardiac overload or injury. This was a retrospective study of 150 patients evaluated by a PE response team. Echocardiography was performed within 48hours of diagnosis. Computed tomography measures included RV/left ventricular (LV) ratio and thrombus load (Qanadli score). Echocardiography was used to obtain various quantitative measures of RV function. We compared characteristics of those who met the primary endpoint (7-day mortality and clinical deterioration) to those who did not. Receiver operating curve analysis was used to assess the performance of different combinations of clinically relevant features and the association with adverse outcomes. Fifty-two percent of patients were female, with age 62±17 years, systolic blood pressure 123±25mm Hg, heart rate 98±19, troponin 3.2±35ng/dL, and b-type natriuretic peptide (BNP) 467±653. Fourteen (9.3%) were treated with systemic thrombolytics, 27 (18%) underwent catheter-directed thrombolytics, 23 (15%) were intubated or required vasopressors, and 14 (9.3%) died. Patients who met the primary endpoint (44%) versus those who did not (56%) had lower RV S' (6.6 vs 11.9cm/sec; P<.001) and RV free wall strain (-10.9% vs -13.6%; P=.005), higher RV/LV ratio on CT, and higher serum BNP and troponin levels. Receiver operating curve analysis demonstrated an area under the curve of 0.89 for a model that included RV S', RV free wall strain and tricuspid annular plane systolic excursion/RV systolic pressure ratio from echo, thrombus load and RV/LV ratio from CT, and troponin and BNP levels. A combination of clinical, echo, and CT findings that reflect the hemodynamic effects of the embolism identified patients with adverse events related to acute PE. Optimized scoring systems that focus on reversible abnormalities attributable to PE may allow more appropriate triaging of intermediate- to high-risk patients with PE for early interventional strategy.

Right ventricular hypertrophy in apical hypertrophic cardiomyopathy.

Right ventricular hypertrophy (RVH+) in hypertrophic cardiomyopathy occurs in one third of patients, however, outcomes in apical hypertrophic cardiomyopathy (ApHCM) have not been described. We hypothesized that RVH+ in ApHCM is associated with more ventricular remodeling and dysfunction, and increased adverse events when compared with those without RVH (RVH-). Ninety-one ApHCM patients were retrospectively analyzed using 2D and speckle-tracking echocardiography (64±16 years old, 43% female). RVH+ was defined as wall thickness >5mm and was present in 23 (25%). Ventricular mechanics were characterized by global longitudinal strain (GLS), RV free wall strain, and myocardial work. New York Heart Association functional class>II, atrial fibrillation, and prior stroke were more prevalent in RVH+. Left ventricular (LV) size and ejection fraction were similar between groups, with greater septal (17vs. 14mm, p=.001) and apical (20vs. 18mm, p=.04) wall thickness in RVH+. When compared with RVH- patients, RVH+ had worse LV GLS (-8.6vs. -12.8%), global work index (820vs. 1172mmHg%) (both p<.001), and work efficiency (76vs. 83%, p=.001), as well as RV GLS (-14vs. -17.5%) and free wall strain (-17.3vs. -21.3%) (both p=.02). At 3-year follow-up RVH+ had greater incidence of heart failure hospitalization compared with RVH- (35vs. 7%, p=.003). RVH+ was associated with RV GLS (β =.2, p=.03), independent of clinical and echocardiographic variables. RVH+ patients with ApHCM have worse biventricular mechanics and myocardial work, and more heart failure hospitalization, as RVH- at mid-term follow-up.

The Association Between Angiographically Derived Radial Wall Strain and the Risk of Acute Myocardial Infarction

BackgroundThe radial wall strain (RWS) is a novel angiography-based method to assess the biomechanical property of the coronary artery and whether it can predict future acute myocardial infarction (AMI) events remains to be elucidated. ObjectivesThis study aimed to investigate the association between angiography-derived RWS and future AMI events in mild to intermediate lesions. MethodsWe performed a matched case-control analysis nested in a retrospective cohort of patients who had received prior angiography (the index procedure) at least 1 month before and were hospitalized again for repeat angiography. Patients with at least 1 de novo mild to intermediate lesion identified at the index procedure and eligible for RWS analysis were enrolled. The study identified cases with target lesion–related AMI diagnosed at the repeat angiography, matching each case to 3 control subjects without AMI. ResultsAltogether 44 patients with lesion-related AMI and 132 matched controls were enrolled. The median diameter stenosis of the overall interrogated lesions was 34.0%. The baseline maximum RWS (RWSmax), which was defined as the highest RWS in the stenotic segment, was significantly higher in lesions responsible for AMI than those that remained quiescent (median 13% vs 10%; P < 0.001). RWSmax was predictive of lesion-related AMI, with an area under the curve of 0.83 (95% CI: 0.76-0.90; P < 0.001) and an optimal cutoff >12%. RWSmax >12% was found to be independently associated with subsequent AMI events with a risk ratio of 7.25 (95% CI: 3.94-13.37; P < 0.001). ConclusionsAmong angiographically mild to intermediate lesions, a high-strain pattern identified by angiography-derived RWS was associated with an increased risk of AMI events.

Recovery of Biventricular Function After Catheter Intervention or Surgery for Neonatal Coarctation of the Aorta

BackgroundCritical coarctation of the aorta (CoA) is a life-threatening condition in newborns that is associated with biventricular dysfunction. ObjectivesThe purpose of this study was to examine clinical outcome and echocardiographic changes in isthmus diameter and biventricular function in newborns with critical CoA treated with balloon dilation/stent placement or surgery. MethodsThis is a retrospective single-center cohort study of 26 consecutive neonates with isolated critical CoA, who underwent transcatheter intervention (balloon angioplasty/stent; n = 10) or surgical CoA-repair (n = 16) (2012-2021). Isthmus dimensions and biventricular function at baseline and at hospital discharge were examined by echocardiography, including strain analysis of systolic and diastolic function using 2-dimensional speckle tracking. ResultsCardiogenic shock at hospital admission was more frequent in the interventional vs the surgical cohort (50% vs 25% of neonates). Echocardiographic isthmus diameter increased with therapy by 0.9 ± 0.1 mm and 1.0 ± 0.1 mm, respectively. Severe systolic left ventricular (LV) dysfunction was more common in interventional patients pre-therapy (LV ejection fraction <50% in 90% vs 38% of surgical patients), resulting in strongly reduced longitudinal strain (LV: −12.3% vs −16.3%; right ventricle:−13.8% vs −16.1% in the interventional and surgical patients, respectively). Prior to hospital discharge, all 26 patients had full recovery of biventricular systolic function, including normalization of longitudinal, radial, and circumferential LV strain and longitudinal right ventricular free wall strain. Improvement of LV diastolic function by strain analysis was evident in both cohorts pre-hospital discharge. ConclusionsInitial treatment of isolated CoA by percutaneous transcatheter intervention or surgical repair results in recovery of biventricular systolic function, making transcatheter treatment particularly suitable as rescue therapy for neonates with critical CoA.

Reduced inferior wall longitudinal strain is associated with malignant arrhythmias in non-ischemic heart failure.

Reduced systolic myocardial function in the inferior region of the left ventricle has been suggested to be associated with malignant arrhythmias. We tested this hypothesis in patients with non-ischemic heart failure. Patients with non-ischemic heart failure (left ventricular ejection fraction [LVEF]<35%) were evaluated by 2D-speckle-tracking echocardiography. The regional longitudinal strain was calculated for each of the six left ventricular walls. The reduced regional function was defined as strain below the median. The outcome was a composite of sudden cardiac death, admission with sustained ventricular arrhythmia, resuscitated cardiac arrest, and appropriate therapy from a primary prophylactic implantable cardioverter defibrillator. Time-to-first-event analysis was performed using a Cox model. From two centers, 401 patients were included (median age: 63 years, 72% male) with a median LVEF of 25% (interquartile range [IQR] 20;30), and a median inferior wall strain of -9.0% (-12.5; -5.4). During a median follow-up of 4.0 years, 52 outcomes occurred. After multivariate adjustment for clinical and electrocardiographic parameters, inferior wall strain was independently associated with the outcome (HR 2.50 [1.35; 4.62], p=.003). No independent association was found between the composite outcome and reduced strain in any of the other left ventricular walls, Global Longitudinal Strain (HR 1.66 [0.93; 2.98], p=.09), or LVEF (HR 1.33 [0.75; 2.33], p=.33). Below median strain in the left ventricular inferior region was independently associated with a 2.5-fold increase in the risk of malignant arrhythmias and sudden cardiac death in patients with non-ischemic heart failure.

Subclinical Myocardial Injury in Patients Recovered from COVID-19 Pneumonia: Predictors and Longitudinal Assessment

(1) Background: Emerging data regarding patients recovered from COVID-19 are reported in the literature, but cardiac sequelae have not yet been clarified. To quickly detect any cardiac involvement at follow-up, the aims of the research were to identify: elements at admission predisposing subclinical myocardial injury at follow up; the relationship between subclinical myocardial injury and multiparametric evaluation at follow-up; and subclinical myocardial injury longitudinal evolution. (2) Methods and Results: A total of 229 consecutive patients hospitalised for moderate to severe COVID-19 pneumonia were initially enrolled, of which 225 were available for follow-up. All patients underwent a first follow-up visit, which included a clinical evaluation, a laboratory test, echocardiography, a six-minute walking test (6MWT), and a pulmonary functional test. Of the 225 patients, 43 (19%) underwent a second follow-up visit. The median time to the first follow-up after discharge was 5 months, and the median time to the second follow-up after discharge was 12 months. Left ventricular global longitudinal strain (LVGLS) and right ventricular free wall strain (RVFWS) were reduced in 36% (n = 81) and 7.2% (n = 16) of the patients, respectively, at first the follow-up visit. LVGLS impairment showed correlations with patients of male gender (p 0.008, OR 2.32 (95% CI 1.24-4.42)), the presence of at least one cardiovascular risk factor (p < 0.001, OR 6.44 (95% CI 3.07-14.9)), and final oxygen saturation (p 0.002, OR 0.99 (95% CI 0.98-1)) for the 6MWTs. Subclinical myocardial dysfunction had not significantly improved at the 12-month follow-ups. (3) Conclusions: in patients recovered from COVID-19 pneumonia, left ventricular subclinical myocardial injury was related to cardiovascular risk factors and appeared stable during follow-up.

Treprostinil in Neonates with Congenital Diaphragmatic Hernia-Related Pulmonary Hypertension

To describe our experience with treprostinil, evaluate correlations with cardiac function, and assess for adverse effects in neonates with congenital diaphragmatic hernia-related pulmonary hypertension (CDH-PH). A retrospective review of a single-center prospective registry at a quaternary care children's hospital. Patients included in the study had CDH-PH treated with treprostinil between April 2013 and September 2021. Assessed outcomes were brain-type natriuretic peptide levels and quantitative echocardiographic parameters collected at baseline, 1week, 2weeks, and 1month after treprostinil initiation. Right ventricular (RV) function was assessed by tricuspid annular plane systolic excursion Z-score and speckle tracking echocardiography (global longitudinal and free wall strain). Septal position and left ventricular (LV) compression were assessed by eccentricity index and M-mode Z-scores. Fifty-one patients were included, with an average expected/observed lung-to-head ratio of 28.4±9.0%. Most patients required extra-corporeal membrane oxygenation (n=45, 88%). Survival to hospital discharge was 31/49 (63%). Treprostinil was initiated at a median age of 19days with a median effective dose of 34ng/kg/minute. Median baseline brain-type natriuretic peptide level decreased from 416.9 pg/mL to 120.5 pg/mL after 1month. Treprostinil was associated with improved tricuspid annular plane systolic excursion Z-score, RV global longitudinal strain, RV free wall strain, LV eccentricity index, and LV diastolic and systolic dimensions, reflecting less compression by the RV, regardless of ultimate patient survival. No serious adverse effects were recorded. In neonates with CDH-PH, treprostinil administration is well tolerated and is associated with improved RV size and function.

The use of 2-D speckle tracking echocardiography in differentiating healthy adolescent athletes with right ventricular outflow tract dilation from patients with arrhythmogenic cardiomyopathy

AimsEchocardiographic assessment of adolescent athletes for arrhythmogenic cardiomyopathy (ACM) can be challenging owing to right ventricular (RV) exercise-related remodelling, particularly RV outflow tract (RVOT) dilation. The aim of this study is to evaluate the role of RV 2-D speckle tracking echocardiography (STE) in comparing healthy adolescent athletes with and without RVOT dilation to patients with ACM. Methods and resultsA total of 391 adolescent athletes, mean age 14.5 ± 1.7 years, evaluated at three sports academies between 2014 and 2019 were included, and compared to previously reported ACM patients (n = 38 definite and n = 39 borderline). Peak systolic RV free wall (RVFW-Sl), global and segmental strain (Sl), and corresponding strain rates (SRl) were calculated. The participants meeting the major modified Task Force Criteria (mTFC) for RVOT dilation were defined as mTFC+ (n = 58, 14.8%), and the rest as mTFC- (n = 333, 85.2%). Mean RVFW-Sl was −27.6 ± 3.4% overall, −28.2 ± 4.1% in the mTFC+ group and − 27.5 ± 3.3% in the mTFC- group. mTFC+ athletes had normal RV-FW-Sl when compared to definite (−29% vs −19%, p < 0.001) and borderline ACM (−29% vs −21%, p < 0.001) cohorts. In addition, all mean global and regional Sl and SRl values were no worse in the mTFC+ group compared to the mTFC- (p values range < 0.0001 to 0.1, inferiority margin of 2% and 0.1 s−1 respectively). ConclusionsIn athletes with RVOT dilation meeting the major mTFC, STE evaluation of the RV can demostrate normal function and differentiate physiological remodelling from pathological changes found in ACM, improving screening in grey-area cases.

Mysterious right ventricular function detection in isolated left anterior descending disease by speckle tracking imaging

Background and aimEarly detection of impaired right ventricle (RV) would give significant data for management strategy and prognosis in patients with history of cardiac disease. Echocardiography machine is still the first and most widely used cardiac imaging modality in diagnosing heart disease and assessing systolic and diastolic function with high accuracy. The study aimed to assess mysterious RV function in significant isolated left anterior descending (LAD) disease by imaging with speckle tracking, strain, and strain rate.Patients and methodsThe present study was a comparative prospective study included 100 participants, 50 patients with significant LAD disease who were candidates for Percutaneous coronary intervention (PCI) (group I), and 50 persons as a control group (group II). All participants were exposed to full medical history, clinical examination, ECG, conventional echo, tissue Doppler, speckle tracking imaging.ResultsGlobal longitudinal free wall strain was statistically lower in patient than control group (−19.21±4.11 in patient group vs. −23.73±1.53 in control group,P&lt;0.001), and RV peak systolic strain rate was reduced in patient group than control group (−1.47±0.55 vs. −1.87±0.42,P&lt;0.001).ConclusionIn isolated significant LAD disease RV function should be assessed even after opening of LAD by PCI. New echo modality like strain and strain rate are useful echo methods to detect mysterious RV function in patients with significant LAD disease.

Prognostic Value of Right Ventricular Dysfunction in Patients With Decompensated Chronic Heart Failure

Aim To determine the incidence rate and the practical significance of right ventricular dysfunction (RVD) in the development of cardiovascular complications in patients with decompensated chronic heart failure (DCHF).Material and methods This prospective, single-site observational study included 171 patients older than 18 years with NYHA functional class (FC) II-IV chronic heart failure (CHF) who were hospitalized for DCHF. Standard and extended 2D and 3D echocardiography (EchoCG) was performed for all patients on admission. Additionally, functional characteristics of the right ventricle (RV) were evaluated in the 3D mode followed by autonomic 3D processing with a EchoPac station (USA). RVD was taken as a disorder of two or more RV functional parameters according to results of 2D EchoCG, or a reduced RV free wall strain according to results of 2D speckle-tracking EchoCG, or a reduced RV ejection fraction (EF) according to results of 3D EchoCG. Statistical analysis was performed with a SPSS Statistics v. 26.0 software.Results The incidence rate of RVD in general population of patients with DCHF was 75.4 % (n=129). A higher prevalence of RVD was observed in patients with CHF with a low left ventricular (LV) EF (90.1 %). Patients with RVD had a more severe clinical status (significantly higher FC and higher Clinical Condition Scale (CCS) scores), more frequent atrial fibrillation (AF), and higher concentrations of uric acid and total bilirubin. RVD significantly correlated with male sex (odds ratio (OR), 2.05; 95 % confidence interval (CI), 1.01–4.19; р=0.046) and AF (OR, 3.52; 95 % CI, 1.71–7.26; р&lt;0.001). Patients with RVD had lower values of both LV and RV function. Lower LV EF and AF increased the probability of RVD by 1.06 times (95 % CI, 0.90–0.98; р=0.001) and by 2.63 times (95 % CI, 1.08–6.40; р=0.001), respectively. Evaluation of the predictive significance of RV parameters measured by 2D and 3D EchoCG showed only effects of RV EF (2D) and RV global longitudinal strain (GLS) (3D) on all-cause hospitalization. RVD as evaluated by accepted criteria did not influence adverse outcomes.Conclusion The determined incidence, correlations, and the predictive value of RVD in patients with DCHF indicated the appropriateness of assessing the RV function to optimize the management of patients regardless of the CHF phenotype.

Thymidine Phosphorylase Deficiency or Inhibition Preserves Cardiac Function in Mice With Acute Myocardial Infarction.

Background Ischemic cardiovascular disease is the leading cause of death worldwide. Current pharmacologic therapy has multiple limitations, and patients remain symptomatic despite maximal medical therapies. Deficiency or inhibition of thymidine phosphorylase (TYMP) in mice reduces thrombosis, suggesting that TYMP could be a novel therapeutic target for patients with acute myocardial infarction (AMI). Methods and Results A mouse AMI model was established by ligation of the left anterior descending coronary artery in C57BL/6J wild-type and TYMP-deficient (Tymp-/-) mice. Cardiac function was monitored by echocardiography or Langendorff assay. TYMP-deficient hearts had lower baseline contractility. However, cardiac function, systolic left ventricle anterior wall thickness, and diastolic wall strain were significantly greater 4 weeks after AMI compared with wild-type hearts. TYMP deficiency reduced microthrombus formation after AMI. TYMP deficiency did not affect angiogenesis in either normal or infarcted myocardium but increased arteriogenesis post-AMI. TYMP deficiency enhanced the mobilization of bone marrow stem cells and promoted mesenchymal stem cell (MSC) proliferation, migration, and resistance to inflammation and hypoxia. TYMP deficiency increased the number of larger MSCs and decreased matrix metalloproteinase-2 expression, resulting in a high homing capability. TYMP deficiency induced constitutive AKT phosphorylation in MSCs but reduced expression of genes associated with retinoid-interferon-induced mortality-19, a molecule that enhances cell death. Inhibition of TYMP with its selective inhibitor, tipiracil, phenocopied TYMP deficiency, improved post-AMI cardiac function and systolic left ventricle anterior wall thickness, attenuated diastolic stiffness, and reduced infarct size. Conclusions This study demonstrated that TYMP plays an adverse role after AMI. Targeting TYMP may be a novel therapy for patients with AMI.

Disturbances of the ascending aorta biomechanics in moderate dilatation and aneurysm

Aim. To compare disturbances of the ascending aorta (AA) biomechanics in pa­­tients with moderate dilatation and aneurysm using segmental aortic strain ultrasound.Material and methods. Fifteen patients with moderate AA dilatation (40-49 mm), 17 patients with AA aneurysm (≥50 mm) and 11 healthy volunteers (AA&lt;40 mm) were examined using 2D multiplane transesophageal echocardiography (TEE). The entire thoracic aorta (TA) was assessed. Using 2D speckle-tracking TEE, global peak systolic circumferential strain (GCS, %), global peak systolic circumferential strain normalized to pulse pressure (GCS/PP) and aortic stiffness (β2) index at 4 TA levels (sinuses of Valsalva, sinotubular junction, mid-ascending aorta, descending aorta) were calculated.Results. In healthy volunteers with TA diameter of 26,6 mm (25,2; 28,4) unidi­rec­tional uniform GCS of 9,7% (8,4; 11,7), GCS/PP of 18,4 (14,9; 2,.6) and uniform aortic stiffness (β2) 5,9 (4,8; 6,7) in all TA segments were revealed. There was a pro­portionally significant decrease in deformation parameters up to negative values and an increase of the ascending aortic wall stiffness from the aortic annulus to the descending aorta with a maximum in the highest dilatation zone in patients with moderate dilatation and aneurysm. Moreover, in these patients aortic wall strain and stiffness did not differ in all TA segments (p&gt;0,05). The AA diameter in maximum dilatation zone in patients with aneurysm was significantly higher than in patients with moderate dilatation — 52 mm (51; 55) versus 47 mm (45; 48), p&lt;0,001, respectively. An inverse correlation between the AA diameter in maximum dilatation zone and aortic strain (GCS: r=-0,61; p&lt;0.001 and GCS/PP: r=-0,62; p&lt;0,001) and a direct correlation with the aortic stiffness (β2) index (r=0,56; p&lt;0,05) were revealed.Conclusion. Assessment of the aortic biomechanics along with the AA diameter has an independent diagnostic value when choosing an individual surgical strategy in patients with moderate dilatation and AA aneurysm.

Angiography-Based Superficial Wall Strain of De Novo Stenotic Coronary Arteries: Serial Assessment of Vessels Treated with Bioresorbable Scaffold or Drug-Eluting Stent

ObjectivesThis study sought to present an angiography-based computational model for serial assessment of superficial wall strain (SWS, dimensionless) of de-novo coronary stenoses treated with either bioresorbable scaffold (BRS) or drug-eluting stent (DES). BackgroundA novel method for SWS allows the assessment of the mechanical status of arteries in-vivo, which may help for predicting cardiovascular outcomes. MethodsPatients with arterial stenosis treated with BRS (n = 21) or DES (n = 21) were included from ABSORB Cohort B1 and AIDA trials. The SWS analyses were performed along with quantitative coronary angiography (QCA) at pre-PCI, post-PCI, and 5-year follow-up. Measurements of QCA and SWS parameters were quantified at the treated segment and adjacent 5-mm proximal and distal edges. ResultsBefore PCI, the peak SWS on the ‘to be treated’ segment (0.79 ± 0.36) was significantly higher than at both virtual edges (0.44 ± 0.14 and 0.45 ± 0.21; both p < 0.001). The peak SWS in the treated segment significantly decreased by 0.44 ± 0.13 (p < 0.001). The surface area of high SWS decreased from 69.97mm2 to 40.08mm2 (p = 0.002). The peak SWS in BRS group decreased to a similar extent (p = 0.775) from 0.81 ± 0.36 to 0.41 ± 0.14 (p < 0.001), compared with DES group from 0.77 ± 0.39 to 0.47 ± 0.13 (p = 0.001). Relocation of high SWS to device edges was often observed in both groups after PCI (35 of 82 cases, 41.7 %). At follow-up of BRS, the peak SWS remained unchanged compared to post-PCI (0.40 ± 0.12 versus 0.36 ± 0.09, p = 0.319). ConclusionAngiography-based SWS provided valuable information about the mechanical status of coronary arteries. Device implantation led to a significant decrease of SWS to a similar extent with either polymer-based scaffolds or permanent metallic stents.

Lateral ground movement effects near a joint of MDPE gas distribution pipes

Buried medium-density polyethylene (MDPE) pipes are widely used for gas distribution systems in Canada and worldwide. When exposed to geotechnical hazards such as ground movements, these pipes can experience excessive distresses, leading to leaking or failure. This research investigates the effects of ground movement near a tee connection of MDPE gas distribution pipes. If the ground movement is parallel to a branch, the branch pipe experiences an axial force, and the main pipe experiences bending deformation/strains. The axial forces and the wall strains were investigated in this study using full-scale laboratory tests. Test results showed that the axial force on the branch and strains on the main pipe depend on the burial depth, backfill soil density, and the pipe diameter due to the effects on the shearing resistance of the soil. The soil shearing resistance was less for shallow buried pipes, resulting in a lower axial force in the branch but higher bending strain in the main pipe. The axial pullout resistance of the main pipe also contributed to the wall strains of this laterally loaded pipe at large displacements. The conventional beam-on-elastic foundation solution reasonably estimated the pipe wall strains within the linear range of deformations. Nonlinear analyses, including lateral and axial soil springs, are recommended to capture the nonlinear responses at large displacements.

Cardiac Mechanics and Kidney Function Decline in the Cardiovascular Health Study.

Clinical heart failure frequently coexists with chronic kidney disease (CKD) and may precipitate kidney function decline. However, whether earlier-stage myocardial dysfunction assessable by speckle tracking echocardiography is a contributor to kidney function decline remains unknown. We studied 2135 Cardiovascular Health Study (CHS) participants who were free of clinical heart failure and had Year 2-baseline 2D speckle tracking echocardiography and two measurements of estimated glomerular filtration rate (eGFR) (Year 2 and Year 9). "Archival" speckle tracking of digitized echocardiogram videotapes was utilized to measure left ventricular longitudinal strain (LVLS), LV early diastolic strain rate (EDSR), left atrial reservoir strain (LARS), right ventricular free wall strain (RVFWS), and mitral annular velocity (e'). Multivariable Poisson regression models that adjusted for demographics and cardiovascular risk factors were used to investigate the independent associations of cardiac mechanics indices and decline in kidney function defined as a 30% decline in eGFR over 7 years. In risk factor (RF) models LVLS, EDSR, RVFWS, and e' were all significantly associated with the prevalence of kidney disease. After multivariable adjustment, left atrial dysfunction (RR 1.18 [95% CI 1.01, 1.38] per SD lower LARS] and left ventricular diastolic dysfunction (RR 1.21 [95% CI 1.04, 1.41] per SD lower EDSR) were each significantly associated with 30% decline in eGFR. Subclinical myocardial dysfunction suggesting abnormal diastolic function detected by 2D speckle-tracking echocardiography was independently associated with decline in kidney function over time. Further studies are needed to understand the mechanisms of these associations and to test whether interventions that may improve subclinical myocardial dysfunction can prevent decline of kidney function.

Biventricular Function is Impaired in Right Ventricular Septal Pacing-A Prospective Study Using Myocardial Strain Imaging.

Left ventricular (LV) dysfunction is known to occur after right ventricular (RV) pacing; the effect on RV function is less well studied. The aim of this study was to assess the impact of RV mid-septal pacing upon RV function using the novel parameters of speckle-tracking derived RV global longitudinal strain (RV GLS) and RV free wall strain (RV FWS), as well as the conventional parameters RV fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), and tricuspid annular systolic velocity (RV S'). Thirty-two (32) consecutive patients with normal baseline LV and RV function requiring permanent pacemaker insertion were prospectively recruited. Echocardiography was performed prior to implantation, at 1 day, 1 month and 1 year after implantation, with 29 patients completing follow-up. After 1 year, three patients (10%) with otherwise normal RV parameters developed abnormal RV strain patterns. Compared to 1 day after implantation, at 1 year significant reductions were observed in mean RV GLS (-24.8 to -21.8%) RV S' (15.1 to 12.2 cm/s), TAPSE (24.2 to 21.9 mm), RV GLS (-24.8 to -21.8%), left ventricular ejection fraction (LVEF) (66.0 to 57.9%), LV GLS (-19.9 to 17.0), all p<0.01. There was a non-significant reduction for RV FWS (-29.0 to -26.7%, p=0.06) and there was no change in RV FAC (49.1 to 46.9%, p=0.24). We report abnormalities of RV strain developing 1 year after pacemaker insertion. Measurement of myocardial strain is emerging as an additional method to detect patients at risk of RV dysfunction in those who have undergone pacemaker implantation.

Radial Wall Strain Assessment From AI-Assisted Angiography: Feasibility and Agreement With OCT as Reference Standard.

High-strain spots in coronary arteries are associated with plaque vulnerability and predict future events. Artificial intelligence currently enables the calculation of radial wall strain (RWS) from coronary angiography (RWSAngio). This study aimed to determine the agreement between novel RWSAngio and RWS derived from optical coherence tomography (OCT) followed by finite element analysis, as the established reference standard (RWSOCT). All lesions from a previous OCT study were enrolled. OCT was automatically coregistered with angiography. RWSAngio was computed as the relative luminal deformation throughout the cardiac cycle, whereas RWSOCT was analyzed using finite element analysis on OCT cross-sections at 1-mm intervals. The luminal deformation in the direction of minimal lumen diameter was used to derive RWSOCT, using the same definition as RWSAngio. The maximal RWSOCT and RWSAngio at healthy segments adjacent to the interrogated lesion were also analyzed. Finite element analysis was performed in 578 OCT cross-sections from 45 lesions stemming from 36 patients. RWSAngio showed good correlation and agreement with RWSOCT (r = 0.91; P < .001; Lin coefficient = 0.85). RWSAngio in atherosclerotic segments was significantly higher than that in healthy segments (12.6% [11.0, 16.0] vs 4.5% [2.9, 5.5], P < .001). The intraclass correlation coefficients for intra- and interobserver variability in repeated RWSAngio analysis were 0.92 (95% CI, 0.87-0.95) and 0.88 (95% CI, 0.81-0.92), respectively. The mean analysis time of RWSOCT and RWSAngio for each lesion was 95.0 ± 41.1 and 0.9 ± 0.1 minutes, respectively. Radial wall strain from coronary angiography can be rapidly and easily computed solely from angiography, showing excellent agreement with strain derived from coregistered OCT. This novel and simple method might provide a cost-effective biomechanical assessment in large populations.

Speckle Tracking Analysis in Fetuses with D-Transposition: Predicting the Need for Urgent Neonatal Balloon Atrial Septostomy.

Speckle tracking analysis of the endocardium of the right (RV) and left (LV) ventricles was used to evaluate the size, shape, and contractility of these chambers in fetuses with D-Transposition of the great arteries (D-TGA) to identify fetuses that would require emergent balloon atrial septostomy (BAS) after birth. This was a retrospective analysis of fetuses with D-TGA and intact ventricular septum that were divided into 2 groups. Group 1 underwent urgent BAS after birth because of a restrictive atrial septum and group 2 did not. Using speckle tracking analysis, the end-diastolic and end-systolic RV and LV areas, lengths, widths, sphericity indices, and contractility were computed. Logistic regression analysis was performed to identify fetuses who would require urgent neonatal BAS. Of the 39 fetuses with D-TGA, 55% (n = 22) required urgent neonatal BAS (group 1) and 45% (n = 17) (group 2) did not. When comparing D-TGA groups 1 and 2, differences were seen in RV and LV area, sphericity index for segment 1 of the LV, LV fractional area of change and free wall annular plane systolic excursion, fractional shortening for LV segment 12, and RV free wall strain. Regression analysis of these measurements identified 91% of neonates who underwent BAS, with a false-positive rate of 12%. Using speckle tracking analysis to evaluate the RV and LV, measurable differences were identified for the RV and LV size, shape, and contractility between fetuses who underwent neonatal urgent BAS vs. those who did not require this procedure.

Right ventricular function assessment by 3D echocardiography and 2D speckle-tracking imaging in acute pulmonary embolism

Objective: To assess changes in right ventricular (RV) function parameters determined by three-dimensional (3D) echocardiography and two-dimensional (2D) speckle-tracking echocardiography in patients with acute pulmonary embolism without systemic hypotension, as compare to a control population. Subject and method: Fifty-seven intermediate-high risk pulmonary embolism patients were prospectively studied at the onset of the acute episode and after median follow-up periods of 30 days. A control group of age-and sex-matched subjects were selected. All patients and the controls underwent 2D and 3D transthoracic echocardiography within 24 hours of pulmonary embolism diagnosis and one month after hospital discharge. Tricuspid annular peak systolic velocity (s’), tricuspid annular plane systolic excursion (TAPSE), RV diameter, RV fractional area change (FAC), 3D RV ejection fraction (EF), 2D RV global strain and RV free wall strain were measured. Result: From Dec. 2019 to March 2022, fifty-seven patients with acute intermediate-high risk of early mortality PE were included. Mean age was 56 ± 14 years. Men accounted for 47.4% (27/57). Control group consisted of 34 subjects. Pulmonary embolism patients initially had RV dysfunction as assessed by 2D and 3D parameters: RV diameter: 29.3 ± 4.6mm; TAPSE: 14.6 (9.1-15.7) mm; FAC: 31.5 (30.5-39.9)%; 3DRVEFL 31.9 ± 7.7%; RVGS: -9.8 ± 3%, RVFWS: -8.9 ± 3.3%. At 30-day follow-up: s’, TAPSE, RV diameter, RV FAC were restored compared to the control group, systolic pulmonary artery pressures decreased significantly, right atrial pressure, also decreased significantly at follow-up, contrary to 3DRVEF and RV 2D global strain and free wall strain. Conclusion: After 1 month of anticoagulant therapy in patients with intermediate-high risk pulmonary embolism, RV function has not fully recovered as assessed by 3D RVEF and 2D strain imaging, while the traditional echocardiographic assessment could not detect this incomplete recovery. Further studies are needed to assess the prognostic role and implications of this residual 3DRVEF and 2D RV strain impairment after PE.