A Combined Experimental-Numerical Framework for Assessing the Load-Bearing Capacity of Existing PC Bridge Decks Accounting for Corrosion of Prestressing Strands.

Bridges constitute important elements of the transportation network. A vast part of the Italian existing infrastructural system dates to around 60 years ago, which implies that the related bridge structures were constructed according to past design guidelines and underwent a probable state of material deterioration (e.g., steel corrosion, concrete degradation), especially in those cases in which proper maintenance plans have not been periodically performed over the structural lifetime. Consequently, elaborating rapid yet effective safety assessment strategies for existing bridge structures represents a topical research line. This contribution presents a systematic experimental-numerical approach for assessing the load-bearing capacity of existing prestressed concrete (PC) bridge decks. This methodology is applied to the Longano PC viaduct (southern Italy) as a case study. Initially, natural frequencies and mode shapes of the bridge deck are experimentally identified from vibration data collected in situ through Operational Modal Analysis (OMA), based on which a numerical finite element (FE) model is developed and calibrated. In situ static load tests are then carried out to investigate the static deflections under maximum allowed serviceability loads, which are compared to values provided by the FE model for further validation. Since prestressing strands appear corroded in some portions of the main girders, numerical static nonlinear analysis with a concentrated plasticity approach is finally conducted to quantify the effects of various corrosion scenarios on the resulting load-bearing capacity of the bridge at ultimate limit states. The proposed methodology, encompassing both serviceability and ultimate conditions, can be used to identify critical parts of a large infrastructure network prior to performing widespread and expensive material test campaigns, to gain preliminary insight on the structural health of existing bridges and to plan a priority list of possible repairing actions in a reasonable, safe, and costly effective manner.

Early Impairment of Right Ventricular Morphology and Function in Transthyretin-Related Cardiac Amyloidosis.

BACKGROUND: Our study aimed to evaluate right ventricular (RV) morphology and strain (S) in the early stage of familial transthyretin (TTR) cardiac amyloidosis (CA). METHODS AND RESULTS: Thirty-seven patients with transthyretin mutation underwent 99mTc-3,3-diphosphono-1,2 propanodicarboxylic acid (99mTc-DPD) scans and/or cardiac magnetic resonance (CMR) to identify TTR CA. Each patient underwent echocardiography to quantify RV dimensions, tricuspid annular plane systolic excursion (TAPSE), systolic pulmonary artery pressure (sPAP), longitudinal (L) strain of the RV free wall, left ventricular (LV) septal thickness (ST), ejection fraction, E/E', LV global (G) L, radial (R), and circumferential (C) S. 99mTc-DPD and CMR revealed the accumulation in 22 of 37 patients (CA group) and no accumulation in 15 patients (no-CA group). Left ventricular (LV) septal thickness (ST) was higher (P < 0.0001) while LV ejection fraction and E/E' were lower (P < 0.05) in the CA group than the no-CA group. LV-global longitudinal strain (LS) was lower (P < 0.0001) in the CA-group than the no CA-group, whereas LV-global circumferential strain and LV-global radial strain were similar. The CA group showed higher values of RV dimensions (P < 0.05) and sPAP (0.02) and a lower (P = 0.002) TAPSE. Globally, RV-LS was lower (P = 0.005) in the CA group than the no-CA group. Basal and mid segments of the RV free wall showed a lower LS in the CA group than the no-CA group (P < 0.01), while apical S was similar between groups. CONCLUSIONS: RV deformation, particularly in basal and mid segments, is early impaired in CA.

Experimental Characterization of the FRCM-Concrete Interface Bond Behavior Assisted by Digital Image Correlation.

Digital Image Correlation (DIC) provides measurements without disturbing the specimen, which is a major advantage over contact methods. Additionally, DIC techniques provide full-field maps of response quantities like strains and displacements, unlike traditional methods that are limited to a local investigation. In this work, an experimental application of DIC is presented to investigate a problem of relevant interest in the civil engineering field, namely the interface behavior between externally bonded fabric reinforced cementitious mortar (FRCM) sheets and concrete substrate. This represents a widespread strengthening technique of existing reinforced concrete structures, but its effectiveness is strongly related to the bond behavior between composite fabric and underlying concrete. To investigate this phenomenon, a set of notched concrete beams are realized, reinforced with FRCM sheets on the bottom face, subsequently cured in different environmental conditions (humidity and temperature) and finally tested up to failure under three-point bending. Mechanical tests are carried out vis-à-vis DIC measurements using two distinct cameras simultaneously, one focused on the concrete front face and another focused on the FRCM-concrete interface. This experimental setup makes it possible to interpret the mechanical behavior and failure mode of the specimens not only from a traditional macroscopic viewpoint but also under a local perspective concerning the evolution of the strain distribution at the FRCM-concrete interface obtained by DIC in the pre- and postcracking phase.

Echocardiographic Findings in Cardiac Amyloidosis: Inside Two-Dimensional, Doppler, and Strain Imaging.

PURPOSE OF REVIEW: The aim is to provide a description of the most important echocardiographic features in systemic amyloidosis. RECENT FINDINGS: Amyloidosis is a heterogeneous group of multisystem disorders, characterized by an extracellular deposition of amyloid fibrils. Several imaging tests are available for the diagnosis; however, echocardiography is the cornerstone of the non-invasive imaging modality for cardiac amyloidosis. So far, little is known about the diagnosis of cardiac amyloidosis through imaging modalities. We summarized the most important echocardiographic findings in cardiac amyloidosis. Hence, we offered a systematic report of the diagnostic performance of cardiac amyloidosis using echocardiography.

Left ventricular endocardial longitudinal dysfunction persists after acute myocarditis with preserved ejection fraction.

BACKGROUND: The aim of present study was to assess left ventricular (LV) myocardial deformation and changes over time in patients with acute myocarditis (AM) with preserved ejection fraction detected by late gadolinium enhancement (LGE) magnetic resonance imaging. METHODS: Thirty-five male patients with AM diagnoses and preserved systolic function based on cardiac magnetic resonance imaging (MRI) were prospectively enrolled. On admission, echocardiography with measurements of global and segmental longitudinal (LS) strains was performed both at the endocardial (ENDO) and epicardial (EPI) levels. Findings were compared to 25 control subjects. Twenty-six patients were also monitored over a 22-month follow-up (FU group). RESULTS: On admission, global ENDO-LS was poorer in magnitude in AM (-19.2 ± 3.1) than in controls (-24.0 ± 1.05) (P < 0.0001), whereas EPI-LS was not different (-20.6 ± 3.4 vs -19.7 ± 6 P = NS). A functional increase in magnitude in both ENDO-LS (-20.8 ± 5.4, P = NS) and EPI-LS (-22.6 ± 4.6, P = 0.02) was found in FU vs AM patients. CONCLUSIONS: The present study demonstrates a steady ENDO-LS impairment in infarct-like AM during a 2-year follow-up period, despite a preserved LV ejection fraction.

Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors.

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data.

Images in cardiovascular medicine: caseous calcification of the mitral annulus.

A 78-year-old woman was admitted to our emergency department for subarachnoid hemorrhage. Since a month ago, she was taking warfarin after diagnosis, on transthoracic echocardiogram (TTE), of a suspected large atrial thrombus. The patient, referred to our institution for further investigation, presented asymptomatic; electrocardiogram showed sinus rhythm. TTE revealed an echo dense spherical mass located in the mitral periannular posterior region with moderate mitral regurgitation. Transesophageal echocardiography and cardiac computed tomography confirmed a calcified round mass (2.0 × 2.9 cm) with central areas of echolucency-like liquefaction surrounded by a hyperechogenic structure without systolic flow inside the cavity. The mass was diagnosed as caseous calcification of the mitral annulus (CCMA), a rare finding associated with a benign prognosis, requiring surgery only in the presence of mitral valve dysfunction. The diagnosis of CCMA is, often, misconstrued as thrombus, tumor, or abscess, leading to unnecessary investigations or interventions. Our patient was discharged after discontinuation of warfarin.

Endocardial and epicardial deformations in cardiac amyloidosis and hypertrophic cardiomyopathy.

BACKGROUND: The aim of the present study was to analyze epicardial (EPI) and endocardial (ENDO) strain (S) in patients with transthyretin-related cardiac amyloidosis (TTR-CA) and hypertrophic cardiomyopathy (HCM) using echocardiography (TTE) with 2-dimensional feature tracking imaging (FTI). METHODS AND RESULTS: Thirty-three subjects (11 with HCM, 11 with TTR-CA, and 11 healthy subjects as controls) with a New York Heart Association functional class ≤ II underwent conventional TTE and FTI. TTE was used for the evaluation of left ventricle (LV) wall thickness, mass, systolic and diastolic function. FTI was used for the evaluation of EPI and ENDO longitudinal, and circumferential, and radial S. LV wall thickness and mass were higher in both TTR-CA and HCM in comparison with controls (P < 0.001), but ejection fraction (EF) was similar among patients with TTR-CA, HCM and controls (63 ± 6%, 64 ± 6%, 61 ± 5%, respectively). ENDO and EPI longitudinal and circumferential S and radial S were significantly lower in HCM and TTR-CA when compared with controls (P < 0.01). No differences in EPI and ENDO longitudinal S, ENDO circumferential S and radial S were found between TTR-CA and HCM groups, while EPI circumferential S was significantly lower in the TTRCA group (6 ± 3.3%) than in the HCM group (8.1 ± 4.3%; P < 0.0001). CONCLUSIONS: Longitudinal, circumferential and radial LV deformations are impaired in patients with TTR-CA and HCM with a preserved EF. Impairment of EPI circumferential strain is greater in TTR-CA than in HCM.

Semiautomatic quantification of left ventricular function by two-dimensional feature tracking imaging echocardiography. A comparison study with cardiac magnetic resonance imaging.

OBJECTIVE: To evaluate the accuracy of a semiautomatic quantification of left ventricular (LV) volumes and ejection fraction (EF) using two-dimensional (2D) feature tracking imaging (FTI). METHODS: Thirty-four consecutive subjects (11 patients with dilated cardiomyopathy, 13 with hypertrophic cardiomyopathy, and 10 subjects with no cardiac disease) underwent, on the same day, trans-thoracic echocardiography (TTE) examination, FTI, and cardiac magnetic resonance imaging (MRI), as gold standard, in order to quantify LV volumes and EF. The echocardiographic quantification of LV volumes and EF was determined from four- and two-chamber views using both standard TTE Biplane Simpson's method and a semiautomatic border detection based on FTI. Furthermore, the time for data analysis for each method was measured. RESULTS: The time required for semiautomatic analysis of volumes and EF was significantly lower (P < 0.0001) by FTI (71 seconds) in comparison with standard biplane Simpson's method (93 seconds). LV volumes obtained by FTI were significant underestimated (P < 0.001) in comparison with MRI. Bland-Altman analysis of EDV and ESV using FTI and cardiac MRI showed a low level of agreement for EDV (mean difference = 40.8; SD = 39) and ESV (mean difference = 38.1; SD = 42). On the contrary, no significant difference between FTI and MRI in assessing the LVEF was found; furthermore, a very low bias (2 ± 12) by Bland-Altman analysis was found between FTI and cardiac MRI for the quantification of EF. CONCLUSION: Semiautomatic quantification of LV volumes using FTI allows an accurate, rapid, easy and reliable assessment of LV EF and a rough estimation of LV volumes.

Right ventricular outflow tract obstruction in hypertrophic cardiomyopathy.

Recently, new cardiac imaging techniques as cardiac magnetic resonance have shown to play a primary role for a recognition of unusual mechanisms of right and left ventricular obstruction. However, echocardiography remains the most widely used technique and the first step to recognize myocardial hypertrophy, blood flow velocity, and pressure gradients in real time (2). We describe a rare case of hypertrophic cardiomyopathy with isolated obstruction of right ventricular out flow where transthoracic echocardiography was able to detect right ventricular hypertrophy and obstruction.

Cerebral transient ischemic attack due to left ventricular thrombus formation in a young patient with silent myocardial infarction and normal coronary arteries.

Among many cardiac diseases related to cerebral stroke, left ventricular thrombus formation due to silent myocardial infarction with normal coronary arteries represents a rare cause of cerebral ischemia. We describe an unusual case of cerebral ischemia due to cardiac thrombus formation in a young patient with silent myocardial infarction and normal coronary arteries in which echocardiography and cardiac MR imaging clearly showed the embolic source.

Non compaction cardiomyopathy and Antiphospholipid syndrome: a catastrophic thromboembolic association.

We described a massive non compaction cardiomyopathy associated with Antiphospholipid syndrome in a 53-year-old male with many episodes of ischemic cerebral stroke complicated by functional disability, cognitive decline and vascular dementia. In our case, the association of massive non compaction cardiomyopathy and severe left ventricular dysfunction added to Antiphospholipid syndrome has showed a dramatic thromboembolic manifestation.

Lipomatous hypertrophy of the interatrial septum.

Lipomatous hypertrophy of the interatrial septum (LHIS) is a rare benign disorder that is characterized by accumulation and deposition of fat in the interatrial septum. Its etiology is still unknown, despite the theories that have been suggested. It usually occurs in older, obese people with a higher incidence in women. In most cases its diagnosis is made incidentally. Cardiac arrhythmias including atrial fibrillation, atrial premature contractions and atrioventricular block may occur as a consequence of involvement of the atrial wall and atrioventricular conduction pathways. We present a case of LHIS in an 87-year-old Italian woman.

Pharmacological washout for the correct evaluation of the head-up tilt testing.

Head-up tilt testing is an important tool in the diagnosis of syncope. Several different protocols are in use. We describe the case of a 70-year-old Italian woman admitted to our observation. The patient was in antihypertensive treatment with carvedilol and with a combination of lisinopril and hydrochlorothiazide. A simplified Italian protocol head-up tilt testing was performed. A 4.10 s pause with syncope and a profound hypotension (blood pressure values were 65/50 mm Hg) were observed after 3 min in the provocation phase. Second-degree atrioventricular Block of the 2:1 form, advanced second-degree atrioventricular block and junctional escape rhythm (28 bpm) were observed. A simplified Italian protocol head-up tilt testing was performed after 40 days of withdrawal of carvedilol. A 2 s pause with presyncope and a hypotension (blood pressure values were 80/70 mm Hg) were observed after 2 min in the provocation phase. ECG revealed a bradycardic sinusal rhythm with heart rate of 42 bpm. This case assesses the importance of a pharmacological washout for the correct evaluation of the head-up tilt testing.