Echocardiographic scores for biventricular repair risk prediction of congenital heart disease with borderline left ventricle: a review.

The aim of this review is to highlight the strengths and limitations of major echocardiographic biventricular repair (BVR) prediction models for borderline left ventricle (LV) in complex congenital heart disease (CHD). A systematic search in the National Library of Medicine for Medical Subject Headings and free text terms including echocardiography, CHD, and scores, was performed. The search was refined by adding keywords for critical aortic stenosis (AS), borderline LV, complex left ventricular outflow tract (LVOT) obstruction, hypoplastic left heart syndrome/complex (HLHS/HLHC), and unbalanced atrio-ventricular septal defects (uAVSD). Fifteen studies were selected for the final analysis. We outlined what echocardiographic scores for different types of complex CHD with diminutive LV are available. Scores for CHD with LVOT obstruction including critical AS, HLHS/HLHC, and aortic arch hypoplasia have been validated and implemented by several studies. Scores for uAVSD with right ventricle (RV) dominance have also been established and implemented, the first being the atrioventricular valve index (AVVI). In addition to AVII, both LV/RV inflow angle and LV inflow index have all been validated for the prediction of BVR. We conclude with a discussion of limitations in the development and validation of each of these scores, including retrospective design during score development, heterogeneity in echocardiographic parameters evaluated, variability in the definition of outcomes, differences in adopted surgical and Interventional strategies, and institutional differences. Furthermore, scores developed in the past two decades may have little clinical relevance now. In summary, we provide a review of echocardiographic scores for BVR in complex CHD with a diminutive LV that may serve as a guide for use in modern clinical practice.

Planning Transition of Care for Adolescents Affected by Congenital Heart Disease: The Irish National Pathway.

At some point in their life, adolescent patients with a congenital heart disease (CHD) transition from paediatric services to adult care facilities. The process is not without any risks, as it is often linked with a significantly progressive deterioration in adolescents' health and loss of follow-up. In fact, transition patients often encounter troubles in finding a care giver who is comfortable managing their condition, or in re-establishing trust with the new care provider. Planning the rules of transition is pivotal in preventing these risks. Unfortunately, the American and European guidelines on CHD provide just generic statements about transition. In a recently published worldwide inter-societies consensus document, a hybrid model of transition, which should be adapted for use in high- and low- resource settings, has been suggested. Currently, in literature there are a few models of transition for CHD patients, but they are by far local models and cannot be generalized to other regions or countries. This paper describes the Irish model for transition of care of CHD patients. Due to the peculiarity of the healthcare organization in the Republic of Ireland, which is centralized with one main referral centre for paediatric cardiology (in Dublin, with a few smaller satellite centres all around, according to the "hub and spoke" model) and one centre for adult with CHD (in Dublin), the model can be considered as a national one and the first to be released in the old continent.

Acute Cardiovascular Manifestations in 286 Children With Multisystem Inflammatory Syndrome Associated With COVID-19 Infection in Europe.

BACKGROUND: The aim of the study was to document cardiovascular clinical findings, cardiac imaging, and laboratory markers in children presenting with the novel multisystem inflammatory syndrome associated with coronavirus disease 2019 (COVID-19) infection. METHODS: This real-time internet-based survey has been endorsed by the Association for European Paediatric and Congenital Cardiologists Working Groups for Cardiac Imaging and Cardiovascular Intensive Care. Children 0 to 18 years of age admitted to a hospital between February 1 and June 6, 2020, with a diagnosis of an inflammatory syndrome and acute cardiovascular complications were included. RESULTS: A total of 286 children from 55 centers in 17 European countries were included. The median age was 8.4 years (interquartile range, 3.8-12.4 years) and 67% were boys. The most common cardiovascular complications were shock, cardiac arrhythmias, pericardial effusion, and coronary artery dilatation. Reduced left ventricular ejection fraction was present in over half of the patients, and a vast majority of children had raised cardiac troponin when checked. The biochemical markers of inflammation were raised in most patients on admission: elevated C-reactive protein, serum ferritin, procalcitonin, N-terminal pro B-type natriuretic peptide, interleukin-6 level, and D-dimers. There was a statistically significant correlation between degree of elevation in cardiac and biochemical parameters and the need for intensive care support (P<0.05). Polymerase chain reaction for severe acute respiratory syndrome coronavirus 2 was positive in 33.6%, whereas immunoglobulin M and immunoglobulin G antibodies were positive in 15.7% cases and immunoglobulin G in 43.6% cases, respectively, when checked. One child in the study cohort died. CONCLUSIONS: Cardiac involvement is common in children with multisystem inflammatory syndrome associated with the Covid-19 pandemic. The majority of children have significantly raised levels of N-terminal pro B-type natriuretic peptide, ferritin, D-dimers, and cardiac troponin in addition to high C-reactive protein and procalcitonin levels. In comparison with adults with COVID-19, mortality in children with multisystem inflammatory syndrome associated with COVID-19 is uncommon despite multisystem involvement, very elevated inflammatory markers, and the need for intensive care support.

The Use of Virtual Reality Echocardiography in Medical Education.

Virtual reality (VR) is a relatively new technology that allows an individual to experience a virtual world. This new immersive video type may be of particular usefulness in procedure-based healthcare settings. We hypothesized that VR echocardiography was non-inferior to live demonstration. Our aim was to assess the usefulness of a VR echocardiographic approach in teaching echocardiography to pediatric trainees compared to live demonstration. This was a single center, cross-sectional observational design. We used a Garmin VIRB® 360 and a head-mount display to record live echocardiography exams in a pediatric population. An Oculus Go™ was used to view the 360° immersive/VR videos. Trainees responded to a written questionnaire afterwards. Fifteen trainees participated in the study, each of whom had previously seen echocardiography through live demonstration teaching. Eleven respondents had previous hands-on echocardiography experience. All 15 participants confirmed that VR echocardiography is a useful teaching tool with 87% (n = 13) rating it as good or very good on a 5-point Likert scale. When asked to compare VR to live demonstration, 67% (n = 10) rated VR echocardiography as the same or better than live demonstration. One of the participants reported a side effect, namely mild and self-resolving dizziness. VR echocardiography is a safe, inexpensive and practical way for trainees to learn echocardiography. The addition of VR echocardiography to the arsenal of teaching tools may enrich the learning experience for trainees.

Change in collateral ligament length and tibiofemoral movement following joint line variation in TKA.

PURPOSE: The primary intent of total knee arthroplasty is the restoration of normal knee kinematics, with ligamentous constraint being a key influential factor. Displacement of the joint line may lead to alterations in ligament attachment sites relative to knee flexion axis and variance of ligamentous constraints on tibiofemoral movement. This study aimed to investigate collaterals strains and tibiofemoral kinematics with different joint line levels. METHODS: A previously validated knee model was employed to analyse the change in length of the collateral ligaments and tibiofemoral motion during knee flexion. The models shifted the joint line by 3 and 5 mm both proximally and distally from the anatomical level. The data were captured from full extension to flexion 135°. RESULTS: The elevated joint line revealed a relative increase in distance between ligament attachments for both collateral ligaments in comparison with the anatomical model. Also, tibiofemoral movement decreased with an elevation in the joint line. Conversely, lowering the joint line led to a significant decrease in distance between ligament attachments, but greater tibiofemoral motion. CONCLUSION: Elevation of the joint line would strengthen the capacity of collateral ligaments for knee motion constraint, whereas a distally shifted joint line might have the advantage of improving tibiofemoral movement by slackening the collaterals. It implies that surgeons can appropriately change the joint line position in accordance with patient's requirement or collateral tensions. A lowered joint line level may improve knee kinematics, whereas joint line elevation could be useful to maintain knee stability. LEVEL OF EVIDENCE: V.

Prospective masked comparison of intraoperative floppy iris syndrome severity with tamsulosin versus alfuzosin.

OBJECTIVE: To determine whether severe intraoperative floppy iris syndrome (IFIS) is more or equally likely with tamsulosin or alfuzosin. DESIGN: Prospective, masked, multicenter, cross-sectional study. PARTICIPANTS AND CONTROLS: Consecutive patients taking systemic tamsulosin or alfuzosin and scheduled for routine cataract surgery (case group) and patients with no history of systemic α1-antagonists scheduled for routine cataract surgery (control group). METHODS: Phacoemulsification with intraocular lens implantation was performed and recorded on video. Intracameral phenylephrine or epinephrine, either by direct injection or placement in the irrigation bottle, was not permitted. Every surgical video subsequently was reviewed remotely by 2 masked investigators who diagnosed the presence or absence of IFIS and graded the severity of IFIS as follows: none, mild (billowing only), moderate (billowing and either iris prolapse or ≥2 mm of pupil constriction), or severe (billowing accompanied by iris prolapse and ≥2 mm of pupil constriction). MAIN OUTCOME MEASURES: Rate and severity of IFIS and surgical complication rate. RESULTS: A total of 226 eyes (70 in the tamsulosin group, 43 in the alfuzosin group, and 113 in the control group) were enrolled. Severe IFIS was noted in 34.3% (24/70) of the tamsulosin eyes and in 16.3% (7/43) of the alfuzosin eyes compared with 4.4% (5/113) of the control eyes. The differences between each of the 3 groups were statistically significant. In the absence of epinephrine in the irrigation bottle, 12.4% of control eyes had moderate to severe IFIS. There were no instances of posterior capsular rupture or significant surgical complications in either the case or control groups. CONCLUSIONS: Moderate to severe IFIS can occur in low-risk eyes when epinephrine is omitted from the irrigation bottle. Although both tamsulosin and alfuzosin significantly increase the risk of IFIS compared with patients without prior α1-antagonist intake, severe IFIS statistically was more likely with tamsulosin than with alfuzosin (P = 0.036). Patients with symptomatic benign prostatic hyperplasia and cataracts requiring a uroselective α1-antagonist may consider trying alfuzosin first.

Is there a link between open-angle glaucoma and dementia? The Three-City-Alienor cohort.

OBJECTIVE: Previous research has suggested an association between dementia and glaucoma through common risk factors or mechanisms. Our aim was to evaluate the longitudinal relationship between open-angle glaucoma (OAG) and incident dementia. METHODS: The Three-City-Bordeaux-Alienor study is a population-based cohort of 812 participants with a 3-year follow-up period. All participants were aged 72 years or older. An eye examination was performed on all subjects. An OAG was determined based on optic nerve damage and visual field loss. Incident dementia was actively screened for and confirmed by a neurologist. RESULTS: A total of 41 participants developed dementia over the 3-year follow-up period. Future incident dementia cases had an increased prevalence of OAG (17.5% vs 4.5% for nondemented participants, p = 0.003). After adjustment for age, gender, education, family history of glaucoma, vascular comorbidities, and apolipoprotein ε4, our results showed that participants with an OAG were four times more likely to develop dementia during the 3-year follow-up period (odds ratio = 3.9, 95% confidence interval = 1.5-10.4, p = 0.0054). An increased risk of dementia was also associated with 2 markers of optic nerve degeneration (vertical cup:disk ratio and minimal rim:disk ratio). However, no association was found between a high intraocular pressure and/or the use of intraocular pressure-lowering medications and incident dementia. INTERPRETATION: If the association between OAG and dementia is confirmed, direct and noninvasive quantification of the amount of retinal ganglion cell axonal loss may be a useful biomarker of cerebral axonal loss in the future. It may also offer new breakthroughs in understanding the underlying pathophysiological mechanisms of both diseases.

Potential of FTIR spectroscopy for analysis of tears for diagnosis purposes.

It has been widely reported that the tear film, which is crucially important as a protective barrier of the eye, undergoes biochemical changes as a result of a wide range of ocular pathology. This tends to suggest the possibility of early detection of ocular diseases on the basis of biochemical analysis of tears. However, studies of tears by conventional methods of biomolecular and biochemical analysis are often limited by methodological difficulties. Moreover, such analysis could not be applied in the clinic, where structural and morphological analyses by, mainly, slit-lamp biomicroscopy remains the recommended method. In this study, we assessed, for the first time, the potential of FTIR spectroscopy combined with advanced chemometric processing of spectral data for analysis of raw tears for diagnosis purposes. We first optimized sampling and spectral acquisition (tears collection method, tear sample volume, and preservation of the samples) for accurate spectral measurement. On the basis of the results, we focused our study on the possibility of discriminating tears from normal individuals from those of patients with different ocular pathologies, and showed that the most discriminating spectral range is that corresponding to variations of CH2 and CH3 of lipid aliphatic chains. We also report more subtle discrimination of tears from patients with keratoconus and those from patients with non-specific inflammatory ocular diseases, on the basis of variations in spectral ranges attributed notably to lipid and carbohydrate vibrations. Finally, we also succeeded in distinguishing tears from patients with early-stage and late-stage keratoconus on the basis of spectral features attributed to protein structure. Therefore, this study strongly suggests that FTIR spectral analysis of tears could be developed as a valuable and cost-saving tool for biochemical-based detection of ocular diseases, potentially before the appearance of the first morphological signs of diseases. Combined with supervised modelling methods and with use of a spectral data base acquired for representative patients, such a spectral approach could be a useful addition to current methods of clinical analysis for improvement of patient care.

High concentrations of plasma n3 fatty acids are associated with decreased risk for late age-related macular degeneration.

High dietary intakes of n3 (ω3) polyunsaturated fatty acids (PUFA) and fish have been consistently associated with a decreased risk for age-related macular degeneration (AMD). We assessed the associations of late AMD with plasma n3 PUFA, a nutritional biomarker of n3 PUFA status. The Antioxydants Lipides Essentiels Nutrition et Maladies Occulaires (Alienor) Study is a prospective, population-based study on nutrition and age-related eye diseases performed in 963 residents of Bordeaux (France) aged ≥73 y. Participants had a first eye examination in 2006-2008 and were followed for 31 mo on average. Plasma fatty acids were measured by GC from fasting blood samples collected in 1999-2001. AMD was graded from non-mydriatic color retinal photographs at all examinations and spectral domain optical coherence tomography at follow-up. After adjustment for age, gender, smoking, education, physical activity, plasma HDL-cholesterol, plasma triglycerides, CFH Y402H, apoE4, and ARMS2 A69S polymorphisms, and follow-up time, high plasma total n3 PUFA was associated with a reduced risk for late AMD [OR = 0.62 for 1-SD increase (95% CI: 0.44-0.88); P = 0.008]. Associations were similar for plasma 18:3n3 [OR = 0.62 (95% CI: 0.43-0.88); P = 0.008] and n3 long-chain PUFA [OR = 0.65 (95% CI: 0.46-0.92); P = 0.01]. This study gives further support to the potential role of n3 PUFAs in the prevention of late AMD and highlights the necessity of randomized clinical trials to determine more accurately the value of n3 PUFAs as a means of reducing AMD incidence.

Influence of the reference surface shape for discriminating between normal corneas, subclinical keratoconus, and keratoconus.

PURPOSE: To compare the discriminating ability of corneal elevation generated by a dual Scheimpflug analyzer calculated with different reference surfaces for distinguishing normal corneas from those with keratoconus and subclinical keratoconus. METHODS: A total of 391 eyes of 208 patients were prospectively enrolled in the study and divided into three groups: 167 eyes of 113 patients with keratoconus, 47 contralateral topographically normal eyes of patients with clinically evident keratoconus in the fellow eye, and 177 eyes of 95 refractive surgery candidates with normal corneas. All eyes were measured with a dual Scheimpflug analyzer (GALILEI Analyzer; Ziemer Ophthalmic Systems AG, Port, Switzerland). Maximum elevation values were recorded within the central 5-mm diameter in both anterior and posterior elevation maps. Discriminating ability of corneal elevation measurements obtained by best-fit toric and aspheric (BFTA) and best-fit sphere (BFS) reference surfaces were compared by receiver operator characteristic (ROC) curves. RESULTS: ROC curve analysis showed that corneal elevation measured by BFTA had a significantly better ability than with BFS for distinguishing normal corneas from those with keratoconus and forme fruste keratoconus (P = .01). Posterior elevation measured by BFTA had a significantly higher predictive accuracy for forme fruste keratoconus than anterior elevation with an area under ROC curves of 0.88 and 0.80, respectively (P = .01). The sensitivity and specificity achieved with the maximum posterior elevation for detecting keratoconus and forme fruste keratoconus were 99% and 99% for keratoconus and 82% and 80% for forme fruste keratoconus with the cut-off value at 16 and 13 µm, respectively. CONCLUSIONS: The ability to discriminate between normal cornea and forme fruste keratoconus with elevation parameters was significantly improved by using BFTA instead of BFS reference surface.

Strategies to Aid Successful Transition of Adolescents with Congenital Heart Disease: A Systematic Review.

The majority of patients born with congenital heart disease (CHD) need lifelong surveillance with serial clinical attendance and examinations. However, loss of follow-up (namely no documented follow-up for 3 years or more) is a recognised common problem since it is often related to remarkable worsening in the health of CHD patients with increased morbidity and mortality. Transitioning from paediatric to adult care has proven to be the most vulnerable point in the care of these subjects. As such, a systematic review was carried out to ask the following questions: What is the percentage of loss of follow-up worldwide? Are there regional fluctuations in the percentage? Is there a link between loss of follow-up and the complexity of CHD? What strategies should be employed to lower the risk of discontinuity in care? The most recent worldwide averaged loss of follow-up is 26.1%, with significant fluctuations across continents and countries. This percentage is even higher (31.9%) when one includes all untraceable patients, presuming that they are not having any cardiac follow-up. The highest discontinuity of care was reported in the USA and in patients with simple CHD. Planning the rules of transition seems to be one of the most reliable tools to minimise the number of CHD patients who are lost in transition. Recalling patients, with general practitioners who are crucial in readdressing half of the lost to follow-up CHD patients to adult CHD specialists, and a good relationship between paediatric cardiologists and the adult CHD team are two other valuable strategies in aiding successful transition.

Echocardiographic Parameters for Risk Prediction in Borderline Right Ventricle: Review with Special Emphasis on Pulmonary Atresia with Intact Ventricular Septum and Critical Pulmonary Stenosis.

The aim of the present review is to highlight the strengths and limitations of echocardiographic parameters and scores employed to predict favorable outcome in complex congenital heart diseases (CHDs) with borderline right ventricle (RV), with a focus on pulmonary atresia with intact ventricular septum and critical pulmonary stenosis (PAIVS/CPS). A systematic search in the National Library of Medicine using Medical Subject Headings and free-text terms including echocardiography, CHD, and scores, was performed. The search was refined by adding keywords "PAIVS/CPS", Ebstein's anomaly, and unbalanced atrioventricular septal defect with left dominance. A total of 22 studies were selected for final analysis; 12 of them were focused on parameters to predict biventricular repair (BVR)/pulmonary blood flow augmentation in PAIVS/CPS. All of these studies presented numerical (the limited sample size) and methodological limitations (retrospective design, poor definition of inclusion/exclusion criteria, variability in the definition of outcomes, differences in adopted surgical and interventional strategies). There was heterogeneity in the echocardiographic parameters employed and cut-off values proposed, with difficultly in establishing which one should be recommended. Easy scores such as TV/MV (tricuspid/mitral valve) and RV/LV (right/left ventricle) ratios were proven to have a good prognostic accuracy; however, the data were very limited (only two studies with <40 subjects). In larger studies, RV end-diastolic area and a higher degree of tricuspid regurgitation were also proven as accurate predictors of successful BVR. These measures, however, may be either operator and/or load/pressure dependent. TV Z-scores have been proposed by several authors, but old and heterogenous nomograms sources have been employed, thus producing discordant results. In summary, we provide a review of the currently available echocardiographic parameters for risk prediction in CHDs with a diminutive RV that may serve as a guide for use in clinical practice.

Idiopathic Pulmonary Arterial Hypertension in Paediatrics Represents Still a Serious Challenge: A Case Series Study.

INTRODUCTION: Paediatric pulmonary hypertension (PH) represents a heterogeneous illness that is responsible for high morbidity and mortality if left without treatment. Idiopathic pulmonary arterial hypertension (IPAH) is a subtype of PAH rarely seen in paediatrics. Limited long-term data are available. METHODS: Over a period of 20 years, 10 paediatric patients were enrolled at two tertiary centres. Their clinical, echocardiographic, and right heart catheterisation (RHC) features and outcome were evaluated. RESULTS: The mean age at first diagnosis was 5.7 ± 5.7 years. The age at the last follow-up was 12.4 ± 6.1 years. The average follow-up was 6.6 ± 0.8 years. There was a female prevalence of 60% (p < 0.05) in this case series. Regarding the NYHA functional class, 80% of IPAH subjects were in class III or IV. The mean saturation was 91 ± 5%. In this regard, 70% of the patients were on a combination of three drugs, with sildenafil (90%) included. On echocardiography, longitudinal right ventricular contractility (TAPSE) was slightly reduced (13.4 ± 2.6 mm), whilst RVSP was severely elevated (101 ± 19 mmHg). The RHC data showed that mPAP was 61.8 ± 23.1 mmHg (p = 0.0017 with RVSP on echocardiography), mRAP was 10.7 ± 3.8 mmHg, CI was 2.6 ± 1 L·min-1·m-2, PVRi was 16.8 ± 12.6 WU·m2, and SVO2 was 63.6 ± 14.8%. Regarding the outcome, two male IPAH patients (20%) died, and 50% underwent lung transplant or were on transplant assessment or already on the waiting list for lung transplantation. One patient underwent a ductus arteriosus stenting (reverse Potts shunt) and another underwent atrial septostomy and stenting. CONCLUSIONS: Notwithstanding the progress in medical therapy, IPAH continues to represent a serious challenge, particularly in the paediatric population, with the need for lung transplantation and significant mortality.

Refractive and topographic stability of Intacs in eyes with progressive keratoconus: five-year follow-up.

PURPOSE: To evaluate the long-term rate of progression of keratoconus in eyes implanted with Intacs (Addition Technology Inc) at 5-year follow-up. METHODS: Data of 105 eyes from 85 patients who had undergone consecutive Intacs implantation between January 2001 and December 2005 were studied retrospectively for progression of keratoconus. Progression of keratoconus was defined as an increase in steep keratometry (K) of ≥ 1.00 diopter (D) over 4 years between 1- and 5-year follow-up. All eyes were categorized into three subgroups: eyes with documented preoperative progression (change in steep K ≥ 1.00 D over 12 months preoperatively), eyes with documented absence of preoperative progression, and eyes with no record of preoperative progression. RESULTS: Ninety-two eyes were available for analysis. Overall, 91.3% (84/92) of eyes demonstrated no progression between 1- and 5-year follow-up. In the sub-group analysis, 92.9% (52/56) of eyes with documented preoperative progression demonstrated no progression. Additionally, no statistically significant differences were noted in mean steep, flat, and average keratometry; manifest refraction spherical equivalent; and uncorrected and corrected distance visual acuity (P>.05) between 1- and 5-year follow-up. CONCLUSIONS: Results of our study demonstrate the long-term stability of refractive and topographic outcomes following Intacs implantation in eyes with keratoconus. The finding that 92.9% of eyes with progressive keratoconus did not progress postoperatively indicates that Intacs implantation may be a potential therapeutic option to halt progressive keratoconus.

Corneal confocal microscopy following conventional, transepithelial, and accelerated corneal collagen cross-linking procedures for keratoconus.

PURPOSE: To compare early corneal healing following conventional, transepithelial, and accelerated corneal collagen cross-linking (CXL) protocols. METHODS: Twenty-four patients with progressive keratoconus were divided into three groups to receive conventional, transepithelial, or accelerated CXL. In vivo corneal confocal microscopy was performed on each patient preoperatively and at 1, 3, and 6 months postoperatively. RESULTS: Closure of the epithelial wound was complete 3 days following conventional and accelerated CXL. The subbasal nerve plexus was essentially obliterated immediately following conventional and accelerated CXL, and virtually no nerve fibers had regenerated by 6 months. The anterior stroma showed significant changes 1 month following conventional CXL; these changes were similar but more pronounced following accelerated CXL. Observed stromal changes included complete obliteration of keratocytes, increased tissue reflectivity, a honeycomb-like appearance, and circular lacunae. Some recovery of keratocyte density was noted after 6 months. These changes were less pronounced in the mid-stroma, and there were no apparent changes to the posterior stroma or endothelium. The cornea appeared to be unaltered following transepithelial CXL. CONCLUSIONS: In vivo corneal confocal microscopy analysis of the postoperative impact of CXL on the cornea revealed clear differences among conventional, accelerated, and transepithelial CXL protocols. Accelerated CXL had a greater impact than conventional CXL on the anterior cornea, whereas transepithelial CXL did not appear to alter corneal morphology.

Catalytic Conversion of Alkenes on Acidic Zeolites: Automated Generation of Reaction Mechanisms and Lumping Technique.

Acid-catalyzed hydrocarbon transformations are essential for industrial processes, including oligomerization, cracking, alkylation, and aromatization. However, these chemistries are extremely complex, and computational (automatic) reaction network generation is required to capture these intricacies. The approach relies on the concept that underlying mechanisms for the transformations can be described by a limited number of reaction families applied to various species, with both gaseous and protonated intermediate species tracked. Detailed reaction networks can then be tailored to each industrially relevant process for better understanding or for application in kinetic modeling, which is demonstrated here. However, we show that these networks can grow very large (thousands of species) when they are bound by typical carbon number and rank criteria, and lumping strategies are required to decrease computational expense. For acid-catalyzed hydrocarbon transformations, we propose lumping isomers based on carbon number, branch number, and ion position to reach high carbon limits while maintaining the high resolution of species. Two case studies on propene oligomerization verified the lumping technique in matching a fully detailed model as well as experimental data.

Glistenings on intraocular lenses in healthy eyes: effects and associations.

PURPOSE: To assess glistenings in AcrySof (Alcon Laboratories Inc) intraocular lenses (IOLs), to quantify any effects of glistenings on the visual function of patients with healthy eyes, and to investigate whether glistenings were associated with demographic or lens characteristics. METHODS: Case files from a consecutive series of healthy eyes were retrospectively analyzed. Subjective glistening grades were investigated for associations with the following parameters: contrast sensitivity, corrected distance visual acuity (CDVA), intraocular light scattering (measured by C-Quant [Oculus Optikgeräte GmbH]), posterior capsule opacification, demographic characteristics, lens power, and duration of pseudophakia. The subjective grading method was compared to objective software-based quantitation of glistenings. RESULTS: The study cohort included 97 eyes from 65 patients with a mean age of 65 ± 11 years. Mean follow-up was 18 ± 17 months. Glistening grades did not vary by duration of pseudophakia (P=.19), although study design limited confidence in this result. Glistening grades had no associations with lens power (P=.41), intraocular light scattering (P=.31), logMAR CDVA (P=.64), contrast sensitivity at any spatial frequency (all P ≥.22), or with any other parameter under investigation. The software-based assessment confirmed the validity of the subjective grading method: glistening grades correlated with vacuoles/mm(2) (P<.0001) and mean values for vacuoles/mm(2) were statistically significant for each glistening grade (all P ≤.004). CONCLUSIONS: In healthy eyes, glistening grade was not associated with contrast sensitivity, CDVA, intraocular light scatter, or any lens or demographic characteristics that were investigated.

Interface fluid syndrome after bioptics.

PURPOSE: To report an unusual case of interface fluid syndrome after refractive surgery. METHODS: A 37-year-old man with high myopia underwent a planned bioptics procedure including creation of a corneal flap using a mechanical microkeratome and concurrent anterior chamber phakic intraocular lens implantation; excimer laser ablation was not performed at this time. RESULTS: Postoperatively, the patient developed corneal edema and was referred to our department. Interface fluid syndrome was confirmed using optical coherence tomography; the mechanism was due to endothelial cell pump dysfunction. CONCLUSIONS: This is the first report to document interface fluid syndrome following a planned bioptics procedure.

Indices for the detection of keratoconus.

Identification of keratoconus has become a step of primary importance in the preoperative evaluation for the refractive surgery. In order to decrease the secondary ectasia after refractive surgery the preoperative screening of keratoconus is very important. Corneal topography, the most useful tool in the diagnosis of keratoconus, offer us the possibility of an early diagnosis of KC by a lot of mathematical indices calculate to determine the disease with a higher specificity and sensitivity. Although useful, these indices may be difficult to understand and use.

An in-vitro evaluation of the flow haemodynamic performance of Gore-Tex extracardiac conduits for univentricular circulation.

OBJECTIVE(S): The Fontan procedure is a common palliative intervention for sufferers of single ventricle congenital heart defects that results in an anastomosis of the venous return to the pulmonary arteries called the total cavopulmonary connection (TCPC). In patients with palliated single ventricular heart defects, the Fontan circulation passively directs systemic venous return to the pulmonary circulation in the absence of a functional sub-pulmonary ventricle. Therefore, the Fontan circulation is highly dependent on favourable flow and energetics, and minimal energy loss is of great importance. The majority of in vitro studies, to date, employ a rigid TCPC model. Recently, few studies have incorporated flexible TCPC models, without the inclusion of commercially available conduits used in these surgical scenarios. METHOD: The methodology set out in this study successfully utilizes patient-specific phantoms along with the corresponding flowrate waveforms to characterise the flow haemodynamic performance of extracardiac Gore-Tex conduits. This was achieved by comparing a rigid and flexible TCPC models against a flexible model with an integrated Gore-Tex conduit. RESULTS: The flexible model with the integrated Gore-Tex graft exhibited greater levels of energy losses when compared to the rigid walled model. With this, the flow fields showed greater levels of turbulence in the complaint and Gore-Tex models compared to the rigid model under ultrasound analysis. CONCLUSION: This study shows that vessel compliance along with the incorporation of Gore-Tex extracardiac conduits have significant impact on the flow haemodynamics in a patient-specific surgical scenario.