bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of attributable risk for case‐control studies with multiple matching
Authors: Lui Kung‐Jong
Published: September 2005

Kuritz and Landis considered case‐control studies with multiple matching and proposed an asymptotic interval estimator of the attributable risk based on Wald's statistic. Using Monte Carlo simulation, Kuritz and Landis demonstrated that their interval estimator could perform well when the number of matched sets was large (⩾100). However, the number of matched sets may often be moderate or small in practice. In this paper, we evaluate the performance of Kuritz and Landis' interval estimator in small or moderate number of matched sets and compare it with four other interval estimators. We note that the coverage probability of Kuritz and Landis' interval estimator tends to be less than the desired confidence level when the probability of exposure among cases is large. In these cases, the interval estimator using the logarithmic transformation and the two interval estimators derived from the quadratic equations developed here can generally improve the coverage probability of Kuritz and Landis' interval estimator, especially for the case of a small number of matched sets. Furthermore, we find that an interval estimator derived from a quadratic equation is consistently more efficient than Kuritz and Landis' interval estimator. The interval estimator using the logit transformation, although which performs poorly when the underlying odds ratio (OR) is close to 1, can be useful when both the probability of exposure among cases and the underlying OR are moderate or large. Copyright © 2005 John Wiley & Sons, Ltd.
Influence diagnostics for two‐component Poisson mixture regression models: applications in public health
Authors: Xiang Liming , Yau Kelvin K. W. , Lee Andy H. , Fung Wing K.
Published: September 2005

In many medical and health applications, Poisson mixture regression models are commonly used to analyse heterogeneous count data. Motivated by two data sets drawn from public health studies, influence diagnostics are proposed for assessing the sensitivity of the fitted two‐component Poisson mixture regression models. Under various perturbations of the observed data or model assumptions, influence assessments based on the local influence approach are developed for detecting clusters and/or individual observations that impact on the estimation of model parameters. Results from studies on recurrent urinary tract infections and maternity length of stay illustrate the usefulness of the influence diagnostics. Copyright © 2005 John Wiley & Sons, Ltd.
Sample‐size calculations for studies with correlated ordinal outcomes
Authors: Kim Hae‐Young , Williamson John M. , Lyles Cynthia M.
Published: September 2005

Correlated ordinal response data often arise in public health studies. Sample‐size (power) calculations are a crucial step in designing such studies to ensure an adequate sample to detect a significant effect. Here we extend Rochon's method of sample‐size estimation with a repeated binary response to the ordinal case. The proposed sample‐size calculations are based on an analysis with generalized estimating equations (GEE) and inference with the Wald test. Simulation results demonstrate the merit of the proposed power calculations. Analysis of an arthritis clinical trial is used for illustration. Published in 2005 by John Wiley & Sons, Ltd.
Adjusting for treatment effects in studies of quantitative traits: antihypertensive therapy and systolic blood pressure
Authors: Tobin Martin D. , Sheehan Nuala A. , Scurrah Katrina J. , Burton Paul R.
Published: September 2005

A population‐based study of a quantitative trait may be seriously compromised when the trait is subject to the effects of a treatment. For example, in a typical study of quantitative blood pressure (BP) 15 per cent or more of middle‐aged subjects may take antihypertensive treatment. Without appropriate correction, this can lead to substantial shrinkage in the estimated effect of aetiological determinants of scientific interest and a marked reduction in statistical power. Correction relies upon imputation, in treated subjects, of the underlying BP from the observed BP having invoked one or more assumptions about the bioclinical setting. There is a range of different assumptions that may be made, and a number of different analytical models that may be used. In this paper, we motivate an approach based on a censored normal regression model and compare it with a range of other methods that are currently used or advocated. We compare these methods in simulated data sets and assess the estimation bias and the loss of power that ensue when treatment effects are not appropriately addressed. We also apply the same methods to real data and demonstrate a pattern of behaviour that is consistent with that in the simulation studies. Although all approaches to analysis are necessarily approximations, we conclude that two of the adjustment methods appear to perform well across a range of realistic settings. These are: (1) the addition of a sensible constant to the observed BP in treated subjects; and (2) the censored normal regression model. A third, non‐parametric, method based on averaging ordered residuals may also be advocated in some settings. On the other hand, three approaches that are used relatively commonly are fundamentally flawed and should not be used at all. These are: (i) ignoring the problem altogether and analysing observed BP in treated subjects as if it was underlying BP; (ii) fitting a conventional regression model with treatment as a binary covariate; and (iii) excluding treated subjects from the analysis. Given that the more effective methods are straightforward to implement, there is no argument for undertaking a flawed analysis that wastes power and results in excessive bias. Copyright © 2005 John Wiley & Sons, Ltd.
Do policies matter?
Authors: Zemsky Beth , Sanlo Ronni L.
Published: September 2005

This chapter provides an overview of nondiscrimination policies that include sexual orientation and gender identity and addresses how such policies might be used to improve campus climates for LGBT students, faculty, and staff.
Campus climates for sexual minorities
Authors: Rankin Susan R.
Published: September 2005

Sexual minorities encounter unique challenges due to their sexual orientation, gender identity, or gender expression that often prevents them from achieving their full academic potential or participating fully in the campus community.
Analysis of LGBT identity development models and implications for practice
Authors: Bilodeau Brent L. , Renn Kristen A.
Published: September 2005

A review of LGBT identity development models reveals fluidity, complexity, and contradictions.
LGBT students in community college: Characteristics, challenges, and recommendations
Authors: Ivory Brian T.
Published: September 2005

Due to the transitory nature of students at community colleges, it is often difficult for student affairs professionals to connect with LGBT students and even more difficult for them to provide services for this invisible population.
The evolution of an LGBT center at a public institution
Authors: Ryan Robin
Published: September 2005

There are many ways in which a campus LGBT office or center can be established. This chapter tells the story of one institution's journey to creating such a center and the tools used to make that creation happen.
The role of senior student affairs officers in supporting LGBT students: Exploring the landscape of one's life
Authors: Roper Larry D.
Published: September 2005

As leaders and community builders, senior student affairs officers face the challenge to end the hostility, oppression, and invisibility that often characterize the experiences of LGBT students on college campuses.
Setting the stage for identity, learning, and the liberal arts
Authors: Laff Ned Scott
Published: September 2005

This chapter argues that liberal learning can be transformative and foster students' intellectual and ethical development only if we consider its development underpinnings and pedagogic strategies that illustrate that the skills of academic inquiry are the skills of personal development.
Reshaping their views: Science as liberal arts
Authors: Bramble Judith
Published: September 2005

General‐education science courses should provide students with a foundation of knowledge about how the natural world works, a clear understanding of the nature of science and scientific inquiry, and an appreciation for the relationship between science and society. This chapter suggests a variety of approaches to engage students in their own learning and, with appropriate reflection, help them construct more scientific worldviews.
Pedagogy and practice: Service‐learning and students' moral development
Authors: Strain Charles R.
Published: September 2005

Service‐learning courses can be powerful instruments for cognitive, affective, and moral transformation. This chapter examines the strengths and weaknesses of service‐learning as an agent for cognitive, moral, and interpersonal development and its ability to promote civic or social engagement.
Ultrasound dating at 12–14 weeks of gestation. A prospective cross‐validation of established dating formulae in in‐vitro fertilized pregnancies
Authors: Sladkevicius P. , Saltvedt S. , Almström H. , Kublickas M. , Grunewald C. , Valentin L.
Published: September 2005

Objectives

To determine the accuracy of established ultrasound dating formulae when used at 12–14 weeks of gestation.

Methods

One‐hundred and sixty‐seven singleton pregnancies conceived after in‐vitro fertilization (IVF) underwent a dating scan at 12–14 weeks of gestation. Gestational age at the dating scan was calculated by adding 14 days to the number of days between the date of oocyte retrieval and the date of the ultrasound scan. Gestational age according to oocyte retrieval was regarded as the true gestational age. True gestational age was compared to gestational age calculated on the basis of 21 dating formulae based on fetal crown–rump length (CRL) measurements and to three dating formulae based on fetal biparietal diameter (BPD) measurements. In a previous study the three BPD formulae tested here had been shown to be superior to four other BPD formulae when used at 12–14 weeks of gestation. The mean of the differences between estimated and true gestational age and their standard deviation (SD) were calculated for each formula. The SD of the differences was assumed to reflect random measurement error. Systematic measurement error was assumed to exist if zero lay outside the mean difference ± 2SE (SE: standard error of the mean).

Results

The three best CRL formulae were associated with mean (non‐systematic) measurement errors of −0.0, −0.1 and −0.3 days, and the SD of the measurement errors of these formulae varied from 2.37 to 2.45. All but two of the remaining CRL formulae were associated with systematic over‐ or under‐estimation of gestational age, and the SDs of their measurement error varied between 2.25 and 4.86 days. Dating formulae using BPD systematically underestimated gestational age by −0.4 to −0.7 days, and the SDs of their measurement errors varied from 1.86 to 2.09.

Conclusions

We have identified three BPD formulae that are suitable for dating at 12–14 weeks of gestation. They are superior to all 21 CRL formulae tested here, because their random measurement errors were much smaller than those of the three best CRL formulae. The small systematic negative measurement errors associated with the BPD formulae are likely to be clinically unimportant. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Roles of dispersal, stochasticity, and nonlinear dynamics in the spatial structuring of seasonal natural enemy–victim populations
Authors: Tobin Patrick C. , Bjørnstad Ottar N.
Published: September 2005

Natural enemy–victim systems may exhibit a range of dynamic space–time patterns. We used a theoretical framework to study spatiotemporal structuring in a transient natural enemy–victim system subject to differential rates of dispersal, stochastic forcing, and nonlinear dynamics. Highly mobile natural enemies that attacked less mobile victims were locally spatially segregated from each other when governed by approximate linear dynamics. In contrast, in nonlinear dynamical systems, such as cyclic populations, interacting species achieved local aggregation with each other regardless of dispersal rates, and aggregation was enhanced specifically when highly mobile enemies attacked less mobile victims. These patterns of spatial aggregation held under varying levels of stochastic forcing. This work thus shows a range of dynamic spatial patterns in interacting‐species models, and how spatial aggregation between natural enemies and victims can be achieved in locally unstable populations that are linked through dispersal.
IS ANTENATAL CARE EFFECTIVE IN IMPROVING MATERNAL HEALTH IN RURAL UTTAR PRADESH? EVIDENCE FROM A DISTRICT LEVEL HOUSEHOLD SURVEY
Authors: RAM FAUJDAR , SINGH ABHISHEK
Published: September 2005

Data from the District Level Household Survey (2002) conducted by the Reproductive and Child Health Project in India has been used to examine the impact of utilization of antenatal care services on improvement in maternal health in rural areas of Uttar Pradesh, India. Multilevel analysis shows that after controlling for other socioeconomic and demographic factors, utilization of antenatal care services may lead to the utilization of other maternal health related services such as institutional delivery, delivery assisted by trained professionals, seeking advice for pregnancy complications, and seeking advice for post-delivery complications. There is strong clustering of utilization of services within the primary sampling units (i.e. villages) and districts.
population and the means of subsistence: explaining the historical demography of island southeast asia, with particular reference to sulawesi
Authors: henley david
Published: September 2005

the phenomenon of low population growth in pre-colonial southeast asia is often interpreted in terms of epidemic disease, internecine warfare or cultural idiosyncracies affecting the birth rate. the modern population boom, in these analyses, results from medical and public health improvements, military pacification or foreign cultural influences. this article, by contrast, argues that in indonesia and the philippines population growth has typically been a result of economic growth, and that the general sparsity of the population in early historical times reflected the low ‘carrying capacity’ of the environments in question under the prevailing economic conditions.
brinkmanship and deterrence success during the anglo-indonesian sunda straits crisis, 1964–1966
Authors: kwan toh boon
Published: September 2005

britain and indonesia approached the brink of war at the height of the sunda straits crisis in september 1964. using newly released declassified archival records, this study reviews the supposed british deterrence success. the factors behind successful indonesian deterrence during the crisis contradict the prevalent view that statesmen should refrain from brinkmanship since they are unlikely to achieve their political goals at minimum costs to themselves.
religion and the indonesian constitution: a recent debate
Authors: hosen nadirsyah
Published: September 2005

this article examines the recent debate on the position of syari'ah in indonesian constitutional amendments (1999–2002). the article operates at two levels: a historical review of the debate on islam and state in indonesia and a theoretical effort to situate the indonesian debate in the broader context of debates over islam and constitutions. it argues that the rejection of the proposed amendment to article 29, dealing with islam, has shown that indonesian islam follows the substantive approach of syari'ah, not the formal one.
the new muslim romance: changing patterns of courtship and marriage among educated javanese youth
Authors: smith-hefner nancy j.
Published: September 2005

this article explores changing attitudes towards courtship and marriage among educated muslim javanese youth, as seen against the backdrop of islamic resurgence, growing educational achievement and socioeconomic change. through a comparison of earlier forms of courtship and marriage with emerging trends, it sheds light on some of the tensions and ambivalences surrounding the new social freedoms and autonomy modern javanese women have come to enjoy.
New histochemical techniques for the localization of metal ions in the lichen thallus
Authors: Rinino Simona , Bombardi V. , Giordani P. , Tretiach M. , Crisafulli P. , Monaci F. , Modenesi P.
Published: September 2005

The localization of inorganic contaminants in lichens is an important step toward a better understanding of the accumulating capability and toxitolerance of species (Hauck et al. 2002). Different methods, such as sequential elution technique (Brown 1995; Tretiach et al. 1999), X-ray microanalysis (Hauck et al. 2002) and microscopic histochemistry (Garty & Theiss 1989), have been used.
Manganese as a site factor for epiphytic lichens
Authors: HAUCK Markus , PAUL Alexander
Published: September 2005

Decreasing abundance of epiphytic lichens with increasing Mn supply from the substratum or from stemflow was found in several coniferous forests of Europe (Germany) as well as western (Montana, British Columbia) and eastern North America (New York State). Experiments carried out with Hypogymnia physodes and other species of chloro- and cyano-lichens suggest that these correlations are causal. High Mn concentrations e.g. reduce chlorophyll concentrations, chlorophyll fluorescence and degrade the chloroplast in lichen photobionts. Excess Mn inhibits the growth of soredia of H. physodes and causes damage in the fine- and ultra-structure of the soredia. Adult lichen thalli remain structurally unaffected by Mn. Manganese uptake does not result in membrane damage. Calcium, Mg, Fe and perhaps also Si alleviate Mn toxicity symptoms in H. physodes. Lecanora conizaeoides is not sensitive to Mn in laboratory experiments or in the field. The data suggest that high Mn concentrations are an important site factor for epiphytic lichens in coniferous forests that until recently has been overlooked. Manganese reaching the microhabitat of epiphytic lichens is primarily soil-borne and is usually not derived from pollution.
Visualized photosynthetic characteristics of the lichen Xanthoria elegans related to daily courses of light, temperature and hydration: a field study from Galindez Island, maritime Antarctica
Authors: BARTÁK M. , GLOSER J. , HÁJEK J.
Published: September 2005

Diurnal courses of photosystem II (PS II) activity of Xanthoria elegans were continuously monitored using a novel technique of chlorophyll fluorescence imaging in the field (maritime Antarctica) over a period of 7 days. The lichen specimens grew on rock surfaces in a north-facing coastal area of Galindez Island (Argentine Islands). A portable fluorometer FluorCam equipped with a CCD camera and image analysis software was placed over a thallus so that false colour images of FV/FM and quantum yield of photochemical processes in PS II (ΦII) distribution over the thallus could be taken over the course of a day. Simultaneously, microclimatic parameters of the habitat were recorded: air and thallus temperatures, relative air humidity, PPFR (photosynthetic photon fluence rate) and global radiation. Photosynthetic processes in X. elegans were activated by rainfall or water from melting snow. After thallus hydration, FV/FM and ΦII gradually decreased from their maximum values due to evaporation and progressive loss of water from the thallus. Chlorophyll fluorescence imaging showed that the thallus dehydration started from the margins and moved towards the central thicker thallus zones. These zones exhibited higher activity of PS II than the margins throughout the day. The rate of inhibition of photosynthetic processes in PS II was faster at the margins than in the centre of the thallus. Dependence of ΦII on thallus water potential (WP) was investigated during gradual dehydration under laboratory conditions. After a decrease in WP from zero to −7 MPa, X. elegans exhibited only a 13·8% decrease in ΦII from its maximal value. Within the range of WP of from −8 to −20 MPa, the ΦII decrease was more rapid reaching the critical point (ΦII=0) at WP of approximately −25 MPa. Chlorophyll fluorescence imaging and WP measurements showed that X. elegans is capable of maintaining detectable photosynthetic activity even at extremely low WP. Based on our microclimatological data, X. elegans may be photosynthetically active under field conditions for several hours after being wetted by rain or snowfall. It is suggested that chlorophyll fluorescence imaging is a powerful technique, transferable to field conditions and capable of visualizing heterogeneity of photosyntetic processes over a lichen thallus subjected to periodic dehydration.
Ecology of endolithic lichens colonizing granite in continental Antarctica
Authors: DE LOS RÍOS Asunción , WIERZCHOS Jacek , SANCHO Leopoldo G. , GREEN T. G. Allan , ASCASO Carmen
Published: September 2005

In this study, the symbiont cells of several endolithic lichens colonizing granite in continental Antarctica and the relationships they have with the abiotic environment were analyzed in situ, in order to characterize the microecosystems integrating these lichens, from a microecological perspective. Mycobiont and photobiont cells, the majority classified as living by fluorescent vitality testing, were observed distributed through the fissures of the granite. The fact that extracellular polymeric substances were commonly observed close to these cells and the features of these compounds, suggest a certain protective role for these substances against the harsh environmental conditions. Different chemical, physical and biological relationships take place within the endolithic biofilms where the lichens are found, possibly affecting the survival and distribution of these organisms. The alteration of bedrock minerals and synthesis of biominerals in the proximity of these lichens give rise to different chemical microenvironments and suggest their participation in mineral nutrient cycling.
Isidia ontogeny and its effect on the CO2 gas exchanges of the epiphytic lichen Pseudevernia furfuracea (L.) Zopf
Authors: TRETIACH Mauro , CRISAFULLI Paola , PITTAO Elena , RININO Simona , ROCCOTIELLO Enrica , MODENESI Paolo
Published: September 2005

The development of isidia in thalli of Pseudevernia furfuracea from the Carnic Alps (North-eastern Italy), and the effects of these structures on CO2 gas exchanges were investigated. The ontogenetic events were studied by comparison of sections stained with different histochemical tests and SEM observations. A high cell turnover rate in both symbiotic partners is the first sign of isidium development, followed by an increased aplanosporogenesis of algae and growth of neighbouring medullary hyphae which become oriented upwards. Large nuclei and an intense cytoplasm activity characterize the mycobiont cells. The surface of very young isidia shows an irregular structure of spherical to ovoid protruding tips of perpendicular cortical hyphae, that are later organised in a pseudomeristematic area similar to that observed in the apex of growing lobes. CO2 gas exchange measurements carried out in the laboratory confirmed the high metabolic activity of isidia. At optimal water content and favourable light conditions, isolated isidia had rates of gross photosynthesis and dark respiration that were twice those of non-isidiate lobes. Isolated isidia also had a very low CO2 saturation point, probably because of their favourable surface/volume ratio, and a high light saturation, probably linked to their high content of photosynthetic pigments. The different roles played by isidia in the biology of Pseudevernia furfuracea, and particularly their rejuvenating effect on aged lobes, are discussed, and the presence of thalloconidia is briefly mentioned.
Observing microscopic phases of lichen life cycles on transparent substrata placed in situ
Authors: SANDERS William B.
Published: September 2005

The utility of plastic cover slips as a substratum for in situ study of lichen developmental stages is further explored in a neotropical foliicolous lichen community and in a European temperate corticolous community. Twenty-one months after placement in the tropical forest, the cover slips bore foliicolous lichen thalli with several species producing characteristic ascocarps and ascospores, indicating the suitability of the substratum for completion of the life cycle of these lichens. On cover slips placed within the temperate corticolous community, lichen propagules anchored to the substratum with relatively short attachment hyphae but did not develop further within the one year observation period. Intimately intermixed microbial communities of short-celled, mainly pigmented fungi and chlorophyte algae developed upon the transparent substratum. Among the algae, Trebouxia cells, often in groups showing cell division and without associated lichenizing hyphae, were commonly observed. The potential significance of the free-living populations in the life cycle of Trebouxia and in those of Trebouxia-associated lichen fungi is discussed.
Editorial
Authors: Crittenden Peter D. , Beckett Richard P. , Fahselt Dianne
Published: September 2005

Between 16–21 August 2004, 250 lichenologists gathered in Tartu, Estonia for the Fifth Symposium of the International Association for Lichenology (IAL5). The meeting comprised six principal lecture sessions and associated posters. This issue of The Lichenologist presents papers deriving from contributions to Session 3: Genes, Physiology and Structure. This session probably had the broadest scope of all those comprising the symposium because it essentially encompassed all aspects of the general biology of the lichen thallus. The response to this topic from prospective authors and presenters was excellent and the final programme included fourteen oral presentations and sixteen posters; of this total of thirty contributions, eight are published here. Inevitably, several of the oral and poster presentations were already submitted to, or destined for, alternative journals or were considered too preliminary to warrant publication at this stage. In particular, there were several excellent “molecular” contributions dealing with such topics as breeding systems, genetic diversity, microbial diversity within thalli, and the genetic control of secondary metabolite production, but none were available or offered as papers to this volume.
Tetralogy of Fallot – Introduction
Authors: Gaynor J. William
Published: September 2005

Surgical therapy for tetralogy of fallot is one of the success stories of the early era of cardiac surgery. Despite the many advances of the ensuing fifty years, such as new techniques for imaging, extension of surgical therapy to the neonatal period, and improved treatment in the intensive care unit, there has been an increasing recognition that the outcomes for many patients over the long term remain less than optimal. Mortality for surgical correction of tetralogy of Fallot, even in very small neonates, approaches zero at most institutions. Patients remain at risk, however, for right ventricular dysfunction, congestive heart failure, and an ongoing need for future therapeutic interventions, including cardiac catheterization and re-operation. Surgical reconstruction of the abnormal subpulmonary right ventricular outflow tract often results in pulmonary insufficiency and scarring, leading to ventricular volume overload and dysfunction. Postoperative right ventricular dysfunction may be associated with congestive heart failure, poor exercise tolerance, arrhythmias, and sudden death. The chapters which follow in this section of our supplement focus on the current state of knowledge concerning treatment and management of patients with pulmonary insufficiency following surgical repair of tetralogy of Fallot. There is considerable controversy concerning the clinical significance of pulmonary insufficiency; there is no standard technique for the assessment of right ventricular function; and there are considerable disagreements concerning the optimal timing of surgical re-intervention to replace the pulmonary valve. I believe that the reviews will help clarify these important issues.
The clinical anatomy of tetralogy of Fallot
Authors: Anderson Robert H. , Weinberg Paul M.
Published: September 2005

It is now well over one hundred years since Arthur Louis Etienne Fallot showed that four discrete morphologic abnormalities co-existed in the majority of patients he had autopsied with “la maladie bleu”,1 or cyanosis as we now describe it. The lesions he identified were an interventricular communication, subpulmonary stenosis, biventricular origin of the aortic valve, and right ventricular hypertrophy. We now know that the combination of these anomalies had been recognised long before Fallot's epochal description. Indeed, it is Neils Stensen, the Danish monk who also described the parotid duct, who is usually acknowledged as being the first to describe the entity that we now call tetralogy of Fallot.2 Cases were certainly described by John Hunter,2 whilst with the benefit of hindsight, we can see an unequivocal example illustrated by the Baron von Rokitansky3 in his ground-breaking atlas (Fig. 1).
Echocardiographic determination of right ventricular function
Authors: Boucek Jr Robert J. , Martinez Richard
Published: September 2005

With advances in surgical technique, more children with complex congenital heart disease are surviving.1 Increasingly, attention is focusing on late morbidities, such as right ventricular dysfunction.2 For many common forms of congenital cardiac malformations, the assessment of right ventricular size and function is now essential so as to make optimal decisions concerning management.3 Commonly encountered examples include the timing for operative replacement of the incompetent pulmonary valve following surgical repair of tetralogy of Fallot, and the assessment of suspected ventricular dysfunction in children with functionally single or systemic right ventricles.4 Echocardiography remains the most practical method for serially determining right ventricular function, despite its limitations.5 The easy accessibility of echocardiography has encouraged its continued development as a tool for determining right ventricular function in neonates, infants, and children. A comparison of values established for the right ventricle is shown in Table 1, along with the references from which they were culled. We will describe these values in sequence.
Pulmonary insufficiency: preparing the patient with ventricular dysfunction for surgery
Authors: Bouzas Beatriz , Chang Anthony C. , Gatzoulis Michael A.
Published: September 2005

Insufficiency of any of the four cardiac valves is a common cause of heart failure in children. Progression of ventricular dysfunction can be predictable, but requires thorough understanding of valvar disease. In valvar regurgitation, the heart has to cope with an increased volume of blood. The pathophysiological sequence is similar for both the right and the left heart. There is initially an increase in end-diastolic volume, followed by an increase in end-systolic volume, and at the end, a decrease in the shortening and ejection fractions. Different compensatory mechanisms and pathophysiologic adaptations develop to maintain the stroke volume for each type of valvar insufficiency, but heart failure eventually ensues. When symptoms of heart failure develop, irreversible ventricular dysfunction is often established, and outcome after surgery may ultimately be compromised. Discerning the optimal time for intervention, before irreversible ventricular dysfunction develops, is a key point in the management of regurgitant valvar heart disease.
Late replacement of the pulmonary valve: when and what type of valve?
Authors: Quintessenza James A. , Jacobs Jeffrey P. , Chai Paul J. , Morell Victor O. , Giroud Jorge M. , Boucek Robert J.
Published: September 2005

After repair of tetralogy of Fallot, many patients present in need of reoperative surgical reconstruction of the right ventricular outflow tract. The predominant physiologic lesion is pulmonary insufficiency, but there may also be varying degrees of obstruction of the right ventricular outflow tract. In the past, it has been felt that patients tolerate pulmonary insufficiency reasonably well. In some patients, however, the long-term effects of pulmonary insufficiency and subsequent right ventricular dilation and dysfunction are associated with poor exercise tolerance and increased incidence of arrhythmias and sudden death.1,2 Numerous studies support replacement of the pulmonary valve as treatment for pulmonary insufficiency in order to improve performance, optimize hemodynamics, and better control arrhythmias.3–10 The indications for reconstruction of the right ventricular outflow tract in this setting, nonetheless, as well as the operative strategy, continue to evolve. There are multiple surgical options for replacement of the pulmonary valve for these patients, including aortic and pulmonary homografts, stented and stentless porcine valves, porcine valved conduits, bovine jugular venous conduits, and even mechanical valves and mechanical valved conduits.11–32 It was a less than ideal experience with these currently available options that stimulated our interest into employing alternative materials and techniques. Favorable experimental and clinical experience with valves made of a polytetrafluoroethylene monoleaflet33–36 encouraged us to consider a new method of reconstruction with this material, using a bifoliate polytetrafluoroethylene valve. In this work, we review our indications for replacement of the pulmonary valve after repair of tetralogy of Fallot, the surgical options available, and our experience reconstructing the right ventricular outflow tract with a new surgically created bifoliate polytetrafluoroethylene valve.
Severe pulmonary valvar insufficiency should be aggressively treated
Authors: Backer Carl L.
Published: September 2005

My role in the debate between myself and Bill Gaynor is to substantiate the notion that severe pulmonary valvar insufficiency should be treated in aggressive fashion. This gives me few problems. At Children's Memorial Hospital in Chicago, we have a long tradition of favouring early insertion of new pulmonary valves in patients with significant pulmonary valvar insufficiency following repair of tetralogy of Fallot. Our results with this strategy in the current era were first presented in 1986 at the Western Thoracic Surgical Association.1 At that time, we had inserted pulmonary valves late following repair of tetralogy of Fallot in 42 patients. We postulated that early control of pulmonary insufficiency may prevent long-term deterioration in right ventricular function. The fact that this is a controversial issue became immediately apparent during the discussion of our presentation. Dr. Frank Spencer, from New York, stated “I would completely disagree with the concept of electively inserting a porcine valve in a child on the basis of haemodynamic data. I fear that the approach recommended in this presentation is probably treating one disease by creating a worse one.”
Severe pulmonary insufficiency should be conservatively treated
Authors: Gaynor J. William
Published: September 2005

It's always hard to follow a presentation by Carl Backer. Today, we have heard several presentations about the problem of pulmonary insufficiency. We have been shown multiple images of dilated and poorly functioning right ventricles. The obvious conclusion is that these patients should undergo replacement of the pulmonary valve. I agree with Carl that operative morbidity and mortality for replacing the pulmonary valve is minimal, but we must also consider the outcomes in the long-term. Most physicians would agree that valvar replacement is indicated in a symptomatic patient with right heart failure and exercise intolerance. In order to win this debate, therefore, it will necessary to redirect and alter the question! The question I am going to consider is: “should we replace prophylactically the pulmonary valve in asymptomatic patients with pulmonary insufficiency and right ventricular dilation?
Transposition – Introduction
Authors: Anderson Robert H.
Published: September 2005

In the past, most arguments concerning transposition devolved on how best to define it. When Mathew Baillie described the first case, at the end of the eighteenth century, he had no problems. He simply called it a singular malformation!1 Subsequent to Baillie's description, arguments raged amongst morphologists and pathologists as to whether the entity was best described on the basis of how the aorta was related to the pulmonary trunk, or according to the origin of the arterial trunks from inappropriate ventricles. There is little doubt now that all clinicians diagnose transposition on the basis of discordant origin of the arterial trunks from the ventricular mass, although there is still debate as to whether this discordant origin is best described in terms of connections2 or alignments.3 There remain some, nonetheless, who still describe entities such as “double outlet with transposition”, using this phrase to describe the arrangement in which both arterial trunks arise from the right ventricle, but with the aorta positioned anteriorly. For those adopting the concepts of connections or alignments, this combination is clearly impossible.4 Yet for those who choose to define “transposition” on the basis of the anterior location of the aorta,5 this would remain an entirely logical description. These problems of nomenclature, and many more aspects of the morphology of discordant origin of the arterial trunks from the ventricular mass, are discussed at length in the first review of this part of the supplement,6 co-authored by myself, who believes firmly in the concept of connections, and Paul Weinberg, who is equally convinced that the cardiac segments are best described in terms of alignments rather than connections. Our joint review hopefully shows that differences in nomenclature nowadays are relatively minor, and even where they exist, they do not stand in the way of reaching consensus on how best to describe the segmental combination in which the atrial chambers are joined to morphologically appropriate ventricle, but the ventricles support morphologically inappropriate arterial trunks. It is this particular morphological arrangement that, for the purposes of this section of our supplement, is described as “transposition”.
The clinical anatomy of transposition
Authors: Anderson Robert H. , Weinberg Paul M.
Published: September 2005

It is an easy matter, nowadays, to diagnose the clinical situation in which the blood returning to the atriums passes to the morphologically appropriate ventricle, but in which the ventricles then supply morphologically inappropriate arterial trunks. The consequence of this discordance in junctional morphology, of course, is that the circulations end-up in parallel, rather than in series, with the systemic venous return being channelled back to the body, and the pulmonary venous blood returning to the lungs (Fig. 1). In the absence of associated malformations, such as atrial or ventricular septal defects, or patency of the arterial duct, this morphological arrangement is incompatible with survival. Indeed, prior to the modern era, most infants born with this combination died in the first months of life.1,2 Therapeutic innovations, notably the introduction of balloon atrial septostomy,3 have changed all that. Now, coupled with surgical advances, initially atrial redirection,4,5 and then the arterial switch procedure,6 most neonates born with the malformation can anticipate a lengthy and good quality of life. Although there is now consensus concerning the clinical management of these segmental combinations, the best way of describing the morphological arrangement has been, and remains, fraught with difficulty.
A uniform surgical technique for transfer of both simple and complex patterns of the coronary arteries during the arterial switch procedure
Authors: Lacour-Gayet Francois , Anderson Robert H.
Published: September 2005

The arterial switch operation1 has now become the surgical treatment of choice for those patients born with transposition, specifically the combination of concordant atrioventricular and discordant ventriculo-arterial connections. For those working in experienced centres, the operation is now a stable and well-controlled procedure. The gathering of the necessary experience to achieve such control proceeds through two different stages. The first is the familiarity gained during the surgical transfer of the coronary arteries in those patients with the usual anatomic pattern. The second step is gain the expertise so as to cope with the more complex arrangements, in which the major coronary arteries have not only an unusual origin from the aortic sinuses, but also an unexpected epicardial course relative to the arterial pedicle. There can still be a steep learning curve as the surgeon corrects those patients with the more complex arrangements. In this review, we discuss a simplified but uniform technique for surgical transfer that permits relocation of the coronary arteries irrespective of their sinusal origin or their epicardial course. The technique has been used for more than 15 years in Hopital Marie Lannelongue in Paris,2–5 and proved its worth during the initial experience of the Senior Author (FLG) in two new centres, namely the Universitat Krankenhaus Eppendorf, Hamburg, and the Children's Hospital, Denver.
Surgical management of transposition with ventricular septal defect and obstruction to the left ventricular outflow tract
Authors: Morell Victor O. , Jacobs Jeffrey P. , Quintessenza James A.
Published: September 2005

The arterial switch operation has become the preferred surgical procedure for the management of simple and complex transposition, defined on the basis of concordant atrioventricular but discordant ventriculo-arterial connections, with excellent results over the short-term, and thus far over the long-term. When transposition is associated with a ventricular septal defect, and there is additional obstruction within the left ventricular outflow tract, the complexity of the surgical repair is increased, and the surgical options are not as attractive.
Challenges facing the child, adolescent, and young adult after the arterial switch operation
Authors: Mussatto Kathleen , Wernovsky Gil
Published: September 2005

The arterial switch operation is now recognized as the procedure of choice for treatment of infants and children born with the combination of concordant atrioventricular and discordant ventriculo-arterial connections, usually known simply as transposition. Although the Mustard and Senning atrial switch procedures achieved widespread acceptance and success, the accumulating observations at mid- to late follow-up of, first, the increasing frequency of arrhythmias and sudden death, second, late right ventricular dysfunction and severe tricuspid regurgitation and, third, high operative mortality in such patients with ventricular septal defects, have led to the worldwide use of the arterial switch operation for both simple and complex forms of transposition.1
Techniques for repairing the aortic and truncal valves
Authors: Backer Carl L.
Published: September 2005

There are now many surgical alternatives available for repairing the aortic valve, depending on whether the primary problem is one of stenosis or insufficiency. Patients with insufficiency of the common truncal valve have a unique anatomic substrate, which in some cases allows an innovative strategy of repair not available for the typical patient with a diseased aortic valve. Surgeons should be aware that there are a large number of techniques described for repair of the aortic valve. Some of these are shown in Table 1. For repair of the truncal valve, in contrast, fewer techniques have been described. As shown in Table 2, they are significantly different than those available for repair of the aortic valve.
Laboratory studies regarding regional low-flow perfusion for neonatal cardiac surgery
Authors: DeCampli William M.
Published: September 2005

As the overall mortality declines following repair of complex congenital cardiac malformations, attention has focused on reducing the lasting morbidity of these interventions, particularly the observed neurodevelopmental deficiencies. Both cardiopulmonary bypass and deep hypothermic circulatory arrest produce transient alterations in cerebral hemodynamics and metabolism. In studies performed in animals, deep hypothermic circulatory arrest, as compared to cardiopulmonary bypass alone, has been shown to produce excess injury to, and death of, neuronal and glial cells.1 In neonates, deep hypothermic circulatory arrest of greater duration than one hour is a risk factor for early post-operative seizures, and for subsequent neurodevelopmental deficits.2 The Boston Circulatory Arrest Study suggests that, at follow-up of eight years, infants subjected to greater than 41 minutes of deep hypothermic circulatory arrest had excess deficits in full-scale, verbal and performance intelligence quotient, the Mayo apraxia test, and grooved pegboard testing.3 The independent adverse effects of deep hypothermic circulatory arrest have encouraged clinicians to develop the alternative technique of intermittent global perfusion, or continuous regional perfusion at low flow perfusion, in an attempt to reduce the degree of injury to the central nervous system.4–7
Optimizing response of the neonate and infant to cardiopulmonary bypass
Authors: Ungerleider Ross M.
Published: September 2005

The evolution of cardiac surgery has led to increasing emphasis on complete repair of congenital heart defects early in life, nowadays increasingly performed in neonates or small infants. Good results have been achieved because of innovative techniques permitting reconstruction of normal anatomy, and restoration of normal physiology, before either the heart or the patient undergo deleterious adaptation to the congenitally abnormal physiology. Despite the ability surgically to correct complex defects in such small patients, limitations in outcome are sometimes encountered related to the systems necessary for repair. In particular, exposure to cardiopulmonary bypass may present the greatest challenge for these tiny patients.
Detection and prevention of neurologic injury in the intensive care unit
Authors: Hoffman George M.
Published: September 2005

Survivors of repairs of complex congenital cardiac malformations in infancy have an increased risk of permanent abnormalities in motor, cognitive, expressive, and behavioral functioning. These functional deficits are expressions of complex interactions of environment, including prolonged hospitalization and conditioned child–parental behaviours, alterations of social environment, the effects of physical limitations, biological influences including genetic determinants, prenatal injury, and acquired reversible and irreversible neuronal injury.1,2 The magnitude of the problem is large, with incidence dependent upon the measures used for assessment. Overt postoperative neurologic signs have been recorded in up to one-tenth of postoperative infants and children, with double that rate found in those with abnormalities of the aortic arch.3 A decreased potential for development, based upon parent-sibling models, has been estimated to occur in one-third of survivors.4,5 Evidence of injury is provided by magnetic resonance imaging in up to one-third of patients preoperatively, and between half and nine-tenths postoperatively, although most of these early postoperative changes will disappear.5 Although recent changes in perioperative management are likely to reduce such neurologic injury, their significance remains high.