Per Christensen

A comparison of single-lead atrial pacing with dual-chamber pacing in sick sinus syndrome

AIMS In patients with sick sinus syndrome, bradycardia can be treated with a single-lead pacemaker or a dual-chamber pacemaker. Previous trials have revealed that pacing modes preserving atrio-ventricular synchrony are superior to single-lead ventricular pacing, but it remains unclear if there is any difference between single-lead atrial pacing (AAIR) and dual-chamber pacing (DDDR). METHODS AND RESULTS We randomly assigned 1415 patients referred for first pacemaker implantation to AAIR (n = 707) or DDDR (n = 708) pacing and followed them for a mean of 5.4 ± 2.6 years. The primary outcome was death from any cause. Secondary outcomes included paroxysmal and chronic atrial fibrillation, stroke, heart failure, and need for pacemaker reoperation. In the AAIR group, 209 patients (29.6%) died during follow-up vs. 193 patients (27.3%) in the DDDR group, hazard ratio (HR) 1.06, 95% confidence interval (CI) 0.88-1.29, P = 0.53. Paroxysmal atrial fibrillation was observed in 201 patients (28.4%) in the AAIR group vs. 163 patients (23.0%) in the DDDR group, HR 1.27, 95% CI 1.03-1.56, P = 0.024. A total of 240 patients underwent one or more pacemaker reoperations during follow-up, 156 (22.1%) in the AAIR group vs. 84 (11.9%) in the DDDR group (HR 1.99, 95% CI 1.53-2.59, P < 0.001). The incidence of chronic atrial fibrillation, stroke, and heart failure did not differ between treatment groups. CONCLUSION In patients with sick sinus syndrome, there is no statistically significant difference in death from any cause between AAIR pacing and DDDR pacing. AAIR pacing is associated with a higher incidence of paroxysmal atrial fibrillation and a two-fold increased risk of pacemaker reoperation. These findings support the routine use of DDDR pacing in these patients. CLINICAL TRIAL REGISTRATION URL http://www.clinicaltrials.gov. Unique identifier: NCT00236158.

Problem-oriented and project-based learning (POPBL) as an innovative learning strategy for sustainable development in engineering education

Abstract In a world where systems are increasingly larger, where their boundaries are often difficult to identify, and where societal rather than technical issues play increasingly bigger roles, problems cannot be solved by applying a technical solution alone. It thus becomes important for engineers to be skilled not only in terms of their particular technical field but also their ability to identify non-technical aspects of problems, the interaction between these aspects and possible solutions. Introducing and integrating these aspects into engineering education is certainly not an easy task and requires innovative approaches. In this article, focus is placed on the so-called Aalborg Model, a problem-oriented and project-based learning paradigm utilised at Aalborg University (Denmark), and the mutual benefits that this particular learning strategy provides for students, faculty and communities. The article discusses the concept of sustainable development; accounts for the general capabilities of engineering education graduates, and discusses the integration of non-technical issues into various environmental engineering curricula. On the basis of this discussion, it underlines the importance of applying a problem-oriented rather than a subject-oriented approach in order to create a balance between problem occurrence (or identification) and innovative problem solving. We conclude that, in order for engineers to be able to handle sustainability-related problems, their education needs to allow for interplay, mix and diversity; aspects that a problem-oriented and project-based learning approach will involve.

Efficacy and safety of intravenously administered dofetilide in acute termination of atrial fibrillation and flutter: A multicenter, randomized, double-blind, placebo-controlled trial

Background This study was designed to assess the efficacy and safety of intravenous dofetilide in acute termination of atrial fibrillation (AF) and flutter (AFL). Dofetilide, an investigational class III antiarrhythmic agent, selectively inhibits the rapid component of the delayed rectifier potassium current, thus prolonging the effective refractory period and duration of the action potential. Dofetilide can be administered intravenously and has a rapid onset of electrophysiologic action. Methods and Results Ninety-six patients with AF (n = 79) or AFL (n = 17) with a median arrhythmia duration of 62 days (range 1 to 180) were randomized to placebo (n = 30) or 8 μg/kg IV dofetilide (n = 66) over 30 minutes. Conversion was defined as termination of the atrial arrhythmia within 3 hours from the start of infusion. The conversion rate was 30.3% after dofetilide and 3.3% after placebo (P < .006). Conversion rate was higher in AFL than in AF: 64% versus 24% (P = .012). In nonconverters, there was no statistically significant difference between the change in heart rate among the dofetilide-treated compared with the placebo-treated patients (P = .42). Torsade de pointes ventricular tachycardia developed in 2 patients (3%). In both patients, drug infusion was discontinued before the event because of prolongation of the QT interval. Conclusions Intravenous dofetilide is effective in acute termination of AF and AFL of medium duration, with a particularly high efficacy rate in AFL. A small but serious risk of proarrhythmia must be anticipated. (Am Heart J 1999;137:1062-9.)

Conflicting views of sustainability: The case of wind power and nature conservation in Denmark

Renewable energy has been prioritized in Danish energy policy since the early 1980s. This has led to the current situation where Denmark is one of the leading countries in the world in the field of wind energy utilization. The background for this success is a story about how a society can manage the development and diffusion of sustainable technologies so that they are simultaneously socially acceptable and environmentally benign. Consequently, this article describes the relationship between the organization of wind power and the protection of nature. The aim is to analyse which kinds of public planning and policy can promote wind power and nature protection in a situation where a conflict exists between these two issues. The discussion acknowledges that it has been a serious problem to balance these contrasting considerations. However, it also suggests that the problems seem solvable if technology development, the social organization relating to the use of the technology and proper planning are brought together to work in a spirit of local involvement.

Critical factors for EIA implementation: Literature review and research options

After decades of development, the gap between expectations of Environment Impact Assessments (EIA) and their practical performance remains significant. Research has been done to identify the critical factors for an effective implementation of EIA. However, this research, to a large extent, has not been cumulated and analysed comprehensively according to the stages of the EIA process. This paper contributes to the critical review of the literature on EIA implementation and effectiveness by cumulating mainly empirical findings in an implementation theoretical perspective. It focuses on the links between different critical factors and how they relate to different stages in the EIA and thus influence the decision making process. After reviewing 33 refereed journal articles published between 1999 and 2011, we identified 203 notions of critical factors. Of these, 102 related to different stages defined in our comprehensive EIA implementation model, and 101 were identified as general factors related to the whole EIA system. The number of notions of stage factors and general factors is thus about equal. An overlap between stage factors and general factors was found, which demonstrates that critical factors function differently in different cases. The function of the critical factors is complex and it is difficult to determine contingencies and causations. In the sources we examined, there is evidently an imbalance between in-depth empirical research and general knowledge, and the paper offers some suggestions for future research.

Sustainable Development: Assessing the Gap between Preaching and Practice at Aalborg University.

Purpose – This article aims to discuss the contradiction between signing an agreement to work for sustainable universities and the lack of practical commitment in one case, namely at Aalborg University (AAU). Focus is placed both on the Universitys core processes such as education, research and outreach; on the necessary inputs and outputs related to transport, food and operation, and maintenance of buildings, and on the universitys products counting published results of research and educated students and researchers. Design/methodology/approach – The study is based on a desk study of official university documents from the period 1990 to 2007, and a number of student reports that have focused on the sustainability or environmental merits of the University. Findings – Although adopting an environmental policy and signing the Copernicus Charter back in the early 1990s, AAU soon lost momentum. This was due to reasons defined as: the lack of commitment from top management, the missing acceptance from technical staff, and a narrow understanding of the universitys environmental impacts. Obviously, a model of the environmental impacts should not only take into account the environmental impacts related to the impacts occurring in the present, e.g. related to the running and maintenance of buildings and laboratories, but also integrate considerations about the impacts in the processes (education, research and outreach). Thereby, the model shall provide the basis for more sustainable products, such as students considering aspects of sustainability in the solutions and approaches they apply in their future careers. Research limitations/implications – This article forms the basis for future research identifying how universities can contribute to sustainable development in a more coherent way by implementing new policies and plans. The article takes its starting point in a general model of a universitys environmental impacts involving key processes at the university, the related inputs and outputs (emissions), and the transformation of intermediate products such as high school students and existing research results into products such as graduate students, PhDs, and new research results. Practical implications – The processes and the related inputs, outputs, intermediate products, and end‐products are analysed and discussed in order to illustrate the relevant environmental issues that need to be addressed by universities. Originality/value – The paper identifies a number of key issues of sustainability that universities need to address and offers inspiration to staff and students on how to push these agendas at their home universities.

Atrial fibrillation in patients with sick sinus syndrome: the association with PQ-interval and percentage of ventricular pacing

AIMS In the recently published DANPACE trial, incidence of atrial fibrillation (AF) was significantly higher with single-lead atrial (AAIR) pacing than with dual-chamber (DDDR) pacing. The present analysis aimed to evaluate the importance of baseline PQ-interval and percentage of ventricular pacing (VP) on AF. METHODS AND RESULTS We analysed data on AF during follow-up in 1415 patients included in the DANPACE trial. In a subgroup of 650 patients with DDDR pacemaker, we studied whether %VP, baseline PQ-interval, and programmed atrio-ventricular interval (AVI) was associated with AF burden measured as time in mode-switch (MS) detected by the pacemaker. In the entire DANPACE study population, the incidence of AF was significantly higher in patients with baseline PQ-interval >180 ms (P< 0.001). Among 650 patients with DDDR pacemaker, telemetry data were available for 1.337 ± 786 days, %VP was 66 ± 33%, AF was detected at planned follow-up in 160 patients (24.6%), MS occurred in 422 patients (64.9%), and AF burden was marginally higher with baseline PQ-interval >180 ms (P= 0.028). No significant association was detected between %VP and %MS (Spearmans ρ 0.056, P= 0.154). %MS was not different between minimal-paced programmed AVI ≤ 100 and >100 ms (median value), respectively (P= 0.60). CONCLUSIONS The present study indicates that a longer baseline PQ-interval is associated with an increased risk of AF in patients with sick sinus syndrome. Atrial fibrillation burden is not associated with the percentage of VP or the length of the programmed AVI.

EIA as Regulation: Does it Work?

Since its introduction into Danish planning in 1989, Environmental Impact Assessment (EIA) has been widely discussed. At the centre of the debate the question has been whether EIA has actually offered anything new and there has been a great deal of scepticism about the efficacy of the instrument. Although, in principle EIA offers a holistic and proactive methodology, it does not seem to lead to a more holistic and proactive regulation which covers more ground than traditional planning and environmental regulation. In an evaluation of Danish experiences, this study has looked more closely at the effects of EIA. Three types of effects on projects have been examined: changes occurring prior to the formal application; changes during the EIA process; and the mitigation measures that are demanded of projects. The general conclusion is that EIA does generate a significant number of changes to projects. In approximately half of the cases studied, modifications are made prior to the formal application. During the formal EIA process, modifications were made in more than 90% of the cases. However, most of these could be considered as minor. EIA is characterized by being based upon a broad concept of the environment. It was found that a progressive narrowing of the concept of environment takes place during the course of the EIA process.

Energy production, nutrient recovery and greenhouse gas emission potentials from integrated pig manure management systems

Improper management of pig manure has resulted in environmental problems such as surface water eutrophication, ground water pollution, and greenhouse gas emissions. This study develops and compares 14 alternative manure management scenarios aiming at energy and nutrient extraction. The scenarios based on combinations of thermal pretreatment, anaerobic digestion, anaerobic co-digestion, liquid/solid separation, drying, incineration, and thermal gasification were compared with respect to their energy, nutrient and greenhouse gas balances. Both sole pig manure and pig manure mixed with other types of waste materials were considered. Data for the analyses were obtained from existing waste treatment facilities, experimental plants, laboratory measurements and literature. The assessment reveals that incineration combined with liquid/solid separation and drying of the solids is a promising management option yielding a high potential energy utilization rate and greenhouse gas savings. If maximum electricity production is desired, anaerobic digestion is advantageous as the biogas can be converted to electricity at high efficiency in a gas engine while allowing production of heat for operation of the digestion process. In conclusion, this study shows that the choice of technology has a strong influence on energy, nutrient and greenhouse gas balances. Thus, to get the most reliable results, it is important to consider the most representative (and up-to-date) technology combined with data representing the area or region in question.

Assessing the land use implications of biodiesel use from an LCA perspective

The land use required in order to meet the increasing demand for biodiesel has significant impacts. New methodological developments within environmental life cycle assessment (LCA) establish a cause–effect relationship between the demand for biodiesel and its impacts on biodiversity. The objective of this article is to assess and compare the impacts of rapeseed oil (RSO) production in the EU and palm oil (PO) production in Southeast Asia. The functional unit of the LCA is 20.8 Mtoe (million tons oil equivalents) biodiesel equalling the EU25 goals for biodiesel in 2020. Land occupation and transformation are quantified for the two alternative vegetable oils, and losses throughout the product chain from cultivation over crushing to refining are inventoried. Market mechanisms and land which is indirectly affected by product substitutions from co-products are included in the modelling. Land occupation and transformation are evaluated by the use of life cycle impact assessment (LCIA) models on land use and biodiversity. Three basic scenarios are evaluated: (1) RSO-based biodiesel is produced from rapeseed grown on fields which were previously grown by other crops (barley, BL) – the displaced BL is imported from abroad; (2) RSO-based biodiesel is produced from rapeseed grown on former set-aside land in the EU; and (3) PO-based biodiesel produced in Southeast Asia is imported to the EU. It is concluded that the new EU policies on using set-aside land for energy crops cannot cover the European demand for biodiesel and crops must thus be imported from outside the EU. This means that land use outside the EU is affected. The modelling shows that the use of PO affects the land use in Malaysia or Indonesia and that Canadian land use for BL cultivation is affected when rapeseed is produced in the EU. The impacts on land use and biodiversity are presented for all three scenarios. Finally, it is discussed how an LCA perspective like the one applied here can contribute to the assessment of environmental impacts within land use science.