Elevated high-sensitivity troponin does not indicate the presence of coronary artery disease in patients presenting with supraventricular tachycardia.

BACKGROUND: Patients with supraventricular tachycardia (SVT) and patients with coronary artery disease (CAD) often present with similar symptoms (chest pain, shortness of breath), similar electrocar¬diographic changes and elevated high-sensitivity troponin (Tn). It is not clear whether troponin reflects critical CAD or is elevated due to other causes in patients presenting with SVT. The aim of this study was to assess the role of elevated troponin in patients presenting with SVT. METHODS: Patients undergoing radiofrequency ablation (RFA) for SVT and simultaneous coronary an¬giography at the Heart Centre Lucerne, Switzerland between January 2010 and October 2014 were in¬cluded in this analysis. Significant CAD was defined as diameter-stenosis ≥ 75% in vessels > 2.0 mm. The level of Tn was compared between patients with the presence or absence of CAD on coronary angi¬ography. A Tn value of ≥ 0.014 µg/L was considered as elevated. RESULTS: During the study period a total of 473 patients underwent RFA for SVT. The study population consisted of 326 patients (69%, mean age 60 ± 12 years) who underwent invasive coronary angiogra¬phy during the same session. The prevalence of significant CAD was 14% (45/326 patients). The highest prevalence of CAD was found in patients with atrial flutter (35%, 18/45 patients). Tn was elevated in 83% (10/12 patients) with significant CAD and in 47% (26/55 patients) without CAD. CONCLUSIONS: The prevalence of CAD is low in patients with SVT, which questions the role of routine invasive coronary angiography during RFA. Tn measurement did not reliably exclude or confirm CAD in these patients.

Energy efficiency monitoring--which sensors are really needed?

Plant balancing of waste-to-energy plants is a key issue in determining plant performance and operating efficiency. Traditionally, plant efficiency is determined only during the acceptance test by the means of an ex-post energy balance. For continuous operation, energy efficiency is estimated on a monthly or yearly basis using the waste throughput and average lower heating value. At Afval Energie Bedrijf in Amsterdam efficiency has to be reported on a monthly basis. Measured data from 83 positions is required to obtain the efficiency of the Hoog Rendement Central block with an ex-post energy balance on a continuous basis. This study investigated the importance of the different sensors. Efficiency calculations were performed after discarding the less important measuring positions. The measured data was replaced by the design value in the calculation. The total average margin of error per year for the efficiency value was found to be only 0.1% when the 23 most significant (instead of 83) measuring points were used, whereas individual values may differ by less than 0.5%. Operators of plants with fewer sensors can monitor their efficiency continuously if they know the most important positions.

Physical activity behaviour in patients with metabolic syndrome.

STUDY/PRINCIPLES: Physical activity improves the clinical course of the metabolic syndrome and its risk factors. The aim of this study was to investigate the physical activity behaviour in patients with metabolic syndrome in regard to the recommendation of the Federal Offices of Public Health (BAG) and Sports (BASPO): "to exercise half an hour a day at a medium intensity." METHODS: 47 patients with metabolic syndrome were recruited from the Outpatient Department of the Division of Internal Medicine of the University Hospital Zurich. 24 patients were included and physical activity behaviour was assessed by using the International Physical Activity Questionnaires. RESULTS: All of the patients knew about the positive effect of physical activity on the course of the metabolic syndrome although 62% of the patients (n = 15) had no knowledge of the BAG/BASPO recommendations. 54% of the patients (n = 13) performed physical activity in accordance to the recommendation with or without knowing the recommendations. Most of the patients (n = 21, 87%) were motivated to improve their physical activity, but missing opportunities and instructions were important reasons for not being physically active. CONCLUSION: Patients with metabolic syndrome usually know about the positive effect of physical activity on the course of their disorder and are motivated to improve physical activity behaviour. However, the BAG/BASPO recommendations are not widely known and should therefore become more popular and better communicated particularly to patients with metabolic syndrome. Furthermore, patients have to be supported and instructed practically how to get physically active in accordance with their co-morbidities.

High efficient waste-to-energy in Amsterdam: getting ready for the next steps.

Waste-to-energy (WtE) plants are traditionally designed for clean and economical disposal of waste. Design for output on the other hand was the guideline when projecting the HRC (HoogRendement Centrale) block of Afval Energie Bedrijf Amsterdam. Since commissioning of the plant in 2007, operation has continuously improved. In December 2010, the block's running average subsidy efficiency for one year exceeded 30% for the first time. The plant can increase its efficiency even further by raising the steam temperature to 480°C. In addition, the plant throughput can be increased by 10% to reduce the total cost of ownership. In order to take these steps, good preparation is required in areas such as change in heat transfer in the boiler and the resulting higher temperature upstream of the super heaters. A solution was found in the form of combining measured data with a computational fluid dynamics (CFD) model. Suction and acoustic pyrometers are used to obtain a clear picture of the temperature distribution in the first boiler pass. With the help of the CFD model, the change in heat transfer and vertical temperature distribution was predicted. For the increased load, the temperature is increased by 100°C; this implies a higher heat transfer in the first and second boiler passes. Even though the new block was designed beyond state-of-the art in waste-to-energy technology, margins remain for pushing energy efficiency and economy even further.