Quantification of left and right atrial kinetic energy using four-dimensional intracardiac magnetic resonance imaging flow measurements

Kinetic energy (KE) of atrial blood has been postulated as a possible contributor to ventricular filling. Therefore, we aimed to quantify the left and right atrial blood KE using cardiac magnetic resonance (CMR). Fifteen healthy volunteers underwent CMR at 3T, including a four-dimensional phase contrast flow sequence. Mean left atrial (LA) KE was lower than right atrial (RA) KE (1.1±0.1 mJ vs 1.7±0.1 mJ, P<0.01). Three KE peaks were seen in both atria; one in ventricular systole, one during early ventricular diastole, and one during atrial contraction. The systolic LA peak was significantly smaller than the RA peak (P<0.001), and the early diastolic LA peak was larger than the RA peak (P<0.05). Rotational flow contained 46 ± 7% of total KE, and conserved energy better than non-rotational flow did. The KE increase in early diastole was higher in the LA (P<0.001). Systolic KE correlated with the combination of atrial volume and systolic velocity of the atrioventricular plane displacement (R2=0.57 for LA and R2=0.64 for RA). Early diastolic KE of the LA correlated with LV mass (R2=0.28), however no such correlation was found in the right heart. This suggests that LA KE increases during early ventricular diastole due to LV elastic recoil, indicating that LV filling is dependent on diastolic suction. RV relaxation does not seem to contribute to atrial KE. Instead, atrial KE generated during ventricular systole may be conserved in a hydraulic "flywheel" and transferred to the RV through helical flow, which may contribute to RV filling

Clinical applications of intra-cardiac four-dimensional flow cardiovascular magnetic resonance: A systematic review

Background: Four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) is an emerging non-invasive imaging technology used to visualise and quantify intra-cardiac blood flow. The aim of this systematic review is to assess the literature on the current clinical applications of intra-cardiac 4D flow CMR. Methods: A systematic review was conducted to evaluate the literature on the intra-cardiac clinical applications of 4D flow CMR. Structured searches were carried out on Medline, EMBASE and the Cochrane Library in October 2016. A modified Critical Skills Appraisal Programme (CASP) tool was used to objectively assess and score the included studies. Studies were categorised as ‘highly clinically applicable’ for scores of 67–100%, ‘potentially clinically applicable’ for 34–66% and ‘less clinically applicable’ for 0–33%. Results: Of the 1608 articles screened, 44 studies met eligibility for systematic review. The included literature consisted of 22 (50%) mechanistic studies, 18 (40.9%) pilot studies and 4 (9.1%) diagnostic studies. Based on the modified CASP tool, 27 (62%) studies were ‘highly clinically applicable’, 9 (20%) were ‘potentially clinically applicable’ and 8 (18%) were ‘less clinically applicable’. Conclusions: There are many proposed methods for using 4D flow CMR to quantify intra-cardiac flow. The evidence base is mainly mechanistic, featuring single-centred designs. Larger, multi-centre studies are required to validate the proposed techniques and investigate the clinical advantages that 4D flow CMR offers over standard practices

Leaching of Hazardous Substances from Concrete Constituents and Painted Wood Panels

At a time of increased concern about environmental issues in the building sector, it is essential to know the environmental performance of different building materials. Knowledge of the possible release of hazardous substances in building materials is scarce, and these aspects have often been neglected in environmental assessment methods. This research has studied the content and leaching behaviour of hazardous substances in concrete constituents and paints on wooden facades. The leaching tests for both materials were diffusion tests to study the time-dependent leaching, and availability tests to find the fraction that is available for leaching in the long term. The first part presents studies of concrete with additives of admixtures and industrial by-products such as slag and fly ash. The complex leaching process is studied both theoretically and in laboratory experiments. There was no significant difference in leaching of metals between the concretes with by-products and concrete with Portland cement. Each of the studied metals showed a unique leaching pattern. A new availability test instead of commonly used standard tests is proposed, when the purpose is to estimate the leaching during the service life of monolithic concrete. A different view of the leaching process and its changes over time is also presented. The leaching of concrete with admixtures containing thiocyanate, resin acids or nonylphenol ethoxylate was also studied, because of their toxic character. Both the diffusion test and the availability test showed relatively high leached fractions. Two thirds of the total amount were leached from crushed concrete containing thiocyanate. Not only nonylphenol ethoxylate but also nonylphenol was found in the leachate water a more toxic, genotoxic and low-degradable substance. The results imply risks of using unspecified, crushed concrete in landfills. Part Two of this thesis presents leaching studies of biocides in wooden fa\ub8ade paint. Painted wood panels is a common fa\ub8ade cladding in Sweden, and microbiological growth in the paint is hampered by means of biocides. Panels in the field were exposed to natural rain, and both the run-off water and the surface analysis showed that considerable leaching from paint might occur Time-dependent leaching tests in laboratory environment gave lower leached amounts and a different behaviour than in the field study, which could be due to different climatic conditions and paint systems. A more aggressive, long-term availability test yielded profiles of the paint film with a non-steady-state condition, and clear signs of leaching about 30-50% when comparing profiles before and after leaching. The profiles reveal that the biocide IPBC migrates not only towards the surface, but also into the wood