Cardiac computed tomography post-transcatheter aortic valve replacement.

Transcatheter aortic valve replacement (TAVR) is performed to treat aortic stenosis and is increasingly being utilised in the low-to-intermediate-risk population. Currently, attention has shifted towards long-term outcomes, complications and lifelong maintenance of the bioprosthesis. Some patients with TAVR in-situ may develop significant coronary artery disease over time requiring invasive coronary angiography, which may be problematic with the TAVR bioprosthesis in close proximity to the coronary ostia. In addition, younger patients may require a second transcatheter heart valve (THV) to 'replace' their in-situ THV because of gradual structural valve degeneration. Implantation of a second THV carries a risk of coronary obstruction, thereby requiring comprehensive pre-procedural planning. Unlike in the pre-TAVR period, cardiac CT angiography in the post-TAVR period is not well established. However, post-TAVR cardiac CT is being increasingly utilised to evaluate mechanisms for structural valve degeneration and complications, including leaflet thrombosis. Post-TAVR CT is also expected to have a significant role in risk-stratifying and planning future invasive procedures including coronary angiography and valve-in-valve interventions. Overall, there is emerging evidence for post-TAVR CT to be eventually incorporated into long-term TAVR monitoring and lifelong planning.

Early SGLT2 inhibitor use is associated with improved left atrial strain following acute coronary syndrome.

AIM: Left atrial (LA) strain, a novel marker of LA function, reliably predicts diastolic dysfunction. SGLT2 inhibitors improve heart failure outcomes, but limited data exists regarding their use in the immediate aftermath of acute coronary syndrome (ACS). We studied the effect of empagliflozin on LA strain in patients with type 2 diabetes (T2D) and ACS. METHODS: Patients with ACS and T2D were identified and empagliflozin was initiated in eligible patients prior to discharge. Patients not initiated on empagliflozin were analysed as a comparator group. A blinded investigator assessed LA strain using baseline and 3-6 month follow-up echocardiograms. RESULTS: Forty-four participants (n = 22 each group) were included. Baseline characteristics and LA strain were similar in the two groups. LA reservoir, conduit and contractile strain increased in empagliflozin group (28.0 ± 8.4% to 34.6 ± 12.2% p < 0.001, 14.5 ± 5.4% to 16.7 ± 7.0% p = 0.034, 13.5 ± 5.2% to 17.9 ± 7.2% p = 0.005, respectively) but remained unchanged in comparison group (29.2 ± 6.7% to 28.8 ± 7.0%, 12.8 ± 4.2% to 13.3 ± 4.7%, 16.7 ± 5.3% to 15.5 ± 4.5%, respectively, p = NS). The difference in change between groups was significant for LA reservoir (p = 0.003) and contractile strain (p = 0.005). CONCLUSION: In patients with ACS and T2D, addition of empagliflozin to standard ACS therapy prior to discharge is associated with improved LA function.

Medical Therapy to Prevent or Slow Progression of Aortic Stenosis: Current Evidence and Future Directions.

Degenerative aortic stenosis is a growing clinical problem owing to the high incidence in an aging population and its significant morbidity and mortality. Currently, aortic valve replacement remains the only treatment. Despite promising observational data, pharmacological management to slow or halt progression of aortic stenosis has remained elusive. Nevertheless, with a greater understanding of the mechanisms which underpin aortic stenosis, research has begun to explore novel treatment strategies. This review will explore the historical agents used to manage aortic stenosis and the emerging agents that are currently under investigation.

An acoustofluidic scanning nanoscope using enhanced image stacking and processing.

Nanoscale optical resolution with a large field of view is a critical feature for many research and industry areas, such as semiconductor fabrication, biomedical imaging, and nanoscale material identification. Several scanning microscopes have been developed to resolve the inverse relationship between the resolution and field of view; however, those scanning microscopes still rely upon fluorescence labeling and complex optical systems. To overcome these limitations, we developed a dual-camera acoustofluidic nanoscope with a seamless image merging algorithm (alpha-blending process). This design allows us to precisely image both the sample and the microspheres simultaneously and accurately track the particle path and location. Therefore, the number of images required to capture the entire field of view (200 × 200 µm) by using our acoustofluidic scanning nanoscope is reduced by 55-fold compared with previous designs. Moreover, the image quality is also greatly improved by applying an alpha-blending imaging technique, which is critical for accurately depicting and identifying nanoscale objects or processes. This dual-camera acoustofluidic nanoscope paves the way for enhanced nanoimaging with high resolution and a large field of view.

How Does Emergency Department Crowding Affect Medical Student Test Scores and Clerkship Evaluations?

INTRODUCTION: The effect of emergency department (ED) crowding has been recognized as a concern for more than 20 years; its effect on productivity, medical errors, and patient satisfaction has been studied extensively. Little research has reviewed the effect of ED crowding on medical education. Prior studies that have considered this effect have shown no correlation between ED crowding and resident perception of quality of medical education. OBJECTIVE: To determine whether ED crowding, as measured by the National ED Overcrowding Scale (NEDOCS) score, has a quantifiable effect on medical student objective and subjective experiences during emergency medicine (EM) clerkship rotations. METHODS: We collected end-of-rotation examinations and medical student evaluations for 21 EM rotation blocks between July 2010 and May 2012, with a total of 211 students. NEDOCS scores were calculated for each corresponding period. Weighted regression analyses examined the correlation between components of the medical student evaluation, student test scores, and the NEDOCS score for each period. RESULTS: When all 21 rotations are included in the analysis, NEDOCS scores showed a negative correlation with medical student tests scores (regression coefficient= -0.16, p=0.04) and three elements of the rotation evaluation (attending teaching, communication, and systems-based practice; p<0.05). We excluded an outlying NEDOCS score from the analysis and obtained similar results. When the data were controlled for effect of month of the year, only student test score remained significantly correlated with NEDOCS score (p=0.011). No part of the medical student rotation evaluation attained significant correlation with the NEDOCS score (p≥0.34 in all cases). CONCLUSION: ED overcrowding does demonstrate a small but negative association with medical student performance on end-of-rotation examinations. Additional studies are recommended to further evaluate this effect.

Roles of E. coli double-strand-break-repair proteins in stress-induced mutation.

Special mechanisms of mutation are induced during growth-limiting stress and can generate adaptive mutations that permit growth. These mechanisms may provide improved models for mutagenesis in antibiotic resistance, evolution of pathogens, cancer progression and chemotherapy resistance. Stress-induced reversion of an Escherichia coli episomal lac frameshift allele specifically requires DNA double-strand-break-repair (DSBR) proteins, the SOS DNA-damage response and its error-prone DNA polymerase, DinB. We distinguished two possible roles for the DSBR proteins. Each might act solely upstream of SOS, to create single-strand DNA that induces SOS. This could upregulate DinB and enhance mutation globally. Or any or all of them might function other than or in addition to SOS promotion, for example, directly in error-prone DSBR. We report that in cells with SOS genes derepressed constitutively, RecA, RuvA, RuvB, RuvC, RecF, and TraI remain required for stress-induced mutation, demonstrating that these proteins act other than via SOS induction. RecA and TraI also act by promoting SOS. These and additional results with hyper-mutating recD and recG mutants support roles for these proteins via error-prone DSBR. Such mechanisms could localize stress-induced mutagenesis to small genomic regions, a potentially important strategy for adaptive evolution, both for reducing additional deleterious mutations in rare adaptive mutants and for concerted evolution of genes.