Effective Tuning of Ketocyanine Derivatives through Acceptor Substitution.

A series of ketocyanine derivatives possessing bis(diarylamino)fluorenyl donors and variable acceptors installed at the bridging carbon atom were synthesized to investigate how the electronic structure of the dye can be systemically tuned through stabilization of the cyanine-like character of the donor by increasing the acceptor strength. Analysis of the (1) H NMR spectra indicates that the "charge-separated" species dominates in these dyes, given that carbons possessing a positive or negative charge in the resonance structures of this state purposefully shift downfield or upfield, respectively, depending on the strength of the acceptor moiety. In DAA-Fl-PI, the acceptor strength and the gain of acceptor aromaticity indicates a predisposition of the separated state, indicated by asymmetry in the (1) H NMR spectrum, as well as uneven distribution of the HOMO on the fluorenyl donor.

A Quality Improvement Initiative for Echocardiogram Ordering Patterns in an Academic Hospital.

Background Appropriate Use Criteria (AUC) for echocardiography are a useful tool to deliver quality healthcare. Our quality-based interventional study was designed to assess the trends in appropriate utilization rates for echocardiography in our institution and improve adherence to the AUC criteria for transthoracic echocardiograms (TTE). Methodology A prospective, time series analysis was conducted at the Upstate University Hospital for the months of July 2019 and August 2020. A chart analysis was performed on 620 consecutive inpatients who underwent TTE for the month of July 2019. We assessed the trends of the appropriate ordering of TTEs. We then updated our order form incorporating the 42 most common appropriate indications. A post-intervention chart analysis was performed on all inpatient TTEs ordered for the month of August 2020 (n = 410). The appropriateness of the TTE for the entire group was determined based on the true indication per chart review. The primary outcome was the proportion of appropriate and inappropriate TTEs ordered. Secondary outcomes included assessing for concordance between the indication on the order requisition form and by chart review. A p-value <0.05 was considered significant. Results Using the 2011 AUC for the entire group, 81% of the pre-intervention TTEs and 79.5% of the post-intervention TTEs were appropriate (p = 0.55). There was a statistically significant reduction in the number of discordant TTE orders before and after the intervention (p < 0.01). In addition, we noted increased appropriateness of TTEs in the concordant group both pre and post-intervention. Conclusions Our study demonstrates a significant increase in the concordance between the TTE order sheet and actual indication per chart review with the intervention. This can translate into improved scanning and physician reading quality and time, thereby increasing focus on areas of interest according to the true indication. There was no significant increase in the appropriate TTEs ordered.

Acute ST-Segment Elevation Myocardial Infarction as a Rare Postoperative Complication of Biventricular Implantable Cardioverter-Defibrillator Placement.

We present a rare case of an 84-year-old woman who suffered an acute ST-segment elevation myocardial infarction as a postoperative complication of biventricular implantable cardioverter-defibrillator placement, caused by the left ventricular lead impinging onto the second obtuse marginal artery. (Level of Difficulty: Intermediate.).

Learning a sparse code for temporal sequences using STDP and sequence compression.

A spiking neural network that learns temporal sequences is described. A sparse code in which individual neurons represent sequences and subsequences enables multiple sequences to be stored without interference. The network is founded on a model of sequence compression in the hippocampus that is robust to variation in sequence element duration and well suited to learn sequences through spike-timing dependent plasticity (STDP). Three additions to the sequence compression model underlie the sparse representation: synapses connecting the neurons of the network that are subject to STDP, a competitive plasticity rule so that neurons specialize to individual sequences, and neural depolarization after spiking so that neurons have a memory. The response to new sequence elements is determined by the neurons that have responded to the previous subsequence, according to the competitively learned synaptic connections. Numerical simulations show that the model can learn sets of intersecting sequences, presented with widely differing frequencies, with elements of varying duration.

Identification of a High-risk Subgroup With Malignant Mitral Valve Prolapse Who Are Predisposed to Sudden Cardiac Death: A Review.

Mitral valve prolapse (MVP) affects approximately 170 million people worldwide; however, phenotypically, there is a wide variety of heterogeneity. In particular subsets, the incidence of sudden cardiac death is calculated to be 998 per 100,000 person-years, which is significantly increased when compared with the general population of MVP patients. Individuals with high-risk features have been identified as young females with bileaflet MVP and electrocardiogram findings of frequent complex ectopy, ST-T wave changes, and inferior T wave inversions. Supplemental imaging modalities in this subgroup demonstrate redundant leaflets and chordae on 2-dimensional transthoracic echocardiography along with varying severity of mitral annular disjunction. Detailed morphologic assessment by 3-dimensional echocardiography provides a quantitative assessment of annular disjunction along with left ventricular longitudinal and basal circumferential strain patterns. Late gadolinium enhancement on cardiac magnetic resonance imaging identifies diffuse and isolated left ventricle fibrosis involving the fascicles and papillary muscles, which has been visualized in isolation during autopsy. Findings of this review propose that sudden cardiac death as a result of malignant arrhythmias arises from automaticity, complex ectopy, and reentry at the level of the fascicles and papillary muscles. The repetitive mechanical stress provides a nidus for the development of both micro- and macrofibrosis easily identified by late gadolinium enhancement on cardiac magnetic resonance imaging. Escalation to electrophysiology studies and early intervention could provide new targeted lifesaving therapies.

Spiking neuron model for temporal sequence recognition.

A biologically inspired neuronal network that stores and recognizes temporal sequences of symbols is described. Each symbol is represented by excitatory input to distinct groups of neurons (symbol pools). Unambiguous storage of multiple sequences with common subsequences is ensured by partitioning each symbol pool into subpools that respond only when the current symbol has been preceded by a particular sequence of symbols. We describe synaptic structure and neural dynamics that permit the selective activation of subpools by the correct sequence. Symbols may have varying durations of the order of hundreds of milliseconds. Physiologically plausible plasticity mechanisms operate on a time scale of tens of milliseconds; an interaction of the excitatory input with periodic global inhibition bridges this gap so that neural events representing successive symbols occur on this much faster timescale. The network is shown to store multiple overlapping sequences of events. It is robust to variation in symbol duration, it is scalable, and its performance degrades gracefully with perturbation of its parameters.

Constrictive pericarditis decades after aortic valve repair.

Constrictive pericarditis is rare after cardiac surgery, with a time to presentation ranging from 82 days to 204 months. We report a 75-year-old man who underwent aortic valve replacement and developed constrictive pericarditis 21 years later. He underwent a pericardiectomy with pericardial stripping, which confirmed constrictive pericarditis and improved his symptoms.

Right Coronary Artery Pseudoaneurysm With Hemopericardium: A Rare Complication of Percutaneous Coronary Intervention.

While percutaneous coronary intervention (PCI) is a commonly performed procedure, it still has many serious complications. Coronary artery pseudoaneurysms can form after PCI and can progress to cardiac tamponade. We report the case of an 80-year-old male who presented for an inferior wall ST elevation myocardial infarction, had drug-eluting stents placed to the right coronary artery (RCA), and subsequently suffered a RCA pseudoaneurysm with hemopericardium. He eventually underwent pseudoaneurysm repair with off pump coronary artery bypass graft. There is no established treatment protocol, and involvement of a multidisciplinary team improves outcomes.