Characteristics and outcomes of gastrointestinal bleeding in patients with continuous-flow left ventricular assist devices: A systematic review.

Gastrointestinal bleeding (GIB) is a common adverse event after continuous-flow left ventricular assist device (CF-LVAD) implantation. We sought to evaluate patterns of GIB development and related outcomes in CF-LVAD recipients. An electronic search was performed to identify all articles related to GIB in the setting of CF-LVAD implantation. A total of 34 studies involving 1087 patients were pooled for analysis. Mean patient age was 60 years (95% CI 57-64) and 24% (95% CI 21-28%) were female. The mean time from CF-LVAD implantation to the first GIB was 54 days (95% CI 24-84) with 40% (95% CI 34-45%) of patients having multiple episodes of GIB. Anemia was present in 75% (95% CI 41-93%) and the most common etiology of bleeding was arteriovenous malformations (36% [95% CI 24-50%]). The mean duration of follow-up was 14.6 months (95% CI 6.9-22.3) during which the all-cause mortality rate was 21% (95% CI 12-36%) and the mortality rate from GIB was 4% (95% CI 2-9%). Thromboembolic events occurred in 32% (95% CI 22-44%) of patients with an ischemic stroke rate of 16% (95% CI 3-51%) and a pump thrombosis rate of 8% (95%CI 3-22%). Heart transplantation was performed in 31% (95% CI 18-47%) of patients, after which 0% (95% CI 0-10%) experienced recurrent GIB. GIB is a major source of morbidity among CF-LVAD recipients. While death due to GIB is rare, cessation of anticoagulation during treatment increases the risk of subsequent thrombotic events. Heart transplant in these patients appears to reliably resolve the risk of future GIB.

Valvectomy versus replacement for the surgical treatment of infective tricuspid valve endocarditis: a systematic review and meta-analysis.

BACKGROUND: Optimal surgical treatment of infective tricuspid valve endocarditis in patients with intravenous drug use (IVDU) remains controversial. Tricuspid valvectomy has been proposed for infective tricuspid valve endocarditis in this patient population given the inherent social concerns. The aim of this systematic review and meta-analysis was to compare outcomes of valvectomy versus replacement for the surgical treatment of isolated infective tricuspid valve endocarditis. METHODS: An electronic search was performed to identify all relevant studies published. After assessment for inclusion and exclusion criteria, 16 original studies were pooled for systematic review and meta-analysis. RESULTS: There were a total of 752 patients with infective tricuspid valve endocarditis, of which 14% underwent valvectomy and 86% underwent replacement (mean follow-up 4.2 years, 95% CI, 1.9-6.4 years). The most common indications for surgical intervention were septic pulmonary embolism in the valvectomy group (74%, 95% CI, 28-95%) and persistent sepsis in the replacement group (62%, 95% CI, 31-86%). There were no differences in rates of stroke [valvectomy 4% (95% CI, 1-11%) vs. replacement 3% (95% CI, 1-16%), P=0.85] but there was increased likelihood of prolonged ventilation in those who underwent valvectomy [valvectomy 40% (95% CI, 30-51%) vs. replacement 26% (95% CI, 23-30%), P<0.01]. There were no differences in 30-day post-operative mortality [valvectomy 13% (95% CI, 5-30%) vs. replacement 7% (95% CI, 5-10%), P=0.21], post-operative right heart failure [valvectomy 27% (95% CI, 10-53%) vs. replacement 11% (95% CI, 5-25%), P=0.17] and recurrent endocarditis [valvectomy 7% (95% CI, 2-23%) vs. replacement 19% (95% CI, 12-28%), P=0.81]. Valvectomy had a higher rate of tricuspid valve reoperation [valvectomy 56% (95% CI, 15-90%) vs. initial replacement 14% (95% CI, 7-27%), P=0.06]. CONCLUSIONS: Tricuspid valvectomy is an acceptable initial therapy for infective tricuspid valve endocarditis in patients with IVDU, providing a bridge to identify those who will self-select as candidates for staged valve replacement.

Concomitant vs staged orthotopic liver transplant after cardiac surgical procedures.

BACKGROUND: In patients who require orthotopic liver transplant (OLT), cardiac surgery may be needed to optimize preoperative cardiac status for OLT. The aim of this systematic review was to evaluate patient characteristics and outcomes of those undergoing staged versus concomitant cardiac procedures with OLT. METHODS: An electronic search was performed to identify all case reports and series, from which patient-level data was extracted regarding cardiac procedures associated with OLT. After assessment for inclusion and exclusion criteria, 26 articles were pooled for systematic review. RESULTS: Overall, 49 patients were included in the analysis, of whom 12 (24%) underwent staged procedures and 37 (76%) underwent concomitant procedures. The median age was lower in the staged group [staged: 51 (IQR, 43.8-59.2) years vs. concomitant: 60 (IQR, 55.0-64.0) years, p = .02]. Other baseline characteristics were comparable between the two groups. For staged procedures, the median time between heart procedures and OLT was 2 (IQR, 1.0-3.5) months. The most commonly reported cardiac procedures were coronary artery bypass graft (CABG) [staged: 4/12 (33.3%) vs. concomitant: 21/37 (56.8%), p = .28], aortic valve replacement (AVR) [staged: 3/12 (25.0%) vs. concomitant: 19/37 (51.2%), p = .21], and transcatheter aortic valve replacement (TAVR) [staged: 4/12 (33.3%) vs. concomitant: 0/37 (0%), p = .002]. Regarding outcomes, there was a significantly shorter post-OLT hospital stay for those who had staged procedures versus those who had concomitant procedures [staged: 8 (IQR, 5-13) days vs. concomitant: 17 (IQR, 14-24) days, p = .007]. However, both groups had similar in-hospital mortality rates [staged: 1/12 (8.3%) vs. concomitant: 4/37 (10.8%), p = 1.0]. Overall survival stratified between the two groups was comparable. CONCLUSIONS: Patients who underwent the staged approach had a shorter post-transplant hospital stay, but comparable survival with respect to those who underwent concomitant cardiac procedures and OLT.

Inter-process relations in spatial language: Feedback and graded compatibility.

Mapping spatial expressions such as "behind the cup" to a spatial region requires two processes that have been largely explored independently: reference frame selection and spatial term assignment (Logan & Sadler, 1996). Reference frame selection carves a space into regions. Spatial term assignment evaluates these regions by determining the acceptability of the term for the given configuration. Here we present a systematic investigation of the relation and interplay of these two processes by asking whether (a) information from spatial term assignment feeds back to selection and (b) whether competition during selection is graded. In a series of simulation studies, we assess the performance of four computational models, each of which instantiates a unique combination of feedback (no feedback vs. feedback) and gradedness (all-or-none compatibility vs. graded compatibility). The results support two key observations about human spatial term use: First, reference frame selection and spatial term assignment proceed concurrently and in mutual interaction, with assignment information feeding back and influencing the selection process. Second, competition in reference frame selection is graded such that the strength of competition between different available reference frames increases continuously with decreasing similarity of the frames. As such, our work provides a new view on the components involved in spatial term use and their interplay, and suggests more broadly that the gradedness of competition may also be an important aspect of conflict and selection in other cognitive domains.

Temporary mechanical circulatory support after orthotopic heart transplantation: a single-centre experience.

OBJECTIVES: There are various strategies in the use of temporary mechanical circulatory support following orthotopic heart transplant (OHT). We sought to examine the outcomes following different temporary mechanical circulatory support strategies for acute graft failure. METHODS: Patients who received an OHT between 2001 and 2015 at a single institution were retrospectively reviewed. Patients were divided into 2 groups based on the need for temporary mechanical circulatory support (TMCS). RESULTS: A total of 9.9% (19 of 192) of patients required TMCS following OHT. There were no significant differences in the preoperative demographics between groups. Six patients (32%) required a biventricular assist device, 9 patients (47%) required a right ventricular assist device and 4 patients (21%) required a veno-arterial extracorporeal membrane oxygenator. Perioperative morbidity was comparable between all groups. Our entire TMCS cohort had 94.7% 30-day and 61.1% 1-year survival. When compared with the OHT patients with no TMCS (97.1% at 30 days and 92.8% at 1 year), survival was inferior in TMCS patients ( P = 0.01 at 30 days, P < 0.001 at 1 year, P < 0.001 overall). CONCLUSIONS: Acute graft failure requiring TMCS has inferior overall survival. Larger, multi-institutional studies are needed to further elucidate these differences and identify the best TMCS mode.

Mechanisms of Reference Frame Selection in Spatial Term Use: Computational and Empirical Studies.

Previous studies have shown that multiple reference frames are available and compete for selection during the use of spatial terms such as "above." However, the mechanisms that underlie the selection process are poorly understood. In the current paper we present two experiments and a comparison of three computational models of selection to shed further light on the nature of reference frame selection. The three models are drawn from different areas of human cognition, and we assess whether they may be applied to a reference frame selection by examining their ability to account for both existing and new empirical data comprising acceptance rates, response times, and response time distributions. These three models are the competitive shunting model (Schultheis, ), the leaky competing accumulator (LCA) model (Usher & McClelland, ), and a lexical selection model (Howard, Nickels, Coltheart, & Cole-Virtue, ). Model simulations show that only the LCA model satisfactorily accounts for the empirical observations. The key properties of this model that seem to drive its success are its bounded linear activation function, its number and type of processing stages, and its use of decay. Uncovering these critical properties has important implications for our understanding not only of spatial term use, in particular, but also of conflict and selection in human cognition more generally.

Determinants of attentional modulation near the hands.

A series of visual search experiments conducted by Abrams et al. (2008) indicates that disengagement of visual attention is slowed when the array of objects that are to be searched are close to the hands (hands on the monitor) than if they are not close to the hands (hands in the lap). These experiments establish the impact one's hands can have on visual attentional processing. In the current paper we more closely examine these two hand postures with the goal of pinpointing which characteristics are crucial for the observed differences in attentional processing. Specifically, in a set of 4 experiments we investigated additional hand postures and additional modes of response to address this goal. We replicated the original Abrams et al. (2008) effect when only the two original postures were used; however, surprisingly, the effect was extinguished with the new range of postures and response modes, and this extinction persisted across different populations (German and English students), and different experimental hardware. Furthermore, analyses indicated that it is unlikely that the extinction of the effect was caused by increased practice due to additional blocks of trials or by an increased probability that participants were able to guess the purpose of the experiment. As such our results suggest that in addition to the nature of the postures of the hand, the number of postures is a further important factor that influences the impact the hands have on visual processing.

When what you hear influences when you see: listening to an auditory rhythm influences the temporal allocation of visual attention.

The three experiments reported here demonstrated a cross-modal influence of an auditory rhythm on the temporal allocation of visual attention. In Experiment 1, participants moved their eyes to a test dot with a temporal onset that was either synchronous or asynchronous with a preceding auditory rhythm. Saccadic latencies were faster for the synchronous condition than for the asynchronous conditions. In Experiment 2, the effect was replicated in a condition in which the auditory context stopped prior to the onset of the test dot, and the effect did not occur in a condition in which auditory tones were presented at irregular intervals. Experiment 3 replicated the effect using an accuracy measure within a nontimed visual task. Together, the experiments' findings support a general entrainment perspective on attention to events over time.

Selecting a reference object.

One way to describe the location of an object is to relate it to another object. Often there are many nearby objects, each of which could serve as a candidate to be the reference object. A common theoretical assumption is that features that make a given object salient relative to the candidate set are instrumental in determining which is selected. The current research tests this assumption, assessing the relative importance of spatial, perceptual, and functional-interactive features. Three experiments demonstrated that spatial features have the strongest influence on reference object selection, with the perceptual feature of color playing no significant role. Functional-interactive features were shown to be spatially dependent, having an influence only when the spatial configuration enabled an interaction between the located object and the reference object. These findings challenge the common perspective that salience in and of itself dictates reference object selection and argue for a reliance on spatial features.

Introduction to the special section on spatial reference frames: examining what and how information is encoded through the integration of cognitive, behavioral, and neuroscience approaches.

A spatial reference frame is a system of axes that assigns coordinate values to objects and regions in a given space and can serve as a means for specifying spatial information such as orientation and position. A longstanding literature has focused on the encoding of spatial position, examining what and how that information is encoded. The set of articles selected for this special section present current research on these two themes and are distinguished by their integration of cognitive, behavioral, and neuroscience approaches.

Processing the presence, placement, and properties of a distractor in spatial language tasks.

A common way to describe the location of an object is to spatially relate it to a nearby object. For such descriptions, the object being described is referred to as the located object; the object to which it is spatially related is referred to as the reference object. Typically, however, there are many nearby objects (distractors), resulting in the need for selection. We report three experiments that examine the extent to which a distractor in the display is processed during the selection of a reference object. Using acceptability ratings and production measures, we show that the presence and the placement ofa distractor have a significant impact on the assessment of the spatial relation between the located and reference objects; there is also evidence that the properties of the distractor are processed, but only under limited conditions. One implication is that the dimension that is most relevant to reference object selection is its spatial relation to the located object, rather than its salience with respect to other objects in the display.

Inhibition within a reference frame during the interpretation of spatial language.

Spatial terms such as right are potentially ambiguous because they can refer to different regions of space when defined by competing reference frames (e.g., my right within a relative reference frame versus an object's right within an intrinsic reference frame). In such situations, previous research has suggested that multiple reference frames are initially activated, followed by inhibition of the reference frame that is not ultimately selected to define the spatial term. Reference frames are complex multi-component representations, raising the question of exactly which components of the non-selected frame are inhibited. It is possible that the whole frame may be inhibited, including all axes and endpoints, or that only select endpoints and axes may be inhibited. Three experiments conducted using a negative priming paradigm revealed that only certain components of the non-selected reference frame were inhibited, consistent with the idea that some axes are privileged. These results also suggest that the components of a reference frame can be independently accessed. Implications for representing and accessing spatial information are discussed.

Interpreting spatial terms involves simulating interactions.

Recent research in spatial language has demonstrated that the interpretation of a spatial term depends not only on the geometry of the configuration of the objects being spatially related, but also on extrageometric information, including information about the objects and their interaction. Such effects could emerge from activation of general knowledge of the association between the objects; thus, they should be widely observed. In contrast, they could be more restricted, emerging only in situations in which the spatial language task positions objects in a manner that is consistent with a simulation of their interaction. In two experiments, we test each of these ideas and demonstrate that extrageometric information augments geometric information in the interpretation of spatial terms only when the situation enables the interaction.

Inhibition of attended processing during saccadic eye movements.

People are unable to perform some, but not all, cognitive tasks while moving their eyes. A possible common denominator among disrupted processes is the use of attention. The present research proposes and tests an attentional suppression hypothesis to evaluate this claim. This hypothesis states that because attention is obligatorily allocated to a to-be-fixated location prior to the onset of a saccade, during saccadic events attentional resources are unavailable to direct processing associated with higher order cognitive tasks. Subjects were engaged in a task that combined saccades and shifts of attention across global and local levels of hierarchical figures. When the eyes did not move, this shift took place between stimulus presentations. When saccades intervened between the stimuli, the global-local shifts of attention were interrupted, suggesting that saccades suppress cognitive processes requiring attention.

Neural correlates of spatial term use.

The current research used event-related brain potentials (ERPs) to assess the processes underlying online apprehension of the spatial term above. Constituent steps defined within G. D. Logan and D. D. Sadler's (1996) computational theory of apprehension were associated with distinct modulations of ERPs. Specifically, finding the relevant objects was associated with an amplitude modulation of P3; competition in assigning directions to space was associated with modulation of a frontal slow wave; and computing and comparing the spatial relation was associated with modulation of a parietal slow wave. These modulations were differentially influenced by the type of reference frame used to define the spatial term and by the participant's response. The current study supports this decompositional approach to apprehension and provides a means of assessing each step independently.