Chinook salmon depth distributions on the continental shelf are shaped by interactions between location, season, and individual condition.

BACKGROUND: Ecological and physical conditions vary with depth in aquatic ecosystems, resulting in gradients of habitat suitability. Although variation in vertical distributions among individuals provides evidence of habitat selection, it has been challenging to disentangle how processes at multiple spatio-temporal scales shape behaviour. METHODS: We collected thousands of observations of depth from > 300 acoustically tagged adult Chinook salmon Oncorhynchus tshawytscha, spanning multiple seasons and years. We used these data to parameterize a machine-learning model to disentangle the influence of spatial, temporal, and dynamic oceanographic variables while accounting for differences in individual condition and maturation stage. RESULTS: The top performing machine learning model used bathymetric depth ratio (i.e., individual depth relative to seafloor depth) as a response. We found that bathymetry, season, maturation stage, and spatial location most strongly influenced Chinook salmon depth. Chinook salmon bathymetric depth ratios were deepest in shallow water, during winter, and for immature individuals. We also identified non-linear interactions among covariates, resulting in spatially-varying effects of zooplankton concentration, lunar cycle, temperature and oxygen concentration. CONCLUSIONS: Our results suggest Chinook salmon vertical habitat use is a function of ecological interactions, not physiological constraints. Temporal and spatial variation in depth distributions could be used to guide management decisions intended to reduce fishery impacts on Chinook salmon. More generally, our findings demonstrate how complex interactions among bathymetry, seasonality, location, and life history stage regulate vertical habitat selection.

A rare case of perforated gastric duplication cyst associated with gastric diverticulum.

A 50-year-old man presented to the emergency department with a 1-day history of severe epigastric pain, vomiting and fever. He had a background of alcohol excess and smoking. The patient was tachycardic and febrile with an elevated white blood cell count and C reactive protein. CT demonstrated extensive upper abdominal free fluid, without free air, with a large cystic lesion arising from the greater curvature of the stomach, and a second smaller cystic lesion arising from the posterior aspect of the gastric fundus. The patient was managed with nasogastric drainage, parenteral nutrition, intravenous antibiotics and proton pump inhibitors, and CT-guided abdominal drainage, with resolution of sepsis, and further outpatient care was transferred to our unit. Follow-up endoscopy demonstrated a diverticulum arising from the posterior aspect of the gastric fundus, with normal mucosa throughout the remaining stomach, while CT showed an additional cystic lesion arising from the greater curvature, with thickening of the adjacent gastric wall consistent with a gastric duplication cyst (GDC). Laparoscopy confirmed a small diverticulum at the fundus, and a large GDC anteriorly with associated omental adhesions consistent with prior perforation-two wedge resections were performed. Histology demonstrated no evidence of malignancy or ectopic mucosa. The patient recovered uneventfully and remained free from recurrent symptoms at 6 weeks postoperatively. GDC is a rare entity, which may be associated with ectopic mucosa, malignant transformation and upper gastrointestinal perforation. No previous report describes the coexistence of a GDC and gastric diverticulum. Herein we describe the investigation and management of this condition, and review the associated peer-reviewed literature.

Effects of Virtual Exercise Rehabilitation In-Home Therapy Compared with Traditional Care After Total Knee Arthroplasty: VERITAS, a Randomized Controlled Trial.

BACKGROUND: Financial burden for patients, providers, and payers can reduce access to physical therapy (PT) after total knee arthroplasty (TKA). The purpose of the present study was to examine the effect of a virtual PT program on health-care costs and clinical outcomes as compared with traditional care after TKA. METHODS: At least 10 days before unilateral TKA, patients from 4 clinical sites were enrolled and randomized 1:1 to the virtual PT program (involving an avatar [digitally simulated] coach, in-home 3-dimensional biometrics, and telerehabilitation with remote clinician oversight by a physical therapist) or to traditional PT care in the home or outpatient clinic. The primary outcome was total health-care costs for the 12-week post-hospital period. Secondary (noninferiority) outcomes included 6 and 12-week Knee injury and Osteoarthritis Outcome Score (KOOS); 6-week knee extension, knee flexion, and gait speed; and 12-week safety measures (patient-reported falls, pain, and hospital readmissions). All outcomes were analyzed on a modified intent-to-treat basis. RESULTS: Of 306 patients (mean age, 65 years; 62.5% women) who were randomized from November 2016 to November 2017, 290 had TKA and 287 (including 143 in the virtual PT group and 144 in the usual care group) completed the trial. Virtual PT had lower costs at 12 weeks after discharge than usual care (median, $1,050 compared with $2,805; p < 0.001). Mean costs were $2,745 lower for virtual PT patients. Virtual PT patients had fewer rehospitalizations than the usual care group (12 compared with 30; p = 0.007). Virtual PT was noninferior to usual PT in terms of the KOOS at 6 weeks (difference, 0.77; 90% confidence interval [CI], -1.68 to 3.23) and 12 weeks (difference, -2.33; 90% CI, -4.98 to 0.31). Virtual PT was also noninferior to usual care at 6 weeks in terms of knee extension, knee flexion, and gait speed and at 12 weeks in terms of pain and hospital readmissions. Falls were reported by 19.4% of virtual PT patients and 14.6% of usual care patients (difference, 4.83%; 90% CI, -2.60 to 12.25). CONCLUSIONS: Relative to traditional home or clinic PT, virtual PT with telerehabilitation for skilled clinical oversight significantly lowered 3-month health-care costs after TKA while providing similar effectiveness. These findings have important implications for patients, health systems, and payers. Virtual PT with clinical oversight should be considered for patients managed with TKA. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Sex biased individual variation in movement patterns of a highly mobile, near-shore marine planktivore, the reef manta ray Mobula alfredi.

We examined individual variation and the role of sex on the movements of the reef manta ray Mobula alfredi. Specifically, we analysed several movement metrics using 6 years of nightly observations (1 January 2009-31 December 2014) of 118 individually identifiable manta rays at two discrete but spatially proximate sites, locally known as Manta Heaven and Manta Village, 15 km apart on the west side of the island of Hawaii, USA. Males were slightly more often (33.5%, model fitted mean, P < 0.05) observed than females at Manta Heaven, but females were much more often (156.4%, model fitted mean, P < 0.05) observed at Manta Village. Movement patterns among individuals varied greatly, but the level of variation was similar between sexes. Some animals, mainly females, displayed more resident patterns, whereas other, more mobile, animals moved between sites more frequently and had longer gaps between sightings. We did not detect discrete behavioural groups; rather, individuals varied along a continuous spectrum from many observations and high affinity to few observations and low fidelity to survey locations. These complex and variable movement patterns observed at the individual level, between sexes and between two nearby sites, in Hawaii's manta rays highlight the need for finer scale considerations in conservation and management of highly mobile marine populations.

Identifying keystone habitats with a mosaic approach can improve biodiversity conservation in disturbed ecosystems.

Conserving native biodiversity in the face of human- and climate-related impacts is a challenging and globally important ecological problem that requires an understanding of spatially connected, organismal-habitat relationships. Globally, a suite of disturbances (e.g., agriculture, urbanization, climate change) degrades habitats and threatens biodiversity. A mosaic approach (in which connected, interacting collections of juxtaposed habitat patches are examined) provides a scientific foundation for addressing many disturbance-related, ecologically based conservation problems. For example, if specific habitat types disproportionately increase biodiversity, these keystones should be incorporated into research and management plans. Our sampling of fish biodiversity and aquatic habitat along ten 3-km sites within the Upper Neosho River subdrainage, KS, from June-August 2013 yielded three generalizable ecological insights. First, specific types of mesohabitat patches (i.e., pool, riffle, run, and glide) were physically distinct and created unique mosaics of mesohabitats that varied across sites. Second, species richness was higher in riffle mesohabitats when mesohabitat size reflected field availability. Furthermore, habitat mosaics that included more riffles had greater habitat diversity and more fish species. Thus, riffles (<5% of sampled area) acted as keystone habitats. Third, additional conceptual development, which we initiate here, can broaden the identification of keystone habitats across ecosystems and further operationalize this concept for research and conservation. Thus, adopting a mosaic approach can increase scientific understanding of organismal-habitat relationships, maintain natural biodiversity, advance spatial ecology, and facilitate effective conservation of native biodiversity in human-altered ecosystems.

Habitat mosaics and path analysis can improve biological conservation of aquatic biodiversity in ecosystems with low-head dams.

Conserving native biodiversity depends on restoring functional habitats in the face of human-induced disturbances. Low-head dams are a ubiquitous human impact that degrades aquatic ecosystems worldwide. To improve our understanding of how low-head dams impact habitat and associated biodiversity, our research examined complex interactions among three spheres of the total environment. i.e., how low-head dams (anthroposphere) affect aquatic habitat (hydrosphere), and native biodiversity (biosphere) in streams and rivers. Creation of lake-like habitats upstream of low-head dams is a well-documented major impact of dams. Alterations downstream of low head dams also have important consequences, but these downstream dam effects are more challenging to detect. In a multidisciplinary field study at five dammed and five undammed sites within the Neosho River basin, KS, we tested hypotheses about two types of habitat sampling (transect and mosaic) and two types of statistical analyses (analysis of covariance and path analysis). We used fish as our example of biodiversity alteration. Our research provided three insights that can aid environmental professionals who seek to conserve and restore fish biodiversity in aquatic ecosystems threatened by human modifications. First, a mosaic approach identified habitat alterations below low-head dams (e.g. increased proportion of riffles) that were not detected using the more commonly-used transect sampling approach. Second, the habitat mosaic approach illustrated how low-head dams reduced natural variation in stream habitat. Third, path analysis, a statistical approach that tests indirect effects, showed how dams, habitat, and fish biodiversity interact. Specifically, path analysis revealed that low-head dams increased the proportion of riffle habitat below dams, and, as a result, indirectly increased fish species richness. Furthermore, the pool habitat that was created above low-head dams dramatically decreased fish species richness. As we show here, mosaic habitat sampling and path analysis can help conservation practitioners improve science-based management plans for disturbed aquatic systems worldwide.

eHealth: extending, enhancing, and evolving health care.

eHealth holds the promise of revolutionizing health care by improving its efficiency; extending and enhancing its reach; energizing and engaging its practitioners and their patients; and in the process, democratizing, decentralizing, and even partially demystifying the practice of medicine. In emerging and developing countries, the use of eHealth and smart health-care planning has the potential to expand access to necessary treatments and prevention services that can serve as underpinnings of rapid economic development. In developed countries, the application of eHealth promises to restructure the business model of health-care delivery, while at the same time improving and personalizing the quality of care received. This article reviews the past, present, and future of eHealth in an effort to illuminate the potential of its impact.

Preventing tomorrow's sudden cardiac death today: part II: Translating sudden cardiac death risk assessment strategies into practice and policy.

Although current evidence supporting a more precise strategy for identifying patients at highest risk for sudden cardiac death (SCD) is sparse, strategies for translating existing and future evidence into clinical practice and policy are needed today. A great many unanswered questions exist. Examples include the following: At what level of risk for SCD should we pursue further testing or therapy? How should clinical strategies ethically and economically balance alternative outcomes? How can we best translate optimal strategies into clinical practice so as to prevent tomorrow's SCDs? On July 20 and 21, 2006, a group of individuals with expertise in clinical cardiovascular medicine, biostatistics, economics, and health policy was joined by government (Food and Drug Administration; Centers for Medicare and Medicaid Services; National Heart, Lung, and Blood Institute; Agency for Healthcare Research and Quality), professional societies (Heart Rhythm Society), and industry to discuss strategies for risk assessment and prevention of SCD. The meeting was organized by the Duke Center for the Prevention of Sudden Cardiac Death and the Duke Clinical Research Institute. This article, the second of 2 documents, summarizes the policy discussions of that meeting, discusses an analytic framework for evaluating the risks and benefits associated with SCD prevention and risk stratification, and addresses the translation of SCD risk assessment strategies into practice and policy.

Pacing Evaluation-Atrial SUpport Study in Cardiac Resynchronization Therapy (PEGASUS CRT): design and rationale.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been demonstrated to be an effective heart failure (HF) therapy. All pivotal trials of CRT to date have used atrial-synchronous biventricular pacing wherein there is no or minimal atrial pacing. In clinical practice, however, physicians often program CRT devices to have atrial rate support pacing, either by increasing the lower rate limit or by activating the rate sensor. OBJECTIVE: The purpose of this study is to evaluate the effect of empiric atrial support pacing in patients with HF who have received a CRT defibrillator (CRT-D) device. METHODS: PEGASUS CRT is a multicenter, 3-arm, randomized clinical trial of approximately 1200 patients receiving a CRT-D device. For the first 6 weeks after implant, devices are programmed to DDD with a lower rate limit of 40 beats/min. At 6 weeks, patients are randomized to DDD-40, DDD-70, or DDDR-40. All randomized patients are followed for 1 year, and at each visit, mortality, HF events, quality of life, New York Heart Association class, and atrial and ventricular arrhythmic episodes are evaluated. An exercise substudy will also be conducted, enrolling a minimum of 375 patients. Patients in this substudy will complete 2 cardiopulmonary exercise tests to evaluate the effect pacing mode has on exercise capacity. This randomized controlled trial will address whether empiric atrial support pacing is of clinical benefit to patients with HF who receive a CRT-D device.

The Rhythm ID Going Head to Head Trial (RIGHT): design of a randomized trial comparing competitive rhythm discrimination algorithms in implantable cardioverter defibrillators.

BACKGROUND: The implantable cardioverter defibrillator (ICD) has become primary therapy for the prevention of sudden death. One of the major morbidities of ICD use remains inappropriate therapy for supraventricular arrhythmias (SVA). Detection enhancements have increased therapy specificity, but their impact on inappropriate therapy is not well studied. Moreover, ICD manufacturers have developed unique algorithms to meet this goal, with no previous clinical direct comparisons. RIGHT is a randomized, prospective study that will assess the differential efficacy of ICDs from two different manufacturers. It is the first trial to compare directly competitive ICD rhythm discrimination algorithms on a large scale. OBJECTIVE: The primary objective of this study is to assess arrhythmia discrimination in Guidant versus Medtronic ICDs by comparing the time to first inappropriate therapy after the predischarge visit. METHODS: The study will enroll approximately 2,000 patients in 100 centers. Patients will be randomized to Guidant or Medtronic using a permuted block design, stratified by center and by single/dual chamber device types. Patients will receive a commercially available Guidant VITALITY 2 family ICD with Rhythm ID or a Medtronic ICD using the Enhanced PR Logic or Wavelet discrimination algorithms, and will be followed according to the schedule shown until a common closing date with a minimum follow-up of 12 months. All events will be reviewed by an independent committee to determine the appropriateness of rhythm classification and therapy delivery. CONCLUSION: RIGHT is the first randomized, large scale, head-to-head comparison of ICD discrimination algorithms.

Relation of T-wave alternans to regional left ventricular dysfunction and eccentric hypertrophy secondary to coronary heart disease.

Left ventricular (LV) hypertrophy and structural disease are associated with exaggerated repolarization dispersion and risk for cardiac arrest. We hypothesized that T-wave alternans (TWA) from the electrocardiogram, reflecting proarrhythmic repolarization dispersion, would increase with extent of eccentric LV hypertrophy and vary spatially with the distribution of myocardial scar. We studied 28 patients with coronary disease, systolic dysfunction, and nonsustained ventricular tachycardia. On echocardiography, 21 patients had wall motion abnormalities and 20 had LV hypertrophy (mass index > or =100 g/m(2)). TWA magnitude (voltage of alternation), which was computed spectrally during ventricular stimulation, varied linearly with LV mass index (p = 0.003). Spatially, positive TWA (magnitude > or =1.9 microV) in orthogonal electrocardiographic axes overlaid scar or wall motion abnormalities in corresponding echocardiographic segments (p <0.05 in x and y axes). After a follow-up of 35 +/- 13 months, positive TWA predicted the combined end point of death or sustained ventricular arrhythmias in all patients (p = 0.025), with a trend for those with echocardiographic LV hypertrophy (p = 0.058). In conclusion, in patients with systolic dysfunction due to coronary artery disease, TWA may indicate arrhythmic contributions from regional myocardial scar and eccentric LV hypertrophy.

T-wave alternans phase following ventricular extrasystoles predicts arrhythmia-free survival.

OBJECTIVE: The purpose of this study was to assess the value of T-wave alternans (TWA) following ventricular extrasystoles in predicting arrhythmia-free survival. BACKGROUND: Stratifying risk for sudden death in patients with coronary disease and moderate left ventricular (LV) dysfunction remains a challenge. We hypothesized that, in such patients, a discontinuity in beat-to-beat T-wave alternation (TWA phase reversal) following single ventricular extrasystoles reflects transiently exaggerated repolarization dispersion, and predicts spontaneous ventricular arrhythmias. METHODS: We studied 59 patients with ischemic LV dysfunction (mean LV ejection fraction 38.7 +/- 5.3%) and nonsustained ventricular tachycardia undergoing programmed stimulation. TWA was computed spectrally from the ECG during ventricular pacing, and TWA phase reversal was reflected by a discontinuity in T-wave oscillation after single ventricular extrasystoles. RESULTS: Patients induced into ventricular arrhythmias (n = 36) had greater TWA magnitude (V(alt): 6.60 +/- 6.46 microV vs 2.61 +/- 1.97 microV; P = .001) and more frequent TWA phase reversal (62.1% vs 44.4%; P = .02) than those who were not (n = 23). During a mean follow-up of 36 +/- 12 months, positive TWA (V(alt) > or =1.9 microV) and TWA phase reversal both (P < .05) predicted events (all-cause mortality, ventricular tachycardia, ventricular fibrillation). Univariate predictors of arrhythmia-free survival were TWA phase reversal (P < .005), positive TWA (P < .05), age (P = .008), and LV mass index (P = .043). On multivariate analysis, only TWA phase reversal and age predicted events; if TWA phase was excluded, only positive TWA and age predicted events. CONCLUSION: Phase reversal in TWA following ventricular extrasystoles predicts spontaneous ventricular arrhythmias and all-cause mortality in patients with moderate ischemic LV dysfunction and was a better predictor than positive TWA or programmed ventricular stimulation.

ICD Therapy for the Prevention of Sudden Cardiac Death in Post-MI Patients.

Implantable cardioverter-defibrillators (ICDs) are unequivocally the treatment of choice for patients who have already experienced a near-fatal tachyarrhythmic event. Recently, studies have conclusively demonstrated that extending the benefits of ICD therapy to postinfarction patients with resultant left ventricular dysfunction results in dramatic additional lifesaving without the need for complex risk- stratification procedures. The landmark Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) shows that patients with reduced left ventricular function (ejection fraction < 30%) 1 month after a myocardial infarction should receive an ICD to prevent sudden cardiac death.