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1.  Species–energy relationships in deep-sea molluscs 
Biology Letters  2011;7(5):718-722.
Consensus is growing among ecologists that energy and the factors influencing its utilization can play overarching roles in regulating large-scale patterns of biodiversity. The deep sea—the world's largest ecosystem—has simplified energetic inputs and thus provides an excellent opportunity to study how these processes structure spatial diversity patterns. Two factors influencing energy availability and use are chemical (productive) and thermal energy, here represented as seafloor particulate organic carbon (POC) flux and temperature. We related regional patterns of benthic molluscan diversity in the North Atlantic to these factors, to conduct an explicit test of species–energy relationships in the modern day fauna of the deep ocean. Spatial regression analyses in a model-averaging framework indicated that POC flux had a substantially higher relative importance than temperature for both gastropods and protobranch bivalves, although high correlations between variables prevented definitive interpretation. This contrasts with recent research on temporal variation in fossil diversity from deep-sea cores, where temperature is generally a more significant predictor. These differences may reflect the scales of time and space at which productivity and temperature operate, or differences in body size; but both lines of evidence implicate processes influencing energy utilization as major determinants of deep-sea species diversity.
PMCID: PMC3169037  PMID: 21429909
species–energy; productivity; temperature; mollusc; diversity
2.  Transcatheter versus Surgical Aortic Valve Replacement in Patients with Diabetes and Severe Aortic Stenosis at High Risk for Surgery: An Analysis of the PARTNER Trial 
To determine whether a less invasive approach to aortic valve replacement (AVR) improves clinical outcomes in diabetic patients with aortic stenosis (AS).
Diabetes is associated with increased morbidity and mortality after surgical AVR for AS.
Among treated patients with severe symptomatic AS at high-risk for surgery in the PARTNER trial, we examined outcomes stratified by diabetes status of patients randomly assigned to transcatheter or surgical AVR. The primary outcome was all-cause mortality at 1 year.
Among 657 patients enrolled in PARTNER who underwent treatment, there were 275 patients with diabetes (145 transcatheter, 130 surgical). There was a significant interaction between diabetes and treatment group for 1-year all-cause mortality (p=0.048). Among diabetic patients, all-cause mortality at 1 year was 18.0% in the transcatheter group and 27.4% in the surgical group (HR 0.60; 95% CI, 0.36–0.99; p=0.04). Results were consistent among patients treated via transfemoral or transapical routes. In contrast, among non-diabetic patients, there was no significant difference in all-cause mortality at 1 year (p=0.48). Among diabetic patients, the 1-year rates of stroke were similar between treatment groups (3.5% transcatheter vs. 3.5% surgery, p=0.88), but the rates of renal failure requiring dialysis >30 days were lower in the transcatheter group (0% vs. 6.1%, p=0.003).
Among patients with diabetes and severe symptomatic AS at high-risk for surgery, this post-hoc stratified analysis of the PARTNER trial suggests there is a survival benefit, no increase in stroke, and less renal failure from treatment with transcatheter compared to surgical AVR.
PMCID: PMC3962709  PMID: 24291272
aortic stenosis; transcatheter aortic valve replacement; diabetes
3.  Myocardial Protection Using del Nido Cardioplegia Solution in Adult Reoperative Aortic Valve Surgery 
Journal of cardiac surgery  2014;29(4):445-449.
Background and Aims
The immediate post-ischemic period is marked by elevated intracellular calcium levels which can lead to irreversible myocyte injury. Del Nido cardioplegia was developed for use in the pediatric population to address the inability of immature myocardium to tolerate high levels of intracellular calcium following cardiac surgery. Our aim in this study is to determine if this solution can be used safely and effectively in an adult, re-operative population.
All patients undergoing isolated re-operative aortic valve replacement at our institution from 2010 to 2012 were retrospectively reviewed. Demographics, co-morbidities, operative variables, post-operative complications, and patient outcomes were collected. Patients were divided into 2 groups based on cardioplegia strategy used: Whole blood cardioplegia (WB, n=61) and del Nido cardioplegia (DN, n=52).
Mean age in the study was 73.4 ± 14.3 years and 86 patients were male (76.1%). Eighty-four patients had undergone prior CABG (74.3%). Patients in the DN group required significantly lower total volume of cardioplegia (1147.6 ± 447.2 mL DN vs. 1985.4 ± 691.1 mL WB, p<0.001) and retrograde cardioplegia dose (279.3 ± 445.1 mL DN vs. 1341.2 ± 690.8 mL WB, p<0.001). There were no differences in cross-clamp time, bypass time, post-operative complication rate, or patient outcomes between groups.
Del Nido cardioplegia use in an adult, re-operative aortic valve population offers equivalent post-operative outcomes when compared with whole blood cardioplegia. In addition, use of del Nido solution requires lower total and retrograde cardioplegia volumes in order to achieve adequate myocardial protection.
PMCID: PMC4297647  PMID: 24861160
Valve repair/replacement; perfusion
4.  Del Nido Cardioplegia can be safely administered in high-risk coronary artery bypass grafting surgery after acute myocardial infarction: a propensity matched comparison 
Del Nido (DN) cardioplegia solution provides a depolarized hyperkalemic arrest lasting up to 60 minutes, and the addition of lidocaine may limit intracellular calcium influx. Single-dose DN cardioplegia solution may offer an alternative myocardial protection strategy to multi-dose cold whole blood (WB) cardioplegia following acute myocardial infarction (AMI).
We retrospectively reviewed 88 consecutive patients with AMI undergoing coronary artery bypass (CABG) surgery with cardioplegic arrest between June 2010 to June 2012. Patients exclusively received WB (n = 40, June 2010-July 2011) or DN (n = 48, August 2011-June 2012) cardioplegia. Preoperative and postoperative data were retrospectively reviewed and compared using propensity scoring.
No significant difference in age, maximum preoperative serum troponin level, ejection fraction, and STS score was present between DN and WB. A single cardioplegia dose was given in 41 DN vs. 0 WB patients (p < 0.001), and retrograde cardioplegia was used 10 DN vs. 31 WB patients (p < 0.001). Mean cardiopulmonary bypass and cross clamp times were significantly shorter in the DN group versus WB group. Tranfusion rate, length of stay, intra-aortic balloon pump requirement, post-operative inotropic support, and 30-day mortality was no different between groups. One patient in the WB group required a mechanical support due to profound cardiogenic shock.
DN cardioplegia may provide equivalent myocardial protection to existing cardioplegia without negative inotropic effects in the setting of acute myocardial infarction.
PMCID: PMC4220058  PMID: 25359427
Coronary artery bypass grafting; Myocardial protection; Acute myocardial infarction
5.  Primary Endpoints of the Biventricular Pacing after Cardiac Surgery Trial 
The Annals of thoracic surgery  2013;96(3):10.1016/j.athoracsur.2013.04.101.
To determine whether optimized biventricular pacing increases cardiac index in patients at risk of left ventricular dysfunction after cardiopulmonary bypass. Procedures included coronary artery bypass, aortic or mitral surgery and combinations. This trial was approved by the Columbia University Institutional Review Board and was conducted under an Investigational Device Exemption.
Screening of 6,346 patients yielded 47 endpoints. With informed consent, 61 patients were randomized to pacing or control groups. Atrioventricular and interventricular delays were optimized one (Phase I), two (Phase II), and 12–24 hours (Phase III) after bypass in all patients. Cardiac index was measured by thermal dilution in triplicate. Two-sample t-test assessed differences between groups and subgroups.
Cardiac index was 12% higher (2.83±0.16 (S.E.M.) vs. 2.52±0.13 liters/minute/square meter) in the paced group, less than predicted and not statistically significant (p=0.14). However, when aortic and aortic/mitral surgery groups were combined, cardiac index increased 29% in the paced group (2.90±0.19, n=14) vs. controls (2.24±0.15, n=11) (p=0.0138). Using a linear mixed effects model, t-test revealed that mean arterial pressure increased with pacing vs. no pacing at all optimization points (Phase I 79.2±1.7 vs. 74.5±1.6 mmHg, p=0.008, Phase II 75.9±1.5 vs. 73.6±1.8, p=0.006, Phase III 81.9±2.8 vs. 79.5±2.7, p=0.002)
Cardiac index did not increase significantly overall but increased 29% after aortic valve surgery. Mean arterial pressure increased with pacing at three time points. Additional studies are needed to distinguish rate from resynchronization effects, emphasize atrioventricular delay optimization, and examine clinical benefits of temporary postoperative pacing.
PMCID: PMC3882062  PMID: 23866800
Pacemaker; CPB; Myocardium; Heart failure; Physiology/heart
6.  Long-Term Mortality of Coronary Artery Bypass Graft Surgery and Stenting with Drug-Eluting Stents 
The Annals of thoracic surgery  2013;95(4):1297-1305.
Few studies have examined differences in long-term mortality between coronary artery bypass graft surgery and stenting with drug-eluting stents (DES) for multivessel disease without left main coronary artery stenosis. This study compares the risks of long-term mortality between these 2 procedures during a follow-up of up to 5 years.
Patients who underwent isolated bypass surgery (n=13,212) and stenting with DES (n=20,161) between October 2003 and December 2005 in New York State were followed for their vital status through 2008. To control for treatment selection bias, bypass and stenting patients were matched on age, number of diseased coronary vessels, presence of proximal or nonproximal left anterior descending (LAD) artery disease, and propensity of undergoing bypass surgery. Five-year survival rates for the 2 procedures were compared and hazard ratios for death of bypass surgery compared to stenting were obtained.
The respective 5-year survival rates in the 8,121 pairs of matched bypass and stenting patients were 80.4%and 73.6% (P<0.001), and the risk of death following bypass surgery was 29% lower than for stenting (hazard ratio=0.71, 95% confidence interval: 0.67-0.77, P<0.001). Significantly lower risks of death for bypass surgery were observed in patients with LAD artery disease but not in patients without LAD artery disease. Significantly lower risks of death for bypass surgery were also found in all patient subgroups defined by the presence of selected baseline risk factors.
Bypass surgery is associated with lower risk of death than stenting with DES for multivessel disease without left main stenosis.
PMCID: PMC3756666  PMID: 23391171
CABG; stents; outcomes
7.  Megafaunal Communities in Rapidly Warming Fjords along the West Antarctic Peninsula: Hotspots of Abundance and Beta Diversity 
PLoS ONE  2013;8(12):e77917.
Glacio-marine fjords occur widely at high latitudes and have been extensively studied in the Arctic, where heavy meltwater inputs and sedimentation yield low benthic faunal abundance and biodiversity in inner-middle fjords. Fjord benthic ecosystems remain poorly studied in the subpolar Antarctic, including those in extensive fjords along the West Antarctic Peninsula (WAP). Here we test ecosystem predictions from Arctic fjords on three subpolar, glacio-marine fjords along the WAP. With seafloor photographic surveys we evaluate benthic megafaunal abundance, community structure, and species diversity, as well as the abundance of demersal nekton and macroalgal detritus, in soft-sediment basins of Andvord, Flandres and Barilari Bays at depths of 436–725 m. We then contrast these fjord sites with three open shelf stations of similar depths. Contrary to Arctic predictions, WAP fjord basins exhibited 3 to 38-fold greater benthic megafaunal abundance than the open shelf, and local species diversity and trophic complexity remained high from outer to inner fjord basins. Furthermore, WAP fjords contained distinct species composition, substantially contributing to beta and gamma diversity at 400–700 m depths along the WAP. The abundance of demersal nekton and macroalgal detritus was also substantially higher in WAP fjords compared to the open shelf. We conclude that WAP fjords are important hotspots of benthic abundance and biodiversity as a consequence of weak meltwater influences, low sedimentation disturbance, and high, varied food inputs. We postulate that WAP fjords differ markedly from their Arctic counterparts because they are in earlier stages of climate warming, and that rapid warming along the WAP will increase meltwater and sediment inputs, deleteriously impacting these biodiversity hotspots. Because WAP fjords also provide important habitat and foraging areas for Antarctic krill and baleen whales, there is an urgent need to develop better understanding of the structure, dynamics and climate-sensitivity of WAP subpolar fjord ecosystems.
PMCID: PMC3848936  PMID: 24312442
8.  Cold Seep Epifaunal Communities on the Hikurangi Margin, New Zealand: Composition, Succession, and Vulnerability to Human Activities 
PLoS ONE  2013;8(10):e76869.
Cold seep communities with distinctive chemoautotrophic fauna occur where hydrocarbon-rich fluids escape from the seabed. We describe community composition, population densities, spatial extent, and within-region variability of epifaunal communities at methane-rich cold seep sites on the Hikurangi Margin, New Zealand. Using data from towed camera transects, we match observations to information about the probable life-history characteristics of the principal fauna to develop a hypothetical succession sequence for the Hikurangi seep communities, from the onset of fluid flux to senescence. New Zealand seep communities exhibit taxa characteristic of seeps in other regions, including predominance of large siboglinid tubeworms, vesicomyid clams, and bathymodiolin mussels. Some aspects appear to be novel; however, particularly the association of dense populations of ampharetid polychaetes with high-sulphide, high-methane flux, soft-sediment microhabitats. The common occurrence of these ampharetids suggests they play a role in conditioning sulphide-rich sediments at the sediment-water interface, thus facilitating settlement of clam and tubeworm taxa which dominate space during later successional stages. The seep sites are subject to disturbance from bottom trawling at present and potentially from gas hydrate extraction in future. The likely life-history characteristics of the dominant megafauna suggest that while ampharetids, clams, and mussels exploit ephemeral resources through rapid growth and reproduction, lamellibrachid tubeworm populations may persist potentially for centuries. The potential consequences of gas hydrate extraction cannot be fully assessed until extraction methods and target localities are defined but any long-term modification of fluid flow to seep sites would have consequences for all chemoautotrophic fauna.
PMCID: PMC3800081  PMID: 24204691
9.  Biotic and Human Vulnerability to Projected Changes in Ocean Biogeochemistry over the 21st Century 
PLoS Biology  2013;11(10):e1001682.
Mora and colleagues show that ongoing greenhouse gas emissions are likely to have a considerable effect on several biogeochemical properties of the world's oceans, with potentially serious consequences for biodiversity and human welfare.
Ongoing greenhouse gas emissions can modify climate processes and induce shifts in ocean temperature, pH, oxygen concentration, and productivity, which in turn could alter biological and social systems. Here, we provide a synoptic global assessment of the simultaneous changes in future ocean biogeochemical variables over marine biota and their broader implications for people. We analyzed modern Earth System Models forced by greenhouse gas concentration pathways until 2100 and showed that the entire world's ocean surface will be simultaneously impacted by varying intensities of ocean warming, acidification, oxygen depletion, or shortfalls in productivity. In contrast, only a small fraction of the world's ocean surface, mostly in polar regions, will experience increased oxygenation and productivity, while almost nowhere will there be ocean cooling or pH elevation. We compiled the global distribution of 32 marine habitats and biodiversity hotspots and found that they would all experience simultaneous exposure to changes in multiple biogeochemical variables. This superposition highlights the high risk for synergistic ecosystem responses, the suite of physiological adaptations needed to cope with future climate change, and the potential for reorganization of global biodiversity patterns. If co-occurring biogeochemical changes influence the delivery of ocean goods and services, then they could also have a considerable effect on human welfare. Approximately 470 to 870 million of the poorest people in the world rely heavily on the ocean for food, jobs, and revenues and live in countries that will be most affected by simultaneous changes in ocean biogeochemistry. These results highlight the high risk of degradation of marine ecosystems and associated human hardship expected in a future following current trends in anthropogenic greenhouse gas emissions.
Author Summary
Climate change caused by human activity could damage biological and social systems. Here we gathered climate, biological, and socioeconomic data to describe some of the events by which ocean biogeochemical changes triggered by ongoing greenhouse gas emissions could cascade through marine habitats and organisms, eventually influencing humans. Our results suggest that the entire world's ocean surface will be simultaneously impacted by varying intensities of ocean warming, acidification, oxygen depletion, or shortfalls in productivity. Only a very small fraction of the oceans, mostly in polar regions, will face the opposing effects of increases in oxygen or productivity, and almost nowhere will there be cooling or pH increase. The biological responses to such biogeochemical changes could be considerable since marine habitats and hotspots for several marine taxa will be simultaneously exposed to biogeochemical changes known to be deleterious. The social ramifications are also likely to be massive and challenging as some 470 to 870 million people – who can least afford dramatic changes to their livelihoods – live in areas where ocean goods and services could be compromised by substantial changes in ocean biogeochemistry. These results underline the need for urgent mitigation of greenhouse gas emissions if degradation of marine ecosystems and associated human hardship are to be prevented.
PMCID: PMC3797030  PMID: 24143135
10.  Bone-eating worms from the Antarctic: the contrasting fate of whale and wood remains on the Southern Ocean seafloor 
We report the results from the first experimental study of the fate of whale and wood remains on the Antarctic seafloor. Using a baited free-vehicle lander design, we show that whale-falls in the Antarctic are heavily infested by at least two new species of bone-eating worm, Osedax antarcticus sp. nov. and Osedax deceptionensis sp. nov. In stark contrast, wood remains are remarkably well preserved with the absence of typical wood-eating fauna such as the xylophagainid bivalves. The combined whale-fall and wood-fall experiment provides support to the hypothesis that the Antarctic circumpolar current is a barrier to the larvae of deep-water species that are broadly distributed in other ocean basins. Since humans first started exploring the Antarctic, wood has been deposited on the seafloor in the form of shipwrecks and waste; our data suggest that this anthropogenic wood may be exceptionally well preserved. Alongside the new species descriptions, we conducted a comprehensive phylogenetic analyses of Osedax, suggesting the clade is most closely related to the frenulate tubeworms, not the vestimentiferans as previous reported.
PMCID: PMC3757972  PMID: 23945684
whale-fall; wood-fall; Annelida; Polychaeta; Siboglinidae; Xylophaga
11.  Repair of paravalvular prosthetic mitral valve leaks with septal occluder devices in severely high-risk patients: a word of caution 
Paravalvular leak following a mitral valve replacement is a complication seen in approximately 1 of 10 replacements. The corrective method has traditionally been reoperation. Septal occluder devices are more commonly being utilized as an alternative percutaneous correction method. We report the use of septal occluder devices in the repair of mitral paravalvular leak in two patients at severely high EuroSCORE II mortality risk. In both patients, the occluder devices became unstable, leading to a recurrence of severe paravalvular leak.
PMCID: PMC3422933  PMID: 22641840
Minimally invasive; Valve repair; Percutaneous; Mitral valve; Valvular leak
12.  The Impact of Frailty Status on Survival After Transcatheter Aortic Valve Replacement in Older Adults With Severe Aortic Stenosis 
This study sought to evaluate the impact of frailty in older adults undergoing transcatheter aortic valve replacement (TAVR) for symptomatic aortic stenosis.
Frailty status impacts prognosis in older adults with heart disease; however, the impact of frailty on prognosis after TAVR is unknown.
Gait speed, grip strength, serum albumin, and activities of daily living status were collected at baseline and used to derive a frailty score among patients who underwent TAVR procedures at a single large-volume institution. The cohort was dichotomized on the basis of median frailty score into frail and not frail groups. The impact of frailty on procedural outcomes (stroke, bleeding, vascular complications, acute kidney injury, and mortality at 30 days) and 1-year mortality was evaluated.
Frailty status was assessed in 159 subjects who underwent TAVR (age 86 ± 8 years, Society of Thoracic Surgery Risk Score 12 ± 4). Baseline frailty score was not associated with conventionally ascertained clinical variables or Society of Thoracic Surgery score. Although high frailty score was associated with a longer post-TAVR hospital stay when compared with lower frailty score (9 ± 6 days vs. 6 ± 5 days, respectively, p = 0.004), there were no significant crude associations between frailty status and procedural outcomes, suggesting adequacy of the standard selection process for identifying patients at risk for periprocedural complications after TAVR. Frailty status was independently associated with increased 1-year mortality (hazard ratio: 3.5, 95% confidence interval: 1.4 to 8.5, p = 0.007) after TAVR.
Frailty was not associated with increased periprocedural complications in patients selected as candidates to undergo TAVR but was associated with increased 1-year mortality after TAVR. Further studies will evaluate the independent value of this frailty composite in older adults with aortic stenosis.
PMCID: PMC3717525  PMID: 22995885
aortic stenosis; frailty; transcatheter valve
13.  Gait Speed and Dependence in Activities of Daily Living in Older Adults With Severe Aortic Stenosis 
Clinical cardiology  2012;35(5):307-314.
In the transcatheter aortic valve replacement era, characterization of functional status in older adults with aortic stenosis (AS) is essential. Gait speed (GS) is emerging as a marker of frailty and predictor of outcomes in older adults undergoing cardiovascular intervention. The objective of this study was to delineate the prevalence of slow GS, evaluate the association of GS with factors used in standard cardiovascular assessments, and evaluate the association of GS with dependence in activities of daily living (ADLs) in older adults with AS.
We hypothesized that gait speed would not be associated with clinical factors, but would be associated with ADLs.
We evaluated GS, ADLs dependence, and Society of Thoracic Surgery score along with clinical and functional assessments in 102 older adults with AS being evaluated for transcatheter valve. Gait speed <0.5 m/s was considered slow, and GS ≥0.5 m/s was considered preserved. We assessed the association of covariates with GS as well as with ADLs dependence.
Median GS was 0.37 m/s (interquartile range, 0.0–0.65 m/s). Sixty-four (63%) subjects had slow GS. Of commonly employed clinical covariates, only prior coronary intervention and serum albumin were weakly associated with GS. However, GS was independently associated with ADLs dependence (Odds ratio: 1.52 [1.21–1.91] for every 0.1 m/s decrease in GS; P = 0.0003).
Although the prevalence of slow GS in a population of elderly patients with severe AS being screened for transcatheter valve was high, there were only weak associations between GS and other risk stratifying tools. The strong association between GS and dependent functional status suggests that assessment of gait speed is a useful, objectively measurable, risk stratification tool in this population.
PMCID: PMC3702449  PMID: 22331630
14.  A Risk Score for Predicting Long-Term Mortality Following Coronary Artery Bypass Graft Surgery 
Circulation  2012;125(20):2423-2430.
No simplified bedside risk scores have been created to predict long-term mortality after coronary artery bypass graft (CABG) surgery.
Methods and Results
The New York State’s Cardiac Surgery Reporting System was used to identify 8,597 patients who underwent isolated CABG surgery in July-December 2000. The National Death Index was used to ascertain patients’ vital status through December 31, 2007. A Cox proportional hazards model was fit to predict death following CABG surgery using pre-procedural risk factors. Then points were assigned to significant predictors of death based on the values of their regression coefficients. For each possible point total, the predicted risks of death at years 1, 3, 5, and 7 were calculated. It was found that the 7-year mortality rate was 24.2% in the study population. Significant predictors of death included age, body mass index, ejection fraction, unstable hemodynamic state or shock, left main coronary artery disease, cerebrovascular disease, peripheral arterial disease, congestive heart failure, malignant ventricular arrhythmia, chronic obstructive pulmonary disease, diabetes, renal failure, and history of open heart surgery. The points assigned to these risk factors ranged from 1 to 7; and possible point totals for each patient ranged from 0 to 28. The observed and predicted risks of death at years 1, 3, 5, and 7 across patient groups stratified by point totals were highly correlated.
The simplified risk score accurately predicted the risk of mortality following CABG surgery, and can be used for informed consent and as an aid in determining treatment choice.
PMCID: PMC3422677  PMID: 22547673
CABG; follow-up studies; mortality; risk score
15.  A large population of king crabs in Palmer Deep on the west Antarctic Peninsula shelf and potential invasive impacts 
Lithodid crabs (and other skeleton-crushing predators) may have been excluded from cold Antarctic continental shelf waters for more than 14 Myr. The west Antarctic Peninsula shelf is warming rapidly and has been hypothesized to be soon invaded by lithodids. A remotely operated vehicle survey in Palmer Deep, a basin 120 km onto the Antarctic shelf, revealed a large, reproductive population of lithodids, providing the first evidence that king crabs have crossed the Antarctic shelf. DNA sequencing and morphology indicate the lithodid is Neolithodes yaldwyni Ahyong & Dawson, previously reported only from Ross Sea waters. We estimate a N. yaldwyni population density of 10 600 km−2 and a population size of 1.55 × 106 in Palmer Deep, a density similar to lithodid populations of commercial interest around Alaska and South Georgia. The lithodid occurred at depths of more than 850 m and temperatures of more than 1.4°C in Palmer Deep, and was not found in extensive surveys of the colder shelf at depths of 430–725 m. Where N. yaldwyni occurred, crab traces were abundant, megafaunal diversity reduced and echinoderms absent, suggesting that the crabs have major ecological impacts. Antarctic Peninsula shelf waters are warming at approximately 0.01°C yr−1; if N. yaldwyni is currently limited by cold temperatures, it could spread up onto the shelf (400–600 m depths) within 1–2 decades. The Palmer Deep N. yaldwyni population provides an important model for the potential invasive impacts of crushing predators on vulnerable Antarctic shelf ecosystems.
PMCID: PMC3259932  PMID: 21900324
lithodids; invasion; Antarctic; climate warming; bioturbation; biodiversity loss
16.  Folding mitral valvuloplasty without posterior leaflet resection for calcified mitral annulus 
Mitral valve annular calcification has long been a challenge in repairing posterior mitral valve prolapse. Folding valvuloplasty of the posterior leaflet without resection provides a means of circumventing common procedural complications. This report demonstrates the success of folding valvuloplasty without resection in the treatment of mitral valve prolapse and severe annular calcification.
PMCID: PMC3279970  PMID: 22159235
Mitral valve repair; Valvuloplasty; Calcification mitral annulus
17.  A Comparison of Long-Term Mortality for Off-Pump and On-Pump Coronary Artery Bypass Graft Surgery 
The survival difference between off-pump and on-pump coronary artery bypass graft (CABG) surgery for follow-up longer than 5 years is not well understood. The objective of this study is to examine the difference in 7-year mortality after these two procedures.
Methods and Results
New York State’s Cardiac Surgery Reporting System was used to identify the 2,640 off-pump and 5,940 on-pump isolated CABG patients discharged from July through December, 2000. The National Death Index was used to ascertain patients’ vital statuses through 2007. A logistic regression model was fit to predict the probability of receiving an off-pump procedure using baseline patient characteristics. Off-pump and on-pump patients were matched with a 1:1 ratio based on the probability of receiving an off-pump procedure. Kaplan-Meier survival curves for the 2 procedures were compared using the propensity-matched data, and the hazard ratio for death for off-pump in comparison to on-pump procedures was obtained. In subgroup analyses, the significance of interactions between type of surgery and baseline risk factors was tested. In this study, 2,631 pairs of off-pump and on-pump patients were propensity matched. The 7-year Kaplan-Meier survival rates were 71.2% and 73.4% (P=0.07) for off-pump and on-pump surgery, respectively. The hazard ratio for death (off-pump vs. on-pump) was 1.10 (95% confidence interval: 0.99-1.21, P=0.07). No statistical significance was detected for the interaction terms between type of surgery and a number of different baseline risk factors.
The difference in long-term morality between on-pump and off-pump CABG surgery is not statistically significant.
PMCID: PMC3277259  PMID: 22235063
CABG; coronary artery disease; follow-up studies; mortality; off-pump surgery
18.  Feasibility of Temporary Biventricular Pacing after Off-Pump Coronary Artery Bypass Grafting in Patients with Reduced Left Ventricular Function 
Texas Heart Institute Journal  2013;40(4):403-409.
In selected patients undergoing cardiac surgery, our research group previously showed that optimized temporary biventricular pacing can increase cardiac output one hour after weaning from cardiopulmonary bypass. Whether pacing is effective after beating-heart surgery is unknown. Accordingly, in this study we examined the feasibility of temporary biventricular pacing after off-pump coronary artery bypass grafting.
The effects of optimized pacing on cardiac output were measured with an electromagnetic aortic flow probe at the conclusion of surgery in 5 patients with a preoperative mean left ventricular ejection fraction of 0.26 (range, 0.15–0.35). Atrioventricular (7) and interventricular (9) delay settings were optimized in randomized order.
Cardiac output with optimized biventricular pacing was 4.2 ± 0.7 L/min; in sinus rhythm, it was 3.8 ± 0.5 L/min. Atrial pacing at a matched heart rate resulted in cardiac output intermediate to that of sinus rhythm and biventricular pacing (4 ± 0.6 L/min). Optimization of atrioventricular and interventricular delay, in comparison with nominal settings, trended toward increased flow.
This study shows that temporary biventricular pacing is feasible in patients with preoperative left ventricular dysfunction who are undergoing off-pump coronary artery bypass grafting. Further study of the possible clinical benefits of this intervention is warranted.
PMCID: PMC3783126  PMID: 24082369
Arrhythmias, cardiac/therapy; cardiac pacing, artificial/methods; cardiac output, low/therapy; heart failure/therapy; stroke volume; ventricular dysfunction, left/complications/prevention & control
19.  A Minimally Invasive Approach is More Cost-Effective than a Traditional Sternotomy Approach for Mitral Valve Surgery 
The aim of this study was to compare the cost and effectiveness of a minimally invasive (MI) versus traditional sternotomy (ST) approach for mitral valve surgery (MVS).
From 1/1/03–12/31/08, 847 patients underwent isolated MVS at our institution. Propensity matching on 22 clinical variables was carried out to generate a study cohort of 434 patients (217 matched pairs). Direct and indirect costs from the hospital perspective were retrospectively obtained from our finance department. Total hospital costs were further stratified into 13 standardized institutional billing categories. In addition, data on morbidity, mortality, discharge location, hospital readmissions within one year, and freedom from reoperation were obtained.
Compared to ST, MIMVS was associated with a $9,054 ± 3,302 lower mean total hospital cost (p=0.006), driven largely by a reduction in direct (p=0.003) versus indirect costs (p=0.06). Among the 13 billing categories, MIMVS was associated with a significant reduction in costs of: cardiac imaging (p=0.004), laboratory tests (p=0.005), boarding and nursing (p=0.001), and radiology (p=0.002). More patients in the ST group required intubation for > 72 hours (p=0.019); however, there were no differences in morbidity or long-term survival (p=0.334). There were a higher proportion of MI patients discharged home with no nursing services (p=0.018), and a higher proportion of readmissions among ST patients within one year (p=0.023). There were no differences in freedom from reoperation between groups (p=0.574).
With equivalent efficacy across a range of measures and lower costs compared to ST, MIMVS represents a cost-saving strategy for MVS.
PMCID: PMC3182301  PMID: 21665228
20.  Long-Term Mortality of Coronary Artery Bypass Graft Surgery and Bare-Metal Stenting 
The Annals of Thoracic Surgery  2011;92(6):2132-2138.
There is little information on the relative survival of coronary artery bypass graft (CABG) surgery and percutaneous coronary intervention with stenting with follow-up longer than 5 years. This study tested the hypothesis that CABG surgery is associated with lower risk of long-term (8-year) mortality than stenting with bare-metal stents for multivessel coronary disease.
We identified 18,359 patients with multivessel disease who underwent isolated CABG surgery and 13,377 patients who received BMS in 1999–2000 in New York, and followed their vital status through 2007 using the National Death Index. We matched CABG and stent patients on the number of diseased coronary vessels, proximal left anterior descending (LAD) artery disease, and propensity of undergoing CABG surgery based on numerous patient characteristics, and compared the survival after the two procedures.
In the 7,235 pairs of matched patients, the overall 8-year survival rates were 78.0% for CABG surgery and 71.2% for stenting (hazard ratio = 0.68, 95% confidence interval: 0.64 to 0.74, P<0.001). For anatomic groups classified by the number of diseased vessels and proximal LAD involvement, the hazard ratios ranged from 0.53 (P<0.001) for patients with 3-vessel disease involving proximal LAD artery disease to 0.78 (P=0.05) for patients with 2-vessel disease but no disease in the LAD artery. A lower risk of death after CABG surgery was observed in all subgroups stratified by a number of baseline risk factors.
CABG surgery is associated with lower risk of death than stenting with bare-metal stents for multivessel coronary disease.
PMCID: PMC3271851  PMID: 22014747
Coronary artery bypass grafts; Coronary percutaneous interventions; Outcomes
21.  Comparative Composition, Diversity and Trophic Ecology of Sediment Macrofauna at Vents, Seeps and Organic Falls 
PLoS ONE  2012;7(4):e33515.
Sediments associated with hydrothermal venting, methane seepage and large organic falls such as whale, wood and plant detritus create deep-sea networks of soft-sediment habitats fueled, at least in part, by the oxidation of reduced chemicals. Biological studies at deep-sea vents, seeps and organic falls have looked at macrofaunal taxa, but there has yet to be a systematic comparison of the community-level attributes of sediment macrobenthos in various reducing ecosystems. Here we review key similarities and differences in the sediment-dwelling assemblages of each system with the goals of (1) generating a predictive framework for the exploration and study of newly identified reducing habitats, and (2) identifying taxa and communities that overlap across ecosystems. We show that deep-sea seep, vent and organic-fall sediments are highly heterogeneous. They sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist (heterotrophic and symbiont-associated) and background fauna. Community-level comparisons reveal that vent, seep and organic-fall macrofauna are very distinct in terms of composition at the family level, although they share many dominant taxa among these highly sulphidic habitats. Stress gradients are good predictors of macrofaunal diversity at some sites, but habitat heterogeneity and facilitation often modify community structure. The biogeochemical differences across ecosystems and within habitats result in wide differences in organic utilization (i.e., food sources) and in the prevalence of chemosynthesis-derived nutrition. In the Pacific, vents, seeps and organic-falls exhibit distinct macrofaunal assemblages at broad-scales contributing to ß diversity. This has important implications for the conservation of reducing ecosystems, which face growing threats from human activities.
PMCID: PMC3319539  PMID: 22496753
22.  The golden age of minimally invasive cardiothoracic surgery: current and future perspectives 
Future cardiology  2011;7(3):333-346.
Over the past decade, minimally invasive cardiothoracic surgery (MICS) has grown in popularity. This growth has been driven, in part, by a desire to translate many of the observed benefits of minimal access surgery, such as decreased pain and reduced surgical trauma, to the cardiac surgical arena. Initial enthusiasm for MICS was tempered by concerns over reduced surgical exposure in highly complex operations and the potential for prolonged operative times and patient safety. With innovations in perfusion techniques, refinement of transthoracic echocardiography and the development of specialized surgical instruments and robotic technology, cardiac surgery was provided with the necessary tools to progress to less invasive approaches. However, much of the early literature on MICS focused on technical reports or small case series. The safety and feasibility of MICS have been demonstrated, yet questions remain regarding the relative efficacy of MICS over traditional sternotomy approaches. Recently, there has been a growth in the body of published literature on MICS long-term outcomes, with most reports suggesting that major cardiac operations that have traditionally been performed through a median sternotomy can be performed through a variety of minimally invasive approaches with equivalent safety and durability. In this article, we examine the technological advancements that have made MICS possible and provide an update on the major areas of cardiac surgery where MICS has demonstrated the most growth, with consideration of current and future directions.
PMCID: PMC3134935  PMID: 21627475
minimally invasive cardiothoracic surgery; outcomes
23.  Submarine canyons: hotspots of benthic biomass and productivity in the deep sea 
Submarine canyons are dramatic and widespread topographic features crossing continental and island margins in all oceans. Canyons can be sites of enhanced organic-matter flux and deposition through entrainment of coastal detrital export, dense shelf-water cascade, channelling of resuspended particulate material and focusing of sediment deposition. Despite their unusual ecological characteristics and global distribution along oceanic continental margins, only scattered information is available about the influence of submarine canyons on deep-sea ecosystem structure and productivity. Here, we show that deep-sea canyons such as the Kaikoura Canyon on the eastern New Zealand margin (42°01′ S, 173°03′ E) can sustain enormous biomasses of infaunal megabenthic invertebrates over large areas. Our reported biomass values are 100-fold higher than those previously reported for deep-sea (non-chemosynthetic) habitats below 500 m in the ocean. We also present evidence from deep-sea-towed camera images that areas in the canyon that have the extraordinary benthic biomass also harbour high abundances of macrourid (rattail) fishes likely to be feeding on the macro- and megabenthos. Bottom-trawl catch data also indicate that the Kaikoura Canyon has dramatically higher abundances of benthic-feeding fishes than adjacent slopes. Our results demonstrate that the Kaikoura Canyon is one of the most productive habitats described so far in the deep sea. A new global inventory suggests there are at least 660 submarine canyons worldwide, approximately 100 of which could be biomass hotspots similar to the Kaikoura Canyon. The importance of such deep-sea canyons as potential hotspots of production and commercial fisheries yields merits substantial further study.
PMCID: PMC2981985  PMID: 20444722
submarine canyons; benthic biomass hotspots; molpadiid holothurians; macrourid fishes; eastern New Zealand margin
24.  Man and the Last Great Wilderness: Human Impact on the Deep Sea 
PLoS ONE  2011;6(8):e22588.
The deep sea, the largest ecosystem on Earth and one of the least studied, harbours high biodiversity and provides a wealth of resources. Although humans have used the oceans for millennia, technological developments now allow exploitation of fisheries resources, hydrocarbons and minerals below 2000 m depth. The remoteness of the deep seafloor has promoted the disposal of residues and litter. Ocean acidification and climate change now bring a new dimension of global effects. Thus the challenges facing the deep sea are large and accelerating, providing a new imperative for the science community, industry and national and international organizations to work together to develop successful exploitation management and conservation of the deep-sea ecosystem. This paper provides scientific expert judgement and a semi-quantitative analysis of past, present and future impacts of human-related activities on global deep-sea habitats within three categories: disposal, exploitation and climate change. The analysis is the result of a Census of Marine Life – SYNDEEP workshop (September 2008). A detailed review of known impacts and their effects is provided. The analysis shows how, in recent decades, the most significant anthropogenic activities that affect the deep sea have evolved from mainly disposal (past) to exploitation (present). We predict that from now and into the future, increases in atmospheric CO2 and facets and consequences of climate change will have the most impact on deep-sea habitats and their fauna. Synergies between different anthropogenic pressures and associated effects are discussed, indicating that most synergies are related to increased atmospheric CO2 and climate change effects. We identify deep-sea ecosystems we believe are at higher risk from human impacts in the near future: benthic communities on sedimentary upper slopes, cold-water corals, canyon benthic communities and seamount pelagic and benthic communities. We finalise this review with a short discussion on protection and management methods.
PMCID: PMC3148232  PMID: 21829635
25.  Low Pressure Vinylation of Aryl and Vinyl Halides via Heck-Mizoroki Reactions Using Ethylene 
Tetrahedron  2010;66(5):1102-1110.
Aryl bromides and iodides in the presence of catalytic amounts of a palladacycle derived from acetophenone oxime and 2 equivalents of potassium acetate react with ethylene under ambient pressure (15–30 psi) to give the corresponding vinylarenes. The reactions work with both electron-deficient and electron-rich aryl compounds and tolerate wide variety of common functional groups. Vinyl bromides lead to 1,3-dienes in moderate yields.
PMCID: PMC2910319  PMID: 20676383

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