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Background Surgeons perform emergent exploratory laparotomies (ex-laps) for a myriad of surgical diagnoses. We characterized common diagnoses for which emergent ex-laps were performed and leveraged these groups to improve risk-adjustment models for postoperative mortality. Methods Using American Association for the Surgery of Trauma criteria, we identified hospitalizations where the primary procedure was an emergent ex-lap in the 2012 to 2014 (derivation cohort) and 2015 (validation cohort) Nationwide Inpatient Sample. After tabulating all International Classification of Diseases-9th Rev.-Clinical Modification diagnosis codes within these hospitalizations, we divided them into clinically relevant groups. Using two stepwise regression paradigms-forward selection and backward elimination-we identified diagnostic groups significantly associated with postoperative mortality in multivariable logistic regressions. We evaluated the addition of these groups as individual covariates in risk-adjustment models for postoperative mortality using the area under the receiver operator characteristic curve. All regressions additionally adjusted for clinical factors and hospital clustering. Results We identified 4127 patients in the derivation cohort (median age, 50 years; 46.0% female; 62.1% white), with an overall mortality rate of 13.4%. Among all patients, we tabulated a total of 164 diagnosis codes, of which 27 (16.5%) may have led to an emergent ex-lap. These 27 codes clinically represented seven diagnostic categories, which captured a majority of the patients (70.4%). Backward elimination and forward selection led to four common diagnosis categories associated with mortality: bleeding, obstruction, shock, and ischemia. Adjusting for these four diagnostic groups in a multivariable logistic regression assessing postoperative mortality increased the area under the receiver operator characteristic curve from 74.5% to 88.2% in the derivation cohort and from 73.8% to 88.2% in the validation cohort. Conclusion Seven diagnostic groups account for the majority of the emergent ex-laps. Adjusting for four groups may improve the accuracy of risk-adjustment models for mortality and validating such analytic standardization may optimize best research practices for EGS procedures. Level of evidence Prognostic and epidemiologic, Level III.

Background Hospital variation in failure-to-rescue (FTR) rates has partially explained nationwide differences in mortality after elective surgeries. To examine the role of FTR among emergency general surgery, we compared nationwide risk-adjusted mortality, complications, and FTR rates after emergent bowel resections. Methods We identified patients who underwent emergent small or large bowel resections in the 2010 to 2011 Nationwide Inpatient Sample using the American Association for the Surgery of Trauma criteria. We then calculated risk-adjusted mortality rates for each hospital using multivariable logistic regressions and postestimation, which adjusted for patient age, sex, race and ethnicity, payer status, comorbidities, and hospital clustering. After excluding hospitals with fewer than 10 resections per year, we ranked the remaining hospitals by their risk-adjusted mortality rates and divided them into five quintiles. We compared both risk-adjusted complication rates and FTR rates between the top (lowest mortality) and bottom (highest mortality) quintiles. Results We identified 21,564 emergent bowel resections, weighted to 105,925 procedures nationwide. The bottom quintile of hospitals had an overall risk-adjusted mortality rate that was 10.9 times higher than that of the top quintile of hospitals (15.3% vs. 1.4%). While risk-adjusted complication rates were similarly high for both the bottom and the top quintiles of hospitals (22.5% vs. 15.7%), the risk-adjusted FTR rates were 10.8 times higher in the bottom quintile of hospitals relative to the top quintile of hospitals (33.4% vs. 3.1%). Using larger hospital volume thresholds yielded similar findings. Furthermore, large variations existed in complication-specific FTR rates (surgical site infection [6.6%] to myocardial infarction [29.4%]). Conclusion Nationwide hospital variation in risk-adjusted mortality rates exist after emergent bowel resections. As complication rates were similar across hospitals, the significantly higher FTR rates at higher-mortality hospitals may drive this variation in mortality. System-level initiatives addressing the management of postoperative complications may improve patient care and reduce variation in outcomes. Level of evidence Prognostic and epidemiological study, level IV.

Background Patients and hospitals face significant financial burdens from emergency general surgeries (EGSs), which have been termed a public health crisis in the United States. We evaluated hospitalization charges, operating charges, and variations in operating time by surgeon volume for three common EGS procedures. Methods Using Maryland's Health Services Cost Review Commission database, we performed a retrospective study of laparoscopic appendectomies, laparoscopic cholecystectomies, and open bowel resections performed by general surgeons among adult patients from July 2012 to September 2014. We compared operating charges to total hospitalization charges and quantified variations in operating time for each procedure. We then divided patients into quartiles based on their surgeon's procedure-specific case volume and used hierarchical linear regressions to calculate differences in both operating time and charges between quartiles. Results We identified 3194 appendectomies, 4143 cholecystectomies, and 1478 bowel resections. Operating charges accounted for one-quarter (26.9%) of total hospitalization charges and widespread variation existed in operating time (appendectomies: median 79 min [interquartile range 66-100 min], cholecystectomies: 96 min [76-125 min], bowel resections: 155 min [117-209 min]). After adjustment, low-volume surgeons relative to high-volume surgeons did not operate statistically longer for appendectomies (+1%, 95% confidence interval [CI]: −2% to 5%) but operated +16% (95% CI: 12%-20%) longer for cholecystectomies (+14 min) and +40% (95% CI: 30%-50%) longer for bowel resections (+59 min). Adjusted median operating charges from low-volume surgeons relative to high-volume surgeons were $554 (26.7%), $621 (22.0%), and $1801 (47.0%) greater for appendectomies, cholecystectomies, and bowel resections, respectively. Conclusions Operating charges contributed substantially to total EGS hospitalization charges, where low-volume surgeons operated longer and had higher operative charges relative to high-volume surgeons. Reducing variations in operating times and charges represents an opportunity to alleviate the financial burden from EGS procedures.

Background Neonatal mesenchymal stem cells exhibit less cardioprotective potential than their adult counterparts. Transforming growth factor-α (TGF-α) has been shown to stimulate adult stem cell VEGF production, however, it remains unknown whether it may augment neonatal stem cell paracrine function. We hypothesized that TGF-α would equalize adult and neonatal stem cell paracrine function and cardioprotection during acute ischemia/reperfusion. Materials and Methods Bone marrow mesenchymal stem cells isolated from adult and 2.5 wk-old mice were treated with TGF-α (250 ng/mL) for 24 h. VEGF, HGF, IGF-1, IL-1β, and IL-6 production were measure in vitro , and cells were infused via an intracoronary route using a model of isolated heart perfusion. Results TGF-α equalized adult and neonatal stem cell VEGF production but did not affect production of HGF, IGF-1, IL-1β, or IL-6. ERK, p38 MAPK, and JNK phosphorylation were greater in adult cells in response to TGF-α. Whereas infusion of adult but not neonatal stem cells was associated with improved myocardial functional recovery during reperfusion, infusions of either TGF-α-pretreated cell group were associated with the greatest functional recovery. TGF-α equalizes adult and neonatal mesenchymal stem cell VEGF production and cardioprotection in association with differential regulation of ERK, p38 MAPK, and JNK phosphorylation.

Background Mesenchymal stem cells (MSCs) improve postischemic myocardial function in part through their secretion of growth factors such as vascular endothelial growth factor (VEGF). Pretreating MSCs with various cytokines or small molecules can improve VEGF secretion and MSC-mediated cardioprotection. However, whether 1 cytokine can potentiate the effect of another cytokine in MSC pretreatment to achieve a synergistic effect on VEGF production and cardioprotection is poorly studied. Methods MSCs were treated with interleukin (IL)-1β and/or transforming growth factor (TGF)-β1 for 24 hours before experiments. VEGF production was determined by enzyme-linked immunosorbent assay. Isolated hearts from adult male Sprague-Dawley rats were subjected to 15 minutes of equilibration, 25 minutes of ischemia, and 40 minutes reperfusion. Hearts ( n = 5–7 per group) were randomly infused with vehicle, untreated MSCs, or MSCs pretreated with IL-1β and/or TGF-β1. Specific inhibitors were used to delineate the roles of p38 mitogen-activated protein kinase (MAPK) and SMAD3 in IL-1β– and TGF-β1–mediated stimulation of MSCs. Results MSCs cotreated with IL-1β and TGF-β1 exhibited synergistically increased VEGF secretion, and they greatly improved postischemic myocardial functional recovery. Ablation of p38 MAPK and SMAD3 activation with specific inhibitors negated both IL-1β– and TGF-β1–mediated VEGF production in MSCs and the ability of these pretreated MSCs to improve myocardial recovery after ischemia. Conclusion Pretreating MSCs with 2 cytokines may be useful to fully realize the potential of cell-based therapies for ischemic tissues.

Background Sepsis remains a source of morbidity and mortality in the postoperative patient despite appropriate resuscitative and antimicrobial approaches. Recent research has focused upon additional interventions such as exogenous cell-based therapy. Mesenchymal stem cells (MSCs) exhibit multiple beneficial properties through their capacity for homing, attenuating the inflammatory response, modulating immune cells, and promoting tissue healing. Recent animal trials have provided evidence that MSCs may be useful therapeutic adjuncts. Materials and Methods A directed search of recent medical literature was performed utilizing PubMed to examine the pathophysiology of sepsis, mechanisms of mesenchymal stem cell interaction with host cells, sepsis animal models, and recent trials utilizing stem cells in sepsis. Results MSCs continue to show promise in the treatment of sepsis by their intrinsic ability to home to injured tissue, secrete paracrine signals to limit systemic and local inflammation, decrease apoptosis in threatened tissues, stimulate neoangiogenesis, activate resident stem cells, beneficially modulate immune cells, and exhibit direct antimicrobial activity. These effects are associated with reduced organ dysfunction and improved survival in animal models. Conclusion Research utilizing animal models of sepsis has provided a greater understanding of the beneficial properties of MSCs. Their capacity to home to sites of injury and use paracrine mechanisms to change the local environment to ultimately improve organ function and survival make MSCs attractive in the treatment of sepsis. Future studies are needed to further evaluate the complex interactions between MSCs and host tissues.

Background Cardiac surgery induces the release of inflammatory mediators that can prolong cardiac dysfunction after operative intervention. Interleukin-10 (IL-10), a potent inhibitor of myocardial inflammation, is a known factor in myocardial protection after ischemia/reperfusion (I/R) injury. We hypothesized that IL-10 activity during initial reperfusion is mediated through the signal transducer and activator of transcription 3 (STAT3) pathway. Methods Adult rat hearts were isolated and perfused via Langendorff protocol and subjected to global I/R. After determining the effective IL-10 dose, hearts were administered vehicle, IL-10, or IL-10 + Stattic (specific STAT3 inhibitor) 1 min prior to ischemia. After reperfusion, hearts were sectioned and assessed for levels of myocardial inflammatory cytokines and protein. Results The IL-10 minimum effective dose was 1 μg. IL-10-treated hearts had improved markedly myocardial function after global I/R compared to both vehicle and IL-10 + Stattic groups. In addition, IL-10 treatment was associated with a significant decrease in myocardial interleukin-1β (IL-1β) and interleukin-6 (IL-6) and increase in myocardial IL-10. Myocardial STAT3 was elevated markedly in IL-10 treated hearts. Conclusion IL-10 improves myocardial function after acute global I/R and suppresses inflammation through the STAT3 pathway. The administration of anti-inflammatory agents may have potential therapeutic applications in cardiac surgery.

Mesenchymal stem cells (MSCs) have been used experimentally and clinically in the treatment of a wide variety of pathologies. It is now clear that a number of different mechanisms contribute to the therapeutic effects exerted by these cells. The ability of MSCs to interact with and modulate the functions of a wide variety of immune cells has been recognized as one such mechanism. The implications that the immunomodulatory properties of MSCs may have for the treatment of solid organ rejection, the Systemic Inflammatory Response Syndrome, cancer, and Crohn’s disease are reviewed herein.

Background Stem cell-based therapies for myocardial ischemia have demonstrated promising early clinical results, but their benefits have been limited in duration due to impaired donor cell engraftment and function. Several strategies have emerged for enhancing stem cell function prior to their therapeutic use particularly with regard to stem cell homing, paracrine function, and survival. This review discusses current understandings of stem cell-mediated cardioprotection as well as methods of enhancing post-transplantation stem cell function and survival through hypoxic preconditioning, genetic manipulation, and pharmacologic pretreatment. Materials and Methods A literature search was performed using the MEDLINE and PubMed databases using the keywords “stem cell therapy,” “myocardial ischemia,” “hypoxic preconditioning,” “paracrine function,” and “stem cell pretreatment.” Studies published in English since January 1990 were selected. In addition, studies were identified from references cited in publications found using the search terms. Results All included studies utilized animal studies and/or in vitro techniques. Stem cell modifications generally targeted stem cell homing (SDF-1, CXCR4), paracrine function (VEGF, angiogenin, Ang-1, HGF, IL-18 binding protein, TNFR1/2), or survival (Akt, Bcl-2, Hsp20, HO-1, FGF-2). However, individual modifications commonly exhibited pleiotropic effects involving some or all of these general categories. Conclusion These strategies for optimizing stem cell-mediated cardioprotection present unique potential sets of advantages and disadvantages for clinical application. Additional questions remain including those that are most efficacious in terms of magnitude and duration of benefit as well as whether combinations may yield greater benefits in both the preclinical and clinical settings.

Atrial fibrillation (AF) is the most common chronic arrhythmia in the United States and is associated with high morbidity rates and significant healthcare costs. Although medical therapy for AF modestly reduces complications, cardiac surgery continues to have an important role in the treatment of AF and is constantly evolving. Cardiothoracic surgeons are uniquely positioned to offer effective operations to patients with lone AF, in addition to those undergoing concomitant elective cardiac surgery. This review discusses (1) the burden of AF, (2) classification and electrophysiology of AF, (3) surgical techniques and outcomes, and (4) future directions in surgical therapy.

Background Endotoxemia is associated with depressed cardiac function during sepsis. Mesenchymal stem cells (MSCs) possess an ability to modulate the inflammatory response during sepsis, but it is unknown whether MSCs possess the ability to reduce endotoxemia-induced myocardial injury and dysfunction. Methods Endotoxemia was induced in rats via injection of lipopolysaccharide (LPS). Animals were divided into the following groups: (1) saline + saline; (2) LPS + saline; (3) LPS + MSCs; and (4) LPS + LLC-PK1 renal epithelial cells (differentiated control). At 6 hours, animals were anesthetized, serum was collected, and hearts were extracted and perfused via the isolated heart system. Hearts and serum were analyzed for tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10. Results The administration of LPS depressed myocardial function. Treatment with MSCs ameliorated this depression. Serum TNF-α, IL-1β, and IL-6 were elevated in LPS-treated groups. Treatment with MSCs was associated with reduced levels of these cytokines. A trend toward reduced myocardial TNF-α and significant reductions in myocardial IL-1β and IL-6 were observed in the MSC-treated group. IL-10 levels were increased after the LPS administration in both serum and myocardium. Serum levels were increased further after treatment with MSCs. Conclusion Treatment with MSCs during endotoxemia reduces systemic and myocardial inflammation and is associated with a reduction in LPS-induced myocardial functional depression.

Estrogen may protect against the development of cardiovascular disease. Recently, a receptor known as GPR30 that seems to mediate estrogen's nongenomic effects has been identified. We hypothesized that the activation of GPR30 protects cardiac function and decreases myocardial inflammation after global ischemia/reperfusion (I/R).Hearts from male Sprague-Dawley rats were perfused via Langendorff and treated with either (1) vehicle; (2) 10 nm of the GPR30 agonist, G-1; or (3) 100 nm of G-1; they then were subjected to 25 minutes of ischemia and 40 minutes of reperfusion. Cardiac functional parameters were measured continuously. Ventricular tissue was analyzed for tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6.At end-reperfusion, the left ventricular developed pressure in the 100-nm G-1 group was improved compared with vehicle (26% +/- 12% equilibrium vs 54% +/- 9% equilibrium; P.05). Similar findings were noted when comparing the 100-nm G-1 group with the vehicle in terms of +dP/dt (53% +/- 12% equilibrium vs 26% +/- 19%, respectively; P.05) and -dP/dt (56% +/- 15% equilibrium vs 22% +/- 16% equilibrium, respectively; P.05). TNF-alpha, IL-1beta, and IL-6 levels were lower in myocardium of the 100-nm G-1 group compared with the vehicle (P.05).The GPR30 agonist, G-1, improves functional recovery and decreases myocardial inflammation after global I/R. GPR30 may play an important role in estrogen's ability to protect the heart against I/R injury.

Background Transforming growth factor-α (TGF-α) has been shown to augment mesenchymal stem cell-mediated cardioprotection during acute ischemia and reperfusion in isolated heart models. To determine whether this pretreatment strategy would be effective in vivo, we hypothesized that the intramyocardial injection of mesenchymal stem cells pretreated with TGF-α after coronary artery ligation would confer greater preservation of cardiac function, reduction in infarct size, and reduction myocardial inflammation. Methods Sprague-Dawley rats underwent left anterior descending coronary artery ligation. Ischemic border zones were injected 30 minutes later with vehicle (n = 11), 1 million mesenchymal stem cells (n = 9), or mesenchymal stem cells pretreated with TGF-α (250 ng/mL for 24 hours; n=10). Cardiac function was assessed by echocardiography at 7 and 28 days after ligation. Infarct size was measured using triphenyltetrazolium chloride. Ischemic border zone cytokine expression was measured 30 days after infarction. Results Myocardial function after ligation was greatest in hearts injected with cells pretreated with TGF-α in association with reduced ventricular remodeling and infarct size compared with vehicle-injected hearts. Myocardial interleukin 1β, interleukin 6, and TNF-α concentrations were lower, and Bcl-2 expression was higher, in hearts injected with either cell type. Vascular endothelial growth factor and matrix metalloproteinase-2 expression were highest in hearts that received pretreated cells. Conclusions Intramyocardial injection of mesenchymal stem cells pretreated with TGF-α further protects cardiac function and reduces infarct size compared with injection of untreated cells. Pretreating donor cells with TGF-α may be useful for enhancing cell-based therapies for myocardial ischemia.

Background The activation of the epidermal growth factor family of receptors may improve cardiac protection after injury. One epidermal growth factor family ligand, transforming growth factor-alpha, promotes wound healing in multiple tissues in response to oxidative injury and might confer resistance to myocardial depressant factors, although the role of transforming growth factor-alpha in myocardial ischemia/reperfusion injury is unknown. We hypothesized that preischemic infusion of transforming growth factor-alpha would improve myocardial functional recovery after acute ischemia/reperfusion. Methods The hearts from adult male rats were isolated and perfused via the Langendorff model. Immediately prior to ischemia, the hearts received an intracoronary infusion of either vehicle or transforming growth factor-alpha (1 ng, 10 ng, or 100 ng). After reperfusion, the hearts were assessed for activation of the prosurvival pathway, Akt. Results Infusion of transforming growth factor-alpha did not confer any additional functional protection compared with the vehicle, but myocardial tissue analysis revealed significantly increased activation of the Akt pathway in both the 10-ng and 100-ng groups. Conclusion Preischemic infusion of transforming growth factor-alpha does not improve myocardial functional recovery after ischemia/reperfusion injury. Whereas transforming growth factor-alpha treatment does affect actions at the molecular level, these actions do not translate into an observable functional effect. This lack of improvement may point to a relative unimportance of transforming growth factor-alpha in myocardial signaling compared with other epidermal growth factor ligands.

Background Stem cells protect the heart from ischemic damage in part by the release of cytoprotective growth factors, particularly vascular endothelial growth factor (VEGF). Production of VEGF is regulated in part by levels of the transcription factor hypoxia inducible factor 1-α (HIF-1α). Dimethyloxalylglycine (DMOG) prevents the deactivation of HIF-1α and increases VEGF production. However, the effects of systemic DMOG treatment on myocardial tolerance for ischemia are unknown. We hypothesized that systemic pretreatment with DMOG would improve myocardial ischemic tolerance. Methods To study this hypothesis, adult male rats were randomly given an intraperitoneal injection of DMOG (40 mg/kg in 1 mL saline, n = 5) or saline (1 mL, n = 6) 24 h before cardiectomy and isolated heart perfusion. All hearts were subjected to 15 min equilibration, 25 min ischemia and 40 min reperfusion. Myocardial function was continuously monitored. Following reperfusion, myocardial homogenates were analyzed for HIF-1α and VEGF production. Results We observed that hearts in the DMOG group exhibited greater recovery of left ventricular developed pressure LVDP, +dP/dt and −dP/dt. Myocardial HIF-1α and VEGF levels were increased by DMOG therapy. Conclusion In conclusion, systemic pretreatment with DMOG augments post-ischemic myocardial functional recovery through increased HIF-1α levels and greater VEGF production.

Background Signal transducer and activator of transcription 3 (STAT3) regulates myocardial apoptosis, cellular proliferation, and the immune response after ischemia/reperfusion (I/R). STAT3 is also necessary for the production of vascular endothelial growth factor (VEGF) by mesenchymal stem cells (MSCs), which are known to reduce myocardial injury after I/R. However, it remains unknown whether STAT3 is an important mediator of MSC-based cardioprotection. We hypothesized that knockout of stem cell STAT3 would reduce MSC-derived myocardial functional recovery and increase myocardial inflammatory and apoptotic signaling. Study Design With a Langendorff apparatus, male rat hearts were subjected to 15 minutes of equilibration and 25 minutes of ischemia, followed by 40 minutes of reperfusion. Immediately before ischemia, hearts received intracoronary infusions of vehicle, wild-type MSCs (WT MSCs) or STAT3 knockout MSCs (STAT3KO MSCs). Heart function was measured continuously. Myocardial homogenates were analyzed for production of interleukin (IL)-1, IL-6, and tumor necrosis factor-α (TNF-α). Additionally, MSC production of hepatocyte growth factor (HGF) and insulin-like growth factor-1 (IGF-1) were measured in vitro. Results Hearts treated with WT MSCs exhibited the greatest functional recovery, and those treated with STAT3KO MSCs had equivalent recovery to vehicle. The highest proinflammatory cytokine levels were seen in vehicle-treated hearts, and the lowest in the WT MSC group. STAT3KO MSCs produced less IGF-1, but more HGF than WT MSCs. Finally, hearts treated with STAT3KO MSCs or vehicle had significantly higher caspase-3 levels than those treated with WT MSCs. Conclusions Intracoronary infusions of MSCs improve postischemic left ventricular function and reduce proapoptotic and proinflammatory signaling via a STAT3-dependent mechanism.

Background High-mobility group box 1 (HMGB1) is a mediator of inflammation with dose-dependent effects. In the setting of regional myocardial infarction, a high-dose HMGB1 treatment decreases myocardial function, whereas low-dose HMGB1 improves function; however, it is unknown what role HMGB1 has in the setting of global ischemia/reperfusion (I/R) injury. We hypothesized that a low-dose HMGB1 treatment would improve myocardial functional recovery and decrease infarct size after global I/R injury in association with increased levels of cardioprotective paracrine factors and decreased inflammation. Methods Adult rat hearts were isolated and perfused using the Langendorff method and were subjected to global I/R and treatment with either the vehicle, 200-ng HMGB1, or 1-μg HMGB1. The treatment was administered during 1 min at the start of reperfusion, and myocardial function was measured for 60 min of reperfusion. At the end of reperfusion, the hearts were sectioned and incubated in triphenyltetrazolium chloride to assess myocardial infarct size or homogenized to measure levels of inflammatory cytokines and growth factors. Results Postischemic treatment with 200-ng HMGB1 significantly improved myocardial functional recovery after global I/R in association with decreased infarct size and decreased interleukin-1 (IL-1), IL-6, IL-10, and vascular endothelial growth factor (VEGF) levels. In addition, 1-μg HMGB1 decreased myocardial inflammation but did not result in subsequent improvement in functional recovery. Conclusion In the setting of global I/R, 200-ng postischemic HMGB1 treatment improves myocardial function and decreases infarct size in association with suppressed myocardial inflammation. These results suggest a potential role for exogenous HMGB1therapy in the acute postischemic period.