Postoperative atrial fibrillation (POAF) after cardiac surgery: clinical practice review.

Postoperative atrial fibrillation (POAF) after cardiac surgery is associated with elevated morbidity and mortality. Although current prediction models have limited efficacy, several perioperative interventions can reduce patients' risk of POAF. These begin with preoperative medications, including beta-blockers and amiodarone. Moreover, patients should be screened for preexisting atrial fibrillation (AF) so that concomitant surgical ablation and left atrial appendage occlusion can be performed in appropriate candidates. Intraoperative interventions such as posterior pericardiectomy can reduce mediastinal fluid accumulation, which is a trigger for POAF. Furthermore, many preventive strategies for POAF are implemented in the immediate postoperative period. Initiating beta-blockers, amiodarone, or both is reasonable for most patients. Overdrive atrial pacing, colchicine, and steroids have been used by some, although the evidence base is less robust. For patients with POAF, rate-control and rhythm-control strategies have comparable outcomes. Decision-making regarding anticoagulation should recognize that the stroke risk associated with POAF appears to be lower than that for general nonvalvular AF. The evidence that oral anticoagulation reduces stroke risk is less clear for POAF patients than for patients with general nonvalvular AF. Given that POAF tends to be shorter-lived and is associated with greater bleeding risks in the perioperative period, decisions regarding anticoagulation should be individualized. Finally, wearable technology and machine learning algorithms for better predicting and managing POAF appear to be coming soon. These technologies and a comprehensive clinical program could meaningfully reduce the incidence of this common complication.

Medical Therapy After CABG: the Known Knowns, the Known Unknowns, and the Unknown Unknowns.

PURPOSE: Medical therapies play a central role in secondary prevention after surgical revascularization. While coronary artery bypass grafting is the most definitive treatment for ischemic heart disease, progression of atherosclerotic disease in native coronary arteries and bypass grafts result in recurrent adverse ischemic events. The aim of this review is to summarize the recent evidence regarding current therapies in secondary prevention of adverse cardiovascular outcomes after CABG and review the existing recommendations as they pertain to the CABG subpopulations. RECENT FINDINGS: There are many pharmacologic interventions recommended for secondary prevention in patients after coronary artery bypass grafting. Most of these recommendations are based on secondary outcomes from trials which include but did not focus on surgical patients as a cohort. Even those designed with CABG in mind lack the technical and demographic scope to provide universal recommendations for all CABG patients. CONCLUSION: Recommendations for medical therapy after surgical revascularization are chiefly based on large-scale randomized controlled trials and meta-analyses. Much of what is known about medical management after surgical revascularization results from trials comparing surgical to non-surgical approaches and important characteristics of the operative patients are omitted. These omissions create a group of patients who are relatively heterogenous making solid recommendations elusive. While advances in pharmacologic therapies are clearly adding to the armamentarium of options for secondary prevention, knowing what patients benefit most from each therapeutic option remains challenging and a personalized approach is still required.

Current approaches to spinal cord protection during open thoracoabdominal aortic aneurysm repair.

Spinal cord deficit (SCD) is a feared complication after thoracoabdominal aortic aneurysm repair. Vigilant management throughout the perioperative period is necessary to reduce the risk of SCD. Measures for preventing SCD during the intraoperative period include preoperative optimization and recognizing patients at a higher risk of SCD. In this manuscript, we discuss intraoperative adjuncts including utilization of cerebrospinal fluid drainage, left heart bypass, mild hypothermia, selective reimplantation of intercostal and lumbar arteries, and renal and visceral vessel perfusion. From the operative to the postoperative period, careful attention to avoiding hypotension and anemia is important. If SCD is recognized early, therapeutic intervention may be implemented to mitigate injury.

Performance of an Irrigated Bipolar Radiofrequency Ablation Clamp on Explanted Human Hearts.

BACKGROUND: Bipolar radiofrequency (RF) clamps are commonly used during surgical ablation for atrial fibrillation (AF). This study examined the efficacy of an irrigated bipolar RF clamp to create transmural lesions in an ex vivo human heart model. METHODS: Ten donor hearts, turned down for transplantation, were explanted and arrested with cold cardioplegia. The ablations of the Cox Maze IV procedure were performed using the Cardioblate LP (Medtronic, Inc) irrigated bipolar RF clamp. In the first 5 hearts, each lesion was created with a single application of RF, whereas in the remaining 5 hearts, each lesion was created with a double application of RF without unclamping. Each lesion was cross-sectioned and stained with 2,3,5-triphenyl-tetrazolium chloride to assess ablation depth and transmurality. RESULTS: A total of 100 lesions were analyzed. In the single-ablation group, 222 of 260 sections (85%) and 37 of 50 lesions (74%) were transmural. The efficacy improved significantly in the double-ablation group, in which 348 of 359 sections (97%, P < .001) and 46 of 50 lesions (92%, P = .017) were transmural. Overall, in nontransmural lesions, the epicardial fat thickness was significantly greater (1.69 ± 0.70 mm vs 0.45 ±0.10 mm, P < .001) than the transmural lesions. CONCLUSIONS: A single ablation on human atrial tissue with an irrigated bipolar RF clamp was insufficient to reliably create transmural lesions, but a double ablation significantly increased the lesion and section transmurality. Nontransmural lesions were associated with significantly thicker layers of epicardial fat, which likely decreased tissue energy delivery due to the higher resistance of fat to current flow.

Impact of autonomic regulation on burnout and performance in thoracic surgery residents.

Objective: This study sought to determine the feasibility of collecting physiologic data in thoracic surgery residents and whether it would correlate with burnout and burnout with performance. Methods: This was a prospective study of thoracic surgery residents over a 5-month period. Participants were evaluated with a wearable biometric device (heart rate variability and sleep) and the Maslach Burnout Inventory. Resident performance was quantified using Accreditation Council for Graduate Medical Education Milestones (scale, 1-5) normalized to program-designated targets (3 for postgraduate year 6 or lower residents and 4 for postgraduate year 7 residents). Results: The cohort consisted of 71% female participants (5/7) with 86% of residents having 1 or more children. High levels of emotional exhaustion (median, 30 [interquartile range, 20-36], where >26 is high) and high levels of depersonalization (median, 16 [interquartile range, 14-22], where >12 is high) were common, but personal accomplishment was also uniformly high (median, 43 [interquartile range, 41-46], where >38 is high). There was a significant correlation between heart rate variability and emotional exhaustion (r(12) = 0.65, P = .01) but not depersonalization (P = .28) or personal accomplishment (P = .24). Depersonalization and personal accomplishment did not correlate with resident performance (P = .12 and P = .75, respectively); however, increased emotional exhaustion showed a significant correlation with higher resident performance during periods when burnout was reported (r(6) = 0.76, P = .047). Conclusions: Dynamic measurement of resting heart rate variability may offer an objective measure of burnout in thoracic surgery residents. Thoracic surgery residents who report high levels of burnout in this cohort maintained the ability to meet program-designated milestones at or above the level expected of their postgraduate year.

Context-Responsive Anticoagulation Reduces Complications in Pediatric Extracorporeal Membrane Oxygenation.

Purpose: We sought to determine the impact of a comprehensive, context-responsive anticoagulation and transfusion guideline on bleeding and thrombotic complication rates and blood product utilization during extracorporeal membrane oxygenation (ECMO). Design: Single-center, observational pre- and post-implementation cohort study. Setting: Academic pediatric hospital. Patients: Patients in the PICU, CICU, and NICU receiving ECMO support. Interventions: Program-wide implementation of a context-responsive anticoagulation and transfusion guideline. Measurements: Pre-implementation subjects consisted of all patients receiving ECMO between January 1 and December 31, 2012, and underwent retrospective chart review. Post-implementation subjects consisted of all ECMO patients between September 1, 2013, and December 31, 2014, and underwent prospective data collection. Data collection included standard demographic and admission data, ECMO technical specifications, non-ECMO therapies, coagulation parameters, and blood product administration. A novel grading scale was used to define hemorrhagic complications (major, intermediate, and minor) and major thromboembolic complications. Main Results: Seventy-six ECMO patients were identified: 31 during the pre-implementation period and 45 in the post-implementation period. The overall observed mortality was 33% with no difference between groups. Compared to pre-implementation, the post-implementation group experienced fewer major hemorrhagic and major thrombotic complications and less severe hemorrhagic complications and received less RBC transfusion volume per kg. Conclusions: Use of a context-responsive anticoagulation and transfusion guideline was associated with a reduction in hemorrhagic and thrombotic complications and reduced RBC transfusion requirements. Further evaluation of guideline content, compliance, performance, and sustainability is needed.

Alterations in pancreatic islet cell function in response to small bowel resection.

After 50% proximal small bowel resection (SBR) in mice, we have demonstrated hepatic steatosis, impaired glucose metabolism without insulin resistance, and increased pancreatic islet area. We sought to determine the consequences of SBR on pancreatic ß-cell morphology, proliferation, and expression of a key regulatory hormone, glucagon-like peptide-1 (GLP-1). C57BL/6 mice underwent 50% SBR or sham operation. At 10 wk, pancreatic insulin content and secretion was measured by ELISA. Immunohistochemistry was performed to determine structural alterations in pancreatic α-and ß-cells. Western blot analysis was used to measure GLP-1R expression, and immunoassay was used to measure plasma insulin and GLP-1. Experiments were repeated by administering a GLP-1 agonist (exendin-4) to a cohort of mice following SBR. After SBR, there was pancreatic islet hypertrophy and impaired glucose tolerance. The proportion of α and ß cells was not grossly altered. Whole pancreas and pancreatic islet insulin content was not significantly different; however, SBR mice demonstrated decreased insulin secretion in both static incubation and islet perfusion experiments. The expression of pancreatic GLP-1R was decreased approximately twofold after SBR, compared with sham and serum GLP-1, was decreased. These metabolic derangements were mitigated after administration of the GLP-1 agonist. Following massive SBR, there is significant hypertrophy of pancreatic islet cells with morphologically intact α- and ß-cells. Significantly reduced pancreatic insulin release in both static and dynamic conditions demonstrate a perturbed second phase of insulin secretion. GLP-1 is a key mediator of this amplification pathway. Decreased expression of serum GLP-1 and pancreatic GLP-1R in face of no change in insulin content presents a novel pathway for enteropancreatic glucose regulation following SBR.NEW & NOTEWORTHY Metabolic changes occur following intestinal resection; however, the effects on pancreatic function are unknown. Prior studies have demonstrated that glucagon-like protein-1 (GLP-1) signaling is a crucial player in the improved insulin sensitivity after bariatric surgery. In this study, we explore the effect of massive small bowel resection on gut hormone physiology and provide novel insights into the enteropancreatic axis.

Barriers and Facilitators of Colorectal Cancer Screening in a Federally Qualified Health Center (FQHC).

INTRODUCTION: Colorectal cancer is a leading cause of cancer-related mortality in the United States. Current screening recommendations for individuals aged 50 to 75 years include colonoscopy every 10 years, flexible sigmoidoscopy every 5 years, or annual stool-based testing. Stool-based testing, including fecal immunochemical tests (FITs), are cost effective, easy to perform at home, and noninvasive, yet many patients fail to return testing kits and go unscreened. The purpose of the study was to identify patient characteristics and perceived barriers and facilitators of FIT return. METHODS: Patients in a large, federally qualified health center who received a FIT kit order between January 1 and July 1, 2017 were identified. We compared sociodemographic and health characteristics between patients who returned and did not return FITs. We used telephone surveys to nonreturners to identify potential barriers (cost, knowledge, psychosocial factors) and facilitators (prepaid postage, outreach) of FIT kit return. An online survey of clinicians assessed perceived patient barriers and facilitators of colorectal cancer screening. RESULTS: Of the 875 patients who received a FIT order, 435 (49.7%) did not return the kit and 121 of the nonreturners completed a telephone survey. Current smokers had an increased risk of FIT nonreturn compared with never smokers (RR = 1.32; 95% CI, 1.13-1.54). Forgetfulness and lack of motivation were the most common FIT return barriers perceived by both patients and clinicians. Prepaid postage with return address on FIT return envelopes and live call reminders were the most commonly reported facilitators. Barriers and facilitators varied greatest between English- and Spanish-speaking patients. CONCLUSION: In this study, the most common perceived barriers to return of screening fecal test kits were forgetfulness and lack of motivation. The most common perceived facilitators were live call reminders and postage-paid return envelopes. Understanding barriers and facilitators to FITs may be necessary to enhance cancer screening rates in underserved patient populations.

Hepatocyte and stellate cell deletion of liver fatty acid binding protein reveals distinct roles in fibrogenic injury.

Liver fatty acid binding protein (L-Fabp) modulates lipid trafficking in enterocytes, hepatocytes, and hepatic stellate cells (HSCs). We examined hepatocyte vs. HSC L-Fabp deletion in hepatic metabolic adaptation and fibrotic injury. Floxed L-Fabp mice were bred to different transgenic Cre mice or injected with adeno-associated virus type 8 (AAV8) Cre and fed diets to promote steatosis and fibrosis or were subjected to either bile duct ligation or CCl4 injury. Albumin-Cre-mediated L-Fabp deletion revealed recombination in hepatocytes and HSCs; these findings were confirmed with 2 other floxed alleles. Glial fibrillary acid protein-Cre and platelet-derived growth factor receptor ß-Cre-mediated L-Fabp deletion demonstrated recombination only in HSCs. Mice with albumin promoter-driven Cre recombinase (Alb-Cre)-mediated or AAV8-mediated L-Fabp deletion were protected against food withdrawal-induced steatosis. Mice with Alb-Cre-mediated L-Fabp deletion were protected against high saturated fat-induced steatosis and fibrosis, phenocopying germline L-Fabp-/- mice. Mice with HSC-specific L-Fabp deletion exhibited retinyl ester depletion yet demonstrated no alterations in fibrosis. On the other hand, fibrogenic resolution after CCl4 administration was impaired in mice with Alb-Cre-mediated L-Fabp deletion. These findings suggest cell type-specific roles for L-Fabp in mitigating hepatic steatosis and in modulating fibrogenic injury and reversal.-Newberry, E. P., Xie, Y., Lodeiro, C., Solis, R., Moritz, W., Kennedy, S., Barron, L., Onufer, E., Alpini, G., Zhou, T., Blaner, W. S., Chen, A., Davidson, N. O. Hepatocyte and stellate cell deletion of liver fatty acid binding protein reveal distinct roles in fibrogenic injury.

Intestinal epithelial cell-specific Raptor is essential for high fat diet-induced weight gain in mice.

Mammalian target of rapamycin complex 1 (mTORC1) is a major regulator of cell growth and proliferation through fuel sensing. Systemic inhibition of mTOR as well as manipulation of its downstream products prevent diet-induced obesity. The purpose of this study was to determine the consequences of intestine-targeted mTORC1 inhibition. To attenuate intestinal mTORC1 activity, Villin-CreER mice were crossed with Raptorflox/flox mice, creating an intestinal-specific Raptor null line (i-Raptor -/-). Mice were fed a high fat diet (HFD) and compositional changes as well as food intake levels were assessed. Over a five-week time course, i-Raptor -/- mice consistently gained less body weight on a HFD compared to wildtype (WT) mice secondary to significantly reduced food intake. Importantly, the i-Raptor -/- mice did not appear to be malnourished, demonstrated by their preservation of lean body mass. i-Raptor -/- mice also maintained a normal metabolic profile without significant changes in triglyceride or fasting glucose levels. Further investigation revealed that GDF-15 mRNA expression was significantly enhanced in i-Raptor -/- enterocytes when refed with HFD after overnight starvation. In summary, our study establishes that loss of intestinal specific-mTORC1 is protective of the development of diet-induced obesity by reducing food intake without altering the metabolic profile.