Tobacco use, self-reported professional dental cleaning habits, and lung adenocarcinoma diagnosis are associated with bronchial and lung microbiome alpha diversity.

RATIONALE: The lung microbiome is an inflammatory stimulus whose role in the development of lung malignancies is incompletely understood. We hypothesized that the lung microbiome associates with multiple clinical factors, including the presence of a lung malignancy. OBJECTIVES: To assess associations between the upper and lower airway microbiome and multiple clinical factors including lung malignancy. METHODS: We conducted a prospective cohort study of upper and lower airway microbiome samples from 44 subjects undergoing lung lobectomy for suspected or confirmed lung cancer. Subjects provided oral (2), induced sputum, nasopharyngeal, bronchial, and lung tissue (3) samples. Pathologic diagnosis, age, tobacco use, dental care history, lung function, and inhaled corticosteroid use were associated with upper and lower airway microbiome findings. MEASUREMENTS AND MAIN RESULTS: Older age was associated with greater Simpson diversity in the oral and nasopharyngeal sites (p = 0.022 and p = 0.019, respectively). Current tobacco use was associated with greater lung and bronchus Simpson diversity (p < 0.0001). Self-reported last profession dental cleaning more than 6 months prior (vs. 6 or fewer months prior) was associated with lower lung and bronchus Simpson diversity (p < 0.0001). Diagnosis of a lung adenocarcinoma (vs. other pathologic findings) was associated with lower bronchus and lung Simpson diversity (p = 0.024). Last professional dental cleaning, dichotomized as ≤ 6 months vs. >6 months prior, was associated with clustering among lung samples (p = 0.027, R2 = 0.016). Current tobacco use was associated with greater abundance of pulmonary pathogens Mycoplasmoides and Haemophilus in lower airway samples. Self-reported professional dental cleaning ≤ 6 months prior (vs. >6 months prior) was associated with greater bronchial Actinomyces and lung Streptococcus abundance. Lung adenocarcinoma (vs. no lung adenocarcinoma) was associated with lower Lawsonella abundance in lung samples. Inhaled corticosteroid use was associated with greater abundance of Haemophilus among oral samples and greater Staphylococcus among lung samples. CONCLUSIONS: Current tobacco use, recent dental cleaning, and a diagnosis of adenocarcinoma are associated with lung and bronchial microbiome α-diversity, composition (ß-diversity), and the abundance of several respiratory pathogens. These findings suggest that modifiable habits (tobacco use and dental care) may influence the lower airway microbiome. Larger controlled studies to investigate these potential associations are warranted.

An Adjuvant Stem Cell Patch with Coronary Artery Bypass Graft Surgery Improves Diastolic Recovery in Porcine Hibernating Myocardium.

Diastolic dysfunction persists despite coronary artery bypass graft surgery (CABG) in patients with hibernating myocardium (HIB). We studied whether the adjunctive use of a mesenchymal stem cells (MSCs) patch during CABG improves diastolic function by reducing inflammation and fibrosis. HIB was induced in juvenile swine by placing a constrictor on the left anterior descending (LAD) artery, causing myocardial ischemia without infarction. At 12 weeks, CABG was performed using the left-internal-mammary-artery (LIMA)-to-LAD graft with or without placement of an epicardial vicryl patch embedded with MSCs, followed by four weeks of recovery. The animals underwent cardiac magnetic resonance imaging (MRI) prior to sacrifice, and tissue from septal and LAD regions were collected to assess for fibrosis and analyze mitochondrial and nuclear isolates. During low-dose dobutamine infusion, diastolic function was significantly reduced in HIB compared to the control, with significant improvement after CABG + MSC treatment. In HIB, we observed increased inflammation and fibrosis without transmural scarring, along with decreased peroxisome proliferator-activated receptor-gamma coactivator (PGC1α), which could be a possible mechanism underlying diastolic dysfunction. Improvement in PGC1α and diastolic function was noted with revascularization and MSCs, along with decreased inflammatory signaling and fibrosis. These findings suggest that adjuvant cell-based therapy during CABG may recover diastolic function by reducing oxidant stress-inflammatory signaling and myofibroblast presence in the myocardial tissue.

Randomized Trial of Endoscopic or Open Vein-Graft Harvesting for Coronary-Artery Bypass.

BACKGROUND: The saphenous-vein graft is the most common conduit for coronary-artery bypass grafting (CABG). The influence of the vein-graft harvesting technique on long-term clinical outcomes has not been well characterized. METHODS: We randomly assigned patients undergoing CABG at 16 Veterans Affairs cardiac surgery centers to either open or endoscopic vein-graft harvesting. The primary outcome was a composite of major adverse cardiac events, including death from any cause, nonfatal myocardial infarction, and repeat revascularization. Leg-wound complications were also evaluated. RESULTS: A total of 1150 patients underwent randomization. Over a median follow-up of 2.78 years, the primary outcome occurred in 89 patients (15.5%) in the open-harvest group and 80 patients (13.9%) in the endoscopic-harvest group (hazard ratio, 1.12; 95% confidence interval [CI], 0.83 to 1.51; P=0.47). A total of 46 patients (8.0%) in the open-harvest group and 37 patients (6.4%) in the endoscopic-harvest group died (hazard ratio, 1.25; 95% CI, 0.81 to 1.92); myocardial infarctions occurred in 34 patients (5.9%) in the open-harvest group and 27 patients (4.7%) in the endoscopic-harvest group (hazard ratio, 1.27; 95% CI, 0.77 to 2.11), and revascularization occurred in 35 patients (6.1%) in the open-harvest group and 31 patients (5.4%) in the endoscopic-harvest group (hazard ratio, 1.14; 95% CI, 0.70 to 1.85). Leg-wound infections occurred in 18 patients (3.1%) in the open-harvest group and in 8 patients (1.4%) in the endoscopic-harvest group (relative risk, 2.26; 95% CI, 0.99 to 5.15). CONCLUSIONS: Among patients undergoing CABG, we did not find a significant difference between open vein-graft harvesting and endoscopic vein-graft harvesting in the risk of major adverse cardiac events. (Funded by the Cooperative Studies Program, Office of Research and Development, Department of Veterans Affairs; REGROUP ClinicalTrials.gov number, NCT01850082 .).

Utility of nuclear stress imaging in predicting long-term outcomes one-year post CABG Surgery.

BACKGROUND: Early MPI after CABG is currently considered rarely appropriate in asymptomatic patients. This study aimed to identify prognostic value of nuclear stress-imaging post-CABG. METHODS: This was a single center prospective study looking at long-term outcomes post-CABG. Per protocol participants underwent SPECT-MPI stress testing and coronary angiogram on the same day, 1-year following CABG. Defect size was semi-quantified. The primary outcomes were the composite of death and congestive heart failure. RESULTS: Eighty-four participants underwent nuclear stress-imaging and angiography, with a median follow-up of 11.1 years. Three separate stress findings predicted the primary outcome: inability to reach stage 3 of a Bruce protocol (OR 7.3, CI 2.4-22.1, P < 0.001), LVEF < 45% (OR 4.0, CI 1.1-15.3, P = 0.041) and a moderate-large stress defect size (HR 2.31, CI 1.1-1.5, P = 0.04). These findings appear to be additive and strongest among patients who underwent exercise stress testing (HR 10.6, CI 3.6-30.6, P < 0.001). Graft disease was identified in 39 (46%) patients and compared to those individuals with no graft disease, did not predict long-term adverse outcomes (P = 0.29). CONCLUSION: In clinically stable patients early after revascularization with CABG, SPECT-MPI can identify patients at higher risk of heart failure and death.

NT-Pro BNP Predicts Myocardial Injury Post-vascular Surgery and is Reduced with CoQ10: A Randomized Double-Blind Trial.

BACKGROUND: NT-Pro BNP levels provide incremental value in perioperative risk assessment prior to major noncardiac surgery. Whether they can be pharmacologically modified in patients prior to an elective vascular operation is uncertain. METHODS: A double-blind, randomized controlled trial was implemented at a single institution. Patients were screened during their preoperative vascular clinic appointment and randomly assigned to CoQ10 (400 mg per day) versus Placebo for 3 days prior to surgery. Biomarkers, including NT-Pro BNP, troponin I and C-reactive protein were obtained prior to and following surgery for up to 48 hours. The primary endpoint was postoperative NT-Pro BNP levels, and secondary endpoint measures included myocardial injury, defined by an elevated cardiac troponin level and length of stay. RESULTS: One hundred and twenty-three patients were randomized to receive either CoQ10 (N = 62) versus Placebo (N = 61) for 3 days before vascular surgery. Preoperative cardiac risks included ischemic heart disease (N = 52), CHF (N = 12), stroke (N = 23), and diabetes mellitus (N = 48) and the planned vascular procedures were infrainguinal (N = 78), carotid (N = 36), and intraabdominal (N = 9). There were no intergroup differences in these clinical variables. NT-Pro BNP levels (median; IQs) in the CoQ10 and Placebo groups were 179 (75-347) and 217 (109-585) pg/ml, respectively, (P = 0.08) preoperatively, and 397 (211-686) and 591 (288-1,433) pg/ml respectively, (P = 0.01) at 24 hours following surgery. Patients with an elevated NT-Pro BNP had a higher incidence of myocardial injury, (58% vs. 20%; P < 0.01) and a longer hospital stay (4.4 ± 3.8 vs. 2.8 ± 3.2 days; P < 0.02) compared with individuals without an elevated NT-Pro BNP level. CONCLUSIONS: NT-Pro BNP levels predict adverse events post-vascular surgery and are lowered in those patients assigned to preoperative administration of CoQ10. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT03956017. Among patients undergoing elective vascular surgery, 123 patients were randomized to either CoQ10 (400 mg/day) versus placebo for three days preoperatively. NT-Pro BNP levels (median; IQs) in the CoQ10 and Placebo groups were 179 (75-347) and 217 (109-585) pg/ml, respectively, (P = 0.08) preoperatively, and 397 (211-686) and 591 (288-1,433) pg/ml, respectively, (P = 0.01) post-surgery. Patients with an elevated NT-Pro BNP had a higher incidence of myocardial injury (58% vs. 20%; P < 0.01) and a longer hospital stay (4.4 ± 3.8 vs. 2.8 ± 3.2 days; P < 0.02) compared with individuals without an NT-Pro BNP elevation. In conclusion, BNP predicts adverse outcomes and can be reduced with preoperative CoQ10.

Single Versus Bilateral Lung Transplantation for Idiopathic Pulmonary Fibrosis in the Lung Allocation Score Era.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease. Lung transplantation is the only therapy associated with prolonged survival. The ideal transplant procedure for IPF is unclear. Outcomes after single transplantation (SLTx) versus bilateral lung transplantation (BLTx) in IPF patients after introduction of the Lung Allocation Score were examined. METHODS: Records of patients undergoing lung transplantation for IPF at our institution between May 2005 and March 2017 were reviewed to examine the effect of transplant laterality. Primary outcomes were overall, rejection-free, and bronchiolitis obliterans (BOS)-free survival at 1 and 5 years post-transplant. RESULTS: Lung transplantation was performed in 151 IPF patients post-Lung Allocation Score. Most recipients were male with average age 59 ± 8 years. SLTx was performed in 94 patients (62%). In the overall cohort, comparative survival between SLTx and BLTx was similar at 1 and 5 years before and after adjusting for age and pulmonary hypertension (PH). SLTx was associated with shorter ventilator time and intensive care unit stay and trended toward improved survival over BLTx in patients without PH. CONCLUSIONS: The use of SLTx versus BLTx in IPF did not correspond to significantly different survival adjusting for age and PH. BLTx was associated with prolonged postoperative ventilation and length of stay compared with SLTx. Patients without PH, all older patients, and patients with PH and advanced disease should be considered for SLTx for IPF.

Gender differences in long-term survival post-transplant: A single-institution analysis in the lung allocation score era.

The purpose of this study was to clarify the significance of recipient gender status on lung transplant outcomes in a large single-institution experience spanning three decades, we analyzed data from all lung transplants performed in our institution since 1986. Kaplan-Meier curves and Cox proportional hazard models were used to evaluate the effect of recipient characteristics on survival and BOS score ≥1-free survival. Logistic regression analysis was used to explore the association of gender with short-term graft function. About 876 lung transplants were performed between 1986 and 2016. Kaplan-Meier survival estimates at 5 years post-transplant for females vs males in the LAS era were 71% vs 58%. In the LAS era, females showed greater unadjusted BOS≥1-free survival than males (35% vs 25%, P=.02) over 5 years. Female gender was the only factor in the LAS era significantly associated with improved adjusted 5-year survival [HR 0.56 (95% CI 0.33, 0.95) P=.03]. Conversely, in the pre-LAS era female gender was not associated with improved survival. Female recipients showed significantly improved survival over 5 years compared to males in the LAS era. A prospective analysis of biologic and immunologic differences is warranted.

Pioglitazone increases PGC1-α signaling within chronically ischemic myocardium.

The peroxisome proliferator-activated receptor (PPAR)-γ drug pioglitazone (PIO) has been shown to protect tissue against oxidant stress. In a swine model of chronic myocardial ischemia, we tested whether PIO increases PGC1-α signaling and the expression of mitochondrial antioxidant peptides. Eighteen pigs underwent a thoracotomy with placement of a fixed constrictor around the LAD artery. At 8 weeks, diet was supplemented with either PIO (3 mg/kg) or placebo for 4 weeks. Regional myocardial function and blood flow were determined at the time of the terminal study. PGC1-α expression was quantified from nuclear membranes by gels and respiration, oxidant stress markers and proteomics by iTRAQ were determined from isolated mitochondria. In the chronically ischemic LAD region, wall thickening from the PIO and control groups was 42 ± 6 and 45 ± 5 %, respectively (NS) with no intergroup differences in basal blood flow (0.72 ± 0.04 versus 0.74 ± 0.04 ml/min g, respectively; NS). In the PIO group, the expression of nuclear bound PGC1-α was higher (11.3 ± 2.6 versus 4.4 ± 1.4 AU; P < 0.05) and the content of mitochondrial antioxidant peptides including superoxide dismutase 2, aldose reductase, glutathione S-transferase and thioredoxin reductase were greater than controls. Although isolated mitochondria from the PIO group showed lower state 3 respiration (102 ± 13 versus 161 ± 22 nmol/min mg; P < 0.05), no differences in oxidant stress were noted by protein carbonyl (1.7 ± 0.7 versus 1.1 ± 0.1 nmol/mg). Chronic pioglitazone does not reduce regional myocardial blood flow or function in a swine model of chronic myocardial ischemia, but may have an important role in increasing expression of antioxidant proteins through PGC1-α signaling.

Mitochondrial fusion proteins in revascularized hibernating hearts.

BACKGROUND: Hibernating myocardium is characterized by viable yet dysfunctional myocardium secondary to chronic ischemia, with studies demonstrating incomplete early recovery after coronary artery bypass graft (CABG). We tested whether mitochondrial fusion proteins, an indicator of mitochondrial biogenesis, are increased in hibernating myocardium post-CABG. METHODS: A constrictor was placed on the left anterior descending (LAD) artery of nine pigs. Four of these pigs additionally underwent CABG 12 wk later with a left internal mammary artery graft to the LAD distal to the constrictor. Five pigs had a constrictor placed but did not undergo CABG (Hib). Five pigs did not have a constrictor placed (control). Computerized tomography angiography was used to confirm stenosis at the site of constrictor placement and patency of left internal mammary artery grafts. Regional blood flows were determined at baseline and during 40 µg/kg/min dobutamine infusion. Mitochondrial proteins were quantified by Western blot. RESULTS: Blood flow in the LAD region after CABG was lower than remote regions during dobutamine infusion (2.54 ± 0.24 versus 3.46 ± 0.33 mL/min/g; P < 0.05). Electron transport chain proteins were ∼70% lower in Hib compared with those in control and failed to normalize after CABG. Post-CABG, PGC1α nuclear-bound content was increased compared with Hib (9.02 ± 0.48 versus 5.54 ± 0.98 arbitrary units, respectively; P < 0.05), and expression of mitofusins-1 and 2 and optic atrophy-1 more than doubled. CONCLUSIONS: PGC1α and mitochondrial fusion proteins are increased 4 wk post-CABG in hibernating hearts, indicating mitochondrial fusion has begun to occur and signaling early mitochondrial recovery. Future studies should address changes in maximal myocardial oxygen consumption relative to mitochondrial protein expression.

Expression of uncoupling protein-2 remains increased within hibernating myocardium despite successful coronary artery bypass grafting at 4 wk post-revascularization.

BACKGROUND: We have previously shown that mitochondrial uncoupling protein-2 (UCP-2) is increased in a swine model of hibernating myocardium (HM). Although UCP-2 reduces oxidant stress, it can promote inefficiency of the electron transport chain. In this study, we tested whether UCP-2 remains increased in revascularized HM (RHM) after coronary artery bypass grafting (CABG). METHODS: Seven swine underwent thoracotomy with placement of a constrictor on the left anterior descending artery (LAD). Twelve weeks later, a left internal mammary artery graft was placed on the distal LAD. Four weeks post-CABG, computed tomography angiography documented patent grafts and function. At the terminal study, blood flow to the LAD and remote territories were assessed during high dose dobutamine and mitochondria isolated from both regions for analysis. Comparisons were made to a group of swine with HM who underwent constrictor placement without bypass grafting (n = 4). RESULTS: During dobutamine infusion, RHM demonstrated lower blood flows (2.44 ± 0.23 versus 3.43 ± 0.30 mL/min/g; P < 0.05) and reduced wall thickening (33 ± 9% versus 52 ± 13%; P < 0.05) compared with remote regions. RHM had lower respiratory control indices (3.7 ± 0.3 versus 4.3 ± 0.4; P < 0.05) with persistently increased UCP-2 content. CONCLUSIONS: Despite patent grafts, RHM demonstrates a submaximal response to dobutamine infusion and increased mitochondrial UCP-2 expression. These data support the notion that recovery of the mitochondria in RHM is delayed early post-CABG and may contribute to impaired oxygen consumption and contractile reserve during catecholamine challenges.

Recovery of hibernating myocardium: what is the role of surgical revascularization?

Myocardial responses to chronic ischemia represent a continuum of adaptations resulting, over time, in a stress-resistant phenotype. One such adaptation, hibernating myocardium (HM), has increased antioxidant capacity that protects against ischemia-induced oxidative stress. Studies have suggested that revascularization alone may not fully restore cardiac function, highlighting the need for targeted therapies to serve as adjuncts to the innate healing process following revascularization. In our review, we discuss current understanding of HM and the recovery process following surgical revascularization, focusing on animal models of HM to understand implications for human patients.

Impact of lung transplantation on diastolic dysfunction in recipients with pretransplant pulmonary hypertension.

OBJECTIVE: Pulmonary hypertension can cause left ventricular diastolic dysfunction through ventricular interdependence. Moreover, diastolic dysfunction has been linked to adverse outcomes after lung transplant. The impact of lung transplant on diastolic dysfunction in recipients with pretransplant pulmonary hypertension is not defined. In this cohort, we aimed to assess the prevalence of diastolic dysfunction, the change in diastolic dysfunction after lung transplant, and the impact of diastolic dysfunction on lung transplant outcomes. METHODS: In a large, single-center database from January 2011 to September 2021, single or bilateral lung transplant recipients with pulmonary hypertension (mean pulmonary artery pressure > 20 mm Hg) were retrospectively identified. Those without a pre- or post-transplant echocardiogram within 1 year were excluded. Diastolic dysfunction was diagnosed and graded according to the American Society of Echocardiography 2016 guideline on assessment of diastolic dysfunction (present, absent, indeterminate). McNemar's test was used to examine association between diastolic dysfunction pre- and post-transplant. Kaplan-Meier and Cox regression analysis were used to assess associations between pre-lung transplant diastolic dysfunction and post-lung transplant 1-year outcomes, including mortality, major adverse cardiac events, and bronchiolitis obliterans syndrome grade 1 or higher-free survival. RESULTS: Of 476 primary lung transplant recipients, 205 with pulmonary hypertension formed the study cohort (mean age, 56.6 ± 11.9 years, men 61.5%, mean pulmonary artery pressure 30.5 ± 9.8 mm Hg, left ventricular ejection fraction < 55% 9 [4.3%]). Pretransplant, diastolic dysfunction was present in 93 patients (45.4%) (grade I = 8, II = 84, III = 1), absent in 16 patients (7.8%), and indeterminate in 89 patients (43.4%), and 7 patients (3.4%) had missing data. Post-transplant, diastolic dysfunction was present in 7 patients (3.4%) (grade I = 2, II = 5, III = 0), absent in 164 patients (80.0%), and indeterminate in 15 patients (7.3%), and 19 patients (9.3%) had missing data. For those with diastolic dysfunction grades in both time periods (n = 180), there was a significant decrease in diastolic dysfunction post-transplant (148/169 patients with resolved diastolic dysfunction; McNemar's test P < .001). Pretransplant diastolic dysfunction was not associated with major adverse cardiac events (hazard ratio [HR], 1.08, 95% CI, 0.72-1.62; P = .71), bronchiolitis obliterans syndrome-free survival (HR, 0.67, 95% CI, 0.39-1.56; P = .15), or mortality (HR, 0.70, 95% CI, 0.33-1.46; P = .34) at 1 year. CONCLUSIONS: Diastolic dysfunction is highly prevalent in lung transplant candidates with normal left ventricular systolic function and pulmonary hypertension, and resolves in most patients after lung transplant regardless of patient characteristics. Pre-lung transplant diastolic dysfunction was not associated with adverse lung or cardiac outcomes after lung transplant. Collectively, these findings suggest that the presence of diastolic dysfunction in lung transplant recipients with pulmonary hypertension has no prognostic significance, and as such diastolic dysfunction and the associated clinical syndrome of heart failure with preserved ejection fraction should not be considered a relative contraindication to lung transplant in such patients.

Reduced expression of mitochondrial electron transport chain proteins from hibernating hearts relative to ischemic preconditioned hearts in the second window of protection.

Although protection against necrosis has been observed in both hibernating (HIB) and ischemic preconditioned hearts in the second window of protection (SWOP), a comparison of the mitochondrial proteome between the two entities has not been previously performed. Anesthetized swine underwent instrumentation with a fixed constrictor around the LAD artery and were followed for 12 weeks (HIB; N=7). A second group of anesthetized swine underwent ischemic preconditioning by inflating a balloon within the LAD artery 10 times for 2 min, each separated by 2 min reperfusion and were sacrificed 24h later (SWOP; N=7). Myocardial blood flow and high-energy nucleotides were obtained in the LAD region and normalized to remote regions. Post-sacrifice, protein content as measured with iTRAQ was compared in isolated mitochondria from the LAD area of a Sham heart. Basal regional blood flow in the LAD region when normalized to the remote region was 0.86±0.04 in HIB and 1.02±0.02 in SWOP tissue (P<0.05). Despite reduced regional blood flows in HIB hearts, ATP content in the LAD region, when normalized to the remote region was similar in HIB versus SWOP (1.06±0.06 and 1.02±0.05 respectively; NS) as was the transmural phosphocreatine (PCr) to ATP ratio (2.1±0.2 and 2.2±0.2 respectively; NS). Using iTRAQ, 64 common proteins were identified in HIB and SWOP hearts. Compared with SWOP, the relative abundance of mitochondrial proteins involved with electron transport chain (ETC) were reduced in HIB including NADH dehydrogenase, Cytochrome c reductase and oxidase, ATP synthase, and nicotinamide nucleotide transhydrogenase. Within chronically HIB heart tissue with reduced blood flow, the relative abundance of mitochondrial ETC proteins is decreased when compared with SWOP tissue. These data support the concept that HIB heart tissue subjected to chronically reduced blood flow is associated with a down-regulation in the expression of key mitochondrial proteins involved in electron transport.

Calcineurin inhibitors and Clostridium difficile infection in adult lung transplant recipients: the effect of cyclosporine versus tacrolimus.

BACKGROUND: Tacrolimus (FK506) has a superior immunosuppressive effect compared with cyclosporine (CSA) without a significant increase in generalized infectious complications. Differences in specific infections such as Clostridium difficile (CDI) have not been reported. We investigated the relationship between calcineurin inhibitors and CDI, hypothesizing that choice of calcineurin inhibitor (CSA or FK506) after lung transplantation would have no effect on the incidence of CDI. METHODS: We performed a retrospective chart review of lung transplant recipients between June 1, 2000, and December 31, 2005, at a single institution. Positive CDI assays through December 11, 2011, were also recorded. We used Student's t- and chi-squared tests (α = 0.05) to compare CSA and FK506 groups. We calculated adjusted hazard ratios for CDI using Cox proportional hazard models. RESULTS: We identified 217 lung transplant recipients: 106 patients in the CSA group and 111 patients in the FK506 group. A total of 31 patients (27.9%) in the FK506 group developed CDI postoperatively compared with 20 patients (18.9%) in the CSA group (P = 0.16). The adjusted hazard ratio for CDI in the FK506 group was not significantly higher (1.53; 95% confidence interval, 0.78-2.98). There was no significant difference in the intensive care unit or total length of stay, in-hospital incidence rate, time to first CDI episode, or recurrence rate between groups. CONCLUSIONS: The CDI rates were not significantly higher in the FK506 group than the CSA group in our study. These data are consistent with previous studies on FK506 that show no increase in infectious complications over CSA, and demonstrate its continued safety in lung transplantation.

The rise of Clostridium difficile infection in lung transplant recipients in the modern era.

PURPOSE: Clostridium difficile infection (CDI) rates have been rising in recent years. We aimed to characterize CDI in lung transplant recipients in the modern era and hypothesized that CDI would increase the mortality risk. METHODS: We performed a retrospective chart review of patients undergoing transplantation at our center from 1/2006 to 7/2011. Attributes of CDI+ and CDI- groups were compared using Student's t- and chi-square tests (α = 0.05). Multivariate Cox proportional hazard models were used to control for confounding factors. RESULTS: Overall CDI incidence was 22.5%. Seven of 151 patients (4.6%) developed CDI during the initial hospitalization after transplantation (mean time 10.6 ± 6 d) while 27 patients (19.7%) developed CDI after discharge (mean time 467 ± 471 d). Incidence rate was 224.6 cases/100 000 patient-days compared to 110 cases/100 000 patient-days (rate for entire hospital). CDI was not predictive of mortality (HR 2.06, 95% CI 0.94-4.52). CONCLUSION: CDI rates in lung transplant recipients are high in the modern era. No risk factors for CDI were identified. Although not statistically significant, CDI+ patients had a higher risk of death. The economic burden of CDI and trend toward worse outcomes for CDI patients have important implications for post-operative surveillance of CDI-related complications and need for CDI prophylaxis.

Retained catheter dilator in right ventricular outflow tract for 22 years.

We report the case of a 61-year-old male with a retained catheter dilator in the right ventricular outflow tract for over 22 years. The management of retained intravascular foreign objects in the myocardium is reviewed.

Considerations for a Holistic Model in Evaluating Medical Students for Cardiothoracic Surgical Residency.

Program directors are tasked with selecting whom they think will be the best fit for residency and the next leaders of the field. While numerical metrics have played a vital role in this process, recent changes to student evaluation are reducing the availability of these metrics. This poses unique challenges for both applicants and program directors. Here we discuss how this will likely shift the focus on other parts of the application and the consequences (good and bad) of doing so.

Surgical Porcine Model of Chronic Myocardial Ischemia Treated by Exosome-laden Collagen Patch and Off-pump Coronary Artery Bypass Graft.

Chronic myocardial ischemia resulting from progressive coronary artery stenosis leads to hibernating myocardium (HIB), defined as myocardium that adapts to reduced oxygen availability by reducing metabolic activity, thereby preventing irreversible cardiomyocyte injury and infarction. This is distinct from myocardial infarction, as HIB has the potential for recovery with revascularization. Patients with significant coronary artery disease (CAD) experience chronic ischemia, which puts them at risk for heart failure and sudden death. The standard surgical intervention for severe CAD is coronary artery bypass graft surgery (CABG), but it has been shown to be an imperfect therapy, yet no adjunctive therapies exist to recover myocytes adapted to chronic ischemia. To address this gap, a surgical model of HIB using porcine that is amenable to CABG and mimics the clinical scenario was used. The model involves two surgeries. The first operation involves implanting a 1.5 mm rigid constrictor on the left anterior descending (LAD) artery. As the animal grows, the constrictor gradually causes significant stenosis resulting in reduced regional systolic function. Once the stenosis reaches 80%, the myocardial flow and function are impaired, creating HIB. An off-pump CABG is then performed with the left internal mammary artery (LIMA) to revascularize the ischemic region. The animal recovers for one month to allow for optimal myocardial improvement prior to sacrifice. This allows for physiologic and tissue studies of different treatment groups. This animal model demonstrates that cardiac function remains impaired despite CABG, suggesting the need for novel adjunctive interventions. In this study, a collagen patch embedded with mesenchymal stem cell (MSC)-derived exosomes was developed, which can be surgically applied to the epicardial surface distal to LIMA anastomosis. The material conforms to the epicardium, is absorbable, and provides the scaffold for the sustained release of signaling factors. This regenerative therapy can stimulate myocardial recovery that does not respond to revascularization alone. This model translates to the clinical arena by providing means of physiological and mechanistic explorations regarding recovery in HIB.

Stem cell-derived exosome patch with coronary artery bypass graft restores cardiac function in chronically ischemic porcine myocardium.

OBJECTIVE: This study aimed to investigate whether or not the application of a stem cell-derived exosome-laden collagen patch (EXP) during coronary artery bypass grafting (CABG) can recover cardiac function by modulating mitochondrial bioenergetics and myocardial inflammation in hibernating myocardium (HIB), which is defined as myocardium with reduced blood flow and function that retains viability and variable contractile reserve. METHODS: In vitro methods involved exposing H9C2 cardiomyocytes to hypoxia followed by normoxic coculture with porcine mesenchymal stem cells. Mitochondrial respiration was measured using Seahorse assay. GW4869, an exosomal release antagonist, was used to determine the effect of mesenchymal stem cells-derived exosomal signaling on cardiomyocyte recovery. Total exosomal RNA was isolated and differential micro RNA expression determined by sequencing. In vivo studies comprised 48 Yorkshire-Landrace juvenile swine (6 normal controls, 17 HIB, 19 CABG, and 6 CABG + EXP), which were compared for physiologic and metabolic changes. HIB was created by placing a constrictor on the proximal left anterior descending artery, causing significant stenosis but preserved viability by 12 weeks. CABG was performed with or without mesenchymal stem cells-derived EXP application and animals recovered for 4 weeks. Before terminal procedure, cardiac magnetic resonance imaging at rest, and with low-dose dobutamine, assessed diastolic relaxation, systolic function, graft patency, and myocardial viability. Tissue studies of inflammation, fibrosis, and mitochondrial morphology were performed posttermination. RESULTS: In vitro data demonstrated improved cardiomyocyte mitochondrial respiration upon coculture with MSCs that was blunted when adding the exosomal antagonist GW4869. RNA sequencing identified 8 differentially expressed micro RNAs in normoxia vs hypoxia-induced exosomes that may modulate the expression of key mitochondrial (peroxisome proliferator-activator receptor gamma coactivator 1-alpha and adenosine triphosphate synthase) and inflammatory mediators (nuclear factor kappa-light-chain enhancer of activated B cells, interferon gamma, and interleukin 1ß). In vivo animal magnetic resonance imaging studies demonstrated regional systolic function and diastolic relaxation to be improved with CABG + EXP compared with HIB (P = .02 and P = .02, respectively). Histologic analysis showed increased interstitial fibrosis and inflammation in HIB compared with CABG + EXP. Electron microscopy demonstrated increased mitochondrial area, perimeter, and aspect ratio in CABG + EXP compared with HIB or CABG alone (P < .0001). CONCLUSIONS: Exosomes recovered cardiomyocyte mitochondrial respiration and reduced myocardial inflammation through paracrine signaling, resulting in improved cardiac function.

Persistent diastolic dysfunction in chronically ischemic hearts following coronary artery bypass graft.

OBJECTIVE: A porcine model was used to study diastolic dysfunction in hibernating myocardium (HM) and recovery with coronary artery bypass surgery (CABG). METHODS: HM was induced in Yorkshire-Landrace juvenile swine (n = 30) by placing a c-constrictor on left anterior descending artery causing chronic myocardial ischemia without infarction. At 12 weeks, animals developed the HM phenotype and were either killed humanely (HIB group; n = 11) or revascularized with CABG and allowed 4 weeks of recovery (HIB+CABG group; n = 19). Control pigs were matched for weight, age, and sex to the HIB group. Before the animals were killed humanely, cardiac magnetic resonance imaging (MRI) was done at rest and during a low-dose dobutamine infusion. Tissue was obtained for histologic and proinflammatory biomarker analyses. RESULTS: Diastolic peak filling rate was lower in HIB compared with control (5.4 ± 0.7 vs 6.7 ± 1.4 respectively, P = .002), with near recovery with CABG (6.3 ± 0.8, P = .06). Cardiac MRI confirmed preserved global systolic function in all groups. Histology confirmed there was no transmural infarction but showed interstitial fibrosis in the endomysium in both the HIB and HIB+CABG groups compared with normal myocardium. Alpha-smooth muscle actin stain identified increased myofibroblasts in HM that were less apparent post-CABG. Cytokine and proteomic studies in HM showed decreased peroxisome proliferator-activator receptor gamma coactivator 1-alpha (PGC1-α) expression but increased expression of granulocyte-macrophage colony-stimulating factor and nuclear factor kappa-light-chain enhancer of activated B cells (NFκB). Following CABG, PGC1-α and NFκB expression returned to control whereas granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-α, and interferon gamma remained increased. CONCLUSIONS: In porcine model of HM, increased NFκB expression, enhanced myofibroblasts, and collagen deposition along with decreased PGC1-α expression were observed, all of which tended toward normal with CABG. Estimates of impaired relaxation with MRI within HM during increased workload persisted despite CABG, suggesting a need for adjuvant therapies during revascularization.