Robotic Applications in Cardiac Surgery

Traditionally, cardiac surgery has been performed through a median sternotomy, which allows the surgeon generous access to the heart and surrounding great vessels. As a paradigm shift in the size and location of incisions occurs in cardiac surgery, new methods have been developed to allow the surgeon the same amount of dexterity and accessibility to the heart in confined spaces and in a less invasive manner. Initially, long instruments without pivot points were used, however, more recent robotic telemanipulation systems have been applied that allow for improved dexterity, enabling the surgeon to perform cardiac surgery from a distance not previously possible. In this rapidly evolving field, we review the recent history and clinical results of using robotics in cardiac surgery

Quantum dot labeling of mesenchymal stem cells

<p>Abstract</p> <p>Background</p> <p>Mesenchymal stem cells (MSCs) are multipotent cells with the potential to differentiate into bone, cartilage, fat and muscle cells and are being investigated for their utility in cell-based transplantation therapy. Yet, adequate methods to track transplanted MSCs <it>in vivo </it>are limited, precluding functional studies. Quantum Dots (QDs) offer an alternative to organic dyes and fluorescent proteins to label and track cells <it>in vitro </it>and <it>in vivo</it>. These nanoparticles are resistant to chemical and metabolic degradation, demonstrating long term photostability. Here, we investigate the cytotoxic effects of <it>in vitro </it>QD labeling on MSC proliferation and differentiation and use as a cell label in a cardiomyocyte co-culture.</p> <p>Results</p> <p>A dose-response to QDs in rat bone marrow MSCs was assessed in Control (no-QDs), Low concentration (LC, 5 nmol/L) and High concentration (HC, 20 nmol/L) groups. QD yield and retention, MSC survival, proinflammatory cytokines, proliferation and DNA damage were evaluated in MSCs, 24 -120 hrs post QD labeling. In addition, functional integration of QD labeled MSCs in an <it>in vitro </it>cardiomyocyte co-culture was assessed. A dose-dependent effect was measured with increased yield in HC vs. LC labeled MSCs (93 ± 3% vs. 50% ± 15%, p < 0.05), with a larger number of QD aggregates per cell in HC vs. LC MSCs at each time point (p < 0.05). At 24 hrs >90% of QD labeled cells were viable in all groups, however, at 120 hrs increased apoptosis was measured in HC vs. Control MSCs (7.2% ± 2.7% vs. 0.5% ± 0.4%, p < 0.05). MCP-1 and IL-6 levels doubled in HC MSCs when measured 24 hrs after QD labeling. No change in MSC proliferation or DNA damage was observed in QD labeled MSCs at 24, 72 and 120 hrs post labeling. Finally, in a cardiomyocyte co-culture QD labeled MSCs were easy to locate and formed functional cell-to-cell couplings, assessed by dye diffusion.</p> <p>Conclusion</p> <p>Fluorescent QDs label MSC effectively in an <it>in vitro </it>co-culture model. QDs are easy to use, show a high yield and survival rate with minimal cytotoxic effects. Dose-dependent effects suggest limiting MSC QD exposure.</p

Early cell loss associated with mesenchymal stem cell cardiomyoplasty

Background: Human mesenchymal stem cells (hMSCs) show potential for therapeutic cellular cardiomyoplasty. However, a range of delivery methods, including direct intramyocardial injection, have resulted in poor engraftment in vivo. We used the in vivo rat heart model to study hMSC engraftment and retention in a normal beating heart. Materials and Methods: HMSCs transfected with green fluorescent protein were injected into the left ventricle (LV) of immunocompetent rats. Hearts were cryopreserved 30 minutes (Group A), 24 hours (Group B), and 5 days (Group C) post hMSC delivery. HMSC retention was estimated using confocal fluorescence microscopy and immunohistochemistry. Measured values were compared to projected GFP-positive cellular volumes. Immunohistochemical analyses probed for the presence of human cells with human prolyl hydroxylase beta (p4hβ) and an immune response with murine monocyte/macrophage antigen (CD68). Results: HMSC retention decreased significantly from 30 minutes to 5 days (p<0.05). In Group A the projected GFP positive cellular volume of 31% correlated with measured values and was significantly greater than the 1% predicted cellular volume in Group C. Moreover, human p4hβ was detected in Groups A and B, and not in Group C. Conversely, CD68 was detected in Groups B and C and not in Group A. Conclusions: In immunocompetent rats, engraftment and retention of hMSCs delivered intramyocardially significantly declines over a five day period. The influx of monocytes/macrophages suggests an unfavorable micro-environment for exogenous stem cell survival, confirmed by the absence of human cells detected five days post injection

Factors Associated with Discharge to a Skilled Nursing Facility after Transcatheter Aortic Valve Replacement Surgery

An assumption regarding transcatheter aortic valve replacement (TAVR), a minimally invasive procedure for treating aortic stenosis, is that patients remain at, or near baseline and soon return to their presurgical home to resume activities of daily living. However, this does not consistently occur. The purpose of this study was to identify preoperative factors that optimally predict discharge to a skilled nursing facility (SNF) after TAVR. Delineation of these conditions is an important step in developing a risk stratification model to assist in making informed decisions. Data was extracted from the American College of Cardiology (ACC) transcatheter valve therapy (TVT) registry and the Society of Thoracic Surgeons (STS) database on 285 patients discharged from 2012–2017 at a tertiary referral heart institute located in the southeastern region of the United States. An analysis of assessment, clinical and demographic variables was used to estimate relative risk (RR) of discharge to a SNF. The majority of participants were female (55%) and white (84%), with a median age of 82 years (interquartile range = 9). Approximately 27% (n = 77) were discharged to a SNF. Age > 75 years (RR = 2.3, p = 0.0026), female (RR = 1.6, p = 0.019), 5-meter walk test (5MWT) >7 s (RR = 2.0, p = 0.0002) and not using home oxygen (RR = 2.9, p = 0.0084) were identified as independent predictive factors for discharge to a SNF. We report a parsimonious risk-stratification model that estimates the probability of being discharged to a SNF following TAVR. Our findings will facilitate making informed treatment decisions regarding this older patient population

The Effect of Race and Chronic Obstructive Pulmonary Disease on Long-Term Survival after Coronary Artery Bypass Grafting

Background: Chronic obstructive pulmonary disease (COPD) is a known predictor of decreased long-term survival after coronary artery bypass grafting (CABG). Differences in survival by race have not been examined. Methods: A retrospective cohort study was conducted of CABG patients between 2002 and 2011. Long-term survival was compared in patients with and without COPD and stratified by race. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. Results: A total of 984 (20%) patients had COPD (black n = 182; white n = 802) at the time of CABG (N = 4,801). The median follow-up for study participants was 4.4 years. COPD was observed to be a statistically significant predictor of decreased survival independent of race following CABG (no COPD: HR = 1.0; white COPD: adjusted HR = 1.9, 95% CI = 1.7–2.3; black COPD: adjusted HR = 1.6, 95% CI = 1.1–2.2). Conclusion: Contrary to the expected increased risk of mortality among black COPD patients in the general population, a similar survival disadvantage was not observed in our CABG population

Reduction of Ischemia/Reperfusion Injury With Bendavia, a Mitochondria-Targeting Cytoprotective Peptide

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Monoamine Oxidase is a Major Determinant of Redox Balance in Human Atrial Myocardium and is Associated With Postoperative Atrial Fibrillation

BACKGROUND: Onset of postoperative atrial fibrillation (POAF) is a common and costly complication of heart surgery despite major improvements in surgical technique and quality of patient care. The etiology of POAF, and the ability of clinicians to identify and therapeutically target high-risk patients, remains elusive. METHODS AND RESULTS: Myocardial tissue dissected from right atrial appendage (RAA) was obtained from 244 patients undergoing cardiac surgery. Reactive oxygen species (ROS) generation from multiple sources was assessed in this tissue, along with total glutathione (GSHt) and its related enzymes GSH-peroxidase (GPx) and GSH-reductase (GR). Monoamine oxidase (MAO) and NADPH oxidase were observed to generate ROS at rates 10-fold greater than intact, coupled mitochondria. POAF risk was significantly associated with MAO activity (Quartile 1 [Q1]: adjusted relative risk [ARR]=1.0; Q2: ARR=1.8, 95% confidence interval [CI]=0.84 to 4.0; Q3: ARR=2.1, 95% CI=0.99 to 4.3; Q4: ARR=3.8, 95% CI=1.9 to 7.5; adjusted Ptrend=0.009). In contrast, myocardial GSHt was inversely associated with POAF (Quartile 1 [Q1]: adjusted relative risk [ARR]=1.0; Q2: ARR=0.93, 95% confidence interval [CI]=0.60 to 1.4; Q3: ARR=0.62, 95% CI=0.36 to 1.1; Q4: ARR=0.56, 95% CI=0.34 to 0.93; adjusted Ptrend=0.014). GPx also was significantly associated with POAF; however, a linear trend for risk was not observed across increasing levels of the enzyme. GR was not associated with POAF risk. CONCLUSIONS: Our results show that MAO is an important determinant of redox balance in human atrial myocardium, and that this enzyme, in addition to GSHt and GPx, is associated with an increased risk for POAF. Further investigation is needed to validate MAO as a predictive biomarker for POAF, and to explore this enzyme's potential role in arrhythmogenesis